http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
레이저 굴절법을 이용한 LPG와 가솔린 연료의 화염전파 특성에 관한 연구
이기형,이창식,강건용,강우,Lee, Kihyung,Lee, Changsik,Kang, Kernyong,Kang, Woo 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.12
For the purpose of obtaining fundamental data which is needed to develope combustion system of LPG engine, we made constant volume chamber and analyzed flame propagation characteristics under different intial temperature, initial pressure and equivalence ratio which affect combustion of LPG. We investigated flame propagation speed of each fuel using laser deflection method and compared with the investigated flame propagation speed of each fuel using laser deflection method and compared with the results of image processing of flame. As a result, the maximum flame propagation speed was found at equivalence ratio 1.0 and 1.1 for LPG and gasoline, respectively. In the lean region, we can see that flame propagation speed of LPG surpasses that of gasoline. On the contrary, flame propagation speed of gasoline surpasses LPG in the rich region. As initial temperature and initial pressure were higher, flame propagation speed was faster. And, as equivalence ratio was larger and initial temperature was higher, combustion duration was shorter and maximum combustion pressure was higher.
정적 연소실내 혼합기 분포와 연소특성에 미치는 영향에 관한 실험적 연구
이기형(Kihyung Lee),이창희(Changhee Lee),안용흠(Yonghun An) 한국자동차공학회 2004 한국 자동차공학회논문집 Vol.12 No.3
It is well known that the stratified charge combustion has many kind of advantages to combustion characteristics, such as higher thermal efficiency and Iess CO, NOx levels than conventional homogeneous mixture combustion. Although this combustion can be caused low fuel consumption, it is produced the high unburned hydrocarbon and soot levels because of different equivalence ratio in the combustion chamber. Moreover it has a lot of possibility of low output and misfire if the mixture gas would not be in existence around the spark plug. In this paper, fundamental studies for stratified combustion were carried out using a constant volume combustion chamber. The effect oflocally mixture gas distribution according to control the direct injection and premixed injection in the chamber were examined experimentally. In addition, the eflects of turbulence on stratified charge combustion process were observed by schlieren photography.
이기형(Kihyung Lee),김용래(Yonglae Kim),배재일(Jaeil Bae) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Recently, the international regulations about the exhaust emission of the motorcycle have been strengthened. In case of the motorcycle engines, the quantity of the exhaust emission is larger than that of the car because of the carburetor type fuel supply system, which can not control the A/F precisely. Therefore, the electrically controlled fuel injection type motorcycle has been emphasized to meet with this regulation. However, since the pulsation phenomenon happens in the intake port of the motorcycle because of the characteristic of high speed and the smaller layout than the passenger car driving condition, there are many difficulties to select the factor about control parameters needed to develop the ECU system. For addition, an air flow rate is the important basis parameter at the ECU system. In this paper, the pulsation values measured from the engine test were compared with the calculated value by WAVE, and we analyzed the intake pressure characteristic according to the driving condition. Finally, an air flow rate is estimated by simulation method.
이기형(KiHyung Lee),반재훈(ChaeHoon Ban),김동현(DongHyun Kim),홍봉희(BongHee Hong) 한국정보과학회 2004 한국정보과학회 학술발표논문집 Vol.31 No.2Ⅱ
최근 유비쿼터스 환경에서 객체에 태그를 장착하여 위치를 추적하는 응용분야가 늘어가고 있는 추세이며, 이러한 응용에서 빈번히 사용되는 질의는 객체의 위치를 찾는 find와 특정 위치의 객체를 찾는 look 질의가 있다. 이 두 질의에서 처리되는 데이터는 시간과 공간을 포함한 다차원 대용량 데이터이며 과거 및 현재 상태의 검색을 지원해야 하므로 효율적인 질의 처리를 위해서는 태그 객체를 위한 새로운 데이터 모델과 색인이 필요하다. 본 논문에서는 태그 객체를 간격 데이터로 정의하고 과거 및 현재 데이터에서 find와 look 질의를 처리할 수 있는 색인 구조를 제안한다. 제안하는 색인에서 노드에 오버플로우가 발생할 경우 새로운 단말 노드 분할 정책을 사용하여 분할하며 성능 평가를 통해서 기존 정책보다 우수함을 증명한다.
직접분사식 소형 디젤엔진의 실린더내 스월 유동장에 미치는 흡기포트의 형상에 관한 연구
이기형(Kihyung Lee),한용택(Yongtaek Han),정해영(Haeyoung Jeong),임영철(Youngchul Leem) 한국자동차공학회 2004 한국 자동차공학회논문집 Vol.12 No.6
This paper studies the effects of intake port configuration on the swirl that is key parameter in the flow field of direct injection diesel engines. In-cylinder flow characteristics is known to have significant effects on fuel air mixing, combustion and emissions. To investigate the swirl flow generated by various intake ports, steady state flow tests were conducted to evaluate the swirl. Helical port geometry, SCV shape and bypass were selected as the design parameters to increase the swirl flow and parametric study was performed to choose the optimal port shape that would generate a high swirl ratio efficiently. The results revealed that a key factor in generating a high swirl ratio was to suitably control the direction of the intake air flow passing through the valve seat. For these purposes, we changed the distance of helical and tangential port as well as installed bypass near the valve seat and the effects of intake port geometry on in-cylinder flow field were visualized by a laser sheet visualization method. From the experimental results, we found that the swirl ratio and mass flow rate had a trade off relation. In addition, the result indicates that the bypass is a effective method to increase the swirl ratio without sacrificing mass flow rate.
연로조성에 따른 HCCI 엔진의 냉염 및 열염의 2단연소 특성에 관한 실험적 연구
이기형(Kihyung Lee),김형민(Hyungmin Kim),류재덕(Jeaduk Ryu),이창식(Changsik Lee) 한국자동차공학회 2004 한국 자동차공학회논문집 Vol.12 No.1
As the environmental pollution becomes serious global problem, the regulation of emission exhausted from automobiles is strengthened. Therefore, it is very important to know how to reduce the NOx and PM simultaneously in diesel engines, which has lot of merits such as high thermal efficiency, low fuel consumption and durability. By this reason, the new concept called as Homogeneous Charge Compression Ignition(HCCI) engines are spotlighted because this concept reduced NOx and P.M. simultaneously. However. it is well known that HCCI engines increased HC and CO. Thus, the investigation of combustion characteristics which consists cool and hot flames for HCCI engines were needed to obtain the optimal combustion condition.<br/> In this study, combustion characteristics for direct injection type HCCI engine such as quantity of cool flame and hot flame, ignition timing and ignition delay were investigated to clarify the effects of these parameters on performance.<br/> The results revealed that diesel combustion showed the two-stage ignition of cool flame and hot flame, the rate of cool flame increase and hot flame decrease with increasing intake air temperature. On the other hand, the gasoline combustion is the single-stage ignition and ignition timing is near the TDC. In addition mixed fuel combustion showed different phenomenon, which depends on the ratio of gasoline component. Ignition timing of mixed fuel is retarded near the TDC and the ignition delay is increased according to ratio of gasoline.<br/>
직분식 예혼합 압축착화 디젤엔진의 운전조건과 연료조성에 따른 연소 및 배기 특성
이기형(Kihyung Lee),류재덕(Jeaduk Ryu),이창식(Changsik Lee) 한국자동차공학회 2004 한국 자동차공학회논문집 Vol.12 No.1
The Homogeneous Charge Compression Ignition (HCCI) engine has advantage for reducing the NOx and P.M. simultaneously. Therefore, HCCI engine is receiving attention as a low emission diesel engine concept.<br/> This study was carried out to investigate the characteristics of combustion and exhaust emission for operating conditions in a direct injection type of HCCI engines such as supercharged and naturally aspirated using diesel fuel and additive. From the experimental resull, we found that cool flame was always appeared and also it was difficult to control combustion characteristics by changing the injection timing in HCCI. In addition, at the lean air-fuel ratio and high speed range, it was observed that charging air pressure, additive or increasing intake air temperature is effective to increase combustion performance and reduce exhaust emission. We concluded that chemical reaction by the increasing intake air temperature or additive without physical improvement has limitation for reduction of exhaust emission.<br/>