• International Journal of Precision Engineering and Manufacturing
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• 제1권2호
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• pp.76-83
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• 2000

A study on the robust control of a composite beam with a distributed PVDF sensor and piezo-ceramic actuator is presented in this paper. $1^{st}$ and $2^{nd}$ natural frequencies are considered in the modeling, because robust control theory which has robustness to structured uncertainty is adopted to suppress the vibration. If the controllers designed by $H_{\infty}$ theory do not satisfy control performance, it is improved by $\mu$-synthesis method with D-K iteration so that the $\mu$-controller based on the structured singular value satisfies the nominal performance and robust performance. Simulation and experiment were carried out with the designed controller and the verification of the robust control properties was presented by results.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
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• pp.69-76
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• 2002

In this paper, several improved Element-Free Galerkin (EFG) methods containing singular expression in their approximation functions are compared one another through a patch test with near-tip field. Intrinsic enrichments that expand the basis function partially and fully with known near-tip displacement field and a local enrichment using auxiliary supports based on the partition of unity concept are examined by evaluating a relative stress norm error and the stress intensity factor. Some numerical examinations graphically show that how the size of compact support, dilation parameter and the diffraction parameter can affect the accuracy of the improved EFG methods in the error and the stress intensity factor.

• Coupled systems mechanics
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• 제9권1호
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• pp.77-89
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• 2020

This study is dedicated to the dynamic elasticity problem for a semi-strip. The semi-strip is loaded by the dynamic load at the center of its short edge. The conditions of fixing are given on the lateral sides of the semi-strip. The initial problem is reduced to one-dimensional problem with the help of Laplace's and Fourier's integral transforms. The one-dimensional boundary problem is formulated as the vector boundary problem in the transform's domain. Its solution is constructed as the superposition of the general solution for the homogeneous vector equation and the partial solution for the inhomogeneous vector equation. The matrix differential calculation is used for the deriving of the general solution. The partial solution is constructed with the help of Green's matrix-function, which is searched as the bilinear expansion. The case of steady-state oscillations is considered. The problem is reduced to the solving of the singular integral equation. The orthogonalization method is applied for the calculations. The stress state of the semi-strip is investigated for the different values of the frequency.

• 한국안광학회지
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• 제6권2호
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• pp.121-127
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• 2001

additive 감쇠에 의한 감쇠 최소 자승법에 가우스 소거법과 Jacobian 행렬을 직교 변환시킨 SVD(singular value decomposition)법을 적용하여 조건수가 양호한 triplet 사진 렌즈계에 적용하여 수렴 속도와 안정성을 비교하였다. SVD 직교화 방법을 적용한 감쇠 최소 자승 법이 최소 merit 함수에 보다 안정되고 빠르게 수렴하였다. SVD 방법을 적용한 최적화에서 적절한 merit 함수를 얻을 수 있지만 오차 함수의 비선형성으로 인해 merit 함수가 국부 최소 점에 수업하는 경우가 있어서 간단한 전역 최적화 방법인격자 법으로 최적화를 실시하여 SVD 방법에 의한 merit 함수보다 낮은 전역 최소 점에 수렴하게 하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 추계학술대회 논문집 학회본부
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• pp.23-27
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• 1990

Adaptive mesh refinement scheme is incorporated with the Boundary Element Method (BEM) in order to get accurate solution with relatively fewer unknowns for the case of magnetostatic field analysis and A new and simple posteriori local error estimation method is presented. The local error is defined as integration over the element of the difference between solutions acquired us ing second order and first order interpolation function and is used as the criterion for mesh refinement at given grid. Case study for two dimensional problems with singular point reveals that meshes are concentrated on the neighbor of singular point and the error is decreased gradually and the solutions calculated on the domain are converged to the analytic solution as the number of unknowns increases. The adaptive mesh gives much better rate of convergence in global errors than the uniform mesh.

• 한국기계연구소 소보
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• 통권19호
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• pp.81-92
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• 1989

This paper presents a simple identification method of the actual kinematic parameters for the robot with parallel joints. It is known that Denavit-Hartenberg's coordinate system is not useful for nearly parallel joints. In this paper, the coordinate frames are reassigned to model the kinematic parameter between nearly parallel joints by four parameters. The proposed identification method uses a straight ruler about 1m long. A robot hand is placed by using a teaching pendant at the prescribed points on the ruler, and corresponding error function is defined. The identified kinematic parameters which make the error function zero are obtained by iterative least square error method based on the singular value decomposition. In the compensation of joint angles, only the position is considered because the usual applications of robot do not require a precise orientation control.

• 대한수학회지
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• 제36권2호
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• pp.355-367
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• 1999

We prove the existence of 2N-1 distinct ordered positive solutions of a class of semilinear elliptic Dirichlet boundary value problems on Rn when the forcing term has N distinct positive stable zeros and the coefficient function decaying to the zero at infinity.

• 호남수학학술지
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• 제30권1호
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• pp.137-146
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• 2008

Many fractal objects observed in reality are characterized by some irregularities or complexities in their features. These properties can be measured and analyzed by means of fractal dimension. However, in many cases, the calculation of this value may not be so easy to utilize in applications. In this respect, we have treated a formal method to estimate the dimension of fractal curves.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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• pp.12-12
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• 2000

This paper consider a new weighted model reduction using block diagonal solutions of Lyapunov inequalities. With the input and/or output weighting function, the stability of reduced order system is quaranteed and a priori error bound is proposed. to achieve this, after finding the solutions of two Lyapunov inequalities and balancing the full order system, we find the reduced order systems using the direct truncation and the singular perturbation approximation. The proposed method is compared with other existing methods using numerical example.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제1권1호
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• pp.29-33
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• 1994

There are various aspects of the solution of boundary-value problems for second-order linear elliptic equations in two independent variables. One useful method of solving such boundary-value problems for Laplace's equation is by means of suitable integral representations of solutions and these representations are obtained most directly in terms of particular singular solutions, termed Green's functions.(omitted)