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최관희,이형민,황인구,Cha-Lee Myung,박심수 대한기계학회 2008 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.22 No.11
In a gasoline SI engine, valve events and spark timings put forth a major influence on overall efficiency, fuel economy, and exhaust emissions. Residual gases controlled by the valve overlap can be used to reduce NOx emissions and the spark retardation technique can be used to improve raw THC emissions and catalyst light-off performance during the cold start phase. This paper investigated the behaviors of the engine and its combustion characteristics with various intake valve timings and spark timings during the fast idle condition and cold start. And cyclic THC and NOx emissions were measured at the exhaust port and their formation mechanisms were examined with fast response gas analyzers. As a result, THCs and NOx were reduced by 35% and 23% with optimizing valve overlap and spark advance during the cold transient start phase. Consequently, the valve events and ignition timings were found to significantly affect combustion phenomena and cold-start emissions.
과급 GDI 차량의 Mode 주행 시 극미세입자 배출 특성에 관한 연구
최관희(Kwanhee Choi),고아현(Ahyun Ko),황인구(In Goo Hwang),명차리(Cha-Lee Myung),권상일(Sangil Kwon),박심수(Simsoo Park) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
GDI engines have widely adopting recently for advantages in engine performance and fuel economy compared with conventional MPI gasoline engines, but disadvantages in particulate matter, not only its mass but also its number, have becoming a problem. This paper investigated about nano-particle characteristics exhausted from a turbo-charged gasoline direct injection vehicle during regulated vehicle driving cycle. As a result, particulate matters mainly exhausted during cold condition and rapid acceleration. The total particle number concentration of the GDI vehicle on NEDC mode was measured as 6.03E+11 N/㎞, which cannot satisfy the expecting particle number regulation, 6.0E+11 N/㎞, scheduled to start in Euro-6 emission regulation. Size distribution of particulate matters assessed by the fast response PM analyzer showed that accumulation mode particles near 60㎚ mainly exhausted, nuclei mode particles under 30nm appeared simultaneously. Therefore, efforts to reduce the particle number emission of the GDI engine should be achieved by reforming the engine body as well as improving the EMS logic.
조기영,최관희,유갑용 동아대학교 건설기술연구소 1997 硏究報告 Vol.21 No.2
Prediction of consolidation settlement and time must be always erroneous because of soil media, errors associated with the measurement of soil parameters, drawback of consolidation theories and so on. When Oiling on compressible soils, the observational method is a useful means in pratice to evaluate the final consolidation settlement and time. However, the ousted observational procedures include some disadvantages which are difficulty of finding the linearity in the settlement curves, which a personal error seems to be unavoidable and so on. A new observational procedure(√s method) is suggested here to perform the consolidation analysis in field. As the results of applying the √s method with another methods to two field data, the final settlement predicted by the √s method as well as by the Asaoka's method agreed well with the measured value. However, one by the hyperbolic method(Tan, 1991) was overestimated, and there happened many cases not to predicted by the Hoshino's method. In the settlement curve from the √s method, the linearity between 60 and 90% of the average degree of consolidation is showed, and then the possibility of happening a personal error seems to be unusual. The final consolidation time(at 0.95s_(f)) predicted by the √s method agreed well with the measured one, but one by Asaoka and Tan(1996) methods was very much underestimated or overestimated. The big errors by the two methods seem to be the cause unconsidered the effect of step loading.
GDI 엔진의 연료 분사 제어 로직에 따른 나노입자 배출 특성에 관한 연구
이효근(Hyokeun Lee),최관희(Kwanhee Choi),명차리(Cha-Lee Myung),박심수(Simsoo Park),박종일(Jongil Park),한승국(Seung Kook Han) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
Nano-particle characteristics were investigated in the gasoline direct injection engine, for various air fuel ratios, fuel pressures and fuel injection timings in the part load condition. PN concentration and size distribution were measured by the DMS-500 equipped upstream of catalyst. Nano particle emission was closely related with fuel injection timing and in-cylinder flow motion in GDI engine. As a result, PN was decreased with increasing air fuel ratio and fuel pressure. And fuel injection timing was retarded over the middle intake stroke, particle emission was increased but reduced PN during the early intake stroke. In conclusion, optimization of the ECU control strategy on the fuel injection pressure, injection timing as well as air fuel ratio was needed to improve the nano particle emissions in GDI engine.
포트 마스킹과 흡기 밸브 타이밍이 실린더 내부의 싸이클별 HC와 NOx 생성에 미치는 영향
전우주(Wooju Jeon),최관희(Kwanhee Choi),명차리(Cha-Lee Myung),박심수(Simsoo Park),이경환(Kyung-Hwan Lee) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
This paper investigated the behaviors of combustion characteristics at part load condition with various intake charge motions induced by the port masking schemes in the CVVT (Continuously Variable valve Timing) engine. Time resolved in-cylinder and exhaust emissions were measured by the fast response HC and NOx analyzers to examine their formation mechanisms and behavior characteristics. As a result, in-cylinder HC decreased with the advanced intake valve timings but HC at the exhaust port increased due to the worse combustion stabilities. However HC reduction could be achieved by the application of the port maskings with a enhancement of the engine stability. NOx also decreased with early intake timings by internal EGR but increased with the charge motion controls which enhance the combustion behavior.
SI 엔진의 시동 및 아이들 구간에서의 점화시기에 따른 싸이클별 연소현상에 관한 실험적 연구
최성원(Seongwon Choi),최관희(Kwanhee Choi),명차리(Cha-Lee Myung),박심수(Simsoo Park) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.5
THC(Total Hydrocarbon) emissions during cold start and warm-up phase constitute the majority of THC emissions during the FTP-75 mode. As the basic approach to improve the emission performance of Gasoline engine during transient phase, the effect of spark timing retard from MBT on THC emission characteristics is studied by engine test using a Fast response Flame Ionization Detector(FFID). A cyclic analysis of the combustion process shows that high THC emissions are produced first few cycles during the transient phase. This paper presents the results of engine performance and emission of Gasoline engine with various spark timing consequently, This paper was focused on the combustion phenomena with various spark timing during transient phase which was analyzed by Fast response Flame Ionization Detector(FFID) equipment to measure the cyclic THC emission characteristics.