• Journal of the Korean Society for Railway
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• v.19 no.4
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• pp.480-488
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• 2016

For the development of areas around railway lines, subsurface construction using the non-open cut method under the railway has recently been increased. However, when a structure under a railway is constructed, the stress release of the ground is not considered an important factor in the design. In this study, laboratory tests were conducted to determine a zone of stress relaxation. Field tests using an inclinometer were performed to measure the horizontal displacement of the ground during non-open cut construction. The stress release zone and the subgrade stiffness were investigated by numerical analysis. The results of the laboratory tests indicated that the failure zone in the ground was similar to a Rankine's active earth pressure zone. The measured data from the inclinometer in the field tests showed that displacements started when a steel pipe was pushed into the ground. The results of numerical analysis show that lateral earth pressure was also close to Rankine's active earth pressure. The roadbed support stiffness of the soil around the structure decreased to 40% of the original value. The ground around the subsurface structure constructed using nonopen cut methods should be reinforced to maintain the running stability of train.

• The Journal of Korean Medicine
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• v.26 no.3 s.63
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• pp.162-175
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• 2005

Backgrounds : Two stress pathways, the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system, regulate immune system responses through release of corticosteroids, norepinephrine and epinephrine. respectively. These neuromediators act on immune cells via specific receptors on their surface to modulate the production of key regulatory cytokines. Objectives : To evaluate the preventive effects of oriental medicine Hyeolbuchukyeo-tang (HC) on stress. Methods : Mice were divided into three groups: nounal group, control group under immobilization stress and HC group which received Hyeolbuchukyeo-tang (HC) under immobilization stress. following sacrifice, their splenocytes were isolated and splenocyte surface markers were determined. The brains were removed and mRNA determined. In vivo, we separated RNA Iron cultured macrophages (RAW264.7). Results : In our study, immune functions were decreased in stress due mainly to changes of various neuromediators, cytokines and macrophage activities, and the treatment of HC increased those expressions. Conclusions : In summary, the present study documents the anti-stress effects of HC through stress-immune regulation.

• The Korean Journal of Community Living Science
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• v.28 no.2
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• pp.289-300
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• 2017

This study was performed to investigate the effects of academic stress and academic burnout on smartphone addiction in junior high school students. A survey was conducted using a convenient sample drawn from 306 students at six junior high schools in Seoul. Data were analyzed using the SPSS 23.0 program. The results show that 21.6% of students were at risk of smartphone addiction. The high risk of smartphone addiction group used smartphone longer during weekdays and weekends. In addition, the high level of academic stress and academic burnout groups showed higher smartphone addiction scores compared to the lower level of academic stress and academic burnout groups. Smartphone addiction was positively correlated with academic stress and academic burnout. Furthermore, the results show that academic achievement and attending class, academic stress and disengagement, and academic burnout affected smartphone addiction. Therefore, to prevent smartphone addiction in adolescents, academic stress should be reduced in adolescents as well as develop educational programs to help students release or control their academic stress.

• Journal of Applied Biological Chemistry
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• v.63 no.3
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• pp.283-290
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• 2020

Oxidative stress is one of the contributors of neurodegenerative disorders including Alzheimer's disease. According to previous studies, Aster yomena (Kitam.) Honda (AY) possesses variable pharmacological activities including anti-coagulant and anti-obesity effect. In this study, we aimed to determine the neuroprotective effect of ethyl acetate fraction from Aster yomena (Kitam.) Honda (EFAY) against oxidative stress. Therefore, we carried out 3-(4,5-dimethylthiazol-2-yl)-2,3-diphenyl tetrazolium bromide, lactate dehydrogenase (LDH), and 2',7'-dichlorofluorescin diacetate assays in SH-SY5Y neuronal cells treated with hydrogen peroxide (H₂O₂). H₂O₂-treated control cells exhibited reduced viability of cells, and increased LDH release and reactive oxygen species (ROS) production compared to normal cells. However, treatment with EFAY restored the cell viability and inhibited LDH release and ROS production. To investigate the underlying mechanisms by which EFAY attenuated neuronal oxidative damage, we measured protein expressions using Western blot analysis. Consequently, it was observed that EFAY down-regulated cyclooxygenase-2 and interleukin-1β protein expressions in H₂O₂-treated SH-SY5Y cells that mediated inflammatory reaction. In addition, apoptosis-related proteins including B-cell lymphoma-2-associated X protein/B-cell lymphoma-2 ratio, cleaved caspase-9, and cleaved-poly (ADP-ribose) polymerase protein expressions were suppressed when H₂O₂-treated cells were exposed to EFAY. Our results indicate that EFAY ameliorated H₂O₂-induced neuronal damage by regulating inflammation and apoptosis. Altogether, AY could be potential therapeutic agent for neurodegenerative diseases.

• Composites Research
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• v.29 no.1
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• pp.16-23
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• 2016

In this paper, numerical results of sectional analysis, stress recovery and energy release rate were compared with the results of VABS, 3-D FEM through the blade analysis library. The result of stress recovery analysis for one-dimensional model including the stiffness matrix is compared with stress results of three-dimensional FEM. We discuss the configuration of the blade analysis library and compare verifications of numerical analysis results of VABS. Blade analysis library through dimensional reduction and stress recovery is intended to be utilized in conjunction with pre- and post-processing of the analysis program of the composite blade, high-altitude uav's wing, wind blades and tilt rotor blade.

• Journal of Technologic Dentistry
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• v.40 no.4
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• pp.249-259
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• 2018

Purpose: This study aimed to investigate the relationship between dental technology students' life stress and smartphone addiction in order to detect smartphone over-users early, prevent them from getting addicted, and obtain basic data for creating a positive environment for academic achievement by using smartphone in a right way. Methods: The subjects of this study were university students at D University and G University in Daejeon Metropolitan City and Gangwon-do. A questionnaire survey was conducted to the subjects who understood the purpose of this study and participated in it from March 1 to June 10, 2018, and 243 were finally analyzed except 24 questionnaires without sufficient answers. Results: As a result of multiple regression analysis with variables, which were significant in univariate analysis, as independent variables, there were gender and smartphone dependency as general characteristics affecting the degree of smartphone addiction, and family relations and future problems among stress sub-factors were selected as significant variables. Conclusion : In the case of college students, they choose the smartphone as the easiest way to relieve stress because they lack the time and space to actually release stress. Therefore, club activities or on-campus and extra-curricular activities are recommended, and it needs to seek a way to get rid of stress by solving the cause of stress through counseling.

• Proceedings of the KWS Conference
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• 2002.05a
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• pp.139-142
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• 2002

• International Journal of Ocean System Engineering
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• v.3 no.3
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• pp.131-135
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• 2013

We construct the fundamental fields for 3-D arbitrarily shaped plane cracks in by differentiating with respect to a parameter of the crack. As an application of these fundamental fields, the total elastic energy release rate in combined mode cracking is computed.

• International Journal of Korean Welding Society
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• v.5 no.1
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• pp.29-34
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• 2005

Finite element analysis (FEA) and experimental studies on an elastic bending method have been performed in order to control the angular distortion at the fillet weldment for curved panel. Process parameters for the elastic bending method such as clamping span and release time were analyzed with reference to welding condition and geometric effect of the curved panel, which can minimize or prevent the angular distortion by producing a proper skin stress to the fillet weldment. The amounts of the angular distortion decrease almost in a linear manner with an increase in the skin stress. The skin stress required for non-angular distortion at the fillet weldment is strongly dependent on the plate thickness, not the heat intensity applied. The clamping span for obtaining uniform skin stress was defined as functions of the plate thickness and length of the free edge. Clamp should be removed after the fillet weldment is cooled down to room temperature for non-angular distortion. Effectiveness of the elastic bending method established was verified by its application to an actual curved panel.

• Nutritional Sciences
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• v.5 no.4
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• pp.228-233
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• 2002

The low molecular weight zinc-binding protein metallothionein(MT) contains 32% cysteine and has been shown to efficiently scavenge hydroxyl radicals in vitro. MT expression is induced by oxidative stress and an antioxidant role for this protein has therefore been proposed. This review mainly focuses on the evidence for this role arising from studies using genetically modified animals and cells which either over- or under-express MT. Despite some considerable disparity of results in the literature, reported studies do generally support an antioxidant role. Nevertheless, oxidant stress at non-physiological treatment levels has been the preferred experimental model and there is little information about the role of MT in physiological oxidative stress. Although it is presumed that the mechanism by which MT has an antioxidant effect involves oxidation of cysteinal thiols, it is possible that zinc release from MT is in itself an important signalling factor.