강제 변위 제어와 곡면 비교를 고려한 선체 외판 열간 곡가공 정보의 정밀화

학위논문(박사) --서울대학교 대학원 :조선해양공학과,2009.2.Docto

Differential Evolution을 利用한 船舶用 部材의 블록單位 네스팅

학위논문(석사)--서울대학교 대학원 :조선해양공학과,2004.Maste

소 바이러스성 설사병 바이러스 국내 분리주의 5`-untranslated region 염기서열 분석에 관한 연구

Thesis (master`s)--서울대학교 대학원 :수의학과 수의미생물학전공,2002.Maste

A Comparative Study on North Adolescent Migrants and South Korean Adolescents Political Attitude: Focused on political efficacy and political trust

학위논문 (박사)-- 서울대학교 대학원 : 사회교육과(일반사회전공), 2011.2. 모경환.Docto

Assessment of Diesel and JP-8 on Direct Injection Diesel Engine

An experimental study has been carried out to investigate the effect of diesel and JP-8 fuel on engine performance and emissions in a single cylinder heavy-duty diesel engine equipped with a production type cylinder head and a high pressure common-rail injection system, while macroscopic spray images were captured. Experiments were performed at various engine speed, injection pressure and injection timing for both fuels. It was found that spray tip penetration with JP-8 fuel is shorter than diesel fuel due to low viscosity characteristics of JP-8 fuel from macroscopic spray images analysis. Peak heat release rate was higher and premixed bum duration was longer with JP-8 fuel due to its better vaporization characteristics when fuel injection pressure was 300 bar. The result also showed that increase of injection pressure to 1400 bar was more dominant factor which influences combustion characteristics than difference of vaporization due to viscosity characteristics between diesel and JP-8 fuel

Applying Solenoid Valve and Metal Catalyst on the Exhaust Heat Exchanger to Reduce the light-off time in a SI Engine

Close-coupled catalyst (CCC) can reduce the engine cold-start emissions by utilizing the energy in the exhaust gas. However, in case the engine is operated at high engine speed and load condition, the catalytic converter may be damaged and eventually deactivated by thermal aging. Excess fuel is sometimes supplied intentionally to lower the exhaust gas temperature avoiding the thermal aging. This sacrifices the fuel economy and exhaust emissions. The heat exchanger was applied in an SI engine to lower the exhaust gas temperature mainly under high load conditions. The heat exchanger was installed between the exhaust manifold and the inlet of the CCC to avoid thermal aging. The exhaust heat exchanger successfully decreased the exhaust gas temperature, which eliminated the requirement of fuel enrichment under high load conditions. The amount of exhaust emissions (HC, CO, NOx) during the cold start increased due to the increment of the catalyst light-off time. This problem could be resolved by adopting the solenoid valve to cut off the coolant at the inlet of the coolant passage of the heat exchanger. New concept of heat exchanger which is combined with the metal catalyst was tested to investigate the possibility of reducing the light-off tim