• Journal of applied mathematics & informatics
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• 제29권1_2호
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• pp.381-394
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• 2011

In this paper, a Naveir-Stokes equation is solved by using the Adomian's decomposition method (ADM), modified Adomian's decomposition method (MADM), variational iteration method (VIM), modified variational iteration method (MVIM), modified homotopy perturbation method (MHPM) and homotopy analysis method (HAM). The approximate solution of this equation is calculated in the form of series which its components are computed by applying a recursive relation. The existence and uniqueness of the solution and the convergence of the proposed methods are proved. A numerical example is studied to demonstrate the accuracy of the presented methods.

• The Journal of the Acoustical Society of Korea
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• 제17권4E호
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• pp.3-10
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• 1998

This paper concerns the dynamical behavior, in probabilistic sense, of a feedforward neural network performing auto association for novelty. Networks of retinotopic topology having a one-to-one correspondence between and output units can be readily trained using back-propagation algorithm, to perform autoassociative mappings. A novelty filter is obtained by subtracting the network output from the input vector. Then the presentation of a "familiar" pattern tends to evoke a null response ; but any anomalous component is enhanced. Such a behavior exhibits a promising feature for enhancement of weak signals in additive noise. As an analysis of the novelty filtering, this paper shows that the probability density function of the weigh converges to Gaussian when the input time series is statistically characterized by nonsymmetrical probability density functions. After output units are locally linearized, the recursive relation for updating the weight of the neural network is converted into a first-order random differential equation. Based on this equation it is shown that the probability density function of the weight satisfies the Fokker-Planck equation. By solving the Fokker-Planck equation, it is found that the weight is Gaussian distributed with time dependent mean and variance.

• Journal of applied mathematics & informatics
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• 제27권1_2호
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• pp.275-289
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• 2009

In this paper, we investigate the global behavior of the difference equation $x_{n+1}\;=\;\frac{a+bx_{n-1}}{A+Bx^k_n}$, n=0,1,..., where a,b,$B\;{\in}\;[0,\infty)$ and A, $k\;{\in}\;(0,\infty)$ with non-negative initial conditions.

• 한국항공운항학회지
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• 제18권3호
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• pp.21-26
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• 2010

This paper deals with the precise parameter estimation of an air vehicle without a priori information. First, Recursive Least Squares technique, which is an equation error method and does not require any a priori information, is applied and then the extended Kalman filter is used to tune parameters more precisely. To show the performance, a nonlinear longitudinal missile model is simulated and the parameters are estimated. The results show that this consecutive application of the techniques gives a very good estimation performance.

• 소음진동
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• 제8권1호
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• pp.203-211
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• 1998

In order to find out relationship between hit probability and gun firing of a moving tank, a turret and flexible gun system model has been developed using a recursive flexible multibody dynamics. For a firing simulation model, nodal coordinates for a finite element model of a flexible gun have been employed to include transverse loads to the gun tube due to moving bullet and ballistic pressure. Modal coordinates are also used to represent the motion induced gun vibration before a firing occurs. An efficient switching technique from modal equations to nodal equation has been introduced for an entire gun firing simulation with a rotating turret.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.242-245
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• 2009

This paper proposes an algorithm that increases the speed of generating a Fresnel hologram using a recursive addition operation covering the whole coordinate array of a digital hologram. The 3D object designed to calculate the digital hologram used the depth-map image produced by computer graphics (CG). The proposed algorithm is a technique that performs CGH (computer generated hologram) operation with only the recursive addition from the hologram's whole coordinates by analyzing the regularity between the 3D object and the digital hologram coordinates. The experimental results showed that the proposed algorithm increased operation speed by 30% over the technique using the conventional CGH equation.

• Journal of applied mathematics & informatics
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• 제16권1_2호
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• pp.243-249
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• 2004

Our aim in this paper is to investigate the global attractivity of the recursive sequence $x_{n+1}\;=\;\frac{{\alpha}\;-\;{\beta}x_{n-\kappa}}{{\gamma}+x_n}$, where ${\alpha},\;{\beta},\;{\gamma}\;>\;0\;and\;{kappa}\;=\;1,\;2,\;{\ldots}$ We show that the positive equilibrium point of the equation is a global attractor with a basin that depends on certain conditions posed on the coefficients.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1990년도 하계학술대회 논문집
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• pp.60-63
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• 1990

This note presents a direct adaptive pole assignment control for general discrete, linear, time-invariant, nonmimum phase system.Controller parameters are estimated from the recursive least-squares algorithm, and some additional auxiliary parameters are obtained from aset of recursive equations based on a certain polynomial identity which is derived from the pole assignment equation and the Bezout identity. This scheme increase the numerical stability of the auxiliary parameters, and guarantees local convergence without any extra conditions for the external input. The effectiveness of the proposed scheme is demonstrated by the computer simulation.

• 대한전자공학회논문지
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• 제21권2호
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• pp.8-12
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• 1984

비선형 공정제어 문제에서 자주 요구되는 비선형 대수방정식들을 푸는 알고리즘을 제시하고자 한다. 먼저 방정식 변수들을 매개 변수화한 후 순환 식별 기법(recursive identification technique)을 적용하여 새로운 알고리즘을 구성한다. 결과적인 알고리즘의 형태와 그 특성은 Broyden의 Quasi-Newton법과 유사하지만, 그 유도과정과 순환식은 차이가 있으며, Broaden의 방법이 갖고 있는 거의 모든 장점을 갖고 있으면서 몇몇 풀기 어려운 함수에 대하여 더욱 빠르고 믿을 수 있음을 수치 비교로 알 수 있었다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 1999년도 추계종합학술대회
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• pp.475-481
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• 1999

This paper presents a recursive least square estimation algorithm to estimate parameters of the vector controlled induction machine based on measurements of the stator voltage, curents and slip frequency. Due to its recursive structure, this algorithm has the potential to be used for on-line estimation and adaptive control. The algorithm is designed using regression model derived from the motor electrical equation. This model is valid when there is a tittle-scale separation between vector control system and adaptive system. Vector control performed at fast stage and slow stage is in charge of parameters estimation. The performance of tile algorithm is illustrated by means of simulation results and experiment.