• 태양에너지
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• 제18권4호
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• pp.11-22
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• 1998

Floor panel heating system using hot water is the primary heating system of domestic residential building. This paper presents the results of performance analysis of the heat pump system with air source evaporator and single unit dual sink(SUDSk) condenser. The heat exchanger combines two separated condensers into a single condenser and the object of the SUDSk condenser is to release energy to dual sinks, i.e. air for air heating system and water for panel heating system in one single unit. Simulation program is developed for single unit dual source(SUDS) SUDSk heat pump system and some experimental data are obtained and compared with simulation results. Differences of heating capacity and COP in dual source operating mode are 7% and 8% respectively. Simulation results are in good agreement with test results. Therefore, developed program is effectively used for design and performance prediction of dual source dual sink heat pump system with SUDS evaporator and SUDSk condenser.

• 한국지진공학회논문집
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• 제17권4호
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• pp.151-157
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• 2013

In this study, an externally reinforced structural system for SMC(Sheet Molding Compound) panel water tank, designed according to the Japanese design code, is experimented to evaluate its seismic performance. The test tank is 3m long, 2m wide and 3m high, considering the capacity and size of the shaking table. The measured hydrodynamic pressures are found to be approximately 70% of the Japanese design code values. It may be partially due to the convex shape effect of the unit panels. The analytical results of externally reinforced system based on the measured dynamic water pressures are found in good agreement with the test results. If the design hydrodynamic pressures are estimated properly, the proposed analytical model for the externally reinforced water tank becomes a useful design tool and the Japanese design code is found to provide a safe design for the external frames of SMC panel water tank.

• 한국수자원학회논문집
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• 제54권2호
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• pp.135-144
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• 2021

본 논문은 근래 급속하게 진행되는 온난화가 수온의 상승과 수량 변동을 수반하여 수질에도 큰 영향을 줄 것으로 전망됨에 따라 방류량 및 수온과 오염도 지수간의 인과관계 분석을 통해 효율적인 수자원 관리 및 수질 개선을 위한 시사점을 도출하고자 하였다. 이를 위해 우리나라 주요 수계의 10개 다목적댐을 대상으로 방류량 및 수온, BOD, COD, DO 등 오염도 지수에 대해 시계열 자료를 활용하여 단위근 검정 및 공적분 검정, 그랜저 인과분석을 실시하여 방류량 보다는 수온이 오염도 지수와 더 많은 인과관계가 있어 수온의 변동이 방류량의 변동보다 오염지수에 더 영향을 미치는 것으로 분석되었다. 또한, 수질과 방류량의 인과관계가 높아 이에 따른 댐의 수량 및 수질관리가 가장 우수한 댐은 합천댐과 충주댐이었으며, 2순위 대청댐이었다. 다음으로 수질과 방류량의 인과관계가 낮은 3순위 그룹의 용담 및 안동댐, 4순위 그룹은 나머지 5개 댐으로 밝혀졌다.

• 한국유체기계학회 논문집
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• 제17권5호
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• pp.11-18
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• 2014

Chilled Beam system is the kind of water-air system which reduces the conveyance energy for air conditioning as well as allows efficient installation and comfortable indoor environment, and has been increasingly popular mainly in Europe. To effectively install such Chilled Beam system domestically, it is necessary to develop the product considering domestic climatic condition and the requirements for air conditioning system, and particularly the way to deal with condensation during operation of cooling system in summer shall be provided. In this study, the optimal design on induction structure of Chilled Beam unit was carried out through a numerical method, and the performance test for the prototype of unit was conducted in a real-scale experiment facilities of Chilled Beam unit. While the flowrate of 1st air is 101.3 CMH, the pressure in pressure chamber is 158.7 Pa and the cooling capacities of 1st air side and 2nd air side are 498.1 W and 709.5 W respectively.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.422-429
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• 2008

The objective of the present study is to develope a propultion unit cooling system for the next-generation High-speed EMU. The propulsion power control unit consists of some IGBT semiconductors. In general, those power semiconductors are very sensitive to temperatures and need a cooling system to keep them at a proper operational conditions in the range of $50{\sim}100^{\circ}C$. In this first year of study, we tried to focuss on the understanding of fundamental technologies for each of the two different cooling systems and collecting basic data for design and manufacturing for both cases. For the water cooling system, a heat sink with multi channels of liquid flow was considered and a model unit was designed and performance test was conducted. For the heat pipe cooling system, a Loop Heat Pipe(LHP) was considered as an element to transport heat from IGBT to environment air flow and a model unit was designed and performance test was conducted. The analysis using SINDA/FLUINT showed that those design parameters are good enough for the LHP to properly operate under a heat load up to around 360W.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.378-379
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• 2008

Recently, composite hollow bushings have been increasingly employed mainly from the various characteristics. Composite bushings are superior to porcelain bushings in several respects, including lighter weight, better anti-pollution and anti-explosion properties, and easer manufacturing. Filament wound GRP tubes which have various winding angle were manufactured by using a filament winding machine. This paper will show some design issues and winding condition for composite bushing. And, results show that the winding condition of composite GRP tubes can be used to improved their bending strength and pressure, For bending and pressure tested, tubes with the hybrid winding pattern show higher strength than those of unit winding pattern. Also, the influence of absorption was evaluated through such as measurement of the dye penetration test and water diffusion test, also aspects of surface state using scanning electron microscopy.

• 한국농공학회논문집
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• 제55권4호
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• pp.65-72
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• 2013

The physical, mechanical, water purification and temperature properties of fiber reinforced porous hwang-toh green roof concrete have been evaluated in this study. The effect of the depending on replacement ratio of blast furnace slag to cement was investigated such that the replacement ratio is varied to 0 % and 30 %. Also, the replacement ratios of hwang-toh were 0, 20 and 30 %. The polyvinyl alcohol fiber was used for the reinforcing fiber. A series of pH test, unit weight, void ratio, compressive strength, after purification and variation of temperature test have been performed to evaluate the performance, water purification effect and temperature properties of the fiber reinforced porous hwang-toh green roof concrete. The test results indicate that the physical and mechanical properties of fiber reinforced porous hwang-toh green roof concrete is affected by the replacement ratio of the blast furnace slag and hwang-toh contents. Results of purifying water showed that the water purification effect of porous hwang-toh green roof concrete is about 40 %. Also, the temperature properties test results indicate the green roof blocks using fiber reinforced porous hwang-toh green roof concrete have insulation and temperature reduction effect.

• 한국지반공학회지:지반
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• 제14권2호
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• pp.79-92
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• 1998

실내모형실험으로 전기비저항치와 오염된 흙의 물리적 성질과의 상관관계를 규명하기 위해서 요소분석을 수행하였다. 세가지의 모래질 구에 산업폐기물매립지의 침출수를 첨가하여 모형실험에 이용했다. 혼합토의 전기비저항치는 비저항콘을 모사한 프로브를 제작하여 측정했다. 실내모형실험에서는 흙의 함수비, 간극비. 단위중량, 함수비 및 침출수의 농도를 변화시키면서 혼합토의 전기비 저항치를 계측했다. 실험결과는 흙의 종류 및 단위중량보다는 흙의 함수비, 간극수의 전도성이 전기비저항치에 큰 영향를 미치고 있음을 알 수 있었다.

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.74-78
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• 2015

Nuclear power plant steam generator that is one of the main component has several thousands of thin tubes. And the steam generator tube is subject to damage because of the severe operation conditions such as the high temperature and pressure. Therefore periodic inspections are conducted to ensure the integrity of steam generator component. Hanul unit 3 also has been inspected in accordance with in-service inspection program and is scheduled to be replaced for exceeding the plugging rate which was recommended by manufacturer. During the steam generator replacement activity, we found several clustered porosity on inner surface of main feed water pipe. Additionally crack-like indications were found at weld interface between base material and weld of main feed water pipe. This paper describes the field experience and visual testing results for inner surface of main feed water pipes. The destructive test result had shown that these indications were porosities which were caused by manufacturing process not by operation service.

• 한국건설순환자원학회논문집
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• 제6권3호
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• pp.88-93
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• 2011

천연골재의 고갈 및 환경규제에 의한 건설용 잔골재의 수급불균형 문제를 해결하기 위해 폐기콘크리트로부터 생산된 순환잔골재의 적용성을 위한 연구들이 수행되어 왔다. 본 연구의 목적은 W/C 및 단위수량의 변화에 따른 순환잔골재를 사용한 콘크리트의 역학적 특성 및 내구성능에 관한 이해를 높이는 것이다. 또한, 순환콘크리트의 구조적 적용을 위한 기초자료를 제시하는데 의미가 있다. 특히, 순환잔골재를 100% 대체한 순환콘크리트에 대하여 W/C 및 단위수량의 변화에 따른 영향은 공기량, 슬럼프, 응결시간, 압축강도, 인장강도, 탄산화 및 염화물 침투와 같은 항목에 대한 시험결과에 의해 분석 제시되었다.