• Environmental and Resource Economics Review
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• v.2 no.2
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• pp.41-53
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• 1992

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.4
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• pp.387-394
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• 2013

Hydrogen-compressed natural gas (HCNG) blend has attracted attention as a fuel that can reduce $CO_2$ emissions because it has low carbon content and burns efficiently. An increase in the compression ratio of HCNG engines was considered as one of the methods to improve their efficiency and reduce $CO_2$ emissions. However, a high combustion rate and flame temperature cause abnormal combustion such as pre-ignition or knocks, which in turn can cause damage to the engine components and decrease the engine power. In this study, the performance and knock characteristics with a change in the compression ratio of an HCNG engine were analyzed. The combustion characteristics of HCNG fuel were evaluated as a function of the excess air ratio using a conventional CNG engine. The effects of the compression ratio on the engine performance were evaluated through the same experimental procedures.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.16-18
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• 2019

본 논문에서는 연료 전지 전기 자동차에 맞는 새로운 전력 변환 시스템을 제안한다. 연료 전지 전기 자동차의 전력 변환 시스템은 배터리와 같이 구성하여 에너지 저장 불가능, 느린 응답 속도, 낮은 전력 밀도와 같은 연료 전지의 단점을 해결할 수 있다. 하지만 기존의 연료 전지 전기 자동차의 전력 변환 시스템은 두 개의 DC/DC 컨버터를 사용하여 연료 전지와 배터리를 함께 구성함으로써 두 개의 인덕터 개수로 인해 비용이 증가하고 전력 밀도가 낮다는 단점이 있다. 제안하는 전력 변환 시스템은 한 개의 인덕터, 추가적인 스위치와 다이오드를 사용하여 연료 전지와 배터리를 하나의 컨버터로 구성한다. 따라서 기존에 비해 인덕터 개수가 감소함으로써 경제적이고 높은 전력 밀도 달성할 수 있으며, 스위치의 on/off 동작에 따라 승, 강압 동작이 가능하기 때문에 더 많은 연료전지와 배터리의 전압 조건 상황에서 동작할 수 있다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.65-67
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• 2019

본 논문에서는 연료 전지 전기 자동차에 맞는 새로운 전력 변환 시스템을 제안한다. 연료 전지 전기 자동차의 전력 변환 시스템은 배터리와 같이 구성하여 에너지 저장 불가능, 느린 응답 속도, 낮은 전력 밀도와 같은 연료 전지의 단점을 해결할 수 있다. 하지만 기존의 연료 전지 전기 자동차의 전력 변환 시스템은 두 개의 DC/DC 컨버터를 사용하여 연료 전지와 배터리를 함께 구성함으로써 두 개의 인덕터 개수로 인해 비용이 증가하고 전력 밀도가 낮다는 단점이 있다. 제안하는 전력 변환 시스템은 한 개의 인덕터, 추가적인 스위치와 다이오드를 사용하여 연료 전지와 배터리를 하나의 컨버터로 구성한다. 따라서 기존에 비해 인덕터 개수가 감소함으로써 경제적이고 높은 전력 밀도 달성할 수 있으며, 스위치의 on/off 동작에 따라 승, 강압 동작이 가능하기 때문에 더 많은 연료전지와 배터리의 전압조건 상황에서 동작할 수 있다.

• Journal of the Korean Applied Science and Technology
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• v.33 no.2
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• pp.264-270
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• 2016

This Study is to into fuel using a torrefation reaction to food waste. When the fuel of only food waste alone, fuel value is was performed at a ratio of sewage sludge constant attempts to prevent low. Mixing ratios of food waste and sewage sludge, 10:0, 8:2, 6:4, 5:5. Regardless mixing ratio, it was possible to confirm that decreases the moisture content of 10% or less at a reaction temperature of $240^{\circ}C$ or higher. As the ratio of the reaction temperature and the sewage sludge is high, the fixed carbon content is increased. It was measured at up to 36%(mixing ratios6:4, reaction temperature $270^{\circ}C$) from the initial 1.1%. From the reaction temperature $240^{\circ}C$ satisfied with 3000Kcal/Kg or more is a SRF criteria shows the calorific value. It was possible to obtain a heating value that is increased from the raw sample approximately sextuple. As reaction temperature is heightened, Van krevelen Diagram moved to the range of Lignite range. It was possible to obtain high fuel ratio and 5,500Kcal/kg or less of a combustility index as the sewage sludge mixing ratio becomes high. Increase the fixed carbon content, than those food waste alone solid fuel into and improved fuel costs, it is necessary to ensure that the quality of the fuel is improved.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.3
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• pp.22-29
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• 2004

Deformation of the porous media has influence on performance of a proton exchange membrane fuel cell (PEMFC). The stress distributions and deformation of the porous media are major factors for safe and efficient operation in the PEMFC. In this paper, nonlinear contact analysis of air plate and porous media is performed under a working condition to predict the performance characteristics of the air plates. Two kinds of models are suggested for this study. The first porous media model has nonlinear material properties. The second model has nonlinear material properties with contact condition between porous media and air plate. The numerical analysis results of the two models are somewhat different. It is shown that the nonlinear contact analysis is required for the design study of the PEMFC.

• Journal of the Korean Institute of Gas
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• v.15 no.5
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• pp.37-41
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• 2011

This paper presents the strength safety of a hydrogen gas composite fuel tank, which is analyzed using a FEM based on the criterion of US DOT-CFFC and Korean Standard. A hydrogen gas composite tank in which is fabricated by an aluminum liner of 6061-T6 material and carbon fiber wound composite layers of T800-24K is charged with a filling pressure of 70MPa and a gas storage capacity of 130 liter. The FEM results indicated that von Mises stress, 255.2MPa of an aluminum liner inner tank is low compared with that of 95% yield strength, 272MPa. And a carbon fiber stress ratio of a composite fuel tank is 3.11 in hoop direction and 3.04 in helical direction. These data indicate that a carbon fiber gas tank is safe in comparison to that of a recommended criterion of 2.4 stress ratio. Thus, the proposed composite tank with 130 liter capacity and 70MPa filling pressure is usable in strength safety.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.4
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• pp.80-87
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• 2004

To understand the each performance parameter correlation of flight type liquid-propellant rocket engine for KSR-III(Korea Sounding Rocket-III), the analysis of engine stand-alone combustion test results was carried out. Considering the variation of ablative material combustion chamber caused by erosion, linear regression analysis that ignores oxidizer/fuel ratio effect and two-variable 2nd-order polynomial regression analysis that considers oxidizer/fuel ratio change were performed. It can be described that linear regression analysis is simple and very practical method, and can predict the performance within 1% error inside analyzed region. And two-variable 2nd-order polynomial regression analysis can predict with very high accuracy inside region and shows that KSR-III engine's optimum oxidizer/fuel ratio for thrust(or specific impulse) is 2.22 and that for combustion chamber pressure(or characteristic velocity) is 2.17.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.75-84
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• 2018

In this study, the analysis of torrefaction products was carried out for fueling of sewage sludge. The mixed samples were composed as follows : 50% of sewage sludge and 50% of rice husk and CR(Coffee Residue). In this experiment, the reaction time(30min, 60min) and temperature($200^{\circ}C$, $250^{\circ}C$, $300^{\circ}C$) were expressed as a single variable using SF(Severity Factor). As a result, it was confirmed that as the SF increased, the heating value and fuel ratio increased, but the CI(Combustibility Index) decreased. The heating value was similarly increased as CR(Coffee Residue) and SF increased. The fuel ratio range of mixed samples was equal to that of lignite(0.5~1.0) in case of SF lower than 6.19 and that of bituminous coal(1.0~1.8) in case of SF higher than 7.36 or above. The CI showed a stable range(3,000~5,500kcal/kg) in low SF as the content of mixed samples contained more rice husk than CR.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.383-385
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• 2009

비백금계 코발트 전이금속 촉매를 탄소지지체에 담지한 뒤, 암모니아 분위기에서 $500^{\circ}C$에서 3시간 동안 열처리하는 과정을 통해 코발트 질화물 촉매를 제조했다. 제조된 촉매들의 구조와 형태를 각각 XRD, HE-TEM등을 통해 분석하였고, 전위 측정기를 이용한 CV, LSV 결과로부터 촉매의 전기화학적 산소 환원특성을 분석하여, 기존의 연료전지 양극 촉매로 사용되는 고가의 백금촉매를 대체하기 위한 비백금계로서의 가능성을 확인하였다.