• Journal of the Semiconductor & Display Technology
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• v.15 no.4
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• pp.79-85
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• 2016

For long life time and high efficiency, not necessary in improvement of LED chip structure, but also improve heat radiation for decrease heat in LED chip. In this study, efficiency decline factor has been investigated in LED lamp as study heat characteristic, luminance flux and heat resistance. When LED lamp temperature was increased, about 7% loss of luminance flux. In consequence of temperature analysis, width of fin was the most important factor of heat radiation. As a result, secure the enough heat path is very important factor of LED lamp design.

• Journal of Energy Engineering
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• v.28 no.4
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• pp.35-41
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• 2019

In order to overcome these disadvantages, the halogen light source, which was previously used as a vehicle fog light, has increased power consumption and a short lifetime, and thus, an automobile light source is gradually being replaced with an LED. However, when the vehicle LED fog light is turned on, there is a disadvantage in reducing the life of the fog lamp due to the high heat generated from the LED. The heat generated by the LED inside the fog lamp is mainly emitted by the heatsink, but most of the remaining heat is released to the outside through convection. When cooling efficiency decreases due to convection, thermal energy generates heat to lenses, reflectors, and bezels, which are the main parts of lamps, or generates high temperatures in LED, thereby shortening the life of LED fog lights. In this study, we tried to improve the heat dissipation performance by convection in addition to the heat dissipation method by heat sink, and to determine the installation location of vents that can discharge the internal air or intake the external air of LED fog lamp for vehicle. Thermal fluid analysis was performed to ensure that the optimal data were reflected in the design. The average velocity of air increased in the order of Case3 and Case2 compared to Case1, which is the existing prototype, and the increase rate of Case3 was relatively higher than that of other cases. This is because the vents installed above and below the fog lamps induce the convective phenomena generated according to the temperature difference, and the heat is efficiently discharged with the increase of the air speed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.2
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• pp.1-7
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• 2012

LED package with 4[mm]-height mold was manufactured and the surface temperature was measured directly using both thermocouple and thermal infrared (IR) camera. FVM simulation was conducted to estimate the surface temperature of the same LED package under the same condition, by which the accuracy of the simulation was secured. Then, the effects of the height and thermal conductivity of the mold on the junction temperature of the LED package were investigated by FVM simulation. The results showed that the junction temperature decreased by 10[$^{\circ}C$] when the mold height was 3~5[mm], but the thermal conductivity of the mold didn't affect the junction temperature significantly.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.12
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• pp.915-919
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• 2013

This is the study on the development of fusion heat dissipation of carbon magnesium materials. The purpose of this study is for effective utilization of heat emission which is the core of LED lighting. The result of study enabled the derivation of side satisfying result of making the surface temperature of lighting to be below $70^{\circ}C$ (actual measurement: $58^{\circ}C$) using magnesium. The lighting products that use magnesium was made possible based on the result of this study. Also from the performance aspect such as light distribution, the measurement of light efficiency demonstrated the level of 90 lm/W. Therefore the commercialization of lighting was made possible and the efficiency could be further enhanced by supplementation of LED performance.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.119-124
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• 2007

24" LCD Monitor용 LED BLU를 개발하기 위하여 1.5W R,G,G,B가 하나의 PKG에 들어있는 LED를 이용하여 Direct type의 Back Light Unit을 개발하였다. 방열 및 휘도 균일도를 고려하여 LED part를 설계, 개발 하였고 LED를 pulse로 구동하기 위하여 Switching circuit이 포함되는 구동회로 부분을 설계, 개발하였다. 또한 Color Sensor와 ICM (Integrated Color Management) IC를 사용하여 Color를 Control하는 제어회로 부분도 개발을 하였다. 제어회로 부분을 개발하기 위하여 MicroController를 사용하였으며 ICM IC와의 통신을 위한 부분도 개발하였다. 이러한 구성을 개발하여 시제품을 직접 제작하였다. 평가를 위하여 성능시험을 실시하였고 광학적인 평가도 시행하였다. 제작된 시제품은 $L558{\times}W359{\times}H30$으로 하였다. 휘도는 목표휘도를 이루었으며 균일도는 85% 이상이 되었다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.10a
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• pp.99-102
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• 2009

Fixture 일체형 LED 다운라이트(Downlight)의 광 효율 향상을 위하여 LED 장착위치 및 Reflector 길이, 히트싱크(Heat sink) 형태에 따른 광도(luminous intensity)와 기구효율(luminaire efficiency)을 시뮬레이션을 통하여 비교분석 하였다. 또한 히트싱크의 방열 설계를 시뮬레이션 하고 상용 LED 패키지 (Cree, XP-E P4)를 사용하여 시제품을 제작 하여 그 성능을 평가하였다. 그 결과 광속 9661m, 상관 색온도(CCT) 3,060K, 연색지수(CRI) 82의 광 특성을 갖는 LED 다운라이트를 개발하였다.

• Journal of the Korean institute of surface engineering
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• v.51 no.6
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• pp.415-420
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• 2018

The possibility of an improvement in heat dissipation performance of aluminum alloy heat sink for shipboard LED luminaries through plasma electrolytic oxidation (PEO) was investigated. Four different PEO coatings were produced on aluminum alloy 5052 in silicate based alkaline solution by varying current density ($50{\sim}200mA/cm^2$). On voltage-time response curves, three stages were clearly distinguished at all current densities, namely an initial linear increase, slowdown of increase rate, and steady state(constant voltage). It was found that the increase in current density caused the breakdown voltage to increase. Two different surface morphologies - coralline porous structure and pancake structure - were confirmed by SEM examination. The coralline porous structure was predominant in the coatings produced at lower current densities (50 and $100mA/cm^2$) while under high current densities(150 and $200mA/cm^2$) the pancake structure became dominant. The coating thickness was measured and found to be in a range between about $13{\mu}m$ and $44{\mu}m$, showing increasing thickness with increasing current density. As a result, $100mA/cm^2$ was proposed as an effective process parameter to improve the heat dissipation performance of aluminum alloy heat sink, which could lower the LED operating temperature by about 30%.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.12
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• pp.1-8
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• 2012

The performance and lighting characteristics of the LED depend on cooling condition because the power LED generates lots of heat. In this paper, the effect of the generated heat from power LED module on lighting characteristics and performance is measured and evaluated. For experiments, the transient temperature of a power LED module with cooling condition is measured. In addition, the temperature and lighting characteristics of the LED module are measured during the steady state. As a result, the cooling condition is less effective on the lighting characteristics of the LED module at rated current but the cooling condition extremely affects those of the LED module over the rated current. Because high temperature of the power LED module causes the low phosphor conversion, luminance efficiency becomes low and color temperature becomes high. When power LED module are driven over the rated condition, higher temperature is directly related to lighting characteristics and performance of the LED module rather than higher current.

• Korean Journal of Optics and Photonics
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• v.21 no.3
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• pp.118-122
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• 2010

We fabricated a high power LED lamp structure which utilizes the modified COB concept based on an MCPCB with insulation layer partially removed. In the proposed structure, no insulation layer exists between the LED chip and the metal base. As a result, the heat generated in the chip is easily dissipated through the metal base. In actual measurement as well as in thermal simulation, the fabricated LED lamp structure showed superb thermal properties, compared to the SMD LED lamp attached on an MCPCB or the LED lamp based on conventional COB concept.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.4
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• pp.79-84
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• 2010

In recent years, conventional streetlight is replaced by LED streetlight to reduce power consumption dramatically and to maximize lighting effects. However the characteristic of power LED itself driven by high current to increase the illumination, we need to develop effective heat release device. This study suggests new concept of heat dissipation device using PCM (Phase Change Material) and shows an experiment results to investigate thermal effects of PCM.