• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2014.10a
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• pp.670-672
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• 2014

In this study, we investigate active control of noise transmitted through a window of enclosures minimizing the acoustic power. To reduce noise of the enclosures, passive methods with absorbing material are generally used. The passive methods, however, are limited use due to the vantilation windows. In this case, these windows are path of noise leakage. Feedforward active noise control technology is applied to minimize the sound power from the enclosure. The feedforward controller is implemented with FIR filter based on the transfer functions calculated numerically. The controller reflects the delay due to FIR filter. The noise transmitted through the window is actively controlled, and the reduction of the power is obtained by 15dB.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.634-639
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• 2006

Active control method is applied to a flexible beam excited by a shock impulse in order to reduce the residual vibrations after the shock event. It is assumed that the shock input can be measured and is always occurred on the same point of the beam. If the system is well identified and the corresponding inverse system is designed reliably, it has shown that a very simple feed-forward active control method may be applied to suppress the residual vibrations without using error sensors and adaptive algorithm. Both numerical simulations and experimental results show a promising possibility of applying to a practical problem. Also, the performance of the method is examined by considering various practical aspects : shock duration, shock magnitude, and control point.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.733-738
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• 2012

This paper presents active noise control for the reduction of transmission noise passing through opening of enclosures. Enclosures are essential measure to protect noise propagation from operating machinery. Access openings of the enclosures are important path of noise leakage. First, we modeled and analyzed the noise characteristics passing through the openings of the enclosure generated by the operation of the machinery based on the finite element method. We then implemented a feedforward controller to actively control the acoustic power through the opening. Finally, we conducted optimization of placement of the reference sensors for several cases of the number of sensors. A good control performances were achieved using a minimum number of microphones arranged a optimal placement.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1996.10a
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• pp.319-322
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• 1996

Automatic gauge control algorithm in rolling process is composed of several functions. Among them feedforward control method is used to compensate irregularity of input strip thickness before rolling process. Since it's very difficult to get an explicit relation between the degree of irregularity of input strip and manipulated variables, approximate linear equation like straight line is used in real system. Furthermore parameters included in such static equation should be changed by characteristics of input strip and modified by roll states. Despite this problem, rolling process use variables in feedfroward controller as a constant. Therefore this problem increases the possibilities of irregularity of thickness control. This paper presents an algorithm which can properly infer present states of process and intelligently manipulate the parameter of feedforward controller.

• Journal of Advanced Marine Engineering and Technology
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• v.20 no.4
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• pp.11-19
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• 1996

Recently, fuzzy and neural network techniques have been successfully applied to control of complex and ill-defined system in a wide variety of areas, such as robot, water purification, automatic train operation system and automatic container crane operation system, etc. In this paper, we present a neuro-fuzzy controller which unifies both fuzzy logic and multi-layered feedforward neural networks. Fuzzy logic provides a means for converting linguistic control knowledge into control actions. On the other hand, feedforward neural networks provide salient features, such as learning and parallelism. In the proposed neuro-fuzzy controller, the parameters of membership functions in the antecedent part of fuzzy inference rules are identified by using the error backpropagation algorithm as a learning rule, while the coefficients of the linear combination of input variables in the consequent part are determined by using the least square estimation method. Finally, the effectiveness of the proposed controller is verified through computer simulation of an inverted pendulum system.

• 유공압시스템학회:학술대회논문집
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• 2010.06a
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• pp.81-85
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• 2010

This paper deals with the issue of motion control of a single rod cylinder-load system using simple adaptive control (SAC) method. Prior to controller design, the experiment of open-loop response has been performed. Based on it, design parameters of transfer function are obtained. The effect of parallel feedforward compensator has been investigated by computer simulation, suppressing the oscillatory motion. Through experiments it is conformed that the SAC method gives good tracking performance compared to the PD control method.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.397-400
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• 2001

This paper proposed a speed adaptive control system with load torque observer and feed-forward compensation using neural network for air compressor system driven an induction motor. The motor receive impact load change under the influence of piston movement of up and down, and so it difficult to obtain good speed control characteristics. With real-time adjusting control gain estimated in neural network, control characteristics of motor is improved. The validity of the proposed system is confirmed through the theoretical analysis and computer simulation.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.7
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• pp.1332-1339
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• 2010

This paper presents a large signal analysis of ring-type oscillators with feed forward and negative skewed delay scheme. The analysis yields the frequency increase factor due to two schemes. The large signal analysis is needed, because small signal model is limited to the initial stage of oscillation[1]. For verification of the frequency increase factor, simulation were done under the same conditions for the two different types of ring oscillators, i.e., with and without feed forward and negative skewed delay scheme. Simulation results are in good agreement with predictions based on analysis.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.272-274
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• 2005

본 논문은 PWM DC-DC 변환기의 입력 임피던스를 Middlebrook의 EET (Extra Element Theorem)를 사용하여 해석할 수 있는 방법을 제시하고, 이를 이용하여 실제로 전압 제어, 전류 제어 승압형 변환기에 대한 입력 임피던스를 해석하였다. 유도된 수식은 간략화, 근사화를 통하여 보드 선도 (Bode plot)화 하였고, 입력 임피던스 특성 및 전류 루프, 피드백/피드포워드 루프, 전압루프의 영향을 해석하였다. 또한 이론적 해석은 컴퓨터시뮬레이션 결과 및 실제 제작된 PWM DC-DC 변환기의 실험 결과로 비교, 검증하였다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.10-12
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• 2019

영구자석 동기 전동기는 높은 효율과 전력 밀도 등의 장점때문에 자동차나 엘리베이터 등 다양한 산업 분야에서 사용되고 있다. 영구자석 동기 전동기의 구동에는 여러가지 이유로 인해 고조파 토크 리플이 존재한다. 이러한 토크 리플은 속도 리플을 유발하여 소음이나 진동의 원인이 되며, 그 분포가 전동기의 구조나 운전점에 따라 변화하기 때문에 제어 성능에 매우 큰 영향을 준다. 본 연구에서는 영구자석 동기 전동기의 운전점에 따라 변화하는 토크 리플을 상쇄하기 위해 주입할 최적의 고조파 토크를 실시간으로 추적하는 방법을 제안한다. 제안된 방법에서는 속도 제어 중 토크 리플에 의해 발생하는 속도 리플을 적분하여 평가지표로 삼고, 속도 리플이 감소하는 방향으로 주입할 고조파 토크의 크기와 위상을 조정한다. 이 방법은 제정수 추출이나 회전자의 위치 별 토크 테이블 없이 운전 조건의 변화에 따라 토크 리플의 최적 보상점을 추적한다는 장점이 있다. 제안된 방법의 효과는 시뮬레이션을 통해 검증되었다.