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123 results on '"Byun, Woo Jin"'

2. Performance Analysis of Satellite Communication System Under the Shadowed-Rician Fading: A Stochastic Geometry Approach

Author

Jung, Dong-Hyun, Ryu, Joon-Gyu, Byun, Woo-Jin, and Choi, Junil

Subjects
Computer Science - Information Theory, Electrical Engineering and Systems Science - Signal Processing
Abstract

In this paper, we consider downlink low Earth orbit (LEO) satellite communication systems where multiple LEO satellites are uniformly distributed over a sphere at a certain altitude according to a homogeneous binomial point process (BPP). Based on the characteristics of the BPP, we analyze the distance distributions and the distribution cases for the serving satellite. We analytically derive the exact outage probability, and its approximated expression is obtained using the Poisson limit theorem. With these derived expressions, the system throughput maximization problem is formulated under the satellite-visibility and outage constraints. To solve this problem, we reformulate it with bounded feasible sets and propose an iterative algorithm to obtain near-optimal solutions. Simulation results perfectly match the derived exact expressions for the outage probability and system throughput. The analytical results of the approximated expressions are fairly close to those of the exact ones. It is also shown that the proposed algorithm for the throughput maximization is very close to the optimal performance obtained by a two-dimensional exhaustive search., Comment: 15 pages, 14 figures, 1 table, accepted by IEEE Transactions on Communications

Published
2021
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5. CO2 Enrichment Boosts Highly Selective Infrared‐Light‐Driven CO2 Conversion to CH4 by UiO‐66/Co9S8 Photocatalyst

Author

Yang, Siheng, primary, Byun, Woo Jin, additional, Zhao, Fangming, additional, Chen, Dingwen, additional, Mao, Jiawei, additional, Zhang, Wei, additional, Peng, Jing, additional, Liu, Chengyuan, additional, Pan, Yang, additional, Hu, Jun, additional, Zhu, Junfa, additional, Zheng, Xueli, additional, Fu, Haiyan, additional, Yuan, Maolin, additional, Chen, Hua, additional, Li, Ruixiang, additional, Zhou, Meng, additional, Che, Wei, additional, Baek, Jong‐Beom, additional, Lee, Jae Sung, additional, and Xu, Jiaqi, additional

Published
2024
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6. Phosphorus-Modified Palladium and Tungsten Carbide/Mesoporous Carbon Composite for Hydrogen Oxidation Reaction of Proton Exchange Membrane Fuel Cells.

Author

Bae, Ganghong, Byun, Woo Jin, Lee, Jin Ho, Lee, Min Hee, Choi, Yeji, Kim, Jae Young, and Youn, Duck Hyun

Subjects
*PROTON exchange membrane fuel cells, *TUNGSTEN carbide, *HYDROGEN oxidation, *CARBON composites, *OXIDATION of methanol, *EXCHANGE reactions
Abstract

A composite material of tungsten carbide and mesoporous carbon was synthesized by the sol-gel polycondensation of resorcinol and formaldehyde, using cetyltrimethylammonium bromide as a surfactant and Ludox HS-40 as a porogen, and served as a support for Pd-based electrodes. Phosphorus-modified Pd particles were deposited onto the support using an NH3-mediated polyol reduction method facilitated by sodium hypophosphite. Remarkably small Pd nanoparticles with a diameter of ca. 4 nm were formed by the phosphorus modification. Owing to the high dispersion of Pd and its strong interaction with tungsten carbide, the Pd nanoparticles embedded in the tungsten carbide/mesoporous carbon composite exhibited a hydrogen oxidation activity approximately twice as high as that of the commercial Pt/C catalyst under the anode reaction conditions of proton exchange membrane fuel cells. [ABSTRACT FROM AUTHOR]

Published
2024
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10. High-Performance Electrochemical and Photoelectrochemical Water Splitting at Neutral pH by Ir Nanocluster-Anchored CoFe-Layered Double Hydroxide Nanosheets

Author

Yu, Je Min, primary, Song, Jaejung, additional, Kim, Young Kyeong, additional, Oh, Jiyeon, additional, Kim, Kwang Young, additional, Noh, Woo Yeong, additional, Byun, Woo Jin, additional, Lee, Jin Uk, additional, Yang, Changduk, additional, Jang, Ji-Wook, additional, Lee, Jae Sung, additional, and Cho, Seungho, additional

Published
2023
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17. Activating the surface and bulk of hematite photoanodes to improve solar water splitting† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c9sc04110a

Author

Zhang, Hemin, Park, Jong Hyun, Byun, Woo Jin, Song, Myoung Hoon, and Lee, Jae Sung

Subjects
Chemistry
Abstract

Waking up the hematite lion: a simple electrochemical activation treatment leads to surface passivation outside and generation of oxygen vacancies inside, which greatly enhances photoelectrochemical water splitting., A simple electrochemical activation treatment is proposed to improve effectively the photoelectrochemical performance of Nb,Sn co-doped hematite nanorods. The activation process involves an initial thrice cathodic scanning (reduction) and a subsequent thrice anodic scanning (oxidation), which modifies both the surface and bulk properties of the Nb,Sn:Fe2O3 photoanode. First, it selectively removes the surface components to different extents endowing the hematite surface with fewer defects and richer Nb–O and Sn–O bonds and thus passivates the surface trap states. The surface passivation effect also enhances the photoelectrochemical stability of the photoanode. Finally, more Fe2+ ions or oxygen vacancies are generated in the bulk of hematite to enhance its conductivity. As a result, the photocurrent density is increased by 62.3% from 1.88 to 3.05 mA cm–2 at 1.23 VRHE, the photocurrent onset potential shifts cathodically by ∼70 mV, and photoelectrochemical stability improves remarkably relative to the pristine photoanode under simulated sunlight (100 mW cm–2).

Published
2019

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