Search

Your search keyword '"Park, Cheol Min"' showing total 508 results
Start Over Author "Park, Cheol Min" Language english
508 results on '"Park, Cheol Min"'

33. Exploring the effects of two-segment loop tunnels on termite food transport efficiency: a simulation study.

Author

Lee, Sang-Hee and Park, Cheol-Min

Subjects
*TRAFFIC congestion, *FORAGING behavior, *TUNNELS, *TERMITES, *PROBABILITY theory
Abstract

This study explores the food transport efficiency (E) in a termite tunnel consisting of a main tunnel and a 2-segment loop tunnel through a model simulation. Simulated termites navigate between the main and loop tunnels through branching nodes (a , b , c , d) with associated probabilities (P 1, P 2, P 3, P 4). The loop tunnel locations (δ) are considered: near the nest (δ  = 1), at the center of the main tunnel (δ  = 2), and close to the food site (δ  = 3). The results reveal that for δ  = 1, paths such as a → d → b → c and c → d → b → a exhibited high E values. Conversely, for δ  = 2, P 3 and P 4 demonstrate elevated E values ranging from 0.4 to 0.6. For δ  = 3, paths like c → d or c → b display high E values, emphasizing the significance of in-loop separation tunnels (characterized by P 3 and P 4) in alleviating traffic congestion. Partial rank correlation validates that P 1 and P 2 minimally influence E , while P 3 and P 4 significantly negatively impact E , regardless of δ. However, for δ  = 2, the influence of P 3 and P 4 is notably reduced due to the positional symmetry of the loop tunnel. In the discussion, we address model limitations and propose strategies to overcome them. Additionally, we outline potential experimental validations to ensure a comprehensive understanding of the dynamics governing termite food transport within tunnels. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

43. Synthesis of 2‐Quinolones based on Visible Light‐Catalyzed Annulation of Diazo compounds.

Author

Bae, Jaehee, Chae, Jiyoung, and Park, Cheol‐Min

Subjects
ANNULATION, ACETAMIDE, CHARGE exchange, RADICALS (Chemistry), DIAZO compounds
Abstract

Herein, we report a photocatalytic method for the synthesis of 2‐quinolones under mild conditions by employing α‐diazo acetamide as substrates. The use of Eosin Y as a photocatalyst allows an economical and environmentally benign synthetic method. The process involves the generation of radicals from diazo compounds promoted by a visible‐light‐induced proton‐coupled electron transfer (PCET) mechanism. The method demonstrates a broad substrate scope to provide various aryl‐ and alkyl‐substituted 2‐quinolones. To support the proposed mechanism, a series of mechanistic experiments were conducted. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

44. Metallic cobalt/cobalt sulfide hetero-nanostructures embedded within N-doped graphitic carbon nanocages for the hydrogen evolution reaction.

Author

Mai, Hien Duy, Park, Poong Mo, Bae, Gi-Nam, Jeong, Sangmin, Seo, Beomwon, Cho, Minsong, Park, Sunyoung, Cuong, Nguyen Duc, Cuong, Tran Viet, Tran, Ngoc Minh, Park, Cheol-Min, and Jeon, Ki-Joon

Abstract

The development of low-cost, catalytically efficient, and durable earth-abundant electrocatalysts for replacing platinum-group-metal (PGM) materials has always been at the forefront of materials engineering for sustainable hydrogen generation. Metal–organic frameworks (MOFs), especially cobalt (Co)-based zeolitic imidazolate framework (ZIF-67) can be used as precursors or templates for preparing non-precious electrocatalysts. Herein, we successfully fabricated metallic cobalt/cobalt sulfide hetero-nanostructures embedded within N-doped graphitic carbon nanocages (Co/CoxSy@NC-750) by the one-step pyrolysis of ZIF-67 under H2 and S. Co/CoxSy@NC-750 exhibits a hollow configuration with a high degree of morphological uniformity. The pyrolysis temperature and resulting control of the composition played a crucial role in material engineering with application-oriented properties. Examination of the activity for the hydrogen evolution reaction (HER) in 0.5 M H2SO4 and 1.0 M KOH aqueous electrolytes demonstrated that Co/CoxSy@NC-750 exhibits substantially improved HER performance in both acidic (overpotential of 130 mV and Tafel slope of 82 mV dec−1) and basic (330 mV and 160 mV dec−1) media. The unique metallic cobalt core/cobalt sulfide shell is particularly beneficial for maintaining the electrochemical long-term durability (≥30 h and 40 h in acids and bases, respectively). This study provides guidance for achieving MOF-derived inorganic nanomaterials with the desired structural heterogeneity and compositional control for non-PGM electrochemical catalysis through fundamental quantification of the structural and catalytic parameters. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results