• Food Science and Biotechnology
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• 제15권6호
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• pp.833-837
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• 2006

To determine whether alcohol-treated rat liver cells can be protected by a static magnetic field (SMF), we analyzed the blood chemistry and histology of hepatic tissue removed from alcohol-exposed rats that had been exposed to a static magnetic field. The rats were exposed to a 0.3 tesla (3,000 gauss) magnetic field (MF) for 24 hr daily for 5 weeks with appropriate controls. Glutamic pyruvic transaminase activity and the triglyceride levels in animals exposed to the north (N) or south (S) pole of the MF decreased significantly (p<0.01 and p<0.05, respectively) compared with negative control animals with alcohol exposure. A histological examination of hepatic tissue revealed a moderate to severe accumulation of fat vacuoles of various sizes in the cytoplasm of the hepatocytes of animals in the negative control group throughout the study; whereas in groups exposed to the MF poles, fewer fat vacuoles were seen compared with the negative control group. Electron microscopic observations showed that exposure to the N or S pole protected organelles, including the nucleus, from damage during exposure to this toxic agent, as indicated by the fact that the nucleus and the mithochondria virtually retained their shape throughout this study. These results suggest that exposure to a SMF could be an excellent way of protecting against alcohol-induced damage to the rat liver cell.

• Steel and Composite Structures
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• 제25권4호
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• pp.403-413
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• 2017

The fabric braided braking hose that delivers the driver's braking force to brake cylinder undergoes the large deformation cyclic motion according to the steering and bump/rebound motions of vehicle. The cyclic large deformation of braking hose may give rise to two critical problems: the interference with other adjacent vehicle parts and the micro cracking stemming from the fatigue damage accumulation. Hence, both the hose deformation and the fatigue damage become the critical issue in the design of braking hose. In this context, this paper introduces a multi-objective optimization method for minimizing the both quantities. The total length of hose and the helix angles of fabric braided composite layers are chosen for the design variables, and the maximum hose deformation and the critical fatigue life cycle are defined by the individual single objective functions. The trade-off between two single objective functions is made by introducing the weighting factors. The proposed optimization method is validated and the improvement of initial hose design is examined through the benchmark simulation. Furthermore, the dependence of optimum solutions on the weighting factors is also investigated.

• Korean Journal of Pharmacognosy
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• 제45권2호
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• pp.161-167
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• 2014

Ganoderma lucidum L. (GL) is a traditional oriental medicine that has been widely used as anti-inflammatory, antitumor and anti-oxidant in Korea and other Asian countries. In this study, we investigated the ethanol extract of GL has neuroprotective effects in murine hippocampal HT22 cells. GL ethanol extract has the potent neuroprotective effects on glutamate-intoxicated cells by inducing the expression of heme oxygenase (HO)-1 in HT22 cells. GL ethanol extract increased JNK phosphorylation. Obviously, When we treated the GL extract with c-Jun N-terminal kinase (JNK) inhibitor (SP600125), HO-1 expression was reduced. Moreover, we found that GL treatment caused the nuclear accumulation of Nrf2. In conclusion, the ethanol extract of GL significantly protects glutamate-induced oxidative damage by induction of HO-1 via Nrf2, JNK pathway in mouse hippocampal HT22. These results suggest that GL ethanol extract would be a good source for taking active compounds and may be a potential pharmaceutical products for brain disorder induced by neuronal damage and oxidative stress.

• Structural Engineering and Mechanics
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• 제61권4호
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• pp.483-496
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• 2017

Earthquake excitations may induce important amount of seismic energy into structures. Current design philosophy mainly deals with the plastic deformations of replaceable energy dissipating devices rather than damages accumulated on structural members. Since earthquake damage is substantially concentrated on these devices they could be replaced after severe earthquakes. In this study, the efficiency of steel cushion (SC) on seismic improvement of a vulnerable reinforced concrete (RC) frame is determined by means of several numerical simulations. The cyclic shear behaviors of SCs were determined by performing quasi-static tests. The test results were the main basis of the theoretical model of SCs which were used in the numerical analysis. These analyses were performed on three types of RC frames namely bare frame (BF), full-braced frame (F-BF) and semi-braced frame (S-BF). According to analysis results; implementation of SCs has considerable effects in reducing the storey shear forces and storey drifts. Moreover plastic energy demands of structural elements were reduced which indicates a significant improvement in seismic behavior of the RC frame preventing damage accumulation on structural elements. Full-braced frame having SCs with the thickness of 25 mm has better performance than semi-braced frame interms of energy dissipation. However, global energy dissipation demand of S-BF and F-BF having SCs with the thickness of 18 mm are almost similar.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제32권10호
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• pp.817-822
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• 2008

Fretting wear is one of the important degradation mechanisms of steam generator tubes in the nuclear power plants. Especially, impact fretting wear occurred between steam generator tubes and tube support plates or anti-vibration bar. Various tests have been carried out to investigate the wear mechanisms and to report the wear coefficients. Those are fruitful to get insight for the wear damage of steam generator tubes; however, most wear researches have concentrated on sliding wear of the steam generator tubes, which may not represent the wear loading modes in real plants. In the present work, impact fretting tests of steam generator tube were carried out. A wear progress model for impact-fretting wear has been investigated and proposed. The proposed wear progress model of impact-fretting wear is as follows; oxide film breaking step at the initial stage, and layer formation step, energy accumulation step and finally particle torn out step which is followed by layer formation in the stable impact-fretting progress. The wear coefficient according to the work-rate model has been also compared with one between tube and support.

• Journal of the Korean Society for Heat Treatment
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• 제7권3호
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• pp.155-159
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• 1994

As Cr-Mo-V steels have excellent mechanical and creep properties at elevated temperatures, they are extensively used in power plants. However, the steam turbine components are supposed to have suffered material degradation during long-term service at elevated tenperatures. Many efforts have been made to assess the safety and residual life of these components by means of non-destructive methods such as plastic replication, hardness and electric resistance techniques. Recently, a parameter correlating hardness changes during long-term heating to those during creep was introduced and it was named 'G parameter'. The electric resistivity as well as hardness are affected by damage accumulation, but there have been no efforts to correlate G parameter to resistivity changes. In this study, relationship between G parameter and changes in electric resistivity was investigated using artificially aged Cr-Mo-V steel. It is well understood that G parameter can be applied to electric: resistance techmique.

• Herbal Formula Science
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• 제28권2호
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• pp.179-187
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• 2020

Objectives : This study investigated the hepatoprotective effects effects of Jageum-jung extract on alcohol-induced liver disease mice model. Methods : Alcoholic liver disease was induced by Ethanol in C57/BL6 male mice, which were fed Lieber-DeCarli liquid diet containing ethanol. Jageum-jung (100,200 and 300 mg/kg bw/day) were orally administered daily in the alcoholic fatty liver disease mice for 16 days. Results : The results indicate that Jageum-jung promotes hepatoprotective effects by significantly reducing aspartate transaminase (AST) and alanine transaminase (ALT) levels as indicators of liver damage in the serum. Furthermore, Jageum-jung decreased accumulation of triglyceride and total cholesterol, increased levels of superoxide dismutase (SOD) and glutathione (GSH) in the serum of the alcoholic fatty liver disease mice model. Additionally, it improved the serum alcohol dehydrogenase (ADH) activity. Conclusions : This study confirmed the anti-oxidative and hangover elimination effects of Jageum-jung extract, and suggests the possibility of using Jageum-jung to treat alcholic liver disease.

• Steel and Composite Structures
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• 제17권5호
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• pp.573-599
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• 2014

A new type of connection for steel-concrete composite bridges was developed by the Steel Structures Laboratory of Ecole Poytechinque $F{\acute{e}}d{\acute{e}}rale$ de Lausanne. Resistance to longitudinal shear is based on the development of shear stresses in the confined interfaces which form the connection. Confinement is provided by the reinforced concrete slab which encloses the connection and restrains the uplift (lateral separation) of the interfaces by developing normal stresses. The experimental investigation of the interfaces, under static and cyclic loading, enabled the development of the laws describing the structural behaviour of each interface. Those laws were presented by the authors in previous papers. The current paper focuses on the continuity of the research. It presents the experimental investigation on the new connection by means of push-out tests on specimens submitted to static and cyclic shear loading. Investigation revealed that the damage in the connection, due to cyclic loading, is expressed by the accumulation of a residual slip. A safe fatigue failure criterion is proposed for the connection which enabled the verification of the connection for the fatigue limit state with respect to the limit of fatigue. A numerical model is developed which takes into account the laws describing the interface behaviour and the analytical expressions for the confinement effect, the latter obtained by performing finite element analysis. This numerical model predicts the shear resistance of the connection and enables to assess its fatigue limit which is necessary for the fatigue design proposed.

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2989-2998
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• 2022

Line contact structures, such as the contact between graphite brick and graphite tenon, widely exist in high-temperature gas-cooled reactors. Due to the stress concentration effect, the line contact area is one of the dangerous positions prone to failure in the nuclear reactor core. In this paper, the failure mechanism of line contact structures composed of IG11 nuclear graphite column and brick were investigated by means of experiment and finite element simulation. It was found that the failure process mainly includes three stages: firstly, the damage accumulation in nuclear graphite material led to the characteristic yielding of the line contact structure, but no macroscopic failure can be observed at this stage; secondly, the stresses near the contact area met Mohr failure criterion, and a crack initiated and propagated laterally in the contact zone, that is, local macroscopic failure occurred at this stage; finally, a second crack initiated in the contact area and developed in to a Y-shape, resulting in the final failure of the structure. This study lays a foundation for the structural design and safety assessment of high-temperature gas-cooled reactors.

• Journal of Korean Medical classics
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• 제36권3호
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• pp.27-54
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• 2023

Objectives : To determine the background against which Zhishi has been applied to treat Pi pattern, through examination of changes in Pi pattern treatments in a historical context. Methods : The properties and nature of Zhishi as written in multiple bencao texts were analyzed. In addition, understanding of the Pi pattern, the changes in its treatment were examined diachronically based on opinions of Zhang Zhongjing, Zhugong, and Li Dongyuan. Examples of Zhishi application in Pi pattern treating formulas were collected and their mechanisms analyzed. Results : Zhishi is strongly effective in relieving accumulation and stagnation, due to its properties of dispersing and lowering. The early view of contrasting Pi with Jiexiong shifted to viewing the Pi pattern as an inner damage, from the perspective of rising and lowering of the Qi mechanism based on the Spleen and Stomach. As a result, Zhishi became a key ingredient in the treatment of the Pi pattern. Conclusions : As the perspective of seeing Pi as one end of the Yin-Yang coupling with Jiexiong from the Shanghanlun shifted to seeing it as a problem of Qi mechanism of the Spleen and Stomach, Zhishi became a key ingredient in the formulas to treat Pi pattern. The complexity of Zhishi's direction made it appropriate to treat the changed Pi pattern.