• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.78-83
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• 1998

A finite-difference method based on conservative supra characteristic method(CSCM) type upwind flux difference splitting has been studied on the bluntness effect on the wall heat transfer rate and wall pressure over blunt-body. The results show that the stagnation heating varies inversely with the square root of the nose radius.

• Tribology and Lubricants
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• 제22권1호
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• pp.33-39
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• 2006

During the high speed train operation in the conventional line, it was found to have extremely severe flange wear, due to the curvy routes. This paper looks at the actions that have been taken to bring the wear to an acceptable level. In particular, it have been presented for flange wear variation depending on curve radius, cant, transition curve length by using numerical method. And the impacts on the flange wear by the application of stick type solid lubricant are also presented.

• Journal of applied mathematics & informatics
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• 제24권1_2호
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• pp.367-376
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• 2007

In this paper we consider the global convergence of a new super memory gradient method for unconstrained optimization problems. New trust region radius is proposed to make the new method converge stably and averagely, and it will be suitable to solve large scale minimization problems. Some global convergence results are obtained under some mild conditions. Numerical results show that this new method is effective and stable in practical computation.

• 소음진동
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• 제5권1호
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• pp.85-93
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• 1995

The vibration of the dehydration process in a washing machine is important problem that affects the performance of products. In this paper, the upper structure of a washing machine is modeled as rigid body suspension system and, by numerical analysis, the amplitude of a spin basket and the transfer moment at a base plate are calculated. To examine the vibrational characteristics according to design variable change, the friction coefficient in anubber, the radius of curvature, the stiffness coefficient, initial length and locations of support springs are considered in the analysis. Experimental results are compared with those of analysis.

• 천문학회지
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• 제34권4호
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• pp.265-269
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• 2001

We present preliminary numerical simulations of tilted-disk accretion around a rotating black hole. Our goal is to explore whether hydrodynamic instabilities near the Bardeen-Petterson radius could be responsible for generating moderate-frequency quasi-periodic oscillations in X-ray binaries. We review the relevant general relativistic hydrodynamic equations, and discuss preliminary results on the structure and dynamics of a thin, Keplerian disk.

• Steel and Composite Structures
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• 제34권1호
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• pp.141-154
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• 2020

In the present paper, free vibration analysis of angle-ply laminated composite annular and circular plates is performed by numerical methods. First-order shear deformation plate theory is used for kinematic relations. The related governing equations of motion are discretized via differential quadrature and discrete singular convolution methods. Frequency values are obtained for different lamina scheme, thickness-to-radius ratio, and mode numbers. The advantages and accuracy of these two methods are also tested in detail.

• Nuclear Engineering and Technology
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• 제34권4호
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• pp.314-322
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• 2002

A new extrapolation method is developed and applied to the additive angular dependent rebalance (AADR) acceleration for discrete ordinates neutron transport calculations. With this extrapolation, the convergence of AADR solution for distinct discretizations between the high- order and low-order equations is remarkably improved and thus the “inconsistent discretization problem” is resolved. Fourier analysis is also performed to find the optimal extrapolation and weighting parameters, which give the smallest spectral radius. The numerical tests demonstrate that the AADR with extrapolation works well as predicted by the Fourier analysis.

• 대한기계학회논문집B
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• 제39권6호
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• pp.497-504
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• 2015

본 논문에서는 박테리아 편모를 모사한 스프링 모델을 이용하여 박테리아의 편모의 추진적 거동에 관한 연구를 수행하였다. 본 해석에서는 상용프로그램을 사용하였으며, 별도의 회전영역 설정에 따른 수치기법의 타당성 확인과 더불어 파라미터 연구를 수행하였다. 수치해석 결과는 전반적으로 Resistive force theory와는 잘 일치하지 않았지만, Slender body theory와는 잘 일치하였다. 그리고 스프링의 회전속도, 피치, 나선반경 및 유체의 점성의 영향을 확인하였다. 또한 벽과의 거리에 따른 효과도 분석하였다.

• 대한조선학회논문집
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• 제48권2호
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• pp.141-146
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• 2011

This study numerically carried out the propeller open water test(POW) by solving Navier-Stokes equations governing the three-dimensional unsteady incompressible viscous flow with the turbulence closure model of the ${\kappa}-{\omega}$ SST model. Numerical simulations are performed at various range of advance ratios. Corresponding to Reynolds numbers of $5.89{\times}105{\sim}6.47{\times}105$ based on free stream velocity and the chord length at 0.7 propeller radius. The present results give a good agreement with those of the experiment. The propeller induced vortical structures have been analyzed by visualizing the resultant vorticity. As the advance ratio increases, the magnitude and length of the resultant vorticity decrease significantly. As the main focus of present study, the numerical model to present the ($r-{\theta}$) plane-averaged resultant vorticity along the streamwise direction for various advance ratios has been suggested.

• Geomechanics and Engineering
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• 제18권3호
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• pp.225-234
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• 2019

A numerical stepwise approach for cavity expansion problem in strain-softening rock or soil mass is investigated, which is compatible with Mohr-Coulomb and generalized Hoek-Brown failure criteria. Based on finite difference method, plastic region is divided into a finite number of concentric rings whose thicknesses are determined internally to satisfy the equilibrium and compatibility equations, the material parameters of the rock or soil mass are assumed to be the same in each ring. For the strain-softening behavior, the strength parameters are assumed to be a linear function of deviatoric plastic strain (${\gamma}p^*$) for each ring. Increments of stress and strain for each ring are calculated with the finite difference method. Assumptions of large-strain for soil mass and small-strain for rock mass are adopted, respectively. A new numerical stepwise approach for limited pressure and plastic radius are obtained. Comparisons are conducted to validate the correctness of the proposed approach with Vesic's solution (1972). The results show that the perfectly elasto-plastic model may underestimate the displacement and stresses in cavity expansion than strain-softening coefficient considered. The results of limit expansion pressure based on the generalised H-B failure criterion are less than those obtained based on the M-C failure criterion.