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.

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.

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%).

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 $190^{\circ}C$.

토석류에 대한 건축물의 취약성 곡선 평가

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.

이기종 서버들에서 주변 온도를 고려한 비디오 트랜스코딩

최승훈(Seung Hun Choi),송민석(Minseok Song),정성우(Sung Woo Chung) 한국컴퓨터정보학회 2020 한국컴퓨터정보학회 학술발표논문집 Vol.28 No.2

텍스트 마이닝을 통한 메타버스 아바타 성착취 처벌에 대한 대중의 인식 분석

최승훈 ( Seung Hun Choi ),조은경 ( Eunkyung Jo ) 대한범죄학회 2024 한국범죄학 Vol.18 No.1

가상현실 기술 발전에 따라 현실과 더욱 유사한 몰입 경험을 제공하는 기기들이 출시되고 있는 상황에서, 새로운 유형의 문제 행위인 아바타 성착취에 대한 논의는 필수적이다. 이에 본 연구는 상대 아바타를 대상으로 성(性)적 행위를 가한 이용자를 법적으로 처벌하는 방안에 대한 대중의 인식을 파악함으로써, 아바타 성착취 대응책 관련 논의에 일조하고자 한다. 이 연구에서는 주된 온라인 커뮤니티 채널이자, 사람들의 대표적인 의사 표현 공간 중 하나인 유튜브를 분석 채널로 선정하여 사용자들의 댓글에 나타난 인식을 분석하였다. 유튜브 채널 내에서 ‘아바타 성착취 처벌’을 다룬 영상 13개를 선별한 뒤, Python 3.9 개발도구를 활용하여 2024년 2월 19일까지 작성된 댓글(N=1,321)에서 10,201개의 단어를 추출하였다. 텍스트 마이닝 기법 중 빈도분석과 LDA 토픽 모델링 기법을 활용하여 추출한 데이터를 분석한 결과, ‘게임 상황으로 인식-비판적’, ‘게임 상황으로 인식-이용자의 직접적인 대응책 제시’, ‘외부적 규제 방법 제시’, ‘단순 비난’, ‘아바타 인격화’ 등 총 5개의 토픽으로 분류되었다. 아바타 성착취에 대한 처벌의 필요성을 다룬 영상에 대해 대다수의 댓글이 회의적이거나 비판적인 경향을 보였다. 또한 댓글 내용을 살펴보았을 때, 가상 세계에서 발생한 아바타 성착취를 여러 일반 게임 내의 상황과 동일시하는 의견과 해당 범죄의 대응책으로서 법률적인 제재보다는 플랫폼 운영자의 규제 혹은 이용자의 직접적인 대응책을 제안하는 의견이 많았다. 이에 본 연구는 아바타 성착취 법적 처벌의 필요성과 타당성에 대한 사회적 합의가 부족하다는 점을 강조하고 처벌에 대한 논의에 앞서 먼저 이루어져야 할 전제조건들을 제안하였다. With the development of virtual reality technology and the release of devices offering more lifelike experiences, it’s essential to discuss newly emerging avatar sexual abuse crimes. This study intends to contribute to the discussion on countermeasures against avatar sexual abuse crimes by grasping the public’s opinions regarding the punishment of users who engage in sexual activity against other avatars. In this study, 13 YouTube channel videos about avatar sexual abuse were selected and 1,321 user comments were analyzed using text mining analysis techniques. Python 3.9 development tools were used for frequency analysis and LDA topic modeling on 10,201 words extracted from the user comments. Five topics of user comments were identified: ‘Game Situation-Skeptic’, ‘Game Situation-User’s Own Countermeasure’, ‘External Regulation’, ‘Simple Criticism’, and ‘Avatar Personalization’. Most comments tended to be skeptical or critical of the videos advocating legal punishment of avatar sexual abusers. In addition, many users equated avatar sexual abuse in the virtual world with situations in general video games and suggested regulation of platform operators or users’ own countermeasure against the crime rather than introducing legal punishment. Based on these results, more discussions are needed to draw social consensus on the necessity and legitimacy of legal punishment for avatar sexual abuse offenders.

CI기관에서 바이오디젤의 혼합율에 따른 배기배출물 특성 연구

최승훈(Seung-Hun, Choi) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.5-3

자연재해 취약성 저감대책 수립을 통한 건축물 취약성 지수 영향성 분석

최승훈(Choi, Seung Hun),함희정(Ham, Hee Jung),이승수(Lee, Sungsu) 대한토목학회 2021 대한토목학회 학술대회 Vol.2021 No.10

저 · 중층 건축물에 대한 토석류 취약도 평가

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.