• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.3
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• pp.257-264
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• 1995

Various factors are investigated on the bed load transport driven by waves and current, and proper forms of bed load transport formulas mainly used in river hydraulics are chosen for the estimation of combined flow bed load transport after considering the additional factors. The BYO Model is employed for the computation of maximum bed shear stress and mean bed shear stress of the combined flow. The friction factor of uni-directional flow is estimated by using modified Keulegan equation, and equivalent roughness height is determined by obtaining correct answer for the bed shear stress of uni-directional flow. Empirical constant in each bed load formula is determined by applying it to Bijker's laboratory data of bed load transport by waves and current and the formulas obtained are discussed on their final forms with the values of empirical constants.

• Korean Journal of Veterinary Service
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• v.26 no.2
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• pp.185-191
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• 2003

There was a mass outbreak of death caused by transport stress and malnutrition in Japanese macaques imported from Japan at a farm stock in Korea, which were diagnosed on the ground of history taking, clinical finding, hematological examination and necropsy. Twenty eight Japanese macaques imported from Japan died suddenly from the 4th day after arrival in a farm. These animals were confined very small cages individually and lose the appetite for 10 days from shipping. Main clinical findings observed from alive Japanese macaques consisted of hypothermia and dehydration. On hematological observation for typical 4 cases showed increased erythrocytes and packed cell volume. On serum biochemical examination for 3 cases showed hypoglycemia, whereas blood urea nitrogen, aspartate aminotransferase and alanine aminotransferase were increased. On necropsy for 3 cases, hemorrhage and congestion were observed on the lung and the walls of stomach and intestine were thinned. Histologically, hemorrhagic pneumonia and enteritis with loss of villi were seen. The death of these animal was caused by poor management during transport, which was resulted in transport stress and malnutrition.

• Biomolecules & Therapeutics
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• v.17 no.2
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• pp.175-180
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• 2009

Taurine is the most abundant free amino acid in the retina and transported into retina via taurine transporter (TauT) at the inner blood-retinal barrier (iBRB). In the present study, we investigated whether the taurine transport at the iBRB is regulated by oxidative stress or disease-like state in a conditionally immortalized rat retinal capillary endothelial cell line (TR-iBRB) used as an in vitro model of iBRB. First, [$^3H$]taurine uptake and efflux by TR-iBRB were regulated in the presence of extracellular $Ca^{2+}$. [$^3H$]Taurine uptake was inhibited and efflux was enhanced under $Ca^{2+}$ free condition in the cells. In addition, oxidative stress inducing agents such as tumor necrosis factor-$\alpha$ (TNF-$\alpha$), lipopolysaccharide (LPS), diethyl maleate (DEM) and glutamate increased [$^3H$]taurine uptake and decreased [$^3H$]taurine efflux in TR-iBRB cells. Whereas, 3-morpholinosydnonimine (SIN-1), which is known to NO donor decreased [$^3H$]taurine uptake. Lastly, TR-iBRB cells exposed to high glucose (25 mM) medium and the [$^3H$]taurine uptake was reduced about 20% at the condition. Also, [$^3H$]taurine uptake was decreased by cytochalasin B, which is known to glucose transport inhibitor. In conclusion, taurine transport in TR-iBRB cells is regulated diversely at extracellular $Ca^{2+}$, oxidative stress and hyperglycemic condition. It suggested that taurine would play a role as a retinal protector in diverse disease states.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.6
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• pp.600-606
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• 2009

In this paper, the coupled model with hydrogen transport and elasto-plasticity behavior is introduced. This model is implemented to the general-purpose FE code, ABAQUS, via the user-defined subroutine UMAT and UMATHT. In UMAT, the spatial gradients of hydrostatic stress and hydrogen induced deformation are calculated, and then are passed into UMATHT. Heat transfer equation within UMATHT is substituted by hydrogen transport equation including the effects of stress states and strain hardening. To validate this model, the finite element analyses coupled with hydrogen transport and mechanical loading are performed for the boundary layer specimens with low and high strength steel properties. The FE results are compared with the previous studies by Taha and Sofronis (2001).

• Water for future
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• v.19 no.3
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• pp.239-248
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• 1986

Monthly wind stress, wind stress curl and volume transport stream functions are computed in the Eastern Sea(Japan Sea) based upon observed wind and atmospheric pressure data respectively. The presented two results show different distributios on locality and season but as common features the results reveal the northwesterly surface wind stress \ulcorner 새 the monsoon in winter, south to southwesterly wind stress \ulcorner 새 the southerly wind in summer and strond anticyclonic curl in the northern part on the Eastern Sea(Japan Sea) in winter. In the distributions obtained from the sea level atmospheric pressure data, the maximum value of the wind stress and of curls of small scales are shown off the southeast coast of Siberia and northeast coast of Korea. Volume transport distributions obtained from the Sverdrup relationship suggest that the strong northward boundary current can be formed along the northeast coast of Korea in winter and weak southward boundary current in summer.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.418-421
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• 2007

Using gridded wind-stress products constructed by satellite scatterometers (ERS-1, 2 and QSCAT) data and those by numerical weather prediction(NWP) model(NCEP-reanalysis), we estimate wind-driven transports of the North Pacific subtropical gyre, and compare them in the central portion of the gyre (around 300 N) with geostrophic transports calculated from historical hydrographic data (World Ocean Database 2005). Even if there are some discrepancies between the wind-driven transports by the QSCAT and NCEP products, they are both in good agreement with the geostrophic transports within reasonable errors, except for the regional difference in the eastern part of the zone. The difference in the eastern part is characterized by an anticyclonic deviation of the geostrophic transport resulting from an anti-cyclonic anomalous flow in the surface layer, suggesting that it is related to the Eastern Gyral produced by the thermohaline process associated with the formation of the Eastern Subtropical Mode Water. We also examine the consistency of the Sverdrup transports estimated from these products by comparing them with the transports of the western boundary current, namely the Kuroshio regions, in previous studies. The net southward transport, based on the sum of the Sverdrup transports by QSCAT and NCEP products and the thermohaline transport, agrees well with the net northward transport of the western boundary current, namely the Kuroshio transport. From these results, it is concluded that the Sverdrup balance can hold in the North Pacific subtropical gyre.

• Corrosion Science and Technology
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• v.21 no.4
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• pp.243-249
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• 2022

The objective of the present study was to perform failure analysis of double-layered bellow (expansion joint), a core part of stress reliever, used to relieve axial stresses induced by thermal expansion of heat-transport pipes in a district heating system. The bellow underwent tensile or compressive stresses due to its structure in terms of position. A leaked position sufferred a fatigue with a tensile component for decades. A cracked bellow contained a higher fraction of martensitic phase because of manufacturing and usage histories, which induced more brittleness on the component. Inclusions in the inner layer of the bellow acted as a site of stress concentration, from which cracks initiated and then propagated along the hoop direction from the inner surface of the inner layer under fatigue loading conditions. As the crack reached critical thickness, the crack propagated to the outer surface at a higher rate, resulting in leakage of the stress reliever.

• Bulletin of the Korean Chemical Society
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• v.24 no.2
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• pp.178-182
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• 2003

The stress and the heat-flux auto-correlation functions in the Green-Kubo formulas for shear viscosity and thermal conductivity have non-decaying long-time tails. This problem can be overcome by improving the statistical accuracy by N (number of particles) times, considering the stress and the heat-flux of the system as properties of each particle. The mean square stress and the heat-flux displacements in the Einstein formulas for shear viscosity and thermal conductivity are non linear functions of time since the quantities in the mean square stress and the heat-flux displacements are not continuous under periodic boundary conditions. An alternative to these quantities is to integrate the stress and the heat-flux with respect to time, but the resulting mean square stress and heat-flux displacements are still not linear versus time. This problem can be also overcome by improving the statistical accuracy. The results for transport coefficients of liquid argon obtained are discussed.

• Journal of the Korean GEO-environmental Society
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• v.10 no.1
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• pp.5-14
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• 2009

This study is to analyze numerically the spatial behaviors of the solute transport in a spatially correlated variable-aperture fracture under the effective normal stress conditions. Numerical results show that the solute transport in a fracture is strongly affected by the spatial correlation length of apertures and applied effective normal stress. According to increasing spatial correlation length, the mean residence time of solute is decreased and the tortuosity and Peclet number (is a dimensionless number relating the rate of advection of a flow to its rate of diffusion) is also decreased. These results mean that the geometry of the aperture distribution is favorable to the solute transport as the spatial correlation length is increased. However, according to the applied effective normal stress is increased, the mean residence time and tortuosity have a tendency to increase but the Peclet number is decreased. The main reason that the Peclet number is decreased, is that the solute is displaced by one or two channels with relatively higher local flow rate due to the increment of contact areas by increasing effective normal stress. Moreover, based on numerical results of the solute transport in this study, the exponential-type correlation formulae between the mean residence time and the effective normal stress are proposed.

• Biomolecules & Therapeutics
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• v.10 no.2
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• pp.99-103
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• 2002

Taurine has a neuroprotective action from oxidative stress in neural cell. In the present study, we studied taurine transport under basal and stressed conditions in conditionally immortalized rat brain capillary endothelial cell line (TR-BBB13) in vitro. The uptake of[$^3{H}$]taurine in the TR-BBB13 was increased by time-dependently and dependent on both Na$^{+}$ and Cl/ sup -/. Furthermore, $\beta$-alanine strongly inhibited the uptake of [TEX>$^3{H}$]taurine in the TR-BBB13. To study the effcts of oxidative stress on taurine transport, we used diethyl maleate (DEM) and lipopolysccharide (LPS). Diethyl maleate (DEM, $300\Mu\textrm{M}$) significantly reduced uptake of [TEX>$^3{H}$]taurine by time-dependently until 8 hr exposure in TR-BBB 13. But, the [TEX>$^3{H}$]taurine uptake was not changed by lipopolysccharide (LPS, 10 ng/ml) in TR-BBB13.3.