• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.1
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• pp.9-18
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• 2019

In 2017 Pohang Earthquake, a number of residential buildings with pilotis at their first level were severely damaged. In this study, the results of an analytical investigation on the seismic performance and structural damage of two bearing wall buildings with pilotis are presented. The vibration mode and lateral force-resisting mechanism of the buildings with vertical and plan irregularity were investigated through elastic analysis. Then, based on the investigations, methods of nonlinear modeling for walls and columns at the piloti level were proposed. By performing nonlinear static and dynamic analyses, structural damages of the walls and columns at the piloti level under 2017 Pohang Earthquake were predicted. The results show that the area and arrangement of walls in the piloti level significantly affected the seismic safety of the buildings. Initially, the lateral resistance of the piloti story was dominated mainly by the walls resisting in-plane shear. After shear cracking and yielding of the walls, the columns showing double-curvature flexural behavior contributed significantly to the residual strength and ductility.

• Korean Journal of Agricultural and Forest Meteorology
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• v.13 no.3
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• pp.140-147
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• 2011

We studied the influence of livestock waste leachate on oxidative damage and antioxidative responses in poplar clones in August which increase the demand of antioxidants because of high temperature and high light during this period. We measured ion leakage, antioxidant enzyme activities (APX, GR), and carotenoid contents. Oxidative damage and antioxidative responses by treated livestock waste leachate in poplar clones showed various results. We divided poplar clones into three groups using the criteria based on ion leakage which represent cell damage induced oxidative stress. Eco 28, 62-10, Bonghwa1 and Dorskamp belonged to the first group in which the cell damaged level was lower than that of the control. The results suggest that this group augmented for demand of antioxidative in summer because high concentration of nitrogen induced by treatment of live stock wastes acted as environmental stress. Consequently, they failed to keep up the homeostasis of reactive oxygen species. The second group in which the cell damaged level was similar to that of the control was Suwon, 72-30 and 72-31 clones. Finally, 97-18 clone belonged to the third group in which the cell damaged level was lower than that of the control group. In this case, nitrogen treated by livestock waste leakage decreased oxidative stress. 97-18 clone was the clones with the least damage in summer oxidative stresses treated by livestock waste leakage. These results suggest that the high concentration nitrogen due to the livestock waste leakage can act differently upon the clones. We speculate that the added oxidation damage in the summer (growing season) may have an effect on the total fresh weight and also influence the purification ability for livestock waste leakage. However, further studies are needed for the confirmation.

• Journal of the Earthquake Engineering Society of Korea
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• v.24 no.6
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• pp.293-303
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• 2020

Seismic fragility was assessed for non-seismic reinforced concrete shear walls in Korean high-rise apartment buildings in order to implement an earthquake damage prediction system. Seismic hazard was defined with an earthquake scenario, in which ground motion intensity was varied with respect to prescribed seismic center distances given an earthquake magnitude. Ground motion response spectra were computed using Korean ground motion attenuation equations to match accelerograms. Seismic fragility functions were developed using nonlinear static and dynamic analysis for comparison. Differences in seismic fragility between damage state criteria including inter-story drifts and the performance of individual structural members were investigated. The analyzed building had an exceptionally long period for the fundamental mode in the longitudinal direction and corresponding contribution of higher modes because of a prominently insufficient wall quantity in such direction. The results showed that nonlinear static analyses based on a single mode tend to underestimate structural damage. Moreover, detailed assessments of structural members are recommended for seismic fragility assessment of a relatively low performance level such as collapse prevention. On the other hand, inter-story drift is a more appropriate criterion for a relatively high performance level such as immediate occupancy.

• Journal of Welding and Joining
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• v.9 no.1
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• pp.40-47
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• 1991

The most fatigue tests carried out under the either stress or strain control, but machines and structures had taken variable stress. This variable stress was treated as statistics based on p-type distributions. In this paper, the cumulative fatigue damage of SM45C round bar specimens having a center hole resulting from block loading with p-distributions in rotating bending conditions, is presented. The value of p was changed in the range from 0.25 to 1; 0.25, 0.5, 0.75, 1. The following conclusions were obtained through the constant stress amplitude experiments and the block loading experiments. (1) In constant loading test, fatigue life was affected by cyclic rate. From experimental data, N$_{f}$ (100cpm)/N$_{f}$(3000cpm)equal to 0.56. (2) In case of the cyclic rate 100cpm and 3000cpm, at the high stress amplitude level the crack propagation life N$_{*}$f is longer than the low stress amplitude level. (3) Miner's hypothesis may be valid for p=0.75 and prediction of fatigue life by Haibach's method agree with experimental data well for the case p=0.5, while the modified Miner's method agree with experimental data well for the case p=0.25.5.

• Nutrition Research and Practice
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• v.7 no.5
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• pp.373-379
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• 2013

The consumption of fruits and vegetables that have high polyphenol content has been previously associated with a reduced risk for cardiovascular disease. We investigated the effects of onion peel extract on plasma total antioxidant capacity, lipid peroxidation, and leukocyte DNA damage. This study was a randomized, double-blind, placebo-controlled, crossover trial. Healthy female subjects received either onion peel extract or placebo (dextrin) for two weeks, underwent a 1-week washout period, and then received the other treatment for an additional two weeks. After two weeks of onion peel extract supplementation, the total cholesterol level, low-density lipoprotein cholesterol level, and atherogenic index significantly decreased (P < 0.05). No changes were observed in activities of erythrocyte antioxidant enzymes or levels of lipid peroxidation markers following onion peel extract supplementation. Additionally, no significant difference was found in plasma antioxidant vitamin (retinol, tocopherols, carotenoids, and coenzyme Q10) levels or ex vivo $H_2O_2$-provoked oxidative DNA damage after onion peel extract supplementation. The present interventional study provides evidence of the health benefits of onion peel extract and demonstrates its effects in modulating lipid profiles in healthy young Korean women.

• Journal of Physiology & Pathology in Korean Medicine
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• v.16 no.6
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• pp.1151-1156
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• 2002

This research was done to make the effective prescription and cope with various senile dementia. Sprague-Dawley rats were injured by ibotenic acid to make a damage on learning and memory functions of model rats. At first acquisition test and retention rest were done in the Morris water maze. And to evaluate the effects of the sample drug(GSD) on choline acetyltranferase and acetylcholine esterase, immunoreactive measurement and enzymatic activity measuring were carried out. The ibotenic acid were injected to hippocampus CA1 and CA3 area. Conclusion : GSD improved the learning ability in the acquisition test and memory function in the retention test significantly. And GSD increased the level of ChAT which is synthesizing acetylcholine in CA1 area, and at the same time it increased the level of AChE which is resolving acetylcholine. These results show that GSD improved the cholinergic catabolism and anabolism, and the increment of metabolic activity of cholinergic system. In other words, it contributes to the recovery of damaged learning and memory function by ibotenic acid. So it can be concluded that GSD will be helpful to cholinergic brain damage induced by primary or senile reduction of acetylcholine secretive activity.

• Korean Journal of Environmental Biology
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• v.31 no.3
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• pp.189-191
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• 2013

Mycotoxins such as aflatoxin B1 (AFB1), ochratoxin A (OTA) and zearalenone (ZEA) are widespread contaminants of food and feedstuffs. It is very likely, that humans and animals are always exposed to mixtures of mycotoxins rather than to individual compounds. Therefore, risk assessments should consider mixture toxicity data. In the present study the combination of AFB1, OTA and ZEA was tested for genotoxicity in rat bone marrow and blood leukocytes after 15, 30 and 60 days treatment. The level of DNA damage was determined by the comet assay. The tail intensity and Olive tail moment in leukocytes and bone marrow cells were significantly higher than in controls. At the same time, the level of DNA damage in bone marrow cells was higher than in leukocytes. The data suggests that prolonged exposure to mycotoxins combination through food consumption can induce DNA damage contributing to the harmful effects in vivo.

• Journal of the Korean Society of Safety
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• v.34 no.3
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• pp.102-110
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• 2019

This paper describes the work and results of the preliminary Probabilistic Safety Assessment (PSA) for a research reactor in the design phase. This preliminary PSA was undertaken to assess the level of safety for the design of a research reactor and to evaluate whether it is probabilistically safe to operate and reliable to use. The scope of the PSA described here is a Level 1 PSA which addresses the risks associated with core damage. After reviewing the documents and its conceptual design, eight typical initiating events are selected regarding internal events during the normal operation of the reactor. Simple fault tree models for the PSA are developed instead of the detailed model at this conceptual design stage. A total of 32 core damage accident sequences for an internal event analysis were identified and quantified using the AIMS-PSA. LOCA-I has a dominant contribution to the total CDF by a single initiating event. The CDF from the internal events of a research reactor is estimated to be 7.38E-07/year. The CDF for the representative initiating events is less than 1.0E-6/year even though conservative assumptions are used in reliability data. The conceptual design of the research reactor is designed to be sufficiently safe from the viewpoint of safety.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.33 no.12
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• pp.3-10
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• 2017

Climate change not only has various impacts such as human shoes, economics, the environment, industry, etc. but the damage caused by this is also increasing, it is expected that severe damage will not occur without efforts to respond to climate change ing. Therefore, as the impact of climate change like the extreme weather phenomenon is dailyized and its strength tends to become stronger, as much as the mitigation measures of climate change, as a comparative effort to reduce the negative impact of climate change, adaptation to climate change is necessary. Especially when the damage caused by climate change (intense heat, torrential rain, cold wave and heavy snow etc.) as an institution responsible for the provision of public services such as public institutions, the socio-economic spread to the nation and the people The effect is very large. We confirmed the level of response to climate change for the entire public institution, and selected climate change risk which is relatively important for specific facilities and business establishments of public institutions, climate change adaptation measures We will try to utilize it as basic material of establishment.

• Computers and Concrete
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• v.14 no.1
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• pp.73-90
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• 2014

The traditional destructive tests in damage detection require high cost, long consuming time, repairing of damaged members, etc. In addition to these, powerful equipments with advanced technology have motivated development of global vibration based damage detection methods. These methods base on observation of the changes in the structural dynamic properties and updating finite element models. The existence, location, severity and effect on the structural behavior of the damages can be identified by using these methods. The main idea in these methods is to minimize the differences between analytical and experimental natural frequencies. In this study, an application of damage detection using model updating method was presented on a one storey reinforced concrete (RC) building model. The model was designed to be 1/2 scale of a real building. The measurements on the model were performed by using ten uni-axial seismic accelerometers which were placed to the floor level. The presented damage identification procedure mainly consists of five steps: initial finite element modeling, testing of the undamaged model, finite element model calibration, testing of the damaged model, and damage detection with model updating. The elasticity modulus was selected as variable parameter for model calibration, while the inertia moment of section was selected for model updating. The first three modes were taken into consideration. The possible damaged members were estimated by considering the change ratio in the inertia moment. It was concluded that the finite element model calibration was required for structures to later evaluations such as damage, fatigue, etc. The presented model updating based procedure was very effective and useful for RC structures in the damage identification.