• 한국정밀공학회지
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• 제31권11호
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• pp.1041-1050
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• 2014

A design and analysis for new foot sensor that measures pressure distribution while walking or running in daily life is introduced. In the process of the sensor design, the shape, mechanism composing of the sensor, and variables that dominate sensor's sensitivity are investigated. Through these variables analysis, an optimal shape and dimension were determined. The effects of variables on sensor's sensitivity and the relationship between each variable are proved by analyses and experiments.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.15-18
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• 1990

In this paper, in order to optimize the shape of electrode to achieve prescribed electric field intensity distribution along the surface of electrode, sensitivity analysis based on finite element method is proposed. The objective function of this problem is the difference of calculated electric field intensity at given design and prescribed electric field intensity. So, the problem is to find the shape of electrode to minimize the objective function defined above. The result of numerical example shows that maximum electric field error is about 0.1% and the usefulness of this shape optimal design procedure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 B
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• pp.929-931
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• 1993

The design sensitivity analysis based on the finite element method is presented for the eddy current problem with a voltage source. Since, in this problem, the complex variable is used as the state variable, new approach to the sensitivity calculation for the complex variable system is required. Its result is applied to the design of the rotor slot shape of squirrel cage induction motor. As a analysis model, only one slot pitch of rotor is analyzed by using a Periodic boundary condition. The use of this minimal modelling method leads to much saving of calculation time. The design objective is to obtain the desired slip-torque characteristic. Because the shape of rotor slot has much influence on the slip torque characteristic, the design variables are taken on the interface shape between rotor core and rotor bar. The initial shape of rotor slot is the trapezoidal type with rounding corners. The obtained final shape is quite similar to the double squirrel cage type.

• Journal of Mechanical Science and Technology
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• 제16권8호
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• pp.1102-1108
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• 2002

In this study, a topological design sensitivity of the ai. bearing surface (ABS) is suggested by using an adjoint variable method. The discrete form of the generalized lubrication equation based on a control volume formulation is used as a compatible condition. A residual function of the slider is considered as an equality constraint function, which represents the slider in equilibrium. The slider thickness parameters at all grid cells are chosen as design variables since they are the topological parameters determining the ABS shape. Then, a complicated adjoint variable equation is formulated to directly handle the highly nonlinear and asymmetric coefficient matrix and vector in the discrete system equation of air-lubricated slider bearings. An alternating direction implicit (ADI) scheme is utilized for the numerical calculation. This is an efficient iterative solver to solve large-scale problem in special band storage. Then, a computer program is developed and applied to a slider model of a sophisticated shape. The simulation results of design sensitivity analysis (DSA) are directly compared with those of FDM at the randomly selected grid cells to show the effectiveness of the proposed approach. The overall distribution of DSA results are reported, clearly showing the region on the ABS where special attention should be given during the manufacturing process.

• 한국전산구조공학회논문집
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• 제25권6호
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• pp.497-504
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• 2012

유한요소 해석법에서는 CAD 모델을 유한요소 모델로 이산화하기 때문에 CAD와 해석 모델의 차이로 인해 형상 설계민감도 및 최적설계에서 설계영역 매개 변수화에 어려움이 있다. 반면에 아이소-지오메트릭 해석법은 CAD 모델과 동일한 NURBS 기저함수와 조정점을 해석에 이용함으로써 설계의 기하학적 변화를 해석모델에 직접적으로 표현할 수 있기 때문에 전술된 여러 어려움들을 개선할 수 있다. 본 연구에서는 일반 곡면 좌표계에서 아이소-지오메트릭 해석 모델을 정식화하여 곡면 부재에 대한 구조해석과 형상 설계민감도 해석을 수행하였다. 아이소-지오메트릭 해석에서는 법선, 접선, 곡률 등과 같은 고차의 기하학적 정보들이 엄밀하게 표현될 수 있기 때문에 주어진 CAD 모델에 적합한 일반 곡면 좌표계를 생성해 낼 수 있다. 기존의 아이소-지오메트릭 구조해석 및 설계민감도 해석 결과와 비교하여 제안된 해석방법론이 더 정확한 해와 더 빠른 수렴성을 보이는 것을 확인하였다.

• 대한전기학회논문지
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• 제39권12호
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• pp.1246-1252
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• 1990

In order to reduce the cogging torque in a permanent magnet motor, a method to optimize the shape of permanent magnet and iron pole is presented. Sine the cogging torque comes from the irregular system energy variation according to the rotor position, system energy variation is taken as object function and the object function is minimized to optimize the shape. The positions of permanent magnet surface and iron pole surface are chosen as design parameters and sensitivity of object function with respect to the design parameter is calculated. The shape is changed according to sensitivity can be generated by methods that exploit the FEM formulation. A numerical example shows that the cogging torque is reduced to about 10% of the original value.

• 한국전산구조공학회논문집
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• 제20권3호
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• pp.339-345
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• 2007

본 논문에서는 등기하 해석법을 이용하여 평면 탄성문제의 변분식을 유도하였다. 등기하 해석법은 새로이 부각되고 있는 해석법으로서 기저 함수가 NURBS(Non-Uniform Rational B-Splines) 로부터 직접 생성되므로 해 공간은 CAD 모델을 구성하는 함수로써 표현된다. 또한 CAD 모델의 B-Spline 기저 함수를 직접 사용하므로 기하학적으로 엄밀한 형상을 표현할 수 있고 요소망의 재구성 없이 해석모델을 정밀화(Refinement)할 수 있는 강점이 있다. 본 논문에서는 이를 확장하여 연속체 기반의 애드조인트 설계 민감도 해석법을 사용하는 등기하 설계민감도 해석법을 유도하였다. 기존의 유한요소 기반형상 최적설계는 형상의 매개화에 어려움을 겪었으나 등기하 기반 최적설계에서는 기하학적 정보가 이미 B-spline 기저함수와 조정점에 포함되어 있으므로 이러한 어려움을 피할 수 있는 잠재력을 가지고 있다. 몇몇 수치 예제를 통해서 등기하 해석법을 사용한 설계 민감도 해석을 수행하였으며 유한차분 민감도와 비교하여 정확성을 확인하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1999년도 추계학술대회논문집
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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.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1993년도 가을 학술발표회논문집
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• pp.98-105
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• 1993

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.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제54권4호
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• pp.163-173
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• 2005

The conventional optimization study for electromagnetic systems has been mostly on the shape or size optimization. The goal for these optimization methods is to improve performance of electromagnetic systems by optimizing the interface shape of two different materials while their given layout or initial topology are held. The feasible topology can be diverse and an appropriate topology will give much better design results. In this paper we propose a theory and an algorithm for topology optimization of electromagnetic systems, which are based on the finite element method. The topology optimization technique employes a direct searching method of sensitivity analysis in which the information of material sensitivity is used. Two numerical examples of a switched reluctance motor and an electrostatic actuator of MEMS are tested and their design results show that the optimization method is valid and useful for the topology and basic layout design of electromagnetic systems.