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신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.12
This paper presents an active vibration control of cantilever beams under disturbances by a primary force. A direct velocity feedback control using a pair of PZT actuator and a velocity sensor is considered. Variation of the stability and performance with the locations of the sensor/actuator pair is investigated. It is found that the maximum gain varies with the locations of the sensor/actuator pair significantly. The maximum gain shows a symmetric distribution along the beam length with respect to the center point, although the boundary condition of the beam is unsymmetric. The control performance is affected by the location of the primary force as well as the location of the sensor/actuator pair. The active control system can more effectively reduce the vibration when the primary force is located close to the fixed boundary.
Filtered Velocity Feedback 제어기를 이용한 양단지지보의 음향파워 저감
신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.12
This paper investigates the filtered velocity feedback(FVF) controller for the reduction of the acoustic power radiated from a clamped beam. The instability problem due to the non-collocated sensor/actuator configuration when using PZT actuator should be sorted out. The roll-off property of the FVF controller at high frequency helps to alleviate the instability. The dynamics of clamped beams under forces and moments pair and the FVF controller are first formulated. The formulation of the sound radiated power is followed. The open loop transfer function(OLTF) synthesized with 100 modes is used to determine the stability of the control system. The control performance is finally estimated. The levels of the vibration and the sound radiated power are reduced in the wide bandbelow the tuning mode of the FVF controller.
Filtered Velocity Feedback 제어기를 이용한 평판 능동진동제어
신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.10
This paper reports a filtered velocity feedback(FVF) controller, which is an alternative to direct velocity feedback(DVFB) controller. The instability problems at high frequencies due to non-collocated sensor/actuator configuration with the DVFB can be alleviated by the proposed FVF controller. The FVF controller is designed to filter out the unstable high frequency response. The dynamics of a clamped plate under forces and moments and the FVF controllers are formulated. The stability of the control system and performance are investigated with the open loop transfer function(OLTF). It is found that the FVF controller has a higher gain margin than the corresponding DVFB controller owing to the rapid roll-off behavior at high frequencies. Although the gain margin cannot be fully utilized because of the enhancement at the high frequencies, the vibration at the modes lower than the tuning frequency is well controlled. This performance of the FVF controller is shown to be improved from that of the DVFB controller. It is, however, noted that the stability around the tuning frequency is very sensitive so that the enhancement in vibration level should be followed. The reduction performance at low frequencies using the FVF controller should be compromised with the enhancement in the vibration at high frequencies while designing the controller.
신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong),정상우(Jeong, Sang-Woo) 한국소음진동공학회 2010 한국소음진동공학회 논문집 Vol.20 No.12
This paper reports active control of clamped beams using acceleration feedback controllers (AF). The equations of motion of clamped beam under force and moment pairs were derived and the equations of AF controllers were formulated. The effect of the parameters - gain and damping ratio - of the AF controllers on the open loop transfer function was investigated mainly in terms of the system stability. Increasing the gain of the AF controller tuned at a mode, the magnitude of the open loop transfer function is increased at all frequencies. The increase of the damping ratio of the AF controller leads to decrease the magnitude of the open loop transfer function and modifies its phase characteristics to be more stable. Three AF controllers connected in parallel were then proposed. Each AF controller is tuned at the 2nd, 3rd and 4th modes, respectively. Their parameters were determined to remain the system to be stable based on the results of the parametric study. A significant reduction in vibration at the 3 modes can be obtained.
신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong),서희선(Seo, Hee-Seon) 한국소음진동공학회 2009 한국소음진동공학회 논문집 Vol.19 No.2
Dynamic response of a hull mounted sonar(HMS) to shocks transmitted through hull structures is analyzed and then the structural reliability of the sonars is evaluated. Finite element model of the hull mounted sonar is established and the transient responses to the shock is calculated using MSC.NASTRAN. According to BV043, the maximum allowable accelerations at the foundation of the sonar are converted from the shock spectra allowable for HMS. They are applied vertically and horizontally, respectively, using the large mass method. The structural reliability is evaluated by comparing the von-Mises stresses with the material yield stress. The drum for sensors shows a high reliability owing to mounts by which the shock waves from the base structure are well protected. However, the mounts between the base structure and the drum to mount sensors show a high stress intensity. The base structure also reveals a high stress intensity at the connection points to the hull.
Filtered Velocity Feedback 제어기를 이용한 양단지지보의 능동진동제어
신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong) 한국소음진동공학회 2011 한국소음진동공학회 논문집 Vol.21 No.5
This paper reports a filtered velocity feedback(FVF) controller, which is an alternative to direct velocity feedback(DVFB) controller. The instability problems due to high frequency response under DVFB can be alleviated by the suggested FVF controller. The FVF controller is designed to filter out the unstable high frequency response. The FVF controller and the dynamics of clamped beams under forces and moments are first formulated. The effects of the design parameters(cut-off frequency, gain, and damping ratio) on the stability and the performance are then investigated. The cut-off frequency should be selected not to affect the system stability. The magnitude of the open loop transfer function(OLTF) at the cut-off frequency should be small. As increasing the gain of the FVF controller, the magnitude of the OLTF is increased, so that the closed loop response can be reduced more. The enhancement of the OLTF at the cut-off frequency is reduced but the phase behavior around the cut-off frequency is distorted, as the damping ratio is increased. The control performance is finally estimated for the clamped beam. More than 10 dB reductions in velocity response can be achieved at the modal frequencies from the first to eighth modes.
모멘트쌍 액추에이터가 적용된 PPF에 의한 평판의 능동진동제어
신창주(Shin, Chang-Joo),홍진숙(Hong, Chin-Suk),정의봉(Jeong, Weui-Bong),유호영(You, Ho-Young) 한국소음진동공학회 2012 한국소음진동공학회 논문집 Vol.22 No.4
This paper reports the active vibration control of plates using a positive position feedback(PPF) controller with moment pair actuators. The equations of motion of the plates under a force and moment pairs are derived and the equations of PPF controllers are formulated. The numerical active control system is then achieved. The effect of the parameters - gain and damping ratio - of the PPF controllers on the open loop transfer function was investigated mainly in terms of the system stability. Increasing the gain of the PPF controller tuned at a mode, the magnitude of the open loop transfer function is increased at all frequencies without changing the phase behavior. The increase of the damping ratio of the PPF controller leads to decrease the magnitude of the open loop transfer function and to modify its phase characteristics, ie, system stability. Based on the behavior of the gain and the damping ratio of the controller, PPF controller for reduction of the plate vibration can be achieved. Two PPF controllers are designed with their connection in parallel to control the two modes simultaneously. Each PPF controller is tuned at the $1^{st}$ and $2^{nd}$ modes, respectively. Their parameters were determined to remain the system to be stable based on the results of the parametric study. A significant reduction in vibration at the tuned modes can be obtained.
스마트 부이로봇의 추진기 고장 감지 및 위치제어에 관한 연구
만동우(Dong-Woo Man),신창주(Chang Joo Shin),서정민(Jung-Min Seo),권오순(O-Soon Kwon) 한국산학기술학회 2023 한국산학기술학회논문지 Vol.24 No.5
항로표지 장비 중 많이 사용되고 있는 등부표는 대수심에 사용하기에는 제작 및 설치에 비용이 많이 발생하는 문제가 존재한다. 또한, 태풍에 의하여 앵커가 끊어져서 유실되는 문제들도 발생하고 있다. 이러한 문제를 해결하기 위해서 자가 앵커 및 추진기능을 가지는 스마트 부이로봇(SBR: Smart Buoy Robot)이 필요하다. 기존에 연구된 SBR은 고장 감지 기능의 부재로 인하여 고장 시 위치제어에 어려움이 존재하였다. 이러한 문제를 해결하기 위하여 본 논문에서는 전류센서를 이용하여 고장감지 기능 및 고장 발생 시 위치제어 방법을 제안하고 있다. 제안된 방법을 검증하기 위해 추진기 고장에 따른 외란 발생 시 위치제어를 수행하였다. 실험 결과는 추진기 고장 및 외란에도 정상 작동할 수 있으며 기능적으로도 효과적인 것으로 나타났다. 따라서 제안하는 방법은 위치제어에 효용성을 가지는 것을 알 수 있다. Light buoys are widely used navigational aids but have a problem in that they are expensive to manufacture and install for use in deep water. In addition, there are problems in that anchors break and are lost in typhoons. Therefore, a smart buoy robot (SBR) with self-anchor and propulsion functions is required. In previous studies, there was no failure detection function, so it was difficult to control the position when a failure occurred. To solve this problem, a fault detection function is proposed using a current sensor and a method for position control in the event of a fault. To verify the performance of the SBR, position control was performed under disturbance due to wave currents with propeller failure. Experimental results show that the SBR can operate under disturbances with propeller failure and is functionally effective. Therefore, the proposed controller is suitable for position control and has potential for actual applications.