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조태식(Tae Sik Cho),유성열(Sung Ryul Ryoo),김철주(Chul Ju Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.5
본 연구는 현재 국내에서 개발 중인 분산 형 고속철도 차량의 추진 제어장치를 구성하는 전력변환 반도체의 냉각에 초점을 두고 있다. 이 전력 변환 반도체의 열 부하는 약 40㎾ 정도로 추정되고 있으며, 사용 허용 온도인 100℃ 이하로 유지시키는 것이 본 연구의 목적이다. 이 연구의 실험을 위해 복합 단일 굴곡 휜-판형 열 교환기를 설계 및 제작하여 그 모델에 대한 성능을 평가하고 검증하였다. 그 결과 열 전달 계수가 2500~3000W/㎡K 정도면 10㎾의 열 부하를 충분히 냉각시킬 수 있다는 결론을 얻을 수 있었으며, 이 열교환기의 구조와 유량 등을 고려한 최적 설계를 통해 더 높은 효율의 냉각 장치를 개발한다면 다양한 산업분야에서의 응용을 기대할 수 있을 것이다. This research is a focus to cooling of an electric power conversion semiconductor that is composed of high-speed railway control device. Approximately, the semiconductor's heat flux is 10㎾ and the aim of study is maintaining the using permission temperature which is 100℃. For the study's experiments, It is designed and manufactured the double-wave fin in the heat exchanger, then performing the device. Consequently, if heat transfer coefficients are 2500~3000W/㎡K, the heat source are 10㎾ that can be cooled down enough. Through the optimum design for structure and flow rate of this heat exchanger, it is expected that can develop the higher efficiency cooling device. Also, it can solve such the various industrial as electronics, shipbuilding as well as high speed train.
총담관 각도가 총담관결석 재발에 미치는 임상적 영향: 메타분석 및 고찰
유성열 ( Seongyul Ryu ),조익현 ( Ik Hyun Jo ),김선후 ( Seonhoo Kim ),김연지 ( Yeon-ji Kim ),정우철 ( Woo Chul Chung ) 대한소화기학회 2020 대한소화기학회지 Vol.76 No.4
Background/Aims: Local and systemic factors, such as diabetes, obesity, and hyperlipidemia, are considered risk factors for the recurrence of choledocholithiasis after successful endoscopic clearance. Local factors include the presence of bile sludge, common bile duct (CBD) diameter, and CBD angulation. Among them, it is unclear if acute CBD angulation is preferable to the recurrence of a CBD stone. Methods: PubMed, EMBASE, CINAHL, the Cochrane Library databases, and google website were searched for randomized controlled trials reported in English and undertaken until August 2019. Meta-analysis was performed on all randomized controlled trials for the recurrence of CBD stones between the patients with acute CBD angulation. Results: Eight randomized trials (1,776 patients) were identified, and the total recurrent rate of CBD stones was 18.8% (334/1,776). A CBD angle ≤145° was significantly associated with an increased risk of recurrent CBD stone (OR=2.65, p<0.01). In two prospective studies, acute CBD angulation was not proven to be associated with a recurrence (p=0.39). Conclusions: Approximately 20% of patients with a CBD stone showed recurrence after the complete clearance of the CBD stone, and a CBD angle ≤145° could increase the risk of recurrence. Overall, a large-scale prospective study should be necessary. (Korean J Gastroenterol 2020;76:199-205)
소형 루프 히트파이프에 대한 작동특성 해석과 성능실험 연구
유성열(Seong-Ryoul Ryoo),성병호(Byung-Ho Sung),김철주(Chul-Ju Kim),강환국(Hawn-Kook Kang) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.5
A miniature Loop heat Pipe(LHP) has a great potential in cooling high power computer chips over a long distance. The present study was focused on modelling divers operational characteristics as a capillary limitation, heat transfer paths at the evaporator and those results were used to analyse the performance test data. The experimental model of LHP was designed to have a maximum capacity of heat transport of about 50W when operated under room air cooling condition. The evaporator was of a flat cylindrical shape(30D×14.5H㎜). Ethanol was used as a working fluid. Temperatures at the liquid and vapor lines, evaporator and condenser walls were measured.