• 한국수소및신에너지학회논문집
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• 제20권1호
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• pp.31-37
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• 2009

An ejector is a machine utilized for mixing fluid, maintaining a vacuum, and transporting fluid. The Ejector enhances system efficiency, are easily operated, have a mechnically simple structure, and do not require a power supply. Because of these advantages, the ejector has been applied to a variety of industrial fields such as refrigerators, power plants and oil plants. In this work, an ejector was used to safely recycle anode tail gas in a 5 kW Molten Carbonate Fuel Cell system at KEPRI(Korea Electric Power Research Institute). In this system, the ejector is placed at mixing point between the anode tail gas and the cathode tail gas or the fresh air. Commercial ejectors are not designed for the actual operating conditions for our fuel cell system. A new ejector was therefore designed for use beyond conventional operating limits. In this study, the entrainment ratio is measured according to the diametrical ratio of nozzle to throat in the designed ejector. This helps to define important criteria of ejectors for MCFC recycling.

• 조명전기설비학회논문지
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• 제21권4호
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• pp.88-95
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• 2007

Korea is highly dependent on foreign countries for energy while at the same time having a high energy-consumption industrial structure. Therefore, logical improvements in energy use efficiency and nationwide energy saving are becoming more and more important in coping with the worldwidehigh oil prices and environmental issues such as listed in the Kyoto Protocol to the United Nations Framework Convention on Climate Change. Consequently, a study was conducted on the average annual load factor in domestic areas to set a reasonable and reliable technology standard plan for high-efficiency transformers. The average annual load factor in Korea was discovered to be 18.4[%] classified by industry. This factor is expected to be used in arranging a domestic standard for a minimum efficiency system for transformers, and in reviewing and supplementing the standard transformers plan for the High Energy-Efficiency Appliance Certification. The expected effect from the establishment of the technology standards plan for highly efficient transformers is the expansion of the manufacturing and distribution of highly efficient transformers that are suitable for domestic use. These will lead to electricity cost savings for users, strengthening the related industries' market competitive powers and the effective reduction of greenhouse gases on a national level by drastically reducing loss from transformers, which accounts for a large portion of the total electric supply losses.

• 한국항해항만학회지
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• 제28권1호
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• pp.83-90
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• 2004

경비, 훈련, 지원 등의 해상 임무를 종료한 해군 함정은 차기 임무를 준비하기 위해 모항에 입항하여 긴급수리, 유류수급, 무장 적하역, 크레인, 태세유지, 수리, 포 배열, 탄약적재, 부식 작업 등의 일련의 서비스를 필요로 한다. 본 연구에서는 한정된 선석과 설비 자원 하에서 여러 함정에 대한 효율적인 선석 할당 계획의 수립을 목적으로 한다. 이를 위해 불필요한 선석이동을 줄이고 계획기간 동안 각 함정이 필요로 차는 서비스를 점수화한 총점을 최대화하는 기존의 모형을 토대로, 서비스 지속 기간이 제한적이고 서비스들 간의 전후 우선순위가 존재하는 현실적인 제약을 고려하면서 전비태세를 향상시킬 수 있는 혼합 정수 계획 모형(Mixed Integer Programming)을 수립해 보았다. 효과적인 분석을 위하여 ILOG OPL(Optimization Programming Language) Studio 3.1을 사용하여 모델링 한 후 ILOG CPLEX 7.0으로 최적해를 구해 보았다. 본 연구에서 제시한 모형이 해군 함정의 효율전인 선석 할당 계획 수립에 적용될 수 있다면 해군 부대의 전비태세 향상에 기여를 할 수 있을 것으로 생각된다.

• 한국분무공학회지
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• 제19권3호
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• pp.115-122
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• 2014

As a demand for an automobile increases, air pollution and a problem of the energy resources come to the fore in the world. Consequently, governments of every country established ordinances for green-house gas reduction and improvement of air pollution problem. Especially, as international oil price increases, engine using clean energy are being developed competitively with alternative transportation energy sources development policy as the center. Bio ethanol, one of the renewable energy produced from biomass, gained spotlight for transportation energy sources. Studies are in progress to improve fuel supply methods and combustion methods which are key features, one of the engine technologies. DI(Direct Injection), which can reduce fuel consumption rate by injecting fuel directly into the cylinder, is being studied for Green-house gas reduction and fuel economy enhancement at SI(Spark Ignition). GDI(Galoine Direct Injection) has an advantage to meet the regulations for fuel efficiency and $CO_2$ emissions. However it produces increased number of ultrafine particles, that yet received attention in the existing port-injection system, and NOX. As fuel is injected into the cylinder with high-pressure, a proper injection strategy is required by characteristics of a fuel. Especially, when alcohol type fuel is considered. In this study, we tried to get a base data bio-ethanol mixture in GDI, and combustion for optimization. We set fuel mixture rate and fuel injection pressure as parameters and took a picture with a high speed camera after gasoline-ethanol mixture fuel was injected into a constant volume combustion chamber. We figured out spraying characteristic according to parameters. Also, we determine combustion characteristics by measuring emissions and analyzing combustion.

• 한국대기환경학회지
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• 제34권1호
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• pp.76-86
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• 2018

Using the CAPSS emissions data, we analysed changes and reasons in the annual air pollutant emission trends from 1999 to 2014. The CO emissions in the metropolitan area decreased steadily since 2001, when the latest model year of automobiles and high efficiency fuel were applied. However, other regions have not changed significantly in annual emissions. $NO_x$ emissions continued to increase since 2003, and unchanged after the decline in 2007. $SO_x$ emissions are steadily declining due to the supply of low sulfur oil. The $PM_{10}$ and $PM_{2.5}$ emissions were repeatedly affected by the influence of motor vehicles activities in the metropolitan area. In Gangwon and Chungcheong Provinces, emissions are increasing according to the use of coal in the manufacturing sector. And VOC and $NH_3$ emissions are increasing steadily every year. The major CO emission sources was automobiles in the metropolitan area. However, agricultural residue burning was the biggest CO sources in the Chungchong, Honam and Yeongnam Provinces. The major sources of $NO_x$ emissions differ from region to region. In the Metropolitan area, Honam and Yeongnam region, the truck was the largest emitter of $NO_x$. However, the cement kiln was the largest producer of $NO_x$ in Gangwon region, and the power plant is the largest emitter in Chungcheong Provinces.

• 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.

• 한국자동차공학회논문집
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• 제20권2호
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• pp.123-134
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• 2012

A typical cooling system of an engine relies on a water pump that circulates the coolant through the system. The pump is typically driven by the crankshaft through a mechanical link with engine starting. In order to reduce the friction and warm-up time of an engine, the clutch-type water pump (CWP) was applied in 2.0 liter diesel vehicle. The clutch-type water pump can force cooling water to supply into an engine by the operation of an electromagnetic clutch equipped as the inner part of pump system. The onset of CWP is decided by temperature of cooling water and engine oil. And, the control logic for an optimal operation of the clutch-type water pump was developed and applied in engine and vehicle tests. In this study, the warm-up time was measured with the conventional water pump and clutch-type water pump in engine tests. And the emission and the fuel consumption were evaluated under NEDC mode in vehicle tests. Also, tests were carried out for the various temperature conditions starting the operation of CWP. From the results of the study, the application of CWP can improve the fuel consumption and $CO_2$ reduction by about 3%.

• 자원ㆍ환경경제연구
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• 제24권1호
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• pp.109-139
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• 2015

현행 국가통계인 에너지밸런스 표는 우리나라 에너지 부문의 현황파악의 기초지표임에도 불구하고 IEA 기준의 에너지밸런스 표와 체계 및 수치상의 큰 차이가 있다는 선행연구를 근거로, 본 연구에서는 서로 다른 통계체계를 갖는 2009년 에너지경제연구원(KEEI) 기준의 에너지밸런스 표와 국제에너지기구(IEA) 기준의 에너지밸런스 표의 비교를 위한 기초적인 틀을 마련하고, 그 구체적인 차이를 백분율 값으로 비교 분석하여 보았다. 에너지원별, 세부 용도별로 그 구체적인 차이를 산정해 본 결과, 1차에너지공급과 에너지전환에서 에너지유가 32% 이상의 큰 차이가 나타났고, 최종에너지소비에서는 비에너지의 납사가 석유 화학에서 14.58%의 차이를 보이고 있는 등 최종에너지소비 기준으로 KEEI 에너지밸런스 통계가 IEA 통계에 비해 3.58% 크게 나타남을 확인하였다. 에너지통계는 이를 기반으로 하는 연구 및 정책 결정에 중요한 기초자료가 된다는 점에서 추가 연구와 개선을 위한 대책 마련이 필요해 보인다.

• 한국에너지공학회:학술대회논문집
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• 한국에너지공학회 2004년도 춘계 학술발표회 논문집
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• pp.341-346
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• 2004

국가의 다양한 전력생산시스템 (원자력, 석탄, 중유, LNG, 수력 발전원 등)에 대한 사회적 영향을 종합적으로 비교하기 위하여 고려된 평가항목으로서 산업적 경제성, 개인적 보건영향 (리스크), 환경영향 및 국가차원의 기여도 등이 선택되었다. 각 평가항목은 특히 발전단가, 추정사망 자수, 이산화탄소 배출량, 연료수급 안정성 등에 의하여 대표되었다. 이러한 다기준 의사결정문제의 평가방법을 개발하기 위한 예비적 연구단계로서 방사형 차트를 이용한 표현방법을 도입하였다. 이 연구에서는 이러한 사회적 영향 다이어그램을 이용하여 각 발전원의 사회적 영향의 다른 점을 쉽게 가시화 할 수 있었다. 이 연구결과에 기초하여 정성적/정량적 종합비교 방법론이 개발될 예정이다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.179-184
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• 2011

The development of new energy has attracted consideration attention due to the high oil price and environmental problems. In advanced country, they have tried to carry out a long range plan for energy. We need to develop new energy for Low Carbon Green Growth in Korea. The building is 30% among ratio of energy consumption in Korea. And in the past, heating energy was high ratio for energy using at home. But recently, the demand for cooling energy keeps growing due to rising average temperature on the earth and improvement of life quality. In this situation, the energy of lake water and ocean water has studied to utilize in advanced country because of low temperature at underwater. But the study for deep water is still a lot left to do. In this study, we analyzed district cooling system and the present condition. Analyzing the deep lake water cooling system in Toronto, we found an application of district cooling system using deep ocean water. Deep lake water uses heat source for district cooling and water source for city in Toronto. So reducing the initial cost, this city had economic effect. When DLWC was applied at existing building, the heat exchanger was installed instead of cooling tower and refrigerator. And the heat exchanger used to connect main pipe with cool water on city. System using deep ocean water can be applied as a similar way to supply cool water from lake to building.