• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1998.04a
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• pp.678-683
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• 1998

Combustion instability by thermoacoustic feedback incite strong low frequency noise and vibration which damage the system and provoke the environmental problems. Therefore, it is necessary to control the thermoacoustic oscillation. In the way of controlling the instability, active control method using adaptive algorithm is applied. In this study, active noise control method using anti-sound technique is selected, whose principle is cancelling the noise with the addition of opposite phase sound. At first, simulation is performed to confirm the stability of controller, and after that control of combustion instability is carried out to get cancellation of 20-30dB SPL.

• 제어로봇시스템학회:학술대회논문집
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• 1995.10a
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• pp.43-46
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• 1995

Adaptive algorithms based on gradient adaptation have been extensively investigated and successfully jointed with active noise/vibration control applications. The Filtered-X LMS algorithm became one of the basic feedforward algorithms in such applications, but still is not fully understood. The error path model effect on the Filtered-X LMS algorithm has been under the investigation and some useful properties related stability has been discovered. We are interested in utilizing the fact that the model error caused by the way optimizing the error path model in a view point of convergence speed of Filtered-X LMS algorithm for pure tone noise suppression application without any performance loss at steady state.

• Journal of KSNVE
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• v.9 no.1
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• pp.33-41
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• 1999

This paper presents a method of actively controlling the interior noise by a trim panel with hybrid feedforward-feedback control loop. The control technique is designed to minimize the vibration of panel whose motion is limited to that of a piston (out-of-plane motion). The hybrid controller consists of an adaptive feedforward controller in conjunction with a linear quadratic Gaussian (LQG) feedback controller. In order to maintain control performance of both persistent and transient disturbances, the feedback loop speeds up the adaptation rate of feedforward controller by improving damping capacity of secondary plant related with the adaptation rule. Numerical simulation and experimental result indicate that the hybrid controller is a more effective method for reducing the vibration of the panel (and therefore the interior noise) compared to using feedforward controller.

• Wind and Structures
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• v.10 no.2
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• pp.209-214
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• 2007

• Smart Structures and Systems
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• v.20 no.1
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• pp.85-97
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• 2017

The aim of this research is to develop a new method to use magnetorheological (MR) damper for vibration control. It is a new way to achieve the MR damper response without the need to have detailed constant parameters estimations. The methodology adopted in designing the control structure in this work is based on the experimental results. In order to investigate and understand the behaviour of an MR damper, an experiment is first conducted. Force-displacement and force-velocity responses with varying current have been established to model the MR damper. The force for upward and downward motions of the damper piston is found to be increasing with current and velocity. In cyclic motion, which is the combination of upward and downward motions of the piston, the force with hysteresis behaviour is seen to be increasing with current. In addition, the energy dissipated is also found to be linear with current. A proportional-integral-derivative (PID) controller, based on the established characteristics for a quarter car suspension model, has been adapted in this study. A fuzzy rule based PID controller (F-PID) is opted to achieve better response for a varying frequency input. The outcome of this study can be used in the modelling of MR damper and applied to control engineering. Moreover, the identified behaviour can help in further development of the MR damper technology.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.3 s.192
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• pp.67-75
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• 2007

This paper deals with a problem of vibration suppression of a piezoelectric beam using a self-sensing algorithm. Two methods, which are PPF(positive position feedback) and SRF(strain rate feedback), are considered to suppress a residual vibration of a piezoelectric beam developed during the step positioning of a beam end point. A self-sensing algorithm treated here is basically a strain rate estimator of a beam movement and is to be used for the closed loop control. The efficacy of the proposed idea is evaluated through experiments.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.89-97
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• 2017

The tuned mass damper (TMD) system was first proposed as an efficient vibration control method for high-rise buildings, and multiple TMD (MTMD) system was then proposed for the purpose of improving the robust performance. Thereafter, the active TMD (ATMD) is proposed to improve the vibration control performance over the TMD and MTMD systems. However, this system may experience an system-instability problem in case of the actuator malfunction. In order to overcome such limitations of actuator malfunction causing the instability of the structural system, in this study, we investigate the feasibility of the multiple ATMD (MATMD) system that facilitates both advantages of the MTMD and ATMD. Numerical example demonstrates that, when the proposed system is designed to have the same capacity as the ATMD, it shows a similar control performance to the ATMD, but also has very good adaptive control performance against the emergency situations such as actuator failures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.11 s.104
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• pp.1303-1310
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• 2005

Stabilization error of target aiming systems mounted on moving vehicles is an important performance because the error directly affects hit Probability. In a heavy load targetaiming system, the disturbance torque comes from mass unbalance and linear acceleration is a main source of stabilization error. This study suggests an experimental design method of disturbance feedforward compensation control to improve the stabilization performance of heavy load target aiming systems. The filtered_x least square(FxLMS) algorithm is used to estimate the compensator coefficients adaptively. The proposed control is applied to a simple experimental set-up which simulates dynamic characteristics of a real target aiming system. The feasibility of the proposedtechnique is illustrated, along with results of experiments.

• Journal of KSNVE
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• v.2 no.2
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• pp.107-116
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• 1992

An adaptive signal processing technique is implemented for the active noise cancellation of the plane acoustic wave propagating in a duct. To avoid the instability caused by the acoustic feedback from the control speaker to the detect microphone, an off-line modeling of the acoustic feedback plant is done using the FIR filter. Auxiliary path required for the filtered-x LMS algorithm is modeled as well. Before going into the experiments, a simulation is carried out under the same conditions with experiments. The simulation shows that the longer the length of the adaptive filter is, the better the results are achieved. Experiments have been carried out at lower audio frequency range (50 - 400Hz), and the results are in good agreements with those of simulation study. As a results of this adaptive noise control, around 50dB is reduced for a pure tone noise, and for a bandlimited noise with the bandwidth of 316Hz, a maximum of 30dB noise reduction is attained.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.6
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• pp.94-101
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• 1994

About vibration model of Six-degrees-of-freedom(DOF), in mass load, examined results for knowing dynamic interference and response variation is as follows; In case of putting mass load upon the object, experimented results on two-degrees-of-freedom of the translation-1 direction and the rotation-1 direction at open-loop-control system, about 0.19 arcsed in input of the translation-$0.1{\mu}m$ and $0.022{\mu}m$ on input of the rotation-0.5 arcsec, the justicse of motion equation is acknowledged as confirming the appearance of the interference-$0.022{\mu}m$. In establishing calculation of transformation matrix by using analogue circuit, as simulating results that used incomplete differentiation, interference is $1.7{\times}10^{-3}$ arcsec on input of the translation-$0.1{\mu}m$ and $1.4{\times}10^{4}{\mu}m$ on input of the rotation-0.5 arcsec in open-loop-control system. Also it is $4.2{\times}10^{-4}$ arcsec on input of the translation-$0.1{\mu}m$ and $5.6{\times}10^{-5}{\mu}m$ on input of the rotation-0.5 arcesc in closed-loop-control system. As closed-loop-control system is better than open-loop-control system, equivalent accordance is confirmed on original response. Finally, fundamental validity of this theory is acknowledged.