• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.5
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• pp.442-449
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• 2003

This paper discusses how to generate the reference compensation voltages in Dynamic Voltage Restorers (DVR) by use of PQR instantaneous power theory. Sensed three-phase terminal voltages are transformed to PQR coordinates without time delay. Since the reference voltage in PQR coordinates is a single dc value, the voltage controller for DVRs is simple and easy to design. Proposed control method can be implemented by feedforward controllers or by feedback controllers. This paper verified the theory by a feedforward controller of a DVR with simulation and experiment.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.73-80
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• 2002

이 논문은 MIMO 능동 자기 베어링 시스템에 있어서의 병진 및 회전(기울기)운동을 하는 횡축형 강체 로터의 동적 거동을 모델링하고, 로터 양 끝단의 간섭효과를 고려한 제어방법을 제안한다. 제어기는 DSP 보드를 이용하였으며, 설계된 제어기의 타당성을 시뮬레이션 및 실험을 통하여 검증하였다.

• Journal of the Korean Institute of Intelligent Systems
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• v.8 no.6
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• pp.37-47
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• 1998

This paper proposes a controller design method using the evolutionary computation algorithm and the fuzzy logic to control the wafer temperature in rapid thermal processing. First, we design the feedforward static controller to provide the control powers of the lamps for the given steady state temperature. Second, the feedforward dynamic controller is designed for the additional control powers to achieve a given transient response. These feedforward controllers are implemented by using the fuzzy logic to act as a global nonlinear controller over a wide range of operating points. The parameters of these controllers are optimized by using the evolutionary computation algorithm so that it can be used when the mathematical model is not available. In addition, the feedback error controller is introduced to compensate the feedforward controllers when there exist disturbances and modeling errors. The gain of feedback error controller is also obtained by the evolutionary computation algorithm. Through simulations, we verify the proposed control system can give a satisfactory performance.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.10
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• pp.52-63
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• 1998

In this paper, several improvements to a copy network proposed previously for multicast packet switching are described. The improvements provide a solution to some problems inherent in multicasting. The input fairness problem caused by overf low is solved by a dynamic starting point decider(DSD), which can calculate running sums of copy requests starting from any input port. The starting point is changed adaptively in every time slot based on both the fill level of the input buffers in current time slot and the overflow situations of the previous time slot. Using the fill level of the conventional network. The DSD also provides the function of regulating overall copy requests according to the amount of input traffics. This is an essential function in improving overall throughputs of the copy networks. The throughput of a multicast switch can be improved substantially if partial service of copy request is implemented when overflow occurs. Call-splitting can also be implemented by the DSD in a straightforward manner. The hardware for the DSD is derived with the objective of simple architectures for the high speed operation. Simulation study of the copy network under various traffic conditions is presented to evaluate its performance.

• Journal of IKEEE
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• v.9 no.1 s.16
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• pp.72-78
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• 2005

This paper describes the design of a robust output-feedback controller for a single-input single-output nonlinear dynamical system with a full relative degree. While all the previous research works on the output-feedback control are based on dynamic observers, a new state estimator which uses the past values of the measurable system output is proposed. We name it backward-difference state estimator since the derivatives of the output are estimated simply by backward difference of the present and past values of the output. The disturbance generated due to the error between the estimated and real state variables is compensated using an additional robustifying control law whose gain is tuned adaptively. Overall control system guarantees that the tracking error is asymptotically convergent and that all signals involved are uniformly bounded. Theoretical results are illustrated through a simulation example of inverted pendulum.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.3
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• pp.67-73
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• 2002

This paper presents a sliding mode observer and Controller far the state estimation and the dynamic stabilization of the magnetic levitation systems. The proposed striding mode observer is constructed by means of Lyapunov stability theorem to decrease the observer error, and the sliding rode controller is designed by a linear combination of the equivalent and nonlinear control input for the estimated states. The feasibilities of the suggested design method are illustrated with the simulation results.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.3
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• pp.240-248
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• 1999

This paper presents the application of fuzzy algorithm for speed control of Switched Reluctance Motor. SRM has a h highly nonlinear control characteristic and operates in saturation to maximize the motor torque. A systematic approach t to the modeling of highly nonlinear SRM drive system which includes the fuzzy controller with coarse control and fine C control is presented. PelfOlmance analysis of SRM dJive is reported for a wide range of operating conditions through s speed variation and load perturbation dynamics. The pelfOlmance indices of SRM drive system operating with fuzzy 1 logic controller are compared with the conventional controller to highlight the merits. The expel1mental results are p presented to confilm the validity of proposed fuzzy 10밍c controller.

• ICROS
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• v.6 no.5
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• pp.54-63
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• 2000

본 논문에서는 모델 불확정성을 가진 이산사건시스템의 강인 관리제어이론에 대해 알아본다. 지금까지 연구된 불확정성 이산사건시스템은 크게 두 부류로 구분된다. 첫째는 다중 모델의 집합으로 표현되는 불확정성 시스템으로서 제어 대상이 되는 시스템의 동적 특성이 몇 가지의 가능한 이산사건 모델들의 집합으로 기술되는 시스템이다. 두 번째는 비결정성 시스템으로서 시스템의 한 상태에서 하나의 동일 사건발생에 의해 천이되는 상태가 두가지 이상이 존재하여 상태천이에 있어 불확정성이 존재하는 시스템이다. 본 논문에서는 두가지 형태의 불확정성 이산사건 시스템들에 대한 강인 관리제어기 설계문제에 대해 살펴보고, 강인 관리 제어 이론에 대한 최근의 연구동향과 발전 방향에 대해 소개한다.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.642-648
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• 2008

A lot of researches on the redundant manipulators have been focused mainly on the minimization of joint torques. However, it is well-known that the most dynamic control algorithms using local joint torque minimization cause huge torques which can not be implemented by practical motor drivers. A new control algorithm which reduces considerably such a huge-required-torque problem is proposed in this paper. It adapts fuzzy logic and genetic algorithm to the conventional local joint torque minimization algorithm. The proposed algorithm is applied to a 3-DOF redundant planar robot. Simulation results show that the proposed algorithm works well.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.328-341
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• 2017

In the control actuator system of a launch vehicle based on thrust vectoring, the interaction between electro-mechanical position servo and inertial load are combined with the dynamic characteristics of the flexible vehicle support to generate synthetic resonance. This occurred resonance is fed back to the attitude control system and can influence stability of launch vehicle. In this study, we proposed a simulation model to analyze synthetic resonance of electro-mechanical actuation system for thrust vector control and explained the results of simulation and test using dynamic force feedback control which improves dynamic characteristics of servo actuation system by reducing synthetic resonance.