• Korean Journal of Environmental Biology
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• v.38 no.1
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• pp.114-126
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• 2020

Bloom-forming toxic cyanobacteria Microcystis spp. are common in the summer season in temperate freshwater ecosystems. Often, it leads to the degradation of water quality and affects the quality of drinking water. In a previous study, NQ (naphthoquinone) compounds were shown to be effective, selective, and ecologically safe algicides for Microcystis spp. blooms. To analyze the superiority of developed NQ derivatives, we conducted a microcosm experiment using clay, which is frequently used in South Korea. Similar to previous studies, the NQ 40 and NQ 2-0 compounds showed high algicidal activities of 99.9% and 99.6%, respectively, on Microcystis spp. at low concentrations (≥1 μM) and enhanced phytoplankton species diversity. However, when treated with clay, a temporary algicidal effect was seen at the beginning of the experiment that gradually increased at the end. In addition, treatment with the NQ compounds did not affect either the abiotic or biological factors, and similar trends were observed with the control. These results showed that the NQ 2-0 compound was more effective, with no ecosystem disturbance, and more economical than the currently used clay. These results suggest that NQ 2-0 compound could be a selective, economically and ecologically safe algicide to mitigate harmful cyanobacterial blooms in the field.

• Korean Journal of Microbiology
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• v.52 no.3
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• pp.269-277
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• 2016

Erm proteins methylate the specific adenine residue ($A_{2058}$, E. coli numbering) on 23S rRNA to confer the $MLS_B$ (macrolidelincosamide-streptogramin B) antibiotic resistance on a variety of microorganisms ranging from antibiotic producers to pathogens. When phylogenetic tree is constructed, two main clusters come out forming each cluster of Actinobacteria and Firmicutes. Two representative Erm proteins from each cluster were selected and their in vitro methylation activities were compared. ErmS and ErmE from Actinobacteria cluster exhibited much higher activities than ErmB and ErmC' from Firmicutes: 9 fold difference when ErmC' and ErmE were compared and 13 fold between ErmS and ErmB. Most of the difference was observed and presumed to be caused by N-terminal and C-terminal extra region from ErmS and ErmE, respectively because NT59TE in which N-terminal end 59 amino acids was truncated from wild type ErmS exhibited only 22.5% of wild type ErmS activity. Meanwhile, even NT59TE showed three and 2.2 times more activity when it was compared to ErmB and C, respectively, suggesting core region from antibiotic producers contains extra structure enabling higher activity. This is suggested to be possible through the extra region of 197RWS199 (from both ErmS and ErmE), 261GVGGSLY267 (from ErmS), and 261GVGGNIQ267 (from ErmE) and 291SVV293 (from ErmS) and 291GAV293 (from ErmE) by multiple sequence alignment.

• Korean Journal of Veterinary Research
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• v.44 no.3
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• pp.433-439
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• 2004

This study was carried out to investigate the efficacy of rifampin with or without streptomycin in male Sprague-Dawley (SD) rats experimentally inoculated with Brucella abortus. Thirty rats were intraperitoneally inoculated with $1.0{\times}10^9$colony-forming units of B. abortus. They were divided into 3 groups by treatment with antibiotic. 10 rats in Group A were orally administrated with rifampin, 10 rats in Group B with rifampin orally and with streptomycin intramuscularly over 12 weeks starting at 1 week post infection (PI). A placebo recipient in Group C was inoculated with sterile saline without antibiotics. All animals were monitored by tube agglutination test (TAT) and AMOS-PCR to evaluate the efficiency of the antibiotics to B. abortus infection. The antibody titers in Groups A, B and C were 1:400, 1:400 and 1:800 as measured by TAT at the first week PI, respectively. The antibody titer in Group A decreased to 1:100 by the 13th week PI. That in the control group was observed as high antibody titer until 13th weeks PI, but the antibody response in Group B was low(1:50) from the 5th week to the 13th week PI. AMOS-PCR there was evidence of relapse of B. abortus in group A in liver and spleen specimens at the 13th week PI. B. abortus DNA was detected in Group C in liver and spleen specimens from the 1st week to 13th week PI by AMOS-PCR. However AMOS-PCR could not detect any organism in Group B from the 3rd week PI until the end of the study. This study demonstrated that administration of a combination of rifampin and streptomycin was more efficacious than administration of rifampin alone. A significant reduction in antibody titer was observed when a combination of 15 mg/kg/day of rifampin per os and 15 mg/kg/day streptomycin intramuscularly was used in comparison with the antibody of control group.

• Journal of Korea Game Society
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• v.9 no.3
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• pp.23-33
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• 2009

This study aims to uncover the gamers' cognitive process during the gameplay and explore the differences between groups in the gamers' playing behavior according to their expertise: experts, intermediate players, and novices. To this end, the empirical experiment was conducted in 'World of Warcraft' game which is a good representative of MMO(Massively Multi-player Online) game currently. Verbal protocol and action protocol collected from the empirical experiment were analyzed according to the gamers' expertise. As a result of this study, we found that the different behavior patterns result from standardizing pattern of their actions for experts and forming the learning curves and the specific patterns of action for intermediate game players and novices. While three functional-actions as a collection action concentrates on the early stage of the game for experts, the novices' behavior pattern dispersedly appeared in all seven functional-action, such as search, combat, three type collections, avoid, and communication in the whole gameplay. This study represents the consistency and the difference derived from the comparison analysis between groups according to the expertise. This study is concluded with key implications to support game design guidelines according to experts, intermediate players, and novices. Consequently, the result of this study provides the basic to the development of MMO content for game novices.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.78-84
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• 2016

In this work, finite element investigations were carried out to optimize reverse drawing process design for manufacture of high-capacity aluminum liner used in fuel cell vehicle. The tensile tests with aluminum alloy Al6061 annealed at $350^{\circ}C$ were carried out to obtain the flow stresses. In order to estimate more accurate flow stresses after necking, the flow stresses were estimated from the comparison of load vs. displacement curves which were obtained from experimental and simulation results of tensile tests. In case of finite element analyses of reverse drawing processes, it was focused on the effects of process designs such as punch and die designs, blank holding force, drawing ratio and the clearance between the punch and blank holder on the generation of wrinkle and fracture of the blank and partially heated punch. However, it was revealed that experimental results still show the fracture at the end of 2nd drawn cup, although partially heated punch is used. Nevertheless, the drawn cup can be used because the sufficient length of the drawn cup for the next flow forming process and spinning process was obtained.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.198-201
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• 2015

The prompt and accurate location determination of the nodes of the wireless indoor shipboard networks is crucial to forming the stable wireless shipboard sensor networks. To this end in this paper it can be achieved through the measurement of the bi-directional channel qualities among the nodes after the locations of the sensor nodes temporarily placed. For the 1st stage the piconet-type sensor networks are considered to measure the channel qualities between a specific node and the cluster node which is the master node. After finishing the 1st stage measurement the nodes needing the relay nodes are selected and the measurement action goes into the 2nd stage. In the 2nd stage the measurement between a candidate relay node and the node needing a relay node starts to begin. After the 2nd stage the relay nodes to connect to the cluster node are fixed and the information delivery paths between a node and the cluster head are established. In this paper the measurement results in the realistic environment are gathered and analysed to show that the measurement procedure can be applied in the wireless indoor shipboard networks.

• Journal of the Society of Disaster Information
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• v.8 no.2
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• pp.158-170
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• 2012

Citizens'income has been increased along with the trend of rapid changes in society, and the quality of their lives has been improved as well. As much as the degree of increase of quality of life, the number of spectators for performing art events, etc. who desire to fulfill their needs for enjoyment of varied cultural performances have been increasing, and also a large number of spectators enjoys a variety of festivals being held in each provincial area as well as international events: we still remember such frantic rooting shown by citizens during 2002 World Cup drawing attention and interest of entire nation. There are always risks of loss of human lives if accidents occur as there sult of close-packed crowd gathered at the same time. Therefore, it is required to prepare adequate security measures in order to prevent various accidents before hand. It is hoped that this research work would be of help for further efficient and systematic security management for the performing arts centers or public theaters encouraging the event organizer and the private security firm and the Korea Private Security Association to exert great effort and investments in further projects for development of security technology. Also, it is required to build a performance culture to consider audience's safety first from the beginning to the end of the event on the basis of efficient security management. Furthermore, spect at or sare required to recognize the fact that safety in the site for performing arts should be guaranteed for everyone's sake, and, to achieve this, they are obliged to be more cooperative with the event organizer and the private security firm, forming a trinity all together, in order not to have safety threatening situations in the site of performing arts events.

• Korean Journal of Plant Tissue Culture
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• v.27 no.3
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• pp.185-189
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• 2000

For the micropropagation, node explants of cassava were cultured in liquid MS medium with various concentrations of cytokinins on a rotary shaker (100 rpm) for 2 weeks. The adventitious roots and shoots from the explants were differentiated more efficiently in liquid medium than in solid. But root formation was not inhibited in medium with BAP and kinetin at low concentration (＞0.05 mg 1/sup -1/), while in medium added with BAP and zeatin at high level (＜0.25 mg 1/sup -1/), it was inhibited by callus forming on cut end of the cuttings. However, all of plantlets grown in liquid medium for more than 2 weeks showed symptoms of hyperhydricity. The plantlets grown in liquid medium were transferred into culture bottles filled with fine sand or artificial soil (pitmoss：perlite：vermiculite, 1：1：1 v/v) wetted with half strength of Knop's solution. After transplanted to culture bottles, some of vitriscent leaves were defoliated and new leaves were normally formed from shoot apex. Most of plantlets (＞95%) were hardened-off successfully only in culture bottles with fine sand, and grew into 3-5 cm seedlings possessing 4-6 nodes after 4 weeks. Thus, the mass propagation of cassava on medium containing cytokinin could be established based on the suspension culture using node explants.

• Korean Journal of Social Welfare Studies
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• v.48 no.3
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• pp.57-81
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• 2017

As of the end of the year 2016, the foreigners staying in Korea have surpassed 2 million people for the very first time ever since the statistical writings began. Because the inflow of the foreigners has been greatly increased within a short time period, the Korean society has been rapidly changing into a multi-racial and multi-ethnic society, and the children of the multicultural families, too, have been increasing gradually. Because of the social prejudices, discriminations, negative recognitions, etc., the children of the multicultural families get exposed to the diverse problems. It can be considered that such social prejudices and negative recognitions comprise the discourses that are possessed by the constituent members of the society regarding a certain subject or phenomenon. By analyzing the special characteristics and discourses of the reports on the multicultural children and youths by the Korean press through newspaper articles, this research confirmed what influences the media have in the process of forming the recognitions regarding the multicultural children and youths at present. As a result of the research, the discourses appearing in the newspapers could be typed into the support emphasizing frame of the Korean society, the adaptation emphasizing frame of the Korean society, the global people of talent frame, the change emphasizing frame of the Korean society, and the social problem emphasizing frame. Based on such research results, I made a proposal regarding the direction for the desirable reports by the media.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.345-349
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• 2019

In Korea, the mountainous area occupies more than 70% of the whole country, cutting of earth slope that cuts a part of the ground surface is widely used when building infrastructures such as road, railroad, and industrial complex construction. In recent years, regulations on environmental damage have become more strict, and various methods have been developed and applied. Among them, Concrete-Panel Retaining Wall technique is actively applied. Concrete-Panel Retaining Wall is a method to resist horizontal earth pressure by forming a wall by attaching a precast retaining wall to the front of the support material and increasing the shear strength of the disk through reinforcement of the support material. Soil nailing, earth bolt, and ground anchor are used as support material. Among them, ground anchor is a more aggressive reinforcement type that introduces tensile load in advance to the steel wire, and a large concentrated load acts on the front panel. This concentrated load is a factor that creates cracks in the concrete panel and reduces the durability of the retaining wall itself. In this study, steel pipe sleeves and reinforcements were purchased at the anchorage of the panel to prevent cracks, and by applying bumpy shear keys to the end of the panel, the weakness of the individual behavior of the existing grout anchors was improved. The problem of degraded landscape by exposure to front concrete of retaining wall and protrusion of anchorage was solved by the production of natural stone patterns and the construction of sections that do not protrude the anchorage. In order to verify the effectiveness of anti-crack sleeves and reinforcements used in the null, indoor testing and three-dimensional numerical analysis have been performed, and the use of steel pipe sleeves and reinforcements has demonstrated the overall strength increase and crack suppression effect of panels.