• 오토저널
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• 제13권3호
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• pp.49-57
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• 1991

Natural gas is one of the most promising alternative fuels for automative vehicles, because it has lower exhaust emissions and better fuel economy characteristics than gasoline and can be used in conventional engines with a little modification. In the present study, a conventional gasoline engine was modified to a CNG dedicated engine, which can be operated with CNG( compressed natural gas) only, and a engine bench test was performed at various compression ratios. As a result, it was revealed that the prototype CNG engine can be operated with lower exhaust emissions, better fuel economy and better thermal efficiency, but with a sightly reduced brake horse power, compared to the conventional gasoline engine.

• 한국가스학회지
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• 제13권1호
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• pp.61-67
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• 2009

국내에는 가스를 사용하는 에너지 산업시설(저장시설, 고압가스 배관, 충전소, 탱크로리 등)이 전국에 산재해 있다. 이러한 대형 가스 시설에서는 화재, 폭발 및 유독물질 누출 등 중대사고가 발생할 수 있다. 또한 대기오염을 줄이기 위한 천연가스자동차의 보급으로 LNG(Liquefied Natural Gas), CNG(Compressed Natural Gas) 충전소의 보급이 늘어나고 있는 추세이다. 부천에서 발생한 LPG(Liquefied Petroleum Gas) 충전소의 대형가스사고 이후 충전소의 설치는 많은 어려움이 따른다. 따라서 이 연구에서는 LCNG/LNG 복합충전소를 연구대상으로 선정하고 기존의 정성적 위험성평가의 결과를 토대로 정량적인 위험성 평가를 표현하고, HSE(Health and Safety Executive) 기준과 비교를 통한 위험성을 확인하고자 한다.

• 한국분무공학회지
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• 제24권4호
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• pp.163-170
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• 2019

In this study, feedback logic using dual O₂ sensor values were developed to increase the purification capability of a three-way catalyst (TWC) in a compressed natural gas (CNG) engine. A heavy-duty inline 6-cylinder engine was used and the CNG was supplied to the engine through a mixer. This study consists of two main parts, namely, the proportional integral (PI) control with a front O₂ sensor and the feedback control with dual O₂ sensors. In the PI control experiment, effects of various parameters, such as P gain, I gain, and lean delay, on the TWC capability were identified. Based on the results of the PI control experiment, the feedback logic using dual O₂ sensor values were developed. In both cases, the nitrogen oxides (NO_X) emissions were nearly zero. However, the carbon monoxide (CO) emissions were reduced significant in the feedback logic with dual O₂ sensors than in the PI control with the front O₂ sensor.

• 한국분무공학회지
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• 제24권4호
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• pp.171-177
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• 2019

This paper describes numerical study of combustion characteristics in CNG(compressed natural gas) DI(direct injection) engine using gaseous sphere injection model. Simulations were conducted using KIVA-3V Release 2 code. Gaseous sphere injection model, which is modified model of liquid fuel injection, was used to simulate the CNG direct injection. Until now, a very fine mesh smaller than the injector nozzle has been required to resolve the gas-jet inflow boundary. However, the gaseous sphere injection model simulates gaseous fuel injection using a coarse mesh. This model injects gaseous spheres as in liquid fuel injection and the gaseous spheres evaporate together without the latent heat of evaporation. Therefore, it does not require a very fine mesh and reduce calculation time. Combustion simulation were performed under various injection timings and injection pressures.

• 대한기계학회논문집A
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• 제35권4호
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• pp.439-445
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• 2011

대기오염 등 환경에 대한 관심이 높아지면서 경유차 배출 가스 저감을 위한 최적의 대안으로 최근 세계적으로 천연가스차량의 보급이 크게 확대되고 있는 추세이다. 이러한 추세에도 불구하고 그 안전성에 대해서는 많은 논란을 불러 일으키고 있으며 최근 그 이용에 따른 안전사고 또한 빈번하게 발생하고 있다. 천연가스버스 압력용기 파열 사고는 대중들이 많이 이용한다는 점에서 대형참사로 이어질 수 있는 잠재력을 가지고 있어 그 심각성은 매우 크다고 할 수 있다. 이에 법공학적인 측면에서 좀 더 전문화되고 체계적인 사고조사와 원인 규명을 통해서 사전에 예방대책을 마련함으로써 유사 및 동종재해의 발생을 최소화해야 한다. 본 연구에서는 구조해석을 통한 용기의 설계 검증과 용기의 파손형태 검사 및 재료 물성평가 등을 통해 용기파손에 의한 CNG 차량 폭발 사고에 관한 정확한 사고 원인을 규명함으로써 동일 형태의 차량 안전사고 예방에 기여하고자 한다.

• Tribology and Lubricants
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• 제22권6호
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• pp.329-334
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• 2006

In CNG (Compressed natural gas) fuel supply line, whose main components are receptacle and check valve are used to charge high pressure gas to the tank of NGV (Natural gas vehicle). It is reported that the seal is separated occasionally form valve seat and results in blockage of gas flow. In this paper, MARC is used to investigate the reasons of seal separation and suggest design improvements. The static gas pressure distributions acting on the seal which calculated using FLUENT are considered to investigate accurate seal deformation behaviors. Deformed seal shapes are obtained for various amounts of seal interference and its location, gas pressure distributions and Young's modulus of the rubber used. The results showed that the reasons of seal separation problems are verified theoretically, and suggested examples of new design method. Therefore the present numerical methods can be applied in designing and performance analysis of rubber seals adopted in high pressure fluid machineries.

• 한국가스학회지
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• 제15권1호
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• pp.9-14
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• 2011

대형 디젤엔진은 주행거리가 길고 배기량이 크기 때문에 차량의 대수는 상대적으로 적지만 대기환경에 미치는 영향은 크다. 시내를 주행하는 시내버스의 경우 한일 월드컵을 계기로 CNG 버스로 전환되었다. 그러나 대형트럭과 장거리 시외버스의 경우 주행거리가 길고 CNG 충전소가 대도시의 시내버스 차고지 위주로 설치되어 있어 이용이 불가능하였다. 단열용기의 적용으로 천연가스를 압축상태가 아닌 액체 상태로 보관이 가능해져 주행거리가 긴 대형트럭이나 장거리 시외버스로의 적용이 가능해졌으며, 혼소엔진의 경우 LNG 충전이 어려운 지역에서는 디젤로 운행이 가능하다. 이와 같은 장점으로 인하여 석유 의존도를 크게 낮출 수 있어 에너지원의 다변화가 가능하며, 디젤차의 고질적인 단점으로 여겨왔던 매연 및 질소산화물뿐만 아니라 저탄소 연료를 사용함으로서 대표적인 온실가스중의 하나인 이산화탄소도 10%이상 저감할 수 있었다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.557-561
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• 2005

In recent years, the LNGC fleet is expanded unprecedentedly. Ship's owners and shipbuilders are focusing on the idea how they choose the BOG handling system in economical, environmental and safety angles. This paper introduces general information for that and gives technical matters briefly.

• 한국해양공학회지
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• 제27권1호
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• pp.51-58
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• 2013

Recently, there has been an increase in the demand for natural gas as a source of clean energy, which has increased the demand for LNG carriers. However, LNG carriers require a capital investment to obtain equipment for the regasification process, which prevents fires and explosions. Thus, on account of NIMBY, a CNG carrier is suggested that eliminates the need for regasification equipment. Meanwhile, carbon dioxide emissions are more and more regulated by international conventions such as the Kyoto Protocol. Because of this, $CO_2$ carriers have also received international attention as a methodology to transport and store $CO_2$ cargoes. Several vessels or tanks to transport and store $CO_2$ gas have been studied in various countries. This paper proposes a conceptual design for a 20ft container shaped tank to effectively transport small cargoes of $CO_2$ and CNG. The proposed pressure vessel or tank will be carried by a conventional containership or special cargo ship. The influences of the design parameters for proposed pressure vessel or tank. Including the materials, scantlings, and shape of the pressure vessel, are studied theoretically and computationally.

• 동력기계공학회지
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• 제22권6호
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• pp.74-79
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• 2018

Compressed natural gas has a high octane number and low particulate emission characteristics as compared with petroleum-based fuels, so it can respond to exhaust gas regulations positively. A natural gas engine has been introduced to improve the quality of the atmosphere, a diversity of fuel, a stable supply, and it has widely been used in city buses and garbage trucks. Recently, the natural gas engine has received attention by overcoming the disadvantage of the theoretical air-fuel ratio method through the development of EGR cooler and engine parts with the development of LP-EGR technology. In this study, we try to develop the cogeneration system that can simultaneously generate electric power and heat by remodeling the gasoline engine to the mixer type CNG engine. As a result, it was able to reduce the NOx (approximately 77%) compared to the diesel engines with same displacement.