• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2545-2547
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• 2000

In this paper, a hybrid fuzzy controller using genetic algorithm based on parameter estimation mode to obtain optimal control parameter is presented. First, The control input for the system in the HFC is a convex combination of the FLC's output in transient state and PID's output in steady state by a fuzzy variable, namely, membership function of weighting coefficient. Second, genetic algorithms is presented to automatically improve the performance of hybrid fuzzy controller utilizing the conventional methods for finding PID parameters and estimation mode of scaling factor. The algorithms estimates automatically the optimal values of scaling factors, PID parameters and membership function parameters of fuzzy control rules according to the rate of change and limitation condition of control input. Computer simulations are conducted to evaluate the performance of proposed hybrid fuzzy controller. ITAE, overshoot and rising time are used as a performance index of controller.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.2684-2686
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• 2000

This paper describes a preliminary study on a modeling technique for control performance evaluation of asynchronous TMR(Triple Modular Redundancy) controller. Hybrid system modeling is applied to TMR controller performance evaluation and mixed logical dynamical system description is used to model the behavior of majority voter in the controller. Windup and bumpless transfer problems in redundancy controls are also mentioned.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.421-423
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• 1999

The function of the automatic train operation(ATO) system is to regulate the train ride comfort during start, acceleration and deceleration and execute operation of constant speed travelling and fixed point parking. The mathematical model for the train is presented by considering unknown disturbances which consist of start resistance, travelling resistance, slope resistance, curve resistance and so on. The speed control of ATO system is designed by considering the disturbances. The simulation is executed to verify the speed control performance and compare its performance with that of a PID-type ATO control system under the disturbances. Simulation results show that the control performance of gain scheduled control for ATO system is better than that of the conventional PID controller.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.6
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• pp.164-169
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• 2000

Recently, High accuracy and precision are required in various industrial field especially, semiconductor manufacturing apparatus, Ultra precision positioning apparatus, Information field and so on. Positioning technology is a very important one among them. As such technology has been rapidly developed, this field needs the positioning accuracy as high as submicron. It is expected that the accuracy of 10nm and 1nm is required in precision work and ultra precision work field, respectively by the beginning of 2000s. High speed and low vibration are also needed. This work deals with the design method and control system of Ultra precision positioning apparatus. Control performance and stability analysis were performed in advance by modeling and designing the controller with Simulink.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1249-1255
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• 2006

This paper presents a constant power control logic for perfect starting a microtubine in vehicle. Under extremely low temperature, performance of the start-up system is severely dropped than that of room temperature because of increasing of load of mechanical parts including engine core and drop of the lead-acid battery capacity. Unfortunately, performance drop of lead-acid battery makes severe problems that cause a malfunction of fuel and lubrication system and power fail of digital devices. So we propose the new start-up logic by constant output power control of lead-acid battery using PWM inverter controller for preventing above problems and keeping good performance of start-up system for microturbine. Also, we prove usefulness of new start-up logic through experimental results under $-32^{\circ}C$ ambient temperature.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.10
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• pp.571-578
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• 1999

Current waveform control of pulse MAG welding power source is studied so that welding of thin plates may obtain high speed and improved performance. In this paper, waveform control method is proposed, digital controller using DSP is able to control the current waveform precisely. High speed welding of thin plates using pulse MAG welding method is made possible. Performance test for 1.2mm thin plates is carried out, output waveform and welding performance is analyzed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.53 no.2
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• pp.51-57
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• 2004

Vector control schemes are used in inverter-fed induction motor drives to obtain high performance. Crucial to the success of the vector control scheme is the knowledge of the instantaneous position of the rotor flux. However, the position of the rotor flux change with temperature and magnetic saturation of the motor. This variation cause deterioration of both steady state and dynamic operation of the motor drives. Performance degradation is in the form of input-output torque nonlinearity and saturation of the motor. Analytic expressions are derived to evaluate the effects due to parameter sensitivity. Also, dynamic response is shown by speed command with the variation of stator and rotor resistance.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1732-1739
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• 2017

This paper presents a sensorless vector control algorithm of closed loop Gopinath flux observer to enhance the robustness at low speed by switching P/PI mode. Closed loop Gopinath flux observer has the problem in sensorless vector control of induction motor at low speed. This paper solves the problem using the characteristic function of closed loop Gopinath flux observer. P mode shows better performance than PI mode under the cut-off frequency of observer. But P mode always has a flux error due to DC offset, so this paper combines P mode and PI mode. This algorithm shows good performance over wide speed range. The performance has been confirmed through computer simulations using MATLAB SIMULINK and experiments.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.3 no.2
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• pp.5-10
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• 2004

In this paper, the hybrid-type current controller for inverter TIG systems was implemented and it was shown that the low-current pulse wave forms with high dynamic performance could be obtained. It is not sri easy to obtain the optimum gain tuning of PID controllers in digital PWM control methods. Hybrid control methods which uses automatic tuning techniques after adding fuzzy control methods to traditional PID controllers are chosen to improve the dynamic performance of PID controller's. To demonstrate the practical significance and dynamic performance improvement of the results, some simulation and experimental results are presented.

• The Journal of Engineering Research
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• v.6 no.2
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• pp.39-46
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• 2004

In this paper, we carry out a performance study related to the Broadband Network. For this network, it has been proposed to use the leaky bucket as a way of controlling congestion within the network. On the top of leaky bucket type rate based congestion control scheme for high speed networks, a user will typically operate an error control scheme for retransmitting lost and erroneous packets. We propose a performance model in order to study the interaction between a user's error control scheme and the leaky bucket congestion control scheme for high speed networks. Simulation results show that parameters such as the window size and the token generation rate in the leaky bucket are key factors affecting the end-to-end delay.