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Ji, Yunseong,Cho, Yong il,Jeon, Yukwon,Lee, Chanmin,Park, Dae-Hwan,Shul, Yong-Gun Elsevier BV 2017 Applied Catalysis B Vol.204 No.-
<P><B>Abstract</B></P> <P>Oxygen reduction reaction (ORR) activity and stability of the cathode catalyst are important issues for practical applications, which should be even considered for the materials in high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). To improve these properties, modification of the catalyst electronic structure and finding durable supports can be a good approach. In this study, we synthesized a noble nanofibrous composite electrode which consist of carbon nanotube (CNT)-winded Pt/TiO<SUB>2</SUB> nanofiber (CNT-Pt/TiO<SUB>2</SUB>). Our approach takes advantages of the electrochemical conductivity of CNF as well as better stability from the corrosion resistivity of TiO<SUB>2</SUB> and strong metal-support interaction (SMSI) between the Pt nanoparticles and TiO<SUB>2</SUB> nanofibers for less Pt dissolution. We also found that the Pt electronic state can be changed by an interaction with neighbouring CNT and TiO<SUB>2</SUB>, resulting a decrease of Pt d-band vacancy for enhanced catalytic activity. Furthermore, nanofibrous structure with a unique 3D pore structure provides higher surface area for additional improvements of the mass transfer. These results reveal that the CNT-Pt/TiO<SUB>2</SUB> nanofiber based electrode shows enhanced performance with the maximum power density of 567mWcm<SUP>−2</SUP> compare to commercial Pt/C (461mWcm<SUP>−2</SUP>) with a significant durability at harsh conditions of 120°C and RH 40%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CNT-Pt/TiO<SUB>2</SUB> has exceptional performance and stability at HT-PEMFCs cell test. </LI> <LI> Inorganic–carbon composite shows synergistic effects for good ORR activity. </LI> <LI> CNT and TiO<SUB>2</SUB> cause a charge transfer phenomena offering more electrons to platinum. </LI> <LI> Interconnected nanofibrous catalyst has well organized paths for better transport. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
조윤성(Yunseong Cho),백지웅(Ji-Woong Paik),이준호(Joon-Ho Lee),고요한(Yo Han Ko),조성우(Sung-Woo Cho) 한국전자파학회 2016 한국전자파학회논문지 Vol.27 No.4
안테나 배열을 통한 방향 탐지는 여러 분야에서 활발하게 이루어지고 있는 연구 분야이다. Beamforming, Capon’s method, maximum likelihood(ML), MUSIC 등과 같은 방향 탐지 알고리즘이 대표적이다. 최근 방향 탐지 이론은 압축센싱기법을 이용하여 신호의 희소도를 이용한 방법의 연구가 수행되고 있다. 본 논문에서는 그 중 하나인 신호의 데이터 행렬을 fitting하는 L1-SVD 알고리즘의 성능을 알아보기 위해 MUSIC 알고리즘과 비교하여 장단점을 알아본다. There have been many studies on the direction-of-arrival(DOA) estimation algorithm using antenna arrays. Beamforming, Capon’s method, maximum likelihood, MUSIC algorithms are the main algorithms for the DOA estimation. Recently, compressive sensing -based DOA estimation algorithm exploiting the sparsity of the incident signals has attracted much attention in the signal processing community. In this paper, the performance of the L1-SVD algorithm, which is based on fitting of the data matrix, is compared with that of the MUSIC algorithm.
Sungmin Kim,Yunseong Ji,Young-Jun Sohn,Seunghee Woo,Seok-Hee Park,Namgee Jung,Yun Sik Kang,Sung-Dae Yim 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.2
In this study, we suggest an experimental method to accurately understand the unique performance of membrane electrode assembly (MEA) according to the simulation environment (relative humidity and oxygen concentration) by using a small cell of 3 cm2 and supplying excess gas flow for minimizing reaction environmental gradient during cell operation. Through this, we thoroughly examine the characteristics of the catalysts and composition of electrodes which maximizes the performance of the large-area fuel cell, and also find the composition that minimizes deviations from non-uniformity during large-area operation. Furthermore, we also study the performance characteristics of the MEAs according to the physicochemical properties of catalysts, and microstructures from catalyst and ionomer in detail. The unit cell experiment confirms that different performance characteristics of MEAs during results from the structure of carbon support of each catalyst. In addition, the performance characteristics of MEAs at different operating voltages varies depending on the location of Pt nanoparticles on carbon support caused by its structural characteristics. We believe that this analytic methodology can greatly contribute to the development of optimized electrode structure, which are specialized in various fuel cell application fields, and further commercialization of fuel cell systems.