• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.2
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• pp.139-146
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• 2015

This paper presents the solution to model matching of switched asynchronous sequential machines by corrective control. We propose a model of switched asynchronous sequential machines, in which the system can have different dynamics of asynchronous machines governed by a pre-determined sequence of switching. The control objective is to derive a corrective control law so that the stable state behavior of the closed-loop system can match that of a prescribed model. A new skeleton matrix is defined to represent the reachability of the switched asynchronous machine, and a novel control scheme is presented that interweaves the switching signal and the corrective control procedure. A design algorithm for the proposed controller is illustrated in a case study.

• Journal of the Korea Computer Industry Society
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• v.6 no.3
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• pp.401-412
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• 2005

인터넷을 통한 정보 전달 방법은 Ethernet과 ATM, CAN과 같은 다양한 통신 전달 프로토콜 및 방법을 통해 이루어지고 있다. 현재 연구된 네트웍상의 시간 지연 현상에 대한 연구는 일부네트웍 모델을 바탕으로 연구되고 있으나 다양한 통신 환경 하에서 발생하는 시간 지연 현상에 대해 최적의 모델링 방법을 제시해 주고 있지 못하고 있다. 따라서 다양한 네트웍 환경에 적합하도록 인터넷기반 비동기 샘플치 시스템 모델에 대한 연구가 필요하다. 아울러 인터넷을 통해 구성된 폐루프 시스템은 기존 제어 시스템과 다른 동작 특성과 외란 특성을 가지므로 인터넷 환경에 적합하게 설계된 견실 제어 방법이 필요하다. 따라서 안정성이 극히 요구되는 각종 산업기기 등에 대한 웹기반 정밀 원격 제어를 원활히 수행하기 위해서는 웹 환경에 최적화된 강인 제어 이론 개발이 필요하다. 따라서, 본 논문에서는 원격지 플랜트에 대한 실시간 원격 제어를 안정적 및 효율적으로 수행하도록 인터넷상의 데이터 전송시 시간 지연 현상 분석 및 인터넷 기반 제어시스템의 전달 특성 분석하였다.

• The Journal of the Korea Contents Association
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• v.6 no.8
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• pp.1-7
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• 2006

In this paper, proposed the method to increase the battery life of the Wibro terminal by reducing its power consumption. The amount of power consumption was analysed. And as the results, it is shown that the suggested method can be reduced the power consumption. The performance of the proposed system, which control the number of pilot of symbol, analysed by the simulation. It is shown that the power consumption of the terminal can be reduced by the reduction of the CINR for the percentage of pilot per symbol, as 0.48dBm for 10% and 0.95dBm for 20%, which can be accomplished by changing the current system of having the fixed number of pilot.

• Journal of Advanced Navigation Technology
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• v.7 no.2
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• pp.191-198
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• 2003

In this paper, we analyze the performance of transmit diversity techniques which are the key technologies of the third generation mobile communication systems. Transmit diversity techniques adopted on the specification of 3GPP are classified into open-loop and closed-loop methods depending on the existence of feedback data. In WCDMA systems, the DPCH signal is space-time coded to provide a mobile station with diversity. Computer simulations shall be performed to analyze and compare their performance considering the effect of mobile speed, number of path, power control, and delay of feedback with the WCDMA slot format #13 for application to WCDMA systems.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.6
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• pp.15-24
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• 2000

This paper presents an output feedback robust H$\infty$ control problem for a class of uncertain nonlinear systems, which can be represented by an fuzzy dynamic model. The nonlinear system is represented by Takagi-Sugeno fuzzy model, and the control design is carried out on the basis of the fuzzy model. Using a single quadratic Lyapunov function, the globally exponential stability and disturance attenuation of the closed-loop fuzzy control system are discussed. Sufficient conditions for the existence of robust H$\infty$ controllers are given in terms of linear matrix inequalities(LMIs). Constructive algorithm for design of robust H$\infty$ controller is also developed. The resulting controller is nonlinear and automatically tuned based on fuzzy operation.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.173-181
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• 2014

This paper addresses the problem of model matching control for a class of systems modeled as input/output asynchronous sequential machines. Based on the feedback control scheme, we design a corrective controller that compensates the behavior of the closed-loop system so as to match a reference model. Whereas the former studies use state observers and the output burst for designing a controller, the present research needs neither the observer nor the output burst in controller design. We define the 'output equivalent machine' of the considered machine to describe the existence condition and the construction algorithm for the proposed controller. A case study is provided to show the operation of the proposed corrective controller.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.5
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• pp.13-21
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• 2000

In this paper, we investigate the performance improvement by applying flow control to LonWorks-based network systems which support various communication media together with interpretable class of systems. To this end, we introduce a circular queue at each node of industrial network systems usually operated in open loop. Then we utilize the feedback information of the number of data in a queue, the data arriving interval in a queue and channel error to make the overall industrial network system in closed loop. We verify the improved performance of the network systems in view of throughput and fairness measures via the experimental results conducted in several field situation.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.3
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• pp.15-21
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• 2009

In this paper, we consider the design problem of robust stabilization and robust guaranteed cost state feedback controller for discrete-time singular systems with parameter uncertainties by LMI(linear matrix inequality) approach without semi-definite condition and decomposition of system matrices. The objective of robust stabilization controller is to construct a state feedback controller such that the closed-loop system is regular, causal, and stable. In the case of robust guaranteed cost control, the optimal value of guaranteed cost and controller design method are presented on the basis of robust stabilization control technique. Finally, a numerical example is provided to show the validity of the design methods.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.12a
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• pp.205-208
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• 2000

In this paper, we'll show that an improved PDFF controller is obtained by substituting a feedforward compensator in the existing PDFF system with a dual-input describing function, and the controller has the ability of adjusting the bandwidth of a system as well as the phase margin simultaneously. The effectiveness of the proposed controller is confirmed by applying to the DC-motor position control system. As the results of simulation, we know that it is possible to design a controller by which the bandwidth of the closed system and its phase margin are easily adjusted.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.85-88
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• 2005

Space-time code is a good solution to get transmit diversity. During the last years a number of space-time block codes have been proposed for use in multiple transmit antenna systems. This code, however, was presented only for the special case of the certain numbers of transmit antennas and the certain modulation schemes. and designed under the assumption that the transmitter has no knowledge about the channel. In this work, on the other hand, we consider the case when the transmitter has partial, but not perfect knowledge about the channel. This system can have full diversity for arbitrary number of the transmit antennas with a little bits of feedback.