• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.72-77
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• 2001

고층 빌딩의 풍하중에 의한 진동을 제어하기 위하여 MR 유체감쇠기를 이용한 반능동 제어 시스템의 설계에 대하여 연구하였다. 제안된 설계기법의 효율성을 검증하기 위하여 ASCE benchmark 구조물을 대상으로 수치 모의 해석을 수행하였다. 유전자 알고리즘을 사용하여 MR 감쇠기의 76층 빌딩 내에서의 최적위치와 용량을 결정하였으며, clipped optimal control 제어기법을 사용하여 가속도 되먹임 구조를 갖는 MR 감쇠기의 제어 알고리즘을 구성하였다, 수치 모의 해석 결과로부터 MR 감쇠기는 ATMD와 유상한 제어 성능을 가지고 있으며 매우 작은 규모의 파워 시스템만으로 운영이 가능한 효율적이고 안정적인 제어 시스템임을 확인할 수 있었다.

• 한국전산유체공학회:학술대회논문집
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• 1996.05a
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• pp.27-32
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• 1996

A previously developed pressure based calculation procedure for incompressible flows was modified and applied to transonic and supersonic flows. It uses pressure as a primary variable in preference to density and body fitted coordinate and non-staggered grid system. The discretized momentum equations were rearranged as a system of equations with respect to covariant velocity components. Three different discretization schemes, QUICK hybrid and first order upwind, were used to approximate the convective terms and compared. Present approach was tested far two transonic flow and one supersonic flow problems. Comparison with previous results show that present approach can be used as a solver for compressible flows.

• Journal of computational fluids engineering
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• v.3 no.2
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• pp.52-64
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• 1998

Numerical simulations on the flowfield of lifting chamber for Wing-In-Ground vehicle were performed using Fluent/UNS 4.2 software. The trend of lifting force in lifting chamber and parametric study of geometric and fluid variables were primarily investigated. Selected parameters for investigation are inlet velocity, height between chamber and water level, depth of the skirt, location of inlet, variaton of height at bow and stern. Also, air capturing capabilities from downstream of the propeller were evaluated at the air inlet. The lifting force was increased linearly with the increased of inlet velocity and nonlinearly with the decrease of height force was increased with increased depth. It turned out to have very minor effect on lifting force to change the location of air inlet for lifting chamber, installed on top surface. Tilting the vehicle when it was lifted, the lifting forces, generated in each case, showed no appreciable changes.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.156-160
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• 2011

As building becomes larger, taller and more complex due to industrialization and urbanization, it tends to be vulnerable to fire and establishment of effective measures for fire safety is demanded. Especially the fact that the smoke hinders evacuation and fire-fighting activities as well as becomes the major cause of life casualty emphasizes the importance of smoke control system. To design and operate the smoke control system success folly, it is necessary to analyze and predict precisely the thermoflow induced by fire in building. The unsteady three-dimensional analysis of thermoflow induced by fire with diverse variables such as building structure, fire conditions and smoke control facilities can be effectively carried out with numerical method In this study, using the FDS(Fire Dynamics Simulation) program that spreads widely as the analysis tool for thermoflow of fire, the analysis of thermoflow in partition of building induced by fire and comparison with the experimental results for assessment of numerical analysis are presented.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.2-5
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• 2011

This paper presents a numerical study on multiphase flows induced by wall adhesion The CSF(Continuum Surface Force} model is used for the calculation of the surface tension force and implemented in an in-house solution code(PowerCFD). The present method(code) employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with volume capturing method(CICSAM) in a volume of fluid(VOF) scheme for phase interface capturing As an application of the present method, the effects of wall adhesion are numerically simulated with the CSF model for a shallow pool of water located at the bottom of a cylindrical tank. Two different cases are computed, one in which the water wets the wall and one in which the water does not wet the wall. It is found that the present method simulates efficiently and accurately surface tension-dominant multiphase flows induced by wall adhesion.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.535-542
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• 2011

To utilizing CFX V12.0.l, internal flow characteristics of denture high-speed air turbine hand-piece unit was identified, in order to analyze the performance of the torque values were compared. In order to find out the difference of torque by mash values, under steady condition, performed grid convergence test. It compared theoretical torque with torque through flow analysis. To describe the motion of turbine blade was used to immerged solid method. Depending on the location of the turbine blade were calculated from five case. Maximum and minimum values of turbine blades was analyzed. To analyze the performance of the torque values were compared with speed of turbine blade.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.572-575
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• 2008

Two-dimensional multiphase flows due to density difference such as the Rayleigh-Taylor instability problem and the droplet splash are simulated by an in-house solution code(PowerCFD). This code employs an unstructured cell-centered method based on a conservative pressure-based finite-volume method with interface capturing method in a volume of fluid(VOF) scheme for phase interface capturing. The present results are compared with other numerical solutions found in the literature. It is found that the present code simulates complex free surface flows such as multiphase flows due to density difference efficiently and accurately.

• Journal of computational fluids engineering
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• v.8 no.1
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• pp.23-29
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• 2003

Two nonlinear κ-ε models with the wall function method are applied to the fully developed turbulent flow in a square duct. Typical predicted quantities such as axial and secondary velocities, turbulent kinetic energy and Reynolds stresses are compared in details both qualitatively and quantitatively with each other. A nonlinear κ-ε model with the wall function method capable of predicting accurately duct flows involving turbulence-driven secondary motion is presented in the present paper. The nonlinear κ-ε model of Shih et al.[1] adopted in a commercial code is found to be unable to predict accurately duct flows with the prediction level of secondary flows one order less than that of the experiment.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.9
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• pp.1327-1334
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• 2003

Flow characteristics of the fluid laden with many particles in the two-dimensional channel are investigated using the Navier-Stokes equations coupled with the equation of motion of particles by direct numerical simulation. A four-step fractional step method with Crank-Nicolson scheme and ALE technique is used for P2P1 mixed finite element method. The motion and distribution of particles in the fluid is virtually described as a result of direct numerical simulation and the increase of viscosity is compared with theoretical equations. The effect of channel height on the relative viscosity and the tubular pinch effect are discussed.

• The KSFM Journal of Fluid Machinery
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• v.13 no.6
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• pp.13-18
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• 2010

The programs of grid generation and flow analysis for the 3-D flow field. were developed. The finer results from numerical analysis could be obtained by using developed programs than those of the experimental data in the flow field of the circular nozzle exit region. Especially A virtual-origin of 3.2 times of nozzle diameter within three percent error inside from nozzle exit plane could be obtained.