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Hwang, Sungho,Ko, Yeji,Park, Donguk,Yoon, Chungsik British Medical Association 2018 Journal of clinical pathology Vol.71 No.1
<P>Conclusions Airborne microbe concentrations in the LMR and LRR varied greatly depending on season, and these changes were affected by environmental factors.</P>
Radio Resource Allocation for Real-Time Traffic with Multi-Level Delay Constraint in OFDMA System
HWANG, Sungho,PARK, Jeongsik,CHO, Ho-Shin The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.5
<P>In this paper, an efficient radio resource allocation scheme for OFDMA systems is proposed, which follows two steps to take care of real-time traffic characterized with multi-level delay constraints. Urgent packets, those with imminent deadlines, are released first in step 1. After that the remaining channel resources are managed in such a way that overall throughput is maximized at Step 2. In this work, 2-dimensional diversity over multiple sub-bands and multiple users are jointly considered. The proposed scheme is compared with existing schemes designed for real-time traffic such as Exponential Scheduling (EXP) scheme, Modified Largest Weighted Delay First (M-LWDF) scheme, and Round robin scheme in terms of the packet discard probability and throughput. Numerical results show that the proposed scheme performs much better than the aforementioned ones in terms of the packet discard probability, while slightly better in terms of throughput.</P>
A Heuristic Method for Channel Allocation and Scheduling in an OFDMA System
Sungho Hwang,박준구,Youn Seon Jang,조호신 한국전자통신연구원 2008 ETRI Journal Vol.30 No.5
In this letter, a heuristic channel allocation and scheduling scheme is proposed. By comparing the size of the alternative-factor assessment, which is obtained by simple calculation, we can easily find the most appropriate channel for each user for overall throughput enhancement. Numerical results show that the downlink throughput of the proposed scheme is higher than that of proportional fairness and is almost the same as that of the maximum C/I scheme, while user fairness remains better than that of the maximum C/I scheme.
Hwang, Sungho,Roh, Jaehoon,Park, Wha Me Informa UK (TaylorFrancis) 2018 AEROSOL SCIENCE AND TECHNOLOGY Vol.52 No.4
<P>The purpose of this study was to compare the performance efficiency of melt-blown and currently used glass fiber filter media under the same environmental conditions. To evaluate filter efficiency, filter class was determined according to ISO and European standards (EN 1822-1:2009) using an automated filter tester (0.3m size), taking into account particle filtration, fractional efficiency for negative pressure devices, and consumption of electrical power. The average fractional efficiency, quality factor (QF), fractional efficiency by dust loading amount, pressure by dust loading amount, and QF by dust loading amount were higher in the case of melt-blown media than in the case of glass fiber filters. The fractional efficiency of hydrocharged melt-blown filters was higher than that of uncharged media. Based on performance efficiency, melt-blown filters are more effective high efficiency particulate air filters than glass fiber media.Copyright (c) 2018 American Association for Aerosol Research</P>
A Fast Converged Solution for Power Allocation of OFDMA System
Sungho Hwang,Ho-Shin Cho 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.2
In this paper, we propose a fast adaptive power allocation method for an orthogonal frequency division multiple access (OFDMA) system that employs an adaptive modulation and coding (AMC) scheme. The proposed scheme aims to reduce the calculation complexity of greedy adaptive power allocation (APA), which is known as the optimal algorithm for maximizing the utility argument of power. Unlike greedy APA, which starts power allocation from “0”, the proposed algorithm initially allocates a certain level of power determined by the water-filling scheme. We theoretically demonstrate that the proposed algorithm has almost the same capability of maximizing the utility argument as the greedy APA while reducing the number of operations by 2M, where M is the number of AMC levels.
A Fast Converged Solution for Power Allocation of OFDMA System
Hwang, Sungho,Cho, Ho-Shin The Korean Institute of Electrical Engineers 2014 Journal of Electrical Engineering & Technology Vol.9 No.2
In this paper, we propose a fast adaptive power allocation method for an orthogonal frequency division multiple access (OFDMA) system that employs an adaptive modulation and coding (AMC) scheme. The proposed scheme aims to reduce the calculation complexity of greedy adaptive power allocation (APA), which is known as the optimal algorithm for maximizing the utility argument of power. Unlike greedy APA, which starts power allocation from "0", the proposed algorithm initially allocates a certain level of power determined by the water-filling scheme. We theoretically demonstrate that the proposed algorithm has almost the same capability of maximizing the utility argument as the greedy APA while reducing the number of operations by 2M, where M is the number of AMC levels.
A Throughput Enhancement under a Strict Fairness Constraint in OFDMA System
HWANG, Sungho,PARK, Soonchul,CHO, Ho-Shin The Institute of Electronics, Information and Comm 2011 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.eb94 No.1
<P>In this paper, we mathematically derive a matrix-form solution named resource allocation matrix (RAM) for sub-band allocation in an orthogonal frequency division multiple access (OFDMA) system. The proposed scheme is designed to enhance throughput under a strict user fairness condition such that every user has an equal number of sub-bands per frame. The RAM designates the most preferable sub-band for every user. The proposed scheme is evaluated in terms of throughput and user fairness by comparison with the proportional fairness (PF) scheme and greedy scheme. Numerical results show that the proposed scheme has overwhelming superiority to other schemes in terms of fairness and tight competitive in terms of throughput.</P>