• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1238-1247
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• 2003

Simplified thermodynamic analysis of high pressure 4-stage reciprocating compressors with 4 inter-coolers has been investigated to predict a behavior of a compressor system for NGV(natural gas vehicles). A computer program has been developed to predict and estimate the performance of high pressure 4-stage reciprocating compressor system. Thermodynamic properties of compressed natural gas(CNG) were calculated by ideal gas theory and compression cycle was assumed as reversible adiabatic compression and expansion processes, and isobaric intake and discharge processes. Comparison between results predicted by calculation model and measured by experimental tests is presented.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.2
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• pp.84-91
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• 2006

A heavy duty hydrogen-natural gas fueled engine can obtain stable operation at ultra lean conditions and reduce emissions extremely. Reduction of $CO_2$ in its engine is one of the most benefit. In this study, rate of hydrogen addition($R_{dH2}$) and compression ratio($\varepsilon$) were investigated including performance of this engine. As results, it was found that phenomenon of pressure oscillation when increasing $R_{dH2}$ and $\varepsilon$, it means occurring knock. It consider that pressure oscillation was increased due to fast burning speed of hydrogen. Even if same compression ratio, pressure oscillation was remarkable increased according to increasing $R_{dH2}$. Therefore, limit compression ratio of knock occurring was reduced by increasing $R_{dH2}$.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.3
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• pp.90-96
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• 1995

In general, natural gas engine converted from gasoline engine has disadvantage of power decrease. In order to increase power output in natural gas engine, the improvement of in-cylinder flow motion has been believed as the most effective method. In this study, the geometry of combustion chamber in 4 valve DOHC natural gas engine is modified, and in-cylinder flow patterns is analyized. Also engine performance is evaluated according to the modification of in-cylinder flow motion.

• Journal of the Korean Professional Engineers Association
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• v.34 no.3
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• pp.28-32
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• 2001

Using the CNG(compressed natural gas) and LPG(liquified petroleum gas) as the automotive fuel will be expanded because of their clean effect to the environmental air qualify. But these programs of gas using expansion would have a difficulty due to public consideration of gas utilities as a big hazard. The Ministry of Environment has an ambitious plan to substitute more than 25,000 buses with CNG and ensure more than 200 CNG refueling stations as well by the year of 2007. However, it is very difficult to establish new CNG and LPG refueling stations because of expanded safety distance than ever before by several major explosion accidents.

• 한국신재생에너지학회:학술대회논문집
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• 2006.06a
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• pp.21-24
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• 2006

수소의 소규모 분산 생산 기술은 본격 적 인 수소 인프라가 도입되기 전에 연료전지 자동차의 수소 충전용이나 분산 발전형 연료전지의 수소 공급을 위해 필요하다. 생산 용량은 수소 기준으로 $20{\sim}100 Nm^3/hr$ 정도로 현재로선 천연가스의 수증기 개 질법이 가장 경제적인 공정으로 알려져 있다. 소규모 생산에 따른 열효율 저하를 줄이 기 위해 단위 공정들이 통합된 컴팩트 개질 시스템의 개발이 필요하다. 연료전지 자동차용 수소 인프라 조기 구축을 위하여 수소충전소 구축과 국산화 천연가스 수증기 개질기 개발을 병행하여 진행하였다. 수소 충전소 구축 부분은 충전소 부지 확보, 건물 건축, 각종 유틸리 티 설치의 토목 부분과 천연가스 개질형 수소 제조 유닛 설치, 수소 압축, 저장, 디스펜싱 시스템 설치를 포함하고 있으며 고압 설비에 대한 인허가 대응 및 안전대책 작업도 진행하였다. 구축된 수소충전소는 향후 연료전지 자동차 연계 실증 프로그램에 활용할 수 있다. 국산화 핵심 기술 개발을 위하여 열 및 시스템 통합 설계에 의 해 천연가스 수증기 개질기를 제작하고 내부 열교환 구조에 따른 개질기의 성능을 평가하였다. 개발된 개질기는 개질온도 $720^{\circ}C$, 수증기 대 카본 비 2.7의 운전조건에서 $23Nm^3/h$ 이상의 수소 생산이 가능하였으며 73% 이상의 개질 효율을 나타내었다. 개발된 천연가스 수증기 개질기는 향후 수소 정제용 PSA(Pressure Swing Adsorption) 시스템과 연계하여 수소충전소 국산화 엔지니어링 설계 패키지 개발의 핵심 기 술로 사용할 계획이다.시간 정도 운전한 후 시스템을 정지하였다 메탄 전환율과 일산화 탄소 농도, 열효율을 모니터링 하고 있으며, 현재까지 초기 성능을 그대로 유지하고 있다. 앞으로 일일시동-정지 운전 시험을 지속하면서 초기 시동 특성 및 부하 변동에 따른 응답 특성 개선, 그리고 연료전지와의 연계 운전을 실시할 예정이다 한다. 단위 전지 운전 온도 $130^{\circ}C$, 상대습도 37%의 운전 조건에서도 상당히 우수한 전지 성능을 보임에 따라 고온/저가습 조건에서 상용 Nafion 112 막보다 우수한 막 특성을 나타냄을 확인하였다.소/배후방사능비는 각각 $2.18{\pm}0.03,\;2.56{\pm}0.11,\;3.08{\pm}0.18,\;3.77{\pm}0.17,\;4.70{\pm}0.45$ 그리고 $5.59{\pm}0.40$이었고, $^{67}Ga$-citrate의 경우 2시간, 24시간, 48시간에 $3.06{\pm}0.84,\;4.12{\pm}0.54\;4.55{\pm}0.74 $이었다. 결론 : Transferrin에 $^{99m}Tc$을 이용한 방사성표지가 성공적으로 이루어졌고, $^{99m}Tc$-transferrin의 표지효율은 8시간까지 95% 이상의 안정된 방사성표지효율을 보였다. $^{99m}Tc$-transferrin을 이용한 감염영상을 성공적으로 얻을 수 있었으며, $^{67}Ga$-citrate 영상과 비교하여 더 빠른 시간 안에 우수한 영상을 얻을 수 있었다. 그러므로 $^{

• Applied Chemistry for Engineering
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• v.20 no.2
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• pp.117-125
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• 2009

In order to utilize natural gas (NG), one of the clean energy sources in next-generation, as a fuel for vehicles, it is important to store natural gas with high density. To store NG by adsorption (ANG) at room temperature and at relatively low pressure(35~40 atm) is safe and economical compared with compressed NG and liquefied NG. However, so far no adsorbent is reported to have adsorption capacity suitable for commercial applications. Nanoporous materials including metal-organic frameworks can be potential adsorbents for ANG. In this review, physicochemical properties of adsorbents necessary for high adsorption capacity are summarized. Wide surface area, large micropore volume, suitable pore size and high density are necessary for high energy density. Moreover, low adsorption-desorption energy, rapid adsorption-desorption kinetics and high delivery are needed. Recently, various efforts have been reported to utilize nanoporous materials in ANG, and it is expected to develop a nanoporous material suitable for ANG.

• Journal of the Korean Institute of Gas
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• v.17 no.6
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• pp.46-51
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• 2013

Composite cylinder is used by hydrogen fuel cell vehicles and natural gas vehicles because of high specific modulus, specific strength and fatigue resistance. composite cylinder has a seamless integrated liner and it is fully overwrapped with structural fibers of high strength carbon fibers in an epoxy matrix. In this study, filament winding pattern and autofrettage pressure design technique are presented considering structural weakness of knuckle and compressive residual stress. Presented methodology is verified by pressure cycling test of composite cylinders.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.1-6
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• 2003

Natural gas is one of the promising alternative fuels because of the abundant deposits and the cleanness of emission gas. CNG has a lot of merits except lower burning speed has a slow disadvantage. One way to overcome the disadvantage is to raise a turbulence intensity. We give various intake for changing turbulence intensity in the cylinder by three kinds of swirl control valve with a way to raise a turbulence intensity. In the present study, a $1.8\ell$ conventional gasoline engine is modified to use a CNG as a fuel instead of gasoline. We try to virify combustion and emission characteristics in each engine parameters. Parameters of experimentation are equivalence ratio, spark timing and intake flow change. The results of this study are as swirl flows. In the case of adding swirl flow, burning speed and torque are increased. But NOx and THC concentration are increased a little respectively.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.1
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• pp.7-17
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• 2003

Highly accurate control of an air-fuel ratio is very important to reduce exhaust gas emissions of gaseous-fuel engines. In order to achieve this purpose, a precise engine model is required to estimate engine performance from the engine design process which is applied to the design of an engine controller. Engine dynamics are considered to develop a dynamic engine model of a gaseous-fuel engine. An effective air mass ratio is proposed to study variations of the engine dynamics according to the water vapor and the gaseous-fuel in the mixture. The dynamic engine model is validated with the LPG engine under steady and transient operating conditions. The experimental results in the LPG gaseous-fuel engine show that the estimation of the air flow and the air-fuel ratio based upon the effective air mass ratio is more accurate than that of a normal engine model.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.4
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• pp.145-151
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• 2005

Natural gas is one of clean fuels that can replace petroleum-based fuels, because it has low exhaust emission, comparatively high thermal efficiency and abundant deposits. In this addition, owing to high octane number and wide lean flammability limit, it has a strong point to increase the compression ratio. For this reason, the research is being actively executed to increase the generating power and thermal efficiency of the engine by raising the compression ratio through utilization of high octane number relevant to development of CNG engine. In this study, 0.63L single cylinder diesel engine has been used to alter easily compression ratio. Compression ratio has gotten under control by modifying the thickness of gasket between cylinder head and block without major structural modifications. As the result, as compression ratio has increased, generating power and fuel consumption ratio have been improved. As for emission concentration, as compression ratio has increased, THC concentration has been decreased while exhause concentration of NOx increased. In case compression ratio has excessively increased, brake output decrease and cycle variation have been increased. As the result acquired by analyzing brake output, fuel consumption ratio, cycle variation and exhaust, the engine driving condition has acquired $\varepsilon=13$ as the optimal compression ratio in this study.