• Nuclear Engineering and Technology
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• v.54 no.10
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• pp.3745-3765
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• 2022

The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20-70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.

• Journal of Korean Academy of Nursing
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• v.50 no.4
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• pp.621-630
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• 2020

Purpose: This study was aimed to evaluate the external validity of a carbapenem-resistant Enterobacteriaceae (CRE) acquisition risk prediction model (the CREP-model) in a medium-sized hospital. Methods: This retrospective cohort study included 613 patients (CRE group: 69, no-CRE group: 544) admitted to the intensive care units of a 453-beds secondary referral general hospital from March 1, 2017 to September 30, 2019 in South Korea. The performance of the CREP-model was analyzed with calibration, discrimination, and clinical usefulness. Results: The results showed that those higher in age had lower presence of multidrug resistant organisms (MDROs), cephalosporin use ≥ 15 days, Acute Physiology and Chronic Health Evaluation II (APACHE II) score ≥ 21 points, and lower CRE acquisition rates than those of CREP-model development subjects. The calibration-in-the-large was 0.12 (95% CI: - 0.16~0.39), while the calibration slope was 0.87 (95% CI: 0.63~1.12), and the concordance statistic was .71 (95% CI: .63~.78). At the predicted risk of .10, the sensitivity, specificity, and correct classification rates were 43.5%, 84.2%, and 79.6%, respectively. The net true positive according to the CREP-model were 3 per 100 subjects. After adjusting the predictors' cutting points, the concordance statistic increased to .84 (95% CI: .79~.89), and the sensitivity and net true positive was improved to 75.4%. and 6 per 100 subjects, respectively. Conclusion: The CREP-model's discrimination and clinical usefulness are low in a medium sized general hospital but are improved after adjusting for the predictors. Therefore, we suggest that institutions should only use the CREP-model after assessing the distribution of the predictors and adjusting their cutting points.

• Journal of Korean Society for Quality Management
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• v.33 no.1
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• pp.83-87
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• 2005

For the count response we normally consider Poisson regression model. However, the conventional fitting algorithm for Poisson regression model is not reliable at all when the response variable is measured with sizable contamination. In this study, we propose an alternative fitting algorithm that is resistant to outlying values in response and report a case study in semiconductor industry.

• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.911-916
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• 2012

Recently, antibiotic resistant genes (ARGs) in the environment are emerging as pollutants, since these genetic contaminants can eventually be transferred to human pathogens. The aim of this study was to develop the experimental model of antibiotic resistant gene (ARG) plasmid transfer as a function of various environmental conditions. For this purpose, the multi drug resistant plasmid pB10, which is known to be originally isolated from a wastewater treatment plant, was selected as a model transfer plasmid and Escherichia coli $DH5{\alpha}$ containing pB10 was used as a model donor. Pseudomonas aeruginosa, an opportunistic pathogen, was selected as the recipient for the conjugation experiment. When the donor and recipient were exposed to various stressors including antibiotics and heavy metal as a function of the concentrations (10, 100 and, 1000 ppb), statistically increased plasmid transfer rate was observed at a concentration of 10 ppb of tetracycline and sulfamethoxazole compared to control (no antibiotic exposure). Accordingly, the developed experimental ARG model by various stressor is a promising tool for evaluating the dissemination of ARGs by micro-contaminants in aquatic environment.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.133-140
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• 2011

High strength concrete used for large structures is vulnerable to fire due to explosive spalling when it is heated. Recently, various research is conducted to enhance the fire-resistance of the high strength concrete by reducing the explosive spalling at the elevated temperature. In this study, a heat transfer analysis model is proposed for a fiber-embedded fire-resistant high strength concrete. The material model of the fire-resistant high strength concrete is selected from the calibrated material model of a high strength concrete incorporating thermal properties of fibers and physical behavior of internal concrete at the elevated temperature. By comparing the simulated results using the calibrated model with the experimental results, the heat transfer model of the fiber-embedded fire-resistant high strength concrete is proposed.

• Journal of Microbiology and Biotechnology
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• v.33 no.10
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• pp.1281-1291
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• 2023

Infectious diseases caused by drug-resistant Escherichia coli (E. coli) pose a critical concern for medical institutions as they can lead to high morbidity and mortality rates. In this study, amygdalin exhibited anti-inflammatory and antioxidant activities, as well as other potentials. However, whether it could influence the drug-resistant E. coli-infected cells remained unanswered. Amygdalin was therefore tested in a cellular model in which human macrophages were exposed to resistant E. coli. Apoptosis was measured by flow cytometry and the lactate dehydrogenase (LDH) assay. Western immunoblotting and quantitative reverse-transcription polymerase chain reaction (qRT-PCR) were used to quantify interleukin-18 (IL-18), interleukin-1β (IL-1β), and interleukin-6 (IL-6). The production of reactive oxygen species (ROS) in macrophages was detected by ROS kit. The expression of pan-apoptotic proteins in macrophages was measured by qRT-PCR and Western immunoblotting. Drug-Resistant E. coli inhibited cell viability and enhanced apoptosis in the cellular model. In cells treated with amygdalin, this compound can inhibit cell apoptosis and reduce the expression of pro - inflammatory cytokines such as IL-1β, IL-18 and IL-6. Additionally, it decreases the production of PANoptosis proteins, Furthermore, amygdalin lowered the levels of reactive oxygen species induced by drug-resistant E. coli, in cells, demonstrating its antioxidant effects. Amygdalin, a drug with a protective role, alleviated cell damage caused by drug-resistant E. coli in human macrophages by inhibiting the PANoptosis signaling pathway.

• Journal of Microbiology and Biotechnology
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• v.31 no.10
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• pp.1383-1392
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• 2021

Carbapenem-resistant Enterobacteriaceae (CRE) that produce Klebsiella pneumoniae carbapenemase are increasingly reported worldwide and have become more and more resistant to nearly all antibiotics during the past decade. The emergence of K. pneumoniae strains with decreased susceptibility to carbapenems, which are used as a last resort treatment option, is a significant threat to hospitalized patients worldwide as K. pneumoniae infection is responsible for a high mortality rate in the elderly and immunodeficient individuals. This study used Lactobacillus fermentum as a candidate probiotic for treating CRE-related infections and investigated its effectiveness. We treated mice with L. fermentum originating from the vaginal fluid of a healthy Korean woman and evaluated the Lactobacilli's efficacy in preventive, treatment, nonestablishment, and colonization mouse model experiments. Compared to the control, pre-treatment with L. fermentum significantly reduced body weight loss in the mouse models, and all mice survived until the end of the study. The oral administration of L. fermentum after carbapenem-resistant Klebsiella (CRK) infection decreased mortality and illness severity during a 2-week observation period and showed that it affects other strains of CRK bacteria. Also, the number of Klebsiella bacteria was decreased to below 5.5 log₁₀ CFU/ml following oral administration of L. fermentum in the colonization model. These findings demonstrate L. fermentum's antibacterial activity and its potential to treat CRE infection in the future.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.474-478
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• 2004

Based on the recent laboratory experiments (Kim et al. 2004), comparisons of caisson sliding distance are made between the computations and experiments. The time history model of wave force, which is proposed by Tanimoto et al. (1996), is modified in the standing wave part of horizontal and uplift wave forces because of the overestimation of the time history model. The comparison between experimental and computational sliding distance has showed that the caisson tilting increases the resistant force to the horizontal sliding. Therefore, a titling resistant force, which is caused by caisson tilting, is introduced into computation of sliding distance.

• Wind and Structures
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• v.1 no.1
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• pp.67-75
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• 1998

Tiger Gate Bridge, a steel suspension bridge with a main span of 888 m and a stiffening box girder, is located at the Pearl River Estuary, Guangdong Province, one of the typhoon-prone area in China. Focusing on the developing of the full aeroelastic model of the bridge and simulation of the wind field of the bridge site in a large boundary wind tunnel at Tongji University, Shanghai, China, some main results about the wind resistant properties of the bridge including aerodynamic instability, buffeting responses both being in operation and erection stages by using of a full aeroelastic model wind tunnel testing are introduced. Some of analytical approaches to those aerodynamic behaviours are also presented, and compared with experimental data of the testing.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.22 no.3
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• pp.268-276
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• 2015

Purpose: The purpose of this study was to identify factors which influence the management of MultiDrug -Resistant Organisms (MDROs) by nurses in Intensive Care Units (ICUs). Methods: Data were collected from December 8 to 20, 2013 and participants were 163 ICU nurses working in one general hospital. The Health Belief Model tool and knowledge and management of MDROs infection tools were used in the study. Descriptive statistics, t-test, analysis of variances, Pearson correlation coefficients and multiple regression were used to analyze the data. Results: Knowledge, perceived susceptibility, and perceived benefits had a significant influence on MRSA (Methicillin Resistant Staphylococcus Aureus,) and MDRAB (Multidrug Resistant Acinetobacter Baumannii) infection management when all the other variables were considered. Significant variable which had influence on VRE (Vancomycin Resistant Eenterococci) infection management were perceived susceptibility and perceived benefits. Conclusion: Perceived susceptibility and perceived benefits had significant influence on MDROs infection management. Emphasis needs to be on the perceived susceptibility and perceived benefits of MDROs infection management when providing an educational program for ICU nurses.