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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.
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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.
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흡기관내로의 물 분사에 의한 디젤기관의 연소특성 (I)
유경현,윤용진,오영택,Ryu, Kyung-Hyun,Yun, Yoong-Jin,Oh, Young-Taig 대한기계학회 2002 大韓機械學會論文集B Vol.26 No.12
To effectively meet current regulations on the exhaust emissions of diesel engine required to control the deterioration of air pollution in the whole world, this study is to investigate the effects of water induction through the air intake system on the characteristics of combustion and exhaust emissions in IDI diesel engine. A method fur supplying water through the air intake system to reduce the exhaust emissions has been considered with other methods such as water introduction in the form of water-in-fuel emulsion or water injection directly into the combustion chamber, but it has not been studied about the effects of water on the combustion concepts and the characteristics of exhaust emissions in detail until now. In this study, the formation of NOx was significantly suppressed by decreasing the gas peak temperature during the initial combustion process because the water play a role as a heat sink during evaporating in the combustion chamber, but the smoke was slightly increased by increasing water amount.
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유경현 대한기계학회 2009 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.23 No.11
Biodiesel fuels that consist of saturated and unsaturated long-chain fatty acid alkyl esters are an alternative diesel fuel produced from vegetable oils or animal fats. However, autoxidation of biodiesel fuels during storage is easily caused by air, reducing fuel quality by adversely affecting its properties such as kinematic viscosity and acid value. One approach to improve the resistance of biodiesel fuels to autoxidation is to mix them with antioxidants. This study investigated the effectiveness of five such antioxidants in mixtures with biodiesel fuels produced by three biodiesel manufacturers: butylated hydroxytoluene (BHT), butylated hydroxyanisole (BHA), tert-butylhydroquinone (TBHQ), propyl gallate (PrG) and α-tocopherol. An engine test was also performed to investigate the combustion characteristics of biodiesel fuel with antioxidants in an indirect-injection (IDI) diesel engine. Oxidation stability was determined using Rancimat equipment. The results showed that TBHQ, BHA, and BHT were the most effective and α-tocopherol was the least effective in increasing the oxidation stability of biodiesel. The combustion characteristics and exhaust emissions in diesel engine were not influenced by the addition of antioxidants in biodiesel fuel. This study recommends TBHQ and PrG to be used for safeguarding biodiesel fuel from the effects of autoxidation during storage.
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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.
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