• Geomechanics and Engineering
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• 제11권3호
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• pp.421-438
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• 2016

Explosions inside transportation tunnels might result in failure of tunnel structures. This study investigated the failure mechanisms of circular cast-iron tunnels in saturated soil subjected to medium internal blast loading. This issue is crucial to tunnel safety as many transportation tunnels run through saturated soils. At the same time blast loading on saturated soils may induce residual excess pore pressure, which may result in soil liquefaction. A series of numerical simulations were carried out using Finite Element program LS-DYNA. The effect of soil liquefaction was simulated by the Federal Highway soil model. It was found that the failure modes of tunnel lining were differed with different levels of blast loading. The damage and failure of the tunnel lining was progressive in nature and they occurred mainly during lining vibration when the main event of blast loading was over. Soil liquefaction may lead to more severe failure of tunnel lining. Soil deformation and soil liquefaction were determined by the coupling effects of lining damage, lining vibration, and blast loading. The damage of tunnel lining was a result of internal blast loading as well as dynamic interaction between tunnel lining and saturated soil, and stress concentration induced by a ventilation shaft connected to the tunnel might result in more severe lining damage.

• 동의생리병리학회지
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• 제17권2호
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• pp.467-475
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• 2003

This studt was investigated to prove the effect of GMYM on the brain damage. The results were as follows; 1. GMYM showed significantly inhibitory effect on LDH release by NMDA. AMPA and Kinate. 2. GMYM showed significantly inhibitory effect on LDH release by BSO and Fe2+. 3. GMYM decreased coma duration time in a infatal dose of KCN and showed 30% of survival rate in a fatal dose. 4. GMYM showed improvement of forelimb and hindlimb test after MCA occulusion in neurological exemination. 5. GMYM decreased ischemic area and edema incited by the MCA blood flow block. These results indicate that GMYM can be used in the brain damage sujected to brain ischemia. Further study will be needed about the functional mechanism and etc.

• 동의생리병리학회지
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• 제17권3호
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• pp.728-737
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• 2003

This study was investigated to prove the effect of GMGHT on the gultamate receptor, free radical and brain damage in rats sujected to Brain Ischemia The results were as follows; 1, GMGHT showed significant inhibitory effect of GMGHT on LDH release induced by NMDA, AMPA, and kinate. 2. GMGHT showed significant inhibitory effect of GMGHT on LDH release induced by BSO and Fe/sup 2+/. 3. GMGHT decreased coma duration time in a infatal dose of KCN and showed 30% of survival rate in a fatal dose. 4. GMGHT decreased ischemic area and edema incited by the MCA blood flow block. 5. GMGHT showed improvement of forelimb and hindlimb test after MCA occulusion in neurological exemination. 6. GMGHT showed no significant change after MCA occulusion in pathological observation as normal group. These results indicate that GMGHT can be used in the brain damage sujected to Brain Ischemia. Further study will be needed about the functional mechanism and etc.

• 대한한의학회지
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• 제25권3호
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• pp.32-44
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• 2004

Objectives : This study was undertaken to prove the effect of GSHT on the glutamate receptor, free radical and brain damage in rats subjected to brain ischemia Methods : Levels of cultured cortical neuron death caused by toxic chemicals were measured by LDH release assay. Neuroprotective effects of GSHT on brain tissues were examined in vivo by ischemic model of middle cerebral artery (MCA) occlusion. Results : GSHT showed significant inhibitory effect on LDH release induced by NMDA-kinate-Fe/sup 2+/. GSHT remarkably decreased coma duration time in a nonfatal dose of KCN and showed higher survival rate in a fatal dose. GSHT remarkably decreased ischemic area and edema induced by the MCA blood flow block. GSHT showed high improvement of forelimb and hind limb test after MCA occlusion in neurological examination. GSHT showed no significant change after MCA occlusion in pathological observation of the normal group. Conclusions : These results indicate that GSHT can be used to treat the brain damage caused by brain ischemia. Further study will be needed about the functional mechanism, etc.

• 한국안전학회지
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• 제36권3호
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• pp.66-73
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• 2021

This report documents the results of an at-power internal events Level 1 Probabilistic Safety Assessment (PSA) for a Korea research reactor (KRR). The aim of the study is to determine the accident sequences, construct an internal level 1 PSA model, and estimate the core damage frequency (CDF). The accident quantification is performed using the AIMS-PSA software version 1.2c along with a fault tree reliability evaluation expert (FTREX) quantification engine. The KRR PSA model is quantified using a cut-off value of 1.0E-15/yr to eliminate the non-effective minimal cut sets (MCSs). The final result indicates a point estimate of 4.55E-06/yr for the overall CDF attributable to internal initiating events in the core damage state for the KRR. Loss of Electric Power (LOEP) is the predominant contributor to the total CDF via a single initiating event (3.68E-6/yr), providing 80.9% of the CDF. The second largest contributor is the beam tube loss of coolant accident (LOCA), which accounts for 9.9% (4.49E-07/yr) of the CDF.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.543-546
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• 1999

The purpose of the present study is to identify the damage characteristics of concrete structures due to cracking by employing the acoustic emission techniques. A comprehensive experimental study has been done. The cracking damages under tensile and flexural loadings have been identified and the bond damage between steel and concrete have been also characterized. It is seen that the amplitudes and energy level of AE events is found to be smaller for bond cracking damages and larger for tensile cracking damages. The characteristic equations of the AE events for various cracking damages have been proposed based on the present test data. The internal microcracks are progressively developed ahead of a visible actual crack and the present study clearly exhibits thses damage mechanism for various types of cracking in concrete. The present study provides very useful data which can be used to identify the various types of cracking damages in concrete structures. This will allow very efficient maintenance of concrete structures through monitoring of internal cracking based on acoustic emission.

• 대한한방내과학회지
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• 제25권2호
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• pp.214-223
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• 2004

The study examines the anti-cancer effects of the hot water extract of Mylabris phalerata(MP) using SNU-C5 cell lines. Microscopic analysis showed that 12 hours after MP treatment, the number of dead cells increased prominently. Significant cell death was observed 12, 24, and 48 hours after MP treatment through trypan blue exclusion testing. This suggests that MP is time-dependently cytotoxic. Mitotracker Red CMXRos staining and flowcytometry revealed that MP decreased mitochondrial membrane potentials. The absence of peaks on PI staining showed that DNA damage occurred in MP treated cells. Taken together, measurements suggest that MP has a strong anti-cancer effect on SNU-5 cell lines, and that this is likely to be due to the destruction of mitochondria and DNA damage.

• International Journal of Aerospace System Engineering
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• 제2권2호
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• pp.19-23
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• 2015

This work deals with the study of buckling and post buckling characteristics of laminated composite plates with and without localized regions of damage. The need of a detailed study on Finite Element Analysis of buckling and post buckling of laminated composite structures considering various aspects enhances the interest among researchers. Mathematical formulation is developed for damaged composite plates using a finite element technique based on Inverse Hyperbolic Shear Deformation Theory. This theory satisfies zero transverse shear stresses conditions at the top and bottom surfaces of the plate and provides a non-linear transverse shear stress distribution. Damage modeling is done using an anisotropic damage formulation, which is based on the concept of stiffness change. The structural elements are subjected to in-plane loading. The computer program is developed in MATLAB environment. The numerical results are presented after through validation of developed finite element code. The effect of damage on buckling and post buckling has been carried out for various parameters such as amount of percentage of damaged area, damage intensity, etc. The results show that the presence of internal flaws will significantly affect the buckling characteristics of laminated composite plates. The outcomes and remarks from this work will assist to address some key issues concerning composite structures.

• 전자공학회논문지A
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• 제31A권12호
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• pp.64-70
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• 1994

In this paper, we inverstigated how a parricular internal inverter circuit, which is located far from the input protection in CMOS DRAM, can be easily damaged by external ESD stress, while the protection circuit remains intact. It is shown in a mega bit DRAM that the internal circuit can be safe from ESD by simply improving the input protection circuit. An inverter, which consists of a relatively small NMOSFET and a very large PMOSFET, is used to speed up DRAMs, and the small NMOSFET is vulnerable to ESD in case that the discharge current beyond the protection flows through the inverter to Vss or Vcc power lines on chip. This internal circuit damage can not be detected by only measuring input leakage currents, but by comparing the standby and on operating current before and after ESD stressing. It was esperimentally proven that the placement of parasitic bipolar transistor between input pad and power supply is very effective for ESD immunity.

• 대한한방내과학회지
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• 제28권1호
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• pp.68-79
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• 2007

Objectives : The purpose of our study was to investigate the effects of Chungganhaeju-tang (Qingganjiejiu-tang) on alcoholic liver damage by applying proteomics. Materials and Methods : Sprague-Dawley rats were used in this experiment; the rats were divided into a control group, alcohol group and Chungganhaeju-tang + alcohol group. Ethanol was orally administered twice a day for 4 weeks to the alcohol group. Water without ethanol was administered twice a day for 4 weeks to the control group. Ethanol + Chungganhaeju-tang extract was orally administered twice a day for 4 weeks to the Chungganhaeju-tang + alcohol group. The livers of each group were processed and we investigated histology, OxyBlot, 2-dimensional electrophoresis, and western blot of liver of each group. Results : In the histological findings of the liver, the alcohol group showed portal fibrosis with a few septa or without septa. The Chungganhaeju-tang + alcohol group showed no fibrosis or portalfibrosis without septa. In the OxyBlot finding, Chungganhaeju-tangprevented liver damage by oxidation. In the 2-dimensional electrophoresis finding, formiminotransferase cyclodeaminase (FTCD), glucose regulated protein, 58 kDa (GRP58K), aryl sulfotransferase, sulfotransferase family 1A, member 2, similar to acyl-coenzyme A oxidase-like, and catalase were changed. Conclusion : Chungganhaeju-tangexerts an inhibitory effect against the fibrosis and oxidation induced by alcohol in rat liver cell, and some proteins induced by alcohol were changed by Chungganhaeju-tang.