• Proceedings of the KIEE Conference
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• 1996.07b
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• pp.804-807
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• 1996

This paper addresses the small-signal stability and control problems associated with a Static Var Compensator and its power system stabilizer. The major emphasis is on determination of suitable location for SVC arid stabilizer signal tuning through eigenvalues and frequency response techniques. To determinate of suitable location for SVC, this paper used transfer function residues. Adequate oscillation damping is achieved by the use of stabilizing signals, designed through frequency response techniques and added to SVC. The study system is Benchmark System.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.2
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• pp.146-150
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• 2009

An Intelligent active roll angle controller design algorithm is discussed. The detailed mathematical formulation and analysis are discussed, and then modeling and design method for active roll angle controller are presented. This paper proposes a design method based upon intelligent robust controller design algorithm to control actively roll angle for improving cornering performance problems. The intelligent robust controller is designed for steady speed driving vehicle system model with representation of steering angle and yaw angular velocity parameters for cornering stability. And the detailed formulation and analysis for the objective vehicle system are investigated.

• Transactions of the Society of Information Storage Systems
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• v.2 no.1
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• pp.56-64
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• 2006

This paper proposes a new and simple input prediction method for robust servo system. A robust tracking control system for optical disk drives to reject disk runout was recently proposed based on both Coprime Factorization(CF) and Zero Phase Error Tracking(ZPET) control. The CF control system can be designed simply and systematically. Moreover, this system has not only stability but also robustness to parameter uncertainties and disturbance rejection capability. Since optical disk tracking servo systems can detect only racking error, it was proposed that the reference input signal for ZPET could be estimated from tracking errors. In this paper, we propose a new control structure for the ZPET controller. It requires less memory than the previously proposed method for the reference signal generation. Therefore, it is very effective in runout control. Furthermore, this method can be applied to defective optical disk like surface defects on disk. Numerical simulation and experimental result show the proposed method effective.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.97-100
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• 2000

Deadbeat property is well established in digital control system design in time domain. But in continuous time system, deadbeat is impossible because of it's ripples between sampling points. But several researchers suggested delay elements. From some specifications such as Internal model stability, physical realizations and finite time settling, unknown polynomials with delay elements in error transfer functions can be calculated. For the application to the real system, robustness property can be added. In this paper, error transfer function is specified with 1 delay element and unkown coefficients are calculated from the specs. Especially, by varying settling time and the user-specified poles, a deadbeat controller with lower order is obtained.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.11
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• pp.50-57
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• 1997

In order to make unmanned machining systems with satisfactory performances, it is necessary to incorporate appropriate condition monitoring systems in the machining workstations to provide the required intelligence of the expert. This paper deals with condition monitoring for chatter, tool wear and breakage during turning operation. To develop economic sensing and identiffication methods for turning processes, sound pressure measurement and digital signal processing technique were proposed. We suppressed chatter by stability control methodology, which was studied through manipulation of spindle speeds regarding to chatter frequencies. It was shown that tool wear and fracture were identified and to be estimated by using the wear indices. The validity of the proposed system was confirmed through the large number of cutting tests.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.1
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• pp.15-21
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• 1995

Automatic monitoring of cutting process is one of the most important technologies for increasing the stability and the reliability of unmanned manufacturing system. In this study, the methods which use laser displacement signals and banded energy method are proposed to monitor chatter vibration in the turning process. From this method, the monitoring system of the chatter vibration was developed and investigated its practical possibility. As a result, it is shown by experiments that the chatter vibration can be detected accurately, and it can be widely used in most turning processes.

• Transactions of the Society of Information Storage Systems
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• v.3 no.3
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• pp.123-125
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• 2007

We report the readout stability improvement results of super-resolution near field structure (Super-RENS) writeonce read-many (WORM) disk at a blue laser optical system. (Laser wavelength 405nm, numerical aperture 0.85) By using diffusion barrier structure (GeSbTe sandwiched by GeN) and high transition temperature recording material ($BaTiO_3$), material diffusion of phase change layer and recording mark degradation were greatly improved during high power (Pr=2.0mW) readout process up to $1{\times}10^5$ times.

• Transactions of The Korea Fluid Power Systems Society
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• v.2 no.4
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• pp.7-13
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• 2005

This paper presents modeling and ostimator/controller design for the hydraulic system in Vehicle Stability Control(VSC) system. A nonlinear mathematical model of the VSC hydraulic system is proposed and its accuracy is experimentally verified. A brake pressure estimator is then designed based on the derived mathematical model of VSC hydraulic system. And a disturbance observer, which compensates the estimation error between the brake pressure and the computed brake pressure is also designed to enhance the accuracy of the estimator. The proposed controller has the form of a feedback controller and determines explicitly the on/off ratio of valves' driving PWM signals by means of making use of the simplified mathematical model in the VSC hydraulic system. The performance of the designed controller whose feedback signal is generated by the brake pressure estimator is validated through experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10a
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• pp.368-371
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• 1996

In this paper, a feedforward-plus-feedback control scheme is presented to prevent congestion in store-and-forward packet switching networks. The control scheme consists of two algorithms. Specifically, the input traffic adjustment algorithm employs a fairness policy such that the transmission rate of the input traffic is proportional to its offered rate. The control signal computation algorithms to ensure stability of the overall system in the robust sense and to ensure the desired transient behavior in the adaptive, with respect to variations of input traffic, are designed.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1981-1986
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• 2004

In this study, the basic motor control system had been investigated. The controller for this study consists of two main parts, a feedforward controller part and a feedback controller part. Each part will deals with different control problems. The feedback controller deals with robustness and stability, while the feedforward controller deals with response speed. The feedforward controller, used to solve the tracking control problem, is adaptable. To make such a tracking perfect, an adaptive law based on Feedback Error Learning (FEL) is designed so that the feedforward controller becomes an inverse system of the controlled plant. The novelty of FEL method lies in its use of feedback error as a teaching signal for learning the inverse model. The theory in $H^{\infty}$-Control is selected to be applied in the feedback part to guarantee the stability and solve the robust stabilization problems. The simulation of each individual part and the integrated one are taken to clarify the study.