• 대한전자공학회논문지TC
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• 제45권12호
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• pp.74-82
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• 2008

본 논문에서는 다중 체인구조를 이용한 P2P 기반 IPTV 시스템을 제안한다. 제안하는 시스템은 P2P 네트워크의 특징인 peer의 빈번한 가입과 탈퇴 상황에서 단순한 과정으로 네트워크를 재구성하는 장점이 있다. 인터넷과는 달리 ISP가 관리하는 IPTV 환경은 전송회선의 속도와 안정성이 일정수준으로 보장되어 있다. 따라서 IPTV 환경에서의 P2P 네트워크는 단순성 측면을 우선적으로 고려해야 한다. 기존에 제안되어있는 단일 체인구조는 단순성을 강조하였으나 같은 채널을 시청하는 peer의 개수가 증가하면 체인의 끝 부분에 연결되어 있는 peer는 상당한 delay가 발생한다. 제안하는 시스템은 이러한 delay 문제를 해결하기 위하여 체인을 여러 개의 레벨로 분리하고 각 레벨은 다시 span으로 나누었다. 레벨과 span으로 분리를 하였지만 기본적인 구조는 체인구조이므로 peer가 join 하거나 departure 할 경우에 단순한 네트워크의 재구성 과정을 제공한다. 수치적인 해석을 통해 본 논문에서 제안한 다중 체인구조를 이용한 P2P 시스템이 단일 체인구조 방식에 비해 delay 및 신뢰도 성능이 우수하다는 것을 보여준다.

• 대한전기학회논문지:시스템및제어부문D
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• 제51권7호
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• pp.294-301
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• 2002

A new dynamic scheduling algorithm is proposed for CAN-based real-time system in this paper. The proposed algorithm is extended from an existing EDS(Earliest Deadline Scheduling) approach having a solution to the priority inversion. Using the proposed algorithm, the available bandwidth of network media can be checked dynamically, and consequently arbitration delay causing the miss of deadline can be avoided. Also, non-real time messages can be processed with their bandwidth allocation. Full network utilization and real-time transmission feasibility can be achieved through the algorithm. To evaluate the performance of algorithm, two simulation tests are performed. The first one is transmission data measurement per minute for periodic messages and the second one is feasibility in the system with both periodic messages and non-real time message.

• Transactions on Control, Automation and Systems Engineering
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• 제2권3호
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• pp.163-168
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• 2000

The problems of mixed $H_2/H_{\infty}$ filtering design fer continuous and discrete time linear systems with time delay are investigated. The main purpose is to design a stable mixed $H_2/H_{\infty}$ filter which minimizes the H$_2$Performance measure satisfying a prescribed H$_{\infty}$ norm bound on the closed loop system in continuous-time case and discrete-time case, respectively. The sufficient conditions of existence of filter, the mixed $H_2/H_{\infty}$ filter design method, and the upper bound of performance measure are proposed by LMI(linear matrix inequality) techniques in terms of all finding variables. Also, we present optimization problems in order to get the optimal mixed $H_2/H_{\infty}$ filter in continuous and discrete time case, respectively.

• International Journal of Control, Automation, and Systems
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• 제2권4호
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• pp.501-508
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• 2004

A new method to solve a Lyapunov equation for a discrete delay system is proposed. Using this method, a Lyapunov equation can be solved from a simple linear equation and N-th power of a constant matrix, where N is the state delay. Combining a Lyapunov equation and frequency domain stability, a new stability condition is proposed for a discrete state delay system whose state delay is not exactly known but only known to lie in a certain interval.

• 한국정보처리학회논문지
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• 제4권11호
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• pp.2801-2811
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• 1997

본 논문에서는 화상회의 시스템에서 다양한 미디어의 동기화를 위해서 미디어 지연시간(delay time)의 편차를 분석하여 대기시간을 적용하여 동기화하는 방법을 제안한다. 또한 미디어 트래픽의 손실률과 대기시간을 이용하여 대기시간을 결정하는 데 중요한 외부변수의 값을 결정한다. 먼저 제안된 시스템은 회의를 시작하기 전에 더미 스트림을 발생시켜 지연지터의 편차를 구하여 네트워크 트래픽을 분석하여 미디어의 표현시간을 정의한다. 미디어 스트림이 표현되는 시간은 기준시간(basetime)＋논리 시간＋대기시간이 된다. 이 때 대기시간을 적절하게 늘이고 줄이기 위해서 대기시간 변경율과 표본단위를 이용하는데, 평가기준은 대기시간을 변경시키는 횟수, 평균 대기시간, 지연도착율, 평균 지연도착시간을 이용한다．

• 제어로봇시스템학회논문지
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• 제14권8호
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• pp.779-784
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• 2008

This paper presents Kalman filter based system modeling algorithm for autonomous robot systems. State of the robot system is measured using embedded sensor systems and then carried to a host computer via ubiquitous sensor network (USN). We settle a linear state-space motion equation for unknown robot system dynamics and modify a popular Kalman filter algorithm in deriving suitable parameter estimation mechanism. To represent time-delay nature due to network media in system modeling, we construct an augmented state-space model which is mainly composed of original state and estimated parameter vectors. We conduct real-time experiment to test our proposed estimation algorithm where speed state of the constructed robot is used as system observation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1997년도 한국자동제어학술회의논문집; 한국전력공사 서울연수원; 17-18 Oct. 1997
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• pp.69-72
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• 1997

A universal controller is designed using a DSP (digital signal processor). The design objectives of the system are to implement control algorithms that require a lot of calculations and to develop a convenient user-interface environment. To demonstrate the efficiency of the system, the time delay control algorithm is implemented for the 2 D.O.F.SCARA type robot and the experimental results are presented.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1997년도 전력전자학술대회 논문집
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• pp.336-340
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• 1997

This paper is a study about motor technic of motion and feedforward control in order to shape cutting control on the machine tool. The shape error caused by delay of the servo system in the direction of radius at the time of circular cutting is reduced by feedforward control, shape error generated by the position command delay is minimized by using the acceleration/deceleration time constant after the interpolation. The study was verified to optimization of motion control on experiments of a vertical machining center of the machine tool.

• Journal of applied mathematics & informatics
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• 제27권5_6호
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• pp.1097-1107
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• 2009

In this paper, three species stage-structured predator-prey model with time delayed and periodic constant impulsive perturbations of predator at fixed times is proposed and investigated. We show that the conditions for the global attractivity of prey(pest)-extinction periodic solution and permanence of the system. Our model exhibits a new modelling method which is applied to investigate impulsive delay differential equations. Our results give some reasonable suggestions for pest management.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.895-897
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• 1988

This paper is concerned with linear system containing time delay in model reference adaptive control. An algorithm is developed using Lyapunov second method and properties of strictly positive real function.