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Ultrasmall PtSn alloy catalyst for ethanol electro-oxidation reaction
Kwak, Da-Hee,Lee, Young-Woo,Han, Sang-Beom,Hwang, Eui-Tak,Park, Han-Chul,Kim, Min-Cheol,Park, Kyung-Won Elsevier 2015 Journal of Power Sources Vol.275 No.-
<P><B>Abstract</B></P> <P>To improve the electrocatalytic properties for an ethanol electro-oxidation reaction, modifications of Pt nanocrystallites have been used by alloying with other elements such as Ru, Sn, and Au. Here we demonstrate carbon supported Pt<SUB>3</SUB>Sn alloy electrocatalyst (Pt<SUB>3</SUB>Sn/C) synthesized using a thermal-decomposition method. The PtSn/C prepared by the present synthetic process shows a homogeneous distribution of ultrasmall alloy nanoparticles (∼2.5 nm) in the presence of Pt and Sn metallic states. At 0.45 V, the Pt<SUB>3</SUB>Sn/C (0.35 mA cm<SUP>−2</SUP>) exhibits much higher current density as compared with Pt/C (0.13 mA cm<SUP>−2</SUP>). In an electrochemical stability test, the Pt<SUB>3</SUB>Sn/C supported quite high current density and thus showed 3% current reduction after the stability test.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pt<SUB>3</SUB>Sn nanoparticles with an ultrasmall size of 2.5 nm were synthesized. </LI> <LI> Pt<SUB>3</SUB>Sn nanoparticles showed improved electrocatalytic activity and stability. </LI> <LI> The improved activity may be attributed to a well-defined alloy formation. </LI> </UL> </P>
EMTP 선로모델이 과전압 해석결과에 미치는 영향에 관한 연구
김경탁(Kyung-Tak Kim),곽주식(Joo-Sik Kwak),권동진(Dong-Jin Kweon),구교선(Kyo-Sun Koo),우정욱(Jung-Wook Woo) 한국조명·전기설비학회 2010 조명·전기설비학회논문지 Vol.24 No.10
There are several overvoltages by abnormal conditions in power system. We need to calculate these ovevoltages for the insulation design and the fault analysis. For these calculations, we used EMTP(Electro-magnetic Transients Program). During EMTP calculations, the accurate modelling of the equipments is very important for analysis results. In this paper, we considered the effects of the modelling condition's changes for transmission line within EMTP modelling cases of overvoltage analysis. Specially, we considered CB closing cases of 765[㎸] system. So, we had changed the calculation frequencies of Line Constants, which is used for CB closing cases. In addition, we compared the calculation result and the measured result.
곽주식(Joosik Kwak),우정욱(Jung-Wook Woo),김경탁(Kyung Tak,Kim),구교선(Kyosun Koo),권동진(Dong-jin Kweon) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
As most faults in transmission system are caused by lightning, electric power utility companies have been trying to get solutions. Lightning information itself is the one among the them. This paper describes statistical analysis results of lightning activities in 2009 observed by KLDNet, which is a lightning location and data service system being operated by KEPCO.
곽주식(Joosik Kwak),김경탁(Kyung-Tak Kim),구교선(Kyosun Koo) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.10
This paper presents lightning overvoltage analysis results of 170㎸ switch gear in gas insulated substation. The overvoltage is originated from lightning stroke to transmission line interconnected. To calculate the overvoltage in transmission line and substation, EMTP model which include distributed transmission line model of BUS, circuit breaker was built.
Synthesis of hollow carbon nanostructures as a non-precious catalyst for oxygen reduction reaction
Lee, Seul,Kwak, Da-Hee,Han, Sang-Beom,Hwang, Eui-Tak,Kim, Min-Cheol,Lee, Jin-Yeon,Lee, Young-Woo,Park, Kyung-Won Elsevier 2016 ELECTROCHIMICA ACTA Vol.191 No.-
<P><B>Abstract</B></P> <P>Carbon-based nanostructures as a non-precious catalyst for oxygen reduction reaction (ORR) exhibit excellent electrocatalytic activities due to high specific surface areas and favorable active sites supported by the doped transition metals and nitrogen species. We synthesize the metal-nitrogen doped carbon nanostructures (MPc-C, M=Fe,Co) by using a template method in the presence of metal phthalocyanine including FePc, CoPc, and FeCoPc as metal and nitrogen as well as carbon sources. The as-prepared carbon nanostructures show a high specific surface area, porous structure, and metal-nitrogen dopants, as observed by field-emission scanning electron microscopy (FE-SEM), field-emission transmission electron microscopy (FE-TEM), X-ray photo-electron spectroscopy (XPS), and nitrogen sorption measurement. Especially, among the doped carbon nanostructures, FeCoPc-C exhibits superior ORR electrocatalytic properties in an alkaline medium: an electron transfer number close to 4, high half-wave potential, improved electrochemical stability, and methanol tolerance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We synthesized the metal-nitrogen doped carbon nanostructures using a facile method. </LI> <LI> The nanostructures consisted of a high specific surface area and porous structure. </LI> <LI> The nanostructures exhibited well-doped transition metal and nitrogen species. </LI> <LI> The nanostructures showed excellent electrocatalytic activities in ORR. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
낙뢰감지기 주변의 전자기 노이즈 측정 및 스펙트럼 분석
곽주식(Joosik Kwak),우정욱(Jung-Wook Woo),김경탁(Kyung Tak),구교선(Kim Kyosun Koo),안광훈(Gwanghoon Ahn) 대한전기학회 2010 대한전기학회 학술대회 논문집 Vol.2010 No.7
As lightning location system detects electric field or magnetic field emitted from distant lightning source, the performance of lightning locating system is dependent to the electro-magnetic interference around sensor. Before and after the installation of lightning sensor, the interference need to be kept under acceptable level. This paper describes a measurement and analysis of noise spectrum done at sensor sites of KLDNet.