• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4551-4559
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• 2022

The aim of this research is to analyze the characteristics of a core melt discharged from the reactor vessel and the spreading behavior the core melt in the reactor cavity of the SMART. First, a severe accident sequence under conservative conditions is simulated by the MELCOR code to obtain the conditions for an analysis of the spreading behavior and coolability of the ex-vessel melt. Second, the spreading behavior and coolability of the ex-vessel melt are analyzed by the MELTSPREAD code. The level, temperature, and pressure of the water in the cavity as well as the temperature, mass, composition, and discharge velocity of the melt were utilized to construct the ex-vessel analysis. The melt spread only to part of the cavity, and that the height of the corium in a static state was less than 25 cm. The characteristics of a small modular reactor on the spreading behavior and coolability of melt were analyzed. In the SMART, the amount of melt discharged into the cavity is relatively small and the area of the cavity is sufficiently large when compared to a high-power pressurized water reactor. It was found that the coolability of an ex-vessel core melt can be sufficiently secured.

• Nuclear Engineering and Technology
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• v.55 no.1
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• pp.144-155
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• 2023

The core catcher is used as a passive safety system in new generation nuclear power plants to create a space in the containment for the placing and cooling of the molten corium under various severe accidents. This research investigates the role of the core catcher in the VVER-1000 reactor containment system in mitigating the effects of core meltdown under various severe accidents within the context of the Ex-vessel Melt Retention (EVMR) strategy. Hence, a comparison study of three severe accidents is conducted, including Station Black-Out (SBO), SBO combined with the Large Break Loss of Coolant Accident (LB-LOCA), and SBO combined with the Small Break Loss of Coolant Accident (SB-LOCA). Numerical comparative simulations are performed for the aforementioned scenario with and without the EX-vessel core-catcher. The results showed that considering the EX-Vessel core catcher reduces the amount of hydrogen by about 18.2 percent in the case of SBO + LB-LOCA, and hydrogen production decreases by 12.4 percent in the case of SBO + SB-LOCA. Furthermore, in the presence of an EX-Vessel core-catcher, the production of gases such as CO and CO2 for the SBO accident is negligible. It was revealed that the greatest decrease in pressure and temperature of the containment is related to the SBO accident.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.1
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• pp.129-137
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• 2023

According to a continuous attempts to manipulate content on portal sites using automated programs, a Naver, one of a portal site from Korea, is also trying to secure and analyze the programs to respond to the attempts. However, since some of the programs are secured by obfuscation tools, it is necessary to develop de-obfuscation technique. In this paper, we analyze a ConfuserEx, which occupied high percentage from obfuscation tools that applied to obtained programs, and propose an automated tool for de-obfuscating to save time for unpacking.

• Journal of the Korean Society of Visualization
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• v.21 no.1
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• pp.12-17
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• 2023

Aortic valve stenosis is a heart valve disease caused by the accumulation of calcium in the valve, which can divide into tricuspid aortic valve (TAV) stenosis and bicuspid aortic valve (BAV) stenosis depending on the shape of natural valve. In this study, pig heart-based TAV and BAV ex vivo models were fabricated, and the flow characteristics behind a valve were analyzed using 4D flow MRI. Flow behind normal TAV was uniformly distributed, while BAV asymmetrically opened with an eccentric strong jet. Especially, BAV ex vivo model exhibited a secondary flow in the region where the valve closed. In addition, BAV had a 26% higher peak velocity while maintaining similar stroke volume compared with normal TAV. This study would be helpful for understanding the flow characteristics for BAV AS patients.

• Educational Technology International
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• v.17 no.2
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• pp.203-228
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• 2016

This study was designed to determine the factors affecting learner satisfaction and examine the relationships of these factors in mobile learning linked to pre-existing e-learning in universities. In the structural model used, three mobile learning quality factors are the endogenous variables, namely, system quality (SYQ), information quality (INQ) and service quality (SEQ) perceived by students, and learner satisfaction (LS), whereas students' self-efficacy (SE) and experience (EX) in mobile learning are the exogenous variables. The subjects were 900 students who registered for mobile learning courses offered by a private university in Seoul, Korea. The results indicated that SE in mobile learning had positive effects on SYQ, INQ, and SEQ. Furthermore, SE influenced LS when analyzed without quality factors as parameters. Mobile learning EX directly affected INQ, but not SYQ or SEQ. EX likewise had a direct effect on LS when analyzed without quality factors as parameters. Meanwhile, both SYQ and INQ showed a positive effect on LS, but not SEQ. SE and EX affected LS indirectly when SYQ and INQ were used as parameters. This study addresses the importance of increasing SE, EX, SYQ, and INQ to increase LS in mobile learning in universities

• Journal of Life Science
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• v.22 no.4
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• pp.516-523
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• 2012

The purpose of this study was to investigate the effect of exercise and/or L-arginine on abdominal fat, IGF-1 on GH/IGF-1 axis, fibrinogen, and PAI-1 in aged and obese rats. Male Sprague-Dawley rats were treated with a D-galactose aging inducing agent (50 mg/kg) given intraperitoneally for 12 weeks. Thirty-two male Sprague-Dawley rats were treated and divided into four groups: aging-high fat diet group (AG+HF), AG+HF with L-arginine intake group (AG+LA), AG+HF with exercise group (AG+EX), and AG+EX with L-arginine intake group (AG+LA+EX). The experimental rats underwent treadmill training (60 min/day, 6 days/week at 0% gradient) for 12 weeks. L-arginine was given orally (150 mg/kg/day) for 12 weeks. After the experiment, blood was collected from the left ventricle and abdominal fat was extracted. The results showed that GH was significantly increased in AG+EX and AG+AL+EX. IGF-1 was significantly increased in both the AG+AL+EX and AG+EX group ($p$<0.05), while fibrinogen and PAI-1 were not significantly different among the groups. Abdominal fat was significantly decreased in the AG+LA, AG+EX, and AG+LA+EX groups ($p$<0.05) compared with the AG+HF group. In conclusion, this study suggests that exercise alone or L-arginine alone or a combination not only increases the GH and IGF-1 concentration, but also decreases the abdominal fat mass.

• Journal of the Korean Society of Food Science and Nutrition
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• v.42 no.8
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• pp.1197-1203
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• 2013

This study investigated the effects of endurance exercise and ginsenoside $Rb_1$ on AMP-activated protein kinase (AMPK), phosphatidylinositol 3-kinase (PI3K) protein expression and glucose uptake in the skeletal muscle of rats. A total of 32 rats were randomly divided into four groups: CON (Control group, n=8), Ex (Exercise group; 25 m/min for 1 h, 6 days/week, 2 weeks, n=8), $Rb_1$ (Ginsenoside $Rb_1$ group; n=8), and $Rb_1/Ex$ ($Rb_1$+Exercise group, n=8). The $Rb_1$ and $Rb_1/Ex$ groups were incubated in ginsenoside $Rb_1$ (KRBP buffer, $100{\mu}g/mL$) for 60 min after a 2-week experimental treatment. After 2 weeks, the expression of phosphorylated $AMPK{\alpha}$ $Thr^{172}$, total $AMPK{\alpha}$, the p85 subunit of PI3K, pIRS-1 $Tyr^{612}$, and pAkt $Ser^{473}$ were determined in the soleus muscle. Muscle glucose uptake was measured using 2-deoxy-D-[$^3H$] glucose in epitroclearis muscle. Muscle glucose uptake was significantly higher in the three experimental groups (Ex, $Rb_1$, $Rb_1/Ex$) compared to the CON group (P<0.05). The expression of $tAMPK{\alpha}$ and $pAMPK{\alpha}$ $Thr^{172}$ was significantly higher in the Ex, $Rb_1$, and $Rb_1/Ex$ groups compared to the CON group (P<0.05). The expression of pAkt $Ser^{473}$ was significantly higher in the $Rb_1$ group compared to the CON and EX groups. However, the expression of pIRS-1 $Tyr^{612}$ and the p85 subunit of PI3K were not significantly different between the four groups. Overall, these results suggest that ginsenoside $Rb_1$ significantly stimulates glucose uptake in the skeletal muscle of rats through increasing phosphorylation in the AMPK pathway, similar to the effects of exercise.

• Journal of Life Science
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• v.23 no.12
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• pp.1436-1444
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• 2013

To improve the functionality of black garlic drinks, black garlic extract (5%) and five herb extracts (1%) were mixed in 70:30 (v/v) ratios as BHF1, and BHF2 was prepared using a 3X concentration of BHF1. After the black garlic and herb formulas (BHFs) were administered over the course of five weeks in rats by interval running training, the lipid profiles and the antioxidant enzyme activities were tested. The total phenolic content of the BHFs were significantly higher in BHF2 than they were in BHF1, and their antioxidant activities were dependent upon the total phenolic content. No significant difference was found in the total serum protein levels among the rats in the Ex-con group by interval running training and the rats in the BHFs-fed groups. However, the albumin level was significantly higher in the Ex-BHF2 to Ex-con group. AST and ALT activities significantly decreased in the BHFs-fed groups compared to the Ex-con group. In terms of changes in the serum lipid profiles, no significant difference was found between the specimens that underwent interval running training and those that did not undergo interval running training. Triglyceride levels, total cholesterol, LDL-C, and HTR levels in the serum were significantly decreased in the Ex-BHF2 to Ex-con group. No significant difference was found in the total lipid levels in the livers of the BHFs-fed groups and the Ex-con group. The triglyceride levels and total cholesterol levels in the Ex-BHF2 group were significantly lower compared to another group. Hepatic catalase activity was significantly increased in the Ex-BHF2 group, but SOD and GSH-px activities were significantly increased as the concentration of the BHF. The antioxidant enzyme activities by supplementation of BHFs increased; thus, three intakes of BHF each day could improve antioxidant status against different types of oxidative stress.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2182-2191
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• 2011

Postmortem evaluation through the dictionary and the lack of points for the wrong strategy to respond to the avoid the prediction is important. However, the prevailing system of ex post facto assessment of postmortem simply does not have statistical figures to be provided only for the conditions. Thus, in this study, rail business is mainly evaluation procedures and evaluation of the verification system of ex post facto evaluation as to the issue, do not improve.

• Nuclear Engineering and Technology
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• v.38 no.1
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• pp.1-10
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• 2006

The interaction and mixing of high-temperature melt and water is the important technical issue in the safety assessment of water-cooled reactors to achieve ultimate core coolability. For specific advanced light water reactor (ALWR) designs, deliberate mixing of the core-melt and water is being considered as a mitigative measure, to assure ex-vessel core coolability. The paper provides the background of past experiments as well as key fundamentals that are needed for melt-water interfacial transport phenomena, thus enabling the development of innovative safety technologies for advanced LWRs that will assure ex-vessel core coolability.