• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1058-1059
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• 2015

최근 건축 구조물 설계에 있어서 외부 또는 내부로부터 발생될 수 있는 미지의 진동에 대하여 대책을 수립하여 구조물을 설계하고 있다. 뿐만 아니라 기타 제조업 분야에 있어서 정밀할 가공이 필요한 특수한 기계 가공기에 있어서 내부 또는 외부에서 발생될 수 있는 진동을 감안하여 시스템을 구성하고 있다. 이러한 구조물 및 기계시스템에 대하여 진동을 억제할 수 있는 진동 억제 알고리즘에 관해서는 많이 연구되고 있다. 본 논문에서는 구조물 및 기계시스템에서 발생될 수 있는 미지의 외란을 제거하기 위하여 내부모델제어(IMC)를 기반으로 수정된 적응 알고리즘을 매트랩 시뮬링크(matlab simulink)를 통하여 제어성능을 제시하고자 한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.1069-1070
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• 2015

본 논문은 일반적이 가진 시스템의 설계에 있어서 입력에 대한 추종과 비주기적인 외란이 발생하였을 때 주어진 입력을 추종하는 성능과 인가된 외란에 강인성을 가지도록 시스템을 설계하여야 한다. 이러한 제어기 설계에 가장 많이 이용되는 제어기가 PID 제어기이다. 본 논문에서는 일반적으로 널리 사용되고 있는 PID 제어기와 본 논문에서 비교하고자 하는 지적-PID(intelligent PID control) 제어기에 관하여 비교하였다. 이러한 제어기의 성능 검증을 통하여 가진기 시뮬레이터의 주 제어기로 사용하고자 한다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.11a
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• pp.443-448
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• 2000

In this paper, we propose a novel adaptive feedforward controller for periodic disturbance and noise cancellation, with a frequency tracking capability. It can be added to an existing feedback control system without altering the original closed-loop characteristics, which is based on adaptive algorithm. We introduce novel algorithm "Constrained AFC(adaptive feedforward controller) algorithm" that increase the convergence region regardless of the delay in the closed loop system. In the algorithms, coefficients of the controller are adapted using the residuals of constrained structure which are defined in such a way that the coefficients become time invariant. The proposed algorithm not only estimate the magnitude and phase of the tonal disturbance and noise but also track the frequency of the tone, which changes in quasi-static manner. The frequency tracking algorithm uses the instantaneous frequency approach based on Hilbert transform. A number of computer simulations have been carried out in order to demonstrate the effectiveness of proposed method under various conditions.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.127-128
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• 2008

전력계통 구성의 복잡함에 따라 보다 다양한 기능이 요구되는 디지털 보호 계전기는 구성 모듈이 점점 다양해지고, 상호 복합적으로 설계된다. 그러한 결과로 개발 시, 공인 인증된 디지털 보호 계전기의 외란에 대한 신뢰성은 예상치 못한 오류 등으로 인하여 신뢰를 상실하는 경우가 있고, 최악의 경우 오동작을 유발하여 전체 전력 계통의 정전을 초래할 수 있다. 특히 디지털 보호 계전기의 시스템 이상 감시에만 그치던 자기 감시 기능은 반복되는 잘못된 이상 감지 판단으로 관리자 및 실무자의 계통 보호에 대한 신뢰의 혼동을 가져올 수 있으며, 일반적인 자기 감시 주기인 $1{\sim}2$초는 그 순환 주기 시간이 너무 길어서 제대로 된 시스템 감시를 행하지 못할 수 있다. 물론 고속의 자기 감시가 필요한 부분은 특별히 존재하지 않지만, 이는 오동작 시 전체 시스템에 미치는 영향을 고려하면, 고속 감시 항목을 미리 지정하여 자기 감시의 신뢰도를 높이는 것도 매우 중요하다. 그렇지만 일반적으로 그 주기를 고속으로 매우 짧게 가져간다면 전체적인 시스템에 무리한 부담을 유발하여 기본 기능에 대한 안정성을 악화시킬 수 있다. 그러나 가장 위험한 현상은 자기 감시 실패 시 디지털 보호 계전기 뿐 아니라 전체 계통에 막대한 피해를 유발하는 것이다. 본 논문에서는 이러한 경우 오동작을 사전에 예방할 수 있는 추가 상시 감시 Tool을 제시한다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.6
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• pp.1036-1041
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• 2008

Periodic disturbance is practically occurred in several engineering applications, especially in data storage systems. However, recently addressed controls for such problem were mostly dealt with its deterministic nature, which is rarely practical in real-time implementation. We present an adaptive control approach for DC motor systems with periodic stochastic disturbance whose frequency and magnitude are both random variables. We establish adaptive state feedback control which is linearly composed of nominal and corrective control parameter matrices. The former is derived from a nominal system model voiding disturbance and the latter is constructed from a disturbed system model by using Lyapunov stability theory. We carry out computer simulation to evaluate the proposed control methodology and compare to the recently addressed control method to demonstrate its superiority.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.2
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• pp.153-163
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• 2004

The control objective in hard disk drives is to move head as fast as possible to target track and position the head over the center of target track in the presence of external disturbances. The external shock or disk clamping error in manufacturing process causes the disk center to deviate from the disk rotation center. The disk shift acts on the control system as disturbance and degrades severely the performance of disk drives. In this paper, we present a new controller that compensates for the periodic disturbances very fast. The disturbance compensator is arranged in parallel with the state feedback controller. To avoid the interference with the state feedback controller, the compensator creates compensation signal without the feedback of system output until steady state. The pulse type controller is included additionally for improving the transient performance due to initial state. Finally, in order to demonstrate the superior performance of the proposed compensator. we present some experimental results using a commercially available disk drive.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.8
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• pp.898-906
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• 1999

A control structure is introduced for the purpose of rejecting periodic (or repetitive) disturbances on a tracking system. The objective of the proposed structure is to drive the output of the system to the reference input that will result in perfect following without any changing the inner configuration of the system. The structure includes an adaptation block which learns the dynamics of the periodic disturbance and forces the interferences, caused by disturbances, on the output of the system to be reduced. Since the control structure acquires the dynamics of the disturbance by on-line adaptation, it is possible to generate control signals that reject any slowly varying time-periodic disturbance provided that its amplitude is bounded. The artificial neural network is adopted as the adaptation block. The adaptation is done at an on-line process. For this , the real-time recurrent learning (RTRL) algoritnm is applied to the training of the artificial neural network.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.7
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• pp.800-807
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• 1999

A Periodic disturbance canceller is proposed to compensate for the periodic disturbance due to cutting process in a CNC machining center. The periodic disturbance canceller estimates the Periodic disturbance without phase delay. This is achieved by using linear phase low-pass filter and frequency response reciprocal filter of plant at the frequency of the periodic disturbance. This method is implemented in the position control system of the CNC machining center with general disturbance compensators in order to compensate for both the frictional force and the periodic disturbance. The experimental results are described to show its effectiveness.

• Transactions of the Society of Information Storage Systems
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• v.3 no.4
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• pp.167-172
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• 2007

The recently-developed off-line learning control approaches for the rejection of periodic disturbances utilize the specific property that the learning system tends to oscillate in steady state. Unfortunately, the prior works have not clarified how closely the learning system should approach the steady state to achieve the rejection of periodic disturbances to satisfactory level. In this paper, we address this issue extensively for the class of linear systems. We also attempt to remove the effect of other aperiodic disturbances on the rejection of the periodic disturbances effectively. In fact, the proposed learning control algorithm can provide very fast convergence performance in the presence of aperiodic disturbance. The effectiveness and practicality of our work is demonstrated through mathematical performance analysis as well as various simulation results.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2309-2311
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• 1998

The attitude control of a double inverted pendulum with a periodical disturbance at link top is dealt in this paper. The proposed system is consisted of the double inverted pendulum and a disturbance link. The lower link is hinged on the plate to free for rotation in the vertical plane. The upper link is connected to the lower link through a DC motor. The DC motor is used to control the posture of the pendulum by adjusting the position of the upper link. The periodical disturbance can be generated by the additional link attached at the end of link 2 through another DC motor, which is the modeling of a posture for a biped supporting with one leg. The motor for the joint simulates the knee joint(or hip joint) and the disturbance for the legs moving in air. The algorithm for controlling a proposed inverted pendulum is consisted of a state feedback control and a fuzzy logic controller. The fuzzy controller keeps the center of gravity of the biped within the specified range through the nonlinear feedback compensator. The state feedback control takes over the role to maintain a desired posture regardless the disturbance at the link top. In these case, the change of the angle and COG of an upper link is compensated with on-line. Simulations with a mathematical model are conducted to show the validity of the proposed controller.