• 한국산학기술학회논문지
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• 제13권10호
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• pp.4725-4732
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• 2012

본 논문은 다면체 반사판(Multifaceted Reflector :MR16)을 사용하여 할로겐 광원을 LED광원으로 대체함으로서 기존 MR16의 장점을 수용하고 더불어 단점을 커버할 수 있는 MR16에 대해 연구하였다. 본 연구에서는 4매의 비구면 렌즈를 1 Sheet로 한 광학계를 적용한 LED용 MR16을 개발하였다. 광학 소프트웨어를 통해 비구면 광학계를 설계하였고, 조명 시뮬레이션 프로그램을 사용하여 설계 데이터의 조명성능을 예측하였다. 또한 방열 해석 프로그램을 통해 Heatsink의 열 성능을 예측하였다. 최종적으로 시뮬레이션 분석 데이터를 토대로 광학 시제품을 제작하고, 직접 성능을 측정하여 설계데이터와 비교 분석하여 다음과 같은 결과를 얻었다. MR16의 배광각도는 $50^{\circ}{\sim}60^{\circ}$내외로 시뮬레이션 분석 결과와 시제품의 측정결과가 유사하였으며, 온도측정 결과는 1분 30초경부터 열 평행을 이루었고 이의 시뮬레이션 결과와 시제품 모두 최대 $60^{\circ}C$까지 열이 오르는 것을 확인하였다. 마지막으로 MR16의 배광곡선 역시 제작된 시제품의 성능측정 결과가 유사함을 보여주었다.

• 한국기계가공학회지
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• 제14권4호
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• pp.62-72
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• 2015

Interest in three-dimensional (3D) printing processes has grown significantly, and several types have been developed. These 3D printing processes are classified as Selective Laser Sintering (SLS), Stereo-Lithography Apparatus (SLA), and Fused Deposition Modeling (FDM). SLS can be applied to many materials, but because it uses a laser-based material removal process, it is expensive. SLA enables fast and precise manufacturing, but available materials are limited. FDM printing's benefits are its reasonable price and easy accessibility. However, metal printing using FDM can involve technical problems, such as suitable component supply or the thermal expansion of the heating part. Thus, FDM printing primarily uses materials with low melting points, such as acrylonitrile butadiene styrene (ABS) or polylactic acid (PLA) resin. In this study, an FDM process for enabling metal printing is suggested. Particularly, the nozzle and heatsink for this process are focused for stable printing. To design the nozzle and heatsink, multi-physical phenomena, including thermal expansion and heat transfer, had to be considered. Therefore, COMSOL Multiphysics, an FEM analysis program, was used to analyze the maximum temperature, thermal expansion, and principal stress. Finally, its performance was confirmed through an experiment.

• 한국전기전자재료학회논문지
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• 제27권8호
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• pp.541-546
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• 2014

Korea Expressway Corporation established standard of LED lighting fixture in Dec. 2013. To raise compatibility, the standard requires a fixed form and it is applied to street lights and tunnel lights, etc. Because streetlight has different circumstance condition from tunnel light that is down light and exposed to constant wind velocity over height of 8 meters, in case of LED module which has the same shape, characteristic of radiant heat can be different. In this paper, we designed 25 [W] LED Module that is designated by standard of Korea Expressway Corporation and analyzed characteristics of radiant heat about natural convection and forced convection. It is dropped 10.12[$^{\circ}C$] that max temperature is decreased by increasing 20 mm of bended height of heatsink at the condition of natural convection. Radiant heat characteristic of bended height 35 mm became 78.08[$^{\circ}C$] at the condition of natural convection, 55.30[$^{\circ}C$] at the condition of forced convection so that 22.78[$^{\circ}C$] is decreased that is 29.1[%] decrease. Bended height 55mm became 67.96[$^{\circ}C$] at the condition of natural convection, 48.04[$^{\circ}C$] at the condition of forced convection so that 19.92[$^{\circ}C$] is decreased that is 29.3% decrease.

• 한국산학기술학회논문지
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• 제20권5호
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• pp.87-92
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• 2019

본 논문은 집단보호장비에 들어가는 회로카드조립체의 고장 원인 분석 및 품질 개선에 관한 연구이다. 해당 장비는 현재 운용중인 무기체계의 구성품으로 냉난방 기능뿐만 아니라, 화생 방어 역할을 한다. 그런데 군에서 운용중에 응축부조립체의 팬이 동작하지 않는 현상이 다수 발생되었다. 이에 따라 고장 원인을 분석하였고 특정 회로카드조립체가 소손됨을 확인하였다. 고온의 환경조건에서 지속적인 냉방가동에 따라 부품이 가열되고 이에 따라 고온에 노출된 전자부품이 열화되어 소손됨을 알 수 있었다. 따라서 본 논문은 이를 해결하기 위해 방열판을 적용하여 과온 동작에 의한 고장빈도를 낮추고 회로카드조립체의 수명을 연장한 품질 개선에 관한 연구이다. 개선된 회로카드조립체는 실험을 통해 방열성능을 확인하였다. 뿐만 아니라 체계 호환성 검사, 양압유지, 소음 시험, 작동시험 등을 통해 성능검사를 마쳤으며 현재 개선된 제품을 적용중이다. 이번 개선을 통해 현재까지 해당 회로카드조립체에서 발생한 고장은 없으며 해당 장비의 품질이 향상됨을 확인하였다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.493-498
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• 2004

The EMI noise source in a switching mode power supply is dominated by a common mode noise. If we can understand the common mode noise occurring mechanism, it is resulted to find out the method to suppress the EMI noise source in the switching mode power supply. The common mode noise is occurring mostly due to circuit is unbalanced which is caused by the capacitive coupling to frame ground, which passes through a heatsink of the switching devices. This research paper presents a new effective balancing method of buck converter circuit by mean of grounding the parasitic and compensation capacitors in correct proportion which is called that the common mode impedance balance (CMIB). The CMIB can be achieved by source, transmission line and termination balanced, such balancing, the common mode current will be cancelled out in the frame ground. The greatly reduced common mode noise can be confirmed by the experimental results.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.313-317
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• 2003

Porthole die extrusion is the method which put the billet in the container and push it between die hole by ram. This method make it possible that product manufacture which have complex shape of area with excellent induction of area, in addition that this is economical. So this method is used as the basic manufacturing method of many industrial materials. The subject of this research is the forming technology development of heat sink which is being produced by extrusion process in my country. Flow condition of extrusion for heat sink, and metal flow of billet in the die are estimated by the means of rigid-plasticity finite element method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1472-1475
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• 2004

Current processor power consumption has dramatically increased and already reached 115 Watts. Therefore, Heat sink design needs more high accuracy in 1U server. The target performance of heat sink is very dependent of fin geometry and it is also seriously affected by design conditions such as fan type, air duct shape and heatsink design parameters. The present paper investigates the behavior of heat sink performance under various conditions. The present work addresses pressurized type plane fin heat sinks having dimension of 40 mm by 40 mm by 56 mm fan.

• 한국기계가공학회지
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• 제16권2호
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• pp.142-148
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• 2017

The objective of this study is to investigate the cooling characteristics of a heat sink for an LED headlight used in passenger cars. To this end, this study conducts the experimental and numerical analysis of the heat sink heated at constant heat fluxes without air flow applied. In the experiments, heat was transferred at a constant heat flux through the bottom of a heat sink. The measured temperature on pre-selected locations of the heat sink was in good agreement with the numerically predicted one. The experimental and numerical results indicate that the convective heat transfer coefficient for the natural convection mode was decreased by increasing the heat flux applied to the bottom of heat sink, lowering the cooling capabilities.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2014년도 추계학술대회 논문집
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• pp.152-154
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• 2014

본 논문에서는 단상 5kVA의 용량을 갖는 3-레그 방식의 고효율 자동전압조정기에 최적화된 방열설계가 제안된다. 3-레그 자동전압조정기의 경우 스위칭 알고리즘에 따라 스위칭 횟수가 줄어들어 효율이 좋은 장점이 있다. 스위칭 소자로 IGBT를 사용하여 열 분배가 중요함으로 전력변환 장치의 신뢰성과 안전성을 높일 수 있도록 최적화된 방열설계안을 제시하고 설계의 타당성을 위해 시뮬레이션을 통한 검증을 수행하였다.

• 전력전자학회논문지
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• 제18권2호
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• pp.117-122
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• 2013

The distributed power conversion LED driver circuit using parasitic inductance is proposed in this paper. while the conventional LED driver circuit is composed of the large size devices and heatsinks, the proposed circuit can be realized with the small sized no heatsink based. since the processing power can be effectively distributed. Also by using the wire parasitic inductance of the LED string, the proposed circuit can be implemented without external magnetic device. As a result, the proposed circuit which features the small size and volume con be realized even without LED driver module(LDM) board. since, all the device can be attached to the existing LED array Module(LAM) board. Therefore, it features that cost savings and volume reduction of circuit. To confirm the validity of the proposed circuit, theoretical analysis and experimental results from a distributed power conversion LED driver circuit prototype are presented.