Kyushu University Academic Staff Educational and Research Activities Database
Researcher information (To researchers) Need Help? How to update
Yukihiko Yamagata Last modified date:2018.06.11

Associate Professor / Electrical Process Engineering
Department of Advanced Energy Science and Engineering
Faculty of Engineering Sciences


Graduate School
Undergraduate School


E-Mail
Homepage
http://www.asem.kyushu-u.ac.jp/ep/ep01/jp/index.html
Ionized Gas Dynamics Laboratory .
http://plasma.ence.kyushu-u.ac.jp/rc-plasma/
Institute for Ionized Gas and Laser Research .
Phone
092-583-7605
Fax
092-571-8013
Academic Degree
Doctor of Engineering
Field of Specialization
Plasma Science and Technology
Research
Research Interests
  • Optimization of electric field distribution in a new refrigerator system for keeping freshness of perishable foods
    keyword : electric field, freshness, cold chain, perishable food,
    2017.04Spatial and temporal measurements of Ba atoms in a fluorescent lamp using laser-indeced fluorescence method.
  • Development of measurement technique for surface roughness of substrate material in thermal spraying process
    keyword : thermal spraying, surface roughness, laser measurement, simple and compact system
    2017.04Spatial and temporal measurements of Ba atoms in a fluorescent lamp using laser-indeced fluorescence method.
  • Development of measurement technique for temperature and strain of semiconductors having a wide band gap using pulsed-laser scattering system
    keyword : pulsed laser, LED, LD, wide band gap, semiconductor, junction, strain, remote measurement
    2016.04Spatial and temporal measurements of Ba atoms in a fluorescent lamp using laser-indeced fluorescence method.
  • Development of measurement system for particle parameters in thermal spraying process
    keyword : thermal spraying, particle, temperature, velocity, remote measurement
    2014.04Spatial and temporal measurements of Ba atoms in a fluorescent lamp using laser-indeced fluorescence method.
  • Development of temperature measurement method for the junction of working LED using pulsed-laser system
    keyword : pulse laser, junction temperature, LED, remote measurement
    2011.04Spatial and temporal measurements of Ba atoms in a fluorescent lamp using laser-indeced fluorescence method.
  • Investigation of properties of atmospheric micro discharge using laser diagnostics
    keyword : atmospheric micro discharge, dielectric barrier discharge, electron temperature, electron density, laser diagnostics
    2006.04Investigation of properties of atmospheric micro discharge using laser diagnostics.
  • Development of generation method for uniform and large-area VHF plasmas
    keyword : large-area VHF plasma, uniform, thin film solar cell
    2010.04.
  • Simultaneous decomposition of NOx and particulate matter in deisel exhaust gas using non-thermal atmospheric discharge
    keyword : nitric oxides, diesel particulate matter, diesel exhaust gas, simultaneous decomposition, zeolite, non-thermal atmospheric discharge
    2001.05Simultaneous decomposition of NOx and particulate matter in deisel exhaust gas using non-thermal atmospheric discharge.
  • Development of effective decomposition technique of environmentally hazardrous materials with low concentration using atmospheric dielectric barrier discharge combined with adsorption/localization method
    keyword : hazardrous materials, VOC, NOx, low concentration, Zeolite, adsorption, honeycomb, atmospheric pressure, dielectric barrier discharge
    1995.04~2016.03Aftertreatment of environmentally hazardrous materials using atmospheric dielectric barrier discharge combined with adsorption/localization technique.
  • Spatial and temporal measurements of Ba atoms in a fluorescent lamp using laser-indeced fluorescence method
    keyword : fluorescent lamp, Ba, laser-indeced fluorescence, electrode temperature, low pressure glow discharge plasma
    2004.04~2016.03Spatial and temporal measurements of Ba atoms in a fluorescent lamp using laser-indeced fluorescence method.
  • Measurement of negative ion density in plasmas using laser Thomson scattering
    keyword : negative ion density, electron density, low pressure discharge plasma, laser Thomson scattering
    2001.05~2009.03Development of measurement method of density of negative ion in plasmas using laser Thomson scattering.
Academic Activities
Papers
1. M. Horiuchi, Y. Yamagata, S. Tsutsumi, K. Tomita, Y. Manabe, The Development of a System for Measuring the Junction Temperatures of Multiple LEDs on a Package Simultaneously by Using Pulsed-laser Raman Scattering, Journal of Science and Technology in Lighting, 10.2150/jstl.IEIJ160000584, 41, 101-107, Online ISSN : 2432-3233
Print ISSN : 2432-3225, 2017.11, This paper details a novel method consisting of employing a pulsed-laser Raman scattering technique to estimate junction temperatures of several LED chips arranged in a straight line on a phosphor-less blue-LED package and a phosphor-resin coated blue-LED package. By using a sheet-shaped irradiation pattern, each of the GaN-E2H Raman spectra from several chips mounted straight on a phosphor-less blue LED package was observed at the same time and the junction temperature of each chip was estimated successfully by means of each Raman shift during operation despite the existence of strong LED emission. In addition, the GaN-E2H Raman signal from the phosphor-resin coated blue-LED was observed for the first time by using 633 nm laser to reduce the negative influence from the phosphor and light diffusing substances in the resin. It is concluded that this technique would be a useful method for a remote and standard system for 2D mapping of the junction temperatures of blue-LED packages..
2. Y. Kawaguchi, N. Kobayashi, Yukihiko Yamagata, F. Miyazaki, M. Yamasaki, J. Tanaka, K. Muraoka, Optical monitoring systems for thermal spray processes
Droplets behavior and substrate pre-treatments, Journal of Instrumentation, https://doi.org/10.1088/1748-0221/12/11/C11031, 12, 11, 2017.11, Thermal spray is a technique to form molten droplets using either plasma- or combustion-heating, which impinge upon substrates to form coating layers for various purposes, such as anti-corrosion and anti-wear layers. Although it is an established technique having a history of more than a century, operations of spray guns together with preparing suitable substrate surfaces for obtaining good coating layers still rely on experienced technicians. Because of the necessity of meeting more and more stringent requirements for coating quality and cost from customers, there has been a strong need to try to monitor spray processes, so as to obtain the best possible spray coating layers. The basic requirements for such monitoring systems are ∗reasonably cheap, ∗easy operation for laypersons, ∗easy access to targets to be investigated, and ∗an in-situ capability. The purpose of the present work is to provide suitable optical monitoring systems for (1) droplets behavior and (2) substrate pre-treatments. For the former (1), the first result was already presented at the 17th laser-aided plasma diagnostics meeting (LAPD17) in 2015 in Sapporo, and the results of its subsequent applications into real spray environments are shown in this article in order to validate the previous proposal. Topic (2) is new in the research program, and the proof-of-principle experiment for the proposed method yielded a favorable result. Based on this positive result, an overall strategy is being planned to fulfill the final objective of the optical monitoring of substrate pre-treatments. Details of these two programs (1) and (2) together with the present status are described..
3. Makoto Horiuchi, 山形 幸彦, Shin-ichi Tsutsumi, 富田 健太郎, Yoshio Manabe, Development of junction temperature estimation system for light-emitting LED using pulsed-laser Raman scattering, Journal of Solid State Lighting, 10.1186/s40539-015-0026-9, Vol. 2, 7, 1-7, 2015.07, [URL], A new method by using a pulsed-laser Raman scattering technique was employed to
estimate junction temperature of a fluorescence-resin-less blue-LED package.
Temperature dependent Raman shift of E2
H mode of GaN layer in the blue-LED were
obtained and were in good agreement with the experimental data published by the
other researchers. This technique was applied to estimation of a junction temperature
of the light-emitting blue-LED. The junction temperature was successfully estimated
even under the strong stray light and LED light emission. It is considered that the
proposed technique would be a remote and standard system for measuring the
junction temperature of light-emitting white-LEDs.
4. Y. Yamagata, K. Niho, T. Jono, K. Muraoka, Simultaneous decomposition of diesel particulate material and NOx using dielectric barrier discharge, Journal of Advanced Oxidation Technologies, Vol. 9, No. 2, pp. 134-138, 2006.06.
5. H. Naitou, Y. Sakurai, Y. Tauchi, O. Fukumasa, M. Yagi, Y. Yamagata, K. Uchino, K. Muraoka, Simulation of photo-detached electrons in negative ion plasmas, Plasma Physics and Controlled Fusion, 10.1088/0741-3335/46/8/004, 46, 8, 1217-1230, Vol. 46, pp. 1217-1230, 2004.07.
Presentations
1. 堀内 誠, 山形幸彦, 富田健太郎, 真鍋由雄, Pulsed-laser Raman scattering for simultaneous estimation of junction temperatures in a LED module, BIT’s 6th Annual World Congress of Advanced Materials-2017, 2017.06, For LED and other semiconductor power devices in which integration and high current operation are required, the efficiency, the lifetime, and the operational stability degrade remarkably resulting from the temperature rise of the junction of these devices. Therefore, in order to fabricate a high quality device, junction temperature measurement of the device in operation, and the heat radiation design of the whole device based on the experimental results are primary important. In this study a novel method by using a pulsed-laser Raman scattering technique was employed to estimate junction temperatures of a phosphor-less blue-LED module. Observation of GaN-E2H Raman spectra was done successfully and temperature dependent Raman spectra of GaN were detected. This technique was applied to simultaneous estimation of the junction temperatures of the several chips in the phosphor-less blue LED module in operation. It is concluded that this technique would be a useful method for remoteness and simultaneous multipoint measurement, which lead to 2D mapping of the junction temperature of a white-LED in which several chips are integrated..
2. 山形 幸彦, Pulsed-laser Raman scattering for measurement of junction temperature of white-LED, the 5th International Conference and Exhibition on Lasers, Optics and Photonics, 2016.11, Recently, the characteristic of a light emitting diode (LED) has been improved dramatically, and the application to illumination is recognized as one of the most important issue to the manufacturers. It is well known that the efficiency, the output power, the life-time and the reliability of LED degrade with a temperature rise of the junction of LED. In order to fabricate a high quality LED module for illumination, it is necessary to keep the junction temperature low by improving the characteristic of LED chip itself, or by effective heat removal through a heat radiation design of the module. Therefore, it is strongly required to establish a standard method to measure the junction temperatures in LED module. Although several techniques, such as micro-Raman spectroscopy, infrared imaging, temperature coefficient of diode-forward voltage and so on, are applied to estimate the junction temperature, there is no method that can simultaneously measure the junction temperature of the several chips located in a LED module, especially in a phosphor-deposited white-LED. Under these situations, we have been developing a pulsed-laser Raman scattering method for estimation of the junction temperature of LED, where the Raman shift of E2H mode of GaN layer is observed. This method has potentials of remoteness and simultaneous multipoint measurement, which lead to 2D mapping of the temperature of the LED module. This technique has been applied successfully to measure the junction temperature of phosphor-less blue-LED, and is considered to be one of the prospective candidates of temperature estimation method of white-LED. In this presentation, simultaneous observation of Raman spectra from several LED chips in a phosphor-less blue-LED module by a pulsed-laser Raman scattering method is demonstrated. Also, the influence of a phosphor deposited on the surface of blue-LED on Raman spectra is discussed..