• 제어로봇시스템학회논문지
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• 제3권4호
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• pp.398-405
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• 1997

This article presents a new model which is called Periodic Square-Wave(PSW) to describe the material flow of the periodic processes involving intermediate buffer. The material flows incoming into and outgoing from the intermediate buffer are assumed to be periodic square shaped. PSW model gives the same result as that of Economic Production Quantity(EPQ) model for determining optimal lot size of single stage batch storage system. However, for batch storage serial train system, PSW model gives a different optimal solution of about 6 % reduced total cost. PSW model provides the more accurate information on inventory and production system than the classical approach by maintaining simplicity and increasing computational burden.

• Journal of applied mathematics & informatics
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• 제19권1_2호
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• pp.261-280
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• 2005

We study the existence and nonexistence of positive periodic solutions of a non-autonomous functional differential equation with impulses. The equations we study may be of delay, advance or mixed type functional differential equations and the impulses may cause the existence of positive periodic solutions. The methods employed are fixed-point index theorem, Leray-Schauder degree, and upper and lower solutions. The results obtained are new, and some examples are given to illustrate our main results.

• Journal of applied mathematics & informatics
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• 제29권1_2호
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• pp.279-292
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• 2011

In this paper, we consider anti-periodic solutions of the following BAM neural networks with multiple delays on time scales: $$\{{x^\Delta_i(t)=-a_i(t)e_i(x_i(t))+{\sum\limits^m_{j=1}}c_{ji}(t)f_j(y_j(t-{\tau}_{ji}))+I_i(t),\atop y^\Delta_j(t)=-b_j(t)h_j(y_j(t))+{\sum\limits^n_{i=1}}d_{ij}(t)g_i(x_i(t-{\delta}_{ij}))+J_j(t),}\$$ where i = 1, 2, ..., n,j = 1, 2, ..., m. Using some analysis skills and Lyapunov method, some sufficient conditions on the existence and exponential stability of the anti-periodic solution to the above system are established.

• 대한수학회지
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• 제44권3호
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• pp.511-523
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• 2007

We consider a two parametric family of the planar systems with the form $\dot{x}=P(x,\;y)+{\in}_1p_1(x,\;y)+{\in}_2p_2(x,\;y)$, $\dot{y}=Q(x,\;y)+{\in}_1p_1(x,\;y)+{\in}_2p_2(x,\;y)$, where the unperturbed equation(${\in}_1={\in}_2=0$) is assumed to have at least one periodic solution or limit cycle. Our aim here is to study the behavior of the system under two parametric perturbations; in fact, using the Poincare-Andronov technique, we impose conditions on the system which guarantee persistence of the periodic trajectories. At the end, we apply the result on the Van der Pol equation ; where, we consider the effect of nonlinear damping on the equation. Also the Hopf bifurcation for the Van der Pol equation will be investigated.

• Journal of applied mathematics & informatics
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• 제27권3_4호
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• pp.501-515
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• 2009

A second order nonlinear ordinary differential equation is obtained by solving the initial-boundary value problem of a class of elas-todynamics equations, which models the radially symmetric motion of a incompressible hyper-elastic solid sphere under a suddenly applied surface tensile load. Some new conclusions are presented. All existence conditions of nonzero solutions of the ordinary differential equation, which describes cavity formation and motion in the interior of the sphere, are presented. It is proved that the differential equation has singular periodic solutions only when the surface tensile load exceeds a critical value, in this case, a cavity would form in the interior of the sphere and the motion of the cavity with time would present a class of singular periodic oscillations, otherwise, the sphere remains a solid one. To better understand the results obtained in this paper, the modified Varga material is considered simultaneously as an example, and numerical simulations are given.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.1101-1106
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• 2003

As the disk in the ODD rotates, disturbances acting on the ODD servo system generally have periodic components. Such disturbances can make the system unstable and make the controller hard to work. The repetitive controller can be the solution of the periodic disturbances by making the periodic control signals. In this paper repetitive controller is proposed that make the control signal follow the periodic disturbances. A low pass filter, which can make the system stable, is proposed by the simple stability conditions. We will show the performance of the repetitive controller in actual commercial system. Simulation and experimental results will be given as the evidences

• 한국정보통신학회논문지
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• 제3권1호
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• pp.113-120
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• 1999

Chua 발진기의 카오스 신호를 선형 상태 피드백 제어 이론을 적용하여 평형점, 1주기, 2주기의 신호로 제어하는 방법을 제안하였다. 제안한 선형 상태 피드백 이득 값을 리아프노프 함수를 이용하여 Chua 오실레이터가 나타내는 모든 카오스 현상을 제어할 수 있도록 파라미터 부호의 조합에 의해 4가지로 분류하였다. 본 논문의 상태 피드백 제어 기법은 시스템의 카오스 상태에서 얻고자 하는 상태(평형점, 주기 신호등)로 효율적으로 제어 가능하고, 매우 간단한 구조로 파라미터의 변화 없이 최소의 입력으로 가능케 하였다.

• 한국소음진동공학회논문집
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• 제12권11호
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• pp.897-903
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• 2002

The periodic high vibration has been occurred one or two times a day for a 500 MW large steam turbine during 5 months. This abnormal vibration was caused by the rubbing between the rotor and the carbide accumulated on the seal tooth of oil deflector. It was found that the accumulated carbide was insulation material installed on the HIP casing from the examination of the chemical composition. Also, this paper presents the mechanism of the periodic high vibration and the proper method to eliminate this vibration problem. This result would be good practice to find the solution of similar high vibration in the steam turbines for power plant as well as industrial rotating machineries.

• Journal of applied mathematics & informatics
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• 제10권1_2호
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• pp.119-130
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• 2002

An extended Jacobin elliptic function method is presented for constructing exact travelling wave solutions of nonlinear partial differential equations(PDEs) in a unified way. The main idea of this method is to take full advantage of the elliptic equation that Jacobin elliptic functions satisfy and use its solutions to replace Jacobin elliptic functions in Jacobin elliptic function method. It is interesting that many other methods are special cases of our method. Some illustrative equations are investigated by this means.

• 한국소음진동공학회논문집
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• 제17권1호
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• pp.41-47
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• 2007

Scattering fields of two dimensional acoustic waves by a circular cylinder are investigated. The present numerical approach for the acoustic scattering problem has difficulties of numerical robustness, long-time stability and suitability of far-field boundary treatments. The time-dependent periodic acoustic source is used to analyze Interference patterns between incident waves and waves reflected by the cylinder. Characteristic boundary algorithms coupled with 4th order Modified-Flux-Approach ENO(essentially non-oscillatory) schemes are employed in generalized coordinates to examine the effect of the wane frequency on the interference patterns. Non-reflecting boundary conditions, which is crustal for accurate computations of aeroacoustic problems, are used not to contaminate scattering fields by reflected waves at the outer boundary. Computed scattering fields show the circumferential acoustic modes generated by interacting between acoustic sources and scattered waves. At a lower frequency, the wave passes almost straight through the cylinder without Interacting with circular cylinder. Simulation results are presented and compared with the analytic solution. Computed RMS-pressure distribution on the cylinder wall is good agreement with exact solution.