Language：Japanese  

Noise barrier using hybrid ANC system (Proposal and application of an adaptive robust feedback ANC system)
In this paper, an adaptive robust feedback (FB) active noise control (ANC) system is proposed and applied to the previously developed active noise barrier (ANB) using a hybrid (HB) ANC system, which aims to relieve the indoor noise problem. The FB control is preferred for this small-typed ANB application because only error sensor is required for the FB control system so that a compact controller can be easily realized. In practice, however, the robust stability of the FB controller must be considered. Moreover, the waterbed effect of the FB control will cause noise enhancement at some frequencies out of the target band of control. In order to design a robust controller with limited noise enhancement in real-time control, a modified frequency domain block LMS (modified FDB-LMS, MFDB-LMS) algorithm, which has the reduced computation complexity and the same steady-state performance comparing with the conventional FDB-LMS algorithm, is proposed in this paper, firstly, owing to the easiness to verify the robust stability and the noise enhancement constraints in the frequency domain adaptive process. Then, an internal model control (IMC) typed FB-ANC system exploiting the MFDB-LMS algorithm, into which the constraints to guarantee the robust stability and limit the noise enhancement to within a given value has been integrated, is proposed and applied to the ANB. The effectiveness of the proposed FB-ANC system and the noise attenuation performance of the ANB using the proposed system have been validated by simulations.

DOI： 10.1299/transjsme.15-00532

Language：Japanese  

Noise barrier using hybrid ANC system (Supression of the noise enhancement caused by the waterbed effect and investigation of the noise attenuation performace under various sound field configurations)
In this paper, the hybrid active noise control (HB-ANC) system applied in the active noise barrier (ANB) is improved, and the noise attenuation performace of the ANB is invetigated under four different sound field configurations. This hybird ANB reduces the diffraction noise from top of the ANB and the noise propagated to the head position of the target person behind the ANB simultaneously to achieve higher noise attenuation. However, the waterbed effect of the feedback control part of the HB-ANC system will cause noise enhancement at some frequencies in the control area. In order to solve this problem, the HB-ANC system is improved by adding a filter to cancel the noise enhancement caused by the waterbed effect. Then, the noise attenuation performance of the hybrid ANB under four sound field configurations is evaluated by simulations. The sound field configurations are set up to investigate how the diffraction from side of the ANB and the reflection influence the performance of the ANB. An experiment in the anechoic chamber is also conducted. The results indicate that the low frequency noise attenuation can be obtained in a wide area behind the ANB, and at the head position of the person, the noise attenuation can be ensured within a wider frequency range, even for the sound fields where the uncontrolled diffraction from side and the reflection exist.

DOI： 10.1299/transjsme.15-00064

Language：Japanese  

A noise barrier using hybrid ANC system
In this paper, in order to improve the low frequency noise insulation performance of a noise barrier, a new type of hybrid active noise control (ANC) system is proposed. The proposed system is a combination of feedforward and feedback controller. The reference signal for the feedforward controller is generated in the feedback part, so the reference microphone is not necessary. The feedback controller is used for controlling the acoustic boundary to insulate the diffraction noise, and the feedforward controller is used for reducing the noise at the error microphone which is set to be near the ears of people. As a preliminary work, this paper validated the effectiveness of the proposed ANC system both by simulations and by an experiment. The result shows that the active noise insulation provided by feedback controller and the noise attenuation provided by feedforward controller accumulated in the control area, so that the proposed ANC system has better control performance than individual feedforward or feedback ANC system.

DOI： 10.1299/transjsme.2014dr0165

Language：Japanese  

Two-Dimensional Acoustic Analysis by Concentrated Mass Model
FDTD method and CIP method are used for an acoustic analysis in time domain. However, these methods do not take into account a sound attenuation from viscosity. In our study, we propose a concentrated mass model which consists of spring-mass-damper system to perform a two-dimensional acoustic analysis. The dampers of this model consider viscosity of air. In this paper, we derive mass, connecting springs, and connecting dampers. The characteristic of connecting spring is derived from the condition of adiabatic change of air, and the connecting damper is derived from the normal stress. To confirm the validity of the proposed model, the numerical results obtained by the concentrated mass model are compared with the theoretical value of a traveling wave, and with the theoretical value of the natural frequency. All numerical computational results agree very well with the theoretical values. Therefore, it is concluded that the proposed model is valid for the two-dimensional acoustic analysis.

DOI： 10.1299/kikaib.79.744

Language：English  

Language：Japanese  

Active Noise Control for a Moving Evaluation Point Using Stepsize Vector
In three-dimension acoustic field, it is difficult to control in the whole room using active noise control (ANC) technique. Instead, around-head-control is investigated in this paper. By using around-head-control method, an object person can get the noise reduction effect without controlling in the whole space, because it makes around the head quiet locally. Therefore, to realize around-head-control, it is necessary for a controller to follow the head movement. However, there is a problem that the control effect under the movement is worse, and the recovery of control effect after movement is slow by conventional ANC. Against this problem, we propose the new method of improving the adaptation speed when an evaluation point moves. In the algorithm, the updating size appropriate to each coefficient of the adaptive filter is calculated by using a step size vector. The step size vector is calculated from the coefficient of adaptive filter before updating. The validity of the proposal method is shown by the numerical simulation and the experiment in an anechoic chamber.

DOI： 10.1299/kikaic.78.1670

Language：Japanese  

Active Control against Impact Noise Using Frequency Domain Adaptive Algorithm
Noise control has been developed to establish the comfortable soundscape even if our house life. Floor impact noise such as the sound of footsteps or falling object becomes a problem in an apartment house. Floor impact noise has a peak at the low-frequency range. Passive noise control is not effective against low-frequency noise. Therefore, the purpose of this paper is to control the impact noise using active noise control. Since each impact noise is generated in a short period, LMS algorithm is difficult to use because of its slow convergence characteristics. On the other hand, frequency domain adaptive algorithm is known for fast convergence characteristics. In this paper, the effectiveness of active noise control using frequency domain adaptive algorithm is confirmed through simulations and experiments.

DOI： 10.1299/kikaic.78.1655

Language：English  

Language：Japanese  

Language：Japanese  

Language：English  

Language：Japanese  

Language：Japanese  

Language：English  

Language：Japanese  

Language：Japanese  

Language：English  

Language：Japanese  

Language：English  

Language：Japanese  

Language：Japanese  

Language：Japanese  

Language：English  

Language：Japanese  

Language：Japanese  

Publisher：Limnology and Oceanography: Methods  

It is empirically known that fish exposed to harmful algal blooms (HABs) exhibit abnormal behavior. This might serve as a method for early detection of HABs. There has been no report of the detection of behavioral abnormalities of fish exposed to harmful algae using machine learning. In this study, the behavior of Oryzias javanicus (Java medaka) exposed in a stepwise manner to the HAB species Karenia mikimotoi at densities of 0 cells mL−1 (control), 1 × 103 cells mL−1 (nonlethal), and 5 × 103 cells mL−1 (sublethal) was recorded for 30 min at each cell density using two digital cameras connected to a software that tracked behavioral metrics of fish. The level of anomaly in the behavior of Java medaka was then analyzed using one-class support vector machines (OC-SVM) to determine whether the behavioral changes could be considered abnormal. The results revealed abnormal swimming behavior evidenced by an increase of swimming speed, a decrease of shoaling behavior, and a greater depth of swimming in Java medaka exposed especially to the sublethal K. mikimotoi density. The medaka exposed to K. mikimotoi also displayed physical deformities of their gills that were thought to have caused their abnormal behavior. This supposition was confirmed by further analysis using OC-SVM because the behavior of groups exposed to nonlethal and sublethal densities of K. mikimotoi were considered abnormal compared with that of the control groups. The results of this study show the possibility of using this system for early and real-time detection of HABs.

DOI： 10.1002/lom3.10613

Web of Science

Scopus

Language：English   Publishing type：Research paper (scientific journal)  

DOI： doi: 10.1002/lom3.10613

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.euromechflu.2024.02.002

Language：English   Publisher：The Japan Society of Mechanical Engineers  

<p>In a parallel-motion-type eddy current damper comprising a magnet and conducting plate, the magnet is assumed stationary, and the conductor moves parallel to the xy-plane of a static coordinate system O-<i>xyz</i>. In a previous study, we proved that when an arbitrarily dimensioned rectangular magnet and conductor are symmetrically positioned along both the <i>x-</i> and <i>y-</i> axes at an instant, the condition that “the gradient of scalar potential is zero” (GSPZ condition) is established throughout the conductor in a stationary-conductor coordinate system. For an eddy current damper comprising a ring magnet and conducting disk, the equations of the magnetic vector potential and scalar potential are different from those for an eddy current damper comprising a rectangular magnet and conductor. In this study, we verified whether the GSPZ condition can be applied to an eddy current damper comprising a ring magnet and conducting disk. First, using the three-dimensional finite element method (3D-FEM), we analyzed the eddy current distribution in an eddy current damper comprising a single ring magnet and conducting disk, and we found that the GSPZ condition is valid for an arbitrary diameter of the conducting disk. Second, we verified that the GSPZ condition can be applied to an eddy current damper comprising a combination of ring magnets with oppositely aligned magnetic poles and two conducting disks with arbitrary diameters. Third, we calculated the magnetic damping forces of both eddy current dampers using Fleming’s left-hand rule under the GSPZ condition (GSPZ-A method), and the results were in good agreement with those obtained using the 3D-FEM.</p>

DOI： 10.1299/mej.23-00207

Web of Science

CiNii Research

Language：English   Publishing type：Research paper (other academic)  

Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)  

researchmap

Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>Region separation control of sound field can be achieved by ACC, which is an energy control method, but the reproduced sound zone by ACC method may have large gap of sound pressure in it. There are several ways from previous researches attempt to resolve this “planarity” problem and reproduce plane sound field, but most of them work not directly to the planarity of sound field or need complex calculations. In this paper, we propose an easy and direct method (ACRV) to planate sound pressure without losing Acoustic Contrast and compare it with the method of previous research (ACC and ACLD.) ACRV can make more plane sound field than ACC, and also there are certain cases that ACRV perform better than ACLD.</p>

DOI： 10.1299/jsmeenv.2022.32.2113-17-04

CiNii Research

Publisher：Proceedings of the International Congress on Acoustics  

In this paper, we propose a method to reproduce different broadband sounds in different regions in the same sound space by appropriately controlling multiple sound sources. To achieve this, it is necessary to design a suitable filter that enables broadband control in the time domain. The procedure of this method is shown below. Firstly, obtain the transfer function from the sound sources to the control points at each target frequency. Secondly, the frequency characteristics of the control filter of each sound source using acoustic contrast control (ACC) based on the transfer function and find the impulse response of the control filter by performing discrete inverse Fourier transformation. Finally, by passing the input signal of a sound source through its corresponding control filter, the sound space can be divided into an acoustically bright zone and a dark zone. Simulations and experiments are conducted, and the results show that the proposed method is effective to deliver different time series signals to different regions properly. Also, we consider the cause of reverberant-like noise that occurs during control.

Scopus

Language：English   Publisher：The Japan Society of Mechanical Engineers  

<p>Eddy currents in a conductor moving in a non-uniform magnetic field in a static coordinate system are expressed as the superposition of the term by the partial derivative of the magnetic vector potential with respect to time and by the gradient of scalar potential in a stationary-conductor coordinate system. In this study, we proposed the general equation of “gradient of scalar potential is zero” condition (GSPZ condition) throughout the conductor. Additionally, under satisfying the GSPZ condition, we propose the method of obtaining the magnetic damping force from both the magnetic flux densities and the eddy currents calculated using the Biot-Savart law and Fleming's left-hand rule for the parallel-motion-type eddy current damper (GSPZ-A method). The precision of the GSPZ-A method is similar to that of the three-dimensional finite element method (3D-FEM); however, the effect of the secondary magnetic field was not considered. In this study, the GSPZ condition for the parallel-motion-type eddy current damper of a rectangular magnet and conductor of arbitrary dimensions was established. Furthermore, the GSPZ condition was applied to two types of eddy current dampers—one composed of the single square magnet and the other of the combined square magnet with oppositely aligned magnetic poles. The magnetic damping forces calculated using the GSPZ-A method were compared with those obtained from the 3D-FEM and experiments. As a result, the errors from the GSPZ-A method to 3D-FEM for the single and combined magnets were 10 and 0.4 %, respectively.</p>

DOI： 10.1299/mej.22-00280

Web of Science

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)  

Vocal fold vibration is self-excited vibration due to the interaction between the vocal folds and expired air. To analyze vocal fold vibration, several models comprising masses and springs have been proposed to date, but with those models it is difficult to determine parameter values and calculate the phenomenon in detail. Also, several researchers have analyzed vocal fold vibration using the finite element method (FEM) and the finite volume method, but such large-degree-of-freedom analyses incur high computational cost. To solve these problems, we propose a vocal fold vibration analysis model based on modal analysis. The natural modes of the vocal folds are obtained by FEM, and the air is simulated by a one-dimensional model based on Bernoulli's equation. In this approach, because the natural modes are obtained by FEM, parameters based on actual physical properties (Young's modulus, etc.) can be used, and the calculation cost is relatively low because of the modal and one-dimensional fluid analyses. To validate the proposed model, its results are compared with those from experiments on silicone vocal folds and simulations using ANSYS software, and the results correspond. Furthermore, the necessary conditions for the vocal folds to enter two particular modes of self-excited vibration are derived mathematically, and those two modes are confirmed to be dominant in the periodic solution region.

DOI： https://doi.org/10.1016/j.jsv.2021.116442

Language：English   Publishing type：Research paper (scientific journal)  

An eddy current damper comprising a magnet and a conducting plate moving perpendicularly to it is called a perpendicularmotion-type eddy current damper, whereas one with a magnet and a conducting plate moving parallel to it is called a parallelmotion-type eddy current damper. In this article, a method of using magnetic vector potentials in a stationary-conductor coordinate
system to obtain easily the damping coefficient (the A method) is proposed and applied to a perpendicular-motion-type eddy current
damper comprising a ring magnet and conducting disk. The previously proposed coil method is also applied. Because both methods
utilize the magnetic flux densities and magnetic vector potentials obtained using a circular current loop, they cannot be considered
to be the effect of the magnetic field generated by eddy currents on the damping coefficients. However, the damping coefficients were
in good agreement with those obtained using a 3-D finite element method (3-D-FEM). Hence, the effect of the secondary magnetic
field can be ignored. Moreover, the A method is as precise as the 3-D-FEM, is less complicated, and does not require an air region
and boundary conditions for computation. In addition, although the errors of the damping ratios calculated from measured data
and the A method were 17%, the error of the modified damping ratios obtained by applying the equivalent mass of the disk to the
A method decreased to 6%.

Language：English  

Acoustic absorbing materials are used in various applications to reduce noise. In air ducts and pipes, they are used to attenuate noise from devices such as fans. When an absorbing material is installed across the entire cross-section of a duct, sound wave attenuation is large, but so is pressure loss in the flow. For greater effectiveness with less acoustic absorbing material in a one-dimensional tube system, we propose a method in which layers of acoustic absorbing material are separated by air layers and we derive the transmission loss in this method. A parametric study was performed to confirm the effectiveness of the air layers and investigate characteristics of the system. The results show that the method’s effectiveness is due to the antiresonance properties of the air layers. An experiment with an acoustic tube was performed to assess the validity of the proposed method and the derived transmission loss. The experimental and numerical results for transmission loss agree well, indicating the proposed method is effective when acoustic absorbing material layers are used.

Other Link： https://doi.org/10.1016/j.apacoust.2021.107984

Language：English  

The vibration of pipes and cylindrical shells leading to noise and damage is an important engineering problem in plant systems and air conditioners, among others. To attenuate such vibration, a viscoelastic material is attached to a pipe as a damping material. Generally, the viscoelastic material covers the entire pipe to provide damping due to elongation of the material, but this requires a large amount of viscoelastic material. To overcome this problem, the approach adopted in this paper is to attach the viscoelastic material to only part of the pipe. The vibration of the pipe is then attenuated by not only the damping due to the viscoelastic material but also by the viscoelastic material acting as either a dynamic absorber or Houde damper. The disc-shaped viscoelastic material attached to the pipe is modeled as either a mass–spring–damper system or mass–damper system, and design guidelines are proposed for the material based on invariant-point theory. To assess the validity of the proposed design method, hammering tests are performed involving designed silicone attached to a pipe. The first- and second-order resonances of the pipe are attenuated by the silicone as a dynamic absorber and a Houde damper, respectively.

DOI： 10.1016/j.jsv.2020.115272

Language：English  

Vibration of pipes and cylindrical shells leading to noise and damage is an important engineering problem in plant systems and air conditioners, among others. To attenuate such vibration, a viscoelastic material is attached to pipes as a damping material. To predict the vibration reduction effect in detail, three-dimensional finite-element analysis is usually conducted considering the characteristics of the viscoelastic material, but such analysis requires considerable computation time. To overcome this problem, this study proposes added mass and added damping to address the effects of vibration of the damping material on the vibration of a pipe. By this method, one-dimensional analysis can be performed. To assess the validity of the proposed method, numerical results for the vibration of a pipe fitted with silicone obtained using the proposed method are compared with measurements from a hammering test and numerical results from three-dimensional analysis. The computational results obtained using the proposed method agree very well with the measurements and the three-dimensional numerical results. Furthermore, it is found that the vibration of the pipe is attenuated by not only the damping of the viscoelastic material but also the effect of dynamic behavior similar to that of a dynamic absorber.

DOI： 10.1016/j.jsv.2019.04.023

Language：English  

Diseases occurring near the vocal cords, such as laryngeal cancer, share the initial symptom of hoarseness of voice. The GRBAS (grade, roughness, breathiness, asthenia, strain) scale is used as an acoustic diagnostic method for these diseases, but its objectivity is not well established. Instead, more accurate diagnosis may be possible by capturing the waveform of the volume velocity at the vocal cords. The aim of this study is to enable voice disturbances to be diagnosed by identifying the sound-source waveform from voice measurements. For acoustic analysis of the vocal tract, we modeled the air inside it as concentrated masses connected by linear springs and dampers. We identified the shape of the vocal tract by making the natural frequencies of the analytical model correspond to the measured formant frequencies, and we calculated the sound-source waveform from the measured voice waveform. To assess the validity of the model, we measured actual voices and used the model to identify the vocal tract shapes and corresponding sound-source waveforms. The identified waveforms have an asymmetrical triangular form, which is a feature of actual human sound-source waveforms. Local solutions allow multiple vocal tract shapes to be identified from a single sample. However, mathematical analysis showed that these differ only in the amplitude of the sound-source waveform, which does not affect the waveform shape. Furthermore, we built an experimental device that simulates the human voice mechanism and comprises an acrylic vocal tract and a piston. We confirmed that the identified sound sources are similar to measured sound sources. We therefore conclude that our proposed methods are valid.

DOI： 10.1016/j.apacoust.2019.02.005

Language：English   Publishing type：Research paper (other academic)  

Diseases occurring near the vocal cords, such as laryngeal cancer, often cause voice disturbance as an initial symptom. As an acoustic diagnostic method for such diseases, the GRBAS (grade, roughness, breathiness, asthenia, strain) scale is widely used, but its objectivity is not well established. Instead, more accurate diagnosis may be possible by capturing the waveform of the volume velocity at the vocal cords (the vocal sound-source waveform). The aim of this study is to enable diagnosis of diseases near the vocal cords by identifying the sound-source waveform from voice measurements. In the proposed method, an analytical model of the vocal tract is used to identify the sound source. The air inside the vocal tract is modeled as concentrated masses connected by linear springs and dampers. The vocal tract shape is identified by making the natural frequencies of the analytical model correspond to the measured formant frequencies. The sound-source waveform is calculated from the analytical model by applying the measured voice (sound pressure) to the lip position of the identified vocal tract. To assess the validity of the proposed method, an experimental device was made to simulate the human voice mechanism. The device is equipped with artificial vocal cords made of a urethane elastomer that are self-excited by air flow. The sound pressure equivalent to the voice was measured using a microphone set at the lip position of the experimental device, and the flow velocity at the artificial vocal cords was measured using a laser Doppler velocimeter (LDV). To assess the model's validity, the sound-source waveform identified from the measured sound pressure was compared with the waveform measured using the LDV

Language：English  

When using the finite element method for structural–acoustic coupled analysis, the mass and stiffness matrices are not symmetric because the acoustic space is described by sound pressure and the structure is described by displacement. Therefore, eigenvalue analysis requires a long computational time. In this article, we proposed concentrated mass models for performing structural–acoustic coupled analysis. The advantage of this model is that the mass and stiffness matrices become symmetric because both the acoustic space and the membrane are described by the displacement of the mass points. Furthermore, our models do not generate spurious modes and zero eigenvalues that arise in finite element method whose variable is displacement in acoustic space. To validate the proposed models, the natural frequency obtained using the concentrated mass models is compared with the natural frequency found using finite element method. These results are in good agreement, and spurious modes and zero eigenvalues are not generated in the proposed model whose variables are sound pressure. Furthermore, we compare the proposed model with finite element method in terms of the calculation time required for the eigenvalue analysis. Because the matrices of the proposed models are symmetric, these eigenvalue analyses are faster than that of finite element method, whose matrices are asymmetric. Therefore, we conclude that the proposed model is valid for coupled analysis of a two-dimensional acoustic space and membrane vibration and that it is superior to finite element method in terms of calculation time.

DOI： 10.1177/1687814017746512

Language：Japanese  

Active noise control for two dimensional acoustic space by concentrated mass model
<p>Several adaptive feedforward control methods have been proposed in previous research on active noise control. In those methods, noise control is achieved by adding in a reverse-phase control sound of the same amplitude to noise near an error microphone. Because this method is aimed at controlling only noise near the error microphone, the control area is inherently narrow. Here, we propose an alternative method of noise control for an entire closed space. The proposed method is based on state feedback control and modeling of the acoustic space by the concentrated-mass model. The acoustic space is modeled as masses, connecting springs, and connecting dampers. Further, a loudspeaker as control source is also modeled as a mass-spring-damper system. We previously reported a method for simple one-dimensional acoustic space control. In this paper, we show the design of a control system for two-dimensional acoustic spaces. The acoustic space and loudspeakers are modeled in a concentrated-mass model, and the state feedback control system is realized as a Kalman filter with pole placement. The number of degrees of freedom is reduced by using modal analysis, which reduces the computation time of the controller. Experiments and numerical simulation of the coupled system were conducted to confirm the validity of the analysis model. Noise in the acoustic space was experimentally controlled, with the finding that noise in the entire acoustic space was reduced around the resonance frequencies. Furthermore, the limit of the control effect are considered within the proposed system.</p>

DOI： 10.1299/transjsme.17-00305

Language：English  

In this paper, a method for designing a robust internal model control (IMC) structured feedback active noise controller is considered. For feedback active noise control (ANC) systems, the IMC structure is preferred because of the possibility of applying an adaptive filter in the controller and the simplicity of satisfying the stability if an accurate secondary path model is available. In practice, however, model uncertainties exist so that the robust stability of the controller must be considered during the controller design process. Moreover, the waterbed effect for feedback control of a time-delayed system will cause noise amplification (NA) at some frequencies out of the target band of control. Against these problems, this paper proposes a controller design method in which a constraint for the control filter coefficients is found to ensure the robust stability and limit the NA caused by the waterbed effect to within a given value. In comparison with the design process in the frequency domain, this method can use an adaptive algorithm to obtain a robust controller solution in the time domain. Once the time domain constraint has been obtained, it can also be used in the online IMC feedback ANC system. Computer simulations and experiments in an anechoic chamber are performed to validate the method. The results indicate that this method is effective for the design of a robust controller with constrained NA.

DOI： 10.3397/1/376344

Language：Japanese  

Development of measurement technique of living body flexibility by indentation test using concentrated mass model
Palpation is an important diagnostic technique in medicine. However, it is subjective, and successful diagnosis depends on the skill and experience of the doctor. Therefore, a quantitative method for measuring the hardness of the living body and detecting abnormal tissue is desirable. In this paper, we propose a concentrated mass model of the body to analyze its motion in an indentation test. The model consists of masses, connecting springs, connecting dampers, base support springs, and base support dampers. The mass is the mass of the elastic body, the connecting spring is derived from the normal stress, and the base support spring is derived from the shear stress. Furthermore, we develop a method to measure the Youngs modulus and the position of abnormal tissue with the model when a column contactor is pressed into the body. To confirm the validity of the method, we measured the Youngs modulus of silicone. The measurement results by the proposed method agreed with the value obtained with a parallel disk rotary rheometer. Moreover, our method gave accurate values for the Youngs modulus of the second layer of two-layered silicone and the distance from the surface to the second layer. These results confirmed that our method is capable of measuring the Youngs modulus of the soft materials and the boundary depth in two-layered objects.

DOI： 10.1299/transjsme.14-00480

Language：Japanese  

Active noise control based on state feedback by concentrated mass model (Model based control for one-dimensional acoustic space and loudspeaker)
We herein propose a new model-based control method, in place of traditional adaptive control, for a low-frequency noise problem in a closed space. The proposed control method is based on state feedback control and a model of the acoustic space obtained by the concentrated mass model. Thus, we can control noise in the entire space. According to the concentrated mass model, the acoustic space is modeled as masses, connecting linear springs, connecting dampers, and base support dampers. Furthermore, a loudspeaker, as a control source, is also modeled by a mass, a spring, and a damper. In the present paper, as a first step, we constructed a coupled analysis model of a one-dimensional acoustic space and the loudspeaker. We designed the model-based control system for the standing sound wave in the low-frequency band. Specifically, we realized a state feedback control system based on a Kalman filter and pole placement. Modal reduction using modal analysis is conducted to reduce the computation time of the controller. Then, we conducted experiments and a numerical simulation of the one-dimensional sound tube to confirm the validity of the analysis model. Moreover, we perform an experiment to control the noise in the sound tube. The noise is reduced around the resonance frequency in the entire space. Therefore, the proposed method is valid for noise control in a closed space.

DOI： 10.1299/transjsme.14-00485

Language：English  

Language：English  

Language：English  

Language：English  

Language：English  

Language：English  

Language：English  

Language：English  

Language：Japanese  

Language：English  

Language：Japanese  

Language：English  

Language：Japanese  

Language：Japanese  

Event date： 2013.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyushu Sangyo University   Country：Japan  

Event date： 2013.8

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyushu Sangyo University   Country：Japan  

Event date： 2012.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Kuala Lumpur   Country：Malaysia  

Event date： 2011.9

Language：Others   Presentation type：Oral presentation (general)  

Venue：Osaka   Country：Japan  

Event date： 2009.8

Language：Others   Presentation type：Oral presentation (general)  

Venue：Ottawa, Ontario   Country：Canada  

Event date： 2009.8

Language：Others   Presentation type：Oral presentation (general)  

Venue：Ottawa, Ontario   Country：Canada  

Event date： 2008.10

Language：Others   Presentation type：Oral presentation (general)  

Venue：Shanghai, Chaina   Country：Japan  

Event date： 2007.8

Language：Others   Presentation type：Oral presentation (general)  

Venue：札幌市   Country：Japan  

Language：Others   Presentation type：Oral presentation (general)  

Venue：Honolulu, Hawaii   Country：United States  

Language：Others   Presentation type：Oral presentation (general)  

Country：Singapore  

Language：Others   Presentation type：Oral presentation (general)  

Venue：Southampton   Country：United Kingdom  

Language：Others   Presentation type：Oral presentation (general)  

Venue：Beijing   Country：China  

Event date： 2023.7

Language：English   Presentation type：Oral presentation (general)  

Venue：Matsue, Shimane   Country：Japan  

Event date： 2019.7

Language：English  

Venue：Montreal   Country：Canada  

Diseases occurring near the vocal cords, such as laryngeal cancer, often cause voice disturbance as an initial symptom. As an acoustic diagnostic method for such diseases, the GRBAS (grade, roughness, breathiness, asthenia, strain) scale is widely used, but its objectivity is not well established. Instead, more accurate diagnosis may be possible by capturing the waveform of the volume velocity at the vocal cords (the vocal sound-source waveform). The aim of this study is to enable diagnosis of diseases near the vocal cords by identifying the sound-source waveform from voice measurements. In the proposed method, an analytical model of the vocal tract is used to identify the sound source. The air inside the vocal tract is modeled as concentrated masses connected by linear springs and dampers. The vocal tract shape is identified by making the natural frequencies of the analytical model correspond to the measured formant frequencies. The sound-source waveform is calculated from the analytical model by applying the measured voice (sound pressure) to the lip position of the identified vocal tract. To assess the validity of the proposed method, an experimental device was made to simulate the human voice mechanism. The device is equipped with artificial vocal cords made of a urethane elastomer that are self-excited by air flow. The sound pressure equivalent to the voice was measured using a microphone set at the lip position of the experimental device, and the flow velocity at the artificial vocal cords was measured using a laser Doppler velocimeter (LDV). To assess the model's validity, the sound-source waveform identified from the measured sound pressure was compared with the waveform measured using the LDV

Event date： 2018.7

Language：English  

Venue：Hiroshima   Country：Japan  

Laryngeal cancer and voice disturbance share the initial symptom of hoarseness of voice. By analyzing changes in the voice, these diseases might be diagnosed. Because it is important to detect these diseases as early as possible, there is demand for a simple and highly accurate diagnostic method. The GRBAS (grade, roughness, breathiness, asthenia, strain) scale is used as an acoustic diagnosis method for these disorders but its objectivity is not well established. Instead, more accurate diagnosis is possible by capturing the waveform of the flow velocity at the vocal cords. The aim of this study was to enable diagnosis of laryngeal cancer and voice disturbance by identifying the sound-source waveform from voice measurements. For acoustic analysis of the vocal tract, we modeled the air in the vocal tract as concentrated masses connected by linear springs and dampers. The vocal tract shape was identified by making the natural frequencies of the analytical model correspond to the measured formant frequencies. The sound-source waveform was calculated from the measured voice waveform. To assess the validity of the model, we measured actual voices and used the model to identify the vocal tract shapes and corresponding sound-source waveforms. The identified waveforms were similar to the Rosenberg wave, which is an approximation of the actual vocal sound-source waveform. Because of the influence of local solutions, multiple vocal tract shapes could be identified from a single sample. However, mathematical analysis showed that these differed in amplitude of sound-source waveform only, which does not affect the shape of the waveform. From this, we conclude that our proposed methods are valid.

Event date： 2017.8

Language：English  

Venue：Hong Kong   Country：China  

Several adaptive feedforward control methods have been proposed in previous research on active noise control. In those methods, noise control is achieved by adding in a reverse-phase control sound of the same amplitude to noise near an error microphone. Because this method is aimed at controlling only noise near the error microphone, the control area is inherently narrow. Here, we propose an alternative method of noise control for an entire closed space. The proposed method is based on state feedback control and modeling of the acoustic space by the concentrated-mass model. The acoustic space is modeled as masses, connecting springs, connecting dampers, and base support dampers. Further, a loudspeaker as control source is also modeled as a mass-spring-damper system. We previously reported a method for simple one-dimensional acoustic space control. In this paper, we show the design of a control system for two-dimensional acoustic spaces. The acoustic space and loudspeakers are modeled in a concentrated-mass model, and the state feedback control system is realized as a Kalman filter with pole placement. The number of degrees of freedom is reduced by using modal analysis, which reduces the computation time of the controller. Experiments and numerical simulation of the coupled system were conducted to confirm the validity of the analysis model. Noise in the acoustic space was experimentally controlled, with the finding that noise in the entire acoustic space was reduced around the resonance frequencies. Furthermore, the theoretically the limit of the control effect are considered within the proposed system.

Event date： 2016.7

Language：English  

Venue：Athens   Country：Greece  

When using the finite element method (FEM) for a structural-acoustic coupled analysis, the mass and stiffness matrices are not symmetric because the acoustic space is described by sound pressure and the structure is described by displacement. Therefore, eigenvalue analysis takes a long time. In our previous studies, we have proposed a concentrated mass model for in performing structural-acoustic coupled analysis. The advantage of this model is that the mass and stiffness matrices become symmetric because both the acoustic space and the membrane are described by the displacement of the mass points. However, some physically meaningless modes, such as spurious modes and zero eigenvalues, arise with this model. In this paper, we propose a new concentrated mass model that does not generate the spurious modes and zero eigenvalues. This model can be used to analyze a coupled system of a two-dimensional acoustic space and a membrane. The mass points of the new model are placed at the sides of elements rather than at nodal points. To confirm the validity of the proposed model, the natural frequency obtained by using the concentrated mass model is compared with the natural frequency found by using FEM. These results are in good agreement, and spurious modes and zero eigenvalues are not generated in the proposed model. Furthermore, we compared the proposed model with FEM in terms of the time required for the eigenvalue analysis. Because the mass and stiffness matrices of the proposed model are symmetric, its eigenvalue analysis is faster than that of FEM, whose matrices are asymmetric. Therefore, we conclude that the proposed model is valid for coupled analysis of a two-dimensional acoustic space and membrane vibration, and that it is superior to FEM in terms of calculation time.

Event date： 2016.7

Language：English  

Venue：Athens   Country：Greece  

This paper presents an active noise control (ANC) approach to reducing noise in a certain area by controlling the sound pressure at a local point based on the concept of wavefront synthesis. Multi-input and multi-output (MIMO) ANC systems can achieve the global control of noise. However, the computational complexity of the control algorithm and the complicated hardware configuration limit the use of MIMO systems. In order to simplify the system structure, a concept of dividing a global ANC system into sub-systems according to the control objectives is considered in this paper. One sub-system is to reproduce the wavefront of the incident noise into the target area, and the other one is to tune the amplitude and phase of the reproduced control sound wavefront. The first system objective can be realized by a sound field reproduction method, and the latter one can be implemented by a single-input and single-output (SISO) ANC system. Based on this concept, a locally global ANC system using a loudspeaker array that reproduces planar waves according to the incident angle of the noise is proposed. Numerical simulations are conducted to verify the effectiveness of the system. The results show that the proposed system can effectively reduce the noise in the target area regardless of the incident angle of the noise.

Event date： 2014.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Melbourne   Country：Australia  

Event date： 2014.11

Language：English  

Venue：Melbourne   Country：Australia  

In this paper, a hybrid active noise barrier (ANB) with sound masking capability is considered. To protect the speech privacy, several sound masking techniques have been developed. However, these sound masking techniques based on the superposition of the masker and original sound will lead to increase in the loudness of the sound after masking. Against this problem, this paper proposes a soundproof system which combines an ANB with a sound masking system. The ANB applies a new type of hybrid active noise control (ANC) system, which can reduce the noise diffraction and the noise propagated to the ear positions of the people behind the ANB simultaneously, to attenuate the conversation sound. Consequently, the required volume of the masker sound will decrease because of the smaller loudness of the original conversation sound in the control area. The sound masking system applies a method which can generate masker based on the frequency properties of the original sound. Several simulations are carried out to investigate the sound attenuation and sound masking performance of this system, and the results show that comparing with the traditional sound masking system, the proposed system needs smaller masker sound to achieve the sound masking effect.

Event date： 2014.11

Language：English  

Venue：Melbourne   Country：Australia  

In the finite element method of a structural-acoustic coupled analysis, the mass matrix and the stiffness matrix are not symmetrical. Therefore, the modal analysis cannot be applied directly to the coupled problem. In our previous study, a concentrated mass model was proposed to analyze a two-dimensional acoustic analysis. The model consists of the masses, the connecting springs. It is very easy to couple the structure and acoustic field by the concentrate mass model. Furthermore, the mass matrix and the stiffness matrix are symmetrical. In this paper, we propose a concentrated mass model to perform a coupled analysis of a two-dimensional acoustic and a membrane vibration. And we propose a coupling method to arrange of the masses of the air near the membrane. To confirm the validity of the proposed model, the natural frequency obtained by the concentrated mass model is compared with the natural frequency by the modal coupling method. These results are in good agreement. Therefore, it is concluded that the proposed model is valid for the coupled analysis of an acoustic and a vibration analysis.

Event date： 2014.11

Language：English  

Venue：Melbourne   Country：Australia  

We herein propose a new model-based control method, in place of traditional adaptive control, for a low-frequency noise problem in a closed space. The proposed control method is based on state feedback control and a model of the acoustic space obtained by the concentrated mass model. Thus, we can control noise in the entire space. According to the concentrated mass model, the acoustic space is modeled as masses, connecting linear springs, connecting dampers, and base support dampers. Furthermore, a loudspeaker, as a control source, is also modeled by a mass, a spring, and a damper. In the present paper, as a first step, we constructed a coupled analysis model of a one-dimensional sound field and the loudspeaker. We designed the model-based system for the standing sound wave in the low-frequency band. Specifically, we realized a state feedback control system based on a Kalman filter and pole placement. Modal reduction using modal analysis is conducted to reduce the computation time of the controller. Then, we conducted experiments and a numerical simulation of the one-dimensional sound tube to confirm the validity of the analysis model. Moreover, we perform an experiment to control the noise in the sound tube. The noise is reduced around the resonance frequency in the entire space. Therefore, the proposed method is valid for noise control in a closed space.

Event date： 2014.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Melbourne   Country：Australia  

Event date： 2013.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyushu Sangyo University   Country：Austria  

Event date： 2013.9

Language：English  

Venue：Innsbruck   Country：Austria  

FDTD method and CIP method are used for an acoustic analysis in time domain. However, these methods do not take into account a sound attenuation from viscosity. In our study, we propose a concentrated mass model which consists of spring-mass-damper system to perform a two-dimensional acoustic analysis. The dampers of this model consider viscosity of air. In this paper, we derive mass, connecting springs, connecting dampers, and base support dampers. The characteristic of the connecting spring is derived from the condition of adiabatic change of air, and the connecting damper is derived from the normal stress. To confirm the validity of the proposed model, the numerical results obtained by the concentrated mass model are compared with the theoretical value of the traveling wave, and with the theoretical value of the natural frequency. All numerical computational results agree very well with the theoretical values. Therefore, it is concluded that the proposed model is valid for the two-dimensional acoustic analysis.

Event date： 2013.9

Language：English  

Venue：Innsbruck   Country：Austria  

Larynx cancer or pulmonary problems cause the initial symptoms such as hoarse voice. There is a possibility of diagnoses of the affected area by analyzing these changes of voice. In this study, our purpose is to enable diagnoses of larynx cancer or pulmonary problems by an acoustic analysis model inside of the vocal tract. As a first step, we aimed to establish an acoustic analysis method in the vocal tract, and identification method of vocal tract shapes and vocal sound source waveforms. In this paper, we modeled the air in the vocal tract as a concentrated mass model that consists of masses, connecting linear springs, connecting dampers, and base support dampers. And we make an acoustic analysis model in the vocal tract. Then we identified the vocal tract shapes by using the Levenberg-Marquardt method, and analyzed vocal sound source waveforms by using the transfer matrix method from the measured voice wave. And we simulated a speech production by the analyzed sound source. The identified vocal tract shapes are valid and the analyzed vocal sound source waveforms are similar to the Rosenberg wave. The speech production results are clear voices. Then, we conclude our proposed methods are valid.

Event date： 2013.9

Language：English   Presentation type：Oral presentation (general)  

Venue：Kyushu Sangyo University   Country：Austria  

Event date： 2012.11

Language：English   Presentation type：Oral presentation (general)  

Venue：Kuala Lumpur   Country：Malaysia  

Event date： 2011.9

Language：English  

Venue：Osaka   Country：Japan  

In this paper, a kind of active noise barrier (ANB) using active noise control (ANC) technique to improve noise attenuation in low frequencies is proposed. The ANB consists of an ordinary noise barrier, three active noise control units (ANCU) and a DSP (TMS 320C6713 DSK). Feedback ANC system is used in the ANCUs. In order to achieve higher noise attenuation, fast transversal filter adaptive algorithm is introduced into the feedback ANC system. An investigation into the acoustic boundary generated by an ANCU is conducted. It is shown that the acoustic power flow around the surface of an ANCU reduced when control is turned on. Also, numerical and experimental study on an active noise barrier is conducted. As a result, the active noise barrier shows better noise attenuation performance in low frequencies.

Event date： 2011.1

Language：Others   Presentation type：Symposium, workshop panel (public)  

Venue：熊本大学   Country：Japan  

Event date： 2010.11

Language：English  

Venue：Glendale, AZ   Country：United States  

This paper treats a disturbance cancellation problem for minimizing the effects of reaction forces on position accuracy of a clean-room robot applied with magnetic bearings. The robot is composed of a main body and a ladder arm, and moves without friction at joints owing to magnetic support. The support stiffness is, however, weaker than the conventional bearings, and the ladder arm moves in reaction to rotary motion of the main body. A feedforward controller is designed to compensate the effects of the reaction forces, and implemented successfully to reduce the transverse displacements of the ladder arm when the main body rotates.

Event date： 2010.11

Language：Others   Presentation type：Oral presentation (general)  

Venue：Glendale, AZ   Country：United States  

Event date： 2009.8

Language：English  

Venue：Ottawa, ON   Country：Canada  

On active noise control in 3-dimensional acoustic field, a control effect reduces when an evaluation point moves. Against this problem, we proposed control with filter map. In this algorithm, a control area is divided into small grids. Adaptive filters are accumulated and corresponding to the node. The controller is updated from the accumulation. Effectiveness of this algorithm was shown in simulations. In this paper, the validity of this algorithm is shown in several simulations and experiments in an anechoic chamber. The evaluation point moves 0.4m at the speed of 0.45m/s in experiment. A CCD camera detects a position of the point. From the experimental results, it is shown that the effectiveness of the proposed algorithm is 10dB more than the that of the direct adaptive algorithm.

Event date： 2008.6 - 2008.7

Language：English  

Venue：Cambridge   Country：United Kingdom  

This paper presents a design of a magnetic-bearing system well suited for a smaller rotating machine. The system contains two 3-pole active radial bearings and an optimal passive axial bearing. The effects of number of stator poles are investigated on the rotor outside diameter for an outer-rotor type of radial bearing, and the investigation reveals that 3-pole bearings yield the smallest rotor outside diameter for a stator-eore diameter less than 50 mm. The structural configuration of the axial bearing is also optimized to have the largest support stiffness. Those radial and axial bearings are integrated in a homopolar configuration to yield a smaller magnetic-bearing system.

Event date： 2006.12

Language：English  

Venue：Honolulu, HI   Country：United States  

In order to perform acoustic analysis with sufficient accuracy, the method of treating sound absorption characteristics is important. Modeling theories using flow resistance or complex density / complex sound velocity are generally used in the modeling methods of porous materials. However, since it is difficult to find out necessary material characteristic for prediction of the sound absorption characteristic, acoustic characteristics of sound absorption material may be unable to be predicted. In this research, an easy modeling method of sound absorption material will be proposed for analyzing the 3-dimensional acoustic field that has a sound absorption material. Therefore, an experiment was conducted on the sound tube that has a sound absorption material. The validity of a simple modeling method of sound absorption material is verified by comparison of the experimental result and the calculated result. And the simple modeling method will be applied to automatic water supply equipment. An optimal arrangement of the sound insulation / absorption material was calculated by the numerical analysis. Consequently, the noise could be reduced by 4dB(A). In addition, structural acoustic coupled analysis is due to be performed to the noise reduction in consideration of the sound absorption characteristic of material of automatic water supply equipment.

Event date： 2006.12

Language：English  

Venue：Honolulu, HI   Country：United States  

Considering about practical use of active noise control in 3dimensional sound field, it is difficult to obtain characteristic of a secondary path (acoustic path from the secondary source to the error microphone) beforehand. In this paper, a FTF algorithm that has fast converging property is newly introduced to a direct adaptive algorithm which does not need the secondary path characteristic beforehand. A numerical simulation is carried out with a sound field that the error path changes during control. Experiments are also carried out. The effectiveness of the proposed algorithm is shown through both the simulations and the experiments.

Event date： 2006.10

Language：English  

Venue：Busan   Country：Korea, Republic of  

Self-sensing active magnetic bearing is designed by a new approach. The approach aims to solve the observer bias problem by introducing a Kalman filter. In order to verify the validity of the approach, a Kalman filter is designed for a three-pole homopolar magnetic bearing and used to estimate the radial displacement and velocity of the rotor. The electric current is driven by a linear power-amplifier circuit to flow through the coils, and the coil terminal voltage is passed through an analog first-order low-pass filter with a cut-off frequency of 100 Hz. The designed Kalman filter uses the filtered coil-voltage and the controller inputs as an input for calculating the estimate. The unobservable bias is estimated as an unknown state, and the Kalman-filter estimates are numerically simulated by the measured input/output data. The results show that the bias is successfully estimated to overlap the estimated displacement to its measurement.

Event date： 2005.9

Language：English  

Venue：Long Beach, CA   Country：United States  

A clearance configuration of fluid-film journal bearings is optimized in a sense of enhancing the stability of a full circular bearing at high rotational speeds. A performance index is chosen as the sum of the squared whirl-frequency ratios over a wide range of eccentricity ratios, and a Fourier series is used to represent an arbitrary configuration of fluid-film bearings. An optimization problem is then formulated to find the Fourier coefficients to minimize the index. The whirl-frequency ratio is inversely proportional to the stability threshold speeds of a Jeffcott rotor. The short bearing approximation is used to simplify a mathematical model that describes a pressure distribution developed in a fluid-film bearing. The designed bearing cannot destabilize the Jeffcott rotor at any high rotating speed subject to the short-bearing assumption and significantly reduces the size of the unstable region for a finite-length bearing with a small length-to-diameter ratio.

Event date： 2000.2 - 2000.3

Language：English  

Venue：Santa Clara, CA, USA   Country：Other  

This paper proposes a new approach to reducing an effect of floor vibration on an image of a scanning electron microscope. An image-shifting coil is used to move the electron probe in order to cancel undesirable motion of a specimen due to the floor vibration. The floor vibration is structurally transmitted through the microscope and detected by two acceleration sensors at the root of the specimen chamber of the microscope. The outputs of the acceleration sensors are fed forward into a controller to move the electron probe by the image-shifting coil. The feed-forward controllers are designed in two ways. The first one is based on a transfer function from the sensor outputs to the relative displacement of a specimen to the electron probe being at rest. The microscope is put on a table attached to a shaker. Sinusoidal excitation tests are done many times to estimate the transfer functions from vibrating images of a micro scale. Moreover, the second controller is designed by manually amplifying and delaying the sensor outputs so as to minimize amplitude of the vibrating images on a CRT. Those two controllers are implemented as a digital filter running on a digital signal processor.

Event date： 1998.8

Language：English  

Venue：Boston   Country：United States  

This paper treats the attitude control of a space robot using the fact that a free-flying space robot can reorient its attitude only by moving the manipulators. We solve an optimal control problem formulated in a more general way than those of the problems to have been solved so far. That is, our approach can afford to solve the case where the initial and final postures of the manipulators are different and where the solution could not be a smooth and continuous function of time. The optimal control problem is discretized by the rectangular rule into a mathematical programming problem to be solved by the periodically preconditioned conjugate gradient-restoration algorithm. A space-robot model with a multi-link manipulator is used to exemplify the present approach.

Event date： 1996.7

Language：English  

Venue：San Diego   Country：United States  

In this paper, we put forth the idea that a wave—based controller can be realized by using a noisy modal model. This idea is based on the fact that a wave-based input—output relation may be interpreted as that of a usual modal model contaminated with colored measurement noise. Specifically, an identical controller can be derived from models based on either a traveling wave or standing one on a flexible structure. In general, we can design a controller in terms of a regulator and a Kalman filter in a linear stochastic system. Since the Kalman filter contains unknown dynamics of the colored noise in the present system, this dynamics can be selected to realize the wave-based controllers. Furthermore, we design a controller for vibration suppression of a flexible beam to investigate the validity of this idea numerically. The results show that a modal compensator agrees with the wave-based one well, and yields a new interpretation of a wave-based controller.

Event date： 1989.7

Language：English  

Venue：Honolulu, HI, USA   Country：Other  

In order to control vibration, many mechanical structures have recently begun using active elements. Up to now, in cases of designing such structures, structural analysis and design of the controller were carried out separately, and a controller was apt to become too complex. This paper investigates a design method that can use both vibration analysis and the controller design. This method is to design a controller by using both the transfer functions of the controller and whole structure.

Event date： 1989.7

Language：English  

Venue：Honolulu, HI, USA   Country：Other  

In order to control vibration, many mechanical structures have recently began using active elements. Up to now, in cases of designing such structures, structural analysis and design of the controller were carried out separately, and a controller is apt to become too complex. This paper investigates a design method that can use both vibration analysis and the controller design. This method is to design a controller by using both the transfer functions of the controller and whole structure.

Language：Others   Presentation type：Oral presentation (general)  

Venue：Honolulu, Hawaii   Country：United States  

Language：Others   Presentation type：Oral presentation (general)  

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Venue：Fukuoka   Country：Japan  

Language：Others   Presentation type：Oral presentation (general)  

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Venue：Montreux   Country：Switzerland  

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Venue：Jeju   Country：Korea, Republic of  

Language：Others   Presentation type：Public lecture, seminar, tutorial, course, or other speech  

Venue：KOREA MARITIME UNIVERSITY   Country：Korea, Republic of  

Language：Others   Presentation type：Oral presentation (general)  

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Venue：Prague   Country：Czech Republic  

Language：Others   Presentation type：Oral presentation (general)  

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Venue：Daejeon   Country：Korea, Republic of  

Language：Others   Presentation type：Oral presentation (general)  

Venue：Torino   Country：Italy  

Language：Others   Presentation type：Oral presentation (general)  

Venue：Busan   Country：Korea, Republic of  

Language：Japanese  

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Type：Peer review 

Number of peer-reviewed articles in foreign language journals：1

Number of peer-reviewed articles in Japanese journals：3

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Number of peer-reviewed articles in foreign language journals：2

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Number of peer-reviewed articles in foreign language journals：2

Number of peer-reviewed articles in Japanese journals：3

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Number of participants：460

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Number of peer-reviewed articles in foreign language journals：4

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Number of peer-reviewed articles in foreign language journals：2

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Proceedings of International Conference Number of peer-reviewed papers：5

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Number of peer-reviewed articles in foreign language journals：2

Number of peer-reviewed articles in Japanese journals：2

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