• 한국공작기계학회논문집
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• 제10권1호
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• pp.112-119
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• 2001

Design sensitivity is an important is an important device in improving a mechanical system design. A continuum design consists of the shape and orientation design. This research develops the shape and orientation design sensitivity method. The configura-tion design variables of multibody systems define the shape and orientation changes. The equations of motion are directly differentiated to obtain the governing equations for the design sensitivity. The governing equation of the design sensitivity is formulated as an over determined differential algebraic equation and treated as ordinary differential equations on mani-folds. The material derivative of a domain functional is performed to obtain the sensitivity due to shape and orientation changes. The configuration design sensitivities of a fly-ball governor system and a spatial four bar mechanism are obtained using the proposed method and are validated against those obtained from the finite difference method.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2003년도 봄 학술발표회 논문집
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• pp.235-242
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• 2003

The solids and the fluids in porous media have a relative velocity to each other. Due to physically and chemically different material properties and their relative velocity, the behavior of saturated porous media is extremely complicated. Thus, in order to describe and clarify the deformation behavior of saturated porous media, constitutive models for deformation of porous media coupling several effects such as flow of the fluids or thermodynanical change need to be developed in frame of Arbitrary Lagrangian Eulerian (ALE) description. The aim of ALE formulations is to maximize the advantages of Lagrangian and Eulerian elements, and to minimize the disadvantages. Therefore, this method is appropriate for the analysis of porous media that are considered for the behavior of the solids and the fluids. In this work, governing equations of porous media based on ALE description are obtained from governing equations in frame of updated Lagrangian description. Then, weak forms of these equations are derived using arbitrary weighting functions.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.940-952
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• 2007

It is found that there are many serious errors in deriving the existing governing equations of motion for a wheel-axle set negotiating an arbitrarily changing radius curve by Vijay K. Garg and Rao V. Dukkipati. Among other things, despite the hypothesis on arbitrarily changing radius of curve, there had been no taking a time derivative of the radius R in the first half of the derivation. Even if the D'lambert force arising from the centrifugal acceleration of vehicle body or bogie was appropriately taken into account while calculating cant deficiency, it is unnecessarily duplicated in the force vectors of governing equations. The graphical model given in Fig. 5.15 is not enough to follow those developed expressions from both physical and structural points of view. Besides, there are some blunders in assigning plus or minus sign not to be regarded as simple typographic ones and similar mistakes are committed in deriving creep force expressions as in the case of a wheel-axle set on a tangent track.

• 대한기계학회논문집A
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• 제25권7호
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• pp.1119-1124
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• 2001

Nonlinear Vibration of a flexible circular ring is studied in this paper. Based upon the von Karman strain theory, the nonlinear governing equations are derived, in which the in-plane bending and extension displacements as well as the out-of-plane bending displacement are fully coupled. After discretizing the governing equations by the Galerkin approximation method, we obtain the linearlized equation by using the pertubation method. The results from the linearlized equations show that the in-plane displacement has effects on the natural frequencies of the out-of-plane displacement.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.117-122
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• 1998

A numerical study is carried out to investigate the transient process of combustion phenomena associated with hypersonic propulsion devices. Reynolds averaged Navier-Stokes equations for reactive flows are used as governing equations with a detailed chemistry mechanism of hydrogen-air mixture and two-equation SST turbulence modeling. The governing equations are discretized by a high order accurate upwind scheme and solved in a fully coupled manner with a fully implicit time accurate method. At first, oscillating shock-induced combustion is analyzed and the comparison with experimental result gives the validity of present computational modeling. Secondly, the model ram accelerator experiment was simulated and the results show the detailed transient combustion mechanisms. Thirdly, the evolution of oblique detonation wave is simulated and the result shows transient and final steady state behavior at off-stability condition. Finally, shock wave/boundary layer interaction in combustible mixture is studied and the criterion of boundary layer flame and oblique detonation wave is identified.

• 대한토목학회논문집
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• 제9권3호
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• pp.13-19
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• 1989

박판으로 이루어진 아치가 양단에서 휨모멘트를 받을 때 발생하는 횡좌굴에 대한 지배 미분방정식이 제시되었다. 미분방정식은 updated Lagrangian 방법에 따른 증분형태의 가상일의 원리에 의하여 유도 되었다. 본 연구에서 구한 임계모멘트 값들을 다른 결과들과 비교함으로써 본 연구의 타당성을 검토하여 보았다.

• 해양환경안전학회지
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• 제4권2호
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• pp.63-68
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• 1998

This study is aimed to predict the configuration and tension of a towing cable of a side-scan sonar which plays an important role in developing ocean resources. The governing equations of 3-D static equilibrium equations for a flexible cable are derived and solved using a finite difference method. The forces considered in this paper are effective weights, drag forces due to currents and ship moving, and the tension at both ends of the towing cable. The governing equations are non-linear, so an iteration method is applied to solve the equation. A case study is carried out for several different conditions. The result will be useful for predicting the location of a side-scan sonar and to design the towing system.

• Advances in materials Research
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• 제4권1호
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• pp.31-44
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• 2015

This paper presents a simple n-order four variable refined theory for buckling analysis of functionally graded plates. By dividing the transverse displacement into bending and shear parts, the number of unknowns and governing equations of the present theory is reduced, and hence, makes it simple to use. The present theory is variationally consistent, uses the n-order polynomial term to represent the displacement field, does not require shear correction factor, and eliminates the shear stresses at the top and bottom surfaces. A power law distribution is used to describe the variation of volume fraction of material compositions. Equilibrium and stability equations are derived based on the present n-order refined theory. The non-linear governing equations are solved for plates subjected to simply supported boundary conditions. The thermal loads are assumed to be uniform, linear and non-linear distribution through-the-thickness. The effects of aspect and thickness ratios, gradient index, on the critical buckling are all discussed.

• 한국수자원학회논문집
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• 제44권6호
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• pp.471-476
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• 2011

In this study, a modified dispersion-correction scheme describing tsunami propagation on variable water depths is proposed by introducing additional terms to the previous numerical scheme. The governing equations used in previous tsunami propagation models are slightly modified to consider the effects of a bottom slope. The numerical dispersion of the proposed model replaces the physical dispersion of the governing equations. Then, the modified scheme is employed to simulate tsunami propagation on variable water depths and numerical results are compared with those of the previous tsunami propagation model.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.221-226
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• 1999

Three-dimensional flow analysis and numerical optimization methods are presented for the design of an axial-flow fan. Steady, Incompressible, three-dimensional Reynolds-averaged Wavier-Stokes equations are used as governing equations, and standard k-$\epsilon$ turbulence model is chosen as a turbulence model. Governing equations are discretized using finite volume method. Steepest descent method, conjugate gradient method and BFGS method are compared to determine the searching directions. Golden section method and quadratic fit-sectioning method are tested for one dimensional search. Objective function is defined as a ratio of generation rate of the turbulent kinetic energy to pressure head. Sweep angle distributions are used as design variables.