• Title, Summary, Keyword: 설계 민감도해석

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Transient Response Analysis of a Lumped Mass System Using Sensitivity Method in Time Domain (시간영역 민감도 방법을 이용한 집중 질량 구조물의 천이응답 해석)

  • 백문열;기창두
    • Computational Structural Engineering
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    • v.10 no.3
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    • pp.217-223
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    • 1997
  • This paper deals with the basic concepts of sensitivity analysis in a time domain for the transient response of a lumped mass system. Sensitivity analysis methods in thme domain for determining the effects of parameter changes on the response of a dynamic system by external excitation are presented. The parametric sensitivity of a lumped mass system in time domain can be investigated using different types of sensitivity functions, including first order standard and percentage sensitivity functions. These sensitivity functions are determined as a function of partial derivatives of system variables taken with respect to system parameters. In addition, we compared the results of the analytical method by direct method and those of numerical methods.

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Optimal Positioning of Heating Lines in a Compression Molding Die Using the Boundary Element Method (경계요소법을 이용한 압축성형다이 가열선의 최적위치 설계)

  • 이부윤;조종래
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.17 no.6
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    • pp.1478-1485
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    • 1993
  • A shape optimization problem is formulated to determine the optimal position of heating lines in a compression molding die. The objective of the problem is that the cavity surface would be maintained by a prescribed uniform temperature. A boundary integral equation for the sensitivity of the temperature in terms of hole position is derived using the method of shape design sensitivity analysis. The boundary element method is employed to analyze the temperature and sensitivity field of the die. The sensitivity calculation algorithm is incorporated in an optimization routine. To demonstrate a numerical implementation, an example problem arising in thermal design of a compression molding die is dealt with, showing that the number of heating lines chosen for the die strongly affects the ultimate uniformity of the cavity surface temperature.

Optimization of the Path of Inner Reinforcement for an Automobile Hood Using Design Sensitivity Analysis (설계민감도해석을 이용한 자동차후드 보강경로 최적설계)

  • Lee, Tae-Hui;Lee, Dong-Gi;Gu, Ja-Gyeom;Han, Seok-Yeong;Im, Jang-Geun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.1
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    • pp.62-68
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    • 2000
  • Optimization technique to find a path of an inner reinforcement of an automobile hood is proposed by using design sensitivity informations. The strength and modal characteristics of the automobile hood are analyzed and their design sensitivity analyses with respect to the thickness are carried out using MSC/NASTRAN. Based on the design sensitivity analysis, determination of design variables and response functions is discussed. Techniques improving design from design sensitivity informations are suggested and the double-layer method is newly proposed to optimize the path of stiffener for a shell structure, Using the suggested method, we redesign a new inner reinforcement of an automobile hood and compare the responses with the original design. It is confirmed that new design improved in the frequency responses without the weight increasement.

Design Sensitivity Analysis of Coupled MD-Continuum Systems Using Bridging Scale Approach (브리징 스케일 기법을 이용한 분자동역학-연속체 연성 시스템의 설계민감도 해석)

  • Cha, Song-Hyun;Ha, Seung-Hyun;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.3
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    • pp.137-145
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    • 2014
  • We present a design sensitivity analysis(DSA) method for multiscale problems based on bridging scale decomposition. In this paper, we utilize a bridging scale method for the coupled system analysis. Since the analysis of full MD systems requires huge amount of computational costs, a coupled system of MD-level and continuum-level simulation is usually preferred. The information exchange between the MD and continuum levels is taken place at the MD-continuum boundary. In the bridging scale method, a generalized Langevin equation(GLE) is introduced for the reduced MD system and the GLE force using a time history kernel is applied at the boundary atoms in the MD system. Therefore, we can separately analyze the MD and continuum level simulations, which can accelerate the computing process. Once the simulation of coupled problems is successful, the need for the DSA is naturally arising for the optimization of macro-scale design, where the macro scale performance of the system is maximized considering the micro scale effects. The finite difference sensitivity is impractical for the gradient based optimization of large scale problems due to the restriction of computing costs but the analytical sensitivity for the coupled system is always accurate. In this study, we derive the analytical design sensitivity to verify the accuracy and applicability to the design optimization of the coupled system.

Design Sensitivity Analysis of the Second Order Perturbed Eigenproblems for Random Structural System (불확정 구조계 고유치에 관한 이차 민감도 해석)

  • 임오강;이병우
    • Computational Structural Engineering
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    • v.7 no.3
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    • pp.115-122
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    • 1994
  • Design sensitivity analysis of the second order perturbed eigenproblems for random structural system is presented. Dynamic response of random system including uncertainties for the design variable is calculated with the first order and second order perturbation method to original governing equation. In optimal design methods, there is fundamental requirement for design gradients. A method for calculating the sensitivity coefficients is developed using the direct differentiation method for the governing equation and first order and second order perturbed equation.

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Shape Design Sensitivity Analysis and Optimization of Axisymmetric Shell Structures (축대칭 쉘 구조물의 형상 설계민감도해석 및 최적설계)

  • 김인용;곽병만
    • Computational Structural Engineering
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    • v.7 no.2
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    • pp.147-153
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    • 1994
  • A method for shape design sensitivity analysis for axisymmetric shells of general shapes is developed. The basic approach is to divide the structures into many segments : For each of the segments, the formula for a shallow arch or shell can be applied and the results assembled. To interconnect those segments, the existing sensitivity formula, obtained for a variation only in the direction perpendicular to the plane on which the structure is mapped, has been extended to include a variation normal to the middle surface. The method follows the adjoint variable approach based on the material derivative concept as established in the literature. Numerical examples are taken to illustrate the method and the applicability to practical design problems.

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Sensitivity Analyses on Breakdown Voltage of Cylindrical PN Junctions to the Doping Concentrations (원통형 PN접합의 항복전압의 농도에 대한 민감도)

  • Seo, Hyun-Seok;Jo, Jung-Yol;Ahn, Hee-Tae;Choi, Yearn-Ik
    • Proceedings of the KIEE Conference
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    • pp.59-60
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    • 2006
  • 원통형 PN접합의 Baliga의 해석적인 항복전압에 대한 근사식을 유도하였다. 근사식은 접합길이, $r_j$와 공핍층 깊이, $W_{pp}$의 비 ($r_i/W_{pp}$)가 0.1보다 작은 경우 Baliga식과 잘 일치하였다. 농도에 대한 원통형 접합의 항복전압의 민감도를 유도하였으며, 근사식을 사용한 경우가 Baliga식의 경우보다 민감도식이 더 간단하기 때문에, 민감도를 고려한 소자 설계 시 활용될 수 있으리라 기대된다. 민감도 식을 이용하여 설계한 결과 항복전압의 편차가 10% 이내로 제어하기 위해서는 도핑농도가 $10^{15}cm^{-3}$이고 접합깊이가 $5{\mu}m$ 인 원통형 접합인 경우 농도 편차가 12.8%이내 이어야한다.

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H-refined Shape Design Sensitivity Analysis of Elastic Structures using Multi-Resolution Approach (다중 조밀도를 이용한 탄성 구조의 h-세분화 아이소-지오메트릭 설계민감도 해석)

  • Lee, Taeho;Yoon, Minho;Cho, Seonho;Koo, Bonyong
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.31 no.3
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    • pp.155-163
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    • 2018
  • One of the major disadvantages of isogeometric analysis(IGA) is that local refinement is nearly impossible in a conventional manner because of the tensor product nature in NURBS. In this research, we investigate a local refinement scheme for isogeometric analysis, named multi-resolution approach where different resolutions are employed at each subdomain, using h-refinement relation to endow displacement compatibility on an interface of subdomains. Then, we develop shape sensitivity analysis possessing same compatibility condition as in the analysis. Numerical examples are shown to demonstrate the computational efficiency of the method in analysis especially stress concentration problem and accurate sensitivity results which is also compatible on the interface.

A Study on the Application of Simple Reliability Analysis for Soil Improvement (연약지반개량에 대한 신뢰성해석 간편법의 적용성 연구)

  • Jang, Yeon-Soo;Park, Joon-Mo
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.759-767
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    • 2009
  • Recently, there is a trend to introduce a reliability approach to the design of al large scale improvement of weak ground due to the uncertainty of the influence factors in the consolidation. Since the reliability analysis is not easily adopted to geotechnical engineers because of some difficulties in working up the theories, Duncan(2000) proposed a simplified method for using reliability method to goetechnical problems. In this study, the applicability of Duncan's simplified reliability approach is evaluated by comparing the traditional reliability results with Duncan's. In the sensitivity analysis, the two results were quite similar. However, the probability of failure showed an error range of 20~50% and further Duncan's approach could not make a distinction for the distribution of geotechnical random variables. The simplified reliability method seems to be used properly in preliminary design if it is used supplementary with the deterministic method.

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Optimal Design of Local Induction Heating Coils Based on the Sampling-Based Sensitivity (샘플링 기반 민감도를 이용한 국부 유도 가열용 코일의 최적 설계)

  • Choi, Nak-Sun;Kim, Dong-Wook;Kim, Dong-Hun
    • Journal of the Korean Magnetics Society
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    • v.23 no.3
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    • pp.110-116
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    • 2013
  • This paper proposes a sampling-based sensitivity method for dealing with electromagnetic coupled design problems effectively. The black-box modeling technique is basically applied to obtain an optimum regardless of how strong the electromagnetic, thermal and structural analyses are coupled with each other. To achieve this, Kriging surrogate models are produced in a hyper-cubic local window with the center of a current design point. Then design sensitivity values are extracted from the differentiation of basis functions which consist of the models. The proposed method falls under a hybrid optimization method which takes advantages of the sampling-based and the sensitivity-based methods. Owing to the aforementioned feature, the method can be applied even to electromagnetic problems of which the material properties are strongly coupled with thermal or structural outputs. To examine the accuracy and validity of the proposed method, a strongly nonlinear mathematical example and a coil design problem for local induction heating are tested.