• 오토저널
• /
• 제7권4호
• /
• pp.24-31
• /
• 1985

본 논문은 Comprex압력파 과급기(Pressure-wave Supercharger;이하 PWS)의 공기 역학적인 원 리에 대해 기술하였으며, 또 기체 동력학적인 현상들이 별도의 제어장치없이도 우수한 운전성과 낮은 연료소모율, 적은 배기 배출물을 형성하는 차량들에 대해 기계적으로는 간단하면서도 완벽 한 boosting장치를 만들어 내는데 어떻게 사용될 수 있는지를 설명하였다. 근본적인 목적은 종 래의 turbo charger와 동일이지만 Comprex PWS는 현재 응용되고 있는 승용차가 요구하는 여러 가지면, 즉 1) 부하변동에 대한 충진공기압의 빠른 응답성 2) 엔진속도 전영역에 걸친 높은 boost 효과 3) 배기배출물특성을 좋게할 수 있는 배기가스 재순환(EGR)효과 등에서 종래의 것과 구별된다. 따라서 PWS의 중요한 특징들을 기술하였으며 마지막으로 최근 자동차용 Diesel Engine에의 몇 가지 예를 보았다.

• 한국자동차공학회논문집
• /
• 제6권2호
• /
• pp.32-42
• /
• 1998

Lean burn gasoline engine is recognized as a promising way to meet better fuel economy. Lean burn engine is classified into port injection and direct injection(DI), DI is more active technique for improving fuel economy with ultra-lean operation, Nowadays, port injected lean burn engine has been produced by many Japan maker. Also, DI engine is also possible for production owing to improvement in control technique of spray, flow air fuel ratio. DI engine uses either homogeneous stoichiometric mixture or stratified mixture by controlling injection timing to be early or late respectively. HM(homogeneous mixture) is worse than SM(stratified mixture) in view of ultra-lean operation in partical load and Nox reducion by using EGR control. But, HM has advanteges in cold starting and emission reduction during transient operation, This paper describes experimental variables and bench test results of HM GDI engine.

• 한국대기환경학회:학술대회논문집
• /
• 한국대기환경학회 2003년도 추계학술대회 논문집
• /
• pp.181-182
• /
• 2003

경유엔진은 가솔린엔진에 비해 연소특성상 연료소비효율이 우수하여 온실가스인 $CO_2$ 배출이 적은 반면 대기 및 인체위해성이 높은 NOx와 입자상물질(PM)의 배출이 많아 대기저감을 위한 연료의 고압분사, 전자제어식 EGR기술등 엔진개량기술과 매연여과장치, De-NOx등 후처리기술 그리고 대체연료사용 기술등 다양한 저감대책이 전세계적으로 강구되고 있다. 특히 경유엔진에서 배출되는 오염물질로 인한 대기오염영향은 점차 증가하고 있어 대체연료사용 및 배출허용기준강화둥 우리 실정에 적합한 효율적인 대기저감대책이 강구되어야 할 것이다. (중략)

• 기계저널
• /
• 제23권6호
• /
• pp.427-433
• /
• 1983

내연기관의 성능은 실린더에서 연료의 화학에너지가 열에너지로 얼마만큼 빠르고 완전하게 변화하느냐에 좌우된다. 이를 위해서는 실린더 내에서 뜨거운 압축공기와 연료의 혼합 및 증기화가 요구된다. 엔진의 출력은 매 사이클당 흡입.압축할 수 있는 공기량에 좌우되므로 연소의 해석을 위해서는 실린더 내의 공기유동, 연료의 분무 및 연소과정을 이해 해야한다. 배기와 엔진효율의 요구성때문에 희박 혼합기 또는 EGR (exhaust gas recirculation)이 필요하게 된다. 그러나 희석이 크면 낮은 연소온도, 낮은 층류흐름속도와 화염전면의 낮은 난류강도 때문에 연소기간이 증대하게 된다. 실제로 희박의 증가는 실화 또는 긴 연소 지연기간, 사이클 마다의 연소맥동현상, HC배기의 증가등을 초래하게 된다. 이러한 저온연소의 단점들은 연소상태를 안정시키고 연소량을 증대시키는 공기의 유동을 이용해서 해결 될 수 있다. 최근에는 선회류와 난류의 강도를 증가시켜서 빠른연소(fast burning)를 이루고 있다. 선회류와 난류의 강도를 증대시키는 가장 중요한 2가지 방법은 흡입포트(port), 매니홀드(manifold)설계이다.

• 한국자동차공학회논문집
• /
• 제10권2호
• /
• pp.80-86
• /
• 2002

A fuel injection system has an important role in the performance and emission gas in a diesel engine. In this paper, an experimental study has been performed to verify the effect of the performance and the emission gas with the factors such as diameters of an injection nozzle hole, diameters of an injection pipe, and injection timing in the fuel injection system. We have obtained the results that the fuel consumption ratio is reduced and NOx concentration is increased as the smaller diameter of injection nozz1e hole, the smaller diameter of injection pipe, and more advanced injection timing. They show that optimizing the factors of fuel injection system is significant to enhance the performance of the engine system and consumption ratio of fuel, smoke, and NOx.

• 한국자동차공학회논문집
• /
• 제13권2호
• /
• pp.101-107
• /
• 2005

In this paper, optimized operating parameters were found using multi-dimensional engine simulation software (KIVA-3V) and micro-genetic algorithm for heavy duty diesel engine. The engine operating condition considered was at 1,737 rev/min and 57 % load. Engine simulation model was validated using an engine equipped with a high pressure electronic unit injector (HEUI) system. Three important parameters were used for the optimization - boost pressure, EGR rate and start of injection timing. Numerical optimization identified HCCI-like combustion characteristics showing significant improvements for the soot and $NO_X$ emissions. The optimized soot and $NO_X$ emissions were reduced to 0.005 g/kW-hr and 1.33 g/kW-hr, respectively. Moreover, the optimum results met EPA 2007 mandates at the operating point considered.

• 한국연소학회지
• /
• 제16권2호
• /
• pp.9-15
• /
• 2011

Homogeneous charge compression ignition(HCCI) is the best concept able to provide low NOx and PM in diesel engine emissions. This new alternative combustion process is mainly controlled by chemical kinetics in comparison with the conventional combustion in internal combustion engine. In this paper, combustion characteristics of HCCI engine with suggested diesel surrogate(heptane/toluene mixture fuel) reaction mechanism were numerically investigated by heptane/toluene mixture ratio and EGR ratio. As results, the ignition timing became faster with increasing of heptane, and an initial oxidation and the ignition timing of the mixture fuel were affected by heptane and toluene, respectively.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.3079-3084
• /
• 2008

A fast response $CO_2$ analyzer has been developed for measuring the $CO_2$ concentration during transient condition of SI engine. The analyzer is based on the non-dispersive infrared absorption technique, electrical chopping system and water cooling system. The analyzer has good repeatability, linearity and permissible drift characteristic. Besides, it has 18ms with a response to measure the $CO_2$ concentration. The fast response $CO_2$ analyzer was applied to single cylinder SI engine and the $CO_2$ emission was examined during engine start. Simultaneously, the standard exhaust gas analyzer, which has slow response time, was used for considering the engine-out $CO_2$ characteristic. The developed analyzer showed much faster responsive characteristic than that of a standard analyzer and made cycle by cycle exhaust gas analysis possible. The transient engine operating characteristics will be estimated and the transient behaviors on engine-out emission and performance will be improved.

• The Korean Journal of Physiology and Pharmacology
• /
• 제4권5호
• /
• pp.355-359
• /
• 2000

Cocaine induces immediate early gene expression and behavioral changes by blocking dopamine transporters in the terminals of nigrostriatal neurons in the striatum. The pharmacological role of serotonin 2/1C (5HT2/1C) receptors in cocaine-induced expression of zif268 (NGFI-A, egr1 and Krox-24) mRNA, a member of the zinc finger, was investigated using quantitative in situ hybridization histochemistry in vivo. Behavioral alterations induced by cocaine were also monitored in relation with blockade of the receptors. Systemic injection of ritanserin (1 mg/kg, s.c.), a 5HT2/1C receptor antagonist, did not reverse behavioral alterations and zif268 mRNA gene expression induced by 15 mg/kg cocaine, i.p., in the dorsal and ventral striatum. These data indicate that ritanserin-sensitive 5HT2/1C receptors are not necessary for cocaine-induced behavioral alterations and zif268 mRNA gene expression in the striatum.

• 대한기계학회논문집B
• /
• 제31권6호
• /
• pp.514-521
• /
• 2007

This study focused on the effects of the $CO_2$ gas concentration in fresh charge and induction air temperature on the combustion characteristics of homogeneous charge compression ignition with dimethyl ether (DME) fuel, which was injected at the intake port. Because of adding $CO_2$ in fresh charge, start of auto-ignition was retarded and bum duration became longer. Indicated combustion efficiency and exhaust gas emission were found to be worse due to the incomplete combustion. Partial burn was observed at the high concentration of $CO_2$ in fresh charge with low temperature of induction air. However, indicated thermal efficiency was improved due to increased expansion work by late ignition and prolonged bum duration. Start of auto-ignition timing was advanced with negligible change of burn duration, as induction air temperature increased. Burn duration was mainly affected by oxygen mole concentration in induction mixture. Bum duration was increased, as oxygen mole concentration was decreased.