• Aerospace Engineering and Technology
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• v.10 no.2
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• pp.20-28
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• 2011

The electro-optical payload of a low-earth orbit satellite is thermally decoupled with the bus, which supports a payload for a mission operation. The payload has a cooling unit of FPA(Focal Plane Assembly) which has a thermal behavior increasing its temperature instantly during an operation in order to dissipate a waste heat into the space. The FPA cooling unit should include a radiator and heatpipes with a sufficient performance in worst hot condition, and a heater design to maintain its temperature above a minimum allowable temperature in the worst cold condition. In this paper, we analyzed the thermal requirements and the heater design constraints from the thermal analysis results for the current thermal design of the FPA cooling unit and the design elements of the better heater design were found.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.8
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• pp.767-774
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• 2010

In a passive-type PEMFC stack, axial fans operate to supply both oxidant and coolant to cathode side of the stack. It is possible to make a simple system because the passive-type PEMFC stack does not require additional cooling equipment. However, the performance of a cooling system in which water is used as a coolant is better than that of the air-cooling system. To ensure system reliability, it is essential to make cooling system effective by adopting an optimal stack design. In this study, a numerical investigation has been carried out to identify an optimum cooling strategy. Various channel configurations were applied to the test section. The passive-type PEMFC was tested by varying airflow rate distribution at the cathode side and external heat transfer coefficient of the stack. The best cooling performance was achieved when a channel with thick ribs was used, and the overheating at the center of the stack was reduced when a case in which airflow was concentrated at the middle of the stack was used.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.209-212
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• 1999

여름철 재배시설의 기본적인 온도상승 억제방법은 차광과 환기이지만 이 방법만으로는 작물의 적정 생육온도에 접근하기 어렵기 때문에 추가적인 냉방 장치가 도입되고 있다. 현재 온실의 냉방시스템은 물의 증발잠열을 이용한 Pad and Fan 방식과 Fog 방식의 냉방시스템이 보급되어 있으나, 국내의 지역기상조건을 감안한 연구가 충분히 이루어지지 못하여 냉방시스템의 설치와 운영에 대한 기준이 명확하지 못한 실정이다. 따라서, 본 연구에서는 현장 실험을 통하여 기초적인 자료를 수집하였다.

• Proceedings of the Korean Society for Bio-Environment Control Conference
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• 1999.11a
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• pp.241-244
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• 1999

시설원예는 노지원예와 달리 인위적인 환경조절을 통하여 주년안정생산이 가능하여야 하고 단위면적당 생산성을 증대시키면서 품질향상을 극대화시키는 것이 생산의 목표이다. 따라서, 주년안정생산을 위하여 고온기에 작물생산이 가능하도록 시설내 고온환경을 조절해야할 것이다. 고온환경을 조절하기 위한 냉방방식에는 자연환기 및 팬을 이용한 온실내부의 공기를 치환하는 방법, 온실내ㆍ외부에 차광망을 설치하여 온실내로 유입되는 일사량의 일부를 차단하는 방법, 수분증발을 통하여 온실내부의 잠열을 빼앗는 증발냉각방식, 히트펌프나 에어컨을 이용한 기계적인 방법이 이용되고 있다. (중략)

• The Korean Publising Journal, Monthly
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• s.144
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• pp.14-16
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• 1994

인간은 문명의 지층 속에서 태어난 벌레이며, 책은 문명의 난로이자 화덕이다. 그런 의미에서 책의 발견은 제2의 창조이다. 신은 사물을 날것으로 만들었지만, 인간은 책을 통하여 세계를 뜨뜻하게 익혀진 것으로 만들었다. 너무 뜨거워진 결과가 환경오염이다. 그 잉여온도를 냉각시키는 활동 역시 책을 통해 이루어진다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.05a
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• pp.405-406
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• 2010

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2002.10a
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• pp.19-20
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• 2002

• Proceedings of the SAREK Conference
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• 2003.07a
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• pp.161-161
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• 2003

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.203-206
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• 2002

We implemented 2.5Gbps optical transponder by using uncooled laser diode and measured temperature effects of 2.5Gbps uncooled laser diode, such as optial power vs. injection current, extinction ratio, and power penaty.

• Journal of IKEEE
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• v.24 no.2
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• pp.673-676
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• 2020

In this paper, we propose a whole-body management system using ultra-low temperature cyclical cooling method combined with IT technology. The proposed system has the following characteristics. First, it minimizes maintenance costs by circulating nitrogen gas cooled by ultra-low temperature inside the controller. Secondly, based on the information measured by the temperature sensor and oxygen concentration sensor, nitrogen gas is supplied to provide safe ultra-low temperature whole-body management. Thirdly, after entering the user's height, it provides convenient, ultra-low temperature whole-body care that can be controlled using an automatic lift. Fourth, it provides an easy-to-access, easy-to-manage GUI and a manager-only web program for whole-body management system operation. The results tested by the authorized testing agency to assess the performance of the proposed system were measured in the range of ±5%, the world's highest temperature sensor accuracy, and a range of -110℃ to -150℃ greater than the world's highest whole-body management temperature range(-110℃ ~ -140℃). In addition, humidity was measured at less than 40%, the world's highest, and oxygen concentration was more than 18%, the world's highest. Therefore, the effectiveness of the methods proposed in this paper was demonstrated because they produced the same results as the world's highest levels.