• 한국전산유체공학회:학술대회논문집
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• 1997.10a
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• pp.99-105
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• 1997

A finite-difference method based on conservative supra characteristic method type upwind flux difference splitting has been developed to study the nonequilibrium chemically reacting inviscid flow. For nonequilibrium air, NS-1 species equations were strongly coupled with flowfield equations through convection and species production terms. Inviscid nonequilibrium chemically reacting air mixture flows over Blunt-body were solved to demonstrate the capability of the current method. At low altitude flight conditions the nonequilibrium air models predicted almost the same temperature, density and pressure behind the shock as equilibrium flow: however, at high altitudes they showed substantial differences due to nonequilibrium chemistry effect. The new nonequilibrium chemically reacting upwind flux difference splitting mettled can be extended to viscous flow and multi-dimensional flow conditions.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.1
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• pp.147-153
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• 2011

A series of nonequilibrium molecular dynamics(NEMD) simulations are performed to investigate the kinetic energy and velocity distributions of molecules in shock waves. In the simulations, argon molecules are used as a medium gas through which shock waves are propagating. The kinetic energy distribution profiles reveals that as a strong shock wave whose Mach number is 27.1 is applied, 39.6% of argon molecules inside the shock wave have larger kinetic energy than molecular ionization energy. This indicates that an application of a strong shock wave to argon gas can give rise to an intense light. The velocity distribution profiles in z direction along which shock waves propagate clearly represent two Maxwell-Boltzmann distributions of molecular velocities in two equilibrium regions and one bimodal velocity distribution profile that is attributed to a nonequilibrium region. The peak appearing in the directional temperature in z direction is discussed on a basis of the bimodal velocity distribution in the nonequilibrium region.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.71-79
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• 1999

Numerical analysis on the characteristics of nitrogen oxides (NOx) formation in turbulent nonpremixed hydrogen-air flames was carried out. Lagrange IEM model and Assumed PDF model were applied to consider turbulence-chemistry interaction known to affect the production of NOx. Partial equilibrium assumption was used to predict nonequilibrium effect to which one-half power dependence between EINOx normalized by flame residence time and global strain rate is attributed. As a result. such one-half power dependence could be reproduced only by reaction model including $HO_{2}$and $H_{2}O_{2}$, which means its dependence on Damkohler number; nonequilibrium effect. This dependence was shown better in the region of higher global strain. Besides, the improvement of turbulence model is required to predict mean flow properties quantitatively in the radial direction.

• Bulletin of the Korean Chemical Society
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• v.26 no.12
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• pp.1986-1990
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• 2005

We study the relaxation kinetics of reversible reactions of the type A + B $^\leftarrow_\rightarrow$ C + B by applying the manyparticle kernel theory, which we have developed to investigate many particle effects on general diffusioninfluenced reactions. It is shown that for the target model, where A and C molecules are immobile and their interconversion is induced by the encounter with the B molecules that are present in much excess, the manyparticle kernel theory gives a result that coincides with the known exact result.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.1
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• pp.156-163
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• 2010

A nonequilibrium molecular dynamics(NEMD) simulation method is developed and applied to study shock waves propagating through argon gas. In this simulation method, shock waves are generated by pushing a piston at a constant speed from one side of a simulation box filled with argon molecules. A linear relationship between piston speeds and shock speeds is observed. Thermodynamic properties including density, temperature, and pressure before and after the shock front are obtained from the simulations and compared with the well-known Rankine-Hugoniot equations based on ideal gases. The comparison shows an excellent agreement, indicating that this NEMD simulation method can be employed to investigate various physical properties of shock waves further.

• Proceedings of the Korean Society of Potoscience Conference
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• spring
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• pp.24-24
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• 1996

• 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.

• Journal of the Korean Society of Combustion
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• v.4 no.2
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• pp.51-62
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• 1999

NOx formation in turbulent flames is strongly coupled with temperature, superequilibrium concentration of O radical, and residence time. This implies that in order to accurately predict NO level, it is necessary to develop sophisticated models able to account for the complex turbulent combustion processes including turbulence/chemistry interaction and radiative heat transfer. The present study numerically investigates the turbulent nonpremixed hydrogen jet flames using the laminar flamelet model. Flamelet library is constructed by solving the modified Peters equations and the turbulent combustion model is extended to nonadiabatic flame by introducing the enthalpy defect. The effects of turbulent fluctuation are taken into account by the presumed joint PDFs for mixture fraction, scalar dissipation rate, and enthalpy defect. The predictive capability of the present model has been validated against the detailed experimental data. Effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.93-104
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• 1999

NOx formation in turbulent flames is strongly coupled with temperature, superequilibrium concentration of O radical, and residence time. This implies that in order to accurately predict NO level, it is necessary to develop sophisticated models able to account for the complex turbulent combustion processes including turbulence/chemistry interaction and radiative heat transfer. The present study numerically investigates the turbulent nonpremixed hydrogen jet flames using the laminar flamelet model. Flamelet library is constructed by solving the modified Peters equations and the turbulent combustion model is extended to nonadiabatic flame by introducing the enthalpy defect. The effects of turbulent fluctuation are taken into account by the presumed joint PDFs for mixture fraction, scalar dissipation rate, and enthalpy defect. The predictive capability of the present model has been validated against the detailed experimental data. Effects of nonequilibrium chemistry and radiative heat loss on the thermal NO formation are discussed in detail.

• Proceedings of the Membrane Society of Korea Conference
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• 2005.11a
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• pp.96-101
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• 2005

A theory for the material transports through ion exchange membrane has been developed on the basis of nonequilibrium thermodynamics by removing the assumption of solvent flow in the previous paper and applied to a detailed study of the ionic transport properties of new charged mosaic membrane(CMM) system. The CMM having two different fixed charges in the polymer membrane indicated unique selective transport behavior then ion-exchange membrane. The separation behavior of ion transport across the CMM with a parallel array of positive and negative functional charges were investigated. It was well-known the analysis of the volume flux and solute flux based on nonequilibrium thermodynamics. Our suggests preferential salt transport across the charged mosaic membranes. Transport properties of heavy metal ions, $Mg^{2+}$, $Mn^{2+}$and sucrose system across the charged mosaic membrane were estimated. As a result, we were known metal salts transport depended largely on the CMM. The reflection coefficient indicated the negative value that suggested preferential material transport and was independent of charged mosaic membrane thickness.