• Annals of Laboratory Medicine
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• v.38 no.6
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• pp.555-562
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• 2018

Background: The emerging mobile colistin resistance gene, mcr-1, is an ongoing worldwide concern and an evaluation of clinical isolates harboring this gene is required in Korea. We investigated mcr-1-possessing Enterobacteriaceae among Enterobacteriaceae strains isolated in Korea, and compared the genetic details of the plasmids with those in Escherichia coli isolates from livestock. Methods: Among 9,396 Enterobacteriaceae clinical isolates collected between 2010 and 2015, 1,347 (14.3%) strains were resistant to colistin and those were screened for mcr-1 by PCR. Colistin minimum inhibitory concentrations (MICs) were determined by microdilution, and conjugal transfer of the mcr-1-harboring plasmids was assessed by direct mating. Whole genomes of three mcr-1-positive Enterobacteriaceae clinical isolates and 11 livestock-origin mcr-1-positive E. coli isolates were sequenced. Results: Two E. coli and one Enterobacter aerogenes clinical isolates carried carried IncI2 plasmids harboring mcr-1, which conferred colistin resistance (E. coli MIC, 4 mg/L; E. aerogenes MIC, 32 mg/L). The strains possessed the complete conjugal machinery except for E. aerogenes harboring a truncated prepilin peptidase. The E. coli plasmid transferred more efficiently to E. coli than to Klebsiella pneumoniae or Enterobacter cloacae recipients. Among the three bacterial hosts, the colistin MIC was the highest for E. coli owing to the higher mcr-1-plasmid copy number and mcr-1 expression levels. Ten mcr-1-positive chicken-origin E. coli strains also possessed mcr-1-harboring IncI2 plasmids closely related to that in the clinical E. aerogenes isolate, and the remaining one porcine-origin E. coli possessed an mcr-1-harboring IncX4 plasmid. Conclusions: mcr-1-harboring IncI2 plasmids were identified in clinical Enterobacteriaceae isolates. These plasmids were closely associated with those in chicken-origin E. coli strains in Korea, supporting the concept of mcr-1 dissemination between humans and livestock.

• Journal of Veterinary Science
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• v.22 no.5
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• pp.68.1-68.15
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• 2021

Background: Colistin and carbapenem-resistant bacteria have emerged and become a serious public health concern, but their epidemiological data is still limited. Objectives: This study examined colistin and carbapenem resistance in Escherichia coli and Salmonella from pigs, pig carcasses, and pork in Thailand, Lao PDR, and Cambodia border provinces. Methods: The phenotypic and genotypic resistance to colistin and meropenem was determined in E. coli and Salmonella obtained from pigs, pig carcasses, and pork (n = 1,619). A conjugative experiment was performed in all isolates carrying the mcr gene (s) (n = 68). The plasmid replicon type was determined in the isolates carrying a conjugative plasmid with mcr by PCR-based replicon typing (n = 7). The genetic relatedness of mcr-positive Salmonella (n = 11) was investigated by multi-locus sequence typing. Results: Colistin resistance was more common in E. coli (8%) than Salmonella (1%). The highest resistance rate was found in E. coli (17.8%) and Salmonella (1.7%) from Cambodia. Colistin-resistance genes, mcr-1, mcr-3, and mcr-5, were identified, of which mcr-1 and mcr-3 were predominant in E. coli (5.8%) and Salmonella (1.7%), respectively. The mcr-5 gene was observed in E. coli from pork in Cambodia. Two colistin-susceptible pig isolates from Thailand carried both mcr-1 and mcr-3. Seven E. coli and Salmonella isolates contained mcr-1 or mcr-3 associated with the IncF and IncI plasmids. The mcr-positive Salmonella from Thailand and Cambodia were categorized into two clusters with 94%-97% similarity. None of these clusters was meropenem resistant. Conclusions: Colistin-resistant E. coli and Salmonella were distributed in pigs, pig carcasses, and pork in the border areas. Undivided-One Health collaboration is needed to address the issue.

• Journal of Microbiology and Biotechnology
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• v.30 no.12
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• pp.1862-1869
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• 2020

The spread of plasmid-mediated colistin resistance has posed a serious threat to public health owing to its effects on the emergence of pandrug-resistant bacteria. In this study, we investigated the prevalence and characteristics of mcr-1-positive Escherichia coli isolated from retail meat samples in Korea. In total, 1,205 E. coli strains were isolated from 3,234 retail meat samples in Korea. All E. coli strains were subjected to antimicrobial susceptibility testing and were examined for the presence of mcr-1 gene. All mcr-1-positive E. coli (n = 10, 0.8%) from retail meat were subjected to pulse-field gel electrophoresis (PFGE) and whole-genome sequencing (WGS). The transferability of mcr-1 gene was determined by conjugation assays. The mcr-1-positive strains exhibited diverse clonal types. Our mcr-1 genes were located in plasmids belonged to the IncI2 (n = 1) and IncX4 (n = 8) types, which were reported to be prevalent in Asia and worldwide, respectively. Most mcr-1 genes from mcr-1-positive strains (9/10) were transferable to the recipient strain and the transfer frequencies ranged from 2.4 × 10-3 to 9.8 × 10-6. Our data suggest that the specific types of plasmid may play an important role in spreading plasmid-mediated colistin resistance in Korea. Furthermore, our findings suggest that the retail meat may be an important tool for disseminating plasmid-mediated colistin resistance.

• Journal of the Korean Society of Systems Engineering
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• v.6 no.1
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• pp.47-52
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• 2010

Human Factors Engineering (HFE) for Main Control Room (MCR) of Nuclear Power Plant (NPP) has been applied to optimize the design and operation of Man-Machine Interface (MMI) between operators and their equipment in consideration of physical, psychological and cognitive aspects. However, it has been observed that operators complain about environmental discomfort in the MCR since the operators in the MCR experience excessive stress due to the environmental factors such as inappropriate interior and lighting system. Since the HFE is an essential factor for the high fidelity performance of operators in the MCR, the adequate MCR environment design with HFE rules and guidelines is as much important to enhance the operability and reliability of the MCRs. Therefore, there has been a strong need to design a pleasant environment for the MCR to improve human performance of the operators.

• The Journal of the Korean life insurance medical association
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• v.27 no.1
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• pp.33-36
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• 2008

BACKGROUND : The medical claims review(MCR) is unique methodology of medical consultation in terms of insurance claim administration in Korean insurance market. The most important practical matter in the MCR is formatted question. In Korea, medical specialty is composed of 26 legally defined hospital departments. It is worth of studying to investigate type of MCR by hospital departments. METHODS : Fifty Cases of the MCR were selected randomly by statistical program SPSS among 1,032 cases which were performed between April 1, 2006 and March 31 2007. All of selected cases were evaluated one insurance doctor and made a score points from 0 to 10 in terms of hospital department. RESULTS : Multidimensional scaling was performed. The MCR types - diagnosis, malignancy and cause of death are located in the same 2-dimensional configuration area. It can be called as verification of benefit. Others are advice. - such as causality, interpretation, translation, independent medical examination, and so on. DISCUSSION : We can conclude the classification of MCR typology are two main subjects, verification and advice. Theses results are same as previous article which was based on experience.

• IE interfaces
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• v.17 no.spc
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• pp.37-45
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• 2004

Human factors engineering design guidelines for main control rooms(MCR) in nuclear power plants(NPP) have been applied to optimize human-machine interface(HMI) between operators and their equipment on the basis of physical, physiological and cognitive aspects. However, the HMI design for MCR is not found to be sufficient to maximize operators' performance since the operators in the MCR experience excessive stress due to the environmental factors such as inappropriate interiors and illumination. Therefore, well-designed environment of the MCR may be equally important to improve human performance in the MCR. The objectives of the study are two-fold: (1) to propose an interior design of SHIN-KORI 1 2 for pleasant and comfortable working environments, and (2) to design indirect lighting system to enhance visibility and productivity. The human factors engineering checklists were developed to examine whether or not the proposed human-environment design for SHIN-KORI 1 2 satisfies the regulations and guidelines presented by NUREG-0700 Revision 1. The implications of the human-environment design are discussed in detail.

• Nuclear Engineering and Technology
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• v.54 no.11
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• pp.4195-4208
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• 2022

In this study, operator habitability was numerically evaluated in the event of a fire at the main control bench board (MCB) in a reference main control room (MCR). It was investigated if evacuation variables including hot gas layer temperature (HGLT), heat flux (HF), and optical density (OD) at 1.8 m from the MCR floor exceed the reference evacuation criteria provided in NUREG/CR-6850. For a fire model validation, the simulation results of the reference MCR were compared with existing experimental results on the same reference MCR. In the simulation, various input parameters were applied to the MCB panel fire scenario: MCR height, peak heat release rate (HRR) of a panel, number of panels where fire propagation occurs, fire propagation time, door open/close conditions, and mechanical ventilation operation. A specialized-average HRR (SAHRR) concept was newly devised to comprehensively investigate how the various input parameters affect the operator's habitability. Peak values of the evacuation variables normalized by evacuation criteria of NUREG/CR-6850 were well-correlated as the power function of the SAHRR for the various input parameters. In addition, the evacuation time map was newly utilized to investigate how the evacuation time for different SAHRR was affected by changing the various input parameters. In the previous studies, it was found that the OD is the most dominant variable to determine the MCR evacuation time. In this study, however, the evacuation time map showed that the HF is the most dominant factor at the condition of without-mechanical ventilation for the MCR with a partially-open false ceiling, but the OD is the most dominant factor for all the other conditions. Therefore, the method using the SAHRR and the evacuation time map was very useful to effectively and comprehensively evaluate the operator habitability for the various input parameters in the event of MCB fires for the reference MCR.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.1
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• pp.49-57
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• 2005

ATM Form has defined the guaranteed frame rate (GFR) service to provide minimum cell rate (MCR) guarantees for TCP traffic in ATM networks and allow it to fairly share residual bandwidth. GFR switch implementation consists of the frame-based generic cell rate algorithm (F-GCRA) and a frame forwarding mechanism. The F-GCRA identifies frames that are eligible for an MCR guarantee. The frame forwarding mechanism buffers cells at a frame unit according to information provided by the F-GCRA and forwards the buffered cells to an output port according to its scheduling discipline. A simple GFR mechanism with shared buffer with a global threshold is a feasible implementation mechanism, but has been known that it is insufficient to guarantee the MCR. This paper has estimated performance of GFR service for TCP traffic over ATM switches with the simple FIFO-based mechanism

• The Korea Journal of Herbology
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• v.29 no.4
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• pp.1-8
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• 2014

Objectives : The root bark of Morus alba L. (Mori Cortex Radidus; MCR) has been traditionally used to reduce heat from the lungs, soothe asthma, and edema and to promote urination. In this study, we investigated the effect of MCR ethanol extract on ovalbumin (OVA)-induced allergic asthma in mice. Methods : Mice were sensitized at day 0, 7 and 14 with 0.2% OVA and then airway challenged at day 21, 23, 25, 27 and 29 to induce allergic asthma. MCR extracts at doses of 50 and 100 mg/kg body weight (bw) were orally administered during OVA challenge once per a day. The levels of allergic mediators such as histamine, OVA-specific IgE, IFN-${\gamma}$ and IL-4 were measured in the sera of mice by ELISA. The histopathological change of lung tissues was observed with hematoxylin and eosin (H&E) staining. Results : MCR extract significantly decreased not only the serum levels of histamine, OVA-specific IgE, and IL-4 compared with those of OVA control group, but significantly increased the serum level of IFN-${\gamma}$. In H&E staining, MCR extract inhibited the infiltration of inflammatory cells and bronchiolar damage with epithelial thickening in lung tissues of OVA-induced asthma mice. Conclusions : These results indicate that MCR extract inhibits lung damage by asthma through regulating the allergic immune response, suggesting that MCR may be used as a useful agent for the treatment of allergic asthma.

• Journal of Physiology & Pathology in Korean Medicine
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• v.17 no.4
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• pp.905-913
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• 2003

Oriental medicine explains aging as the weakening of Kidney-ai, and Kidney-strengthening herbal medicines such as Yukmijihwang-tang have been studied for anti-aging effects. In Western Medicine, the hypothesis that reactive oxidant species(ROS) contribute to the aging process is generally accepted. It has been reported that Moutan Cortex Radicis extract (MCR) was the most effective constituent of Yukmijihwang-tang in decreasing ROS production in oxidative-stressed cells. The purpose of this study is to confirm the anti-oxidant effect of MCR on PC12 cells, the expression of Heme oxygenase (HO), Macrophage migradon inhibitory factor (MIF), Catechol-O-methyltransferase (COMT) using real time RT PCR. PC12 cells were treated without or with hydrogen peroxide in the presence or absence of MCR using MTS assay. Hydrogen peroxide decreased the viability of PC12 cells by 53% and MCR did not influence that of stressed PC 12 cells irrespective of dose or incubation period. However, MCR showed an inhibitory effect on production of ROS in stressed cells, both dose and incubation time dependently. In particular, 1 ㎎/㎖ of MCR for 24 h culture almost returned to normal level. In the quantiation of anti-aging related gene expression, MCR at 1 ㎎/㎖ increased the expression of HO by 370%, MIF by 180% and COMT by 280% through real time RT PCR. In conclusion, MCR treatment protected PC12 cells from hydrogen peroxide and decreased ROS production and enhanced anti-oxidative gene expression such as HO, COMT and MIF, which suggests that MCR is involved in controlling anti-aging of nerve cells through elimination of cytotoxic stimuli.