• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.99-104
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• 2017

This study evaluated the heating performance of a hybrid heat pump system. The system was installed in a $100-m^2$ greenhouse to utilize surplus solar energy. A hybrid heat pump system was installed at Jocheon-ri, Jeju Island, for an empirical evaluation of the performance. The system consists of a heat storage tank and plate heat exchangers for several heat exchanges between the greenhouse and heat pump or storage tank. The system uses R410a as the working fluid and is controlled automatically by a defined set temperature of the greenhouse. This system incorporates two kinds of heat sources: outdoor air and a storage tank that collects heat from the topside of the greenhouse. The results showed that the heating capacity was 19.9 kW in the outdoor air source mode and 21.4 kW with direct heating from hot water in the thermal storage tank. These results are very similar to those of a previous study.

• Journal of Bio-Environment Control
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• v.8 no.2
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• pp.136-146
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• 1999

A series of experiments were carried out in winter to investigate the indoor thermal environment in greenhouses with different kinds of heating systems, and characterize the energy consumption, heat transport and thermal energy efficiency of each system. By the Quantitative calculation of heat losses which transmit through the covers of greenhouse, the fundamental data of energy-saving of the particular heating system were obtained. And from the analysis of air temperature differences between indoor and outside, it was possible to select more effective energy-saving and comfortable heating system in greenhouses. The electric heater was more stable in thermal environment and cheaper in cost, since it could be used during the surplus time of electric power from 10：00 p.M. to 8：00 A.M. But the low air temperature in greenhouses besides these times resulted in a chilling problem of the crops. The heating system by hot air had the advantage to show nearly uniform temperature difference by the height above the ground. But the system had the disadvantage to require more energy consumption than the electric heating system.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.1141-1144
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• 2010

본 연구에서는 난방운전시 저온 및 착상 조건에서 히트펌프 칠러의 성능을 조사하고자 하였다. 실험은 항온항습 기능을 가진 공기엔탈피 방식의 칼로리미터와 항온수조를 사용하여 수행되었으며, 실외온도조건을 설정한 후에 히트펌프 칠러의 성능을 실험으로 측정하였다. 외기조건이 $-7^{\circ}C$에서 $-15^{\circ}C$까지 변화함에 따라 시스템의 성능과 COP는 표준온도 조건의 실험값 보다 약 48~87%까지 감소하였다. 착상 실험에서는 시간 변화에 따라 출구수온이 표준온도를 기준으로 74% 감소하였다. 본 연구로부터 히트펌프 칠러의 설계 기초자료 획득 및 신뢰성을 확인할 수 있었다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1999.07a
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• pp.320-325
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• 1999

세계기후협약으로 인하여 우리나라는 화석연료 사용량을 최소한 2010년까지 2000년 수준으로 감축시켜야할 처지에 놓여 있다. 따라서 지구 온난화의 주 요인이 되고 있는 이산화탄소 배출량을 2010년 예상배출량의 21%정도를 감축해야 하며, 경제활동은 1/4이상이 축소되는 영향을 받게 된다(차재호, 1998). 따라서 현재의 화석에너지에 의존하는 난방법은 자연에너지 또는 전기에너지 등으로 대부분이 전환되어야 할 것으로 전망하고 있다 그러나 농업에 이용되고 있는 난방에너지는 화석에너지에 집중되어 있으며, 온실, 축사, 버섯재배사 등에서 겨울철 난방에 소요되는 에너지 비용은 총경영비의 10-40%를 차지하고 있다. (중략)

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.8
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• pp.797-802
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• 2012

In this study, the potential performance enhancement in a dual heat pump system through series operation was investigated by a comparison between the performance for parallel and series operation for a heating supply temperature of $60^{\circ}C$. To compare the performance of each configuration fairly, the heat transfer surface area of the heat exchangers was fixed. The inlet temperatures and the flow rates of the heat source and the load were also fixed. In addition, the heat transfer and pressure drop characteristics of the working fluids were considered to achieve a more realistic comparison. The results show that the heating coefficient of performance (COP) of the series configuration is approximately 5% higher than that of the parallel configuration under the simulation conditions considered in the present study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.573-577
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• 2013

Heat pumps come into wide use because high energy efficiency can be obtained and diverse heat sources like geothermal heat, waste heat and air are available. It is necessary for an air source heat pump to defrost in order to remove frost on the surfaces of an outdoor heat exchanger. It is impossible for continuous heating if reverse cycle operation is used as defrosting method, furthermore it causes the degradation of COP. In this study an fin-tube heat exchanger with three rows was used as an outdoor coil. One row among three rows of the heat exchanger was used like a condenser in order to remove frost on it, the others were used as evaporator to accomplish continuous heating. Each row was switched in order from a condenser to an evaporator in specified time interval. Tests were carried out during minimum 180 minutes at the defrost-heating test condition(dry bulb temperature $2^{\circ}C$, wet bulb temperature $1^{\circ}C$) described in KS C 9306. Time-averaged COP was about 20% higher than that of conventional defrosting method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.4679-4684
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• 2013

Compared with internal combustion engine, the electric vehicle has a limitation of low driving range due to low battery capacity due to relatively low energy density. Moreover, the energy consumption rapidly increases up to 30% during winter season with operating electric heater. In this study, electric vehicle performance was evaluated using heat pump having higher energy efficiency rather than electric heater for cabin heating. Electric vehicle system and heat pump system were developed using 1-D simulation software called AMESim, the simulation result indicated that the energy consumption could be reduced approximately 66% when the electric heating system was replaced with the heat pump system. As a result, the driving range is expected to increase the similar value. This study proved the merit of heat pump for cabin heating in electric vehicle, and it could contribute to developing suitable heating method for electric vehicles.

• Plant Journal
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• v.17 no.1
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• pp.50-57
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• 2021

It is very difficult to accurately calculate efficiency of each accessory device constituting the pump system and pump efficiency by the Conventional efficiency measurement method only. Therefore, this study introduced the lastest Thermodynamic pump efficiency measurement method in the district heating pump system for the first time in Korea. As a result, data uncertainty was high by the Conventional method, but the pump and Hydraulic Coupling efficiency values applied the Thermodynamic and Conventional method parallel measurement data were able to derive meaningful results that verified the reliability and adequancy of the pump performance measurement method by performing complementary roles. In additon, as a result of applying the Thermodynamic method to the distirct heating pump system, despite the high temperature environment of up to 120 ℃, it was possible to verify the reliability of the Thermodynamic method, such as high stable data mesurement, and durability of the measurement equipment.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.4
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• pp.177-182
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• 2020

Interest in heat pumps is increasing as an eco-friendly and energy-saving heating method. In particular, in order to develop a heat pump capable of heating in a low-temperature area, research to prevent frost on the surface of the outdoor unit is increasing. In other words, when heating through a heat pump in a low-temperature area, a frost layer is formed on the surface of the outdoor unit, which lowers the heat transfer performance, thereby reducing the heating capacity. Therefore, in this study, an adsorption-type dehumidification system is attached to remove the moisture vapor of the air into the outdoor unit of the heat pump. It is believed that this study can suggest the most effective dehumidification method in low temperature regions. In addition, it is expected that a heat pump with high energy efficiency can be developed by attaching an adsorption dehumidifying system to the front of the outdoor unit of the heat pump.

• Journal of the Korea Concrete Institute
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• v.23 no.4
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• pp.521-528
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• 2011

Recently, environmental concerns and issues have become great concerns for the public. Therefore, this study is conducted with the objective of preventing energy depletion and $CO_2$ emission. PCM (Phase Change Materials) having latent heat characteristic is mixed in mortar to find a proper mix proportion. Also, the mortar properties and performances as well as a melting point of PCM when applied to air conditioning and heating conditions in at building environments were obtained by performing experiments. Also, latent heat and heat transfer characteristics were obtained from experiments by test of thermal performance to formulate temperature gradient about amount of heat transfer of PCM content using the Fourier's thermal equation. The study results can be used in the application of PCM in buildings and expected effect of air conditioning and heating energy.