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In-line 맥동관 극저온 냉동기의 성능특성에 관한 실험적 연구
박성제(Seong-Je Park),홍용주(Yong-Ju Hong),고준석(Jun-Seok Ko),김효봉(Hyo-Bong Kim),염한길(Han-Kil Yeom),인세환(Se-Hwan In) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
Stirling type pulse tube cryocoolers are very attractive for cooling of diverse applications because it has several inherent advantages such as no moving part in the cold end, low manufacturing cost and long operation life. In recent years, the pulse tube cryocooler have cooling capacities and thermal efficiencies comparable with the Stirling cryocooler. These advantages promote the widespread use of the pulse tube cryocooler in many fields, specially in space-borne application that require a long life and stable temperature. Pulse tube cryocooler for cooling infrared and cryo-sensors is currently under development at KIMM. Our coolers are specifically designed to work in the thermal imaging device and to meet requirements such as cooling capacity, COP and high reliability. This paper presents the results of a series of performance tests for the in-line type pulse tube cryocooler. Experimental investigations have been conducted to evaluate their performance characteristics with respect to several parameters such as the phase shifter, operating pressure and operating frequency of the linear compressor.
적외선 센서 냉각용 맥동관 극저온 냉동기의 성능특성에 관한 실험적 연구
박성제(Seong-Je Park),홍용주(Yong-Ju Hong),고준석(Jun-Seok Ko),김효봉(Hyo-Bong Kim),염한길(Han-Kil Yeom),인세환(Se-Hwan In) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.11
A pulse tube refrigerator is a small scale cryocooler which was invented by Gifford and Longsworth in 1963. It has the advantages of high reliability and low vibration because it has no moving part in the cold part. In recent years, the pulse tube cryocooler have cooling capacities and thermal efficiencies comparable with the Stirling cryocooler. These advantages promote the widespread use of the pulse tube cryocooler in many fields, specially in space-borne application that require a long life and stable temperature. An in-line pulse tube cryocooler has been designed and tested in our laboratory. The main part of the cryocooler, consisting of an in-line assembly of aftercooler, regenerator, cold heat exchanger, inertance tube, buffer and hot heat exchanger. Generally, a long tube with small diameter is used as an inertance tube and it imposes resistance and impedance to gas flow simultaneously. Phase between pressure and flow at cold-end is adjusted by length of the inertance tube with fixed diameter. This paper presents the results of a series of performance tests for the in-line type pulse tube cryocooler. Experimental investigations have been conducted to evaluate their performance characteristics with respect to several parameters such as the phase shifter, operating pressure and operating frequency of the linear compressor.
부동산신탁유형 및 신탁회사의 재무비율과 영업용순자본비율(NCR)과의 상관관계 분석
인세환(In Se hwan),서충원(Suh Chung Won) 한국부동산학회 2018 不動産學報 Vol.73 No.-
부동산신탁회사들은 지난 몇 년간 주택시장의 호황에 힘입어 사상 최대의 실적을 기록해 왔다. 그러나 최근 정부의 부동산시장 및 투자수요의 규제 정책으로 인해 향후 부동산 경기가 둔화될 가능성이 있으며, 이러한 경기 변동성으로 인해 그동안 토지신탁 등 과도한 차입 레버리지를 활용하여 수익을 극대화해 온 부동산신탁회사들은 위험에 그대로 노출되어 실적이 감소하거나 위험이 증가할 우려가 있다. 이에 부동산신탁회사의 재무건전성 비율인 NCR을 기준으로 하여 부동산신탁 유형과 NCR간의 상관관계 분석을 통해 재무건전성에 영향을 미치는 부동산신탁유형과 위험요인을 분석해보고자 한다. 이와 더불어 부동산신탁회사의 ROA, ROE, 자기자본비율, 부채비율 등 주요 재무비율과 NCR과의 상관관계 분석을 통해 부동산신탁회사의 재무건전성에 영향을 미치는 위험요인을 분석해보고자 한다.
박성제(Seong-Je Park),홍용주(Yong-Ju Hong),고준석(Jun-Seok Ko),김효봉(Hyo-Bong Kim),염한길(Han-Kil Yeom),인세환(Se-Hwan In) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.11
This paper presents the results of a series of performance tests for the Stirling cryocooler. Stirling cryocooler is relatively compact, reliable, commercially available, and uses helium as a working fluid. Infrared sensor systems incorporating cryocoolers are required to be qualified to the appropriate environmental specification. Crank driven Stirling cryocooler have matured to the stage of undergoing formal qualification test program. The thermal environment and vibration tests of the Stirling cryocooler are presented in this paper. We performed that low and high temperature keeping test from -40℃ to +70℃ and operating test at high and low temperature cyclic range with acceptance tests performed at scheduled intervals. Cooling capacity was determined as a function of cooler components temperatures at the compressor, hot end and cold tip. Tests performed on this cooler have been successful with a measured cooling performance of more than 0.4 W@80 K for 20℃ ambient temperature with 40 Wac input power. And, Vibration outputs are measured to 20 kHz for compressor and expander, respectively.