• Journal of computational fluids engineering
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• v.14 no.2
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• pp.9-18
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• 2009

The cargo containment system (CCS) for ships carrying cryogenic fluid consists of at least two levels of barriers and insulation layers. It is because, even though there is a small amount of leak through the primary barrier, the liquid tight secondary barrier blocks further leakage of the cryogenic fluid. However, once the secondary barrier is damaged, it is highly possible that the leaked cryogenic fluid flows through the flat joint made of glass wool and reaches the inner hull of the ship. The primary objective of the present study is to investigate the influence of the damage extent in the secondary barrier on the amount of leaked cryogenic fluid reaching the inner hull and the temperature distribution there. Simulation results using a computational fluid dynamics tool were compared with the experimental data for the leaked cryogenic fluid flow and evaporation in the secondary insulation layer. The experimental and computational results suggest that, unless there is a massive leak, the cryogenic fluid mostly evaporates in the insulation layer and does not reach the inner hull in the state of liquid.

• Nuclear Engineering and Technology
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• v.52 no.5
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• pp.1051-1065
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• 2020

Safety analysis of nuclear power plant (NPP) especially in accident conditions is a basic and necessary issue for applications and commercialization of reactors. Many previous researches and development works have been conducted. However, most achievements focused on the safety reliability of primary pressure system vessels. Few literatures studied the structural safety of huge concrete structures surrounding primary pressure system, especially for the fourth generation NPP which allows existing of through cracks. In this paper, structural safety reliability of concrete structures of HTR-PM in accidental double-ended break of hot gas ducts was studied by Exceedance Probability Method. It was calculated by Monte Carlo approaches applying numerical simulations by Abaqus. Damage parameters were proposed and used to define the property of concrete, which can perfectly describe the crack state of concrete structures. Calculation results indicated that functional failure determined by deterministic safety analysis was decided by the crack resistance capability of containment buildings, whereas the bearing capacity of concrete structures possess a high safety margin. The failure probability of concrete structures during an accident of double-ended break of hot gas ducts will be 31.18%. Adding the consideration the contingency occurrence probability of the accident, probability of functional failure is sufficiently low.

• Nuclear Engineering and Technology
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• v.54 no.8
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• pp.2933-2940
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• 2022

Approximations such as the delete-term approximation, rare event approximation, and minimal cutset upper bound (MCUB) need to be prudently applied for the quantification of a seismic probabilistic safety assessment (PSA) model. Important characteristics of seismic PSA models indicate that preserving the success branches in a primary seismic event tree is necessary. Based on the authors' experience in modeling and quantifying plant-level seismic PSA models, the effects of applying negate-down to the success branches in primary seismic event trees on the quantification results are summarized along with the following three insights gained: (1) there are two competing effects on the MCUB-based quantification results: one tending to increase and the other tending to decrease; (2) the binary decision diagram does not always provide exact quantification results; and (3) it is identified when the exact results will be obtained, and which combination provides more conservative results compared to the others. Complicated interactions occur in Boolean variable manipulation, approximation, and the quantification of a seismic PSA model. The insights presented herein can assist PSA analysts to better understand the important theoretical principles associated with the quantification of seismic PSA models.

• Nuclear Engineering and Technology
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• v.56 no.4
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• pp.1480-1489
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• 2024

Displacement cascade behaviors of Ti-6Al-4V alloys are investigated using molecular dynamics (MD) simulation. The embedded atom method (EAM) potential including Ti, Al and V elements is modified by adding Ziegler-Biersack-Littmark (ZBL) potential to describe the short-range interaction among different atoms. The time evolution of displacement cascades at the atomic scale is quantitatively evaluated with the energy of primary knock-on atom (PKA) ranging from 0.5 keV to 15 keV, and that for pure Ti is also computed as a comparison. The effects of temperature and incident direction of PKA are studied in detail. The results show that the temperature reduces the number of surviving Frenkel pairs (FPs), and the incident direction of PKA shows little correlation with them. Furthermore, the increasing temperature promotes the point defects to form clusters but reduces the number of defects due to the accelerated recombination of vacancies and interstitial atoms at relatively high temperature. The cluster fractions of interstitials and vacancies both increase with the PKA energy, whereas the increase of interstitial cluster is slightly larger due to their higher mobility. Compared to pure Ti, the presence of Al and V is beneficial to the formation of interstitial clusters and indirectly hinders the production of vacancy clusters.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.8
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• pp.1246-1251
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• 2004

To investigate the effects of plant extracts on the protection against liver damage by $CCl_4$ in rat, two kinds of experiment were performed, firstly by the primary hepatocyte culture and secondly by the animal feeding. The primary hepatocyte culture with the extracts of pine leaf, soybean sprout and mugwort showed significantly low activities (p<0.01∼0.05) of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), indicating an excellent protective effect against liver damage by $CCl_4$. In the second experiment, the microsomal malondialdehyde (MDA) contents of the above same groups were also significantly lower (p<0.01) than the $CCl_4$-treated group without plant extracts, but shiitake showed less effect. Among four kinds of plant extracts, extracts of pine leaf and mugwort showed also much higher activities of the microsomal cytochrome P-450 in comparison to soybean sprout and shiitake. In the test of xanthine oxidase (XOD) activity, all of three groups except shiitake showed significantly low activities (p<0.01). These consistent results in vitro and in vivo suggest that the extracts of pine leaf, soybean sprout and mugwort may have strong protective effects against liver damage induced by the potential toxicants such as $CCl_4$.

• The Journal of Pediatrics of Korean Medicine
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• v.31 no.1
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• pp.43-51
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• 2017

Objectives Hataedock method is a Korean medical therapy which removes fetal toxin by orally administering herbal decoction to neonates. This study was to observe skin damage and anti-inflammatory effect via regulating IL-4 activity in NC/Nga mice which were induced atopic dermatitis (AD)-like skin lesion by Dermatophagoides (D.) farinae after applying Douchi Hataedock method. Methods NC/Nga mice with 3 weeks of gestational age were used. Each 10 mice were allocated to the control group (Ctrl), the AD-induced group (AE), and the group which induced AD after administering Douchi extract (GT). After 4 weeks from administering Douchi extract to the mice, the primary AD was induced by applying D. farinae extract 6 times per week for 3 weeks and then the secondary AD was induced by the same method after 1 week from the primary AD induction. To identify the skin damage and anti-inflammatory effect, we observed LxR, IL-4, Fc ${\varepsilon}$ receptor, substance P, and $NF-{\kappa}B$. Results The GT group showed alleviation of skin injury and decrease in capillary angiogenesis. Stratum corneum damage, epithelial cell hyperplasia, lymphocyte infiltration, and capillary distribution relatively decreased in the GT group. LxR-positive reaction in the GT group were increased by 53% than that of the AE group. IL-4 production, $Fc{\varepsilon}$ receptor activity, and substance P-positive reaction in the GT group were decreased by 82%, 42%, and 82% respectively compare to those of the AE group. $NF-{\kappa}B$-positive reaction in the GT group were decreased by 15% compare to that of the AE group. Conclusions Hataedock method with Douchi extract alleviated AD via reducing inflammatory cytokines secreted at the early stage of AD. Thus, Douchi Hataedock method has a beneficial effect for the prevention and treatment of AD.

• Journal of Sericultural and Entomological Science
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• v.50 no.2
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• pp.93-100
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• 2012

To investigate the effects of Protaetia. brevitarsis extracts on the protection against liver damage by carbon tetrachloride($CCl_4$) in rat, two kinds of experiment were performed, firstly by the primary hepatocyte culture and secondly by the animal feeding. The primary hepatocyte culture with the extracts of P.brevitarsis showed significantly low activities of GPT, bile acid, and bilirubin, indicating an excellent protective effect against liver damage by $CCl_4$. Especially, below molecular weight 1,000 blew the water to have 32.1% recovery degree. In the seconde experiment, serum GPT activity was significantly decreased in water fraction of P. brevitarsis compared to $CCl_4$ treatment by 98.2%. Serum concentration of bile acid and bilirubin were tended to increased by $CCl_4$ treatment, but water fraction of P. brevitarsis and silymarin recovered the level. These consistent results in vitro and in vivo suggest that the extracts of P. brevitarsis may have strong protective effects against liver damage induced by the potential toxicants such as $CCl_4$.

• Journal of the Korean Burn Society
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• v.23 no.2
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• pp.54-59
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• 2020

Purpose: A fourth degree burn is a full-thickness burn of the skin usually accompanied by damage to deep structures and commonly results in extensive damage to surrounding tissues which makes the treatment of the wound difficult. Coverage of these wound using free flap is known to effective but not commonly used. The purpose of our study is to review our experience and suggest early application of free flap surgery. Methods: A retrospective review was performed from 2010 to 2019, on a total of 34 fourth degree burn patients undergone free flap surgery as primary treatment in our hospital. We reviewed the location of the injury, etiology, TBSA (%), Presence of osteomyelitis, flap choice, complications, period of injury to surgery and healing. Results: Using free flap as a primary reconstrcuction, the outcome is satisfactory. The treatment period was shortened, and there was less loss of function due to complications. Also the incidence of osteomyelitis and amputation was significantly low. Conclusion: Applying free flap surgery as soon as possible in fourth degree burns is effective, such as reducing complications such as infection, reducing amputation, shortening treatment period, and preventing severe sequelae.

• Journal of Korean Neurosurgical Society
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• v.67 no.4
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• pp.418-430
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• 2024

Objective : Isoflurane, a widely used common inhalational anesthetic agent, can induce brain toxicity. The challenge lies in protecting neurologically compromised patients from neurotoxic anesthetics. Choline alfoscerate (L-α-Glycerophosphorylcholine, α-GPC) is recognized for its neuroprotective properties against oxidative stress and inflammation, but its optimal therapeutic window and indications are still under investigation. This study explores the impact of α-GPC on human astrocytes, the most abundant cells in the brain that protect against oxidative stress, under isoflurane exposure. Methods : This study was designed to examine changes in factors related to isoflurane-induced toxicity following α-GPC administration. Primary human astrocytes were pretreated with varying doses of α-GPC (ranging from 0.1 to 10.0 µM) for 24 hours prior to 2.5% isoflurane exposure. In vitro analysis of cell morphology, water-soluble tetrazolium salt-1 assay, quantitative real-time polymerase chain reaction, proteome profiler array, and transcriptome sequencing were conducted. Results : A significant morphological damage to human astrocytes was observed in the group that had been pretreated with 10.0 mM of α-GPC and exposed to 2.5% isoflurane. A decrease in cell viability was identified in the group pretreated with 10.0 µM of α-GPC and exposed to 2.5% isoflurane compared to the group exposed only to 2.5% isoflurane. Quantitative real-time polymerase chain reaction revealed that mRNA expression of heme-oxygenase 1 and hypoxia-inducible factor-1α, which were reduced by isoflurane, was further suppressed by 10.0 µM α-GPC pretreatment. The proteome profiler array demonstrated that α-GPC pretreatment influenced a variety of factors associated with apoptosis induced by oxidative stress. Additionally, transcriptome sequencing identified pathways significantly related to changes in isoflurane-induced toxicity caused by α-GPC pretreatment. Conclusion : The findings suggest that α-GPC pretreatment could potentially enhance the vulnerability of primary human astrocytes to isoflurane-induced toxicity by diminishing the expression of antioxidant factors, potentially leading to amplified cell damage.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.419-434
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• 2020

In this study, the damage parameters of Mazars model for KURT (KAERI Underground Research Tunnel) granite are measured form uniaxial compressive and Brazilian tests under the simulated coupled condition of a deep geological disposal. The tests are conducted in three different temperatures (15℃, 45℃, and 75℃) and dry/saturated conditions. Major model parameters such as maximum effective tensile strain (𝜖_d0), A_t, B_t, A_c, and B_c differ from the typical reference values of concrete specimens. This is likely due to the difference in elastic modulus between rock and concrete. It is found that the saturation of specimens causes an increase in value of B_t and B_c while, the rise in temperature increases 𝜖_d0 and B_t and decreases B_c. The damage model obtained from this study will be used as the primary input parameters in the development of coupled Thermo-Hydro-Mechanical Damage numerical model in KAERI.