• Electronics and Telecommunications Trends
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• v.14 no.5 s.59
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• pp.111-114
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• 1999

전화국사 내 교환기의 신설이나 증설 시에 최적의 열부하 산정이 필요하다. 이를 위해 전화국사의 특성에 알맞은 열부하 계산 프로그램을 윈도우용으로 개발하여 비전문가들도 쉽게 사용할 수 있도록 하고자 한다. 프로그램 구성은 기본자료입력부, 전화국사의 자료입력부, 입력된 데이터를 이용하여 국사의 냉방부하와 냉방시스템의 용량을 계산하는 부분 그리고 출력부분으로 크게 4부분으로 나눌 수 있다. 본 프로그램을 이용하여 한국통신 중앙전화국 5ESS실의 냉방기기용량을 산정해 본 결과, 기존 냉방기기 69USRT의 49%에 해당되는 33.5USRT로 나타나 기존 냉방기기의 용량이 너무 과다하게 선정되었음이 판명되었다. 본 프로그램은 전화국사의 에너지 절약에 기여할 수 있을 것으로 판단된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.12
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• pp.5457-5463
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• 2011

The objective of this study is to investigate cooling performance characteristics of mobile air conditioning system using R744 as an alternative of R-134a. In order to analyze the cooling performance characteristics of the air conditioning system using R744 for a passenger vehicle, the developed air conditioning system using R744 was applied in a real passenger vehicle and tested under various operating conditions with the variation of gas-cooler inlet air conditions, evaporator inlet air temperatures and compressor speeds. As a result, cooling capacity and coefficient of performance (COP) of the tested air conditioning system decreased with the rise of the inlet air temperature of the gas cooler but increased with the rise of the inlet air temperature of the evaporator. In addition, cooling capacity and coefficient of performance (COP) increased by 42.2 % with the rise of the compressor speed from 900 rev/min to 1800 rev/min, but it decreased by 55.4%.

• Journal of Energy Engineering
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• v.2 no.1
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• pp.95-103
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• 1993

A conceptual thermoelectric heat pump(cooling mode) of small capacity is designed. Its performance is investigated through parametric analysis. COP and cooling capacity decease as the ambient temperature increases with ${\mu}$, J, T$\sub$wi/, fixed. To design a system of fixed capacity comes to calculate ${\mu}$ and J when T$\sub$wi/, and T$\sub$a/ are given. As v is fixed by semi-conductor manufacturers, optimum combination of n and I should be searched for ν. Optimum current could be calculated using ${\mu}$-J curve and optimum value of ${\mu}$. COR$\sub$R/ increases as water flow rate increases and T$\sub$a/ decreases. The effect of heat transfer coefficient at hot(heat releasing) side is more significant than that at cold(heat absorbing) side.

• Journal of Bio-Environment Control
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• v.24 no.3
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• pp.147-152
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• 2015

In order to develop the cooling load estimation method in the greenhouse, the cooling load calculation formula based on the heat balance method was constructed and verified by the actual cooling load measured in the fog cooling greenhouse. To examine the ventilation heat transfer in the cooling load calculation formula, we measured ventilation rates in the experimental greenhouse which a cooling system was not operated. The ventilation heat transfer by a heat balance method showed a relatively good agreement. Evaporation efficiencies of the two-fluid fogging system were a range of 0.3 to 0.94, average 0.67, and it showed that they increased as the ventilation rate increased. We measured thermal environments in a fog cooling greenhouse, and calculated cooling load by heat balance equation. Also we calculated evaporative cooling energy by measuring the sprayed amount in the fogging system. And by comparing those two results, we could verify that the calculated and the measured cooling load showed a relatively similar trend. When the cooling load was low, the measured value was slightly larger than calculated, when the cooling load was high, it has been found to be smaller than calculated. In designing the greenhouse cooling system, the capacity of cooling equipment is determined by the maximum cooling load. We have to consider the safety factor when installed capacity is estimated, so a cooling load calculation method presented in this study could be applied to the greenhouse environmental design.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.6
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• pp.1325-1331
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• 2007

In order to investigate the cooling capacity of an air-conditioner applying a variable capacity compressor and the temperature characteristics on a condenser and an evaporator, the experiment on the operation characteristics of the air-conditioner was performed along a compressor operation ratio and an indoor/outdoor temperatures, under a cooling operation mode. The system characteristics were measured by the psychrometric calorimeter. The cooling capacity increased with decreasing the outdoor temperature and increasing the indoor temperature. Also, it increased with increasing the compressor operation ratio. The temperature of the condenser was more sensitive for the variation of the outdoor temperature and the temperature of the evaporator was more sensitive for the variation of the indoor temperature. The operation characteristics of the cycle used in this present were also analyzed by a pressure-enthalpy chart.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.27 no.6
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• pp.533-540
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• 1998

최근에 국내외 에너지 이용 효율성 증대 문제, CFCs등으로 인한 오존층 파괴문제, $CO_2$ 등으로 인한 지구온난화 문제, 실내공기질(IAQ)과 관련된 건물 환기량 증대요구로 인한 건물용 공조시스템(HVAC)의 설계변경 문제 등으로 인해 다양한 종류의 대체 냉방기기가 연구되어 오고 있다. 현재 미국에서는 ASHRAE Standard 62-1989에 의해 실내거주자의 필요한 IAQ와 쾌적함을 유지하기 위해 환기량을 기존의 경우보다 약 3배 이상이 되도록 권장하고 있고 또한 대다수의 미국 주 정부에서 건물설계에 관련된 조례로 ASHRAE Standard 62-1989를 적용하고 있다. 따라서 빌딩공조 설비관계자들은 늘어난 환기 요구량에 따라 잠열냉방용량이 크게 증대되므로 이를 처리하기 위한 새로운 냉방공조기기 시스템기술에 대해 관심이 증대하고 있다. 이에 따라 건조제를 x이용한 냉방 및 제습 시스템이 대체 냉방시스템 또는 기존의 냉방 시스템과 더불어 잠열부하를 처리하는 복합 시스템으로 최근에 다시 상당한 주목을 받고 있다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.10
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• pp.4308-4313
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• 2011

The objective of this study is to investigate the cooling performance of the roof mounted air-conditioning system using electric driven scroll compressor for zero emission vehicles. This air conditioner with air source was used R-134a as a refrigerant and tested under various operating conditions such as refrigerant charge amount and indoor temperature, and compressor frequencies. Experimental results revealed that at all tested compressor frequencies, heat transfer rate of the evaporator increased and the cooling COP increased with the indoor temperature. In addition, the heat transfer rate of the evaporator was over 25.0kW sufficient for the cooling loads of an electric bus.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.5
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• pp.413-421
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• 2014

Desiccant cooling system is an air conditioning system that uses evaporative cooler to cool air and it can perform cooling by using heat energy only without electrically charged cooler. Thus, it can solve many problems of present cooling system including the destruction of ozone layer due to the use of CFC[chloro fluoro carbon] affiliated refrigerants and increase of peak power during summer season. In this study, cooling performance and exergy analysis was conducted in order to increase efficiency of desiccant cooling system. Especially, using exergy analysis based on the second law of thermodynamics can resolve the issue related to system efficiency in a more fundamental way by analyzing the cause of exergy destruction both in whole system and each component. The purpose of this study is to evaluate COP[coefficient of performance], cooling capacity and exergy performance of desiccant cooling system incorporating a regenerative evaporative cooler in various regeneration temperature and outdoor air conditions.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.426-430
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• 2008

Though the air-conditioners in each train model have almost identical function, there is incompatibility between them because of their different electric capacity and parts, even spares manufactures are different in the manufactured year. It cause over cost in the maintenance and repair of the each air-conditioner. In this paper, all the air-conditioners in each train model have been classified by their capacity and features so that grasp the operation status and the repair process of the air-conditioners, and draft systematically cost-effective solutions. By finding a way to deal with the emergency repair and extending the air-conditioner life though improvement of checking up progress, increase of passenger revenue can be reached considerably.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.17-24
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• 1998

압축기의 종류는 크게 dynamic type과 positive displacement type으로 우선 나눌 수 있다. 전자는 제트엔진에 사용되는 압축기에서 보는 바와 같이 기체의 속도를 변화시켜 동압을 정압으로 바꾸어 압력을 얻는 경우이다. 후자는 기체를 둘러싼 체적을 줄여서 압력을 얻는데 가전제품에 쓰이는 냉각용 압축기의 대부분의 종류가 이에 해당된다. 압축 기체의 종류에 따라 공기 압축기, 가스 압축기, 냉각용 압축기로도 나눌 수 있겠다. 냉각용 압축기는 다시 여러 가지 방법으로 분류할 수 있겠지만, 구동 모타의 용량이나 냉각 용량에 따라, 대형, 소형으로 분류하거나, 압축기를 둘러싼 셀의 구조에 따라 밀폐형과 반 밀폐형으로 나눌 수 있다. 밀폐형은 냉매를 반 영구적으로 보충할 필요가 없도록 용접형 셀을 가진 구조로 압축기를 다시 열어서 보수할 수가 없다. 냉장고나 냉방기 같은 가전 제품에 쓰이는 압축기는 대부분 소형 밀폐형이 되겠다. 산업용의 중,대형 압축기는 보수의 목적으로, 자동차 냉방용 압축기는 동력이 엔진축에서 공급되는 구조 상의 이유로 반 밀폐형이 채택된다. 보수가 사실상 불가능한 밀폐형의 구조 상 소형 냉장용 압축기는 거의 무한 수명을 감안한 설계를 요하게 되고, 이것이 압축기의 보수적인 설계 및 개발 성향에 어느 정도 영향을 주었다고 볼 수 있다. 이런 소형 밀폐형 압축기(positive displacement, fractional horsepower, hermetic compressor)에 관한 연구의 소개가 이 글의 주 관심이 되겠다. 압력을 얻기 위해 체적을 변화시키는 mechanism도 여러 가지가 있는 바, 왕복동식 피스톤(reciprocating piston) 압축기가 가장 오랫동안 사용되어 온 구조이다. 회전식으로 압축을 얻는 방식으로는 로타리 피스톤식, 스크류식, 스크롤식 압축기가 있다. 로타리 피스톤(rotary piston)식 압축기는 약 20여년 전 부터 냉방용 압축기에서부터 널리 쓰이게 되었다. 약 10여년전부터 상용화 된 스크롤(scroll) 형 압축기도 현재 상대적으로 용량이 큰 가정용 냉방기를 중심으로 많이 쓰이고 있다. 스크류형 압축기는 보통 중대형 상업용에 주로 쓰인다.