• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.4A
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• pp.332-340
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• 2010

In this paper, we deal with multi-user diversity scheduling methods that transmit simultaneously signals from multiple users using superposition coding multiplexing. These methods can make various scheduling methods be obtained, according to strategies for user selection priority from the first user to the first-following users, strategies for per-user power allocation, and resulting combining strategies. For the first user selection, we consider three strategies such as 1) higher priority for a user with a better channel state, 2) following the proportional fair scheduling (PFS) priority, 3) higher priority for a user with a lower average serving rate. For selection of the first-following users, we consider the identical strategies for the first user selection. However, in the second strategy, we can decide user priorities according to the original PFS ordering, or only once an additional user for power allocation according to the PFS criterion by considering a residual power and inter-user interference. In the strategies for power allocation, we consider two strategies as follows. In the first strategy, it allocates a power to provide a permissible per-user maximum rate. In the second strategy, it allocates a power to provide a required per-user minimum rate, and then it reallocates the residual power to respective users with a rate greater than the required minimum and less than the permissible maximum. We consider three directions for scheduling such as maximizing the sum rate, maximizing the fairness, and maximizing the sum rate while maintaining the PFS fairness. We select the max CIR, max-min fair, and PF scheduling methods as their corresponding reference methods [1 and references therein], and then we choose candidate scheduling methods which performances are similar to or better than those of the corresponding reference methods in terms of the sum rate or the fairness while being better than their corresponding performances in terms of the alternative metric (fairness or sum rate). Through computer simulations, we evaluate the sum rate and Jain’s fairness index (JFI) performances of various scheduling methods according to the number of users.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.2B
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• pp.97-109
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• 2012

In this paper, we propose a modulation scheme for a network-coded bi-directional relaying (NBR) system over an asymmetric channel, which means that the qualities of the relay channel (the link between the BS and RS) and access channel (the link between the RS and MS) are not identical. The proposed scheme employs a dual constellation in such a way that the RS broadcasts the network-coded symbols modulated by two different constellations to the MS and BS over two consecutive transmission intervals. We derive an upper bound on the average bit error rate (BER) of the proposed scheme, and compare it with the hybrid constellation-based modulation scheme proposed for the asymmetric bi-directional link. Furthermore, we investigate the channel utilization of the existing bi-directional relaying schemes as well as the NBR system with the proposed dual constellation diversity-based modulation (DCD). From our simulation results, we show that the DCD gives better average BER performance about 3.5~4dB when $E_b/N_0$ is equal to $10^{-2}$, while maintaining the same spectral efficiency as the existing NBR schemes over the asymmetric bi-directional relaying channel.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.3 no.4
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• pp.795-804
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• 1999

The increasing number of users of mobile communication systems and the corresponding need for increased system capacity require the use of a modulation scheme which is both power and spectrally efficient. In this paper, we numerically calculate the BER performance of DS/CDMA-BPSK system in different fading channel (Rayleigh, Rician, Shadow Rician). Also, we calculate BER performance and the channel capacity of DS/CDMA-BPSK system which is constant or nearly constant envelopes in 3-state fading channel model. The Shadow Rician fading model described in this paper apply the parameters of the Canadian Mobile Satellite (MSAT). And we assume that the 3-state fading channel model is consist of Rayleigh fading state, Rician fading state, and shadow Rician fading state. This model can be used as a basis for the simulation of the land mobile satellite channel. The dynamic 3-state fading channel model is considered corresponding to different environments and the transitions between these environments. From the numerically calculate results, the DS/CDMA-BPSK system with MUI-20, PG-511 can not achieve the BER performance ($P_b\leq10^{-5}$). And the channel capacity did not meet the system requirement. Also, we know that the BER performance is depend m the occupancy probability of radio channel and the degree of shadow. From the results, we how that during shadowed time intervals it is necessary to use some form of error control coding and receiver diversity in order to support reliable data communication.

• Korean Journal of Microbiology
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• v.55 no.1
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• pp.74-76
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• 2019

Gram-positive anaerobic bacilli Actinomyces spp. commonly reside on mucosal surfaces of the oropharynx, gastrointestinal tract, and urogenital tract. Here, we first report the draft genome sequence of Actinomyces georgiae KHUD_A1, isolated from dental plaque of a Korean elderly woman. The genome is 2,652,059 bp in length and has a GC content of 68.06%. The genome includes 2,242 protein-coding genes, 9 rRNAs, and 64 tRNA. We identified 157 KHUD_A1 strain-specific genes, including genes encoding CPBP family intramembrane metalloprotease, bile acid: sodium symporter family protein, Txe/YoeB family addiction module toxin and Phd/YefM family antitoxin. The sequence information of A. georgiae KHUD_A1 will help understand the general characteristics of the bacterial species and the genome diversity of the genus Actinomyces.

• Journal of Korean Home Economics Education Association
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• v.32 no.2
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• pp.159-178
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• 2020

This study aimed at exploring male home economics(HE) teachers' identities through narrative inquiry. Considering experiences of HE teachers and diversity in regions, twelve male teachers were chosen, and in-depth interviews were conducted between June 1st and July 31st, 2019. The transcription of the data was transferred to the Hancom Office Hangeul 2010 while the researcher listened to the recordings of the interviews. The total amount of transcription data was 174 pages, and the data were analyzed through open coding, categorization, and category verification. The themes identified as results of this study were as follows: First, 'Coincidence: Breaking the Wall of Prejudice' is related to the experiences that have a great influence on the formation of identity as a male HE teacher: motivation to enter the HE department, educational practice, etc. Through this, the experience of becoming a male HE teacher was recorded. Second, 'Facing: Surviving as a male HE Teacher' captures the current story of male HE teachers and the perspectives of their fellow teachers, family, and friends about male HE teachers. In this section, male HE teachers showed how HE classes and assessments, and their experiences in their lives, influenced their identities. Third, 'Expectations: Growing as a HE teacher' is a story about the future of male HE teachers. The ideal teacher image pursued by male HE teachers was a practical teacher. They hoped that in 10 or 20 years, they would have smooth and professional relationship with students. They advise prospective male HE teachers to become a competent HE teacher regard less of their gender. The significance of this study is that it broke the stereotype of 'HE teachers should be female' and expanded the horizon of HE education by exploring the identities of male HE teachers.

• Restorative Dentistry and Endodontics
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• v.30 no.5
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• pp.409-422
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• 2005

The aim of this study was to identify the bacteria isolated from acute endodontic lesions by cell culture and 16S rDNA sequencing. The necrotic pulpal tissue was collected from 17 infected root canals, which were diagnosed as being either an acute pulpitis or acute periapical abscess. Samples were collected aseptically from the infected pulpal tissue of the infected root canals using a barbed broach and a paper point. The cut barbed broaches and paper points were transferred to an eppendorf tube containing 500 ul of 1 XPBS. The sample solution was briefly mixed and plated onto a BHI-agar plate containing $5\%$ sheep blood. The agar plates were incubated in a $37^{\circ}C$ anaerobic chamber for 7 days. The bacteria growing on the agar plate were identified by 16S rRNA coding gene (rDNA) cloning and sequencing at the species level. Among the 71 colonies grown on the agar plates, 56 strains survived and were identified. In dental caries involving the root canals, Streptococcus spp. were mainly isolated. Actinomyces, Clostridia, Bacteroides and Fusobacteria were isolated in the periapical lesion without dental caries. Interestingly, two new Actinomyces spp. (ChDC B639 and ChDC B631) were isolated in this study. These results showed that there was diversity among the species in endodontic lesions, This suggests that an endodontic infection is a mixed infection with a polymicrobial etiology. These results may offer the bacterial strains for pathogenesis studies related to an endodontic infection.