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Morphology control of noble metal catalysts from planar to dendritic shapes by galvanic displacement
Baek, Seungyeon,Kim, Kwang Hwan,Kim, Myung Jun,Kim, Jae Jeong Elsevier 2017 Applied Catalysis B Vol.217 No.-
<P><B>Abstract</B></P> <P>Noble metal electrocatalysts can simply be prepared via galvanic displacement method on a sacrificial substrate, which is advantageous for preparing a uniform and thin catalyst layer. However, it is difficult to control the morphology of deposited metals via galvanic displacement, therefore, there is a limitation to increase the surface area of electrocatalysts. In this study, we demonstrate galvanic displacement for controlling the morphology of Pd, Pt, and Au from planar to whisker shapes by manipulating the dissolution rate of the sacrificial Cu substrate and the mass transport of noble metal ions. The acceleration of the dissolution of sacrificial substrate increases the reduction rate of noble metal, which develops a steep concentration gradient of noble metal ions near the surface of substrate. This induces the selective deposition of noble metal to form a whisker instead of smooth film. To verify the advantage of whisker-type catalysts, the ethanol oxidation with Pd is investigated. Whisker-type Pd shows 21 times higher electrocatalytic performance than planar Pd due to larger surface area. Therefore, it can be suggested that whisker-type catalysts simply prepared by galvanic displacement is applicable for various electrocatalytic reactions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pd, Pt, and Au whisker were obtained via one-step galvanic displacement. </LI> <LI> The mechanism of whisker formation was investigated by electrochemical measurements. </LI> <LI> The steep concentration gradient of noble metal ions resulted in the formation of whisker. </LI> <LI> The concentration gradient was controlled by the rates of oxidation and mass transport. </LI> <LI> Pd whisker showed enhanced ethanol oxidation activity compared to planar catalyst. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Baek, Seungyeon,Kim, Kwang Hwan,Choi, Insoo,Kwon, Oh Joong,Kim, Jae Jeong Elsevier 2018 Chemical engineering journal Vol.335 No.-
<P><B>Abstract</B></P> <P>The intrinsic solubility of a gaseous substance and its dissolution rate play important roles in carrying out electrochemical reaction of gaseous reactant, in addition to the activity of catalyst. We tried to increase the solubility and dissolution rate of N<SUB>2</SUB>O by introducing Taylor vortices using a Couette-Taylor flow (CTF) mixer and investigated how the enhanced N<SUB>2</SUB>O dissolution affected the electrochemical reduction of N<SUB>2</SUB>O. The solubility and saturation time were estimated by electrochemical measurement of N<SUB>2</SUB>O concentration in the electrolyte solution. It was found that the Taylor vortices could not only increase the solubility of N<SUB>2</SUB>O but also reduce the time required to saturate the electrolyte with N<SUB>2</SUB>O. Furthermore, a high N<SUB>2</SUB>O conversion rate via electrochemical reduction was obtained with the introduction of Taylor vortices. We proved that an enhanced solubility and dissolution rate of the gaseous substance could be attained by using a CTF mixer as one of the alternatives for enhancing the electrochemical reaction of a gaseous substance in an aqueous electrolyte solution.</P>
시스템과 생활세계의 충돌과 비제도권 정치운동 : 성미산 운동 사례를 중심으로
백영민 ( YoungMin Baek ),원승연 ( Seungyeon Won ) 연세대학교 사회과학연구소 2017 社會科學論集 Vol.48 No.2
본 논문에서는 성미산 마을운동을 분석사례로 지역기반 정치참여가 어떤 방식으로 이루어지며, 지역기반 정치참여는 투표 참여와 같은 기존의 제도권 정치참여나 공동체 활동과 같은 비제도적 시민참여와 어떻게 다른 동원 메커니즘을 갖는지 살펴보았다. 시스템과 생활세계가 충돌하면서 생기는 갈등에 대한 하버마스의 이론틀을 기반으로 본 논문에서는 지역기반 정치참여를 지역이라는 중앙정부의 합리성으로부터 생활세계의 합리성을 방어하기 위한 형태의 비제도적 정치운동(non-institutional political movement)으로 파악하였다. 비제도적 정치운동에 대한 동원 메커니즘를 파악하기 위해 본 논문에서는 정치체제에 대한 불신과 동료시민에 대한 신뢰의 역할에 초점을 맞추었다. 성미산 거주자에 대한 설문조사결과 비제도적 정치운동인 성미산 운동에 참여한 시민들은 정치체제에 대해서는 불신하지만(시스템에 대한 불신) 동료시민에 대해서는 신뢰하는(생활세계에 대한 신뢰) 모습을 보였다. 비제도적 정치운동과 제도적 정치참여 비제도적 시민참여에 미치는 정치불신과 동료시민신뢰의 효과를 비교한 결과를 기반으로 지역기반 정치운동이 갖는 이론적, 시대적 함의도 같이 논의하였다. This study investigates the mobilization mechanism of the community-based movement and how it differs from conventional, non-institutional civic participation and institutional political participation. Relying on the Habermasian framework on the conflict between modern rationality in the system and values of life-worlds and participation literature, this study approaches the community-based movement as a defense mechanism against government intrusion into citizens’ life-worlds, defining citizens’ participation in these movements as non-institutional political participation. Regarding the mobilization mechanism, this study focuses on the roles of interpersonal trust - vital for collective behaviors - and political distrust as preconditions to combat governmental intrusion into their life-worlds. Analyses of survey responses participants and nonparticipants in these movements revealed several interesting findings and democratic implications. Based on the findings, this study discusses the democratic implications of community-based movements in an age seeking an alternative modernity latent in life-worlds.
Solid-Phase Synthesis of 1,3,7,8-Tetrasubstituted Xanthine Derivatives on Traceless Solid Support
Lee, Doohyun,Lee, Seungyeon,Liu, Kwang-Hyeon,Bae, Jong-Sup,Baek, Dong Jae,Lee, Taeho American Chemical Society 2016 ACS Combinatorial Science Vol.18 No.1
<P>Traceless solid-phase synthesis of 1,3,7,8-tetrasubstituted xanthine (1,3,7,8-tetrasubstituted 1H-purine-2,6(3H,7H)-dione) derivatives has been developed. The solid-phase synthetic route began on a solid supported N'-cyano-N-substituted carbamimidothioate, which was prepared from cyanamide, isothiocyanate, and Merrifield resin. After N-alkylation of carbamimidothioate resin with ethyl 2-bromoacetate, an imidazole ring is introduced by Thorpe-Ziegler-type cyclization. The resulting imidazole resin is converted to 1,3,7-trisubstituted xanthine resin using sequential reactions, such as Lewis acid-catalyzed urea formation, pyrimidine ring cyclization, and N-alkylation. After oxidation of sulfides to sulfones, traceless cleavage with amine or thiol nucleophiles afforded the desired 1,3,7,8-tetrasubstituted xanthines in good purities and overall yields (eight-steps; 36 examples). This efficient solid-phase synthesis enables the incorporation of four diversity points into the preparation of the 1,3,7,8-tetrasubstituted xanthines.</P>
서울시 공동주택의 입면색채 및 이미지 특성에 관한 연구
정찬웅(Chanung Jeong),양창석(Changseok Yang),이승연(Seungyeon Lee),고정림(Jeonglim Ko),백향(Baek Hyang) 한국색채학회 2019 한국색채학회 학술대회 Vol.2019 No.12
근래의 입면색채계획은 과거 원색사용으로부터 벗어나려 했던 소극적 색채계획의 개념을 탈피하여 색채계획의 원칙을 확대 해석하고, 시대적 흐름을 반영하여 세련되고, 다채로운 계획방법이 제안되고 있다. 이에 근래의 공동주택 이미지는 주변경관을 배려하고 지역의 고유성을 반영하여야 한다는 의식과, 매력적인 도시이미지 형성을 위해 지역의 특수성을 반영하여야 한다는 의식이 상충되면서, 경관계획에 대한 방향성이 일괄적 관점으로 해석되지 않는다. 본 연구는 근래의 서울시 6개소 공동주택의 입면을 대상으로 이미지 평가를 실시하였으며, 향후 도시 이미지의 방향성을 인지하는데 그 목적이 있다. 평가 결과 공동주택 이미지에 대한 요인축은 「조화로운·정돈된」, 「독특한·리듬감있는」, 「도시적인·세련된」, 「개방감있는」의 4요인축으로 분류되었으며, 자극적이지 않은 배색 배열과 비일률적 패턴이 평가자에게 편안함과 안정감을 주는 것으로 나타났다. 또한 상대적으로 고채도의 강조색을 사용한 공동주택은 낮게 평가되었으며, 고명도·저채도의 주조색, 중명도·저채도의 보조색을 적용한 공동주택은 높게 평가되었다.
Ethylenediamine Promotes Cu Nanowire Growth by Inhibiting Oxidation of Cu(111)
Kim, Myung Jun,Flowers, Patrick F.,Stewart, Ian E.,Ye, Shengrong,Baek, Seungyeon,Kim, Jae Jeong,Wiley, Benjamin J. American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.1
<P>The synthesis of metal nanostructures usually requires a capping agent that is generally thought to cause anisotropic growth by blocking the addition of atoms to specific crystal facets. This work uses a series of electrochemical measurements with a quartz crystal microbalance and single-crystal electrodes to elucidate the facet-selective chemistry occurring in the synthesis of Cu nanowires. Contrary to prevailing hypotheses, ethylenediamine, a so-called capping agent in the synthesis of Cu nanowires, causes anisotropic growth by increasing the rate of atomic addition to (111) facets at the end of a growing nanowire relative to (100) facets on the sides of a nanowire. Ethylenediamine increases the reduction rate of Cu(OH)(2)(-) on a Cu(111) surface relative to Cu(100) by selectively inhibiting the formation of Cu oxide on Cu(111). This work demonstrates how studying facet-selective electrochemistry can improve the understanding of the processes by which atoms assemble to form anisotropic metal nanostructures.</P>
정기범(Chung KiBeom),이강원(Lee KangWon),홍다경(Hong DaKyoung),백승연(Baek SeungYeon),김우중(Kim Woojoong),김은한(Kim EunHan) 한국정보기술학회 2022 Proceedings of KIIT Conference Vol.2022 No.6
본 논문에서는 Open Map API 중 Naver Map API를 이용하여 사용자의 요구에 따른 놀거리 코스 리스트를 추천해주거나 산책을 위한 코스 리스트를 추천하는 애플리케이션 서비스에 관해 기술한다. 또한 사용자가 알고 있는 놀거리, 산책코스를 직접 등록할 수 있고 해당 코스를 다른 유저들이 이용할 수 있다. 그리고 모든 코스리스트에는 사용자가 이용하고 남긴 리뷰들이 있기 때문에 코스 리스트의 랭킹을 확인해 효율적인 코스 선택을 제공한다. This paper describes an application service that recommends acourse list for entertainment or a course list for a walk according to a user’srequest using the Naver Map API among the Open Map APIs. In addition, users canregister their own entertainment and walking courses and other users can usethe courses. And since all course lists have reviews that users have used andleft behind, it provides efficient course selection through checking theranking of the course list.