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Convergence of the Sport Tourism as a Leisure Culture
( Sunghun Choi ) 한국체육학회 2016 국제스포츠과학 학술대회 Vol.2016 No.1
Purpose: This study is to research in Sport Tourism Studies as leisure culture, and also to suggest the future direction of this area in the perspective of convergence. Method: The methods used in the study are the literature analysis which is the method of using the Electronic Journal Database System of the National Assembly Library (http://www.nanet.go.kr), the Korean Studies Information Service (http://www.kstudy.com ), and the Online Library of the University of Brighton (http://libguides.brighton.ac.uk). Result: Firstly, there needs to be a conceptual shift in our thinking about this area with a new approach to the convergent concept of Sport Tourism, rather than considering each individual area separately. A convergent sport tourism model that is suggested in this study corresponds well with the notion of Sport Tourism. Secondly, as leisure culture is an expanded model of a modified convergent sport tourism which includes culture and art, researching on this area also helps to understand the nature of leisure and its behaviour as well as leisure industry. Thirdly, we are desperately in need of more conferences and seminars prior to hosting the 2018 Winter Olympics in Pyeongchang, and we also keep up with the latest relevant studies in the same level of world standard. It also should be encouraged to research on the related subjects such as Globalization, Nationalism and Identity, Leisure Constraint Negotiation Strategies, Serious leisure, Urban Regeneration, Sustainability, and Active Sport Tourism. Finally, academic courses in Sport Tourism should be offered widely in universities for a degree and even a master’s degree. To make this happen, we need to design a new syllabus and develop the relevant textbook contents in a diverse perspective. Conclusion: The Ministry of Culture, Sports and Tourism should take the head in supporting the convergence of Sport and Tourism, and Culture and Arts to maximize the benefits of Sport Tourism on each level of world/nation/local. And also the articles of sport tourism for convergence should be reflected in the National Assembly, Budget, Legislation, Publication, and Reports. English Academic journals should be established to lead our research on Active Sport Tourism to success in the perspective of convergence, by providing wider publicity of our events and functions to the world. It would be also helpful with either holding of a number of international conferences or event hosting.
Choi, Sunghun,Jung, Dae Soo,Choi, Jang Wook American Chemical Society 2014 NANO LETTERS Vol.14 No.12
<P>A variety of silicon (Si) nanostructures and their complex composites have been lately introduced in the lithium ion battery community to address the large volume changes of Si anodes during their repeated charge–discharge cycles. Nevertheless, for large-scale manufacturing it is more desirable to use commercial Si nanoparticles with simple surface coating. Most conductive coating materials, however, do not accommodate the volume expansion of the inner Si active phases and resultantly fracture during cycling. To overcome this chronic limitation, herein, we report silicon oxycarbide (SiOC) glass as a new coating material for Si nanoparticle anodes. The SiOC glass phase can expand to some extent due to its active nature in reacting with Li ions and can therefore accommodate the volume changes of the inner Si nanoparticles without disintegration or fracture. The SiOC glass also grows in the form of nanocluster to bridge Si nanoparticles, thereby contributing to the structural integrity of secondary particles during cycling. On the basis of these combined effects, the SiOC-coated Si nanoparticles reach a high reversible capacity of 2093 mAh g<SUP>–1</SUP> with 92% capacity retention after 200 cycles. Furthermore, the coating and subsequent secondary particle formation were produced by high-speed spray pyrolysis based on a single precursor solution.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2014/nalefd.2014.14.issue-12/nl503620z/production/images/medium/nl-2014-03620z_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl503620z'>ACS Electronic Supporting Info</A></P>
Choi, Sunghun,Kwon, Tae-woo,Coskun, Ali,Choi, Jang Wook American Association for the Advancement of Scienc 2017 Science Vol.357 No.6348
<P>Lithium-ion batteries with ever-increasing energy densities are needed for batteries for advanced devices and all-electric vehicles. Silicon has been highlighted as a promising anode material because of its superior specific capacity. During repeated charge-discharge cycles, silicon undergoes huge volume changes. This limits cycle life via particle pulverization and an unstable electrode-electrolyte interface, especially when the particle sizes are in the micrometer range. We show that the incorporation of 5 weight% polyrotaxane to conventional polyacrylic acid binder imparts extraordinary elasticity to the polymer network originating from the ring sliding motion of polyrotaxane. This binder combination keeps even pulverized silicon particles coalesced without disintegration, enabling stable cycle life for silicon microparticle anodes at commercial-level areal capacities.</P>
정성훈(Sunghun Jung),김용환(Yonghwan Kim),최혁재(Hyeokjae Choi),최대규(Daegyu Choi),이규송(Kyu-Song Lee) 한국전자파학회 2023 한국전자파학회논문지 Vol.34 No.5
본 논문에서는 광대역 전자전장비에서 소요되는 C∼K대역의 주파수 합성기를 설계 및 제작하였고, 측정결과를 소개하였다. 설계된 주파수 합성기는 mixer나 multiplier 없이 DDS(direct digital synthesis)를 구현하여 6 ㎓까지 신호를 생성하는 구조이며, 6 ㎓ 이상의 신호는 multiplier를 사용한 구조를 적용하였다. 또한, 불요신호, 고조파신호, 위상잡음 등의 신호품질 향상을 위해, 가변 샘플링 주파수 구조와 DDS부 회로를 설계하였다. 제작된 주파수 합성기는 multiplier의 사용 유무에 따라 신호품질 성능이 달라지며, C∼G대역은 출력신호세기 평탄도 ±1.7 ㏈, 불요신호 −55 ㏈c 이하, 위상잡음 −95 ㏈c/㎐(@1 ㎑) 이하의 특성을 가진다. Multiplier를 사용한 H∼K대역은 출력신호세기 평탄도 ±2.0 ㏈, 불요신호 −35 ㏈c 이하, 위상잡음 −80 ㏈c/㎐(@1 ㎑) 이하의 특성을 가진다. 본 논문의 결과를 통해 C∼K대역용 주파수 합성기를 소형화할 수 있었다. In this study, a C∼K band frequency synthesizer used in broadband electronic warfare equipment was designed, developed, and the measurement results were presented. The structure of the designed frequency synthesizer generates a signal up to 6 ㎓ using only direct digital synthesizer(DDS) without a mixer or multiplier. For signals above 6 ㎓ frequency, the structure uses a multiplier. In addition, a variable sampling frequency structure and a DDS circuit were designed to improve signal quality by reducing spurious signals, harmonic signals, and phase noise. The developed frequency synthesizer has different signal quality performance depending on the use of the multiplier, and the C∼G band has output power flatness ±1.7 ㏈, spurious signal less than −55 ㏈c, and phase noise less than −95 ㏈c/㎐ (@1 ㎑). The H∼K band using multiplier has characteristics of output power flatness ±2.0 ㏈, spurious signal less than −35 ㏈c, and phase noise less than −80 ㏈c/㎐ (@1 ㎑). The results of this study confirmed the miniaturization of the signal generation module in the C∼K band.
Geometric phase at a graphene edge: Scattering phase shift of Dirac fermions
Choi, Sang-Jun,Park, Sunghun,Sim, H.-S. American Physical Society 2014 Physical review. B, Condensed matter and materials Vol.89 No.15
We study the scattering phase shift of Dirac fermions at graphene edge. We find that when a plane wave of a Dirac fermion is reflected at an edge of graphene, its reflection phase is shifted by the geometric phase resulting from the change of the pseudospin of the Dirac fermion in the reflection. The geometric phase is the Pancharatnam-Berry phase that equals the half of the solid angle on Bloch sphere determined by the propagation direction of the incident wave and also by the orientation angle of the graphene edge. The geometric phase is finite at the zigzag edge in general, while it always vanishes at the armchair edge because of intervalley mixing. To demonstrate its physical effects, we first connect the geometric phase with the energy band structure of graphene nanoribbon with the zigzag edge. The magnitude of the band gap of the nanoribbon, that opens in the presence of the staggered sublattice potential induced by edge magnetization, is related to the geometric phase. Second, we numerically study the effect of the geometric phase on the Veselago lens formed in a graphene nanoribbon. The interference pattern of the lens is distinguished between armchair and zigzag nanoribbons, which is useful for detecting the geometric phase.