• 제어로봇시스템학회논문지
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• 제5권7호
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• pp.808-813
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• 1999

A fuzzy learning method to control an unstable and multivariable system is presented in this paper, Because the multivariable system has generally a coupling effect between the inputs and outputs, it is difficult to find its modeling equation or parameters. If the system is unstable, initial condition rules are needed to make it stable because learning is nearly impossible. Therefore, this learning method uses the initial rules and introduces a cost function composed of the actual error and error-rate of each output without the modeling equation. To minimize the cost function, we experimentally got the Jacobian matrix in the operating point of the system. From the Jacobian matrix, we can find the direction of the convergence in the learning, and the optimal control rules are finally acquired when the fuzzy rules are updated by changing the portion of the errors and error rates.

• 소음진동
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• 제4권2호
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• pp.155-161
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• 1994

The dynamic behavior of a complex mechanical structure can be identified by dividing the structure into a series of smaller structure, called sub- structure and by studying the dynamic characteristics of these components. Generally, the dynamic characteristics of mechanical structure are strongly affected by the properties of joint parameters. In this paper, to identify the dynamic characteristics of mechanical structure, and experimental identification method in which directrly measured frequency response function(FRF) is used is considered. The method does not use the procedure of complex matrix calculation but use that of real matrix calculation. To confirm this method, computer simulation is performed by using frequency response function mixed with noise, and the experimental study is performed about the simple structure. The dynamic characteristics of joint parameters and identified more accurately than in using the prcedure of complex matrix calculation.

• 한국정밀공학회지
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• 제16권5호통권98호
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• pp.48-57
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• 1999

Applications of thresholding technique are based on the assumption that object and background pixels in a digital image can be distinguished by their gray level values. For the segmentation of more complex images, it is necessary to resort to multiple threshold selection techniques. This paper describes a new method for multiple threshold selection of gray level images which are not clearly distinguishable from the background. The proposed method consists of three main stages. In the first stage, a probability distribution function for a gray level histogram of an image is derived. Cluster points are defined according to the probability distribution function. In the second stage, fuzzy partition matrix of the probability distribution function is generated through the fuzzy clustering process. Finally, elements of the fuzzy partition matrix are classified as clusters according to gray level values by using max-membership method. Boundary values of classified clusters are selected as multiple threshold. In order to verify the performance of the developed algorithm, automatic inspection process of ball grid array is presented.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제9권1호
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• pp.63-72
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• 2002

An inverse interpolation problem for rational matrix functions with a certain type of symmetricity in zero-pole structure is studied.

• 대한수학회지
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• 제46권2호
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• pp.281-294
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• 2009

Accuracy of the scaling function is very crucial in wavelet theory, or correspondingly, in the study of wavelet filter banks. We are mainly interested in vector-valued filter banks having matrix factorization and indicate how to choose block central symmetric matrices to construct multi-wavelets with suitable accuracy.

• Journal of applied mathematics & informatics
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• 제28권3_4호
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• pp.913-921
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• 2010

The derivative influence measure is adapted to the Cholesky decomposition of a covariance matrix. Formulas for the derivative influence of observations on the Cholesky root and the inverse Cholesky root of a sample covariance matrix are derived. It is easy to implement this influence diagnostic method for practical use. A numerical example is given for illustration.

• 대한수학회지
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• 제44권2호
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• pp.487-498
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• 2007

In this paper, we obtain important combinatorial identities of generalized harmonic numbers using symmetric polynomials. We also obtain the matrix representation for the generalized harmonic numbers whose inverse matrix can be computed recursively.

• Journal of the Korean Statistical Society
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• 제26권3호
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• pp.397-405
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• 1997

Recently maximum likelihood estimators using unconditional likelihood function are used for testing unit roots. When one wants to use this method the determinant term of initial values in the multivariate unconditional likelihood function produces a complicated function of the elements in the coefficient matrix and variance matrix. In this paper an approximation of the determinant term is calculated and based on this aproximation an approximated unconditional likelihood function is calculated. The approximated unconditional maximum likelihood estimators can be used to test for unit roots. When multivariate process has one unit root the limiting distribution obtained by this method and the limiting distribution using exact unconditional likelihood function are the same.

• Korean Journal of Mathematics
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• 제27권2호
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• pp.375-415
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• 2019

We study spaces of continuous-function-valued functions that have the property that composition with evaluation functionals induce $weak^*$ to norm continuous maps to ${\ell}^p$ space ($p{\in}(1,\;{\infty})$). Versions of $H{\ddot{o}}lder^{\prime}s$ inequality and Riesz representation theorem are proved to hold on these spaces. We prove a version of Dixmier's theorem for spaces of function-valued matrix operators on these spaces, and an analogue of the trace formula for operators on Hilbert spaces. When the function space is taken to be the complex field, the spaces are just the ${\ell}^p$ spaces and the well-known classical theorems follow from our results.

• 한국통신학회논문지
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• 제21권1호
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• pp.187-195
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• 1996

The purpose of this paper is to provide an algorithm in which the procedure of constructing a superstate transition matrix for trellis codes is reduced and, as a result, make it easier to evaluate the performance of a TCM scheme when the generalized transfer function method is used. In this paper, an algorithm for constructing a superstate transition matrix and an algorithm for reducing the matrix easily are addressed and applied to an MTCM scheme as an example. It is shown that the algorithm is very useflul for trellis codes with a large number of states and/or parallel transitions.