• 대한수학회보
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• 제51권4호
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• pp.933-942
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• 2014

We give a representation of the component of solutions with characteristic multiplier 1 in a periodic linear inhomogeneous continuous system. It follows from this representation that asymptotic behaviors of the component of solutions to the system and to its associated homogeneous system are quite different, though they are similar in the case where the characteristic multiplier is not 1. Moreover, the representation is applicable to linear discrete systems with constant coefficients.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.145-149
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• 1997

This paper describes a methodology for the development of models of discrete event system. The methodology is based on transformation of continuous state space into discrete one to homomorphically represent dynamics of continuous processes in discrete events. This paper proposes a formal structure which can coupled discrete event system models within a framework. The structure employs the discrete event specification formalism for the discrete event system models. The proposed formal structure has been applied to develop a discrete event specification model for the complex spectral density analysis of strip for urin analyzer system. For this, spectral density data of strip is partitioned into a set of Phases based on events identified through urine spectrophotometry. For each phase, a continuous system of the continuous model for the urine spectral density analysis has been simulated by programmed C++. To validate this model, first develop the discrets event specification model, then simulate the model in the DEVSIM++ environment. It has the similar simulation results for the data obtained from the continuous system simulation. The comparison shows that the discrete event specification model represents dynamics of the urine spectral density at each phase.

• 대한전기학회논문지:시스템및제어부문D
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• 제49권1호
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• pp.33-40
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• 2000

In this paper, an integrated method for the path planning and motion control of wheeled mobile robots using a hybrid system model and control is presented. The hybrid model including the continuous dynamics and discrete dynamics with the continuous and discrete state vector is derived for a two wheel driven mobile robot. The architecture of the hybrid control system for real time path planning and following is designed which has the 3-layered hierarchical structure : the discrete event system using the digital automata as the higher process, the continuous state system for the wheel velocity controls as the lower process, and the interface system as the interaction process between the continuous system as the low level and the discrete event system as the high level. The reference motion commands for autonomous navigation are generated by the abstracted motion in the discrete event system. The motion control tasks including the feasible path planning and autonomous motion control with various initial conditions are investigated as the applications by the simulation studies.

• 대한기계학회논문집
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• 제17권7호
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• pp.1678-1685
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• 1993

This paper considers a time delay control of noncolocated flexible mechanical systems in discrete time domain. A stability criterion suggested in the previous paper is,extended in the consideration of infinite mode property of flexible systems and finite control sampling frequency. Based on the stability criterion, the one step advanced discrete time derivative control is suggested, which can stabilize infinite number of modes of a flexible system. The sensitivity analysis shows the robustness of the one step advanced control to the system parameter uncertainties and time delay errors. Application to a simply supported beam verifies the extended stability criterion and the effectiveness of the one step advanced D-control.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1993년도 한국자동제어학술회의논문집(국내학술편); Seoul National University, Seoul; 20-22 Oct. 1993
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• pp.348-352
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• 1993

A hybrid system contains both continuous variables and discrete event components. This paper presents the new control architecture for hybrid systems, which consists of a conventional controller for the continuous-time variable of the system, a supervisor for discrete event components of the system, and an interface for link between the controller and the plant. The presented controller is suitable for the system operating at the different operating conditions or for system being changing the plant model by enabling and disabling discrete events. This paper shows that the presented controller is better than the conventional controller.

• 한국항만학회지
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• 제14권1호
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• pp.47-55
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• 2000

In order to cope with the changes of container terminal situation in these days, many simulation studies for container terminal have been accomplished. But previous simulation studies using simulation language have limitations in model representation and difficulties in modeling of large scaled container terminal system. To make these problems better, this paper addresses an object-oriented simulation of container terminal system using a DEVS formalism. The DEVS(Discrete Event System Specification) formalism, developed by Zeigler, supports specification of discrete event system in a hierarchical and modular manner. The formalism provides a mathematical basis for studying discrete event systems with better understood and sounder semantics. In a step of system modeling, a DEVS formalism aims at the exact system modeling that has a basis of semantics and utilizing the object-oriented manner can flexibly cope with the changes of system environment. In this study a model is developed and verified through the simulation of some alternatives.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1414-1417
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• 2003

In this paper, sliding mode controller for discrete-time nonlinear systems with uncertainties and disturbances are proposed. The concept of time-delay control (TDC) which consists of estimating the uncertain dynamics of the system through past observations of the system response is used. The proposed controller guarantees that the closed-loop system states are globally uniformly ultimately bounded (GUUB). It is also shown that the closed-loop system states are globally uniformly asymptotically stable (GUAS) if uncertainties are constant.

• 정보보호학회논문지
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• 제9권4호
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• pp.37-48
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• 1999

현대암호방식은 종래의 선형 대수와 수리이론을 적용한 암호통신을 벗어난 유사 잡음성을 띠는 카오스 신호를 이용한 암호통신을 적용해 오고 있다,[1-2] 본 논문은 1차 permutation 알고 리즘을 이용 하여 변환된 정보를 2차 이산 카오스 변환 함수를 이용해 암호화하는 광영상 암호시스템을 제안하여UT 다. 제안된 시스템은 키수열 발생기의 출력을 통해 영상정보를 permutation 하는 알고리즘 을 설계하였고 이에 대한 검정을 수행하였다. 또한 본 논문에서는 permutation 알고리즘을 통해 제한적인 카오스 함수 의 적용시 발생하는 문제점을 해결하고 비도를 증가시킴으로써 광영상 암호시스템에 적용 시 그 타당성 을 검정하였다. Current encryption methods have been applied to secure communication using discrete chaotic system whose output is a noise-like signal which differs from the conventional encryption methods that employ algebra and number theory[1-2] We propose an optical encryption method that transforms the primary pattern into the image pattern of discrete chaotic function first a primary pattern is encoded using permutation algorithm, In the proposed system we suggest the permutation algorithm using the output of key steam generator and its security level is analyzed. In this paper we worked out problem of the application about few discrete chaos function through a permutation algorithm and enhanced the security level. Experimental results with image signal demonstrate the proper of the implemented optical encryption system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.994-998
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• 2005

A new control method, called a simple model matching, has been recently developed by the author. This is very simple and be applied for linear and nonlinear discrete time systems with/without time lag. Based on this formulation, identification is examined in this paper using an interconnected neural network with the EBP-EWLS learning algorithm. With this result, a control method is also presented for a nonlinear discrete time system.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제53권7호
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• pp.444-451
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• 2004

Conventional magnetic levitation systems could show unsatisfactory performance under air-gap disturbance due to rail irregularities. In this paper, we propose a feedback control system with discrete Kalman filter for air-gap disturbance attenuation. It is shown that excellent system performance can be obtained with the use of discrete Kalman filter, and that results from experiments agree well with those of simulations.