• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.3 s.174
• /
• pp.645-652
• /
• 2000

A method for shape design sensitivity analysis is proposed utilizing commercial software ANSYS for thermal conduction problems. While the sensitivity formula is derived analytically by introduing adjoint variable concept, sensitivity calculation in practice as well as the primal and adjoint solution of thermal conduction is performed using the ANSYS very easily. Since the formula always takes boundary integral form, sensitivity evaluation in ANSYS requires a little more addition of post-processing routine which involves evaluation of boundary variable from the obtained solution. Though the BEM has been used as a better tool for this purpose, the present study shows it can also be calculated using any kind of analysis code such as ANSYS since the formula is based on analytic nature. Therefore the present study provides a new and efficient way of optimization which was not possible before using commercial software. The usefulness of the method is illustrated via a weight minimization problem of thermal diffuser.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.796-801
• /
• 2002

The goal of this research is the shape design of the valve using a computer simulation. For an analysis a basic mathematical model describing compression cycle is considered as consisting of five sets of coupled equations. These are the volume equation (kinematics), valve dynamic equation (dynamics), ideal gas equation (thermodynamics), Bernoulli equation (fluid dynamics), and dynamic equation of fluid particle based on Helmholtz equation (acoustics). Valve motion is made by the superposition of free vibration modes obtained by the finite element method. That is, the eigenvalues and eigenvectors are the sufficient modeling factors fur the valve in the simulation program. Thus, to design a shape of the valve, shape design sensitivity through chain-ruled derivatives is considered from two sensitivity coefficients, one is the design sensitivity of the capability of compressor with respect to the eigenvalues of the valve, and the other is the design sensitivity of the eigenvalue with respect to the shape change of the valve. In this research, the continuum design sensitivity analysis concepts are used for the latter.

• Journal of Mechanical Science and Technology
• /
• v.17 no.5
• /
• pp.679-690
• /
• 2003

As the rate of increase in areal density of the HDD has accelerated, dynamic characteristics of the HDD actuator need to be improved with respect to the performance of the tracking servo and shock transmission. Therefore, it is important to analyze the vibration characteristic of the HDD actuator that consists of the VCM part, E-block and pivot bearing. In this paper, vibration modes of the HDD actuator are investigated the using finite element and experimental modal analyses methods. To develop a detailed finite element model, finite element models of each components of the actuator assembly are constructed and tuned to the results of the EMA. The VCM coil is modeled as an equivalent finite element model that has an orthotropic material property using auto-model updating program. Auto-model updating program with improved sensitivity based iterative method is applied to build a detailed finite element model using the result of the EMA. A detailed finite element model of the HDD actuator is then constructed and analyzed.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.13 no.1
• /
• pp.1-9
• /
• 1988

The purpose of this paper is study the sensitivity analysis of matrix game. Teh sensitivity analysis of matrix is classified into two types. Type one is to find the characteristic region of an element of the pay off matrix in which the value of the current optimal strategy remains as an optimum. Type two is to find that in which the basis of the current optimal strategy does not change. This paper shows the characteristic regions of basic and nonbasic strategies. Further it is found that the characteristic regions of type one and two are same in the case that the element is that of at least one player's nonbasic strategy.

• Journal of KSNVE
• /
• v.5 no.3
• /
• pp.395-402
• /
• 1995

In general low frequency vibration characteristics like an idleshake is mainly influeced by pillar section properties and joints. So the design technique development of vehicle pillar structures is required to initial design and vehicle development stage. In this paper to develop pillar structure design technique considering low frequency vibration characteristics, strain energy method, design sensitivity analysis method, and design optimization method using commercial finite element analysis program and optimization program are presented.

• Journal of the Korean Professional Engineers Association
• /
• v.28 no.2
• /
• pp.90-97
• /
• 1995

This paper present that the improvment of the effectiveness of a 101진 system is more important than a improvement of efficiency of subsystem in improving process and pro-duction activity. Also, this paper show that how to be taken the priority of the work elements to be improved through algorithm as follows ' 1) Presentation of model process and process analysis. 2) Finding the element of delay time 3) Giving an Inter - Index to each element 4) Sensitivity analysis 5) Making a priority

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.32 no.4
• /
• pp.432-446
• /
• 1996

A stochastic Hamilton variational principle(SHVP) is formulated for dynamic problems of linear continuum. The SHVP allows incorporation of probabilistic distributions into the finite element analysis. The formulation is simplified by transformation of correlated random variables to a set of uncorrelated random variables through a standard eigenproblem. A procedure based on the Fourier analysis and synthesis is presented for eliminating secularities from the perturbation approach. In addition to, a method to analyse stochastic design sensitivity for structural dynamics is present. A combination of the adjoint variable approach and the second order perturbation method is used in the finite element codes. An alternative form of the constraint functional that holds for all times is introduced to consider the time response of dynamic sensitivity. The algorithms developed can readily be adapted to existing deterministic finite element codes. The numerical results for stochastic analysis by proceeding approach of cantilever, 2D-frame and 3D-frame illustrates in this paper.

• Geomechanics and Engineering
• /
• v.6 no.6
• /
• pp.545-560
• /
• 2014

For slope stability analysis, an alternative to the classical limit equilibrium method (LEM) of slices is the shear strength reduction method (SRM), which can be integrated into finite element analysis or finite difference analysis. Recently, probabilistic analysis of earth slopes has been very attractive because it is capable to take the soil uncertainty into account. However, the SRM is less commonly extended to probabilistic framework compared to a variety of probabilistic LEM analysis of earth slopes. To overcome some limitations that hinder the development of probabilistic SRM stability analysis, a new procedure based on recursive algorithm FORM with sensitivity analysis in the space of original variables is proposed. It can be used to deal with correlated non-normal variables subjected to implicit limit state surface. Using the proposed approach, a probabilistic finite element analysis of the stability of an existing earth dam is carried out in this paper.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.149-154
• /
• 2004

The design sensitivity analysis of Zwicker's loudness with respect to structural sizing design variables is developed. The loudness sensitivity in the critical band is composed of two equations, the derivative of main specific loudness with respect to 1/3-oct band level and global acoustic design sensitivities. The main specific loudness is calculated by using FEM, BEM tools. i.e. MSC/NASTRAN and SYSNOISE. And global acoustic sensitivity is calculated by combining acoustic and structural sensitivity using the chain rule. Structural sensitivity is obtained by using semi-analytical method and acoustic sensitivity is implemented numerically using the boundary element method. For sensitivity calculation, sensitivity analyzer of loudness (SOLO), in-house program is developed. A 1/4 scale car cavity model is optimized to show the effectiveness of the proposed method.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1998.03a
• /
• pp.113-116
• /
• 1998

A derivative based approach to process optimal design in powder forging is presented. The process model, the formulation for process optimal design, and the schemes for the evaluation of the design sensitivity, and an iterative procedure for the optimization are described in detail. The validity of the schemes for the evaluation of the design sensitivity is examined by performing numerical tests. The capability of the proposed approach to deal with diverse process parameters and objective functions is demonstrated through applications to some selected process design problems.