• Journal of the Korean housing association
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• v.7 no.2
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• pp.9-17
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• 1996

The Purpose of this study is to understand the relationship between residential environment and healthy behavior by examining the effect of environmental stress on psychology and physiology. With anxiety, the acute environmental stressor activates sympathy nerve system and the chonic environmental stressor activates the intenal secretion system because this stress induces depression. Thus, we could find that the continuity of these kinds of stresses brings the chronic disease.

• Korean Journal of Materials Research
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• v.7 no.8
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• pp.650-653
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• 1997

In large generators in power plants, stator winding insulations is exposed to a combination of thermal, electrical, mechanical, environmental stresses in service. These combined stresses cause insulation aging which leads to final insulation breakdown. In order to identify the breakdown mechanism, the stator winding insulation materials which are composed of mica-epoxy is analyzed by the component of materials with EDS, SEM techniques. We concluded that the potassium ions of mica are replaced by hydrogen ions at boundary area of mica-epoxy and/or mica-mica. It is proposed that through these phenomena, the conductive layers of potassium ions enable high voltage fields of multiple stresses to create voids and microcracks.

• Structural Engineering and Mechanics
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• v.61 no.3
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• pp.389-396
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• 2017

Concrete pavements are subjected to traffic and environmental loadings. Repetitive type of such loading cause fatigue distress which leads to failure by forming cracks in pavement. Fatigue life of concrete pavement is calculated from the stress ratio (i.e. the ratio of applied flexural stress to the flexural strength of concrete). For the correct estimation of fatigue life, it is necessary to determine the maximum flexural tensile stress developed for practical loading conditions. Portland cement association PCA (1984) and Indian road congress IRC 58 (2015) has given charts and tables to determine maximum edge stresses for particular loading and subgrade conditions. It is difficult to determine maximum stresses for intermediate loading and subgrade conditions. The main purpose of this study is to simplify the analysis of rigid pavement without compromising the accuracy. Equations proposed for determination of maximum flexural tensile stress of pavement are verified by finite element analysis.

• Structural Engineering and Mechanics
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• v.5 no.6
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• pp.755-765
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• 1997

Within the framework of anisotropic combined viscoplastic hardening formulation, accounting macroscopically for residual stress as well as texture development at finite deformations of metals, simple shear analyses for the simulation of fixed-end torsion experiments for ${\alpha}$-Fe, Al and Cu at different strain rates are reviewed with an emphasis on the role of constitutive spins. Complicated responses of the axial stresses with monotonically increasing shear deformations can be successfully described by the capacity of orthotropic hardening part, featuring tensile axial stresses either smooth or oscillatory. Temperature effect on the responses of axial stresses for Cu is investigated in relation to the distortion and orientation of yield surface. The flexibility of this combined hardening model in the simulation of finite inelastic strains is discussed with reference to the variations of constitutive spins depending upon strain rates and temperatures.

• Structural Engineering and Mechanics
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• v.46 no.1
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• pp.91-110
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• 2013

This paper proposes a novel iterative procedure for the design of planar reinforced concrete structures in which the reinforcement is designed for stresses calculated in a nonlinear finite element analysis. The procedure is intended as an alternative to strut and tie modeling for the design of complex structures like deep beams with openings. Practical reinforcement arrangements are achieved by grouping the reinforcement into user defined horizontal and vertical bands. Two alternative strategies are proposed for designing the reinforcement which are designated A and B. Design constraints are specified in terms of permissible stresses and strains in the reinforcement and strains in the concrete. A case study of a deep beam with an opening is presented to illustrate the method. Comparisons are made between design strategies A and B of which B is shown to be most efficient. The resulting reinforcement weights are also shown to compare favorably with those previously reported in the literature.

• The Korean Journal of Ecology
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• v.17 no.1
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• pp.91-100
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• 1994

Although the types of stress are various, environmental stresses generally increase the amounts of reactive oxygen species in plants. These reactive oxygen species stimulate stress-ethylene synthesis and accelerate senescence of plants. However, when stress-ethylene synthesis is suppressed through antioxidative enzymes and antioxidants, the resistance of plants against stress could be induced by limited production of ethylene.

• The Korean Journal of Food And Nutrition
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• v.10 no.1
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• pp.122-126
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• 1997

Bifidobacteria have been known as beneficial inhabitant of human intestine. Therefore, bifidobacteria began to be noticed as a starter in the manufacture of fermented dairy products. Perhaps the key for effective use of bifidobacteria in commercial dairy products is the maintenance of viability of bifidobacteria during large scale preparation of starter culture and distribution of products. So we tried to obtain the bifidobacteria having suitable characteristics for using as a starter in the manufacture of fermented dairy products. Among bifidobacteria isolated from Korean, E-4 strain showed the highest resistance to oxygen. To know whether the selected strain will be fit for manufacture of fermented dairy products, we also investigated resistance of the selected strain to HCI. The selected strain, E-4, was more resistant to environmental stresses such as oxygen, H2O2 and HCI than Bifidobacterium longum known as resistant strain to environmental stresses. According to carbohydrate fermentation patterns and morphological characteristics, E-4 strain was identified as B. bifidum. In conclusion, the selected strain, E-4, was thought to be fit for manufacture of fermented dairy products.

• Environmental Engineering Research
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• v.10 no.1
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• pp.15-21
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• 2005

A computer program is developed for the prediction of the flow pattern and the removal efficiency of suspended solid (SS) in a circular secondary clarifier. In this study the increased density effect by SS on hydrodynamics has been systematically investigated in terms of Froude Number (Fr), baffle existence, and a couple of important empirical models associated with the particle settling and Reynolds stresses. A control-volume based-finite difference method by Patankar is employed together with the SIMPLEC algorithm for the resolution of pressure-velocity coupling. The k-ε turbulence and its modified version are incorporated for the evaluation of Reynolds stresses. The calculation results predicts well the overall flow pattern such as the waterfall phenomenon at the front end of the clarifier and the bottom density current with the formation of strong recirculation especially for the case of decrease of Fr. Even if there are some noticeable differences in the prediction of two turbulence models, the calculated results of the radial velocity profiles are generally in good agreement against experimental data appeared in open literature. Parametric investigation has been systematically made with the Fr and baffle condition with detailed analysis.

• Toxicological Research
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• v.11 no.1
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• pp.161-168
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• 1995

It has been found that various stress challenges induce the myocardial antioxidant enzymes and produce an acquisition of the cellular resistance to the ischemic injury in animal hearts. Most of the stresses, however, seem to be guite dangerous to an animal's life. In the present study, therefore, we tried to search for safely applicable stress modalities which could lead to the induction of antioxidant enzymes and the production of myocardial tolerance to the ischemia-reperfusion injury. Male Sprague-Dawley rats (200-250 g) were exposed to various non-fatal stress conditions, i.e., hyperthermia (environmental temperature of $42^{\circ}C$ for 30 min, non-anesthetized animal), iramobilization (60 min), treadmill exercise (20 m/min, 30min), swimming (30 min), and hyperbaric oxyflenation (3 atm, 60 min), once a day for 5 days. The activities of myocardial antioxidant enzymes and the ischemia-reperfusion injury of isolated hearts were evaluated at 24 hr after the last application of the stresses. The activities of antioxidant enzymes, superoxide dismutase (SOD), catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase (G6PD), were assayed in the freshly excised ventricular tissues. The ischemia-reperfusion injury was produced by 20 min-global ischemia followed by 30 min-reperfusion using a Langendorff perfusion system. In swimming and hyperbaric oxygenation groups, the activities of SOD and G6PD increased significantly and in the hyperthermia group, the catalase activity was elevated by 63% compared to the control. The percentile recoveries of cardiac function at 30 min of the post-ischemic reperfusion were 55.4%, 73.4%, and 74.2% in swimming, the hyperbaric oxygenation and the hyperthermia groups, respectively. The values were significantly higher than that of the control (38.6%). In additions, left ventricular end-diastolic pressure and lactate dehydrogenase release were significantly reduced in the stress groups. The results suggest that the antioxidant enzymes in the heart could be induced by the apparently safe in vivo-stresses and this may be involved in the myocardial protection from the ischemia-reperfusion injury.

• Proceedings of the Zoological Society Korea Conference
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• 2003.08a
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• pp.193.4-193
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• 2003

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