Reusing the Optimized Code for JavaScript Ahead-of-Time Compilation

Park, Hyukwoo,Kim, Sungkook,Park, Jung-Geun,Moon, Soo-Mook Association for Computing Machinery 2018 ACM transactions on architecture and code optimiza Vol.15 No.4

Simultaneous reduction in the exhaust emissions by a high exhaust gas recirculation ratio in a dimethyl-ether-fuelled diesel engine at a low-load operating condition

Park, Su Han,Cha, Junepyo,Park, Sungwook,Lee, Chang Sik SAGE Publications 2012 Proceedings of the Institution of Mechanical Engin Vol.226 No.8

<P>The purpose of this study was to investigate the effect of the exhaust gas recirculation rate on the combustion and exhaust emission reduction characteristics of dimethyl ether fuel in a single-cylinder diesel engine. To investigate the effects on emission reduction, the test set-up was composed of a dimethyl ether supply system, a spray visualization system, an engine combustion system and an emissions analysis system. In this work, the spray visualization and exhaust emissions were measured using a high-speed camera with a metal halide lamp, a smoke meter and an emission gas analyser. The spray tip penetration and tip velocity of dimethyl ether fuel were lower than those of conventional diesel fuel. The reduction slope of the spray cone angle for dimethyl ether was less than that for diesel fuel owing to its low density and superior evaporation characteristics. The increase in the exhaust gas recirculation rate caused an extension of the ignition delay for dimethyl ether. During the extended ignition delay, the improved mixing characteristics influenced the slight decrease in the combustion period. An increase in the exhaust gas recirculation rate caused a significant reduction in the emission of nitrogen oxides. In addition, the soot emission was very low owing to the intrinsic characteristics of dimethyl ether (no direct carbon-carbon bonds). At the given equivalence ratio condition, the indicated specific hydrocarbon and indicated specific carbon monoxide emissions for dimethyl ether were extremely low when dimethyl ether spray was injected into the piston bowl (from 25 degrees before top dead centre to top dead centre). Also, in this case, a change in the exhaust gas recirculation rate for dimethyl ether combustion had minimal effects on the indicated specific hydrocarbon and indicated specific carbon monoxide emissions. These results suggest that the use of high exhaust gas recirculation with dimethyl ether fuel can achieve near-zero exhaust emissions (nitrogen oxides, soot, hydrocarbons and carbon monoxide).</P>

Demolding temperature in thermal nanoimprint lithography

Park, Sunggook,Song, Zhichao,Brumfield, Lance,Amirsadeghi, Alborz,Lee, Jaejong Springer-Verlag 2009 APPLIED PHYSICS A MATERIALS SCIENCE AND PROCESSING Vol.97 No.2

Prediction of wall impingement in a direct injection spark ignition engine by analyzing spray images for high-pressure injection up to 50 MPa

Park, Junkyu,Kim, Taehoon,Kim, Donghwan,Park, Sungwook Elsevier 2018 Fuel processing technology Vol.179 No.-

<P><B>Abstract</B></P> <P>This study was performed to analyze the wall impingement and fuel film formation in a DISI engine with injection strategies using image-based analysis and CFD. The direct injection engine uses a high-pressure injection strategy to improve the homogeneity of the air-fuel mixture, so the spray behavior was analyzed by spray visualization for various injection pressures, and the wall impingement was predicted for various engine operating conditions based on the acquired images. The mass distribution of the injected fuel was calculated using the injection profiles and the spray image, and the amount of fuel that impinges on the piston and wall (i.e., the geometric boundaries of the cylinder) was calculated using data from the spray behavior for various engine operation conditions such as load and engine speed. The image-based analysis was limited to understanding the influence of the injection strategy on the droplet behavior after wall impingement of the fuel spray. Therefore, CFD using KIVA 3 V code was additionally conducted to analyze the effects of the injection strategies on wall film formation and droplet rebounding reflecting in-cylinder conditions. In the early- and late-injection conditions, the initial piston position is high, and most of the injected fuel impinges on the piston. As the injection pressure increases, the injection timing at which wall impingement occurs is advanced because of the rapid spray development. The results of the 3D analysis for the temperature and the intake flow in the engine cylinder showed that both the wall impingement and the fuel film were reduced as the injection pressure increased because the fuel evaporation increased due to improved atomization.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A prediction method of wall impingement in DISI engines is introduced. </LI> <LI> Effects of injection pressure and injection timing on spray wall impingement are analyzed using image-based method. </LI> <LI> 3D CFD are used to analyze effects of the engine conditions on formation of fuel film. </LI> <LI> Higher injection pressure conditions can reduce formation of fuel film due to superior vaporization characteristics. </LI> </UL> </P>

Detection of Avian Influenza Virus from Cloacal Swabs Using a Disposable Well Gate FET Sensor

Park, Sungwook,Choi, Jaebin,Jeun, Minhong,Kim, Yongdeok,Yuk, Seong-Su,Kim, Sang Kyung,Song, Chang-Seon,Lee, Seok,Lee, Kwan Hyi Wiley (John WileySons) 2017 Advanced Healthcare Materials Vol.6 No.13

Spontaneous reduction of Cr(VI) using InSnS₂ under dark condition

Park, Sungmook,Kim, Woolcheol,Selvaraj, Rengaraj,Kim, Younghun Elsevier 2017 Chemical engineering journal Vol.321 No.-

<P><B>Abstract</B></P> <P>The flower-like In<SUP>3+</SUP>-doped SnS<SUB>2</SUB> (InSnS<SUB>2</SUB>) was synthesized by microwave-assisted method for the photoreduction of toxic Cr(VI) to less-toxic Cr(III). InSnS<SUB>2</SUB> showed a narrow bandgap (2.0eV) and a broad spectrum response (400–800nm), suitable to apply the photocatalytic reduction of Cr(VI) under visible-light irradiation. In our latest report, we found that the enhanced photocatalytic activity was caused by the indium doping and the formic acid, which acted as the inhibitor to hole–electron recombination and hole scavenger, respectively. Herein, as a further study, the contact time of Cr(VI) with InSnS<SUB>2</SUB> in the dark condition was adjusted to ensure the adsorption–desorption equilibrium, and its effect on the reduction activity was evaluated. The results show that spontaneous reduction of Cr(VI) was observed in the initial adsorption process in the dark condition via the synergistic effect of In<SUP>3+</SUP> release and HCOOH, and at later the reduction of Cr(VI) only occurred by the photocatalytic reaction under visible-light irradiation. Finally, the adsorption of Cr(VI) on photocatalyst before light irradiation was found as an important factor to enhance the photoreduction of Cr(VI).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Microwave-assisted synthesis of In<SUP>3+</SUP> doped SnS<SUB>2</SUB> as visible-light-driven photocatalyst. </LI> <LI> Spontaneous reduction of Cr(VI) in dark condition via the synergistic effect of In<SUP>3+</SUP> and HCOOH. </LI> <LI> Indium-doping and formic acid acted as inhibitor of hole–electron recombination and hole scavenger. </LI> <LI> Adsorption before light irradiation on photocatalyst was important factor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

CsPbX3/SiOx (X = Cl, Br, I) monoliths prepared via a novel sol-gel route starting from Cs4PbX6 nanocrystals

Park, Sungwook,An, Mai Ngoc,Almeida, Guilherme,Palazon, Francisco,Spirito, Davide,Krahne, Roman,Dang, Zhiya,De Trizio, Luca,Manna, Liberato The Royal Society of Chemistry 2019 Nanoscale Vol.11 No.40

<P>We developed a facile synthesis of nanocomposite powders of CsPbX3 nanocrystals (NCs) embedded in silica. The synthesis starts from colloidal Cs4PbX6 NCs that are mixed with tetraethyl orthosilicate in the presence of nitric acid, which triggers the sol-gel reaction yielding the formation of SiOx and the conversion of starting NCs into CsPbX3 ones. The overall reaction delivers CsPbX3 NCs encased in a silica matrix. The resulting CsPbX3/SiOx nano-composite powders exhibited enhanced moisture and thermal stability in air. Also, when mixing different CsPbX3/SiOx samples having diverse anion compositions, no interparticle anion exchange processes were observed, which is a further indication that the silica matrix acts as a robust barrier surrounding the NCs. Finallly, we used these composites as down-converter phosphors on top of a blue light-emitting diode (LED), delivering nearly ideal white light emission with the Commission Internationale de l'Eclairage (CIE) color coordinates (0.32, 0.33).</P>

Mission at the Roundtable of diversity in God’s Mission

PARK SungKook 성공회대학교 신학연구소 2013 Madang: Journal of Contextual Theology Vol.19 No.-

“Asia” has been known as the icon and expression of “Variety”, “Diversity” and “Cultural richness”. Asia – as a continent – forms the largest piece of soil on earth and is home to almost 4 billion people. Economically, Asia is a continent that reflects the most paradox phenomena: While certain countries are regarded as the most affluent ones in the world, the Asian continent also shows in some of its parts, the lowest income and hence, the poorest among the poor. Following their economical standards the gap between different technically equipped and non- or less equipped is evident: While some of the countries in Asia are praised to be equipped with one of the most sophisticated technical achievements in the human history, some regions in Asia show serious ‘underdevelopment’ in these respective terms. And historically, Asia is a wound-driven continent where most of the countries in Asia bear dark memories of being exploited in the past, and still many are still getting exploited. The term “cultural richness”, expresses itself in a huge variety of diverse forms of cultures; different languages (probably the most languages in numbers in the world) and different religions and religious practices. We may witness the oldest forms of human settlements (or civilization) up to the youngest developed industrial powers in Asia. In Asia we witness a wide spectrum from politically stable democratic countries to unstable, almost fragile countries; peaceful regions but also frequently or even constantly conflict driven places; regions that never have been affected by calamities or disasters, but also regions where calamities or disasters are almost like on the ‘daily agenda’.

여성 문해학습자의 학업스트레스와 문해교육 프로그램 적응과의 관계에서 자기자비의 조절효과

박성숙(Sungsook Park),손영민(Youngmin Son) 중앙대학교 한국교육문제연구소 2020 한국교육문제연구 Vol.38 No.1

본 연구는 여성 문해학습자의 학업 스트레스와 문해교육 프로그램 적응의 관계에서 자기자비가 조절효과를 나타내는지 알아보고, 여성 문해학습자가 잘 적응할 수 있는 방안 마련을 목적으로 실시되었다. 강원도 지역 10개 기관 여성 문해학습자 247명의 응답지를 최종분석에 사용하였고, 변인 간의 상관분석과 학업스트레스가 문해교육 프로그램 적응에 영향을 주는데 있어서 자기자비가 조절역할을 하는지 살펴보았다. 분석결과 문해교육 현장에서 고령의 여성 문해학습자들은 학령기 학생들에 비해 시험이나 과제가 적고 입시스트레스가 없기 때문에 적당한 학업 스트레스는 오히려 문해교육 프로그램 적응에 도움이 될 수 있으며 자기자비와 문해교육 프로그램 적응은 정적 상관이 있는 것으로 나타났다. 또한 자기자비의 조절효과가 유의한 것으로 나타나 여성 문해학습자들의 문해교육 프로그램 적응을 높이기 위해 자기자비의 역할이 중요함을 확인할 수 있었다. 따라서 자기조절능력을 향상시킬 수 있는 프로그램을 함께 경험할 수 있도록 조력하는 것이 좋은 방법이 될 수 있을 것이다. This study focused on the moderating effect of self compassion to the relationship between female literacy learners’ academic stresses and adjustments in a literacy education program. 247 valid questionnaires from 10 institutions in Gangwon-do were analyzed by one-way ANOVA, correlation and hierarchical regression analysis. Results showed that female literacy learners adapted well to the literacy education program despite academic stresses, due to fewer testing and assignments compared to school-age students, in addition the degree of self-compassion had a statistically significant impact on their program adjustment. Therefore, it is necessary to help female literacy learners to improve their self-control abilities by providing them with appropriate programs.

초친수성 유수분리필터 제조공정에 관한 전과정평가

박성묵 ( Sungmook Park ),김지은 ( Jieun Kim ),염창주 ( Changju Yeom ),이혜진 ( Heyjin Lee ),양성익 ( Sungik Yang ),엄익춘 ( Ig-chun Eom ),김필제 ( Pil-je Kim ),김영훈 ( Younghun Kim ) 한국화학공학회 2016 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.54 No.6

나노기술의 급격한 발전은 다양한 산업응용분야에 기여를 하고 있다. 그러나 나노제품의 증가와 함께, 비의도적인 환경노출이 발생되고 있다. 나노제품에 의한 잠재적인 환경영향은 전과정평가(LCA)를 통해 해석할 수 있다. LCA는 제품의 생산과 폐기에 이르는 전체 공정상의 자원소모 및 배출에 관한 체계적인 해석을 할 수 있다. 본 연구에서는, 나노-TiO₂를 이용한 초친수성 유수분리필터를 제조하는 공정에 관하여 LCA를 수행하였다. 이를 위해 무료로 공개된 TOTAL^TM을 사용하였으며, 6대 환경영향인자인 자원소모, 기후변화, 오존층영향, 산성화, 부영양화, 광화학산화물생성 등의 지표를 해석하였다. 또한 나노-TiO₂를 사용하는 것이 유수분리필터 제조공정에서 벌크-TiO₂를 사용하는 것보다 긍정적으로 환경영향인자에 기여하는 것으로 파악되었다. Rapid growth in nanotechnologies promises novel benefits through the exploitation of their unique indus-trial applications. However, as the production volume of nanomaterials increases, their unintentional exposure to the environment has been occured. Potential impacts of nanoproducts on the environment can be evaluated in the life cycle assessment (LCA). LCA is the systematic analysis of the resource usages and emissions over the life time from the pri-mary resources to the moment of disposal. In this study, we performed LCA for fabrication processes of superhydro-philic oil/water separator using nano-TiO₂. TOTAL^TM freeware was used to analyze for all fabrication processes, and 6- environmental impact factors (resource depletion, climate change, ozone depletion, acidification, eutropication, and pho-tochemical oxidation) were introduced. In addition, the use of nano-TiO₂ in the fabrication of superhydrophilic oil/water separator was actively contributed to the environmental impact factors, compared to the bulk-TiO₂.