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마이크로 채널을 이용한 LED 냉각 방법에 관한 전산 해석적 연구
김진우(Jin Woo Kim),김재춘,민재홍(Jae Hong Min),정진택(Jin Taek Chung) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
The object of this paper is to propose a method to lower the junction temperature of LED using micro-channel by numerical method. To use LED for lighting, the chip needs to have a large capacity, resulting in concentrate heat in P-N connection area. To solve this problem, micro-channels were merged in PCB. Additionally, the characteristics of heat transfer in substrate including micro-channel were analyzed by CFD according to Re number, aspect ratio of micro-channel, and dimension of substrate. As a result, the parameters which were considered were important factor which influenced the characteristics of LED place on PCB. The junction temperature of LED chip could be lowered under the working temperature.
다양한 형상을 갖는 마이크로 히터의 열특성에 관한 실험 및 전산해석적 연구
김진우(Jin Woo Kim),김재춘(Jae Choon Kim),이준엽(Jun Yub Lee),정진택(Jin Taek Chung) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
As a field of MEMS, micro-heater fabricated by Au is being introduced and developed in recent years. Previous studies about thermal properties of various forms of micro-heater were not sufficient. In this work, numerical and experimental analysis of the heat generation and the temperature distribution of micro-heater packages for 8 different geometric cases were studied. We fabricated a micro-heater package with silicon wafer, on which Cr/Au layer was laminated before 8 geometric forms of micro-heater were patterned. In each cases, temperature distribution was measured with IR thermal camera. According to the experimental results, which show a good agreement with the results analyzed by CFD, it was found that at 0.5W, the temperature of micro-heater chip which contained 20000㎛-long, serpentine shaped micro-heater was elevated to a relatively high temperature of 78℃. Consequently, we proposed a geometry of micro-heater which has effective thermal characteristics.
대체냉매 공기조화기용 로터리 압축기의 성능향상을 위한 최적 토출계에 관한 실험적 연구
윤영,정진택,민만기,Youn, Young,Chung, Jin-Taek,Min, Man-Ki 대한설비공학회 2001 설비공학 논문집 Vol.13 No.2
R410a which is one of HFC refrigerants is being considered to be a promising replacement for R22 widely used in domestic air conditioners. The rolling piston type rotary compressors for R410a have lower energy efficiency than those for R22 because of the high pressure difference between a suction chamber and a discharge chamber in the compression mechanism. in addition, the re-expansion gas loss of the rotary compressor for R410a which occurs a ta clearance volume in a discharge port becomes larger than that for R22 due to high density of R410a refrigerant. Therefore, Pressure-Volume analyses for various design parameters of a discharge system were carried out to improve efficiency of a R410a rotary compressor. The results such as performance dta, over-compression loss, and re-expansion loss were acquired by P-V analyses and analyzed quantitatively. As a conclusion, the optimal specifications of several design parameters of a discharge system were obtained by analyzing P-V diagrams.
티타늄 평활관 및 전열촉진관에서 R-l34a의 관외측 풀비등 열전달 특성에 대한 연구
허재혁,윤린,정진택,문영준,김용찬,Heo Jae-Hyeok,Yun Rin,Chung Jin-Taek,Moon Young-lune,Kim Yongchan 대한기계학회 2005 大韓機械學會論文集B Vol.29 No.7
Pool boiling heat transfer characteristics of R-134a were investigated in titanium plain and low finned tubes. The diameter of test tube was 15.88 mm and the fin density was 33 fpi. Tests were conducted at saturation temperatures of $20^{\circ}C$ and $30^{\circ}C$. Heat fluxes varied from 5000 W/$m^2$ to 50,000 W/$m^2$ based on surface area of the plain tube. The pool boiling heat transfer coefficients of the titanium horizontal plain tube are lower than those of the copper plain tube by $8.2\%$. The boiling heat transfer coefficients of the low finned tube are averagely higher than those of the plain tubes by $34\%$. The average deviation of the Slipcevic correlation from the present data for the low finned tube is $20\%$.
날개의 모서리 형상이 플래핑 운동의 공기역학적 특성에 미치는 영향
오현택(Hyun-Taek Oh),최항철(Hang-Cheol Choi),김광호(Kwang-Ho Kim),정진택(Jin Taek Chung) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.6
Birds and insects have wings of rounded edge profiles. In the experiment, the wing of the square edge profiles had been employed. In this study, two wings which have different shapes of edge are used to investigate the aerodynamic characteristics. One wing has rounded edge profiles and the other has square edge profiles. Two half elliptic shaped wings were designed and scaled up according to the planform of a black-chinned hummingbird, Archilochus alexandri. While the wings were operated in the water, the aerodynamic forces were measured and the flow structures around the wings were visualized using the DPIV. The lift for the wing of rounded edge profiles was higher than that for the wing of square edge profiles. But drag for the wing of rounded edge profiles was lower than that for the wing of square edge profiles. Also the lift to drag ratio for the wing of rounded edge profiles at angle of attack from 0° to 40° was higher than that for the wing of square edge profiles.