http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
냉각수유로가 포함된 열적조건이 PEMFC 성능에 미치는 영향
김미로(Mi-Ro Kim),안병재(Byung-Jae Ahn),최영민(Young-Min Choi) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_1
There are several types of fuel cells available to transform chemical energy directly to electrical energy. One of these, the proton exchange membrane fuel cell, operates at a lower temperature than other types of fuel cells and it may be a useful power source for future automobiles and stationary power plant. For the development of high performance fuel cell, water and heat management of the PEMFC is important. To investigate the influence of coolant passage, three types of coolant passage models are studied numerically. The model results notify that optimal shape of cooling passage strongly depends on shape of gas channel of its geometrical type. The effects of operating conditions like humidity, including temperature effect are also studied. The extremely high inlet humidity may cause cathode flooding issues and increases the load of auxiliary devices, such as humidifier systems. On the contrary, the excessively low humidity may lead to membrane dehydrating problem. From a thermal point of view, the extremely high cell temperature may cause critical performance problem. So optimized coolant passage design is important.
김미로(Mi-Ro Kim),안병재(Byung-Jae Ahn),최영민(Young-Min Choi) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.5_1
A three-dimensional computational fluid dynamics(3-D CFD) model of the proton exchange membrane fuel cell(PEMFC) is presented to explain the characteristic of its behavior. Many researchers have numerically studied small(~10-50㎠) PEMFC systems. But 3-D numerical model of a commercial-sized PEMFC with reacting area on the order of 200~ ㎠ is still hard to perform effectively. This study applies 3-D CFD model to a commercial-sized(250㎠) PEMFC selected from research models to show its usefulness. Various types of bi-polar plate channel including standard serpentine shaped gas flow channel are proposed and examined. The effects of operating conditions like humidity, including temperature effect, and gas flow rates are also studied. Cathode flooding or membrane dehydrating conditions could be expected through numerical analysis.
자동차용 열교환기에 대한 준 미시적 수치 해석 기법의 개발
박종택(Jong-Tack Park),허남건(Nahmkeon Hur),최봉근(Bong Keun Choi),안병재(Byung Jae Ahn) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
This study investigates the development and verification of the semi-microscopic numerical analysis method which satisfies either efficiency and accuracy when analyzing automotive heat exchanger. the coolant passage and the wall of the passage have been simulated to complement the weak points of the macroscopic numerical analysis, and the analysis has been conducted replacing the louver fin and air inside the heat exchanger by porous medium. This has forecasted the performance of the real automotive heat exchanger developing and applying a user subroutine for commercial code(STAR-CD) for applying heat exchange model to the air and the louver fin. The results of this study has verified the adequacy with the macroscopic numerical analysis method and the experimental results about previous automotive heat exchanger by Jurng et al. The improvement can be expected in the fast and accurate analysis of Under-hood thermal management developing the semi-microscopic numerical analysis. As a result, the reduction of the time for designing and developing automobiles can be resulted in.
정상 관상동맥조영술시 cardiac troponin 1 상승의 원인
배우형 ( Woo Hyung Bae ),전국진 ( Kook Jin Chun ),오준혁 ( Jun Hyok Oh ),이동원 ( Dong Won Lee ),안병재 ( Byung Jae Ahn ),김성호 ( Seong Ho Kim ),이준상 ( Joon Sang Lee ),김무영 ( Moo Young Kim ),이현국 ( Hyeon Gook Lee ),고우석 ( 대한내과학회 2005 대한내과학회지 Vol.69 No.5
목적 : Cardiac troponin I (cTnI)는 심근 조직에 절대적으로 높은 예민도와 특이도를 보인다. 그러나 심근 손상을 의미하는 cTnI 증가가 항상 관상동맥질환으로 인한 심근경색이나 허혈을 의미한다고 볼 수는 없다. 이에 저자들은 cTnI가 증가되어 있으면서, 관상동맥조영술에서 정상이거나 미소병변을 보이는 경우 그 유발 원인을 알아보고자 하였다. 방법 : 2002년 3월부터 2004년 2월까지 부산대학교병원을 내원한, cTnI가 상승하였으나 관상동맥조영술에서 정상소견 또는 복잡 병변이나 혈전이 관찰되지 않고 50% 미만의 협착소견인 미소병변을 보이는 33명의 환자들을 대상으로 후향적 추적조사를 시행하였다. 결과 : 유발 원인으로는 중증 심부전이 7명, 변이형 협심증이 7명, 심근염이 5명이었다. 빈맥이 유발 원인인 경우가 4명이었는데, 각각 동성 빈맥, 상심실성 빈맥, 발작성 심방세동 그리고 지속성 심실빈맥이었으며, 이들 중 2명에서 혈역학적 장애를 보였다. 그 외에 심외막염이 1명, 중증 심근교가 1명, 횡문근융해증이 1명 그리고 뇌경색이 1명이었다. 대상 환자들을 42±34주 동안 추적관찰 하였는데, 급성 심근경색증이 발생한 경우는 없었다. 결론 : cTnI가 심근손상의 매우 예민하고 특이적인 지표이지만, cTnI 상승은 심근경색이나 허혈 이외의 다른 원인에 의해 일어날 수 있고, 관상동맥조영술에서 특이소견 없이 발생할 수 있으므로 이에 대한 고려가 필요하리라 사료된다. Background : Cardiac troponin I (cTnI) is most recently described and has nearly absolute myocardial tissue specificity, as well as high sensitivity. But an increased value for cTnI that indicates myocardial injury is not always synonym of myocardial infarction or ischemia due to coronary artery disease. Methods : Retrospective follow-up study for whom underwent coronary angiography for suspected coronary artery disease was done if they had an elevated cTnI value and angiographically normal or minimal disease. Results : 33 patients were qualified. Cut-off value for elevated cTnI was 0.06ng/mL. Increased cTnI values were attributed to severe congestive heart failure in 7 patients, variant angina in 7 patients, myocarditis in 5 patients, pericarditis in 1 patient, severe myocardial bridge in 1 patient, rhabdomyolysis in 1 patient and cerebral infarction in 1 patient. Tachycardia was precipitating cause in 4 patients (sinus tachycardia, paroxysmal supraventricular tachycardia, paroxysmal atrial fibrillation and sustained ventricular tachycardia for each), two of whom had hemodynamic compromise. 2 of 33 patients had no identifiable cause for a rise in cTnI value. There was no acute myocardial infarction at 42±34 weeks follow-up. Conclusions : Although cTnI is a sensitive and specific marker of myocardial injury, an elevation of cTnI value may have a cause other than myocardial infarction or ischemia and may occur without significant angiographic coronary artery disease.(Korean J Med 69:487-492, 2005)