• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.64-69
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• 2009

Because of their low operating and maintaining costs, ground-source heat pump(GSHP) systems are an increasingly popular choice for providing heating, cooling and water heating to public and commercial buildings. Despite these advantages and the growing awareness, GSHP systems to residential sectors have not been adopted in Korea until recently. A feasibility study of a residential GSHP system was therefore conducted using the traditional life cycle cost(LCC) analysis within the current electricity price framework and potential scenarios of that framework. As a result, when the current residential electricity costs for running the GSHP system are applied, the GSHP system has weak competitiveness to conventional HVAC systems considered. However, when the operating costs are calculated in the modified price frameworks of electricity, the residential GSHP system has the lower LCC than the existing cooling and heating equipments. The calculation results also show that the residential GSHP system has lower annual prime energy consumption and total greenhouse gas emissions than the alternative HVAC systems considered in this work.

• 한국신재생에너지학회:학술대회논문집
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• 2007.11a
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• pp.515-518
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• 2007

Because of their low operating and maintaining costs, ground-source heat pump(GSHP) systems are an increasingly popular choice for providing heating, cooling and water heating to public and commercial buildings. Despite these ad- vantages and the growing awareness, GSHP systems to residential sectors have not been adopted in Korea until recently. A feasibility study of a residential GSHP system was therefore conducted using the traditional life cycle cost(LCC) analysis within the current electricity price framework and potential scenarios of that framework. As a result, when the current residential electricity costs for running the GSHP system are applied, the GSHP system has weak competitiveness to conven- tional HVAC systems considered. However, when the operating costs are calculated in the modified price frameworks of electricity, the residential GSHP system has the lower LCC than the existing cooling and heating equipments. The calculation results also show that the residential GSHP system has lower annual prime energy consumption and total pollutant emissions than the alternative HVAC systems considered in this work.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.4
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• pp.280-286
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• 2008

In this study, characteristics simulation of heat pump system is investigated for heating and cooling using sewage water as a heat source. A simulation program for preestimate operation characteristics of heat pump system is developed. The performance of this system is resolved by several variables and the characteristics which is based on actual air and sewage temperature data. The simulation results agree well with the experimental values of COP. In the analysis of system characteristics, the COP is changed between $3\sim5$ in winter season for heating load, $4\sim6$ in summer season for cooling load. As the results of Life Cycle Cost analysis over a 15 year life cycle, the energy cost could be reduced by 250 million won if a heat pump system was used instead of a conventional boiler and an absorbtion refrigerator on the office building.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.669-674
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• 2006

The optimal control of heat pump performance for heating mode operation was investigated. Fuzzy logic was applied to control the heating performance of heat pump system and superheat at compressor discharge was taken as a control variable. Regression model was adapted to determine the optimal points where COP is maximized. Optimization of fuzzy rule table was investigated to improve operation performance of heat pump system. Experiments were carried out using original fuzzy table and the modified fuzzy rule table for heating mode operation of heat pump system. The results show that control performance of heat pump system with the modified fuzzy rule table was better than that with the original rule table.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.12
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• pp.1175-1182
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• 2004

Installations of vertical boreholes for the ground source heat pump system are expensive to install. One way to reduce the initial cost is to increase the specific heat extraction rate of borehole system. However, as the specific heat extraction rate increases the temperature of borehole fluid decreases with the resultant lower Coefficient Of Performance in Heating(COPH) of heat pump system. The purpose of this study is to provide the basic informations about the performance of heat pump system with the specific heat extraction rate and soil thermal properties such as thermal conductivity and temperature. It is shown that the specific heat extraction rate is the most important parameter for the ground source heat pump system. To obtain the reasonable COPH value (COPH > 3) the heat extraction rate should be about 25 W/m or less. Accurate measurements of soil thermal properties are also very important to design the system properly. The effects of borehole thermal resistances are also examined in this study.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.81-82
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• 2008

고온초전도 케이블은 초전도 상태를 유지하기 위해서 반드시 액체질소를 이용한 냉각시스템이 필요하다. 액체질소는 순환펌프에 의해 케이블의 유로를 순환하고 케이블을 냉각시키게 된다. 논문에서는 초전도 케이블의 냉각시스템의 기돈 설계에 있어서 중요한 운전온도 운전압력, 열부하에 대해서 고찰하였고, 현재 국내 초전도 케이블의 연구개발에 대해 고찰함으로써 향후 초전도 케이블이 실용화되기 위해 나아가야 할 방향에 대해 제시하였다.

• 보일러설비
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• s.71
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• pp.59-67
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• 1999

이 논문에서는 태양발전과 저장을 위한 환경친화적 장치에 대하여 기술하였다. 컴퓨터 모델에 주안점을 두고 시스템의 최적 발전조건을 계산하였는데, 여기에는 작동유체 효율과 태양열 집열판의 크기와 효율 그리고 출력이 포함되어 있다. 영국과 멕시코의 기후조건들이 분석되고, 각 위도에 대한 신뢰 할만한 최근 기상자료가 컴퓨터 수치모사에 사용되었다. 결과를 보면, 연간 출력 4000kW.h를 얻기 위해서, 영국의 경우 시스템 설치에 필요한 집열 면적은 $92m^{\2}$이며, 멕시코의 경우에는 유사 모사조건하에서 동일한 출력을 얻기 위해서는 $48m^{\2}$의 집열면적이 필요하다. 터빈과 이송펌프, 발전기 등의 효율에 민감하여 약간의 효율향상이 있으면 집열 면적을 현저히 감소시킬 수 있다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.6
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• pp.1339-1345
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• 1989

본 연구에서는 앞에서 개발된 온도 제어 시스템을 더욱 소형 경량화하기 위해 서 일반 마이크로 컴퓨터 대신에 원보드 마이컴(one-board micom)을 사용하였다. 원보드 마이컴은 프로그램을 기계어로 작성해야하는 어려움이 있으나 가격이 저렴하고 주변장치가 필요없으며, 크기가 작아 제어시스템을 소형경량화 시킬수 있는 장점이 있다.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.181-186
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• 1999

화학 축열 시스템의 성능을 모사하고 이를 해석하여 시스템 성능을 최적화하기 위해서는, 반응층의 열 및 물질 전달 특성을 정확히 아는 것이 중요하다. 본 연구에서는 $Na_2$S-$H_2O$ 반응계를 사용한 화학 열펌프에 대한 연구로, $Na_2$S-팽창흑연 복합체의 열전도도와 기체 투과도를 측정하였고, 소형 시스템을 제작하여 그 성능을 평가하였다. 열전도도는 전이 일차원 열류기법을 사용하여 측정하였고, 기체 투과도는 Darcy's law를 이용하여 측정하였다. 반응층의 열전도도와 기체 투과도는 팽창흑연 지지체의 겉보기 밀도와 반응염의 함량에 따라 각각 6~48W/mㆍK, 1.1$\times$$10^{-13}$~1.0$\times$$10^{-11}$m$^2$의 범위에 있었다. 또한 소형 시스템을 구성하여 445W/kgㆍ$Na_2$S의 냉방 출력을 얻을 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.6
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• pp.592-598
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• 2015

In this study, we experimentally investigate the performance characteristics of a high-performance summer-cooling heat pump for an R410A by applying an air-cooled-type vapor-injection (VI) cycle. The devices used for the experiment consist of a VI compressor, condenser, oil separator, plate-type heat-exchanger, economizer, evaporator, and re-cooler. The experimental conditions employed for the cooling performance were divided into three cycles. First, in Cycle A, we apply a VI cycle and with no heat exchange between the evaporator outlet refrigerant and the VI cycle suction refrigerant in the re-cooler. For Cycle B, there is heat exchange, and for Cycle C, there is neither a VI cycle nor heat exchange between the evaporator outlet refrigerant and the VI cycle suction refrigerant. From the analysis results, we observe that the performance was highest in the VI cycle with heat exchange between the evaporator outlet refrigerant and the VI cycle suction refrigerant (Cycle B), while it was lowest in Cycle C without application of the VI cycle. Moreover, the cooling coefficient of Performance ($COP_C$) averaged 3.5 in Cycle B, which was 8.6% higher than the corresponding value in Cycle A, and 33% higher than that in Cycle C.