• 대한기계학회논문집A
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• 제26권11호
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• pp.2245-2252
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• 2002

Design sensitivity analysis scheme is proposed in an elasto -plastic finite element method with explicit time integration using a direct differentiation method. The direct differentiation is concerned with large deformation, the elasto-plastic constitutive relation, shell elements with reduced integration and the contact scheme. The design sensitivities with respect to the process parameter are calculated with the direct analytical differentiation of the governing equation. The sensitivity results obtained from the present theory are compared with that obtained by the finite difference method in a class of sheet metal forming problems such as hemi-spherical stretching and cylindrical cup deep-drawing. The result shows good agreement with the finite difference method and demonstrates that the preposed sensitivity calculation scheme is a pplicable in the complicated sheet metal forming analysis and design.

• 산업기술연구
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• 제18권
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• pp.233-240
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• 1998

In this study, ride sensitivity analysis of train with non-linear suspension elements is performed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train is parameterized. Equation of motion of the train model is derived, and using the direct differentiation method, sensitivity equations are obtained. For a nominal ride quality performance index, sensitivity analysis with respect to various design parameters regarding non-linear suspension parameters is carried out.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제3권2호
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• pp.161-171
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• 1999

Aerodynamic sensitivity analysis codes are developed via the hand-differentiation using a direct differentiation method and an adjoint method respectively from discrete two-dimensional compressible Navier-Stokes equations. Unlike previous other researches, Baldwin-Lomax algebraic turbulence model is also differentiated by hand to obtain design sensitivities with respect to design variables of interest in turbulent flows. Discrete direct sensitivity equations and adjoint equations are efficiently solved by the same time integration scheme adopted in the flow solver routine. The required memory for the adjoint sensitivity code is greatly reduced at the cost of the computational time by allowing the large banded flux jacobian matrix unassembled. Direct sensitivity code results are found to be exactly coincident with sensitivity derivatives obtained by the finite difference. Adjoint code results of a turbulent flow case show slight deviations from the exact results due to the limitation of the algebraic turbulence model in implementing the adjoint formulation. However, current adjoint sensitivity code yields much more accurate sensitivity derivatives than the adjoint code with the turbulence eddy viscosity being kept constant, which is a usual assumption for the prior researches.

• 한국생활과학회지
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• 제16권2호
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• pp.259-272
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• 2007

The purpose of this study was to investigate the effect of couples' self-differentiation by marital satisfaction according to couple's gender. The participants of the present study were 728 couples who lived in Chonbuk province. The data were collected by self-administered questionnaire method. Self-differentiation scale was consisted of such factors as emotional reactivity, I-position, emotional cut-off and fusion with others. The results of this research were as follows: First, there was significant difference in the level of total self-differentiation between husbands and wives. Second, there was significant difference in the levels of marital conflict and of marital satisfaction to levels of self differentiation. Third, self differentiation in both husbands and wives had an direct effect on marital satisfaction and stability through marital conflict. Fourth, marital conflict in both husbands and wives had a direct effect on marital satisfaction.

• 대한가정학회지
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• 제46권7호
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• pp.95-108
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• 2008

The major purpose of this study was to investigate the effect of intergenerational transmission of self-differentiation on psychological adjustment of college students. Specifically, the present study endeavored to test the causal model focusing on the effect of the father's and the mother's self-differentiation on college student's psychological adjustment through the student's self-differentiation. The data were collected from 254 male and 293 female college students and their parents by using self-administered questionnaire method. The casual model was tested through structural equation model by using AMOS 7.0 program. The results showed that mother's and father's self-differentiation had direct and indirect effect on student's psychological adjustment. The results showed that both mother's and father's self-differentiation had direct effect on son's self-differentiation level, which directly influenced his psychological adjustment. The test of structural equation model also revealed that daughter's self-differentiation level was positively influenced only by mother's self-differentiation, while father's self-differentiation did not influenced female student's self-differentiation. Both male and female student's psychological adjustment was directly influenced by his or her self-differentiation level.

• 한국철도학회논문집
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• 제5권1호
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• pp.40-47
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• 2002

In this study, and analytical method for ride sensitivity analysis of a train with non-linear suspension elements are proposed. Non-linear characteristics of springs and dampers for primary and secondary suspensions of a train are parameterized using polynomial interpolation. Vertical dynamic model of a three-body train running on straight rail with the predetermined roughness expressed in terms of spectral density function is set up and its equations of motion for ride analysis are derived. Using the direct differentiation method, sensitivity equations of the vertical dynamic model with respect to design parameters associated with non-linearity of suspensions are obtained. Based on the sensitivity analysis, improvement of ride is achieved by varying appropriate suspension parameters.

• 한국생활과학회지
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• 제17권4호
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• pp.649-660
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• 2008

The purpose of this study was to investigate the effect of mother's self-differentiation and marital conflict on child's behavior problems. For this purpose, the data were collected from 255 boys and 211 girls and their mothers using self-administered questionaire method by Amos 7.0 program. The results of the study was as follows: First, mother's self-differentiation had a negaitive direct effect on marital conflict. Secondly, marital conflict had a direct effect on boy's behavior problems only. Finally, mother's self-differentiation indirect effect on boy's behavior problems only.

• 대한기계학회논문집A
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• 제20권5호
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• pp.1458-1467
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• 1996

A direct differentiationmethod is presented for the shape design sensitivity analysis of axisymmeetric elastic solids. Based on the exisymmetric boundary integralequaiton formulation, a new boundary ntegral equatio for sensitivity analysis is derived by taking meterial derivative to the same integral identity that was used in the adjoint variable melthod. Numerical implementation is performed to show the applicaiton of the theoretical formulation. For a simple example with analytic solution, the sensitivities by present method are compared with analytic sensitivities. As an application to the shape optimization, an optimal shape of a gas turbine disc toinimize the weight under stress constraints is found by incorporating the sensitivity analysis algorithm in an optimizatio program.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 추계학술대회 논문집
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• pp.93-96
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• 2001

Design sensitivity is calculated in the sheet metal forming process with an elasto-plastic finite element analysis and a direct differentiation method The sensitivity analysis is concerned with the time integration the constitutive relation considering planar anisotropy, shell elements and the contact scheme. The present result is compared with the result obtained with the finite difference approach in deep drawing processes. The obtained sensitivity information is applied to the simple optimization process for the sheet metal forming process.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집C
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• pp.398-401
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• 2001

There are two methods to calculate design sensitivity such as direct differentiation method and adjoint method. A sort of direct differentiation method for design sensitivity analysis costs too much when number of design variables is much larger than the number of response functions whose design sensitivity analyses are required. Therefore, an adjoint method is suggested for the case that the dimension of design variables is lager than the number of response function. An adjoint method is required to compute adjoint variables from the simultaneous linear system equation, the so-called adjoint equation, requiring only the eigenvalue and its associated eigenvectors for mode being differentiated. This method has been extended to the repeated eigenvalue problem. In this paper, we propose an adjoint method for deign sensitivity analysis of damped vibratory systems with distinct eigenvalues.