• 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.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.276-282
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• 2017

Purpose: This paper presents the effects of soil drought stress during the growing season and pre-harvest period on tree growth and fruit quality of "Yumi" peach, an early season cultivar. Methods: Soil drought stresses were treated with four levels of -30, -50, -60, and -70 kPa during long term (LT) and short term (ST). For LT treatments, soil water was controlled for nine weeks from May 1 to July 5, which was assumed as the full growing season. For ST treatments, soil water was controlled for four weeks from June 10 to July 5, which was assumed as the pre-harvest season. Tree growth and leaf photosynthesis were measured, and fruit characteristics such as fruit weight and diameter, soluble solid and tannin contents, and harvest date were investigated. Results: Soil water deficit treatments caused a significant reduction in tree growth, leaf photosynthesis, and fruit enlargement. LT water stress over -60 kPa during the full growing season caused significant reduction in tree growth, including shoot length, trunk girth, leaf photosynthesis, and fruit enlargement. ST water stress over -60 kPa during the pre-harvest period also induced significant reduction in leaf photosynthesis and fruit enlargement, while tree growth was not reduced. In terms of fruit quality, water stress over -50 kPa significantly reduced fruit weight, increased soluble solid and tannin contents, and delayed harvest time in both LT and ST treatments. Conclusions: As a result, it is assumed that LT water stress over -60 kPa can reduce both tree growth and fruit enlargement, whereas ST water stress over -50 kPa can reduce fruit enlargement without reducing tree growth. From an agricultural perspective, moderate water deficit like -50 kPa treatments could have positive effects, such increased fruit soluble solid contents along with minimal reduction in fruit size.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.4
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• pp.126-136
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• 2003

The B value on the saturated soil is commonly known as the amount of 1. Usually this concept is consistent with the condition that effective stress is equal to zero, but it was reported in some literatures that the B value was less than 1 in spite of saturated condition in the test of very stiff material such as rock and quasi-stiff material on which the stiffness can be mobilized because of effective stress not equal to zero. In this study the B value was measured on various effective stress conditions on normally consolidated clay. The test results in the B value less than 1 in spite of perfect saturation. The measured excessive pore water pressure was not only smaller than the change of the total stress, but also the function of time on clay.

• Nuclear Engineering and Technology
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• v.40 no.3
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• pp.239-250
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• 2008

If there is a water flow with a range of temperature inside a pipe, the wanner water tends to float on top of the cooler water because it is lighter, resulting in the upper portion of the pipe being hotter than the lower portion. Under these conditions, such thermal stratification can play an important role in the aging of nuclear power plant piping because of the stress caused by the temperature difference and the cyclic temperature changes. This stress can limit the lifetime of the piping, even leading to penetrating cracks. Investigated in this study is the effect of thermal stratification on the structural integrity of the pressurizer surge line, which is reported to be one of the pipes most severely affected. Finite element models of the surge line are developed using several element types available in a general purpose structural analysis program and stress analyses are performed to determine the response characteristics for the various types of top-to-bottom temperature differentials due to thermal stratification. Fatigue analyses are also performed and an allowable environmental correction factor is suggested.

• Proceedings of the KIEE Conference
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• 2006.07e
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• pp.23-24
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• 2006

Stator winding of hydro generator is gradually deteriorated by multi-stress and steady degradation of insulation results in insulation breakdown. The region where insulation breakdown occurs in stator winding is part where the multi-stress causes the defect of insulation material and electrical stress has been concentrated. Therefore, we judged locations of insulation breakdown to be varied according to various stress factors in service. In this paper, we drew the stator winding of hydro generators which has run for a long time and separated it into 3 parts(central part, end winding part, drawing part) according to the positions laid on the core. We performed electrical and thermal stress on these specimens for 1000 hrs under the same condition, measured the condition regularlyand analyzed the insulation status of each winding by performing partial discharge test. In addition, we analyzed the trend of partial discharge concerning specimens that caused the insulation breakdown during aging.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.3
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• pp.281-283
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• 1989

• Proceedings of the Korea Water Resources Association Conference
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• 2005.09a
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• pp.777-777
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• 2005

• Asian Journal of Turfgrass Science
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• v.25 no.2
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• pp.125-132
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• 2011

Drought is a major limiting factor in turfgrass management. Turfgrass responses to water deficit depend on the amount and the rate of water loss as well as the duration of the stress condition. This review paper was designed to understand responses such as photosynthesis, canopy spectral reflectance, plant cell, root, hormone and protein alteration when turfgrass got drought stress. Furthermore, mechanisms to recover from drought conditions were reviewed in detail. However, there are still many questions regarding plant adaptation to water deficit. It is not clear that the mechanism by which plants detect water deficit and transfer that signal into adaptive responses. Turfgrass research should focus on the best management practices such as how to enhance the ability of self-defense mechanism through understanding plant responses by environmental stress.

• Journal of Life Science
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• v.18 no.2
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• pp.154-161
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• 2008

The physiological and photochemical responses of rice seedling to NaCl stress were investigated through measuring leaf relative water content (RWC), root water uptake and chlorophyll fluorescence. When plants were exposed to increased salinity stress, the visual symptoms of injury were significant at ${\geq}$500 mM NaCl concentration for 4 and 5 day stress periods. The differences in Fv/Fm between control treatment and plants treated with 500 mM and 1,000 mM NaCl were evident after 5 day and 4 day, respectively, whereas in root water uptake its effect was observed at 500 mM and 1,000 mM NaCl at 2 day of salt-stressed periods. Leaf RWC in salt-stressed plants decreased gradually with increasing salinity in exogenous solution and duration of salt stress, and these decrease showed leaf RWC of 58-68% atduration over 2 day stress of 1,000 mM NaCl treatment and 88% at 1 day stress. NaCl stress led to a significant inhibition of the light-induced greening in etiolated rice plants, especially in 4 and 5 day salt-stressed plants, which linearly decreased with NaCl concentration ($R^2$=0.812 and 0.918, respectively). The effects of NaCl stress in rice seedlings indicate that water uptake in root is more sensitive to increasing NaCl concentration and stress duration than Fv /Fm in leaves compared with the same NaCl concentration.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.1
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• pp.1-11
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• 2016

Currently, urban green space is disappearing due to urbanization, industrialization and various environmental problems including the disruption of the ecology in urban areas. To solve such problems and increase urban green area, roof greening has been suggested as an alternative. Through observing the responses of three plant species (Mukdenia rossii, Dianthus chinensis, and Pachysandra terminalis) plantrd on the soil mixed with Geohumus, this study investigated the effect of Gehumus on soil water content and plant survival. Soil water content of the rooftop soils has been increased when mixed with Geohumus. The responses were proportional to the amount of Geohumus in the mixture. Geohumus exerted a stronger influence on raising soil moisture content for soil A which had lower water-holding capacity. The stress responses of the plants varied in relation to the amount of Geohumus and soil moisture content. The stress response was lowest for Dianthus chinensis and increased in the order of Mukdenia rossii and Pachysandra terminalis. With the highest plant stress, Pachysandra terminalis showed the lowest survival rate among the three species. Without irrigation, the plants survived only for six weeks on green roofs. The survival rate differed depending on the amount of Geohumus mixed. The results of the experiment showed, with some exceptions, that Geohumus helped to improve soil water content, reduce plant stress, and extend plant survival period.