• Korean Journal of Animal Reproduction
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• v.21 no.4
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• pp.325-333
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• 1997

Recent evidence indicates that growth factors modulate response of mammary epithelial cells to environmental stress. The objective of this study was to examine the cellular and biochemical responses of mammary tissue to environmental stress caused by artificial mastitis. For experimental a, pp.oach, toxins of most mastitis causing organisms(Staph. aureus or Strep. agalactiae) and heat stress(42$^{\circ}C$) were artificially exposed to mammary tissue. Effects of these environmental stresses on cell growth, cell death and heat shock protein synthesis were examined. Lactating mammary tissure were cultured under basal medium(DMEM) su, pp.emented with insulin(10$\mu\textrm{g}$/ml) and aldosterone(1$\mu\textrm{g}$/ml). All treatment groups in heat stress at 42$^{\circ}C$ incubation significantly decreased DNA synthesis rates in comparison with those at 39$^{\circ}C$(P<0.05), however, these decreased DNAa synthesis rates were recovered by addition of adenosine(10$\mu$M) and IGFI(10ng/ml). Similar results were obtained when tissue growth rates were measured by DNA content/tissue. Strep. agalactiae toxin did not significantly decreased DNA content/tissue in comparison with no treatment of bacterial toxin with or without heat stress, however, tended to decrease DNA contents/tissue without heat stress. In the fluorography analysis, heat stress(42$^{\circ}C$ incubation) slightly increased 35S-methoionine labelled 70kd protein synthesis. These results indicate that environmental stress caused by artificial mastitis slightly decreased mammary growth or mammary size, however, these results could be recovered by addition of adenosine and IGF-I.

• Environmental Analysis Health and Toxicology
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• v.3 no.3_4
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• pp.9-15
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• 1988

The word of stress crime from Latin language as stringere and it was used in medical fields from 1935. According to Selye, all the biological bodies reveal physilolgical changes when some stimulation exceed normal levels, and consequently the pituitary gland and adrenal systems are activated. Jacob expressed that stress is the loss of homeostasis by physical, chemical, and emotional stimulation. When biological organisms receive extreme stress the amount of catecholamine excretion are increase. Author investigated the catecholamine contents in rat urine after giving the low temperature stress, noise stress, and water immersion stress. The 24 hours rat urine was collected by adding 1 ml 6 N-HCl and the sample is passed through Bio-Rex 70 samples treatment column to extract catecholamine and detected the catecholamine with HPLC-fluorescence detetor. The highest epinephrine concentration was 67.14 ng in water immersion stress condition and the dopamine concentration of 221.37 ng was shown in the low temperature stress condition.

• Proceedings of the Korean Society of Plant Biotechnology Conference
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• 2005.11a
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• pp.166-166
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• 2005

• Transactions of Materials Processing
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• v.20 no.2
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• pp.173-178
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• 2011

Environmental Stress Cracking(ESC) is one of the most common causes of unexpected brittle failure of thermoplastic polymers. The exposure of polymers to liquid chemicals tends to accelerate the crazing process, initiating crazes at stresses that are much lower than the stress causing crazing in air. In this study, ESC of acrylonitirile butadiene styrene(ABS) was investigated as a function of the molding conditions such as injection velocity, packing pressure, and melt temperature. A constant strain was applied to the injection molded specimens through a 1.26% strain jig and a mixture of toluene and isopropyl alcohol was used as the liquid chemical. In order to examine the effects of the molding conditions on ESC, an experimental design method was adopted and it was found that the injection velocity was the dominant factor. In addition, predictions from numerical analyses were compared with the experimental results. It was found that the residual stress in the injection molded part was associated with the environmental stress cracking resistance (ESCR).

• Mycobiology
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• v.47 no.3
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• pp.346-349
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• 2019

AMP-activated protein kinase sucrose non-fermenting 1 (Snf1) is a representative regulator of energy status that maintains cellular energy homeostasis. In addition, Snf1 is involved in the mediation of environmental stress such as salt stress. Snf1 regulates metabolic enzymes such as acetyl-CoA carboxylase, indicating a possible role for Snf1 in metabolic regulation. In this article, we performed nuclear magnetic resonance (NMR) spectroscopy to profile the metabolic changes induced by Snf1 under environmental stress. According to our NMR data, we suggest that Snf1 plays a role in regulating cellular concentrations of a variety of metabolites during environmental stress responses.

• Computers and Concrete
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• v.17 no.2
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• pp.173-188
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• 2016

Generally, thermal stress induced by hydration heat causes cracking in mass concrete structures, requiring a thorough control during the construction. The prediction of the thermal stress is currently undertaken by means of numerical analysis despite its lack of reliability due to the properties of concrete varying over time. In this paper, a method for the prediction of thermal stress in concrete structures by adjusting thermal stress measured by a thermal stress device according to the degree of restraint is proposed to improve the prediction accuracy. The ratio of stress in concrete structures to stress under complete restraint is used as the degree of restraint. To consider the history of the degree of restraint, incremental stress is predicted by comparing the degree of restraint and the incremental stress obtained by the thermal stress device. Furthermore, the thermal stresses of wall and foundation predicted by the proposed method are compared to those obtained by numerical analysis. The thermal stresses obtained by the proposed method are similar to those obtained by the analysis for structures with internally as well as externally strong restraint. It is therefore concluded that the prediction of thermal stress for concrete structures with various boundary conditions using the proposed method is suggested to be accurate.

• Proceedings of the Korean Environmental Health Society Conference
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• 2004.06a
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• pp.178-181
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• 2004

Di-n-butyl phthalate (DBP) is used extensively in the plastic industry and has been known as an environmental hormone (endocrine disruptor). Present study was undertaken to examine whether DBP can induce oxidative stress in mice. In this study, oxidative stress was measured in terms of the modification of lipid peroxidation and gamma-glutamyltranspeptidase (${\gamma}-GT$) activity. The activity of ${\gamma}-GT$, the level of lipid peroxidation and serum toxicity index were measured in male ICR mice after treatment with DBP (5 g/kg, po). Administration of DBP was found to significantly increase the level of lipid peroxidation approximately 2 fold in liver. The activity of ${\gamma}-GT$ in the liver of DBP-exposed animals was also increased approximately 2.5 fold. However, DBP did not alter the parameters for hepatotoxicity and nephrotoxicity such as alanine aminotransferase (ALT), aspartate aminotransferase (AST) and creatinine. These results indicate that DBP can induce oxidative stress in mice. The ${\gamma}-GT$ activity is considered to be increased as one of the adaptive defense mechanisms to oxidative stress induced by DBP.

• Journal of Environmental Science International
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• v.26 no.12
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• pp.1399-1405
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• 2017

We compared the spatial distribution of several heat stress indices (the Wet-Bulb Globe Temperature(WBGT) index, Environmental Stress Index (ESI), and Modified Discomfort Index(MDI)) for the heat wave of June 6~August 26, 2016, in Daegu. We calculated the heat stress indices using data from the high density urban climate observation network in Daegu. The observation system was established in February. 2013. We used data from a total of 38 air temperature observation points (23 thermometers and 18 automatic weather stations). The values of the heat stress indices indicated that the danger level was very high from 0900-2000h in downtown Daegu. The daily maximum value of the WBGT was greater than or equal to $35^{\circ}C$. The differences in the heat stress indices from downtown and rural areas were higher in the daytime than at nighttime. The maximum difference was about 4 before and after 1400h, and the time variations of the heat stress indices corresponded well. Thus, we were able to confirm that the ESI and MDI can be substituted with the WBGT index.

• Journal of the Korean GEO-environmental Society
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• v.17 no.12
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• pp.65-72
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• 2016

There are numerous factors that affect stress distribution in a buried pipe, such as the shape, size, and stiffness of the pipe, its burial depth, and the stiffness of the surrounding soil. In addition, the pipe can benefit from the soil arching effect to some extent, through which the overburden and surcharge pressure at the crown can be carried by the adjacent soil. As a result, the buried pipe needs to support only a portion of the load that is not transferred to the adjacent soil. This paper presents numerical efforts to investigate the stress distribution in the buried concrete pipe under various environmental conditions. To that end, a nonlinear elasto-plastic model for backfill materials was implemented into finite element software by a user-defined subroutine (user material, or UMAT) to more precisely analyze the soil behavior surrounding a buried concrete pipe subjected to surface loading. In addition, three different backfill materials with a native soil were selected to examine the material-specific stress distribution in pipe. The environmental conditions considering in this study the loading effect and void effects were investigated using finite element method. The simulation results provide information on how the pressures are redistributed, and how the buried concrete pipe behaves under various environmental conditions.

• Animal Bioscience
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• v.36 no.2
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• pp.248-255
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• 2023

Objective: Stress factors such as high temperatures, overcrowding, and diurnal temperature range exert profound negative effects on weight gain and productivity of broiler chickens. The potential of gamma aminobutyric acid (GABA) as an excitatory neurotransmitter was evaluated under various stress conditions in this study. Methods: The experiment was conducted under four different environmental conditions: normal, high temperature, overcrowded, and in an overcrowded-diurnal temperature range. The experimental groups were divided into (-) control group without stress, (+) control group with stress, and G50 group (GABA 50 mg/kg) with stress. Weight gain, feed intake, and feed conversion ratio were measured, and stress reduction was evaluated through hematologic analysis. Results: The effects of GABA on broilers in four experimental treatments were evaluated. GABA treated responded to environmental stress and improved productivity in all the experimental treatments. The magnitude of stress observed was highest at high temperature, followed by the overcrowded environment, and was least for the overcrowded-diurnal temperature range. Conclusion: Various stress factors in livestock rearing environment can reduce productivity and increase disease incidence and mortality rate. To address these challenges, GABA, an inhibitory neurotransmitter, was shown to reduce stress caused due to various environmental conditions and improve productivity.