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고출력 LED 램프 용 방사형 히트싱크의 형상 및 표면코팅이 LED 냉각성능에 미치는 영향에 대한 연구
김효성(H.S. Kim),박상희(S.H. Park),김동주(D. Kim),김경진(K. Kim) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.1
The purpose of this study is to investigate the cooling performance of radial heat sink used for high power LED lightings by natural convection cooling with surrounding air. Experimental and numerical analyses are carried out together. Parametric studies are performed to compare the effects of geometric parameters in radial heat sink such as the number of fins, fin height, fin length, and thickness of fin base as well as the surface coatings of radial heat sink. In this study, the cooling of 60 W LED lamp is examined with radiative heat transfer considered as well as natural convection. Numerical results show the optimum condition when the number of fin is 40, heat sink height is 120 ㎜, fin length is 15 ㎜, and fin base thickness is 3 ㎜. The difference in temperature of the LED metal PCB is within 1℃ between numerical analyses and experimental results. Also, the CNT coating on the heat sink surface is found to increase the cooling performance significantly.
PQR 순시전력이론에 의한 Dynamic Voltage Restorer의 제어기 설계Ⅰ-기준전압 파형의 발생
김효성(H.S.Kim),이상준(S.J.Lee),설승기(S.K.Sul) 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.7(1)
Dynamic Voltage Restorers (DVR)s are known as the best effective and economic means to compensate for voltage sags and swells [1]-[11] This paper proposes a novel method to generate reference voltages synchronized with the grid whether the line voltages are distorted by a fault or not The proposed reference wave generator (RWG) looks for the original wave forms from the corrupted line voltages and synthesizes the expected positive sequence reference waves for DVRs There is no transient problem on the generated reference waves when the line voltages are distorted by the fault
PQR 순시전력이론에 의한 Dynamic Voltage Restorer의 제어기 설계 Ⅱ-보상전압의 결정
김효성(H.S.Kim),이상준(S.J.Lee),설승기(S.K.Sul) 전력전자학회 2003 전력전자학술대회 논문집 Vol.2003 No.7(1)
This paper discusses how to generate the reference compensation voltages In Dynamic Voltage Restorers (DVR) by use of PQR power theory Sensed three-phase terminal voltages are transformed to PQR coordinates without time delay since the reference voltages In PQR coordinates are de values, the voltage controller for DVRs is simple and easy to design<br/> Proposed control method can be implemented by feedforward controllers or by feedback controllers This paper verified the theory In the feedforward controller of a DVR by experiments