• Title/Summary/Keyword: transport stress

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Benefical Effect of Cordyceps Sinensis Sacc. Extract (CSS) on Oxidant-Induced Membrane Tpransport Dysfunction in Rabbit Renal Cortical Slices (동충하초약침액(冬蟲夏草藥鍼液)이 가토(家兎) 신피질절편(腎皮質切片)에서 세포막물질이동계(細胞膜物質移動系)의 기능장애(機能障碍)에 미치는 영향(影響))

  • Cheon, Kap-Sool;Seo, Jung-Chul;Youn, Hyoun-Min;Song, Choon-Ho;Ahn, Chang-Beohm;Jang, Kyung-Jeon
    • Journal of Acupuncture Research
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    • v.18 no.3
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    • pp.123-133
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    • 2001
  • Objective : This study was undertaken to determine whether Cordyceps sinensis Sacc. (CSS) extract exerts the protective effect against oxidant-induced alterations in membrane transport function in renal tubules. Methods : Membrane transport fucntion was estimated by examining alterations in p-aminohippurate (PAH) uptake in rabbit renal cortical slices. For induction oxidative stress, slices were treated with an organic peroxide cumene hydroperoxide for 60 min at $37^{\circ}C$. Cumene hydroperoxide inhibited PAH uptake in a time dependent manner. Results : CSS at 0.5-5% concentrations prevented cumene hydroperoxide-induced inhibition of PAH uptake. CSS at 1% also attenuated LDH release and lipid peroxidation induced by cumene hydroperoxide. When slices were treated with 0.2 mM mercury chloride, PAH uptake was inhibited and lipid peroxidation was increased. These changes by mercury were significantly prevented by CSS. Conclusion : These results suggest that CSS prevents oxidant-induced alterations in membrane transport function in rabbit renal cortical slices. Such protective effect of CSS may be attributed to inhibition of peroxidation of membrane lipid.

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Fluid Flow and Solute Transport in a Discrete Fracture Network Model with Nonlinear Hydromechanical Effect (비선형 hydromechanic 효과를 고려한 이산 균열망 모형에서의 유체흐름과 오염물질 이송에 관한 수치모의 실험)

  • Jeong, U-Chang
    • Journal of Korea Water Resources Association
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    • v.31 no.3
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    • pp.347-360
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    • 1998
  • Numerical simulations for fluid flow and solute transport in a fracture rock masses are performed by using a transient flow model, which is based on the three-dimensional stochastic and discrete fracture network model (DFN model) and is coupled hydraulic model with mechanical model. In the numerical simulations of the solute transport, we used to the particle following algorithm which is similar to an advective biased random walk. The purpose of this study is to predict the response of the tracer test between two deep bore holes (GPK1 and GPK2) implanted at Soultz sous Foret in France, in the context of the geothermal researches.l The data sets used are obtained from in situcirculating experiments during 1995. As the result of the transport simulation, the mean transit time for the non reactive particles is about 5 days between two bore holes.

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Nanoprobing Charge Transport Properties of Strained and Indented Topological Insulator

  • Hwang, Jin Heui;Kwon, Sangku;Park, Joonbum;Lee, Jhinhwan;Kim, Jun Sung;Lyeo, Ho-Ki;Park, Jeong Young
    • Proceedings of the Korean Vacuum Society Conference
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    • 2013.08a
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    • pp.128.1-128.1
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    • 2013
  • We investigated the correlation between electrical transport and mechanical stress in $Bi_2Te_2Se$ by using a conductive probe atomic force microscopy in an ultra-high vacuum environment. Uniform distribution of measured friction and current were observed over a single quintuple layer terrace, which is an indication of the uniform chemical composition of the surface. By measuring the charge transport of $Bi_2Te_2Se$ surface as a function of the load applied by a tip to the sample, we found that the current density varies with applied load. The variation of current density was explained in light of the combined effect of the changes in the in-plane conductance and spin-orbit coupling that were theoretically predicted. We suppose that the local density of states is modified by tip-induced strain, but topological phase still remains. We exposed a clean topological insulator surface by tip-induced indentation. The surface conductance on the indented $Bi_2Te_2Se$ surface was studied, and the role of surface oxide on the surface conductance is discussed.

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Analysis of flow Field in a steam turbine LP/HP Bypass control Valve (증기터빈 Bypass Valve 의 유동장 해석)

  • Choi, Ji-Yong;Kim, Kwang-Yong
    • 유체기계공업학회:학술대회논문집
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    • 2005.12a
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    • pp.437-440
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    • 2005
  • In the present work, characteristics of the flow in CAGE of a steam turbine LP/HP Bypass control valve for thermal power plant are investigated. The flow field is analyzed numerically by solving steady three-dimensional Reynolds-averaged Navier-Stokes equations. Shear stress transport (SST) model is used as turbulence closure.

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Analysis of turbulent heat transfer over V-shaped ribs (V-형 사각리브에 의한 난류열전달 해석)

  • Lee, Young-Mo;Kim, Kwang-Yong
    • 유체기계공업학회:학술대회논문집
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    • 2005.12a
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    • pp.169-172
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    • 2005
  • Numerical analysis of turbulent flow in three-dimensional channel with V-shaped ribs extruded on both walls has been carried out. Reynolds-averaged Navier-Stokes are calculated for analysis of fluid flow and heat transfer. Shear stress transport (SST) turbulence model is used as a turbulence closure. Computational results for heat transfer rate show good agreements with experimental data.

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자기부상열차의 공력 특성에 관한 수치 연구

  • Won, Seong-Sik;U, Dae-Cheon
    • Proceeding of EDISON Challenge
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    • 2016.11a
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    • pp.55-57
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    • 2016
  • 본 연구에서는 초고속 자기부상열차의 단면도를 통하여 2-D형상을 모델링하고 이를 기반으로 항력과 유동 특성에 대한 분석을 수행하였다. 유동의 마하수가 0.3 이상임을 고려하여 압축성 모델이 사용되었고, 난류모델은 Menter's k-w SST(Shear Stress Transport)모델을 적용시켰다. 2-D 해석과 자기부상열차의 특성상 열차가 공기중에서 주행하고 있는 것으로 가정하고 공력 특성을 해석하였다.

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Rice Iron Metabolism: from Source to Solution

  • Santos, Livia Scheunemann dos;Oliveira, Antonio Costa de
    • Journal of Crop Science and Biotechnology
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    • v.10 no.2
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    • pp.64-72
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    • 2007
  • Iron is an important micronutrient for plants. Iron metabolism is a complex mechanism under a delicate balance. Iron metabolism represents two major problems for plants: deficiency as a consequence of solubility problems and toxicity due to excess solubility in anaerobic conditions. In the last few years, new genes have been discovered that influence iron uptake, transport and storage. Irrigated rice is exposed to high levels of $Fe^{II}$, normally rare in aerobic soil conditions. The implications of altering iron uptake rates and the effects of newly discovered genes are discussed.

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Analysis of Thermal Performance in a Micro Flat Heat Pipe with Axially Trapezoidal Groove (그루브형 마이크로 히트파이프의 열전달특성에 대한 연구)

  • Suh, Jeong-Se
    • Proceedings of the KSME Conference
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    • 2001.06d
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    • pp.360-364
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    • 2001
  • Numerical Aanlysis is made on the thermal performance of micro heat pipe in a axial flat grooved channel. The flow of liquid and vapor is investigated in trapezoidal grooves and the effect of variable shear stress along the interface of the liquid and vapor considered. The results from this study are obtained in the axial variation of pressure difference between vapor and liquid, contact angle, velocity of liquid and vapor and so forth. In addition, maximum heat transport capacity of micro-heat pipe is provided by varying the operation temperature, and compared with that from Schneider and Devos's model in which the interfacial shear stress is neglected.

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Study on Characteristics of Displacement and Stress of Piers under Adjacent load

  • Song, Bo;Zhang, Jingxing;Zhang, Zunke;Wang, Yanxuc;Kim, Taehwan
    • Journal of the Society of Disaster Information
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    • v.12 no.1
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    • pp.40-46
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    • 2016
  • Nowdays, adjacent loading bringing enormous harm to the existing bridge in engineering construction. In this paper, the influencing mechanism of adjacent loading to pier and Law of displacement of pier is researched through living examples, and the safe influence area has been defined. Research shows that: the main damages to piers is caused by the side loading; lateral displacement index of pier top surface is more conservative than the pier additional stress index; it is secure when the distance of adjacent load is 0.5 times of the height of accumulation or 6m, otherwise it would be very scary, and the monitoring measure is necessary.

EVALUATION OF TURBULENCE MODELS FOR ANALYSIS OF THERMAL STRIPING (Thermal Striping 해석 난류모델 평가)

  • Cho, Seok-Ki;Kim, Se-Yun;Kim, Seong-O
    • Journal of computational fluids engineering
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    • v.10 no.4 s.31
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    • pp.1-11
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    • 2005
  • A numerical study of the evaluation of turbulence models for thermal striping phenomenon is performed. The turbulence models chosen in the present study are the two-layer model, the shear stress transport (SST) model and the V2-f model. These three models are applied to the analysis of the triple-jet flow with the same velocity but different temperatures. The unsteady Reynolds-averaged Navier-Stokes (URANS) equation method is used together with the SIMPLEC algorithm. The results of the present study show that the temporal oscillation of temperature is predicted by the SST and V2-f models, and the accuracy of the mean velocity, the turbulent shear stress and the mean temperature is a little dependent on the turbulence model used. In addition, it is shown that both the two-layer and SST models have nearly the same capability predicting the thermal striping, and the amplitude of the temperature fluctuation is predicted best by the V2-f model.