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흡기포트 DME 저압분사가 커먼레일 경유 직분엔진의 성능 및 배출가스 특성에 미치는 영향
이준혁(Junhyuk Lee),표영덕(Youngdug Pyo),강우(Woo Kang),이영재(Youngjae Lee) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Dimethyl ether (DME) is an oxygenated fuel with a cetane number higher than that of diesel oil, and it realizes smoke free combustion. In the present study, effects of DME intake port injection on the performance and exhaust emissions of common rail direct injection engine using diesel oil were investigated, Test results showed that specific energy consumption of this duel fuel operation was the same as that of diesel oil only, but smoke emission was considerably reduced with the increase of DME injection ratio.
디젤 파일럿 압축착화 천연가스엔진의 성능 및 배출가스 특성
이준혁(Junhyuk Lee),표영덕(Youngdug Pyo),권오석(Ohseuk Kwon),이용균(Yonggyun Lee),나평철(Pyungchul Na),류정인(Jeongin Ryu),이영재(Youngjae Lee) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Natural gas has superior characteristics that are low fuel efficiency, low CO₂, low pollution and stabilization. And it is possible to apply to existing diesel engine with some mechanical modification. Diesel pilot compression ignition CNG engine has advantage of power and efficiency as same as diesel engine without high cost of remodeling and it can use advantage of high compression ratio of diesel engine and has low Smoke and NOx. In the present study, an existing diesel engine was remodeled into single cylinder Diesel pilot CNG engine has two fuel suppling system, one is diesel pilot injection in cylinder using existing Electronic Unit Injector(EUI), the other is the way that injected CNG into a intake manifold using instituted supply apparatus. The test results showed that diesel pilot injection timing was decided 13°BTCD and diesel pilot injection fuel flow was decided 0.19 L/h. At that condition, Smoke and CO were reduced and NOx was slightly increased than using diesel fuel.
Zero Common-Mode PWM 기법의 DC-링크 커패시터 전류 감소 효과
이준혁(Junhyuk Lee),장유남(Yu-Nam Jang),김명원(Myeong-Won Kim),박정욱(Jung-Wook Park) 전력전자학회 2021 전력전자학술대회 논문집 Vol.2021 No.7
본 논문에서는 인버터의 병렬 운전을 위한 펄스폭 변조(Pulse-width modulation, PWM) 기법의 하나인 Zero common-mode(Zero-CM) PWM 기법의 DC-링크 커패시터 전류 감소효과에 대해 분석하였다. DC-링크 커패시터 전류는 DC-링크 커패시터의 수명, 크기, 가격 등에 직접적인 영향을 미치므로, DC-링크 커패시터 전류를 줄이는 것은 인버터 시스템에 큰 이익이 된다. Zero-CM PWM 기법은 이웃한 유효 전압 벡터 또는 서로 다른 영 전압 벡터를 동시에 사용함으로써 병렬 인버터의 공통모드 전압을 이론적으로 완전히 제거하는데, 이는 DC-링크 커패시터 전류 또한 감소시키는 효과가 있다. Zero-CM PWM 기법에 따른 DC-링크 커패시터 전류 감소 효과는 PSIM 시뮬레이션을 통해 검증되었다.
강체인 구와 DLC 코팅면 사이의 압입 및 미끄럼 접촉해석
이준혁(JunHyuk Lee),박태조(TaeJo Park) 한국트라이볼로지학회 2014 한국윤활학회지(윤활학회지) Vol.30 No.4
Various heat-treated and surface coating methods are used to mitigate abrasion in sliding machine parts. The most cost effective of these methods involves hard coatings such as diamond-like carbon (DLC). DLC has various advantages, including a high level of hardness, low coefficient of friction, and low wear rate. In practice, a supporting layer is generally inserted between the DLC layer and the steel substrate to improve the load carrying capacity. In this study, an indentation and sliding contact problem involving a small, hard, spherical particle and a DLC-coated steel surface is modeled and analyzed using a nonlinear finite element code, MARC, to investigate the influence of the supporting layer thickness on the coating characteristics and the related coating failure mechanisms. The results show that the amount of plastic deformation and the maximum principal stress decrease with an increase in the supporting layer thickness. However, the probability of the high tensile stress within the coating layer causing a crack is greatly increased. Therefore, in the case of DLC coating with a supporting layer, fatigue wear can be another important cause of coating layer failure, together with the generally well-known abrasive wear.