• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 추계학술대회논문초록집
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• pp.399.2-399
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• 2002

This paper concerns on a non-rotating single-DOF beam-active magnetic bearing(AMB) system subject to arbitrary shaped base motion. In such a system, it is desirable to retain the beam within the predetermined air-gap under foundation excitation. Motivated form this, an adaptive acceleration feedforward control is proposed to reduce the base motion response without deteriorating other feedback control performances. Experimental results demonstrate the effectiveness of the acceleration feedforward control.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.287-290
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• 1995

Recently H$_{\infty}$ control theory for nonlinear systems based on the Hamilton-Jacobi inequality has been developed. In this paper, we apply the state feedback controller solved via Riccati equation to a semi-active suspension model, two degree of freedom vehicle model, and show that it is effective for vibration control..

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 I
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• pp.471-475
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• 2001

This paper is concerned with the experiments on the dynamic characteristics and active vibration control of plate with piezoceramic sensors and actuators. The experimental frequency response plots can be used to verify the theoretical modeling. The active vibration control was achived by using a single-input single-output positive position feedback controller. Theoretical analysis will follow.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 추계학술대회논문집
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• pp.262-267
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• 2000

The flexural vibration of aluminum beams with active and passive constrained-layer damping has been investigated experimentally to design structure with maximum possible damping capacity. Piezoelectric film is used as sensor and piezoceramic as actuator for negative velocity feedback control. This paper shows the effectiveness of active constrained-layer damping treatment through experiment, and we have carried out an experiment to study effect of beam thickness.

• 소음진동
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• 제10권6호
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• pp.1083-1093
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• 2000

이 논문은 지능구조물의 실시간 적응진동제어를 위해 유전자 알고리즘을 이용하여 Positive Position Feedback(PPF) 제어기를 조정하는 것과 관련이 있다. 유전자 알고리즘은 최적변수를 찾는데 있어 국소 최소점이 아닌 전체적인 최적점을 찾을 수 있는 능력이 있다. PPF 제어기는 다른 진동모드에 영향을 주지 않으면서 특정 진동모드의 감쇠를 증가시킬 수 있는 장점을 가지고 있는 반면에 효과적인 진동제어를 위해서는 제어하고 자하는 진동모드의 고유진동수를 정확히 알아야하는 단점이 있다. 본 연구에서는 유전자 알고리즘을 이용하여 실시간으로 PPF 제어기가 필요로 하는 변수값을 추적할 수 있는 알고리즘을 개발하여 그 타당성을 실험으로 증명하였다. 실험결과는 PPF 제어기의 실시간 조정이 성공적으로 이루어져 진동제어가 효과적으로 이루어졌음을 보여주고 있다.

• 한국통신학회논문지
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• 제30권10A호
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• pp.906-911
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• 2005

본 논문에서는 제한된 피드백 정보를 사용하는 공간 다중화 기법에 사용될 수 있는 부 공간 방식 기반 preceding 기법을 제안한다. 제안된 preceding 기법은 수신기에서 다수의 공통 기저 집합(common basis sets)으로 부터 용량을 최대로 하는 기저들을 선택하고, 선택된 기저들은 feedback 정보를 통해 송신기에 전달되곤 송신기에서는 선택된 기저들로 이루처진 preceding 행렬을 구성한다. 선택된 기저들은 해당 기저들이 속한 기저 집합의 index에 대한 feedback 정보와 선택된 기저 집합에서 각 기저들의 선택 여부에 대한 feedback 정보를 통해 송신기로 feedback된다. 선택된 기저 집합 index는 송수신기가 약속한 공통 기저 집합 중에서 해당 MIMP 채널의 부 공간의 좌표(coordinate)에 가장 적합한 좌표를 나타내고, 해당 좌표에서 상당한 양의 에너지를 포함하는 기저들을 선택함으로써 적은 feedback 정보량으로 MIMO 채널을 묘사한다. 시뮬레이션을 통해 제안된 부 공간 방식 기반 preceding 기법이 적은 feedback 정보량을 사용하면서 폐루프 MIMO 용량 (closed-loop MIMO capacity)에 근접하는 용량을 제공함을 보인다.

• 한국전자파학회:학술대회논문집
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• 한국전자파학회 2003년도 종합학술발표회 논문집 Vol.13 No.1
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• pp.638-648
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• 2003

An active capacitance circuit is analyzed in depth and its application to active RF BPF with low noise figure is discussed. The characteristics of the active capacitance circuit made of FET[1] exhibits negative resistance and conventional capacitance, which is easily controlled. However, it is difficult to make the negative resistance adequate in the designated frequency range due to the lack of detailed analysis, which could make an active circuit unstable as the frequency is going higher or lower. In this paper, we analyzed the negative resistance characteristics of active capacitance circuits and also presented the method that the flatness of passband can be controlled. Finally we have designed a 4-stage active BPE, which results in bandwidth of 100 MHz, 0,04 dB insertion loss, 0.2 dB ripple, and noise figure of 2.4 dB at 1.75 GHz band.

• 제어로봇시스템학회논문지
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• 제7권11호
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• pp.891-895
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• 2001

An alternative inverse feedback structure for adaptive active control of periodic noise is introduced for systems with nonminimum phase cancellation path. To obtain the inverse model of the nonminimum phase cancellation path, the cancellation path model can be factorized into a minimum phase term and a maximum phase term. The maximum phase term containing unstable zeros makes the inverse model unstable. To avoid the instability, we alter the inverse model of the maximum phase system into an anti-causal FIR one. An LMS predictor estimates the future samples of the noise, which are necessary for causality of both anti-causal FIR approximation for the stable inverse of the maximum phase system and time-delay existing in the cancellation path. The proposed method has a faster convergence behavior and a better transient response than the conventional filtered-x LMS algorithms with the same internal model control structure since a filtered reference signal is not required. We compare the proposed methods with the conventional methods through simulation studies.

• International Journal of Aeronautical and Space Sciences
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• 제11권4호
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• pp.285-302
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• 2010

Active aeroelastic control is an emerging technology aimed at providing solutions to structural systems that under the action of aerodynamic loads are prone to instability and catastrophic failures, and to oscillations that can yield structural failure by fatigue. The purpose of the aeroelastic control among others is to alleviate and even suppress the vibrations appearing in the flight vehicle subcritical flight regimes, to expand its flight envelope by increasing the flutter speed, and to enhance the post-flutter behavior usually characterized by the presence of limit cycle oscillations. Recently adaptive and robust control strategies have demonstrated their superiority to classical feedback strategies. This review paper discusses the latest development on the topic by the authors. First, the available control techniques with focus on adaptive control schemes are reviewed, then the attention is focused on the advanced single-input and multi-input multi-output adaptive feedback control strategies developed for lifting surfaces operating at subsonic and supersonic flight speeds. A number of concepts involving various adaptive control methodologies, as well as results obtained with such controls are presented. Emphasis is placed on theoretical and numerical results obtained with the various control strategies.

• 한국소음진동공학회논문집
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• 제14권10호
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• pp.1007-1014
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• 2004

This paper presents a study of low frequencies volume velocity vibration control of a smart panel in order to reduce sound transmission. A distributed piezoelectric quadratically shaped polyvinylidene fluoride (PVDF) polymer film is used as a uniform force actuator and an array of $4\;{\times}\;4$ accelerometer is used as a volume velocity sensor for the implementation of a single-input single-output control system. The theoretical and experimental study of sensor-.actuator frequency response function shows that this sensor-actuator arrangement provides a required strictly positive real frequency response function below about 900 Hz. Direct velocity feedback could therefore be implemented with a limited gain which gives reductions of about 15 dB in vibration level and about 8 dB in acoustic power level at the (1,1) mode of the smart panel. It has been also shown that the shaping error of PVDF actuator could limit the stability and performance of the control system.