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커먼레일 디젤기관에서 바이오디젤유(BDF 5%) 적용시의 내구특성 연구
최승훈,오영택,Choi, Seung-Hun,Oh, Young-Taig 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.2
Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engines are recognized as main causes of the air pollution. CRDI(common rail direct injection) diesel engine is widely used for the sake of minimization on exhaust emission. Because biodiesel fuel is a renewable and alternative fuel for diesel engine, its usability is expanded. In this study, a common rail diesel engine was run with 5% of biodiesel fuel(BDF 5%) more than 150 hours. Engine dynamometer testing was completed at regularly scheduled intervals to investigate the engine performance and exhaust emissions. The data of engine performance and exhaust emissions was sampled at 1 hour intervals for analysis. When a common rail diesel engine runs on BDF 5% for long time, power and energy consumption of the engine are similar to the case using diesel fuel. The smoke emission of BDF 5% was reduced in comparison with diesel fuel, that is, it was reduced approximately 15% at 4000rpm, and load of 90%. And, CO and $CO_2$ were reduced, too. On the other hand, NOx emission of biodiesel fuel was slightly increased about 2%, but it was almost same as a commercial diesel fuel.
함산소연료(DGM)와 EGR 방법이 디젤기관의 배기배출물에 미치는 영향에 관한 연구
최승훈,오영택,Choi, Seung-Hun,Oh, Young-Taig 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.12
In this paper, the combination effects of oxygen component in fuel and exhaust gas recirculation on the exhaust emissions have been investigated for a direct injection diesel engine. It is a kind of effective oxygenated fuel of diether group that the smoke emission of DGM(diethylene glycol dimethyl ether) blended fuel is reduced remarkably compared with commercial diesel fuel, that is, it can supply oxygen component sufficiently at higher loads and speeds in diesel engine. But, NOx emission of oxygenated fuel was increased compared with commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with oxygenated fuel(DGM 5vol-%) and cooled EGR method(10∼15%).
CRDI 방식 디젤기관에서 바이오디젤유 적용시 매연과 NOx의 동시저감에 관한 실험적 연구
최승훈,오영택,Choi, Seung-Hun,Oh, Young-Taig 한국자동차공학회 2007 한국 자동차공학회논문집 Vol.15 No.3
Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engine are recognized main cause which influenced environment strong, In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated common rail diesel engine. The smoke emission of biodiesel fuel 5vol-%(min. content) was reduced in comparison with diesel fuel, that is, it was reduced approximately 60% at 4000rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, NOx emission of biodiesel fuel was increased compared with a commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel(5vol-%) and cooled EGR method($5{\sim}10%$) in a common rail diesel engine.
저온소결 8/65/35 PLZT 세라믹의 전기열량 효과
최승훈,라철민,류주현,Choi, Seung-Hun,Ra, Cheol-Min,Yooa, Ju-Hyun 한국전기전자재료학회 2015 전기전자재료학회논문지 Vol.28 No.10
In this study, in order to develop the composition ceramics with the excellent electrocaloric properties, 8/65/35 PLZT ceramics were fabricated by the conventional solid-state method with the addition of $Bi_2O_3$, CuO, $Li_2CO_3$ and the variation of sintering temperature from $930^{\circ}C$ to $990^{\circ}C$. The XRD pattern of all specimens indicated general perovskite structure and the rhombohedral phase were observed. Curie temperature ($T_c$) of all specimens was observed in the vicinity of about $190^{\circ}C$. Density, coercive field and remnant polarization of the specimen sintered at $950^{\circ}C$ was $7.55g/cm^3$, 8.895 kV/cm, $11.22{\mu}C/cm^2$, respectively. EC effect of PLZT ceramics was measured by indirect method and the temperature change ${\Delta}T$ due to the electrocaloric effect was calculated by Maxwell's relations. ${\Delta}T$ of ceramic sintered at $950^{\circ}C$ was $0.21^{\circ}C$ under application of 40 kV/cm at $190^{\circ}C$.
최승훈(Choi, Seung Hun),함희정(Ham, Hee Jung),이승수(Lee, Sungsu) 한국방재학회 2020 한국방재학회논문집 Vol.20 No.5
본 연구에서는 산사면에서 붕괴로 발생하는 토석류에 대하여 조적과 콘크리트 건축물의 평균손상확률 형태의 취약성 곡선(Vulnerability Curve)을 건축물의 초과손상확률 형태의 취약성 곡선(Fragility Curve)을 기초하여 평가하였다. 건축물의 초과손상확률 형태의 취약성 곡선은 신뢰도 지수 기반의 해석적 접근 방법인 First-Order Second-Moment (FOSM) 방법을 이용하여 평가하였다. 이 방법에서 초과손상확률 형태의 취약성 곡선을 도출하기 위하여 토석류로 인한 건축물의 최대 수평변위와 건축물의 손상상태별(Slight, Moderate, Extensive, Complete) 저항성능(건축물의 수평변위)에 대한 통계치가 적용되었다. 건축물의 평균손상확률 형태의 취약성 곡선은 각 손상상태에 대한 초과손상확률 형태의 취약성 곡선과 평균 손상률(Mean Damage Ratio)을 이용하여 평가되었으며, 평가된 평균손상확률 형태의 취약성 곡선은 평균 제곱근 오차(Root Mean Square Error)를 이용하여 과거 토석류 피해자료와의 적합성을 검증하였다. 또한, 본 연구에서는 평가된 토석류에 대한 건축물의 취약성 곡선에 대하여 건축물의 구조 재료, 형태, 높이에 대한 영향성을 평가하였다. 본 연구에서 평가한 모든 취약성 곡선은 로그정규 누적분포함수의 형태로 곡선 맞춤 후 해당 모수의 형태로 데이터베이스화되었으며, 토사재해가 빈번한 지역에 있는 건축물의 구조적 성능을 평가하거나 위험도(Risk) 및 손실(Loss)을 평가할 시 활용될 수 있다. In this study, the vulnerability curves for masonry and concrete frame buildings are assessed based on building fragility curves for the debris-flow caused by landslides on mountain slopes. The First-Order Second-Moment (FOSM) method is used to estimate the building fragility curve (expressed as probability of damage exceedance) subjected to debris-flow. In this method, the horizontal displacement of a building impacted by debris-flow and the statistics of resistance (i.e., building displacement) following four different damage states (i.e., slight, moderate, extensive, and complete) are utilized to estimate the building fragility curve. The building vulnerability curves (expressed as mean probability of damage) were evaluated based on the estimated building fragility curve and corresponding mean damage ratio for each damage state and were verified by calculating the root mean square error with datasets obtained from post-disaster damage assessment. In this study, the effects of structural material, type, and height on the building vulnerability curves were also studied. All vulnerability curves of buildings estimated in this study were fitted and databased using parameters of the log-normal cumulative distribution function and can be used to measure the performance of buildings in debris-flow prone areas as well as to provide information for risk and loss assessment.
최승훈(Choi, Seung Hun),함희정(Ham, Hee Jung),이승수(Lee, Sungsu) 대한건축학회 2021 대한건축학회논문집 Vol.37 No.11
In this study, a methodology is developed to evaluate vulnerability (mean damage probability) curves of debris-flow for low/mid-rise buildings based on the fragility (exceedance damage probability) curves and mean damage ratio (MDR). In order to evaluate fragility curves, First Order Second Moment (FOSM) method is applied in this study. In the FOSM method, the maximum horizontal displacement of the building caused by the static and dynamic loadings of debris-flow is estimated as the effect of the external force, and the median/log-standard deviation values of spectral displacement of earthquake fragility of buildings developed by National Emergency Management Agency (NEMA) are used as the resistance statistics. MDR of the building subjected to the load of debris-flow is established based on literatures of the post investigations of debris-flow and landslide disasters, and is applied to convert the fragility curve to vunerability curve. 32 different types of vulnerability curves for buildings are databased as the variables of log-normal cumulative distribution function (CDF) after calibration and correction with the available post-disaster data sets. The vulnerability curves developed in this study may be used for risk and loss assessment of buildings subjected to debris-flow hazards. The developed methodology can be also applied if information of the fragility is available and the vulnerability has to be estimated from the fragility.