• 대한기계학회논문집A
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• 제25권1호
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• pp.153-160
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• 2001

A general procedure for the design sensitivity analysis of structural dynamic problems has been presented in frame of the FRF-based substructuring formulation. For a system response function, the proposed method gives a parametric design sensitivity formula in terms of the partial derivatives of the connection element properties and the transfer matrix of the subsystems. The derived design sensitivity formula is applied to an engine mount system. An interior noise problem in the passenger car is analyzed using the FRF-based substructuring method and the proposed formulation is adopted to study the response variations with respect to the dynamic characteristics of the engine mounts and the bushes. To obtain the FRFs, a finite element model is built for the engine mount structures, and test data is used for the trimmed body including cabin cavity. The comparison of sensitivities derived by the proposed method and the finite difference method shows that the proposed method is efficient and accurate. The proposed sensitivity analysis method indicates effectively the most sensitive location to the interior noise among the engine mounts and the bushes.

• Journal of Ship and Ocean Technology
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• 제11권4호
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• pp.29-54
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• 2007

Systematic sensitivity analysis of smoothed particle hydrodynamics method (SPH), a gridless Lagrangian particle method, was carried out in this study. Unlike traditional grid-based numerical schemes, systematic sensitivity study for computational parameters is very limited for SPH. In this study, the effect of computational parameters in SPH simulation is explored through two-dimensional dam-breaking and sloshing problem. The parameters to be considered are the speed of sound, the type of kernel function, the frequency of density re-initialization, particle number, smoothing length and pressure extraction method. Through a series of numerical test, detailed information was obtained about how SPH solution can be more stabilized and improved by adjusting computational parameters.

• 산업기술연구
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• 제26권B호
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• pp.83-92
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• 2006

A probabilistic analysis model. one of reliability analysis methods introducing the concept of variables, was developed to investigate the uncertainty of dominant factors influencing the degree of consolidation in the radial consolidation theories. Based on the developed probabilistic analysis model, sensitivity study of those factors was performed to find their trends of affecting the degree of consolidation in the vertical drain method. Various radial consolidation theories, proposed by Barron(1948), Hansbo(1979), Yoshikuni(1979) and Onoue(1988), were used for this parametric study with the influencing factors such as size of smear zone, reduction ratio of permeability in the smear zone, discharge capacity, permeability for horizontal flow and coefficient of consolidation for horizontal flow. As results of this sensitivity study, for the given consolidation theory, contribution of each factor to the degree of consolidation was figure out and compared to each other. For the given value of each factor, the sensitivity to the degree of consolidation in the various theories was evaluated and their applicability and limitations were assessed.

• 한국항공우주학회지
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• 제43권4호
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• pp.368-376
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• 2015

본 논문은 헬리콥터 초기 설계를 위해 수정된 추정식을 적용한 헬리콥터 초기 설계 모델 정립 연구의 응용에 대한 내용으로 헬리콥터 초기 설계의 효율성을 제고하고 개선하고자 하였다. 헬리콥터 설계 시 중량계수 영향성을 확인하고 적정한 중량계수 적용방법을 제시하였으며, 중량계수 및 회전면 하중, 블레이드 개수, 블레이드 종횡비와 같은 주요 매개변수에 대한 민감도 분석과 연관관계에 대해 고찰하였다. 연구 결과, 설계 시 변수에 대한 연관관계 및 민감도의 양을 고려하여 설계 할 헬기 특성을 최적화해야하며, 주요 매개변수들 사이에는 복합적인 연관관계가 존재하므로 설계 시 설계자는 설계 인자들에 대한 신중한 고려가 필요한 것으로 분석되었다.

• Nuclear Engineering and Technology
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• 제55권1호
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• pp.131-143
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• 2023

Constitutive equations in a nuclear reactor safety analysis code are mostly empirical correlations developed from experiments, which always accompany uncertainties. The accuracy of the code can be improved by modifying the constitutive equations fitting wider range of data with less uncertainty. Thus, the sensitivity of the code with respect to the constitutive equations is evaluated quantitatively in the paper to understand the room for improvement of the code. A new methodology is proposed which first starts by dividing the thermal hydraulic conditions into multiple sub-regimes using self-organizing map (SOM) clustering method. The sensitivity analysis is then conducted by multiplying an arbitrary set of coefficients to the constitutive equations for each sub-divided thermal-hydraulic regime with SOM to observe how the code accuracy varies. The randomly chosen multiplier coefficient represents the uncertainty of the constitutive equations. Furthermore, the set with the smallest error with the selected experimental data can be obtained and can provide insight which direction should the constitutive equations be modified to improve the code accuracy. The newly proposed method is applied to a steady-state experiment and a transient experiment to illustrate how the method can provide insight to the code developer.

• 한국정밀공학회지
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• 제20권11호
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• pp.180-187
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• 2003

A CAD-based seamless design system for MEMS named DS/MEMS was developed which performs coupled-field analysis, optimal and robust design. DS/MEMS has been developed by means of integrating commercial codes and inhouse code-SolidWorks, FEMAP, ANSYS and CA/MEMS. This strategy results in versatility that means to include various analysis model, corresponding analyses and approximated design sensitivity analysis and user friendliness that design variables are taken to be selectable directly from a CAD model, that the problem is formulated under a window environment and that the manual job during optimization process is almost eliminated. DS/MEMS works on a parametric CAD platform, integrating CAD modeling, analysis, and optimization. Nonlinear programming algorithms, the Taguchi method, and response surface method are made available for optimization. One application problem is taken to illustrate the proposed methodology and show the feasibility of DS/MEMS as a practical tool.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 봄 학술발표회 논문집
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• pp.301-308
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• 1999

The construction of great deep tunnels has become an important part in tunnel construction especially in the mountain area. Therefore, it is necessary to establish the proper method of the stability analysis for great deep tunnels. In this paper presents the study result on the followings: (1) Evaluation of practical problem on the stability analysis of great deep tunnels. (2) Proposal of the proper on method for great deep tunnels analysis considering the depth of overburden. (3) Understanding of the ground behavior of the great deep tunnel through the sensitivity analysis and the parametric study.

• Nuclear Engineering and Technology
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• 제54권3호
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• pp.790-802
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• 2022

Large-scale reactor simulation often requires the use of Monte Carlo calculation techniques to estimate important reactor parameters. One drawback of these Monte Carlo calculation techniques is they inevitably result in some uncertainty in calculated quantities. The present study includes parametric uncertainty quantification (UQ) and sensitivity analysis (SA) on the Advanced Test Reactor Critical (ATRC) facility housed at Idaho National Laboratory (INL) and addresses some complications due to Monte Carlo uncertainty when performing these analyses. This approach for UQ/SA includes consideration of Monte Carlo code uncertainty in computed sensitivities, consideration of uncertainty from directly measured parameters and a comparison of results obtained from brute-force Monte Carlo UQ versus UQ obtained from a surrogate model. These methodologies are applied to the uncertainty and sensitivity of k_eff for two sets of uncertain parameters involving fuel plate geometry and fuel plate composition. Results indicate that the less computationally-expensive method for uncertainty quantification involving a linear surrogate model provides accurate estimations for k_eff uncertainty and the Monte Carlo uncertainty in calculated k_eff values can have a large effect on computed linear model parameters for parameters with low influence on k_eff.

• 융복합기술연구소 논문집
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• 제4권2호
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• pp.11-15
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• 2014

Magnet gear transfers a high speed torque of the driving side to a low speed following side. Of course, the torque is amplified as much as a ratio between pole number of magnet gears constituting both sides through ferromagnet modulator. However, the parameters of the overall magnetic system influence the transmitting torque strongly. They include a pole number of permanent magnet, magnet thickness, reducing ratio, harmonic modulator thickness, and open ratio etc. In this paper, the influences of the parameters are analyzed using finite element method tool. By comparison, a desirable design specification is proposed, including a recommended modulator pattern.

• 설비공학논문집
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• 제12권6호
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• pp.599-608
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• 2000

One dimensional numerical modeling was carried out for the melting behavior of dry snow and the unsaturated flow when heat was supplied from the bottom surface. Discrepancy between the previous experimental data and the present numerical results is substantially reduced by considering the density change of water permeation layer due to the infiltration of meltwater. In the parametric study for effective thermal conductivity, it was found that the effect of this parameter to the behavior of snow melting is minor. Sensitivity analysis showed that the melting time is most sensitive to changes in supplied heat flux, snow temperature, and bulk density, whereas snow bulk density and residual saturation have a significant effect on the height of water permeation layer in snow.