• International Journal of Aeronautical and Space Sciences
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• v.9 no.2
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• pp.34-40
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• 2008

The aeroelastic analyses for several wing models were performed using the transonic small-disturbance (TSD) equation, which is very efficient, to consider the aerodynamic nonlinearities in the transonic region. For more accurate aerodynamic analysis of airfoil and wing models with shock waves, the viscous equations based on the Green's lag-entrainment equation of boundary-layer effects were coupled with the TSD equation in the transonic region. Finally the aeroelastic characteristics of wing models were investigated through comparisons of the aeroelastic analysis results for wing models considering the change of a thickness of the airfoil section. Moreover, the results of the aeroelastic analysis using the coupled TSD equation with the viscous equations were compared with those using the TSD equation for several wing models.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.16 no.2
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• pp.125-135
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• 2012

The transient magnetohydrodynamic (MHD) generalized Couette flow with heat transfer through a porous medium of an electrically conducting, viscous, incompressible fluid bounded by two parallel insulating porous plates is studied in the presence of uniform suction and injection and a heat source considering the Hall effect. A uniform and constant pressure gradient is imposed in the axial direction and an externally applied uniform magnetic field as well as a uniform suction and injection are applied in the direction perpendicular to the plates. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the Hall current, the porosity of the medium and the uniform suction and injection on both the velocity and temperature distributions is investigated.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.20 no.4
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• pp.309-332
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• 2016

Finite element method has been applied to solve the fundamental governing equations of natural convective, electrically conducting, incompressible fluid flow past an infinite vertical plate surrounded by porous medium in presence of thermal radiation, viscous dissipation, Soret and Dufour effects. In this research work, the results of coupled partial differential equations are found numerically by applying finite element technique. The sway of significant parameters such as Soret number, Dufour number, Grashof number for heat and mass transfer, Magnetic field parameter, Thermal radiation parameter, Permeability parameter on velocity, temperature and concentration evaluations in the boundary layer region are examined in detail and the results are shown in graphically. Furthermore, the effect of these parameters on local skin friction coefficient, local Nusselt number and Sherwood numbers is also investigated. A very good agreement is noticed between the present results and previous published works in some limiting cases.

• Journal of The Korean Astronomical Society
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• v.34 no.4
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• pp.251-254
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• 2001

To examine the structure and dynamics of thick accretion disks, we use a two-dimensional viscous hydrodynamic code coupled with radiation transport. The $\alpha$-model and the full viscous stress-tensor description for the kinematic viscosity are used. The radiation transport is treated in the gray, flux-limited diffusion approximation. The finite difference methods used are based on an explicit-implicit method. We apply the numerical code to the Super-Eddington black-hole model for SS 433.@The result for a very small viscosity parameter a reproduces well the characteristic features of SS 433, such as the relativistic jets with $\~$0.26c, the small collimation degree of the jets, the mass-outflow rate of ${\ge}5{\times}10^{-7}M{\bigodot}yr^{-1}$, and the formation of the X-ray iron emission lines.

• Journal of the Korean Ceramic Society
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• v.25 no.1
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• pp.49-53
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• 1988

Polycarbosilane was synthesized from the pyrolysis of polydimethylsilane, which is dechlorinated from dimethyldichlorosilane. The pyrolysis temperature was varied at 280-480$^{\circ}C$ for 2 hours. FT-IR, FT-NMR and GPC measurement were studied on the residue inside the reaction crucible and viscous solution inside the cooling zone respectively. From the viscous solution in the cooling zone at 420$^{\circ}C$, the synthesis of polycarbosilane wa well detected.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.57-62
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• 2005

STX shipbuilding Co,. Ltd. has been developed a hull form and propeller of medium class container vessel. The present paper deals with numerical calculations and experimental tests for the investigation of wave resistance, viscous resistance and propeller. The characteristics of wave resistance and self propulsion factors are varied in order to find an optimized hull form. The measured results have been compared with computed results by 'WAVIS' The prediction of the caviation occurrence was predicted by 'Opti-pro' and measurement is performed in KRISO.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.564-571
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• 2007

In the present study, stern form optimization has been carried out using computational fluid dynamics (CFD) techniques. The viscous pressure drag has been minimized to optimize stern shape. Parametric modification function has been used to modify the shape of the hull. By the use of the parametric modification function and algebraic scheme to grid manipulation, the initial ship geometry was easily deformed according to change of design parameters. For purpose of illustration, KRISO 319K VLCC (KVLCC) is chosen for example ship to demonstrate stern form optimization. The numerical results indicate that the optimized hull yields a reduction in viscous resistance.

• Elastomers and Composites
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• v.26 no.4
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• pp.296-303
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• 1991

Surface of crystalline silica was sequentially reacted with silane(A 187), liquid $rubber(CTBN{\times}8)$, and vinyl monomer(GMA) in existence of TEA(triethylamine) or BPO(benzoyl peroxide). It was mixed with epoxy resin at a ratio $0{\times}60%$ (vol. % ) of total component. For mixtures, viscous properties were investigated experimentally. 1) Coating ratio depended on pH of mixture and quantity of catalyst. 2) Treated silica represented lower viscosity than untreated. 3) Thixotropic index represented best at silica_content $15{\sim}23%$ and showed more large deviation over $120^{\circ}C$. 4) Relative viscosity followed kernel's at $0{\times}10%$ of silica content and get out of Mooney's at more than 15%.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.9
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• pp.799-807
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• 2005

The flow characteristics and the heat transfer rate on a surface by the interaction of a pair of vortices are studied numerically. To analyze the common flow up produced by vortex generators in a rectangular channel flow, the pseudo-compressibility viscous method is introduced into the Reynolds-averaged Navier-Stokes equation for 3-dimensional unsteady, incompressible viscous flows. To predict turbulence characteristics, a two-layer $k-\varepsilon$ turbulence model is used on the flat plate 3-dimensional turbulence boundary The computational results predict accurately Reynolds stress, turbulent kinetic energy and flow field generated by the vortex generators. The numerical results, such as thermal boundary layers, skin friction characteristics and heat transfers, are also reasonably close to the experimental data.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.10
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• pp.1025-1033
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• 2001

A scaling analysis is provided which predicts the sliding velocity of a liquid drop down an inclined surface. The analysis is based on the balance of the gravitational work rate that drives the drop sliding and the resistances by capillary and viscous forces. The capillary resistance is accounted for via the contact angle hysteresis, which is quantified by measuring the critical inclination causing the drop to start sliding. The sliding of the drop is governed by the rate of the viscous dissipation of the Stokes flow. The analysis result in its limit form for small contact angles is consistent with previous results. In the experiments to verify the analysis results, the measured sliding velocity of various liquid drops are shown to obey the predictions made in this study.