• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1332-1340
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• 1992

A novel approach based on a nonlinear compensator is prposed to prevent 'windup', which is caused by the saturation of the acutator and the integral action of the controller. The anti-windup compensator is located between the conventional linear controller, designed neglecting the saturation, and the actuator. It was proven based on the describing function method that, if the closed loop control systems are stable assuming no saturation, then there may exist a range of compensator gain which prevents any limit-cycle. The computer simulation results show that the compensator proposed in the manuscript can eliminate the limit cycle and improve the transient response.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.2
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• pp.46-56
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• 1999

A predictive controller is designed based upon stochastic methods for compensation time-delay effect on a system which has inherent time-delay caused by the spatial separation between controllers and actuators. The predictive controller estimates current outputs through linear prediction methods and probability functions utilizing previous outputs, and minimizes the malicious phenomena caused by the time-delay in precision control systems. To demonstrate effectiveness of this control methodology, we applied this algorithm for the control of a tele-operated DC servomotor. The experimental results show that this predictive controller is superior to the PID controller in terms of convergence-characteristics, and show that this controller expands the maximum allowable time-delay for a system maintaining the stability. Since the proposed predictor does not require models of plants - it requires only stochastic information for outputs --, it is a general scheme which can be applied for the control of systems which are difficult to model or the compensator of PID control.

• Journal of Ocean Engineering and Technology
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• v.9 no.2
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• pp.175-185
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• 1995

본 논문은 불확실한 환경에 접촉하는 매니플레이터의 강인 제어법을 제시하였다. 이 제어법은 고차수 보상기를 응용한 표적특성에 $H_{\infty}$ 강인제어 설계법을 적용하여 얻어졌다. 접촉중의 위치와 힘에 대한 강인 안정성과 강인 성능 조건을 유도하였다. 결과에 의하면, 위치제어기는 강인 안정성과 강인 성능 조건을 동시에 향상시킬 수 있으나, 힘 제어기는 그 둘 사이에 최적화가 요구되었다. 강인 성능 제어기를 얻기 위한 최적화 설계기법은 변형 해석 기법을 사용하였으며, 결과의 예를 제시하였다. 이 예에서는 힘제어기의 강인 성능이 설계될 수 있음을 보였다.

• 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.

• Journal of the Korean Professional Engineers Association
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• v.22 no.3
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• pp.14-20
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• 1989

전력수요의 급증에 따라 단위기의 용량 및 전력계통의 규모가 대형화되어 지속적인 안전운전이 계통운용의 최우선 과제가 되였으며, 신뢰도향상 및 계통간전력수급의 원활한 융통을 위하석 계통간의 연계는 물론 다계통간의 다중연계에 이어 국가간의 연계도 이루어지고 있다. 본고에서는 전력계통의 대형화 및 연계화 추세에 따라 계통 무효전력 조류의 신속한 조절과 속응전압조정의 필요성이 증대되어 그 응용이 확산되고 있는 Thyristor제어 정지형 무효전력 보상기(이하 SVC라 칭함)의 원리, 특성, 응용 및 계통에 미치는 효과에 대하여 고찰하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.7
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• pp.1307-1313
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• 1992

The end-point position control of a flexible manipulator is a non-minimum phase system. The PD feedback of the end-point position is not stable in contrast with that of the hub jangle. However, the system can be stabilized conditionally by the feedback of both the hub rate angle and the end-point position. Even in the non-minimum system, the LQG/LTR control law is more systmatic controller design method than the classical control law which uses a root-locus technique.

• Journal of the Institute of Convergence Signal Processing
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• v.3 no.1
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• pp.74-79
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• 2002

Many control techniques have been proposed in order to improve the control performance in discrete-time domain control system. In control system using these techniques, the response-characteristic of system is dependent on the gains of the controller. Specially, There is a need to readjust the gain of controller when the response of system is changed by disturbance or load fluctuation. In this paper, I-PD controller and pre-compensator are designed by multilayer neural network. The gains of I-PD controller and pre-compensator are adjusted automatically by back propagation algorithm when the response characteristic of system is changed under a condition. Applying this control technique to the position control system using a DC servo motor as a driver, the control performance of controller is verified by the results of experiment.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.163-167
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• 2014

To prove the vibration and speed error problems caused by the nonlinear friction characteristics and load variation of the hydraulic system, a PID speed controller and a load compensation controller for the hydraulic inverter-fed elevator are proposed. The load compensation controller is composed by the PI controller and the speed controller is composed by the PID controller. The P,I and D gains of the control parameters are obtained by the frequency response of system transfer function. The Effectiveness of the proposed controller are shown by experimental results, which the proposed controller yields robustness with load variations and stable and good speed and acceleration responses with less oscillations.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.304-305
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• 2015

본 논문에서는 국내 기존 제련 공장의 무효전력을 보상하기 위한 SVC(Static Var Compensator)의 구성과 제어기에 대하여 소개하고자 한다. 본 SVC는 제련 공장의 22.9kV 계통에 적용하는 보상장치로써 TCR(Thyristor controlled reactor), Air-core Reactor, 2,3,4,5차 고조파 필터, 제어반 등으로 구성된다. 이는 Hybrid SVC을 적용한 사례이다. 역율 제어와 전압 제어를 적용하여 전력 품질 확보를 기하고자 설계 되어졌으며 SVC의 용량 ${\pm}100MVar$가 적용되어졌다.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.118-120
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• 2009

본 논문에서는 직접 전력변환방식의 단상 sag/swell 보상기를 구현하였다. 제안된 보상기는 정현파 입력/ 출력 필터, 직렬연결 변압기와 dc 링크 커패시터부가 없는 단상 back-to-back PWM컨버터로 구성되어 있다. 이 보상기의 장점은 dc-link 진해 커패시터가 제거되어 전력회로부가 간단하게 구현되어 향상된 신뢰성 및 내구성을 확인 할 수 있으며 동시에 단상 전압 sag/swell을 보상하며 스위칭 손실을 줄이는 간단한 PWM 방법을 들 수 있다. 더구나, 제안된 방법은 일반적인 직접 전력변환방식에서 요구되어지는 복잡한 4-step 전류 방법이 필요 없는 간단한 전류제어방법을 채용할 수 있는 구조이며 제안된 보상기의 구조와 PWM 방법의 타당성을 프로토타입 하드웨어를 제작하여 실험결과로 보상기의 우수성을 확인하였다.