• 월간 기계설비
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• no.4 s.201
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• pp.30-36
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• 2007

ESCO란 에너지 절약회사(Energy Saving Company) 또는 에너지 서비스 회사(Energy Service Company)를 뜻하는 용어로 지난 1992년 정부에서 에너지 절약을 촉진하기 위해 정책자금을 도입하면서 등장했다. 이들 기업은 정부에서 정책자금을 빌려 공장이나 아파트 등 에너지 사용자에게 에너지 절약시설을 지어주고 에너지를 줄인양만큼 투자비를 회수해 간다. 고유가가 계속되면서 에너지절약 전문기업인 ESCO 단위 사업규모가 점차 대형화되고 있다. ESCO 투자실적은 1998년 이후 에너지절약 시설 개체 사업의 급속한 증가에 힘입어 매년 급격히 성장하고 있다. 최근에는 2천억원대의 시장규모를 가지고 2005년에는 건당 평균 9.1억원이 지원된 것으로 나타났다. 에너지관리공단 자금지원팀의 자료에 의하면 ESCO투자사업 자금지원은 1993~1998년 197건에 480억원이 지원됐으나 2005년에는 202건에 1,829억원이 지원된 것으로 나타났다. 지난 2006년 9월 말 현재 ESCO투자사업 자금지원은 106건에 1,020억원이 대출 은행에 추천된 것으로 알려졌다. 또한 에스코 사업분야가 조명기기·보일러 등 단순설비 교체에서 열병합발전소·냉난방설비, 공정개선 및 폐열회수 등 복합설비 쪽으로 확대되고 있는 것으로 나타났다. 따라서 에너지 소비가 큰 화학 철강 제지 등 산업체, 대형병원, 산업단지 등이 새 에너지 절감 시스템을 도입하면 에너지 효율성 개선에 효과적인 사업이다. 본지는 지난호에 ESCO사업 현황과 투자사례를 게재하고, 이번호에는 ESCO사업 지원시책과 외국의 ESCO활동 현황 및 국내의 ESCO 투자사례를 게재할 계획이다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.30 no.4
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• pp.186-194
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• 2018

A ground-source heat pump system (GSHP) is more energy efficient than other heat-source systems because it uses annual constant underground and water temperatures. Especially, two-well geothermal systems using groundwater as the heat source can achieve higher performance than closed-loop geothermal systems. However, performance of two-well geothermal systems is decreased by occurring overflow according to scale during long-term operations. Therefore, this study presents a two-well pairing geothermal system that controls the groundwater level of a diffusion well. In addition, a two-well pairing geothermal system and an SCW geothermal system were installed, and a comparative analysis of cooling performance depending on system operation under the same load conditions was conducted. The result was that the average heat pump coefficient of performance (COP) of the two-well pairing system was 6.5, and the entire system COP was 4.3.

• 월간 기계설비
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• no.1 s.198
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• pp.35-42
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• 2007

ESCO란 에너지 절약회사(Energy Saving Company) 또는 에너지 서비스 회사(Energy Service Company)를 뜻하는 용어로 지난 1992년 정부에서 에너지 절약을 촉진하기 위해 정책자금을 도입하면서 등장했다. 이들 기업은 정부에서 정책자금을 빌려 공장이나 아파트 등 에너지 사용자에게 에너지 절약시설을 지어주고 에너지를 줄인양만큼 투자비를 회수해 간다. 고유가가 계속되면서 에너지절약 전문기업인 ESCO 단위 사업규모가 점차 대형화되고 있다. ESCO 투자실적은 1998년 이후 에너지절약 시설 개체 사업의 급속한 증가에 힘입어 매년 급격히 성장하고 있다. 최근에는 2천억원대의 시장규모를 가지고 2005년에는 건당 평균 9.1억원이 지원된 것으로 나타났다. 에너지관리공단 자금지원팀의 자료에 의하면 ESCO투자사업 자금지원은 1993~1998년 197건에 480억원이 지원됐으나 2005년에는 202건에 1,829억원이 지원된 것으로 나타났다. 지난 2006년 9월 말 현재 ESCO투자사업 자금지원은 106건에 1,020억원이 대출 은행에 추천된 것으로 알려졌다. 또한 에스코 사업분야가 조명기기·보일러 등 단순설비 교체에서 열병합발전소·냉난방설비, 공정개선 및 폐열회수 등 복합설비 쪽으로 확대되고 있는 것으로 나타났다. 라서 에너지 소비가 큰 화학 철강 제지 등 산업체, 대형병원, 산업단지 등이 새 에너지 절감 시스템을 도입하면 에너지 효 율성 개선에 효과적인 사업이다. 지는 이번호에 ESCO사업 현황과 투자사례를 게재하고, 다음호에는 ESCO사업 지원시책과 외국의 ESCO활동 현황 및 국내의 ESCO 투자사례를 게재할 계획이다.

• Journal of Hydrogen and New Energy
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• v.21 no.2
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• pp.111-116
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• 2010

In this study, the structural analysis was performed to optimize the membrane humidifier with hollow fiber membrane for polymer electrolyte membrane fuel cell system. The main design factors were considered by evaluating the humidifying performance according to various structural parameters such as packing density and length. The effects of operation conditions of membrane humidifier were also elucidated experimentally. Results imply that there are optimum points for the packing density and length of humidifier. It was also found that among operation conditions, relative humidity of wet exhaust gas and temperature of dry inlet gas have major effects on the humidifying performance.

• International Journal of Fluid Machinery and Systems
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• v.3 no.1
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• pp.58-66
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• 2010

A steam control valve is used to control the flow from the steam generator to the steam turbine in thermal and nuclear power plants. During startup and shutdown of the plant, the steam control valve is operated under a partial flow conditions. In such conditions, the valve opening is small and the pressure deference across the valve is large. As a result, the flow downstream of the valve is composed of separated unsteady transonic jets. Such flow patterns often cause undesirable large unsteady fluid force on the valve head and downstream pipe system. In the present study, various flow patterns are investigated in order to understand the characteristics of the unsteady flow around the valve. Experiments are carried out with simplified two-dimensional valve models. Two-dimensional unsteady flow simulations are conducted in order to understand the experimental results in detail. Scale effects on the flow characteristics are also examined. Results show three types of oscillating flow pattern and three types of static flow patterns.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.6
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• pp.40-44
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• 2014

In this paper, maximum power is the lowering device using the facility's energy use and peak load electricity through analyzing attitude should like to make it reduce its power base rate. Simulator to manage the demand for power, a maximum electric power base power from electronic watt-hour meters by a device's signal, predictive power, the current power by computing the goal of power for less than Maximum peak power and peak shift, so that you can manage, and peak York, which role you want a cut Metal heat treatment result which analyzes the data, demand for electricity company over the years of analyzing the characteristics of each load, and effects and Reducing power consumption device every month identified seven Sequence control to the load system and successful power control is about showing that the defined goals.

• Journal of Power Electronics
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• v.16 no.1
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• pp.153-162
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• 2016

Given their structural arrangement, photovoltaic (PV) modules exhibit parasitic capacitance, which creates a path for high-frequency current during zero-state switching of the converter in transformerless systems. This current has to be limited to ensure safety and electromagnetic compatibility. Many solutions that can minimize or completely avoid this phenomenon, are available. However, most of these solutions are patented because they rely on specific and often complex converter topologies. This study aims to solve this problem by introducing a solution based on a classic converter topology with an appropriate modulation technique and passive filtering. A 5.5 kW single-phase residential PV system that consists of DC-DC boost stage and DC-AC H-bridge converter is considered. Control schemes for both converter stages are presented. An overview of existing modulation techniques for H-bridge converter is provided, and a modification of hybrid modulation is proposed. A system prototype is built for the experimental verification. As shown in the study, with simple filtering and proper selection of switching states, achieving low leakage current level is possible while maintaining high converter efficiency and required energy quality.

• International Journal of Automotive Technology
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• v.4 no.3
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• pp.149-156
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• 2003

This paper is concerned with the energy absorption efficiency of auto-body side structures for the conventional steel and 60TRIP high strength steel. In order to evaluate the energy absorption efficiency, the dynamic crash analysis is carried out with the regulation of US-SINCAP. The analysis adopts the Johnson-Cook model for the dynamic material properties, which have been obtained from dynamic material tests. For the sake of the dynamic material properties, the analysis has been accurately peformed for the crashworthiness assesment. The analysis result provides deformed shapes, amounts of penetration and accelerations at several important points during crash. The result confirms that 60TRIP greatly improves the crashworthiness of the side members without sacrificing the weight and thus can be used for the light-weight design of an auto-body.

• Journal of Radiation Industry
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• v.2 no.3
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• pp.141-148
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• 2008

Beta rays emitted from tritium in titanium tritide film were simulated with cathode rays of a scanning electron microscope to investigate the effect of beta rays from tritium on semiconductor devices. The cathode ray currents, which vary with the change of applied energy and beam spot size, were measured with Faraday cup. The current from the semiconductor device irradiated with cathode rays at various conditions was measured. The cathode ray current increased with the increase of spot size to a maximum then decreased when the spot sized increased further. The magnitude of current produced in the semiconductor device is proportional to the magnitude of cathode ray current. The magnitude of cathode ray current at each energy level was matched to the intensity of beta ray to simulate the tritium beta ray spectrum. Then the semiconductor characteristics were analyzed with I-V curves.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.1
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• pp.65-74
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• 2008

In Korea, air source heat pump system is less efficient than conventional heat source facilities, such as ground source, river water, because the air temperature in winter season is so low that COP of air source heat pump system drops below 3.0. Therefore, the study on the application of heat pump heating and cooling systems is crucial for the efficient popularization of heat pump. In this work, we present the dynamic analysis of energy consumption for the large resident building by heat resistance-capacitance method. The system simulation of water storage air source heat pump is additionally performed by changing of sizes and locations of the hospital building. The computed results show that energy cost of water storage air source heat pump is low, so it is more economical than absorption chiller & heater.