• KOREAN JOURNAL OF CROP SCIENCE
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• v.24 no.1
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• pp.57-65
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• 1979

In order to find the physiology of responess In order to find the physiology of responses and mechanisms of the actumlation of free proline at low temperatures and water stress. the temperature range, the effect of prolonged exposure to low temperatures, the light-dependence of proline accumulation in barle was significantly lower than in wheat. Proline accumulation at 5\circ C without water stress was shown to be light-dependent. Proline accumulation by water stress was not light-dependent at 2$0^{\circ}C$ but at 5$^{\circ}C$.

• The Korea Journal of Herbology
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• v.21 no.2
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• pp.63-75
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• 2006

Objectives : We investigated the effects of Liriopis Tuber on the nervous protection. Methods : We measured the reaction behavior with EPM(Elevated Plus Maxe) and MWM(Morris Water Maze) after applying restraint stress to rats. Also, the degrees of AchE generation were measured with immunohistochemical method in the regions of hippocampus, and the degree of TH generation in the regions of VTA and LC, respectively. Results : 1. As the results of measuring how long EPM which reflects anxiety reaction stayed in the open arm, there was the trend which can suppress anxiety reaction in the MMD+stress group(Liriopis Tuber+stress) but no statistical significance. The counting results how many EPM passed between opened and closed arm showed suppression trend against a physical activity in the saline+stress group but there was no statistical significance. 2. According to the result of MWM, the saline+stress group showed the learning retardation which means increased time arriving at goal compared to ti1e normal group at the second and third day of measurement. On the contrary, a learning retardation was significantly decreased in the MMD+stress group. Among the probe trial test a memory loss occurred in the saline+stress group, meanwhile memory ability was notably increased in the saline-stress group. 3. The degree of TH generation was investigated at the VTA and LC respectively after test animals treated with drug. In the saline+stress group, TH-immunoreactive cells were significantly increased, and these stress-induced TH increases were suppressed in the saline+stress group at the VTA region. However, the saline+stress group did not show any significant difference. 4. the degree of AchE generation was investigated at the CA3 of hippocampus. The saline+stress group showed that AchE-immunoreactive cells were significantly decreased. Those stress-induced reductions of AchE cells were meaningfully recovered in the saline+stress group. Although the cells showed recovery trend in the region of CA1 of hippocampus, statistical significance was not observed. Conclusion : The results of our study indicate that Liriopis Tuber can improve spatial memory ability of rats applied a restraint stress. This improvement of the spatial memory ability is considered to have an efficacy of nervous protection that Liriopis Tuber suppresses the generation of AchE in the hippocampus region and enhances the generation of TH in the VTA.

• Journal of Oriental Neuropsychiatry
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• v.2 no.1
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• pp.51-69
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• 1991

This experiment was conducted to study anti-stress effects of Guibiondamtang on several measures of stress, which were number of lever pressing, weight changes, water intake and gastroduodenal ulcer. The following results were observed: 1. There were no significant differences between the control group and the sample group in total number of lever pressing. And no significant differences were observed in the shock duration and the shock length. 2. The median water intake during the stress was 25ml for the sample group and 17ml for the control group and the difference was not statistically significant. 3. The median body weight losess after the psychological stress was given were 28g for the sample group and 35g for the control group and the difference was not statistically significant. 4. The mean frequencies of gastric ulcers induced by the psychological stress were 0.3 for the sample group and 2.3 for the control group and the difference was statistically significant. 5. The mean lengths of gastric ulcers induced by the psychological stress were 0.3mm for the sample group and 2.8mm for the control group and the difference was statistically significant. 6. The mean ratings of gastric ulcers induced by the psychological stress were 0.7 for the sample group and 1.9 for the control group and the difference was stastically significant. Thus it may be concluded that Guibiondamtang has an antistress effect.

• The Korean Journal of Physiology and Pharmacology
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• v.13 no.4
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• pp.315-319
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• 2009

Astragalus Membranaceus (AM) is a useful Korean herb that has been clinically prescribed for stress-related illness. The objective of the present study was to examine the anti-stress effects of AM on repeated stress-induced alterations of anxiety, learning and memory in rats. Restraint stress was administered for 14 days (2h/day) and AM (400mg/kg) given by oral administration, in the AM group, for the same period. Starting on the eighth day, the rats were tested for spatial memory on the Morris water maze test (MW) and for anxiety on the elevated plus maze (EPM). Changes of expression on immunohistochemistry were studied for cholineacetyl transferase (ChAT) and tyrosine hydroxylase (TH) in the brain. The results showed that the rats treated with AM had significantly reduced stress-induced deficits on learning and memory on the spatial memory tasks. In addition, the ChAT immunoreactivities were increased. In the EPM, treatment with AM increased the time spent in the open arms (p<0.001) compared to the control group. In addition, AM treatment also normalized increases of TH expression in the LC (p<0.001). In conclusion, administration of AM improved spatial learning and memory and reduced stress-induced anxiety. Thus, the present results suggest that AM is able to recover behavioral and neurochemical impairments induced by stress.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1159-1168
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• 2013

In pressurized water nuclear reactors (PWRs), the reactor pressure vessel (RPV) upper head contains penetration nozzles that use a control rod drive mechanism (CRDM). The penetration nozzle uses J-groove weld geometry. Recently, the occurrence of cracking in alloy 600 CRDM penetration nozzle has increased. This is attributable to primary water stress corrosion cracking (PWSCC). PWSCC is known to be susceptible to the welding residual stress and operational stress. Generally, the tensile residual stress is the main factor contributing to crack growth. Therefore, this study investigates the effect on weld residual stress through different analysis methods for normal operating conditions using finite element analysis. In addition, this study also considers the effect of repeated normal operating condition cycles on the weld residual stress. Based on the analysis result, this paper presents a normal operating condition analysis method.

• Herbal Formula Science
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• v.10 no.2
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• pp.97-112
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• 2002

In order to investigate the effect of Sagoonja-Tang, Samool-Tang and Yookmijihwang-Tang against the cold, heat and immobilization stress, each formula was injected intragastically to mice exposed to forced cold water swimming($4^{\circ}C$), forced hot water swimming($42^{\circ}C$) and immobilization stress before measuring the change of plasma corticosterone level of mice. The results were as follows: 1. One hour after each Sagoonja-Tang, Samool-Tang, Yookmijihwang-Tang with the dose of 1g／kg, 3g／kg each were administered to mice, we put cold stress($4^{\circ}C$) on mice for 3min. Then those prescriptions didn't show any significant effect on plasma corticosterone level. however, Yookmijihwang-Tang(1g/kg) showed a significant increase(p〈0.05), and Samool-Tang(3g/kg) showed a small increase. 2. One hour after Samool-Tang, Sagoonja-Tang and Yookmijihwang-Tang with the dose of 1g／kg, 3g／kg each were administerd, mice exposed to heat stress($42^{\circ}C$) for 3 min. Samool-Tang(1g/kg) and Yookmijihwang-Tang(lg/kg) showed significant decrease of corticosterone level(p〈0.01, p〈0.05) but Sagoonja-Tang didn't change it. In the case of the dose of 3g/kg, only Samool-Tang decreased corticosterone level(P〈0.01), but Sagoonja-Tang, Yookmijihwang-Tang didn't make significant effect on plasma corticosterone level of the mice exposed to heat stress($42^{\circ}C$ ). 3. Those mice which exposed to immobilization stress one hour after Sagoonja-Tang, Samool-Tang, Yookmijihwang-Tang with the dose of 1g/kg and 3g/kg didn't show effective decrease of corticosterone level. However, Sagoonja-Tang(3g/kg), Samool-Tang(lg/kg, 3g/kg) showed the effect of mild increase of corticosterone level rather than decrease. These data revealed that the effect-variation of prescriptions depended on the kinds of stress and the dose of prescriptions had a different effect on therapy.

• Geomechanics and Engineering
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• v.21 no.3
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• pp.247-258
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• 2020

The shear strength of unsaturated soils, a research hotspot in geotechnical engineering, has great guiding significance for geotechnical engineering design. Although kinds of calculation models for the shear strength of unsaturated soil have been put forward by predecessors, there is still need for new models to extensively consider the nonlinear variation of shear strength, particularly for the nonlinear effect of the net normal stress on the shear strength of unsaturated soil. Here, the shear strength of unsaturated soils is explored to study the nonlinear effects of net normal stress with the introduction of a general nonlinear Mohr-Coulomb (M-C) strength criterion, and the relationship between the matric suction (or suction stress) and degree of saturation (DOS) constructed by the soil-water characteristics curve (SWCC) of van Genuchten is also applied for unsaturated soil. Then, two calculation models (i.e., an envelope shell model and an effective stress model) are established for the shear strength of unsaturated soils under the nonlinear strength theory. In these two models, the curve of the shear strength of unsaturated soils versus the net normal stress exhibits a tendency to gently. Moreover, the proposed formulas have flexibility and convenience with five parameters (for the effective stress model) or six parameters (for the envelope shell model), which are from the M-C strength parameters of the saturated soil and fitting parameters of SWCC of van Genuchten. Thereafter, by comparison with the classical theory of the shear strength of unsaturated soils from some actual cases, the rationality and accuracy of the present models were verified.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.15 no.1
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• pp.28-32
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• 2019

In nuclear power plant operation and spent fuel canisters, it is necessary to provide a sound technical basis for the safety and security of long-term operation and storage respectively. Recently, the peening technology is being discussed and the technology will be adopted to ASME Section III, Division 1, Subsection NX (2019 Edition). The peening is prohibited in current edition, but it will be approved in 2019 Edition and adopted. However, Surface stress improvement techniques such as the peening is used to mitigate SCC susceptible in operating nuclear plants. Although the peening will be approved to ASME CODE, there are no performance criteria listed in the 2019 edition. The Korean International Working Group (KIWG) formed a new Task Group named "Advanced Surface Stress Improved Technology". The task group will develop a CODE CASE to address PWSCC(Primary Water Stress Corrosion Cracking) and CISCC(Chloride Induced Stress Corrosion Cracking) for new ASME Section III components. TG-ASSIT was started to make peening performance criteria for ASME Section III (new fabrication) applications. The objective of TG-ASSIT is to gain consensus among the relevant Code groups that requirements/mitigation have been met.

• Journal of Life Science
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• v.27 no.7
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• pp.826-833
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• 2017

The rising concentration of atmospheric carbon dioxide is causing ocean acidification and global warming. The seahorse is an important species in marine ecosystems and fishery markets, however, their populations have recently decreased due to ocean acidification. As a result, we examined changes in the physiological responses of the spotted seahorse Hippocampus kuda when it was exposed to acidic sea water (pH 6.0, 6.5, and 7.0) and normal seawater (pH 8.0 as the control) over a period of 15 days. As the pH decreased, the seahorses' body weight and length also decreased. Components in body of ash, the crude lipids and crude proteins also differed significantly with changes in pH, due to stress caused by the seahorses' exposure to the acidic water conditions. The superoxide dismutase levels were significantly lower in the pH 6.0 and 6.5 groups than they were in the pH 7.0 and pH 8.0 groups. However, the catalase and glutathione levels were significantly higher in the acidic sea water groups. We suggest that decreasing the pH level of rearing water induces a stress response in H. kuda, damaging their ability to maintain their homeostasis and energy metabolism. Antioxidant enzymes are generally sensitive to acidic stress; in this study, the antioxidant activity was significantly affected by the pH level of the rearing water. These results indicate that physiological stress, induced by exposure to acidification, induces an antioxidant reaction, which can reduce general components in the body and the growth of H. kuda.

• Journal of Environmental Science International
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• v.22 no.6
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• pp.705-715
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• 2013

The response of the freshwater microalga Chlorella vulgaris to mercuric ion ($Hg^{2+}$) stress was examined using chlorophyll a fluorescence image analysis and O-J-I-P analysis as a way to monitor the toxic effects of mercury on water ecosystems. The levels of photosynthetic pigments, such as chlorophyll a and b and carotenoids, decreased with increasing $Hg^{2+}$ concentration. The maximum photochemical efficiency of photosystem II(Fv/Fm) changed remarkably with increasing $Hg^{2+}$ concentration and treatment time. In particular, above $200{\mu}M\;Hg^{2+}$, considerable mercury toxicity was seen within 2 h. The chlorophyll a fluorescence transient O-J-I-P was also remarkably affected by $Hg^{2+}$; the fluorescence emission decreased considerably in steps J, I, and P with an increase in $Hg^{2+}$ concentration when treated for 4 h. Subsequently, the JIP-test parameters (Fm, Fv/Fo, RC/CS, TRo/CS, ETo/CS, ${\Phi}_{PO}$, ${\Psi}_O$ and ${\Phi}_{EO}$) decreased with increasing $Hg^{2+}$ concentration, while N, Sm, ABS/RC, DIo/RC and DIo/CS increased. Therefore, a useful biomarker for investigating mercury stress in water ecosystems, and the parameters Fm, ${\Phi}_{PO}$, ${\Psi}_O$, and RC/CS can be used to monitor the environmental stress in water ecosystems quantitatively.