Characterization study of biomass charcoals with explosive combustion characteristics

Byungchul Choi(최병철),Moonyong Kim(김문용),Gyeong-gap Jung(정경갑),Sungchun Byun(변성천) 한국연소학회 2019 KOSCOSYMPOSIUM논문집 Vol.2019 No.11

Development of a combined system of LNT/CDPF and SCR/DPF for diesel engine

Byungchul Choi(최병철) 한국자동차공학회 2013 한국자동차공학회 Workshop Vol.2013 No.6

CTALYTIC OXIDATION OF PARTICULATE MATTERS (PM) FROM DIESEL ENGINES

Byungchul Choi,Jong-Woo Jeong 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-

The paper summarizes the key developments in diesel emission control, especially particulate matter. Increasing attention is being paid to the particulate matter (PM) emissions form diesel vehicles, which consists mostly of carbonaceous soot and a volatile organic fraction (VOF) of hydrocarbons that have condensed on the soot. There is growing concern about these emissions, since emerging evidence potentially implicates PM as a major pollutant associated with acute health effects. Regarding ultrafines PM, studies are emerging which provide chemical detail as a function of size fraction, and more is known about the structure and reactivity of soot. Filter technology is focusing on optimization, with work being done on better ways to regenerate the filter and improve system back pressure and durability. System integration of filters and NOx control is in road testing for heavy duty applications using SCR. DPF+LNTs help prototype light-duty diesels comfortably attain the tightest future regulations. This paper also introduces our current work exerted to investigate the characteristics of diesel exhaust gas emissions and performance of catalytic converter systems on the conditions of engine operation and fuel mixtures.

Effects of hydrothermal aging on SiC-DPF with metal oxide ash and alkali metals

Byungchul Choi,Bao Liu,Jong-Woo Jeong 한국공업화학회 2009 Journal of Industrial and Engineering Chemistry Vol.15 No.5

The silicon carbide used to make diesel particulate filters (SiC-DPF) has a maximum temperature of use, which is not the melting point of the filter material itself but rather the eutectic melting points of the ash materials and alkali metals deposited on the filter wall. Chemical reactions between the SiC filter and the other materials, i.e. ash materials and/or alkali metals, decrease the filtration efficiency and catalytic reactivity of engine out emission. The objective of this study is to understand the effect of hydrothermal aging on the SiC-DPF, and on the SiC-CDPF (catalyzed diesel particulate filter) deposited with ash materials and/or alkalimetals. Hydrothermal aging simulated for the extreme condition of uncontrolled regeneration in DPF is carried out by using H2O at high temperature. The surface change of the SiC filter was characterized in terms of the geometric microstructure and metal composites of the filter by using the SEM-EDS, BET and XRD. The accumulated ash materials and alkali metals in the SiC-DPF were an admixture, and the SiC-DPF after-treatment system always contained H2O. According to the results, H2O in the after-treatment system can be regarded as an influential factor of SiC-DPF durability even though the SiC itself has a very high melting point. The regeneration temperature has to be controlled under a critical value to ensure the durability of SiC-DPF in the after-treatment system, considering the fact that large quantities of ash materials, alkali metals and H2O components are included in the exhaust gas.

Effects of additives Co, La, and Mn for Pt-based carbon oxidation catalysts

Byungchul Choi 한국공업화학회 2008 Journal of Industrial and Engineering Chemistry Vol.14 No.4

Catalyzed diesel particulate filter (CDPF) systems are viewed as the next generation after-treatment system for the diesel vehicle. The CDPF was coated with Pt catalyst to regenerate particulate matters (PM) continuously. This study was conducted to investigate the PM oxidation catalyst for the CDPF system. The promotional effects of additives Co, La, and Mn for Pt-based carbon oxidation catalysts are investigated by a model gas test. The order of temperature that CO formation happens sharply was Mn < Pt < Pt2 < La < Co, from low temperature to high temperature order. The additive Mn was able to decrease carbon oxidation temperature by 10 8C more than the Pt-only catalyst. The additive Mn has the advantage of generating CO, and it may have the possibility of NOx reduction. Coexistence of both C3H8 and carbon in CDPF (catalyzed DPF) may be helpful to activate the rate of carbon oxidation over the catalyst sites.

Effect of diesel fuel blend with n-butanol on the emission of a turbocharged common rail direct injection diesel engine

Choi, Byungchul,Jiang, Xiaolong,Kim, Young Kwon,Jung, Gilsung,Lee, Chunhwan,Choi, Inchul,Song, Chi Sung Elsevier 2015 APPLIED ENERGY Vol.146 No.-

<P><B>Abstract</B></P> <P>The objectives of this study are to investigate the effect of diesel fuel blend with n-butanol on the emission of turbocharged common rail direct injection (CRDI) diesel engine and to compare the results with the neat diesel fuel operation case. The blends considered here were blends of diesel fuels with 10% and 20% (by volume) n-butanol. Engine performance and emission characteristics were measured by the European Stationary Cycle (ESC) test. Emissions of HCs, CO, NOx, HCHO, HCOOH and NH<SUB>3</SUB> were measured by Fourier Transform Infrared Spectroscopy (FTIR). Size and number distribution of particulate matter (PM) were measured by the Scanning Mobility Particle Sizer (SMPS). From the results, for the n-butanol blend, NOx emission increased compared with the neat diesel fuel case. At the case of 20% butanol, both THC and CO emissions increased significantly, and both HCHO and HCOOH increased modestly under the low loading of ESC 7, 9 and 11 mode compared with the neat diesel fuel case. Higher blending ratio (>20%) of butanol fuels could contribute to the precursor of PAHs formation such as toluene and benzene in diesel combustion. BU5 blend could be a better option to reduce the PM mass and the emissions of nanosized PM under 50nm.</P> <P><B>Highlights</B></P> <P> <UL> <LI> For the n-butanol blend, NOx emission increased compared with the neat diesel fuel case. </LI> <LI> At the case of 20% butanol, THC and CO emissions increased significantly, and HCHO increased in the low loading conditions. </LI> <LI> Higher blending ratio (>20%) of butanol fuels contributes to the precursor of PAHs formation such as toluene. </LI> <LI> BU5 blend could be a better option to reduce the PM mass and the emissions of nano-sized PM under 50nm. </LI> </UL> </P>

Linking Multidimensional Performance Feedback and the Type of Exploration: A Behavioral Perspective

Byungchul Choi,Shyam Kumar 한국인사조직학회 2017 한국인사ㆍ조직학회 발표논문집 Vol.2017 No.1

The behavioral theory of the firm proposes that performance–aspiration gaps significantly affect search behavior. While the theory proposes that various performance dimensions matter in organizations, in the context of innovation the research has predominantly focused on financial performance metrics. In this study, we draw on insights from the ‘multiple performance dimension’ perspective to examine how technological performance and financial performance simultaneously determine a firm’s exploration behavior through shaping organizational states. We first introduce four types of organizational state by combining technological and financial performance feedbacks. Then, we propose that while financial performance feedback delimits the scope of technological boundary of exploration (technological domain) while technological performance feedback influences the organizational emphasis toward organizational boundary of exploration (Knowledge base). Using patent and financial data from 150 firms in high-tech industries of the U.S. during 1995-2002, we provide support for our arguments. We find that different organizational state leads organizations to focus more on a certain types of exploration. Therefore, a firm’s exploration behavior can vary in accordance to organizational states conjointly formed by feedbacks from financial performance and technological performance. Our study offers the potential for bridging two theoretical perspectives, the behavioral theory of the firm and explorative search with a richer range of organizational states and actual technological trajectory of exploration.

자동차 실내 공기 살균을 겸한 저온 플라즈마 광촉매 정화기 개발

최병철(Byungchul Choi),김창환(Changhwan Kim),김철호(Cheolho Kim),이경석(Kyungseok Lee) 한국자동차공학회 2021 한국자동차공학회 부문종합 학술대회 Vol.2021 No.6

자동차 실내 공기 오염문제에는, 신차의 경우 새차증후군 문제, 도심 주행 시에는 대기 중 오염이 외기순환을 통해 유입하는 등이 있다. 외부에 COVID 19나 독감 등이 존재할 때 이들의 내부 침입 및 흡착으로 운전자의 건강을 해칠 수 있다. 이 연구의 목적은 약 10W의 전력으로 자동차 실내 유입 공기 혹은 내부 순환하는 공기 중 유기성분, 세균, 바이러스를 제거할 수 있는 저온 플라즈마 광촉매 공기정화기를 개발하는 것이다. 광촉매에 사용되는 TiO₂의 특징은 그 에너지구조로 인해 전도대로 여기된 전자가 갖는 환원력보다 정공(h⁺)이 갖는 산화 분해력이 강하며, 물이 정공과 반응하여 산소 가스를 발생시키기도 하지만, 표면에 유기물이 있으면 유기물을 산화 시키는 에너지 전위로 산화 분해 시켜 이산화탄소를 만든다. 광촉매 표면에 물이 흡착되면 물은 정공(h⁺)에 의해 산화되면 산화 분해력이 높은 OH^-라디칼이 되며, 이 표면에 오염물이나 세균, 악취물질 등 유기화합물은 이 라디칼과 반응하여 CO₂를 생성한다(Fig. 1 참조). Fig. 2는 플라즈마 광촉매장치의 반응시간에 따른 200 L 내 C<SUB>3</SUB>H<SUB>8</SUB>(67 ppm), NO (16 ppm)의 저감 특성이며, 포화 탄화수소 C<SUB>3</SUB>H<SUB>8</SUB>은 반응 시간 20 시간에 거의 100%로 정화되었다. 그리고 NO는 2시간에 거의 정화되었는데, 이는 NO가 광촉매 반응에 의해 HNO₃로 변형되어 촉매 표면에 흡착되었기 때문이다. 플라즈마 광촉매 장치의 최고 소비 전력은 4.25W이었으며, 이 때 오존 배출 농도가 약 0.3 ppm이고, 오존의 최고정화율은 약 67%이었다. 광촉매 공기정화기를 통과한 공기 중 배양지의 딸기곰팡이균의 성장은 대기 중에 노출된 것보다 성장속도가 느렸다.

무자본 M&A 규제의 필요성에 대한 연구 : 상장폐지 사례를 중심으로

최병철 ( Byungchul Choi ),변정윤 ( Jungyoon Byun ),문두철 ( Doocheol Moon ) 한국회계학회 2018 회계저널 Vol.27 No.2

기업의 M&A(Mergers and Acquisitions)는 구조조정과 경영혁신을 통한 시너지효과를 창출해 냄으로써 기업의 생존과 성장을 담보하는 가장 중요한 경영 전략이다. 이 과정에서 기업은 인수 자금의 일정 부분을 차입하여 해당 기업을 인수하는 방법을 사용하기도 하는데, 무자본 M&A의 경우에는 자체 자본이 전혀 없이 전체 인수 자금을 차입하여 해당 기업을 인수하는 더욱 극단적인 M&A 방법이라고 볼 수 있다. 더 나아가 최근에는 외부에서 차입한 자금이 아닌 인수 대상 기업의 자산을 이용해 기업을 인수하는 새로운 형태의 무자본 M&A가 발생하고 있는데 이러한 무자본 M&A는 인수·합병의 긍정적인 효과를 기대하기 어려울 뿐만 아니라 투자자 피해를 일으킬 수 있다. 이에 본 연구는 무자본 M&A 사례에 대하여 분석해 보고 무자본 M&A를 악용하는 사례를 예방할 수 있는 제도적 안전장치의 필요성을 제시하고자 한다. 구체적으로 코스닥 상장기업인 마제스타 및 골든레인이 엠제이비를 무자본으로 인수하였다가 결국 상장폐지되어 투자자들에게 큰 피해가 발생했던 M&A 사례에 대하여 재무제표 자료, 외부감사인의 감사의견 내용 등을 이용하여 분석하였다. 본 연구는 기업 인수·합병 시 발생하는 변칙적 형태의 거래들을 제재하여 건전한 자본시장을 만들어 가기 위한 규제당국의 면밀한 모니터링의 필요성과 규제의 필요성을 제시하는데 그 의의가 있다. 또한 본 사례를 통하여 무자본 M&A에 대한 투자자 및 정보이용자들의 주의를 환기시킴으로써 회계 교육에도 공헌할 수 있을 것으로 판단된다. M&A is one of important management strategies for a company to guarantee its survival and growth by creating synergy effect through structural adjustment and management innovation. However, M&A without any capital is more extreme case than Leveraged Buyout(LBO) in that an acquiring firm borrows whole amount of money to meet cost of acquisition. Furthermore, nowadays, the acquiring firm even uses the acquired firm’s assets to raise cost of acquisition, which is a new type of M&A without capital investments. This kind of M&A not only cannot bring positive effects for acquiring companies but also damage investors’ wealth. Thus, we analyze recent M&A cases occurred without capital, and suggest such M&A methods should be regulated by regulation authorities. To be specific, we analyze how Majesta and Golden rain acquired MJB without capital based on financial statements and audit report information. We suggest that irregular transactions should be restricted for capital market soundness when M&A is occurred. Also, we call information users’ attention to M&A without capital, and contribute to accounting education by recognizing the importance of accounting information and financial statement analysis.

원관내 CH₄-air 예혼합기의 화염전파속도에 미치는 수소 첨가율의 영향

최병철(Byungchul Choi),양경철(Kyeongcheol Yang),이건석(Lee Geonseok),오영환(Younghwan Oh) 한국자동차공학회 2015 한국자동차공학회 지부 학술대회 논문집 Vol.2015 No.4