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바이오디젤유(미강유 에스테르)를 이용한 농업용 디젤기관의 연소 특성
유경현,윤용진,오영택,Ryu, Kyung-Hyun,Yun, Yoong-Jin,Oh, Young-Taig 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.2
Biodiesel fuel as an alternative fuel for diesel engine has a great possibility to solve the problems such as air pollution. It is a domestically produced, renewable fuel that can be manufactured from vegetable oils, used vegetable oils, or animal fats. In this study, the usability of biodiesel fuel derived from rice bran oil as an alternative fuel for diesel engines was investigated in agricultural diesel engine. Emissions were characterized with neat biodiesel fuel and with a blend of biodiesel fuel and conventional diesel fuel. Since the biodiesel fuel includes oxygen of about 11%, it could influence the combustion process strongly. So, the use of biodiesel fuel resulted in lower emissions of carbon monoxide, carbon dioxide, and smoke emissions without any increase of oxides of nitrogen. It is concluded that biodiesel fuel can be utilized effectively as a renewable and an environmentally Innocuous fuel for diesel engine.
바이오디젤-CNG 혼소 엔진시스템에서 압축비가 성능 및 연소 특성에 미치는 영향
유경현,원종근 한국자동차공학회 2024 한국 자동차공학회논문집 Vol.32 No.2
This paper explores the effects of compression ratio on the performance and emission characteristics of abiodiesel-CNG dual-fuel combustion system in a single-cylinder direct injection diesel engine. Engine tests were conducted with the compression ratios(CR) of 14.5 and 16.5 at an engine speed of 1,700 rpm and various engine loads. This study showed that the cylinder pressure peak of the dual-fuel combustion decreased as CR decreased. The ignition delay periods of the pilot fuel at CR 14.5 increased compared to those at CR 16.5. For maximum output, the pilot injection timing of CR 14.5 should be advanced approximately by 5 % compared to CR 16.5. Engine operation became stable with a COVimep of 3 % at CR 14.5, except when there is no load. The biodiesel-CNG dual-fuel combustion system reduced smoke emissions compared to a conventional single-fuel diesel combustion system. As CR decreased, smoke emission also decreased.
Papaverine이 단일 심근세포의 막전류에 미치는 영향
유경현,심태섭,방효원 중앙대학교 의과대학 의과학연구소 1991 中央醫大誌 Vol.16 No.4
Ventricular myocytes of guinea-pig were isolated by means of collagenase digestion in order to investigate the effects of papaverine on the membrane currents in them. After formation of a gigaseal with patch microelectrodes, membrane currents were recorded from single ventricular myocytes in a whole cell mode of patch-clamp technique. For membrane currents recording, electrodes were filled with Cs-solution. Results were as follows: 1. Slow inward calcium was reduced by papaverine dose-dependently. 2. No significant changes were observed in the steady-state inactivation. 3. Recovery time of the calcium currents prolonged in high concencial papaverine. 4. Fast inward sodium currents showed no noticeable changes with papaverine treatment. From these results, it is strongly suggested that the effects of papaverine on the membrane currents in the single ventricular myocytes may be attributable to its antagonistic action on the calcium channel rather than its inhibitory effect on the phosphodiesterase activity.
유경현,오영택,Ryu, Kyung-Hyun,Oh, Young-Taig 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.3
Three diesel engines were fueled with BDF 20, a blend of 80% diesel fuel and 20% biodiesel fuel by volume, and run in excess of 200 h to evaluate their combustion characteristics and durability. The engines used for this study were a 4-cylinder 2476-cc displacement IDI diesel engine(Engine 1), a 4-cylinder l732-cc displacement IDI diesel engine(Engine 2), and a single cylinder 673-cc displacement DI diesel engine(Engine 3). Engine dynamometer testing was performed on each engine at regularly scheduled intervals to monitor the performance and exhaust emissions, which were sampled at 1h intervals for analysis, The peak combustion pressure with BDF 20 increased in Engines 1 and 3 over that measured when burning pure diesel fuel, but that in Engine 2 remained constant. Combustion parameters, such as the maximum combustion pressure and corresponding crank angle, did not change over the long-term dynamometer testing. The BSFC with BDF 20 in Engine 1 was less than that measured with pure diesel fuel. The amount of smoke produced with BDF 20 was less for all engines ; the greatest reduction was observed for Engine 3. The NOx emissions were lower in the IDI engines than the DI engine. The traditional trade-off between smoke and NOx emissions was maintained for BDF 20 fuel for Engines 1 and 3. There was not a big difference in the $CO_2\;and\;O_2$ emissions for BDF 20, as compared to pure diesel fuel, but more $CO_2$ was exhausted by Engine 1 than by Engines 2 or 3 and less $O_2$ was exhausted by Engine 1 than by Engines 2 or 3. The engine parts remained clean, except for some carbon attached to the area surrounding the nozzle hole of the DI diesel engine.
유경현 한국공학교육학회 2020 공학교육연구 Vol.23 No.4
Capstone design education is essential in the engineering design process according to the certification standards of ABEEK. Capstone design process should be properly trained in undergraduate courses in order to increase the design ability of systems, components and processes within realistic constraints. In this study, a modified design model as a capstone design education model was proposed to reduce the separation between the design process at industrial sites and the design process at university education. The modified design model based on 6-sigma methodology is composed of 6 design steps such as define, measure, analyse, design, verify, and report. Each step has appropriated design contents and tools, and is configured to generate design results. The proposed design model was directly applied to the capstone design class for automotive engineering in Kunsan National University, and it was confirmed that the proposed DMADVR methodology was a very useful design education model to enhance the design ability, teamwork ability and communication skills required by ABEEK.