• Journal of Power System Engineering
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• v.7 no.4
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• pp.38-43
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• 2003

This paper proposes an optimum design problem of structural and control systems. taking a 3-D truss structure as an example. The structure is supposed to be subjected to initial static loads and time-varying disturbances. The structure is controlled by a state feedback $H_{\infty}$ controller to suppress the effect of the disturbances. The design variables are the cross sectional areas of truss members. The structural objective function is the structural weight. As the control objective, we consider two types of performance indices. The first function represents the effect of the initial loads. The second one is the norm of the feedback gain. These objective functions are in conflict with each other. Then, first, two control objective functions are transformed into one control objective by the weighting method. Next, the structural objective is treated as the constraint. By introducing the second control objective which considers the magnitude of the feedback gain, we can per limn the design which is robust in modeling errors.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.505-509
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• 2002

The looper control of hot strip finishing mill is one of the most important control item In hot strip rolling mill process. Loopers are placed between finishing mill stands and control the mass flow of the two stands. Another important action of the looper is to control the strip tension which influences on the width of the strip. So it is very important to control both the looper angle and the strip tension simultaneously but the looper angle and the strip tension are strongly interacted by each other. The gain scheduling is to break the control design process into two steps. First, one designs local linear controllers based on linerizations of the nonlinear system at several different operating conditions. Second, a global nonlinear controller for the nonlinear system is obtained by interpolating.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2004.04a
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• pp.241-246
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• 2004

This paper proposed trajectory tracking control of mobile robot. Trajectory tracking control scheme are real coding genetic-algorithm and back-propergation algorithm. Control scheme ability experience proposed simulation. Stable tracking control problem of mobile robots have been studied in recent years. These studios have guaranteed stability of controller, but the performance of transient state has not been guaranteed. In some situations, constant gain controller shows overshoots and oscillations. So we introduce better control scheme using Real coding Genetic Algorithm(RCGA) and neural network. Using RCGA, we can find proper gains in several situations and these gains are generalized by neural network. The generalization power of neural network will give proper gain in untrained situation. Performance of proposed controller will verify numerical simulations and the results show better performance than constant gain controller.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.6
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• pp.592-600
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• 2010

The problem of motion control for AUV (Autonomous Underwater Vehicles) is addressed. The utilization of such robotic vehicles has gained an increasing importance in many marine activities. In this paper the objective is to describe how to design and apply FGS (Fuzzy Gain Scheduling) PD (Proportional Derivative) controller for an AUV (Autonomous Underwater Vehicle) to control the yaw and depth of the vehicle by keeping the path of the navigation to a desired point, and/or changing the path according to a set point.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.111.1-111
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• 2001

In this paper, a robust speed control is proposed for Permanent Magnet Synchronous Motor system. PMSM without reduction gear has been widely used in high performance application such as robots and machine tools. It is well known that the control performance of the PMSM is very sensitive to load disturbance and system parameter variation. The idea of the proposed speed controller based on combination of sliding mode control with fuzzy gain scheduling. The sliding mode controller leads to fast system dynamics of slight sensitivity to the load disturbance and system parameter variations, the fuzzy gain scheduling mechanism reduces the chattering phenomenon. The simulation results have proved that the proposed control scheme provides a robust control performance under load disturbance and system parameter variation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.41-45
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• 1997

To design a control system, it is a elementary point that the stability of the system should be guaranteed. Also, the phase of the system plays an important role for its frequence performance. In this paper, we present two stability criterion of repetitive control system with phase-lead and lag compensator. First, the stability criterion for the servo control system with phase-lead and lag compensator is shown by using small-gain theorem. Second, for the repetitive control system with the compensator, the stability criterion, also, is determined by using small-gain theorem. Two stability criterions show the same results that the stability depends on a coefficient of the phase-lead and lag compensator under some condition in servo control system and repetitive control system.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.12
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• pp.1065-1070
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• 2003

We present a power control with variable state feedback gain (VFPC) to improve outage convergence rate of distributed constrained power control. The variable state feedback gain includes the information of the desired SIR changes and must be a decreasing sequence for the convergence. The proof of the convergence is given. The proposed algorithm can improve the outage convergence rate and SIR (Signal to Interference Ratio) response at transient as well as at steady state. The simulation results are given to demonstrate the feasibility of the proposed scheme.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2001.06a
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• pp.121-124
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• 2001

In industrial actual control system, PID controller has been used with its high delicate control system in position control system. PID controller has simple structure and superior ability in several characteristics. When the response of system is changed by delay time, variable load , disturbances and external environment, control gain of PID controller must be readjusted on the system dynamic characteristics. Therefore, a control ability of PID controller is degraded when th control gain is inappropriately determined. When the response characteristic of system is changed under a condition, control gain of PID controller must be changed adaptively to be a waited response of system. In this paper an adaptive-tuning type PID controller is constructed by self-recurrent Neural Network(SRNN). applying back-propagation(BP) algorithm. Form the result of computer simulation in the proposed controller, its usefulness is verified.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.917-922
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• 2004

As the tasks of robots become more diverse, some complicated tasks have come to require force and position hybrid control. A compliant device can be used to control force and position simultaneously by separating the twist of the robot's end effector from the twist of compliance and freedom by using stiffness mapping of the compliant device. The development of a fuzzy gain scheduling scheme of control for a robot with a compliant device is described in this paper. Fuzzy rules and reasoning are performed on-line to determine the gain of twists based on wrench error and twist error and twist of compliance and twist of freedom ratio. Simulation results demonstrate that better control performance can be achieved in comparison with constant gain control.

• Korean Journal of Poultry Science
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• v.28 no.1
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• pp.61-67
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• 2001

Two experiments were conducted to evaluate the dietary supplemental fruit extract(Bio-plus) on performance and intestinal microflora of broiler chicks. Seven treatments were allocated into control, 0.05, 0.10, 0.20, 0.10, 0.20, 0.40, 0.80, 1.60% with four replications for five weeks, in both experiments. Diets contained 21.5% CP, 3, 100 kcal/kg ME for the rest two weeks. Weight gain, feed intake, feed conversion ratio(FCR) were weekly measured. Birds were sacrificed to examine the E. coli and Salmonella from cecum and ileum at the end of experiment. In experiment 1, Weight gain of Bio plus treatments tended to increase compared to that of control, but was not consistency between them. Chicks fed Bio-plus showed significantly lower feed conversion ratio(FCR) than control(P〈0.05). In experiment 2, Weight gain of Bio plus treatments was significantly different from control(P〈0.05) for starting period and linearly increased upto 0.80% for the rest of two weeks, but was not significantly different. Feed intake of chicks fed Bio-plus tended to be higher than control. Bio-plus treatments was not statistically different FCR from control. ND titer showed no significance, but tended to be higher in Bio-plus treatments than control. The number of ileum salmonella was significantly decreased in Bio-plus treatments compared to that of control in expt 2 (P〈0.05). Total yeast and Lactobacillus spp. of illeum tended to increase in expt 1 and were significantly higher in expt 2 than control(P〈0.05). The results of these experiment indicated that dietary Bio-plus supplements increased weight gain, the number of ileum yeast and Lactobacillus spp. of broiler chicks.