• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.688-692
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• 2005

Importance of substitute energy has been increasing due to environmental issues and lack of fossil fuels. In addition, heating cost that occupies from 30 to $40\%$ of the total production cost in Korean protected cultivation needs to be reduced for profitability and global competition. But, studying on substitute energy to solve these problems has not been activated for Korean protected cultivation. Therefore, this study was conducted to develop a geothermal heat pump system for cool ing and heat ing of greenhouses at a lower cost than conventional hot air heater and air conditioner. Fundamental test of heat transfer characteristics in soil was conducted by computer simulation and controlled tests for its verification. Based on the results of the theoretical and empirical investigations, an optimum heat pump system was developed and the performance was evaluated for practical use in a greenhouse at the Pusan Horticultural Experiment Station. The system was compared with a conventional hot air heating system through a cucumber growing test and economic feasibility analysis. Results of the application test of the geothermal heat pump showed that with an initial setting of $15^{\circ}C$ the inside temperature of the greenhouse could be maintained between 15 and $17^{\circ}C$. Results of the cucumber growing test showed that there were no significant differences in average height, leaf length, leaf width, number of nods, leaf area, dry weight and yield between the plots wi th the geothermal heat pump system and a conventional hot air heater. Economic feasibility analysis indicated that the variable cost of the hot air heater could be saved $81.2\%$ using the geothermal heat pump system. It was concluded that the geothermal heat pump system might be a pertinent heating and cooling system for greenhouses because of the low operating cost and the use of environment-friendly geothermal energy.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.638-641
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• 2008

Geothermal water at moderate temperature in a range between 30 to $50^{\circ}C$ exists sparse in surroundings. Mostly they are utilized as heat or water source at spar zones in Korea. However, a large portion of used water is discarded due to its poor recovery quality and inferior application technologies. In this research, an innovative heat pump system based on the hybrid concept that combinate compression cycle and absorption cycle was investigated mathematically. The hybrid heat pump aims to recycle various kind of the heat sources at moderate temperature including geothermal water effectively. The prime objective of the simulation is to design a compression/absorption hybrid heat pump system which can make high temperature above the level of $90^{\circ}C$ and low temperature of $20^{\circ}C$ as well at the same using $50^{\circ}C$ geothermal heat water. As a result, primitive data was provided as a basis to design a prototype 3 RT class hybrid heat pump.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.172.2-172.2
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• 2010

This study was carried out in order to reduce the installation expense of heating system for greenhouse comparing to geothermal heat pump and develope the coefficient of performance (COP) for a heat pump. For getting plenty of heat flux from geothermal energy. Surface water in river channel was used for getting a lots of geothermal heat by penetrating water through underground soil layer of the river bank that make heat transmission to passing water. The range of water temperature after the process of Ground filtration is 13~18 degrees celsius which is very similar to low heat source of geothermal heat pump system and the plenty amount of heat source from that make the number of geothermal heat exchanging hole and the expense for geothermal heat exchanger construction reduced. Drainage well is also used for returning filtration water to the aquifer that keep the water good recirculation from losing geothermal heat and water resource. For the COP improvement of Heat pump, thermal storage tank with separating insulation plate according to the temperature difference make the COP of Heat pump that is similar to thermal storage tank with diffuser. Developed thermal storage tank make construction expense cheaper than customarily used one's. and that sand filter and oxidation sand (FELOX) are going to be used for improving ground filtration water quality that make heat exchanger efficiency better. All above developed component skill are going to be set on the Ground filtration water source heat pump system and applied for medium, large scale for protected greenhouse in riverside area and on-site experiment is going to do for optimizing the heating system function and overcome the problem happening in the process of on-site application afterward.

• Journal of Biosystems Engineering
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• v.32 no.1 s.120
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• pp.30-36
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• 2007

Geothermal heat pump systems use the earth as a heat source in heating mode and a heat sink in cooling mode. These systems can be used for heating or cooling systems in farm facilities such as greenhouses for protected horticulture, cattle sheds, mushroom house, etc. A horizontal type means that a geothermal heat exchanger is laid in the trench buried in 1.2 to 1.8 m depth. Because a horizontal type has advantages of low installation, operation and maintenance costs compared to a vertical type, it is easy to be adopted to agriculture. In this study, to heat and cool farm facilities and obtain basic data for practical application of horizontal geothermal heat pump systems in agriculture, a horizontal geothermal heat pump system of 10 RT scale was installed in greenhouse. Heating performance of this system was estimated. The horizontal geothermal heat pump used in this study had heating COP of 4.57 at soil temperature of 14$^{\circ}C$ for depth of 1.75m and heating COP of 3.75 at soil temperature of 7$^{\circ}C$ for the same depth. The stratification of water temperature in heat tank appeared during the whole heat rejection period.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1249-1254
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• 2008

Industrial low temperature waste heat exists sparse in surroundings but its amount is huge. However, large portion of waste heat is discarded due to its poor recovery quality and inferior application technologies. The heat pump system in this research is based on the hybrid combination of compression cycle and absorption cycle in order to recycle various kind of industrial waste heat effectively. The prime objective is to design a compression absorption hybrid heat pump system which can produce high temperature above the level of $90^{\circ}C$ and low temperature of $20^{\circ}C$ at the same time using waste heat water of $50^{\circ}C$. A mathematical simulation was carried out as a basis to design a prototype 3 RT class hybrid heat pump. From the simulation results, fundamental parameters to design the system were obtained.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.10 no.2
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• pp.19-23
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• 2014

In the capital of Mongolia where the air quality is getting worse due to the coal consumption used for electricity generation and district heating, the application of geothermal systems in the housing sector is recently designed for high class resort. In this study, the case of applying a geothermal system in a house in Mongolia is examined. The effects of passive house design on the needed heat pump capacity, as well as the annual energy consumption are analyzed. Moreover, as the initial costs, except labor fee, are assumed similar to Korea, cost analysis for several cases is examined, too. From the results, if a house is designed according to passive house standard instead of ASHRAE standard, the heat pump capacity can be expected to be reduced from 16 to 5~6 RT. Furthermore, although the initial cost of architectural cost might increased by 29 M\, the total initial cost is reduced by 14 M\, while the annual energy consumption is reduced by 14%. This is mainly driven by the fact that the geothermal system which serves as the main system to cover the building needs, with a high initial cost for fulfilling the peak requirements.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.209-214
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• 2006

In this study, application of groundwater thermal energy by use of riverbank filtration(RBF) system is reviewed and checked as an energy resources. Also, the cooling and heating system using RBF was developed in Chang-Won Waterwork site to examine the feasibility in real operation of the system. We estimates the roughly overall energy obtained from RBF system if the system is used in cooling and heating. The water temperature and room temperature have been monitored to evaluate the efficiency of the system and the preliminary results show that the geothermal energy obtained by RBF could be adopted in cooling and heating energy source efficiently.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.14 no.3
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• pp.15-20
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• 2018

To study the effects of solar energy in a greenhouse, outdoor air temperature and wind speed on inside air temperature, a simulation model for forecasting the greenhouse air temperature was conducted on the basis of the energy and mass balance theory. Application of solar energy to the greenhouse is major area in the renewable energy research and development in order to save energy. Recently, considering the safety and efficiency of the heating of greenhouse, clean energy such as geothermal and solar energy has received much attention. The analysed greenhouse has $50m^2$ of ground area which located in jocheon-ri of Jeju Province. Experiments were carried out to collect data to validate the model. The results showed that the simulated air temperature inside a plastic greenhouse agreed well with the measured data.

• International Journal of Computer Science & Network Security
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• v.22 no.12
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• pp.178-184
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• 2022

Renewable energy sources based on solar radiation, wind energy, geothermal energy, and biomass energy have now reached the level of industrial application. A new way to generate electricity using low-potential heat is to install a hydro-steam turbine. In hydro-steam turbines, hot water is supplied directly to turbine rotor nozzles without prior separation into steam and water in separators, which significantly increases the efficiency of hot water energy use. Such turbines are suggested to be used as autonomous energy sources in geothermal heating systems, heating water boilers and cooling systems of chemical reactors, metallurgical furnaces, etc. The authors conclude that the installation of hydro-steam turbines in heating plants and process boiler plants can also be effective if the used exhaust steam-water mixture at the turbine outlet is used to heat the network water or as return water.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.573-573
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• 2009

지열에너지는 지구가 생성될 당시부터 지구 내부에 존재하는 무한한 열에너지로 온실가스 배출이 적으며 태양광이나 풍력 등 다른 신재생 에너지와는 달리 일정한 에너지를 공급할 수 있는 항상성 에너지로 기저부하를 담당할 수 있다. 지열을 이용한 전력 생산은 1904년에 이탈리아 라데렐로에서 처음으로 시작되었으며, 현재까지 화산지대를 중심으로 활발히 이루어지고 있다. 2001년에서 2005년 사이에 전세계 지열발전용량은 약 13% 증가하였으며, 2005년을 기준으로 약 8,933MWe의 지열발전설비가 가동 중이다. 최근 들어 지하 심부까지 시추하여 지열저장소(geothermal reservoir)를 형성하고 이를 통해 지열에너지를 생산하는 새로운 시스템인 EGS(Enhanced Geothermal Systems)가 개발됨에 따라 비화산지대에서도 지열발전소를 건설하려는 움직임이 가속화되고 있다. EGS는 지하 심부의 불투수성 결정질 암반에 존재하는 지열에너지의 경제적인 생산뿐만 아니라 물을 주입하여 생산시키는 순환 방식을 이용하여 지열에너지 획득의 매개 역할을 하는 지열수의 고갈 문제를 해결하였다. 결정질 암반에서의 지열저장소의 형성은 암반 내에 분포하는 불연속면에서 주로 발생하며, 이를 위한 압력 조건은 현지 암반의 응력 분포 특성과 암반 및 불연속면의 물성에 좌우된다. 시추공을 통해 지하 심부의 암반에 수압이 가해지면 물의 주입으로 불연속면의 마찰력이 감소하며, 이로 인해 불연속면에 전단변형이 발생하게 된다. 전단변형은 불연속면을 열린 상태로 유지시켜 지열저장소를 형성하게 된다. 불연속면의 전단 변형시 발생하는 미소 탄성파는 시추공 주변에 설치한 모니터링 장비에서 측정되며, 모니터링 장비에 의해 측정된 미소 탄성파 발생 지점의 클러스터는 지열저장소의 공간적 분포 및 규모를 추정할 수 있는 자료가 된다. 현재 EGS를 이용한 지열발전 프로젝트는 프랑스 슐츠, 스위스 바젤, 호주 하바네로에서 대표적으로 진행 중이다. 슐츠는 현재 1.5MWe의 파일럿 플랜트를 가동 중이며, 하바네로는 파일럿 플랜트 건설 단계를 진행중이다. 스위스 바젤은 지열저장소를 형성시킬 목적으로 수행된 주입시험에서 발생된 문제에 대한 기술의 신뢰성을 확보할 목적으로 잠시 중단된 상태다. 제주도는 신생대에 분출하여 형성된 대표적인 한국의 화산지형으로 지열부존 가능성이 높을 것으로 예상되는 지역이다. 따라서 폐사는 지열에너지 부존 특성을 파악하기 위한 심부 물리 탐사 및 탐사정 시추가 실시될 예정이며 궁극적으로 국내 최초의 상용화된 지열발전소 건설을 목표로 하고 있다.