• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.933-937
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• 2006

Energy is motive power that makes convenient society. But, our country's energy is depending on most import. Also, energy and environmental issue are important problem in community of nations. The purpose of this study is to analysis the energy consumption and environmental load of EHP and GHP in Medium and small-scaled office building. The annual energy consumption used to cooling and heating by EHP was 10 percent more than GHP. And annual energy cost of EHP was 33 percent more expensive than GHP. But, Compared to the annual $CO_2$ emission, EHP was 6 percent less than GHP. Therefore, equipment selection should be consider environmental load as well as energy consumption and cost.

• International Journal of Air-Conditioning and Refrigeration
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• 제6권
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• pp.168-176
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• 1998

A simulation study was conducted to use city-water which is thermally regulated by unused energy as a heat source for urban dwellings. This study utilized multiple heat pump system using the city-water as a heat source and suggested a method of reducing the heat load of hot water supply. The simulation was done to calculate the energy savings at a dwelling for a year. The relation between the controlled temperature of city-water. and electric energy in all seasons was also investigated. Furthermore, it has been found that the controlled water system can lead to considerable energy savings and decrease environmental load such as sensible waste heat which otherwise would form heat islands.

• 한국환경과학회지
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• 제12권4호
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• pp.503-510
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• 2003

How to plan the energy system is one of the keys f3r constructing the Environment -Friendly City. for this reason, a great number of surveys for utilizing unused energy have conducted by a planner. In regard to unused energy, the heat from incineration plants classify as a unused energy having high-exergy-energy. From this point of view, It is studied about the plant systems providing heat to district heating & cooling(D.H.C) and producing electric power. It is divided four system models as system I (10K [kgf/cm$^2$) vapor as outlet of boiler, supply far 10K vapor and return to 60$^{\circ}C$ as supply condition of district heating), system II (30 K vapor as outlet of boiler, supply for 5t vapor and return to 60f as supply condition of district heating), system 111 (30 K vapor as outlet of boiler, supply for 85$^{\circ}C$ hot water and return to 60$^{\circ}C$ as supply condition of district heating), system IV (30 K vapor as outlet of boiler, supply for 47$^{\circ}C$ hot water and return to 40t as supply condition of district heating). The results from the upper condition of four system, System II got a proper on economical benefits and system IV calculated as benefiting on energy saving effects, and suggest indifference curve as the total evaluation method of both economical benefits and energy saving.

• 산업기술연구
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• 제27권A호
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• pp.185-193
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• 2007

The object of this study is the development of a Method which is enable to review the preliminary feasibility for co-generation system in new apartment buildings. In Korea co-generation systems have been installed in most of large industrial plants and commercial buildings which consume a large quantity of electric and heat energy, for energy saving and cutting products cost, under positive governmental supports. However for apartment buildings which consume quite a large electric and heat energy, are still remained in conventional energy supply system, and are not popular to utilize useful co-generation system. One of the major reason for these is the lack of clear and easy justification tool. In this circumstance, this study can provide a tool to verify the feasibility of co-generation in apartment buildings with this handy tools for planners and designers beforehand.

• 한국태양에너지학회 논문집
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• 제25권4호
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• pp.37-44
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• 2005

An experimental study was conducted to analyze performance of a heating system with variation of control logic of the system. The system uses a solar as heat source and composed with heat pump that uses R-22 as working fluid. The difference between the developed system and the commercially available heating system is working fluid. The solar assisted heating system which was widely distributed in the market uses water as a working fluid. It could be freezing in case of the temperature drops down under freezing point. The anti-freezing fluids such as methyl-alcohol or ethylene-glycol are mixed with the water to protect the freezing phenomena. However, the system developed in this study uses a refrigerant as a working fluid. It makes the system to run under zero degree temperature conditions. Another difference of the developed system compare with commercial available one is auxiliary heating method. The developed system has removed an auxiliary electric heater that has been used in conventional solar assisted heating system. Instead of the auxiliary electric heater, an air source heat exchanger which generally used as an evaporator of a heat pump was adapted as a backup heating device of the developed system. As results, an efficiency of the developed system is higher than a solar assisted heat pump with auxiliary electric heater. The merit of the developed system is on the performance increment when the system operates at a lower solar energy climate conditions. In case of the developed system operates at a normal condition, COP of the solar collector driven heat pump is higher than the air source heat exchanger driven heat pump's.

• 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

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 1993년도 추계학술발표회 초록집
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• pp.103-108
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• 1993

In nuclear power plants using pressurized water as the main coolant, it is necessary to maintain system pressure within operational range. During transients, the coolant shrinks and expands causing insurge and outsurge of coolant in the pressurizer. In CANDU system, the pressure is controlled mainly by the pressurizer/degasser-condenser system. In CANDU system, the control of heat transport system pressure is achieved by giving heat to the pressurizer by activating the heaters to compensate a diminution in pressure or by removing heat from the pressurizer by bleeding steam to the degasser-condenser to compensate an increase in pressure. This study aims at developing a theoretical model capable to simulate various operational transients in the CANDU primary heat transport system (PHTS), applicable to CANDU engineering simulator on real time basis.

• 한국전기전자재료학회논문지
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• 제36권6호
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• pp.620-626
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• 2023

Energy harvesting technology, which converts wasted energy sources in everyday life into usable electric energy, is gaining attention as a solution to the challenges of charging and managing batteries for the driving of IoT sensors, which are one of the key technologies in the era of the fourth industrial revolution. Hybrid energy harvesting technology involves integrating two or more energy harvesting technologies to generate electric energy from multiple energy conversion mechanisms. In this study, a hybrid energy harvesting device called TMPPEG (thermo-magneto-piezoelectric-pyroelectric energy generator), which utilizes low-grade waste heat, was developed by incorporating PVDF polymer piezoelectric components and optimizing the system. The variations in piezoelectric output and thermoelectric output were examined based on the spacing of the clamps, and it was found that the device exhibited the highest energy output when the clamp spacing was 2 mm. The voltage and energy output characteristics of the TMPPEG were evaluated, demonstrating its potential as an efficient hybrid energy harvesting component that effectively harnesses low-grade waste heat.

• 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.

• 한국세라믹학회지
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• 제54권3호
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• pp.200-204
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• 2017

Molybdenum (Mo), an electrode material of alkali metal thermal-to-electric converters (AMTEC), facilitates grain growth behavior and forms Mo-Na-O compounds at high operating temperatures, resulting in reduced performance and shortened lifetime of the cell. Mo/TiN composite materials have been developed to provide a solution for such issues. Mo is a metal that possesses excellent electrical properties, and TiN is a ceramic compound with high-temperature durability and catalytic activity. In this study, a dip-coating process with an organic solvent-based slurry was used as an optimal coating method to achieve homogeneity and stability of the electrodes. Cell performance was evaluated under various conditions such as the number of coatings, ranging from 1 to 3 times, and heat treatment temperatures of $800-1100^{\circ}C$. The results confirmed that the cell yielded a maximum power of 9.99 W for the sample coated 3 times and heat-treated at $900^{\circ}C$.