• Title, Summary, Keyword: Shape design sensitivity

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Shape Design Optimization of Inductive Position Sensor to Improve Sensitivity (유도형 변위 센서의 민감도 향상을 위한 형상 최적 설계)

  • 홍준희;이동주;신우철
    • Proceedings of the Korean Society of Machine Tool Engineers Conference
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    • pp.250-254
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    • 2001
  • The resolution of analog sensor is determined by its sensitivity and amplitude of noise. This paper presents modeling of inductive gap sensor base on equivalent magnetic circuit and analysis of sensitivity. We can simulate static characteristic of inductive gap sensor using this model. Computer simulation show that sensor's sensitivity is affected by magnetic flux's leakage and fringing, and that they are affected by shape of sensor probe. Base on this, we designed shape of inductive position sensor probe.

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Verification of Sensitivity Method for the Design of Optimal Blanks of General Shaped Parts (일반적인 형상의 스탬핑의 최적블랭크 설계를 통한 민감도법의 검증)

  • 손기찬;심현보;황현태
    • Transactions of Materials Processing
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    • v.10 no.1
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    • pp.15-22
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    • 2001
  • The sensitivity method has been utilized to find initial blank shapes which transform into desired shapes after forming. From the information of die shapes, target shape and material properties, the corresponding initial blank which gives final shape after deformation has been found. Drawings of a trapezoidal cup, a cross-shaped cup and an oil pan have been chosen as the examples. At every case the optimal blank shape has been obtained only a few times of modification without any predetermined deformation path. With the predicted optimal blank, both computer simulation and experiment are performed. Excellent agreements are recognized between simulation and experiment at every cases Through the investigation, the sensitivity method is found to be effective in obtaining optimal blank shapes in drawing of complex shapes.

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Conceptual Study of Brain Dedicated PET Improving Sensitivity

  • Shin, Han-Back;Choi, Yong;Huh, Yoonsuk;Jung, Jin Ho;Suh, Tae Suk
    • Progress in Medical Physics
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    • v.27 no.4
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    • pp.236-240
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    • 2016
  • The purpose of this study is to propose a novel high sensitivity neuro-PET design. The improvement of sensitivity in neuro-PET is important because it can reduce scan time and/or radiation dose. In this study, we proposed a novel PET detector design that combined conical shape detector with cylindrical one to obtain high sensitivity. The sensitivity as a function of the oblique angle and the ratio of the conical to cylindrical portion was estimated to optimize the design of brain PET using Monte Carlo simulation tool, GATE. An axial sensitivity and misplacement rate by penetration of ${\gamma}$ rays were also estimated to evaluate the performance of the proposed PET. The sensitivity was improved by 36% at the center of axial FOV. This value was similar to the calculated value. The misplacement rate of conical shaped PET was about 5% higher than the conventional PET. The results of this study demonstrated the conical detector proposed in this study could provide subsequent improvement in sensitivity which could allow to design high sensitivity PET for brain imaging.

Study of Efficient Aerodynamic Shape Design Optimization with Uncertainties (신뢰성을 고려한 효율적인 공력 형상 최적 설계에 대한 연구)

  • 김수환;권장혁
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.34 no.7
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    • pp.18-27
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    • 2006
  • The conventional reliability based design optimization(RBDO) methods require high computational cost compared with the deterministic design optimization(DO) methods, therefore it is hard to apply directly to large-scaled problems such as an aerodynamic shape design optimization. In this study, to overcome this computational limitation the efficient RBDO procedure with the two-point approximation(TPA) and adjoint sensitivity analysis is proposed, that the computational requirement is nearly the same as DO and the reliability accuracy is good compared with that of RBDO. Using this, the 3-D aerodynamic shape design optimization is performed very efficiently.

Shape Design Optimization of Crack Propagation Problems Using Meshfree Methods (무요소법을 이용한 균열진전 문제의 형상 최적설계)

  • Kim, Jae-Hyun;Ha, Seung-Hyun;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.27 no.5
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    • pp.337-343
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    • 2014
  • This paper presents a continuum-based shape design sensitivity analysis(DSA) method for crack propagation problems using a reproducing kernel method(RKM), which facilitates the remeshing problem required for finite element analysis(FEA) and provides the higher order shape functions by increasing the continuity of the kernel functions. A linear elasticity is considered to obtain the required stress field around the crack tip for the evaluation of J-integral. The sensitivity of displacement field and stress intensity factor(SIF) with respect to shape design variables are derived using a material derivative approach. For efficient computation of design sensitivity, an adjoint variable method is employed tather than the direct differentiation method. Through numerical examples, The mesh-free and the DSA methods show excellent agreement with finite difference results. The DSA results are further extended to a shape optimization of crack propagation problems to control the propagation path.

Isogeometric Shape Sensitivity Analysis in Generalized Curvilinear Coordinate Systems (일반 곡면 좌표계에서 구현된 아이소-지오메트릭 형상 설계민감도 해석)

  • Ha, Youn Doh;Yoon, Minho;Cho, Seonho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.6
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    • pp.497-504
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    • 2012
  • Finite element analysis is to approximate a geometry model developed in computer-aided design(CAD) to a finite element model, thus the conventional shape design sensitivity analysis and optimization using the finite element method have some difficulties in the parameterization of geometry. However, isogeometric analysis is to build a geometry model and directly use the functions describing the geometry in analysis. Therefore, the geometric properties can be embedded in the NURBS basis functions and control points so that it has potential capability to overcome the aforementioned difficulties. In this study, the isogeometric structural analysis and shape design sensitivity analysis in the generalized curvilinear coordinate(GCC) systems are discussed for the curved geometry. Representing the higher order geometric information, such as normal, tangent and curvature, yields the isogeometric approach to be the best way for generating exact GCC systems from a given CAD geometry. The developed GCC isogeometric structural analysis and shape design sensitivity analysis are verified to show better accuracy and faster convergency by comparing with the results obtained from the conventional isogeometric method.

ADJOINT METHOD FOR CONTROLLED CAVITATION INVERSE NOZZLE DESIGN

  • Petropoulou, S.;Gavaises, M.;Theodorakakos, A.
    • International Journal of Automotive Technology
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    • v.7 no.3
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    • pp.283-288
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    • 2006
  • A mathematical methodology is proposed for designing nozzle hole shapes producing controlled geometric cavitation. The proposed methodology uses an unstructured RANS flow solver, with the ability to compute sensitivity derivatives via an adjoint algorithm. The adjoint formulation for the N-S equations is presented while variation of the turbulence viscosity is not taken into account during the geometry modifications. The sensitivities are calculated in a mode independently of the shape parameterisation. The method is used to develop and evaluate conceptual shapes for nozzle hole cavitation reduction. The localized region at the hole inlet producing cavitation, is parameterised using its radius of curvature, while a cost function is formulated to eliminate the negative pressures present at this location. Sensitivity derivatives are used to assess the dependence of the localized region on the minimum pressure, and to drive the geometry to the targeted shape. The results show that the computer model can provide nozzle hole entry shapes that produce predefined flow characteristics, and thus can be used as an inverse design tool for nozzle hole cavitation control.

Shape Optimization of Electromagnetic Devices using High Order Derivativ (고차민감도를 이용한 전기기기 형상 최적화)

  • Ahn, Young-Woo;Kwak, In-Gu;Hahn, Song-Yop;Park, Il-Han
    • Proceedings of the KIEE Conference
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    • pp.241-243
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    • 1998
  • This paper describes a new method for the faster shape optimization of the electromagnetic devices. In a conventional iterative method of shape design optimization using design sensitivity based on a finite element method, meshes for a new shape of the model are generated and a discretized system equation is solved using the meshes in each iteration. They cause much design time. To save this time, a polynomial approximation of the finite element solution with respect to the geometric design parameters using Taylor expansion is constructed. This approximate state variable expressed explicitly in terms of design parameters is employed in a gradient-based optimization method. The proposed method is applied to the shape design of quadrupole magnet.

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An Application of Optimal Blank Design by Sensitivity Analysis to Stampings of General Shaped parts (민감도를 이용한 최적블랭크 설계법의 CAD 형식으로 표현된 금형에의 적용)

  • 손기찬
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • pp.45-48
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    • 1999
  • The optimal blank design method by sensitivity analysis has been applied to the formings of oil-pan, tailored blank and front panel have been chosen as the examples. Die shape is prepared by a commercial CAD system. Excellent results has been obtained between the numerical results and the target contour shapes. Through the investigation, the proposed systematic method of optimal blank design is found to be effective in the practical forming processes.

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Shape Design Sensitivity Analysis Using Isogeometric Approach (등기하 해석법을 이용한 설계 민감도 해석)

  • Ha, Seung-Hyun;Cho, Seon-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.3
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    • pp.339-345
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    • 2007
  • In this paper, a variational formulation for plane elasticity problems is derived based on an isogeometric approach. The isogeometric analysis is an emerging methodology such that the basis functions for response analysis are generated directly from NURBS (Non-Uniform Rational B-Splines) geometry. Furthermore, the solution space for the response analysis can be represented in terms of the same functions to represent the geometry, which enables to provide a precise construction method of finite element model to exactly represent geometry using B-spline base functions in CAD geometric modeling and analyze arbitrarily shaped structures without re-meshing. In this paper, a continuum-based adjoint sensitivity analysis method using the isogeometric approach is extensively derived for the plane elasticity problems. The conventional shape optimization using the finite element method has some difficulties in the parameterization of geometry In the isogeometric analysis, however, the geometric properties are already embedded in the B-spline basis functions and control points so that it has potential capability to overcome the aforementioned difficulties. Through some numerical examples, the developed isogeometric sensitivity analysis method is verified to show excellent agreement with finite difference sensitivity.