• Title/Summary/Keyword: diffusion mechanism

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Crystallization of High Purity Ammonium Meta-Tungstate for production of Ultrapure Tungsten Metal

  • Choi, Cheong-Song
    • Proceedings of the Korea Association of Crystal Growth Conference
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    • 1997.10a
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    • pp.1-5
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    • 1997
  • The growth mechanism of AMT(Ammonium Meta-Tungstate) crystal was interpreted as two-step model. The contribution of the diffusion step increased with the increase of temperature, crystal size, and supersaturation. The crystal size distribution from a batch cooling crystallizer was predicted by the numerical solution of a mathematical model which uses the kinetics of nucleation and crystal growth. Temperature control of a batch crystallizer was studied using Learning control algorithm. The purity of AMT crystal producted in this investigation was above 99.99%.

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Transient Simulation of CMOS Breakdown characteristics based on Hydro Dynamic Model (Hydro Dynamic Model을 이용한 CMOS의 파괴특성의 Transient Simulation해석)

  • Choi, Won-Cheol
    • Journal of the Korean Society of Industry Convergence
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    • v.5 no.1
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    • pp.39-43
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    • 2002
  • In present much CMOS devices used in VLSI circuit and Logic circuit. With increasing a number of device in VLSI, the confidence becomes more serious. This paper describe the mechanism of breakdown on CMOS, especially n-MOS, based on Hydro Dynamic model with device self-heating. Additionally, illustrate the CMOS latch-up characteristics on simplified device structure on this paper.

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Studies on the Active Materials of Alkaline Storage Battery(II) Electrochemical Behavior of. Nickel Anode (알칼리 축전지의 활물질에 관한 연구(II)-니켈양극의 전기화학적 거동-)

  • 주충렬;이주성
    • Journal of Surface Science and Engineering
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    • v.15 no.3
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    • pp.146-151
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    • 1982
  • The electrochemical reaction behavior of nickel electrode of the nickel-cadium battery system in potassium hydroxide solution has been studied by cyclic voltammetry, controlled potential electrolysis and X-ray diffraction method. It has been found that the reaction mechanism of positive nickel electrode for charging was assumed to be proten transfer step with a rate controlling diffusion process and char-ging state of positive electrode was amorphous $\beta$-NiOOH.

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Theoretical Overview of Membrane Transport (막물질 이동의 이론적 고찰)

  • Park, Young
    • Membrane Journal
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    • v.3 no.3
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    • pp.94-107
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    • 1993
  • Many researchers have discussed how membrane performance can be enhanced through an understanding of polymer science and engineering. The understandings of transport in porous membrane are used to achieve the isolation of certain components from mixtures. Particular emphasis is placed on the applicability of membrane separations for the isolation of macromolecules[1]. An awareness of membrane structure characteristics is required for the rational design of membranes for specific and/or new applications. This understanding rests on the knowledge of fields such as polymer thermodynamics[2], polymer adsorption [3, 4], diffusion in polymers[5, 6], reaction mechanism[7], and the dynamic behavior[8, 9] of polymer in porous membrane.

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The Grain Growth Mechanism of Sm123 Superconductor in Melt-Textured Growth Method (용융-응고법으로 제조된 Sm123 초전도체의 결정성장 기구)

  • 한상철;성태현;한영희;이준성;김상준
    • Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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    • 2001.02a
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    • pp.9-12
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    • 2001
  • The microstructure evolution and the peritectic solidification of Sm$Ba_{2}$$Cu_{3}$ $O_{7-\delta}$ superconducting materials during the isothermal annealing were studied over the temperature range 1030-$1060^{\circ}C$ The faceted growth of the peritectic phase and its dependence upon Sm-diffusion in the liquid phase are discussed. A growth model is proposed to explain the growth shape of Sm123 crystals.

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Visualization of Combustion by Using Laser Diagnostic Techniques (레이저 진단기법을 이용한 연소 가시화 기술)

  • Chung S. H.;Won S. H.
    • Journal of the Korean Society of Visualization
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    • v.2 no.1
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    • pp.52-56
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    • 2004
  • Several visualization techniques of laser diagnostics are presented for combustion phenomena, including Mie scattering for flow, Rayleigh and Raman scattering spectroscopy for major species, laser-induced fluorescence for minor species, and laser-induced incandescence for soot. These techniques have been applied to understand the various combustion phenomena more clearly, including buoyancy-dominant flow system, diffusion flam oscillation, laminar and turbulent lifted flames, flame propagation along a vortex ring, and soot zone characteristics. The usefulness of laser diagnostics on a better understanding of physical mechanism is demonstrated.

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Comparisons of Reverse Osmosis and Pervaporation Membrane Processes I. Theoretical Interpretations

  • Rhim, Ji-Won;Lee, Kew-Ho;Huang, Y.M.
    • Proceedings of the Membrane Society of Korea Conference
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    • 1991.10a
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    • pp.47-48
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    • 1991
  • The pressure in RO leads to a concentration difference across the membrane, while the concentration difference in PVAP across the membrane is achieved by applying a vacuum to the downstream compartment. Therefore, it could be possible to compare this two processes using the solution-diffusion mechanism.

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NMR PEAK ASSIGNMENT FOR THE ELUCIDATION OF THE SOLUTION STRUCTURE OF T4 ENDONUCLEASE V

  • Im, Hoo-Kang;Jee, Jun-Goo;Yu, Jun-Suk;Lee, Bong-Jin
    • Proceedings of the Korean Biophysical Society Conference
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    • 1996.07a
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    • pp.18-18
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    • 1996
  • Bacteriophage T4 endonuclease V initiates the repair of ultraviolet (UV)-induced pyrimidine dimer photoproducts in duplex DNA. The mechanism of DNA strand cleavage involves four sequential steps: linear diffusion along dsDNA, pyrimidine dimer-specific binding, pyrimidine dimer-DNA glycosylase activity, and AP lyase activity. (omitted)

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Calcium-Dependent Cell Damage Induced by Bile Acid

  • Kim, Joo-Young;Kim, Kyung-Hwan;Lee, Min-Goo
    • Proceedings of the Korean Biophysical Society Conference
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    • 2002.06b
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    • pp.24-24
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    • 2002
  • The mechanism of how cholelithiasis increases the risk of acute pancreatitis remains obscure. When gallstones obstruct the lower biliary tract, bile acids can enter the pancreas either by luminal diffusion or by interstitial leakage. Here we provide the first evidence that bile acids can be transported into pancreatic acinar cells through the membrane transporters and induce cell death by impairing intracellular Ca$\^$2+/ signals.(omitted)

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A One-Step Synthesis and Antimicrobial Activities of New Substituted Dihydro-1,3,4-Thiadiazoles

  • Mahran, Asma M.;Hassan, Nasser A.
    • Archives of Pharmacal Research
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    • v.29 no.1
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    • pp.46-49
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    • 2006
  • In this study, 2-N-arylimino-2,3-dihydro-1,3,4-thiadiazoles derivatives (6a-h) were synthetized. The mechanism of the studied reactions was discussed. The chemical structures of the compounds were elucidated by their IR, $^1H-NMR,\;^{13}C-NMR$, and Mass spectral data and elemental analyses. The compounds were tested for antimicrobial activity using diffusion agar technique.