• Journal of the Korean Applied Science and Technology
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• v.32 no.3
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• pp.412-417
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• 2015

The purpose of this study is to treat the ballast water by shear stress without an environmental pollution and to find out the optimal treatment conditions. The ballast water problem is issued up as the trade activated and the cargos mobilized. To improve this problem, International Marine Organization(IMO) make the rule about the ballast water treatment with specific restrictions. Although many countries have been studying about the ballast water treatment technology, there is almost no technology that can treat the microorganisms under $50{\mu}m$ without any secondary pollution. In this study, we tried to treat ballast water by applying shear stress as the physical treatment for the sterilization and tried to find out the optimal conditions including the 100% sterilizing rate and the best economic condition.

• Journal of Ecology and Environment
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• v.29 no.6
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• pp.581-584
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• 2006

The tissue water relation parameters were compared to assess the resistance of representative three gardening tree species to water stress. Zelkova serrata showed a strong resistant characteristics to water stress compared to Betula platyphylla var. japonica and Liriodendron turipifera. Turgor pressure at turgor loss point in Z. serrata was -2.54 MPa, whereas those of 5. platyphylla var, japonica and L. turipifera were -2.24 and -2.03, respectively. In addition, Z. serrata showed less reduction in pressure potential to decrease of free water content in the leaf tissue, indicating effective shrinking of the cell wall compared to others. On the other hand, L. turipifera indicated a weak resistance to water stress, which has low turgor potential at turgor loss point and cell wall elasticity. These results suggest that Z. serrata would be suitable for relatively dry conditions of location and humid conditions of location would be suitable for L. dendronas plantation.

• Geomechanics and Engineering
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• v.13 no.6
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• pp.1011-1025
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• 2017

The geological conditions surrounding the Jijiapo Tunnel of the Three Gorges Fanba Highway project in Hubei Province are very complex. In this paper, a 3-D physical model was carried out to study the evolution process of filling-type fracture water inrush and mud gush based on the conditions of the section located between 16.040 km and 16.042 km of the Jijiapo Tunnel. The 3-D physical model was conducted to clarify the effect of the self-weight of the groundwater level and tunnel excavation during water inrush and mud gush. The results of the displacement, stress and seepage pressure of fracture and surrounding rock in the physical model were analyzed. In the physical model the results of the model test show that the rock displacement suddenly jumped after sustainable growth, rock stress and rock seepage suddenly decreased after continuous growth before water inrushing. Once water inrush occured, internal displacement of filler increased successively from bottom up, stress and seepage pressure of filler droped successively from bottom up, which presented as water inrush and mud gush of filling-type fracture was a evolving process from bottom up. The numerical study was compared with the model test to demonstrate the effectiveness and accuracy of the results of the model test.

• Korean Journal of Environmental Agriculture
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• v.17 no.4
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• pp.335-340
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• 1998

This study was conducted to determine the morphological responses of barley seedlings to NaCl stress and to investigate histological changes of cells with transmission electron microscope(TEM) after NaCl stress. Plant height and root length of 10-day old barley seedlings with NaCl stress were reduced and inhibition level was found to be more severe in the plant height than in the root length. The leaf length, leaf width and leaf area were shorter as well with NaCl stress than without NaCl stress. However, there was no difference in the number of roots between NaCl treatments. The weight of dry matter decreased at higher NaCl concentrations, especially at 100mM NaCl. The water content of shoots tend to decrease at higher NaCl concentrations, but there was no difference in the water content of roots, The reduced sugar content was greatly increase than starch. Cellulose content was higher in NaCl stressed-plant than control, and tended to decreased at higher NaCl concentrations. Lignin content also decreased NaCl stressed-plant but there was no tendency at NaCl stress concentrations. Electric conductivity of cell sap with seedlings was high with NaCl stressed-plant. Amount of cell sap gradually increased with time in the roots than in the shoots, The grana of chloroplasts was changed by 150mM NaCl concentration. The christe of mitochondria in root meristematic sells ruined in structure and cell wall of leaf and root was also ruined by NaCl stress.

• Stress
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• v.25 no.4
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• pp.239-245
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• 2017

Background: A quasi-experimental study with non-equivalent control groups was performed to determine an effect of aromatherapy foot bath on stress and autonomic nervous activity. Methods: To confirm the effect of aromatherapy foot bath, aromatherapy foot bath group was asked to have a bathing by dropping 0.5 cc in 18 L water after blending with a ratio of 6:3:1 with essential oil lavender, lemon, and tea tree and a foot bath group was asked for bathing only by water. Results: Aromatherapy foot bath group showed significant decrease in subjective stress score (t=3.465, p=0.001) and stress index (t=3.021, p=0.004) in addition to simultaneous increase in sympathetic nervous activity (t=-2.913, p=0.005). However, no significant stimulation of parasympathetic nervous system was observed (t=-1.831, p=0.072). Conclusions: As aromatherapy foot bath is a possible effective intervention for stress relief, it can be applied as an effective method to relieve the stress for healthy adults and patients.

• Geomechanics and Engineering
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• v.38 no.3
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• pp.215-229
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• 2024

Because of the various patterns of deep-water inrush and complicated mechanisms, accurately predicting mine water inflows is always a difficult problem for coal mine geologists. In study presented in this paper, the water inrush channels were divided into four basic water diversion structures: aquifer, rock fracture zone, fracture zone and goaf. The fluid flow characteristics in each water-conducting structure were investigated by laboratory tests, and multistructure and multisystem coupling flow analysis models of different water-conducting structures were established to describe the entire water inrush process. Based on the research of the water inrush flow paths, the analysis model of different water inrush space structures was established and applied to the prediction of mine water inrush inflow. The results prove that the conduction sequence of different water-conducting structures and the changing rule of permeability caused by stress changes before and after the peak have important influences on the characteristics of mine water-gushing. Influenced by the differences in geological structure and combined with rock mass RQD and fault conductivity characteristics and other mine exploration data, the prediction of mine water inflow can be realized accurately. Taking the water transmitting path in the multistructure as the research object of water inrush, breaking through the limitation of traditional stratigraphic structure division, the prediction of water inflow and the estimation of potentially flooded area was realized, and water bursting intensity was predicted. It is of great significance in making reasonable emergency plans.

• Proceedings of the KSEG Conference
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• 2003.04a
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• pp.131-135
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• 2003

In order to investigate the influence of surrounding environment on strength of rock, the uniaxial compression test under non-atmospheric environments was conducted on Kumamoto andesite. The environments used in this study are water vapor, organic vapor environments as methanol, ethanol and acetone and inorganic gas environments as oxygen, nitrogen and argon. From the experimental results, it is clarified that water is the most effective agent which promotes stress corrosion of rock. Furthermore, the strength of rock increases with decreasing water vapor pressure. From the relation between uniaxial compressive strength and water vapor pressure, the stress corrosion index of Kumamoto andesite is estimated 24.

• Journal of Korea Water Resources Association
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• v.31 no.1
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• pp.115-120
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• 1998

In this paper, a depth-averaged two-dimensional transport model is introduced, and its error bound is presented as the results of sensitivity analysis. The results show that the calculated SS concentration is highly dependant on Manning roughness coefficient, mixing coefficient. fall velocity. and critical shear stress. On the other hand, water level and dispersion coefficient are proved to be less significant in the variation of SS concentration.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1997.04a
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• pp.79-86
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• 1997

In this study, pre-postprocessing toolbox is developed to perform elasto-plastic analyze of underground structures with transient ground water flow. This toolbox is composed of three modules. The first is the data input processor for the structural analysis. The preprocessing Is using GUI (Graphic User Interface), which is consist of dialog box, pull down, and short-cut icon, etc. The second is the structural analysis module. The analysis is based on the elasto-plastic finite element method involving additional options such as ground excavation effect, transient ground water flow, and rock bolts behavior. The last is the postprocessing module. The postprocessing is able to verify the result of the structural analysis by the graphical simulation which visualizes the element mesh, the node displacements, the element stress states, the stress contour, the ground water surface, and the rock bolt stresses. Since various options are considered separately in this toolbox, it is easy to modify the module of each processing, and to update other functional modules for the given analysis conditions.

• Journal of Korean Society on Water Environment
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• v.28 no.2
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• pp.213-218
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• 2012

Abnormal dissolved oxygen concentration in aquatic habitat, both depletion and supersaturation, can be stress factor to aquatic animals. In this study the nationwide distribution of oxygen supersaturation was analyzed for three categories of streams (43 urban streams, 15 rural streams, and 14 forest streams) by using monitoring network data of the Korean Ministry of Environment. From the distribution analysis 30% of urban streams showed hyperoxic condition of eutrophic level, while no forest stream showed hyperoxic condition. The physiological effect of hyperoxia on fish was examined using two species of fish Zacco koreanus, which resulted in higher concentration of a stress hormone (cortisol) in fish exposed to hyperoxic concentration (196%) of oxygen. This study shows that hyperoxic condition is ubiquitous in urban and rural Korean streams, and it can be a stress factor to aquatic animals.