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금속의 평면 접촉면에서 표면부식에 의한 열접촉 저항의 변화
김철주,김원근,Kim, C.J.,Kim, W.G. 대한설비공학회 1991 설비공학 논문집 Vol.3 No.4
The corrosion effects on thermal contact resistance were experimentally studied for a given contact interface of a couple of metals. 2 cylindrically shaped test pieces, the one was carbon steel whose surface was machined by lathe and the other was stainless steel, ground, were come into contact under pressure, and then submerged to $HNO_3$ gas environment. While the corrosion process was going on, the thermal contact resistance was measured with time. The experiment was performed for 2 cases; 1) Highly compress the test pieces and then bring them to $HNO_3$ gas environment. 2) Anteriorly corrode the interface under low contact pressure and then increase the contact pressure. The results were as follows; In 1st. case of experiment, the thermal contact resistance seemed to be very stable, and showed low values with a tendancy of small decrease with time. But in 2nd. case the resistance was unstable and jumped to a value of 200-250% more then that expected for uncontaminated interface. More over it demonstrated some increase with time.
BLDC 모터에서 전류시간에 의한 토크맥동에 관한 연구
김철주(C.J.Kim),강병희(B.H.Kang),목형수(H.S.Mok),김덕근(D.K.Kim),김병규(B.K.Kim) 전력전자학회 2000 전력전자학술대회 논문집 Vol.2000 No.11
Torque pulsation generated in every commutation period is the main drawback of BLOC motor, which deteriorates the precision of BLOC motor. Many methods to solve this problem have been proposed. In this paper, a new torque model considered with decaying phase back EMF is introduced and from it the cause of torque pulsation in commutation period is analyzed. From this analysis, new algorithms to reduce the torque pulsation by commutation time are proposed and with simulation, the validity is verified.
중심부에 열파이프를 갖는 2중 진공관형 태양열 집열기의 열전달특성에 대한 기초연구
김철주(C. J. Kim),이진성(J. S. Lee) 한국태양에너지학회 1996 한국태양에너지학회 논문집 Vol.16 No.1
본 논문은 Dewar-Type 진공관형 태양열 집열기에 열회수원으로 열파이프를 사용하였을때 집열면과 열파이프의 열전달특성에 관한 연구이다. 유리관 중심에 열파이프를 설치하여 내부 집열 유리면에 흡수된 태양복사에너지가 공기층의 전도, 복사에 의해 열파이프로 전달된다. 실제 태양 복사하에서 반사판에 의한 집열면의 온도분포와 열파이프의 작동특성을 다양한 일사량, 입사각조건에 대하여 알아보았으며 다음과 같은 결론을 얻을 수 있었다.<br/> (1) 초기시동후 정상작동에 도달되는데 약 15분 정도가 소요되며, 불규칙한 일사량변화에 대해서도 안정된 작동을 나타내었다.<br/> (2) 집열면의 온도분포는 상부가 하부보다 약 5~6℃ 정도 크게 나타나는데 이는 반사면에서 재반사되어 입사되는 복사강도가 직접 전달되는 복사보다 감쇠되어 있음을 나타낸다.<br/> (3) 내부 집열면과 열파이프사이의 열전달은 공기층의 전도와 복사에 의해 지배되며, 그 효과의 비는 약 2:1을 나타낸다.<br/> (4) 입사각도가 0˚, 30˚, 60˚ 일때의 집열효율이 약 30~50%까지 나타나며, 입사각이 커질수록 반사판에서 재반사된 태양광선의 유실성분이 줄어 효율이 다소 증가한다. This study investigated heat transfer characteristics between absorber and heat pipe used to extract heat from Dewar-type evacuated tubular collectors. Absorbed solar radiation energy in inner absorber tube transfered to heat pipe which is located at the center by conduction and radiation. Absorber temperature distribution affected by reflector and operational characteristics of heat pipe were carried out by experimental method under actual various irradiance and incident angle conditions. The following results were obtained.<br/> (1) The heat pipe was required about 15min. to obtain steady state operation after start up and operates stable during various irradiance conditions.<br/> (2) Upper part of absorber temperature distribution is higher about 5~6℃ than lower part of it, because reflected radiation energy from reflector is diminished than direct incident radiation energy.<br/> (3) Heat transfer between absorber and heat pipe is predominent conduction and radiation. The ratio of these effect was showed about 2:1.<br/> (4) The collector efficiency was about 30~50% when incident angles are 0°, 30°, 60°, The collector efficiency was increased to some extent as increasing incident angles, because reflected radiation energy from reflector is diminished.
주병권,고창기,김철주,차균현,오명환 ( B . K . Ju,C . G . Ko,C . J . Kim,K . H . Tchah,M . H . Oh ) 한국센서학회 1994 센서학회지 Vol.3 No.1
In this study, we fabricated and characterized a calorimetric-type flow sensing element using a micromachined silicon substrate. The cooling and heating effects resulted from the gas flow were measured by two temperature sensors located at both sides of the heating resistor, and the insulator diaphragm was employed as a substrate in order to improve thermal isolation. The sensor generated 0∼378.4mV output signal under 10V bridge-applied voltage when the nitrogen gas was passed on the sensor surface having a mass flow rate of 0∼0.25grs/min, and reached to the stable operating condition within 10 seconds.
김성대(S. D. Kim),성병호(B. H. Sung),강환국(H. K. Kang),김철주(C. J. Kim) 한국에너지학회 2003 한국에너지공학회 학술발표회 Vol.2003 No.-
For the present study, three heat pipes with different thickness of sintered metal wick were manufactured, and their operational performances, such as capillary limit and thermal resistance were tested and compared with theoretical predictions. Experimental results showed good agreement with those by the theoretical model, and that seemed to present that the sintering process we had developed in the present study was valid.