• Childhood Kidney Diseases
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• v.13 no.2
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• pp.99-117
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• 2009

Diabetic nephropathy is a major cause of chronic renal failure in developing countries, and the prevalence rate has markedly increased during the past decade. Diabetic nephropathy shows various specific histological changes not only in the glomeruli but also in the tubulointerstitial region. In the early stage, the effacement of podocyte foot processes and thickened glomerular basement membrane (GBM) is noticed even at the stage of microalbuminuria. Nodular, diffuse, and exudative lesions, so-called diabetic glomerulosclerosis, are well known as glomerular lesions. Interstitial lesions also exhibit fibrosis, edema, and thickened tubular basement membrane. Diabetic nephropathy is considered to be multifactorial in origin with increasing evidence that one of the major pathways involved in the development and progression of diabetic nephropathy as a result of hyperglycemia. Hyperglycemia induces renal damage directly or through hemodynamic alterations, such as, glomerular hyperfiltration, shear stress, and microalbuminuria. Chronic hyperglycemia also induces nonhemodynamic dysregulations, such as, increased production of advanced glycosylation endproducts, oxidative stress, activation of signal pathway, and subsequent various cytokines. Those pathogenic mechanisms resulted in extracellular matrix deposition including mesangial expansion and GBM thickening, glomerular hypertrophy, inflammation, and proteinuria. In this review, recent opinions on the histopathologic changes and pathophysiologic mechanisms leading to initiation and progression of diabetic nephropathy will be introduced.

• International Journal of Vascular Biomedical Engineering
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• v.1 no.1
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• pp.32-40
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• 2003

Axillo-bifemoral (Ax-Fem) bypass are now well accepted for bilateral iliac artery occlusion as the second best option. This extra-anatomical (unnatural) bypasses, however, have various hemodynamic liabilities affecting the patency. Hemodynamic conditions of each different type of Ax-Fem bypass were assessed with computer simulation model to determine the hemodynamically more sound type. Simulation models of five different types of Ax-Fem bypass were constructed. Our investigation based on the computer simulation models have shown distinct differences between two most popular Lazy-S type and Inverted-C type on the distribution of flow volume, shear stress and recirculation zone, etc., though both types have shown similar clinical results. Lazy-S type has shown better hemodyanmic status than inverted-C type. The theoretical advantage of "Lazy-S" type has never been adequately proved for its superiority clinically over the inverted-C type. Inverted-C type is now in more favor with clinically better results in spite of many hemodynamic liabilities including retrograde flow to the branching graft. The improvement of over-all long-term patency rate of various extra-anatomical bypasses is still warranted through proper correction of the hemodynamic liability. Even though clinical outcome of the extra-anatomical bypass has been equal regardless of the type of crossover femoral graft configuration, there are distinct differences on the hemodynamic characteristics among various types of configuration. Further hemodynamic study in the pulsatile flow status is warranted to correct hemodynamic defects with proper modification of various hemodynamic factors of each model.

• Korean Journal of Food Science and Technology
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• v.22 no.2
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• pp.111-115
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• 1990

The rheological properties of soybean paste suspensions as affected by concentrations and heating were studied. All suspensions of soybean paste showed thioxotropic plastic behavior. The concentrated suspensions below the ratio of water to soybean paste, 1.25 exhibited Figure-eight phenomena which were presented by two Intersections of the up curve with the dorm curve of shear rate. The dilute suspension (soybean paste: water=1:2) showed H type hysteresis loop at low temperature. But increasing the heating temperature above $60^{\circ}C$, the hysteresis loop exhibited a Figure eight phenomenon. Consistency index of the suspensions increased remarkably by heating and showed the highest value around isoelectric point of the protein. It was suggested that the proteinous nitrogen might be the main component taking part in viscous behavior under different pH and heat treatment.

• Structural Engineering and Mechanics
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• v.74 no.6
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• pp.723-735
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• 2020

This study is reported the adhesion failure in adhesive bonded composite and specifically for the T-joint structure. Three-dimensional finite element analysis has been performed using a commercial tool and the necessary outcomes are obtained via an eight noded solid element (Solid 185-element) from the library of ANSYS. The structural analysis input has been incurred through ANSYS parametric design language (APDL) code. The normal and shear stress distributions along different layers of the joint structure have been evaluated as the final outcomes. Based on the stress distributions, failure location in the composite joint structure has been identified by using the Tsai-Wu stress failure criterion. It has been found that the failure index is maximum at the interface between flange and web part of the joint (top layer) which indicates the probable location of failure initiation. This kind of failures are considered as adhesion failure and the failure propagation is governed by strain energy release rate (SERR) of fracture mechanics. The different adhesion failure lengths are also considered at the failure location to calculate the SERR values i.e. mode I fracture (opening), mode II fracture (sliding) and mode III fracture (tearing) along the failure front. Also, virtual crack closure technique (VCCT) principle of fracture mechanics steps is used to calculate the above said SERRs. It is found that the mode I SERR is more dominating compared to other two modes of failure for the joint considered. Finally, the influences of various parametric (geometrical and material) effect on SERR of the joint structure are evaluated and discussed in details.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.1
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• pp.69-75
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• 2009

This paper studies the aerodynamic performance that the vent mixer-new conceptual supersonic mixer-showed with its geometric characteristics. The hole is 2 mm with 2 mm's distance from the wall in case 1 and with no distance in case 2. In case 3 die hole is 1 mm. Case 1 and case 2 showed the same total pressure recovery ratio, of which the case 3 was lower than that. While cases 1-3 had the same reattachment length, the shear layer was thicker in cases 1 and 2 than in case 3. Within the recirculation zone, cases 1 and 2 had lower pressure loss and higher velocity gradient difference than case 3-they enhance mixing between air and fuel. Separation bubble which is developed by the inflow into the recirculation zone has a significant effect on the total pressure recovery ratio in the combustor. Also separation bubble influences pressure distributions and recirculation flows in the recirculation zone. Therefore, inflow rate of air into the recirculation zone mainly affects the performance of vent mixer.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.40 no.1
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• pp.1-7
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• 2007

The chemical and rheological properties of deproteinated porphyrans from laver Porphyra yezoensis were investigated to obtain basic data for the production of food materials with biological functionality. Deproteinated porphyran was prepared by acid extraction (pH 4.0, $80^{\circ}C$, 4 hr) and successive hydrolysis with 0.5% Alcalase and 0.5% Flavourzyme. The porphyran constituted 10.7% of the dry laver and consisted of 0.6% protein, 14.8% ester sulfate, 3.2% 6-O-methyl galactose, 16.0% 3,6-anhydro-L-galactose, and 67.3% galactose. The effects of concentration and temperature on the apparent viscosity were examined by applying the power law and Arrhenius equations. The porphyran solution showed the typical behavior of a pseudoplastic liquid and the flow behavior index decreased with increasing concentration. The activation energy of the deproteinated porphyran solution at a 1,000 L/s shear rate also increased from $1.4954{\times}10^{4}\;to\;1.9544{\times}10^{4}\;J/kg$ mol with the concentration.

• Geomechanics and Engineering
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• v.12 no.4
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• pp.611-626
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• 2017

The research reported herein is concerned with the model testing of piles socketed in soft rock which was simulated by cement, plaster, sand, water and concrete hardening accelerator. Model tests on a single pile socketed in simulated soft rock under axial cyclic loading were conducted and the bearing capacity and accumulated deformation characteristics under different static, and cyclic loads were studied by using a device which combined oneself-designed test apparatus with a dynamic triaxial system. The accumulated deformation of the pile head, and the axial force, were measured by LVDT and strain gauges, respectively. Test results show that the static load ratio (SLR), cyclic load ratio (CLR), and the number of cycles affect the accumulated deformation, cyclic secant modulus of pile head, and ultimate bearing capacity. The accumulated deformation increases with increasing numbers of cycles, however, its rate of growth decreases and is asymptotic to zero. The cyclic secant modulus of pile head increases and then decreases with the growth in the number of cycles, and finally remains stable after 50 cycles. The ultimate bearing capacity of the pile is increased by about 30% because of the cyclic loading thereon, and the axial force is changed due to the applied cyclic shear stress. According to the test results, the development of accumulated settlement is analysed. Finally, an empirical formula for accumulated settlement, considering the effects of the number of cycles, the static load ratio, the cyclic load ratio and the uniaxial compressive strength, is proposed which can be used for feasibility studies or preliminary design of pile foundations on soft rock subjected to cyclic loading.

• Journal of the Korean Graphic Arts Communication Society
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• v.26 no.1
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• pp.39-50
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• 2008

We have manufactured Ag pastes for gravure printing by adding different solvent contents. Then the gravure printability and properties of conductive patterns gravure-printed by the different rheology characteristics of pastes were investigated. The dispersity of pastes was increased and the viscosity and shear rate dependence of viscosity for pastes were decreased by increasing the solvent content. Also storage modulus G', loss modulus G" and angular frequency value when G" starts to be bigger than G' of pastes were increased by decreasing the solvent content. These mean a flow drop of paste. As a result of gravure printing using two plates which have different line counts(175line and 350line), conductive patterns printed using 175line were spreaded more but Ag packing, thickness and conductivity of the conductive patterns were better than those printed using 350line. And the spread values of conductive patterns were increased with solvent contents but the best properties for Ag packing, surface roughness and conductivity of the conductive pattern were obtained by paste (3) which has 550cps of viscosity at $100s^{-1}$ and tan ${\delta}$ > 1 at 10rad/s. As a result of gravure printing using 350 line plate and paste (3), the conductive pattern has $1.2{\mu}m$ of film thickness and $1.9{\times}10^{-5}{\Omega}{\cdot}cm$ of conductivity.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.545-550
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• 2017

When the systolic blood pressure is high, intermittent turbulence in blood flow appears in the aorta and carotid artery with stenosis during the systolic period. The turbulent blood flow is difficult to analyze using the Newtonian turbulence model due to the viscous characteristics of blood flow. As the shear rate is increased, the blood viscosity decreases by the viscoelastic properties of blood and a drag reduction phenomenon occurs in turbulent blood flow. Therefore, a new non-Newtonian turbulent model is required for viscoelastic fluid and hemodynamics. The main aims of this study were to develop a non-Newtonian turbulence model using the drag reduction phenomenon based on the standard $k-{\varepsilon}$ turbulent model for a general non-Newtonian fluid. This was validated with the experimental data and has a good tendency for non-Newtonian turbulent flow. In addition, the computation time and resources were lower than those of the low Reynolds number turbulent model. A modified turbulent model was used to analyze various turbulent blood flows.

• Journal of Soil and Groundwater Environment
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• v.6 no.1
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• pp.53-62
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• 2001

Effects of surface defect on thermal stability and stress crack resistance of high density polyethylene geomembranes in environmental conditions were examined by comparing the mechanical properties, chemical resistance and failure times of geomembranes between defective cases under different temperatures. Artificial surface defects were added to the surface of geomembranes by scratch apparatus designed specially. The number of surface defects was increased with the smaller size of scratch induced particles, and the more scratch addition numbers at the shear rate of scratch induced mechanism, 100mm/min. The tensile strength were decreased but the tensile strain was increased with the above conditions. In chemical resistance of defective geomembranes, the tensile strength were decreased but the tensile strain was increased with the longer immersion period and the higher temperature under the same scratch induced conditions. Finally, failure times of defective geomembranes by ESCR test were shifted to the shorter time ranges by increasing temperatures.