• Journal of applied mathematics & informatics
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• 제7권3호
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• pp.843-859
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• 2000

An Ostrowski type integral inequality for the Riemann-Stieltjes integral ${\int^b}_a$ f(t) du(t), where f is assumed to be of bounded variation on [a, b] and u is of r - H - $H\"{o}lder$ type on the same interval, is given. Applications to the approximation problem of the Riemann-Stieltjes integral in terms of Riemann-Stieltjes sums are also pointed out.

• Journal of applied mathematics & informatics
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• 제12권1_2호
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• pp.107-117
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• 2003

We study the integration problem in which one wants to compute the approximation to the definite integral in the average case setting. We choose the composite Newton- Cotes quadratures as our algorithm and the function values at equally spaced sample points on the given interval［0, 1］as information. We compute the average case error of composite Newton-Cotes quadratures and show that it is minimal (modulo a multi-plicative constant).

• Structural Engineering and Mechanics
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• 제38권6호
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• pp.733-751
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• 2011

In the present study, a new kind of multivariable Reissner-Mindlin plate elements with two kinds of variables based on B-spline wavelet on the interval (BSWI) is constructed to solve the static and vibration problems of a square Reissner-Mindlin plate, a skew Reissner-Mindlin plate, and a Reissner-Mindlin plate on an elastic foundation. Based on generalized variational principle, finite element formulations are derived from generalized potential energy functional. The two-dimensional tensor product BSWI is employed to form the shape functions and construct multivariable BSWI elements. The multivariable wavelet finite element method proposed here can improve the solving accuracy apparently because generalized stress and strain are interpolated separately. In addition, compared with commonly used Daubechies wavelet finite element method, BSWI has explicit expression and a very good approximation property which guarantee the satisfying results. The efficiency of the proposed multivariable Reissner-Mindlin plate elements are verified through some numerical examples in the end.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2000년도 춘계학술대회 학술발표 논문집
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• pp.249-255
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• 2000

HRIV(Hybrid Rule-Interval Variation) method is presented to stabilize a class of nonlinear systems, where SMC(Sliding Mode Control) and ADC (ADaptive Control) schemes are incorporated to overcome the unstable characteristics of a conventional FLC(Fuzzy Logic Control). HRIV method consists of two modes: I-mode (Integral Sliding Mode PLC) and R-mode(RIV method). In I-mode, SMC is used to compensate for MAE(Minimum Approximation Error) caused by the heuristic characteristics of FLC. In R-mode, RIV method reduces interval lengths of rules as states converge to an equilibrium point, which makes the defined Lyapunov function candidate negative semi-definite without considering MAE, and the new uncertain parameters generated in R-mode are compensated by SMC. In RIV method, the overcontraction problem that the states are out of a rule-table can happen by the excessive reduction of rule intervals, which is solved with a dynamic modification of rule-intervals and a transition to I-mode. Especially, HRIV method has advantages to use the analytic upper bound of MAE and to reduce Its effect in the control input, compared with the previous researches. Finally, the proposed method is applied to stabilize a simple nonlinear system and a modified inverted pendulum system in simulation experiments.

• 융합정보논문지
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• 제11권2호
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• pp.124-129
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• 2021

본 논문에서는 절대 안정도를 보장하는 최적의 제어기 설계에 대해 제안하였다. 논문의 적용 순서는 지연시간의 포함여부를 판단하고, 지연시간이 포함되었을 경우 Pade 근사법을 통해서 지연시간을 근사화 한다. 그 다음 공정모델과 제어기 전달함수에 대한 개루프 전달함수를 구하며, Routh-Hurwitz 판별법에 의해서 절대 안정도 구간을 계산한다. 마지막 단계에서는 앞 단계에서 구한 구간을 활용하여 유전자 알고리즘으로 최적의 PID 제어파라미터 값을 구한다. 그 결과 제안 된 방법은 안정성이 보장되며, 최적의 제어기를 설계하여 기존의 방법보다 성능 지표에서 우월함을 확인하였다. 향후 지연시간에 대한 보상방법이 연구된다면 더욱 좋은 성능지표를 얻을 것으로 판단된다.

• Journal of Power Electronics
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• 제13권1호
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• pp.139-160
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• 2013

In this paper, an intelligent robust control system (IRCS) for precision tracking control of permanent-magnet synchronous motor (PMSM) servo drives is proposed. The IRCS comprises a recurrent wavelet-based interval type-2 fuzzy-neural-network controller (RWIT2FNNC), an RWIT2FNN estimator (RWIT2FNNE) and a compensated controller. The RWIT2FNNC combines the merits of a self-constructing interval type-2 fuzzy logic system, a recurrent neural network and a wavelet neural network. Moreover, it performs the structure and parameter-learning concurrently. The RWIT2FNNC is used as the main tracking controller to mimic the ideal control law (ICL) while the RWIT2FNNE is developed to approximate an unknown dynamic function including the lumped parameter uncertainty. Furthermore, the compensated controller is designed to achieve $L_2$ tracking performance with a desired attenuation level and to deal with uncertainties including approximation errors, optimal parameter vectors and higher order terms in the Taylor series. Moreover, the adaptive learning algorithms for the compensated controller and the RWIT2FNNE are derived by using the Lyapunov stability theorem to train the parameters of the RWIT2FNNE online. A computer simulation and an experimental system are developed to validate the effectiveness of the proposed IRCS. All of the control algorithms are implemented on a TMS320C31 DSP-based control computer. The simulation and experimental results confirm that the IRCS grants robust performance and precise response regardless of load disturbances and PMSM parameters uncertainties.

• 정보과학회지
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• 제1권1호
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• pp.72-74
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• 1983

Traditionally, polynomials have been used to approximte functions with prescribed values at a number of points(called the knots) on a given interal on the real line. The method of splines recently developed is more flexible. It approximates a function in a piece-wise fashion, by means of a different polynomial in each subinterval. The cubic spline gas ets origins in beam theory. It possessed continuous first and second deriatives at the knots and is characterised by a minimum curvature property which es rdlated to the physical feature of minimum potential energy of the supported beam. Translated into mathematical terms, this means that between successive knots the approximation yields a third-order polynomial sith its first derivatives continuous at the knots. The minimum curvature property holds good for each subinterval as well as for the whole region of approximation This means that the integral of the square of the second derivative over the entire interval, and also over each subinterval, es to be minimized. Thus, the task of determining the spline lffers itself as a textbook problem in discrete computer programming, since the integral of ghe square of the second derivative can be obviously recognized as the criterion function whicg gas to be minimized. Starting with the initial value of the function and assuming an initial solpe of the curve, the minimum norm property of the curvature makes sequential decision of the slope at successive knots (points) feasible. It is the aim of this paper to derive the cubic spline by the methods of computer programming and show that the results which is computed the all the alues in each subinterval of the spline approximations.

• 한국지능시스템학회논문지
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• 제11권4호
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• pp.293-301
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• 2001

본 논문은 신경회로망과 같은 경험적 모델에서 출력별로 신뢰 구간을 추정하는 세 가지 대표적인 방법을 검토하고, 검토한 방법을 뉴로-퍼지 모델에 적용하여 장단점을 비교 분석한다. 본 논문에서 고려한 출력별 신뢰 구간 계산 방법은 cross-validation을 이용한 stacked generalization, 회귀 모델에서 유도된 predictive error bar, 지역 표현하는 신경회로망의 특성에 기반한 local reliability measure이다. 간단한 함수 근사화 문제와 혼돈 시계열 예측 문제를 이용하여 모의 실험을 수행하고, 세 가지 신뢰도 추정 방법의 성능을 정량적, 정성적으로 비교 분석한다. 분석 결과를 기초로 각 방법의 장단점 및 특성을 고찰하고, 모델링 문제에서 모델의 출력별 신뢰 구간 계산 방법의 실제 적용 가능성을 탐색한다.

• 공업화학
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• 제9권2호
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• pp.294-299
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• 1998

입자당 한 개 이상의 성장라디칼이 있는 일반계에서 근사적인 psedo-homopolymerization (PHP)방법의 신뢰성을 간접적으로 증명하기 위하여, 벌크중합의 Mayo-Lewis식이 Interval II 동안 유화중합의 순간공중합조성식으로부터 확률적으로 유도됨을 보였다. Ballard등에 의하여 제안된 유화공중합의 확장된 Smith-Ewart식으로부터 0-1계(입자당 1개 이하의 성장라디칼이 있는 계)에 대하여 완전해를 얻었다. 이 해를 사용하여 입자당 평균라디칼수와 순간공중합조성이 몇 분 이내에 정상상태에 도달함을 예측할 수 있었다. 따라서 0-1계에 국한하여 PHP근사방법의 신뢰성을 직접 증명할 수 있었다. 모델계산의 목적으로 Styrene-butadiene(St-Bu)과 Styrene-methyl methacrylate(St-MMA)계를 예로 들었다.

• Clinical and Experimental Reproductive Medicine
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• 제2권1호
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• pp.19-38
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• 1975

A total of 185 vasovasostomies were carried out for 11 years. Various factors which are of importance in fluencing the successful vasovasostomies are analysed and presented as follows: In recent years, demand of reanastomosis of the vas deferens increased considerably. An average age of the subjects is 39, and that of their wives, 33 in this series. An average interval between vasectomy and vasovasostomy is 4 years. An average number of living chidren is 2.6 at the time of vasectomy. and 2.1 at the time of time of vasovasostomy. Merchant and public official are the most commonly encounterd occupation in the present series. Coital frequencies are 2.2/week after vasovasostomy. The most common reasons for requesting the vasovasostomy are remarriage and deaths of children, especially son. Success rate is considerably higher among younger group than that of the older. Success rate is somewhat higher among groups of shorter interval between the operations (vasectomy and vasovasostomy) than that of longer interval group. Success rate is higher among bilateral vasovasostomy group than that of any others. Success rate is higher in solid splint group and no splint group than hollow splint group. The closed dressing technique of the end of splint on the scrotum is found to be reasonably effective in preventing infection. Ordinary end-to-end anastomosis and folded side-to-side anastomosis techniques are proved to be the most ideal form of modified operation for the successful vasovasostomies. The most common causes of failure are infection, injuries of blood supply, avascular necrosis due to extensive mobilization, inadequate approximation of both vasal end, hematoma, changes of epididymal environment, and early ambulation in this series. Overall success rate of the author's series is found the 81 per cent, and impregnation rate is 35 per cent. Overall results reported by other workers are that success rate regarding appearance of sperm in the semen after operation is 64 per cent, and that of impregnation after vasovasostomy is 33 per cent. The results of semen assessment performed on same cases prior to vasectomy and following vasovasostomy showed that post-vasovasostomy sperm count scarcely reached three-quaters of pre-vasectomy count.