• 수산해양기술연구
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• 제31권4호
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• pp.402-412
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• 1995

본 연구의 결과를 요약하면 다음과 같다. (1) 유압 펌프, 유량조절 밸브(오리피스)등을 주된 구성 요소로 하는 구조가 간단하고, 운전.관리가 용이한 유압식 풍력.열 변환 장치를 개발하였다. (2) 실험 결과로부터 본 장치의 에너지 변환 효율이 매우 높음을 확인하였다. (3) 출력 에너지가 열 에너지이므로 온수 탱크를 사용하여 쉽게 에너지를 저장할 수 있음을 실험적으로 확인하였다. (4) 본 장치는 대량 생산되는 유압 부품들만을 사용하여 구성이 가능하므로 매우 저렴한 가격으로, 신뢰성이 우수한 장치를 제작할 수 있다

• 설비공학논문집
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• 제28권10호
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• pp.387-393
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• 2016

A ground source heat pump system maintains a constant efficiency due to its stable heat source and radiant heat temperature which provide a more effective thermal performance than that of the air source heat pump system. As an eco-friendly renewable energy source, it can reduce electric power and carbon dioxide. In this study, we analyzed one year of data from a web based remote monitoring system to estimate the thermal performance of GSHP with the capacity of 3RT, which is installed in a low energy house located in Daejeon, Korea. This GSHP system is a hybrid system connected to a solar hot water system. Cold and hot water stored in a buffer tank is supplied to six ceiling cassette type fan coil units and a floor panel heating system installed in each room. The results are as follows. First, the GSHP system was operated for ten minutes intermittently in summer in order to decrease the heat load caused by super-insulation. Second, the energy consumption in winter where the system was operated throughout the entire day was 7.5 times higher than that in summer. Moreover, the annual COP of the heating and cooling system was 4.1 in summer and 4.2 in winter, showing little difference. Third, the outlet temperature of the ground heat exchanger in winter decreased from $13^{\circ}C$ in November to $9^{\circ}C$ in February, while that in summer increased from $14^{\circ}C$ to $17^{\circ}C$ showing that the temperature change in winter is greater than that in summer.

• 한국수소및신에너지학회논문집
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• 제26권1호
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• pp.64-70
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• 2015

Organic Rankine cycle (ORC) is an useful cycle for power generation system with low temperature heat sources ($80{\sim}400^{\circ}C$). Since the boiling point of operating fluid is low, the system is used to recover the low temperature heat source of waste heat energy. In this study, a ORC with R134a is applied to recover the waste energy of condenser of coal fired power plant. A system model is developed via Thermolib$^{(R)}$ under Simulink/MATLAB environment. The model is composed of a refrigerant heat exchanger for heat recovery from coal fired condenser, a drum, turbine, heat exchanger for ORC heat rejection, storage tank, water recirculation pump and water drip pump. System analysis parameters were heat recovery capacity, type of refrigerants, and types of turbines. The simulation model is used to analyze the heat recovery capacity of ORC power system. As a result, increasing the overall heat transfer coefficient to become the largest of turbine power is the most economical.

• 한국산학기술학회논문지
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• 제21권11호
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• pp.634-640
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• 2020

전투차량의 연료탱크에 설치되어 엔진으로 연료를 이송하는 장치인 전기식 연료펌프에 대하여 고장분석과 내열성능 평가가 수행되었다. 고장의 원인을 파악하기 위하여 직류 전동기가 적용된 연료펌프를 분해하여 검사를 수행하였다. 하우징 내부를 관찰한 결과를 바탕으로 고장 현상을 권선 소손, 브러시 조기 마모, 연료 혼입의 세 가지로 분류하였다. 연료펌프 내부 검사를 실시한 결과를 바탕으로, 과열에 의한 권선 소손을 고장을 발생시킨 주된 원인으로 추정하였다. 이에 따라서 전기식 연료펌프의 권선이 과열로 소손될 가능성을 확인하기 위하여 온도 센서를 고정자 표면과 브러시 홀더에 설치한 후 무부하 조건으로 24시간동안 가동을 실시하였다. 연료펌프의 주변 온도를 68 ℃로 설정하였을 때 고정자 온도는 최대 135.9 ℃까지 상승하였으며, 전동기의 고정자 및 회전자 권선이 소손되었다. 이 결과를 통해서 전기식 연료펌프를 위한 전동기 권선의 내열성능이 부족함을 확인할 수 있었으며, 이를 해결하기 위하여 현재 155 ℃ 이하에서 사용할 수 있는 절연등급 F종의 권선 및 함침액을 180 ℃ 이상에서도 사용할 수 있는 C종 이상의 절연등급으로 대체하도록 제안하였다.

• Journal of Biosystems Engineering
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• 제27권6호
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• pp.565-572
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• 2002

In order to control the root-zone temperature of greenhouse crops in the hydroponics at hot and cold season, heat pump system for cooling and heating was built and tested in this work. The system was air-to-water type and vapour compression type. The heating and cooling mode was selected by the four way valve. Capacity of the compressor was 3.75㎾ and heat transfer area of the evaporator and the condenser were 3.05㎡ and 0.6㎡, respectively. According to the performance test, it could supply heat of 42,360 to 64,372kJ/h depending on the water circulation rate of 600 to 1,500ℓ/h, respectively, when indoor air temperature was 10∼20$\^{C}$. COP of heat pump system was 3.0 to 4.0 in the heating mode. But, COP of the cooling mode was 1.3 to 2.1 at indoor temperature of 20∼35$\^{C}$. The feasibility test in the greenhouse the developed heating and cooling system was installed, showed that the heating cost of the developed system was only about 13% of that of the conventional heating system. The heating cost of the developed system was 367won/day(electric consumption 9.7㎾h/day), while that of the conventional system was 2,803won/day(oil consumption 7.7ℓ/day) at the same heating mode.

• Agricultural and Biosystems Engineering
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• 제6권1호
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• pp.22-26
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• 2005

A wind-heat generation system was developed and the system consisted of an electric motor, a heat generation drum, a heat exchanger, two circulation pumps and a water storage tank. The heat generation drum is an essential element determining performance of the system. Frictional heat was generated by rotation of a rotor in the drum filled with a working fluid, and the heat stored in the fluid was used to increase water temperature through the heat exchanger. Effects of some factors such as rotor shape, kind and amount of working fluid, rotor rpm and water flow rate in the heat exchanger, affecting the system performance were investigated. Amounts of heat generated were varied, ranging from 126,000 to 32,760 kJ/hr, depending on combination of the factors. Statistical analysis using GLM procedure revealed that the most influential factor to decide the system performance was amount of the fluid in the drum. Experiments showed that the faster the speed of the rotor, the greater heat was obtained. The greatest efficiency of the heat generation system, electric power consumption rate vs gained heat amount of water, was about 70%. Though the heat amount was not enough for plant bed heating of a 0.1-ha greenhouse, the system would be promising if some supplementary heat source such as air- water heat pump is added.

• 한국지열·수열에너지학회논문집
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• 제17권3호
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• pp.30-40
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• 2021

This paper compares the annual energy performance of four different types of air-conditioning systems in a medium-sized office building. Chiller and boiler, air-cooled VRF, ground-source VRF, and ground-source heat pump systems were selected as the systems to be compared. Specifically, the energy performance of the GSHP system and the ground-source VRF system were compared with each other and also with conventional HVAC systems including the chiller and boiler system and air-cooled VRF system. In order to evaluate and compare the energy performances of four systems for the office building, EnergyPlus, a whole-building energy simulation program, was used. The EnergyPlus simulation results show that both the GSHP and the ground-source VRF systems not only save more energy than the other two systems but also significantly reduce the electric peak demand. These make the GSHP and the VRF systems more desirable energy-efficient HVAC technologies for the utility companies and their clients. It is necessary to analyze the impact of partial load performance of ground-source heat pump and ground-source VRF on the long-term (more than 20 years) performance of ground heat exchangers and entire systems.

• 한국수소및신에너지학회논문집
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• 제12권3호
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• pp.157-167
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• 2001

Metal hydride올 이용하는 냉방시스템은 다른 냉방시스템과 비교하여 환경 친화적이며 Clean technology라는 장점이 있다. 이러한 시스템 중에 최근에 많은 연구가 진행중인 Electric Compressor로 수소의 이동이 제어되는 Compressor-Driven Metal Hydride Heat Pump(CDMHHP)은 폐열원의 온도에 의해 제어되는 시스템에 비하여 cooling power가 크다는 장점과 함께 단속적인 냉방이 아닌 2개의 함금쌍으로도 연속적인 냉방이 가능하다는 장점이 있다. 본 연구에서는 이러한 CDMHHP system의 동작특성을 분석하기 위해서 2개의 반응관에 고용량과 solping 특성이 매우 우수한 $Zr_{0.9}Ti_{0.1}Cr_{0.55}Fe_{1.45}$ Laves phase metal hydride을 장입하여 시스템을 구성하고 cycle time, surrounding temperature, 장입 수소량, 수소이동량등의 동작조건을 최적화 한 결과 최대 cooling power가 251 kcal/kg-alloyh의 우수한 성능을 보였다.

• 설비공학논문집
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• 제26권5호
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• pp.199-205
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• 2014

The integration of FC (Fuel Cell) and GSHP (Ground Source Heat Pump) hybrid system could produce a synergistic advantage in thermal and electric way. This study intends to analyse the economical aspect of a FC integrated GSHP hybrid system compared to the conventional system which is consisted with a boiler and a chiller. Based on the hourly simulation, the study indicated that GSHP system and FC+GSHP hybrid system could reduce the energy consumption on a building. The method of the economic assessment has been based on IEA ECBCS Annex 54 Subtask C SPB(Simple Payback) method. The SPB was calculated using the economic balanced year of the alternative system over the conventional (reference) system. The SPB of the alternative systems (GSHP and FC+GSHP) with 50% initial incentive was 4.06 and 26.73 year respectively while the SPB without initial incentive of systems was 10.71 and 57.76 year.

• KIEAE Journal
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• 제17권4호
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• pp.67-74
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• 2017

Purpose: As the recent climate environment changes so rapidly, environmental problems such as hot weather and fine dust have occurred, and interest in environmental policies and technology development is increasing in countries around the world. Similarly in the Architecture, researches to reduce greenhouse gas emissions and to reduce energy application are actively conducted. Looking at previous studies, it is analyzed that the electric VRF is more energy efficient than the gas engine VRF. However, energy costs have changed due to recent price hikes and discounts on gas charges due to high electricity consumption in summer. Method: In this study, the actual building of Gas Engine VRF system was modeled using SketchUp program, and EnergyPlus was used to simulate actual building. Also, Electric VRF system was simulated, and compared with Gas Engine VRF system. Result: The total secondary energy requirement of Electric VRF system was 19.6% less than that of the Gas Engine VRF system, But when analyzing with primary energy requirement, EHP used 15.8% more energy. CO2 emissions were also estimated to be 16.9% more EHP. Energy costs were 14.8% more in Electric VRF systems, because their electricity charges are 0.6 to 160% more expensive than gas charges.