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345 results on '"Cho, Kang-Hee"'

3. Treating Interference as Noise is Optimal for Covert Communication over Interference Channels

Author

Cho, Kang-Hee and Lee, Si-Hyeon

Subjects
Computer Science - Information Theory
Abstract

We study the covert communication over K-user discrete memoryless interference channels (DM-ICs) with a warden. It is assumed that the warden's channel output distribution induced by K "off" input symbols, which are sent when no communication occurs, is not a convex combination of those induced by any other combination of input symbols (otherwise, the square-root law does not hold). We derive the exact covert capacity region and show that a simple point-to-point based scheme with treating interference as noise is optimal. In addition, we analyze the secret key length required for the reliable and covert communication with the desired rates, and present a channel condition where a secret key between each user pair is unnecessary. The results are extended to the Gaussian case and the case with multiple wardens., Comment: This paper was submitted to IEEE Transactions on Information Forensics and Security, and a shorter version of this paper was submitted to IEEE International Symposium on Information Theory (ISIT) 2020

Published
2020

7. Throughput Scaling of Covert Communication over Wireless Adhoc Networks

Author

Cho, Kang-Hee, Lee, Si-Hyeon, and Tan, Vincent Y. F.

Subjects
Computer Science - Information Theory
Abstract

We consider the problem of covert communication over wireless adhoc networks in which (roughly) $n$ legitimate nodes (LNs) and $n^{\kappa}$ for $0<\kappa<1$ non-communicating warden nodes (WNs) are randomly distributed in a square of unit area. Each legitimate source wants to communicate with its intended destination node while ensuring that every WN is unable to detect the presence of the communication. In this scenario, we study the throughput scaling law. Due the covert communication constraint, the transmit powers are necessarily limited. Under this condition, we introduce a preservation region around each WN. This region serves to prevent transmission from the LNs and to increase the transmit power of the LNs outside the preservation regions. For the achievability results, multi-hop (MH), hierarchical cooperation (HC), and hybrid HC-MH schemes are utilized with some appropriate modifications. In the proposed MH and hybrid schemes, because the preservation regions may impede communication along direct data paths, the data paths are suitably modified by taking a detour around each preservation region. To avoid the concentration of detours resulting extra relaying burdens, we distribute the detours evenly over a wide region. In the proposed HC scheme, we control the symbol power and the scheduling of distributed multiple-input multiple-output transmission. We also present matching upper bounds on the throughput scaling under the assumption that every active LN consumes the same average transmit power over the time period in which the WNs observe the channel outputs., Comment: The material in this paper will be presented in part at ISIT 2019 in Paris, France in July 2019

Published
2019

20. Iridium-Cooperated, Symmetry-Broken Manganese Oxide Nanocatalyst for Water Oxidation

Author

Park, Sunghak, Jang, Taehwan, Choi, Seungwoo, Lee, Yoon Ho, Cho, Kang Hee, Lee, Moo Young, Seo, Hongmin, Lim, Hyung Kyu, Kim, Yujeong, Ryu, Jinseok, Im, Sang Won, Kim, Min Gyu, Park, Ji-Sang, Kim, Miyoung, Jin, Kyoungsuk, Kim, Sun Hee, Park, Gyeong-Su, Kim, Hyungjun, and Nam, Ki Tae

Abstract

The water oxidation reaction, the most important reaction for hydrogen production and other sustainable chemistry, is efficiently catalyzed by the Mn4CaO5cluster in biological photosystem II. However, synthetic Mn-based heterogeneous electrocatalysts exhibit inferior catalytic activity at neutral pH under mild conditions. Symmetry-broken Mn atoms and their cooperative mechanism through efficient oxidative charge accumulation in biological clusters are important lessons but synthesis strategies for heterogeneous electrocatalysts have not been successfully developed. Here, we report a crystallographically distorted Mn-oxide nanocatalyst, in which Ir atoms break the space group symmetry from I41/amdto P1. Tetrahedral Mn(II) in spinel is partially replaced by Ir, surprisingly resulting in an unprecedented crystal structure. We analyzed the distorted crystal structure of manganese oxide using TEM and investigated how the charge accumulation of Mn atoms is facilitated by the presence of a small amount of Ir.

Published
2023
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25. High‐Throughput Pb Recycling for Perovskite Solar Cells Using Biomimetic Whitlockite.

Author

Hong, Jung Sug, Kim, Hee Jung, Sohn, Chang Hwun, Gong, Oh Yeong, Choi, Jin Hyuk, Cho, Kang Hee, Han, Gill Sang, Nam, Ki Tae, and Jung, Hyun Suk

Abstract

Pb contamination in aquatic environments causes severe pollution; therefore, harmless absorbents are required. In this study, we report a novel synthesis of whitlockite (WH, Ca18Mg2(HPO4)2(PO4)12), which is the second most abundant biomineral in human bone, and its application as a high‐performing Pb2+ absorbent. Hydroxyapatite (HAP) and WH are prepared via a simple precipitation method. The Pb2+ absorption performance and mechanism of the synthesized biominerals are investigated in aqueous solutions at neutral pH. The results demonstrate that WH exhibits an excellent Pb2+ absorption capacity of 2339 mg g−1, which is 1.68 times higher than the recorded value for HAP. Furthermore, the absorbed Pb2+ ions are recycled into high‐purity PbI2. This is employed as a precursor for the fabrication of perovskite solar cells (PSCs), resulting in a conversion efficiency of 19.00% comparable to that of commercial PbI2 powder (99.99% purity). Our approach provides an efficient way to remove Pb2+ ions from water and reuse them in the recycling of PSCs. [ABSTRACT FROM AUTHOR]

Published
2023
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31. Atomic Reconstruction and Oxygen Evolution Reaction of Mn3O4 Nanoparticles

Author

Yoon, Sangmoon, primary, Seo, Hongmin, additional, Jin, Kyoungsuk, additional, Kim, Hyoung Gyun, additional, Lee, Seung-Yong, additional, Jo, Janghyun, additional, Cho, Kang Hee, additional, Ryu, Jinseok, additional, Yoon, Aram, additional, Kim, Young-Woon, additional, Zuo, Jian-Min, additional, Kwon, Young-Kyun, additional, Nam, Ki Tae, additional, and Kim, Miyoung, additional

Published
2022
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35. Development and Evaluation of the Korean Version of Hospital-Based Transitional Rehabilitation Program Using Daily Living Home for Spinal Cord Injury

Author

Moon, Chang-Won, Jung, Il-Young, Kim, Ju Young, Jang, Ha Neul, and Cho, Kang Hee

Subjects
medicine.medical_specialty, Activities of daily living, Rehabilitation, business.industry, transitional care, medicine.medical_treatment, patient discharge, medicine.disease, Goal Attainment Scaling, rehabilitation, Quality of life, Physical therapy, medicine, Daily living, Medicine, Original Article, Transitional care, spinal cord injuries, business, activities of daily living, Spinal cord injury, Korean version
Abstract

Objective To develop and evaluate the Korean version of a hospital-based transitional rehabilitation program (TRP), using daily living home for spinal cord injury (SCI) patients.Methods In this study, we developed the Korean version of a hospital-based TRP through domestic and overseas surveys and focus group meetings. By applying this to chronic SCI patients, we observed the functional and quality of life (QOL) changes and evaluated the degree of achievement of the core goals set for each patient during hospital-based TRP.Results Hospital-based TRP, for 21.8±3.9 days on average, was applied to four chronic SCI patients (two patients with long-term hospital stays and two homebound disabled individuals) with an average injury period of 736.8±185.4 days. The Korean version of the Spinal Cord Independence Measure (49.3±6.9 vs. 62.5±6.0; p

Published
2021

37. Additional file 1 of Clinical evaluation of usefulness and effectiveness of sitting type continuous passive motion machines in patients with total knee arthroplasty: a study protocol for a single-blinded randomized controlled trial

Author

Lee, Byung Chan, Moon, Chang Won, Choi, Woo Sung, Kim, Young Mo, Joo, Yong Bum, Lee, Da Gyo, Lee, Sook Joung, Choi, Eun Seok, Ji, Jong Hun, Suh, Dong Whan, and Cho, Kang Hee

Subjects
Data_FILES
Abstract

Additional file 1.

Published
2022
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38. Additional file 2 of Clinical evaluation of usefulness and effectiveness of sitting type continuous passive motion machines in patients with total knee arthroplasty: a study protocol for a single-blinded randomized controlled trial

Author

Lee, Byung Chan, Moon, Chang Won, Choi, Woo Sung, Kim, Young Mo, Joo, Yong Bum, Lee, Da Gyo, Lee, Sook Joung, Choi, Eun Seok, Ji, Jong Hun, Suh, Dong Whan, and Cho, Kang Hee

Subjects
Data_FILES
Abstract

Additional file 2.

Published
2022
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39. The complete chloroplast genome of Korean cultivar ‘Harmony’ (Prunus salicina × Prunus armeniaca)

Author

Kim, Se Hee, Kwon, Jung-hyun, Cho, Kang Hee, Jun, Ji Hae, and Shin, Il Sheob

Abstract

Prunus Linnaeus 1753 species include many economically important fruit crops, of which plumcot is generated by inter-species crossing between Prunus salicina Lindley 1830 × Prunus armeniaca Linnaeus 1753. In this study, the complete chloroplast genome of Korean plumcot cultivar ‘Harmony’ was characterized through the de novo assembly of Nanopore and Illumina sequencing data. The chloroplast genome is a circular molecule of 157,916 bp length with 36.75% GC content and has a total of 113 genes including 79 protein-coding genes, 30 transfer RNA genes, and four ribosomal RNA genes. Phylogenetic analysis with protein-coding sequences of chloroplast genome revealed that ‘Harmony’ showed closer to P. salicina than P. armeniaca.

Published
2022
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