• 제목/요약/키워드: nonequilibrium

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Transport Coefficients Across A Charged Mosaic Membrane III

  • Lee, Jungwoon;Minho Kang;Song, Myung-Kwan;Wongkang Yang;Lee, Jang-Woo
    • Korean Membrane Journal
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    • v.5 no.1
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    • pp.61-67
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    • 2003
  • Various characteristics of ion transport properties of a charged mosaic membrane with a parallel array of positive and negative functional charges were investigated, From the analysis of the volume flux, it was found that the salt flux based on nonequilibrium thermodynamics, preferential salt transport across the charged mosaic membrane. Transport properties of the magnesium sulfate(MgSO$_4$) and sucrose across the charged mosaic membrane were estimated. As a result, metal salts transport depended largely on the charged states and molecular weight otherwise nonelectrolyte solution was rejected under all experimental conditions. On the other hand, the reflection coefficient s indicated the negative value that suggested preferential material transport and was independent of charged mosaic thickness.

Prediction of NOx Formation Characteristics in Turbulent Nonpremixed Hydrogen-Air Jet Flames (비예혼합 수소-공기 난류제트화염내의 NOx 생성특성 예측)

  • Kim, S.K.;Kim, Y.M.;Ahn, K.Y.;Oh, K.S.
    • 한국연소학회:학술대회논문집
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    • 1998.10a
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    • pp.165-170
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    • 1998
  • Turbulent nonpremixed $H_2$-air jet flames are numerically investigated using the joint PDF model. The reaction progress variable is derived by assuming the radicals 0, H, and OH to be in partial equilibrium and additional species $HO_2$ and $H_2O_2$ in steady state. The model is extended to npnadiabatic flame by introducing additional variable for the transport of enthalpy and radiative source term is calculated using a local, geometry independent model. In terms of flame structure and NO formation, the predicted results are favorably agreed with experimental data. The effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

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Study on Fluid Flow and Thermal Characteristics in a Nanoscale Channel Using MD Simulation (분자 동역학 시뮬레이션을 이용한 나노 스케일 채널 내에서의 유체 유동 및 열적 특성에 관한 연구)

  • Choi, Yong-Seok;Kim, Sung-Jin
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1880-1884
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    • 2004
  • To analyze the fluid flow and thermal characteristics in a nanoscale system, the planar Poiseuille flow of a Lennar-Jones liquid through parallel plates formed by fixed atoms is studied using nonequilibrium molecular dynamics simulations. The role of important simulation parameters such as the channel width, the magnitude of external field, the temperatures of the top and bottom plates, and the interaction potential parameter between fluid and wall atoms, which affect flow patterns and heat transfer rate inside the channel, are investigated. Under the various simulation conditions, interesting phenomena deviated from the continuum predictions have found.

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The efficiency of subtraction technique in a nonequilibrium molecular dynamics simulation of a simple liquid shear flow (단순액체의 층밀리기 흐름에 대한 비평형 분자동력학 계산에서 공제방법의 효과)

  • 안성청
    • Journal of the Korea Society for Simulation
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    • v.6 no.1
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    • pp.53-60
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    • 1997
  • Results from a nonequilibrium molecular dynamics (NEMD) simulation are presented for an argon liquid subject to a shear flow. The segmented molecular dynamics method and the subtraction technique used in NEMD program to reduce the thermal fluctuation noise in data are studied with different shear rates. The standard deviation in the shear stress reduced from 0.030 to 0.004 by the segmented molecular dynamics method for 50 repeated segments. On the other hand, the standard deviation of the data remained the same when the subtraction technique was applied, where as the results of shear stress by constant value in a random way.

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A Study on Remediation Characteristics of Soils Contaminated with Co using Solvent Flushing Method (Solvent Flushing방법을 이용한 코발트로 오염된 토양의 제염특성에 관한 연구)

  • 김계남;원휘준;김희연;이병직;오원진
    • Journal of Korea Soil Environment Society
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    • v.4 no.2
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    • pp.55-62
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    • 1999
  • The solvent flushing apparatus for soil remediation was designed. After the soil around nuclear facilities was sampled and compulsorily contaminated by Co, the characteristics remediated by solvent flushing were analyzed. Meanwhile, the nonequilibrium sorption code was developed for modelling of the soil remediation by solvent flushing, input parameters needed for modelling were measured by laboratory experiment. Experimental results are as follows : The soil around nuclear facilities belongs to Silt Loam including a lot of silt and sand. When water was used as a solvent, the higher was the hydraulic conductivity. the higher the efficiency of soil remediation was. The values calculated by the nonequilibrium sorption code agreed with experimental values more exactly than the values calculated by the equilibrium sorption code. When EDTA solution was used as a solvent. the soil remediation efficiency by EDTA solution showed higher than that by water.

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Effect of Nonequilibrium Condensation on the Oscillation of the Terminating Shock in a Transonic Airfoil Flow (천음속 익형 유동에 있어서 비평형 응축이 충격파 진동에 미치는 영향)

  • Kim, Jin-Soo;Lee, Sung-Jin;Alam, Miah Md. Ashraful;Kwon, Soon-Bum
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.1
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    • pp.61-66
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    • 2012
  • In this study, to find the effect of nonequilibrium condensation on the oscillation of the terminating shock wave in transonic flows, an NACA0014 airfoil flow with nonequilibrium condensation is analyzed using the total variation diminishing (TVD) numerical scheme. Transonic free stream Mach numbers of 0.81-0.87 are tested with variations in the stagnation relative humidity. For the same free stream Mach number and attack angle of ${\alpha}=0^{\circ}$, an increase in the stagnation relative humidity attenuates the strength of the terminating shock and reduces the oscillation of the terminating shock wave. Furthermore, for the same stagnation relative humidity, the larger the free stream Mach number becomes, the shorter the period of the oscillation shock wave is. The excursion distance of the oscillation shock increases with the free stream Mach numbers for the same stagnation relative humidity. Finally, it is found that for the same shock location, the strength of the oscillating shock facing upstream is stronger than that facing downstream.

The Kinetics of Montmorillonite Expansion in the Treatment with Hexadecyltrimethylammonium (HDTMA와 반응하는 몬모릴로나이트의 팽창 속도론)

  • Lee Seung Yeop;Cho Won Jin
    • Journal of the Mineralogical Society of Korea
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    • v.17 no.4
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    • pp.299-307
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    • 2004
  • Surfactant adsorption by two montmorillonite types with different interlayer cations of Ca and Na was characterized by examining the time dependence of surfactant behavior on the clay surfaces. Surfactants with different micelle concentration were conducted in our experiment to observe a nonequilibrium activity of cationic surfactant on the clay over reaction periods ranging from 0.1 min to 11 days. As compared with Ca-montmorillonite (SAz), a more active intrusion of surfactant molecules into the interlayers was found in Na-montmorillonite (SWy). During a short 'initiation' stage, the basal spacing of SWy montmorillonite increased rapidly with logarithmic time. For SAz montmorillonite, however, the abrupt basal spacing increase occurred at the later stage of the reaction. From the result, the difference in the adsorption behavior exhibited by the two montmorillonite types partly results from their intrinsic nature, that is, inorganic cations originally existing on the clay surfaces. Additionally, the micelle concentration of surfactants affects the development of organo-montmorillonite, especially, in the intercalant formation and stabilization under nonequilibrium.