• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 D
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• pp.2759-2761
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• 2001

Sliding mode is a robust control method and can be applied in the presence of model uncertainties and parameter disturbances. But there ane problems in sliding mode controller. Hard in modeling system parameters, chattering, etc. In this paper, new sliding controller design method is proposed for solving the above problems using fuzzy sliding mode contros(FSMC) scheme are considered. we propose that fuzzy logic system are used to approximate unknown system functions in desinging the SMC of Inverted Pendulum. In the method, a fuzzy logic system is utilized to approximate the unknown function f of the nonlinear system. As a simulation result of applying the inverted pendulum, the sliding controller shows good robust characteristics.

• Structural Engineering and Mechanics
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• 제3권1호
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• pp.61-74
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• 1995

A linearly tapered, doubly symmetric thin-walled closed member, such as power-transmission towers and tourist towers, are often characterized by local variation in mass and/or rigidity, due to additional mass and rigidity. On the preliminary stage of design the closed-form solution is more effective than the finite element method. In order to propose approximate solutions, the discontinuous and local variation in mass and/or rigidity is treated continuously by means of a usable function proposed by Takabatake(1988, 1991, 1993). Thus, a simplified analytical method and approximate solutions for the free and forced transverse vibrations in linear elasticity are demonstrated in general by means of the Galerkin method. The solutions proposed here are examined from the results obtained using the Galerkin method and Wilson-${\theta}$ method and from the results obtained using NASTRAN.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2001년도 춘계학술대회 학술발표 논문집
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• pp.65-68
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• 2001

RBFN has some problem that because the basis function isnt orthogonal to each others the number of used basis function goes to big. In this reason, the Wavelet Neural Network which uses the orthogonal basis function in the hidden node appears. In this paper, we propose the composition method of the actual function in hidden layer with the scaling function which can represent the region by which the several wavelet can be represented. In this method, we can decrease the size of the network with the pure several wavelet function. In addition to, when we determine the parameters of the scaling function we can process rough approximation and then the network becomes more stable. The other wavelets can be determined by the global solutions which is suitable for the suggested problem using the genetic algorithm and also, we use the back-propagation algorithm in the learning of the weights. In this step, we approximate the target function with fine tuning level. The complex neural network suggested in this paper is a new structure and important simultaneously in the point of handling the determination problem in the wavelet initialization.

• 한국지능시스템학회논문지
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• 제21권6호
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• pp.737-742
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• 2011

주행문제는 불확실한 외란의 영향을 받는 이동로봇 등의 시스템에 대하여 각종 제약조건들을 만족하도록 하는 제어 입력을 결정하는 과제를 포함한다. 이러한 과제는 제약조건을 갖는 확률 제어 문제로 모델링될 수 있다. 이러한 종류의 제어문제를 풀기 위하여, 최적 가치함수 개념에 의존하는 동적 계획법의 활용을 시도해볼 수 있다. 하지만, 대부분의 실제 문제에서 이러한 시도는 많은 어려움, 예컨대, 시스템의 완벽한 모델이 알려지지 않거나, 최적 제어정책을 구하기 위한 계산이 불가능하거나, 수없이 많은 계산 자원을 필요로 하는 등의 문제점을 안겨줄 수 있다. 이러한 동적 계획법의 어려움을 극복하기 위한 전략으로, 근사적 가치함수에 의존하여 준최적 제어정책을 구하는 근사적 동적 계획법을 사용할 수 있다. 본 논문에서는 최근에 제시된 근사 동적 계획법들을 복잡한 제약조건을 갖는 주행 문제에 적용하여 보고 그 결과로 얻어지는 성능 특성을 관찰해 본다.

• 한국해양공학회지
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• 제35권2호
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• pp.141-149
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• 2021

The A60 class deck penetration piece is a fire-resistance apparatus installed on the deck compartment to protect lives and to prevent flame diffusion in the case of a fire accident in a ship or offshore plant. In this study, the sensitivity of the fire-resistance performance and approximation characteristics for the A60 class penetration piece was evaluated by conducting a transient heat-transfer analysis and fire test. The transient heat-transfer analysis was conducted to evaluate the fire-resistance design of the A60 class deck penetration piece, and the analysis results were verified via the fire test. The penetration-piece length, diameter, material type, and insulation density were used as the design factors (DFs), and the output responses were the weight, temperature, cost, and productivity. The quantitative effects of each DF on the output responses were evaluated using the design-of-experiments method. Additionally, an optimum design case was identified to minimize the weight of the A60 class deck penetration piece while satisfying the allowable limits of the output responses. According to the design-of-experiments results, various approximate models, e.g., a Kriging model, the response surface method, and a radial basis function-based neural network (RBFN), were generated. The design-of-experiments results were verified by the approximation results. It was concluded that among the approximate models, the RBFN was able to explore the design space of the A60 class deck penetration piece with the highest accuracy.

• 대한기계학회논문집A
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• 제20권7호
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• pp.2167-2173
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• 1996

An approximate weight function technique using the indirect boundary integral equation has been presented for the analysis of stress intensity foactors(SIFs) of a thick pipe. One-term boundary integral was introduced to represent the crack surface displacement field for the displacement based weight function technique. An explicit closed-form SIF solution applicable to symmetric cracked pipes without any modification of the solution including both circumferential and radial cracks has been derived. The necessary information in the analysis is two or three reference SIFs. In most cases the SIF solution were in good agreement with those available in the literature.

• Structural Engineering and Mechanics
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• 제67권4호
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• pp.327-336
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• 2018

In this study, an efficient damage index is proposed to identify multiple damage cases in structural systems using the concepts of frequency response function (FRF) matrix and strain energy of a structure. The index is defined based on the change of strain energy of an element due to damage. For obtaining the strain energy stored in elements, the columnar coefficients of the FRF matrix is used. The new indicator is named here as frequency response function strain energy based index (FRFSEBI). In order to assess the performance of the proposed index for structural damage detection, some benchmark structures having a number of damage scenarios are considered. Numerical results demonstrate that the proposed index even with considering noise can accurately identify the actual location and approximate severity of the damage. In order to demonstrate the high efficiency of the proposed damage index, its performance is also compared with that of the flexibility strain energy based index (FSEBI) provided in the literature.

• 정보처리학회논문지A
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• 제9A권2호
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• pp.267-270
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• 2002

비중심 $\chi^2$분포의 누적분포 함수의 계산은 $\chi^2$검정에서 검정력 계산에 요구된다. 본 논문서는 중심 $\chi^2$분포 함수를 통하여 비중심 $\chi^2$분포 함수의 계산을 구하는 알고리즘을 제시하고 있으며 기존의 접근 방법에 의한 계산 결과와 비교하였다.

• 한국생산제조학회지
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• 제24권2호
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• pp.186-191
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• 2015

Presently, rapidly changing and unstable global economic environments demand engineers. Products should be designed to increase profits by lowering costs and provide distinguished performance compared with competitors. This study aims to optimize the design of the power-transmission drive shaft. The mass is reduced as an objective function, and the stress is constrained under a constant value. To reduce the number of experiments, CCD (central composite design) and D-Optimal are used for the experimental design. RSM (response surface methodology) is employed to construct a regression model for the objective functions and constraint function. In this problem, there is only one objective function for the mass. The other objective function gives 1; thus, NSGA-II is used.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.874-879
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• 1992

It is shown that there exists a nonlinear mappping which transforms features and their changes to the desired camera motion without measurement of the relative distance between the camera and the part, and the nonlinear mapping can eliminate several difficulties encountered when using the inverse of the feature Jacobian as in the usual feature-based visual feedback controls. And instead of analytically deriving the closed form of such a nonlinear mapping, a fuzzy membership function (FMF) based neural network is then proposed to approximate the nonlinear mapping, where the structure of proposed networks is similar to that of radial basis function neural network which is known to be very useful in function approximations. The proposed FMF network is trained to be capable of tracking moving parts in the whole work space along the line of sight. For the effective implementation of proposed IMF networks, an image feature selection processing is investigated, and required fuzzy membership functions are designed. Finally, several numerical examples are illustrated to show the validities of our proposed visual servoing method.