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이병권 ( Byungkwon Lee ),정세영 ( Seyoung Jeong ),유갑상 ( Gabsang Yoo ),전중남 ( Joongnam Jeon ) 한국정보처리학회 2008 한국정보처리학회 학술대회논문집 Vol.15 No.2
인터넷을 통한 온라인 교육의 활성화로 블랜드형 교육이 이슈로 대두되고 있다. 또한 이러닝 교육을 위한 저작도구 및 하드웨어 장비들이 속속들이 개발되고 활용된다. 이러한 이러닝 교육에 도구 중 전자칠판은 중요 요소이지만 전자칠판과 전자교탁이 분리되어 운용되는 것이 대부분이다. 이로 인한 관리 및 비용 측면에서 단점을 가지고 있다. 본 연구에서는 기존의 전자칠판 및 전자교탁이 따로 분리되어 운용되던 방식을 통합하여 단일형태의 임베디드 교육시스템의 구현을 소개한다. 임베디드 교육시스템은 온라인 교육은 물론 오프라인 교육도 동시에 가능하고, 교수자의 편의를 위하여 USB 기반의 자동 프레젠테이션을 지원하며 학습관리 및 컨턴츠 관리를 위한 소프트웨어를 포함하고 있다.
변형격자계를 이용한 3차원 날개 주변의 비정상 유동 해석
유일용(Ilyong Yoo),이병권(Byungkwon Lee),이승수(Seungsoo Lee) 한국전산유체공학회 2010 한국전산유체공학회지 Vol.15 No.1
Deforming mesh should be used when bodies are deforming or moving relative to each other due to the presence of aerodynamic forces and moments. Also, the flow solver for such a flow problem should satisfy the geometric conservation law to ensure the accuracy of the solutions. In this paper, a RANS(Reynolds Averaged Navier-Stokes) solver including automatic mesh capability using TFI(Transfinite Interpolation) method and GCL is developed and applied to flows induced by oscillating wings with given frequencies. The computations are performed both on deforming meshes and on rigid meshes. The computational results are compared with experimental data, which shows a good agreement.
Kwak, Jong Hwan,He, Yanxia,Yoon, Byungkwon,Koo, Seyoung,Yang, Zhigang,Kang, Eun Ju,Lee, Bong Ho,Han, Seung-Yun,Yoo, Yung Choon,Lee, Kyung Bok,Kim, Jong Seung The Royal Society of Chemistry 2014 Chemical communications Vol.50 No.86
<P>Rhodamine-labelled dieckol (<B>1</B>) synthesized through a click reaction was found to be localized in the endoplasmic reticulum (ER) of RAW 264.7 cells. Anti-inflammatory activity of compound <B>1</B> was considerably greater than that of dieckol itself.</P> <P>Graphic Abstract</P><P>Rhodamine-labelled dieckol localized in the ER of RAW cells. Anti-inflammatory activity of the compound was greater than that of dieckol. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cc04270k'> </P>
Lee, Jooyoung,Sher Shah, Selim Arif,Yoo, Pil J.,Lim, Byungkwon Elsevier 2017 Chemical physics letters Vol.673 No.-
<P>This letter describes an aqueous-phase synthetic route to hydrous ruthenium oxide (RuO2) nanoparticles and their conversion into crystalline ones via a thermal annealing process. Electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were employed to characterize hydrous and crystalline RuO2 nanoparticles. The hydrous RuO2 nanoparticles exhibited higher activity for hydrogen evolution reaction than commercial Pt catalyst, while the crystalline RuO2 nanoparticles showed better performance for oxygen evolution reaction than IrO2 catalyst. With these hydrous and crystalline RuO2 catalysts, we were able to achieve highly efficient overall electrochemical water splitting. (C) 2017 Elsevier B.V. All rights reserved.</P>
Sher Shah, Md. Selim Arif,Lee, Jooyoung,Rauf, Ali,Park, Jong Hyeok,Lim, Byungkwon,Yoo, Pil J. The Royal Society of Chemistry 2018 Nanoscale Vol.10 No.41
<P>Pt, a representative electrocatalyst for the oxygen reduction reaction (ORR), has suffered from high cost and poor stability, and thus it is essential to develop alternative electrocatalyst with a high catalytic activity comparable to Pt. Herein, we propose a rationally designed metal-free electrocatalyst with exposed active sites using an N, P, and S ternary-doped and graphene-incorporated porous carbon foam. We developed a novel template-free synthetic approach wherein the electrostatically-mediated complexation of graphene oxide (GO) with 2-aminothiazole (2AT) and branched polyethylenimine (PEI) in the presence of phytic acid (PA) was first induced, followed by a carbonization process to drive the formation of a three-dimensionally interconnected porous carbon foam. The resulting electrocatalyst exhibited a high pore volume and greatly extended specific surface area along with exposed active sites. Benefiting from these properties, the synthesized ternary-doped carbon foam displayed an outstanding electrocatalytic activity for the oxygen reduction ORR through four-electron transfer pathways. We observed that the remarkably improved ORR performance of the synthesized materials manifested an onset and a half-wave potential, mostly close to those of the commercially available ORR electrocatalyst of 20 wt% Pt/C while securing a greater stability in alkaline media.</P>
Selvam, N. Clament Sagaya,Lee, Jooyoung,Choi, Gwan H.,Oh, Min Jun,Xu, Shiyu,Lim, Byungkwon,Yoo, Pil J. The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.48
<P>The development of efficient and stable bifunctional catalysts that outperform noble metal catalysts is a crucial task and an ongoing challenge for sustainable water electrolysis. In this work, large-size-exfoliated MXene sheets render a flat and flexible platform for the decoration of Co(OH)F, CoP and Co7Se8, allowing them to exhibit high electrocatalytic performances; thanks to the maximized surface area and conductivity. CoP/MXene shows enhanced oxygen evolution reaction (OER) activity, with substantially lower overpotential (<I>η</I> = 230 mV) at 10 mA cm<SUP>−2</SUP> compared to those of IrO2 (300 mV). Furthermore, a hybrid bifunctional electrode (CoP/MXene//CoP/MXene) exhibits highly stable and efficient overall water splitting performance (1.56 V@10 mA cm<SUP>−2</SUP>) as compared to the benchmark electrode couple IrO2/C//Pt/C (1.62 V@10 mA cm<SUP>−2</SUP>) in alkaline solution. Furthermore, we elucidate the oxidation process of the anion components (P and Se) of the hybrid catalysts under OER conditions and verify their significant influence on the activity and stability. Notably, the surface oxidation of CoP/MXene results in a POx-enriched Co-OOH/CoP/MXene hybrid, which enables retention of consistent activity and stability. On the other hand, SeOx deposition on the Co-OOH/Co7Se8/MXene surface significantly deteriorates the activity and stability of the catalyst. These results not only highlight the insight on the correlation between oxidized anion species and the intrinsic activity of hybridized electrocatalysts but also impart the systematic synthetic design of MXene-supported catalysts with high water-splitting efficiency.</P>
Sher Shah, Md. Selim Arif,Lee, Jooyoung,Park, A. Reum,Choi, Youngjin,Kim, Woo-Jae,Park, Juhyun,Chung, Chan-Hwa,Kim, Jaeyun,Lim, Byungkwon,Yoo, Pil J. Elsevier 2017 ELECTROCHIMICA ACTA Vol.224 No.-
<P><B>Abstract</B></P> <P>SnO<SUB>2</SUB> is a well-studied anode material for lithium ion batteries (LIBs). However, it undergoes severe capacity fading because of a large volume change (∼300%) during cycling. Composites of SnO<SUB>2</SUB> with electro-conductive graphene would deliver improved capacity and rate performance. Nevertheless, achieving the theoretical capacity of SnO<SUB>2</SUB> is still elusive, mainly because of disintegration of the active material from graphene and severe aggregation of SnO<SUB>2</SUB>, or Sn nanoparticles produced upon cycling. To surmount these limitations, in this work, nanocomposites containing ultra-fine sized SnO<SUB>2</SUB> nanoparticles (UFSN) with reduced graphene oxide and amorphous carbon were synthesized in a single step at low temperature and environmentally benign way, in which ascorbic acid was employed as the carbon source and reducing agent. UFSN could decrease the lithium ion diffusion path length. As a result of effective buffering effect afforded by the mesoporous structure against volume change and improved lithium ion diffusivity, the ternary nanocomposite achieves ultra-high capacity of 1245mAhg<SUP>−1</SUP> after 210 cycles at 100mAg<SUP>−1</SUP> and excellent cycling stability. Since the proposed approach is facile, straightforward, and highly reproducible, it is anticipated that this system would be a potential alternative to the conventional graphite anode for LIBs.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>