• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3407-3412
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• 2007

The performance characteristics of the polymer electrolyte fuel cells (PEFCs) were investigated under various humidification conditions at steady-state and transient conditions. The PEFC studied in this study was characterized by I-V curves in potentiostatic mode. The I-V curves representing steady-state performance were obtained from OCV to 0.25V, and the dynamic performance responses were obtained at some points of voltages. The anodic external humidification was applied and the humidity was controlled from 20% to 100%. The effects of relative humidity of hydrogen were measured with the dry air at the cathode. At high voltage region, the performance at high temperature was higher, but at low voltage region, low temperature condition showed the higher performance. The dynamic responses were observed at the instant when the voltage of the PEFC was changed. It was observed that the performance reached steady-state earlier with the increase of temperature.

• 설비공학논문집
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• 제22권12호
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• pp.821-827
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• 2010

Study on the performance characteristics of the solar hybrid system with heat pump operating temperature during winter season has performed by using an experimental test. The system performance and operating characteristics with the heat pump operating temperature, hour and load condition were investigated and analyzed. As a result, the hot water temperature was significantly affected by the heat pump operating temperature at the morning(time 1) and noon(time 2). However, hot water temperature was set by the radiation quality and collecting operation hour at the afternoon(time 3). In addition to the solar fraction was decreased for the high heat pump operating temperature because the heat pump operated with a long operating time and short operating period.

• Corrosion Science and Technology
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• 제7권1호
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• pp.61-67
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• 2008

In this paper, electrochemical and microstructural characteristics of nickel-plated Alloy 600 were investigated in order to identify the performance of electroless Ni-plating on Alloy 600 in high-temperature aqueous condition with the comparison of electrolytic nickel-plating. For high temperature corrosion test of nickel-plated Alloy 600, specimens were exposed for 770 hours to typical PWR primary water condition. During the test, open circuit potentials (OCP's) of all specimens were measured using a reference electrode. Also, resistance to flow accelerated corrosion (FAC) test was examined in order to check the durability of plated layers in high-velocity flow environment at high temperature. After exposures to high flow rate aqueous condition, the integrity of surfaces was confirmed by using both scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). For the field application, a remote process for electroless nickel-plating was demonstrated using a plate specimen with narrow gap on a laboratory scale. Finally, a practical seal design was suggested for more convenient application.

• 해양환경안전학회지
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• 제17권4호
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• pp.413-418
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• 2011

최근 화석에너지의 남용으로 인한 지구온난화문제가 인류가 해결해야 할 지상과제로 대두되고 있으며, 본 연구는 이러한 에너지문제의 해결에 도움이 될 수 있는 고온축열탱크의 개발과 그 성능특성에 관한 내용이다. 지금까지 이에 관한 연구는 그다지 활발하지 않았으며, 특히 고온축열탱크에 관한 연구는 매우 드문 실정이다. 본 연구의 목적은 비교적 열물성이 양호하며 가격이 저렴한 물질인 MgO를 현열축열재로 사용하는 고온축열탱크의 개발이다. 이를 위하여 분말 상태의 MgO를 이용하여 축열벽돌을 제작하고, 실험적 방법을 통하여 MgO를 축열재로 사용하는 고온축열탱크의 성능특성에 관하여 연구하였다. 본 연구를 통하여 현열축열재인 MgO의 고온축열 및 방열성능을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제37권6호
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• pp.582-588
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• 2013

고체산화물형 연료전지는 높은 효율과 친환경적 특성을 가지고 있어 선박에 의한 대기 오염의 주 원인인 디젤 엔진을 대체할 수 있는 동력원으로 주목 받고 있다. 고체산화물형 연료전지의 높은 작동 온도는 고효율과 다양한 연료를 사용할 수 있고 고가의 촉매를 사용하지 않아도 되지만 고열에 의한 시스템의 손상이 발생할 수 있다. 따라서 고성능과 신뢰성을 확보하기 위해 온도제어기가 설계되어야 하고 시스템에 적용하기 전 제어기의 성능이 검증되어야 한다. 본 연구에서는 많은 비용과 시간을 필요로하는 전통적인 제어기 성능 검증 방식 대신에 Hardware-In-the-Loop Simulation 방식을 활용한 성능 검증 시스템을 개발하였고 고체산화물형 연료전지 시스템에 대한 온도제어기의 성능을 검증하였다.

• KSTLE International Journal
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• 제2권2호
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• pp.120-126
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• 2001

Performance requirements for automatic transmission fluids have been changed reflecting the design changes of automatic transmissions. The major purpose of these design changes is concentrated upon improvements of both fuel economy and drivability. In order to formulate such high performance ATFs as satisfy those requirements, it is necessary to use high quality base oils like VHVI base oils and PAOs. In this study, the effect of base oils characteristics on ATF performance is investigated, mainly regarding differences in frictional characteristics with deterioration. Frictional characteristics are determined using the SAE No. 2 machine and ATFs are deteriorated under various controlled conditions. Moreover low-temperature fluidity, oxidation stability, and seal compatibility are also compared for four different ATFs. From the investigation, it was found that the use of Group III and IV base oils in ATFs gives several benefits with respect to low temperature viscosity, oxidation stability and SAE No.2 friction characteristics.

• 대한기계학회논문집A
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• 제35권10호
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• pp.1249-1255
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• 2011

공정열교환기는 초고온가스로로부터 생성된 $950^{\circ}C$ 정도의 초고온 열을 대량의 수소를 생산하기 위한 화학반응공정으로 전달하는데 필요한 핵심기기이다. Hastelloy-X 로 제작된 소형 공정열교환기 시제품이 한국원자력연구원에 있는 소형가스루프에서 성능시험이 계획되어 있다. 본 연구에서는 소형가스루프 시험조건하에서 소형 공정열교환기 시제품의 고온 구조건전성을 사전에 평가하기 위한 작업의 일환으로 소형 공정열교환기 시제품에 대한 고온 구조해석 모델링, 거시적 열 해석 및 탄 소성구조 해석을 수행하고 그 결과들을 정리한 것이다. 해석 결과는 공정열교환기 수정 시제품 성능시험장치 설계에 반영할 것이다.

• 한국구조물진단유지관리공학회 논문집
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• 제19권6호
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• pp.63-71
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• 2015

본 연구는 섬유를 혼입한 고강도 콘크리트의 온도 변화에 따른 내화특성 분석에 관한 연구로 고강도 콘크리트에 고온이 가해질 경우 발생되는 폭렬현상에 대하여 방지효과가 있는 것으로 알려져 있는 하이브리드섬유와 강섬유를 함께 혼입하여 만든 복합섬유를 사용하여 온도 변화($100{\sim}800^{\circ}C$)에 따른 고강도 콘크리트의 내화특성 및 역학적 메커니즘을 분석하였다. 또한 본 논문에서는 고강도 콘크리트 구조물에서 가장 문제가 되는 폭렬현상을 막는 대책 중의 하나인 섬유 혼입을 통한 방법을 사용하여 SEM 및 XRD 분석 등의 방법으로 고온을 받은 고강도 콘크리트의 열적 특성 및 역학적 특성을 규명하고자 하였다.

• 한국수소및신에너지학회논문집
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• 제19권3호
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• pp.232-238
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• 2008

Research has been proceeded on fuel cell which is fueled by hydrogen. Polymer electrolyte membrane fuel cell (PEMFC) is promising power source due to high power density, simple construction and operation at low temperature. But it has problems such as high cost, temperature dependent performance. These problems could be solved by experiment which is useful for analysis and optimization of fuel cell performance and heat management. In this paper, when hydrogen flows constantly at the stoichiometry of ${\xi}=1.6$, the performance of the fuel cell stack was increased and the voltage difference between each cells was decreased according to the increase of air stoichiometry by 2.0, 2.5, 3.0. Therefore, the control of air flow rate in the same gas channel is important to get higher performance. Purpose of this research is to expect operation temperature, flow rate, performance and mass transportation through experiment and to help actual manufacture of PEM fuel cell stack.

• 한국자동차공학회논문집
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• 제22권2호
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• pp.17-22
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• 2014

Recently, the quick heating performance is an important issue in the car because engine power becomes so high. So car makers have been adapted the additional heating devices as like PTC(Positive Temperature Coefficient) heater. And the quick cooling performance is also important issue because its result is used in the IQS(Initial Quality Study). In this paper, control of the HVAC(Heating, Ventilation and Air Conditioning) intake door has been studied for the quick heating and cooling performance. Heating performance is improved $4.0^{\circ}C$ at $-20^{\circ}C$ ambient temperature after 20 minutes. And cooling performance is improved $1.5^{\circ}C$ at $35^{\circ}C$ ambient temperature after 10 minutes. In addition, intake door control system brings on the cost reduction because the flab door can be eliminated. This intake door control system has been adapted to the new developing cars.