The Role of Ruthenium on Carbon-Supported PtRu Catalysts for Electrocatalytic Glycerol Oxidation under Acidic Conditions

Kim, Youngmin,Kim, Hyun Woo,Lee, Seonhwa,Han, Jisu,Lee, Daewon,Kim, Jeong-Rang,Kim, Tae-Wan,Kim, Chul-Ung,Jeong, Soon-Yong,Chae, Ho-Jeong,Kim, Beom-Sik,Chang, Hyunju,Kim, Won Bae,Choi, Sung Mook,Kim, Wiley Blackwell (John Wiley Sons) 2017 ChemCatChem Vol.9 No.9

α-Lipoic acid attenuates vascular calcification <i>via</i> reversal of mitochondrial function and restoration of Gas6/Axl/Akt survival pathway

Kim, Hyunsoo,Kim, Han-Jong,Lee, Kyunghee,Kim, Jin-Man,Kim, Hee Sun,Kim, Jae-Ryong,Ha, Chae-Myeong,Choi, Young-Keun,Lee, Sun Joo,Kim, Joon-Young,Harris, Robert A,Jeong, Daewon,Lee, In-Kyu Blackwell Publishing Ltd 2012 Journal of cellular and molecular medicine Vol.16 No.2

<P><B>Abstract</B></P><P>Vascular calcification is prevalent in patients with chronic kidney disease and leads to increased cardiovascular morbidity and mortality. Although several reports have implicated mitochondrial dysfunction in cardiovascular disease and chronic kidney disease, little is known about the potential role of mitochondrial dysfunction in the process of vascular calcification. This study investigated the effect of α-lipoic acid (ALA), a naturally occurring antioxidant that improves mitochondrial function, on vascular calcification <I>in vitro</I> and <I>in vivo</I>. Calcifying vascular smooth muscle cells (VSMCs) treated with inorganic phosphate (Pi) exhibited mitochondrial dysfunction, as demonstrated by decreased mitochondrial membrane potential and ATP production, the disruption of mitochondrial structural integrity and concurrently increased production of reactive oxygen species. These Pi-induced functional and structural mitochondrial defects were accompanied by mitochondria-dependent apoptotic events, including release of cytochrome <I>c</I> from the mitochondria into the cytosol, subsequent activation of caspase-9 and -3, and chromosomal DNA fragmentation. Intriguingly, ALA blocked the Pi-induced VSMC apoptosis and calcification by recovery of mitochondrial function and intracellular redox status. Moreover, ALA inhibited Pi-induced down-regulation of cell survival signals through the binding of growth arrest-specific gene 6 (Gas6) to its cognate receptor Axl and subsequent Akt activation, resulting in increased survival and decreased apoptosis. Finally, ALA significantly ameliorated vitamin D<SUB>3</SUB>-induced aortic calcification and mitochondrial damage in mice. Collectively, the findings suggest ALA attenuates vascular calcification by inhibiting VSMC apoptosis through two distinct mechanisms; preservation of mitochondrial function <I>via</I> its antioxidant potential and restoration of the Gas6/Axl/Akt survival pathway.</P>

Quench Detection Method of HTS Model Coil Using a Series-Type Thermocouple

Daewon Kim,Jin-Geun Kim,A-Rong Kim,Minwon Park,In-Keun Yu,Ki-Deok Sim,Seockho Kim,Jeonwook Cho,Myung-Hwan Sohn IEEE 2011 IEEE transactions on applied superconductivity Vol.21 No.3

<P>This paper proposes a quench detection method applied to a HTS coil and also discusses the results of tests on an HTS BSCCO wire and an HTS YBCO coil. A series-type thermocouple was fabricated to detect quench, where several thermocouples were welded in series. As the series-type thermocouple has many points of detection, variation in temperature was detected at each point by using thermo-electromotive force. The feasibility of the proposed method was investigated through the quench detection tests on the YBCO coil. This method has advantages such as a simple structure and cost effectiveness and also protects the HTS coil by detecting partial quench and its propagation.</P>

High-performance nanopattern triboelectric generator by block copolymer lithography

Kim, Daewon,Jeon, Seung-Bae,Kim, Ju Young,Seol, Myeong-Lok,Kim, Sang Ouk,Choi, Yang-Kyu Elsevier 2015 Nano energy Vol.12 No.-

<P><B>Abstract</B></P> <P>Large-area nanopatterning is introduced on a flexible gold substrate by block copolymer (BCP) lithography. We fabricate ultrahigh power energy harvesting nanogenerators based on contact-electrification principle exploiting the effective contact area enhancement by block copolymer lithography. Owing to the facile and effective surface area enhancement by BCP nanopatterning, significant enhancement of triboelectric charge induction is attained. Output currents from TENG increased at least 16 times after BCP nanopatterning. This nanogenerator can generate remarkably high output voltage and current, which can directly light up 504 serially connected LEDs. The resultant nanogenerator attains the maximum instantaneous current of 1.6mA and output power of 93.2W/m<SUP>2</SUP>. Electrical energy generated by single cycle of impact force is 0.54mJ, and the average electrical energy is 114.89mW. Those values indicate one of the highest device performance ever reported for the TENGs based on contact-separation mode thus far.</P> <P><B>highlights</B></P> <P> <UL> <LI> Large-area nanopatterning is introduced on a flexible Au substrate by block copolymer lithography. </LI> <LI> We fabricate ultrahigh power energy harvesting nanogenerators based on contact-electrification principle exploiting the effective contact area enhancement by block copolymer lithography. </LI> <LI> This nanogenerator can generate remarkably high output voltage and current, which can directly light up 504 serially connected multicolored LEDs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Selective inhibition of RANK blocks osteoclast maturation and function and prevents bone loss in mice

Kim, Hyunsoo,Choi, Han Kyoung,Shin, Ji Hye,Kim, Kyung Hee,Huh, Ji Young,Lee, Seung Ah,Ko, Chang-Yong,Kim, Han-Sung,Shin, Hong-In,Lee, Hwa Jeong,Jeong, Daewon,Kim, Nacksung,Choi, Yongwon,Lee, Soo Young American Society for Clinical Investigation 2009 The Journal of clinical investigation Vol.119 No.4

<P>Regulation of the formation and function of bone-resorbing osteoclasts (OCs) is a key to understanding the pathogenesis of skeletal disorders. Gene-targeting studies have shown that the RANK signaling pathway plays a critical role in OC differentiation and function. Although pharmaceutical blockade of RANK may be a viable strategy for preventing bone destruction, RANK is implicated in multiple biological processes. Recently, a cytoplasmic motif of RANK was identified that may be specifically involved in OC differentiation. Here, we developed a cell-permeable inhibitor termed the RANK receptor inhibitor (RRI), which targets this motif. The RRI peptide blocked RANKL-induced OC formation from murine bone marrow-derived macrophages. Furthermore, RRI inhibited the resorptive function of OCs and induced OC apoptosis. Treatment with the peptide impaired downstream signaling of RANK linked to Vav3, Rac1, and Cdc42 and resulted in disruptions of the actin cytoskeleton in differentiated OCs. In addition, RRI blocked inflammation-induced bone destruction and protected against ovariectomy-induced bone loss in mice. These data may be useful in the development of selective therapeutic agents for the treatment of osteoporosis and other bone diseases.</P>

Enhanced electrochemical oxygen reduction reaction performance with Pt nanocluster catalysts supported on microporous graphene-like 3D carbon

Kim, Youngmin,Lee, Daewon,Kwon, Yonghyun,Kim, Tae-Wan,Kim, Kyoungsoo,Kim, Hyung Ju Elsevier 2019 Journal of Electroanalytical Chemistry Vol.838 No.-

<P><B>Abstract</B></P> <P>Here we report an efficient catalyst design strategy to develop high performance Pt-based electrocatalysts for oxygen reduction reaction (ORR). Finely-dispersed Pt nanoclusters supported on microporous graphene-like 3D carbon (Pt/MGTC) having a Pt size of <I>ca.</I> 1.3nm were synthesized by zeolite template-based carbon synthesis and subsequent Pt impregnation. The Pt/MGTC catalyst demonstrated about 2 times higher ORR activity than that of commercial Pt/C. In addition, the Pt/MGTC showed relatively stable ORR performance, maintaining an activity higher than that of Pt/C. This performance enhancement of electrocatalytic ORR on Pt/MGTC was attributed to the significant increase of Pt active sites and the efficient charge transport in Pt/MGTC.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly-dispersed Pt nanoclusters supported on microporous graphene-like 3D carbon (Pt/MGTC) were synthesized. </LI> <LI> The Pt/MGTC led to improved catalytic performances for electrochemical oxygen reduction reaction. </LI> <LI> This performance enhancement was attributed to many Pt active sites and efficient charge transport in Pt/MGTC. </LI> </UL> </P>

네이버 뉴스스탠드 도입 이후 뉴스 웹사이트 네트워크 구조 분석

김대원(Kim, Daewon),김수원(Kim, Suwon),김성철(Kim, Seongcheol) 사이버커뮤니케이션학회 2014 사이버 커뮤니케이션 학보 Vol.31 No.4

본 연구는 네이버의 뉴스스탠드 도입 이후의 온라인 뉴스 웹사이트 네트워크 구조를 분석했다. 국내 온라인 미디어 생태계의 정점에 위치한 네이버의 뉴스유통 체계 변화는 뉴스 웹사이트 네트워크 구조의 틀 자체를 흔들어, 새로운 질서를 형성했을 것이라고 판단했기 때문이다. 연구는 뉴스 웹사이트의 유출입을 사회연결망 분석(Social network analysis)을 통해 고찰하는 방식으로 이뤄졌다. 연구 결과, 온라인 뉴스 웹사이트 네트워크 내에서 포털, 그 중에서도 네이버와 다음은 유입과 유출 모든 측면에서 강력한 중심성을 확보하고 있었다. 또한, 설립 2년 밖에 안 된 포털 ‘줌’이 기존 유력 언론사와 비견될 영향력을 확보한 것으로 분석됐다. 이는 온라인상에서 콘텐츠 출처에 대해 무차별하며 여러 매체의 뉴스를 한 데 묶어서 제공하는 백화점식 공급 방식을 선호하는 국내 온라인 뉴스 소비자의 성향을 보여준다. This research studied into the structure of online news website after the launch of News stand, which is Naver’s main platform for mediating news between customers and news providers. This is because the new platform has changed radically the online news website structure. This paper employed social network analysis as a methodology. This study found out that Naver and Daum have powerful centrality on the aspect of inflow and outflow. Zum, which is an only two-year old portal company, has as high status in the network as influential media. These results show two characteristics of Korean news-customers; the first one is that they are indifferent to the source of contents, the second one is that the customers prefers platform system proving multiple news from various media. Some economic newspapers have a good position in the news website network. While specialized media covering information technology or soccer also high status in the media ecosystem network, local newspapers are alienated. Facebook seems to have a structural status like Chosun Ilbo and Dong-A Ilbo in Korean online news website network.

Quench detection method using a series type thermocouple

김대원(Daewon Kim),김진근(Jin-Geun Kim),김아롱(A-Rong Kim),박민원(Minwon Park),유인근(In-Keun Yu),심기덕(Ki-Deok Sim),김석호(Seockho Kim),조전욱(Jeonwook Cho) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7

This paper proposed a quench detection method applied to the HTS (High Temperature Superconducting) wire and the results of the test on a HTS BSCCO (Bismuth Strontium Calcium Copper Oxide) wire were discussed. A series type thermocouple was fabricated for the quench detection. Several thermocouples were welded in series connection, so the series type thermocouple has many detecting points. The temperature variation was detected at each point by using the thermo electromotive force. The feasibility of the proposed method was investigated through the quench detection tests for HTS BSCCO wire. Also, this method has several advantages such as simple structure and cost effectiveness.

네이버 지배구조에 대한 사례연구

김대원(Daewon Kim),김도경(Dokyung Kim),이홍규(Hongkyu Lee),김성철(Seongcheol Kim) 한국방송학회 2015 한국방송학보 Vol.29 No.1

OTT 서비스 도입 전후 해외 방송사업자의 콘텐츠 전략에 대한 비교 분석

김대원(Daewon Kim),김수원(Suwon Kim),김성철(Seongcheol Kim) 한국정보사회학회 2016 정보사회와 미디어 Vol.17 No.2

본 연구에서는 OTT(over the top) 서비스 도입 전후에 해외 방송사업자의 전략 변화양상을 비교분석했다. 독일, 미국, 영국, 일본, 중국, 프랑스까지 6개 방송시장 상위 국가의 유관 기업 16개가 연구 대상으로 선택됐다. OTT 서비스 전략의 도입 전후를 기준으로 각 사업자의 전략에 대한 네트워크 분석 결과를 비교하는 방식으로 연구는 진행됐다. 연구 결과, 방송사업자의 콘텐츠 전략 네트워크는 OTT 서비스 전략이 도입된 이후에 보다 촘촘해졌고, 네트워크 내 각 전략 간의 연결성은 제고됐다. 연결정도 중심성 측면에서 OTT 서비스 전략 도입 이전에 네트워크 중앙에는 전용망 관련 전략이 배치됐고, 온라인 기반의 전략은 상대적으로 네트워크 내에서 변방에 소재했다. 그러나 OTT 서비스가 전략 구조에 포함된 이후, 동영상 콘텐츠 전략 간 위상의 강도가 거의 동등해졌다. 전략 간 중개자로서의 위상을 나타내는 매개 중심성 측면에서도 특정 전략 편중 현상이 약화됐다. 콘텐츠에서는 비선형, 플랫폼과 단말기에서 온라인 기반의 범용망·PC·모바일이 OTT 서비스 전략이 채택된 이후에는 방송사업자의 콘텐츠 전략 네트워크에서 수위의 위상을 점유한 것으로 파악됐다. This study conducted a comparative analysis on contents strategies of foreign video service providers before and after the introduction of over-the-top (OTT) service. 16 video service providers from six countries, i.e. Germany, United States, England, Japan, China and France, were selected. The network structures of their strategies were drawn and compared before and after the adoption of OTT service, using network analysis method. The result shows that a network-structure after the introduction of OTT became denser, and the relationships between each strategy became closer in the network structure. In terms of the degree centrality and betweenness centrality, most strategies had remarkable differences. The highest tier in the network after the introduction of OTT was occupied by online based strategies such as non-linear contents, personal computers, and mobile devices.