• Title/Summary/Keyword: effective diffusion

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Can herbal extracts be used as skin penetrating agent

  • Chung, Leung Ping;Xin, Zhao;Tak, Law Wai;David, Lau Tai Wai
    • Advances in Traditional Medicine
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    • v.7 no.3
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    • pp.211-216
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    • 2007
  • Swollen and painful extremities have been treated with herbal baths in attempts to alleviate the symptoms. A popular herbal bath used in China, contains a component called 'bone-penetrating herb' which is believed to facilitate the penetration of herbal substances across the skin to the swollen site, so swollen site, so that pain and swelling will be improved. A search from the Chinese pharmacopedia revealed that 22 different herbs have been traditionally used as 'bone-penetrating herb'. Five of these herbs were available in market and were chosen for experimental studies. Standard diffusion experiments were done to identify the most effective herb among the five, in the penetration facilitation. Glechoma longituba at a concentration of 20% was found to give the best results in the facilitation of Bromophenol blue diffusion across artificial and biological membranes. When compared with one commonly used diffusion facilitator, viz. azone, azone was found to be more effective than glechoma longituba. The encouraging observations support future studies on the basic science behind the use of herbal components as topical agents to treat pain and swelling.

A study on the stress dependence of diffusion coefficient at the elevated tenperature and the structural characterictics of 12% Cr rotor steel. (12% Cr강의 고온 확산계수의 응력의존성과 조직의 특성에 관한 연구)

  • 장윤석;김태형
    • Journal of Ocean Engineering and Technology
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    • v.11 no.2
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    • pp.39-47
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    • 1997
  • Creep rate the elevated temperature is known to be controller by the softening process of microstructure especially in the solid solution alloys such as 125 Cr rotor steel. The change of structure is a decreasing process of the free energy of the state including stress, diffusivity of the material, and tmeperature. This study shows that diffusion coefficient, D of 12% Cr rotor steel at 953K with 74.8 MPa is 1.084~3.140*$10^{15}mm^2sec^1$ compared to $1.658*10^{24}mm^2sec^1$at 963K without stress. During creep, the growth of martensite laths accelerates the diffusion coefficient under stress due to incoherency of interface between carbides and matrix.

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Prediction of the Diffusion Controlled Boundary Layer Transition with an Adaptive Grid (적응격자계를 이용한 경계층의 확산제어천이 예측)

  • Cho J. R.
    • Journal of computational fluids engineering
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    • v.6 no.4
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    • pp.15-25
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    • 2001
  • Numerical prediction of the diffusion controlled transition in a turbine gas pass is important because it can change the local heat transfer rate over a turbine blade as much as three times. In this study, the gas flow over turbine blade is simplified to the flat plate boundary layer, and an adaptive grid scheme redistributing grid points within the computation domain is proposed with a great emphasis on the construction of the grid control function. The function is sensitized to the second invariant of the mean strain tensor, its spatial gradient, and the interaction of pressure gradient and flow deformation. The transition process is assumed to be described with a κ-ε turbulence model. An elliptic solver is employed to integrate governing equations. Numerical results show that the proposed adaptive grid scheme is very effective in obtaining grid independent numerical solution with a very low grid number. It is expected that present scheme is helpful in predicting actual flow within a turbine to improve computation efficiency.

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Physical Property Models and Single Cells Analysis for Solid Oxide Fuel Cell (고체산화물 연료전지를 위한 물성치 모델 및 단전지 해석)

  • Park, Joon-Guen;Kim, Sun-Young;Bae, Joong-Myeon
    • 한국신재생에너지학회:학술대회논문집
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    • 2009.06a
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    • pp.379-381
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    • 2009
  • The simulation model for metal-supported Solid Oxide Fuel Cell(SOFC) is developed in this study. Open circuit voltage is calculated using Nernst equation and Gibbs free energy is required by thermodynamic. The exchange current densities are compared with experimental results since exchange current density is most effective factor for the activation loss. Liu's study is used for the exchange current density of cathode, BSCF, and Koide's result is applied for the exchange current density of anode, Ni/YSZ. For the ohmic loss, ionic conductivity of YSZ is described from Kilner's mode and the data are compared with Wanzenberg's experimental data. Diffusivity is an important factor for the mass transfer through the porous medium. Both binary diffusion and Knudsen diffusion are considered as the diffusion mechanism. For validation, simulation results at this work are compared with our experimental results.

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Electronic Journal : Replacement or New Paradigm\ulcorner (전자저널 : 점진적인 대체인가, 새로운 패러다임인가\ulcorner)

  • 남수현;설성수;윤배현
    • Journal of Korea Technology Innovation Society
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    • v.1 no.1
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    • pp.83-95
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    • 1998
  • Although an academic journal has had an important role in the diffusion of knowledge and the confirmation of knowledge advancement, it has revealed several difficulties : long processing time for publishing, uni - directional communication, closed review process etc. But an electronic journal (E-Journal) can solve these problems and add several new advantages such as the multimedia expression of documents, and pre and post publication review. Moreover, it should be noted that an E-Journal is not an alternative medium which simply replaces an existing journal, but a new paradigm for scholarly communication. Although this paper reviews several issues related to E-Journal, the introduction of the concept of universal service and informal document style for flexible communication are noticeable. For effective diffusion of E-Journal, information infrastructures such as high - speed telecommunication networks and digital libraries are urgently needed. Government subsidy as in Great Britain is necessary for E-Journal publishing.

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An Automatic Contour Detection of 2-D Echocardiograms Using the Heat Anisotropic Diffusion Method (Heat Anisotropic Diffusion 방법을 이용한 2차원 심초음파도의 경계선 자동검출)

  • Shin, Dong-Jo;Jung, Jung-Wan;Kim, Hyouk;Kim, Dong-Youn
    • Proceedings of the KOSOMBE Conference
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    • v.1994 no.12
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    • pp.9-13
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    • 1994
  • The Heat Anisotropic Diffusion Method has shown very effective for the contour detection of 2-D echocardiogram. To implement this algorithm, we have to choose the parameter C, K, and the threshold level. The choice of C and K are not very sensitive for the good edge detection of the echocardiogram, however the choice of the threshold level is very critical. Until now the threshold level is chosen by the trial and error method. In this paper, we present an automatic threshold decision method from the histogram of the gradient of boundary-like pixels.

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Analytical Deterioration Modelling for Recarbontion of Repaired Concrete (보수된 콘크리트의 재탄산화 열화에 대한 분석적 모델)

  • Do, Jeong-Yun;Kim, Doo-Kie;Song, Hun;Jo, Young-Kug
    • Proceedings of the Korea Concrete Institute Conference
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    • 2010.05a
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    • pp.217-218
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    • 2010
  • This study presented the analytical evaluation model effective in the concrete structure repaired with a patching material. The model considered the effect of the repair material on carbon dioxide penetration into the repaired concrete as evaluating the remaining service life of the CO2-deteriorated concrete structure after repair. The diffusion profiles of carbon dioxide as well as the carbonated concrete were effectively able to be modelled with analytical method based on Fick's 1st diffusion law.

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FAST MATRIX SPLITTING ITERATION METHOD FOR THE LINEAR SYSTEM FROM SPATIAL FRACTIONAL DIFFUSION EQUATIONS

  • LIANG, YUPENG;SHAO, XINHUI
    • Journal of applied mathematics & informatics
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    • v.38 no.5_6
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    • pp.489-506
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    • 2020
  • The spatial fractional diffusion equation can be discretized by employing the implicit finite difference scheme using the shifted Grünwald formula. The discretized linear system is obtained, whose the coefficient matrix has a diagonal-plus-Toeplitz structure. In order to solve the diagonal-plus-Toeplitz linear system, on the basis of circulant and skew-circulant splitting (CSCS splitting), we construct a new and efficient iterative method, called DSCS iterative methods, which have two parameters. Than we prove the convergence of DSCS methods. As a focus, we derive the simple and effective values of two optimal parameters under some restrictions. Some numerical experiments are carried out to illustrate the validity and accuracy of the new methods.

Analysis and Calibration of Transient Enhanced Diffusion for Indium Impurity in Nanoscale Semiconductor Devices

  • Lee Jun-Ha;Lee Hoong-Joo
    • KIEE International Transactions on Electrophysics and Applications
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    • v.5C no.1
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    • pp.18-22
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    • 2005
  • We developed a new systematic calibration procedure and applied it to the calibration of the diffusivity, segregation and TED model of the indium impurity. The TED of the indium impurity was studied under 4 different experimental conditions. Although the indium proved to be susceptible to the TED, the RTA was effective in suppressing the TED effect and in maintaining a steep retrograde profile. Just as in the case of boron, indium demonstrated significant oxidation-enhanced diffusion in silicon and its segregation coefficients at the Si/SiO₂ interface were significantly below 1. In contrast, the segregation coefficient of indium decreased as the temperature increased. The accuracy of the proposed technique has been validated by SIMS data and 0.13-㎛ device characteristics such as Vth and Idsat with errors less than 5% between simulation and experiment.