• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 추계학술대회논문집
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• pp.915-918
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• 2006

This paper presents an active vibration control of a 1-DOF system using a hybrid mount which consists of elastic rubber and electromagnetic actuator. After identifying stiffness, damping properties of the elastic rubber and electromagnetic element, a mechanical model of the hybrid mount is established. The mount model is then incorporated into the 1-DOF system and the governing equation of motion is obtained in a state space. A sliding mode controller is designed in order to actively attenuate the vibration of the system control responses such as acceleration and transmitted force of the 1 -DOF system are presented in time domain.

• Journal of Mechanical Science and Technology
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• 제15권10호
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• pp.1356-1368
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• 2001

In this paper, the model reference adaptive control (MRAC) of a flexible structure is investigated. Any mechanically flexible structure is inherently distributed parameter in nature, so that its dynamics are described by a partial, rather than ordinary, differential equation. The MRAC problem is formulated as an initial value problem of coupled partial and ordinary differential equations in weak form. The well-posedness of the initial value problem is proved. The control law is derived by using the Lyapunov redesign method on an infinite dimensional filbert space. Uniform asymptotic stability of the closed loop system is established, and asymptotic tracking, i. e., convergence of the state-error to zero, is obtained. With an additional persistence of excitation condition for the reference model, parameter-error convergence to zero is also shown. Numerical simulations are provided.

• 한국소음진동공학회논문집
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• 제17권5호
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• pp.391-397
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• 2007

This paper presents active vibration control using a hybrid mount which consists of rubber element and the piezostack actuator. After identifying stiffness and damping properties of the rubber element and piezoelectric elements, a mechanical model of the hybrid mount is established. The mount model is then incorporated with the vibration system, and the governing equation of motion is obtained in a state space. A sliding mode controller and LQG controller are designed in order to actively attenuate the vibration of the system subjected to various frequencies and small magnitude excitations. Control responses such as acceleration and force transmission through the hybrid mount are evaluated by computer simulation.

• 한국소음진동공학회논문집
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• 제17권7호
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• pp.617-623
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• 2007

This paper presents an active vibration control of a dynamic system using hybrid mount which consists of elastic rubber-piezostack actuator and elastic rubber-electromagnetic actuator, respectively. After identifying stiffness, damping properties of the elastic rubber, PZT actuator and electromagnetic element, a mathematical model of the hybrid mount is established. The mount model is then incorporated into the dynamic system and the governing equation of motion is obtained in a state space. A sliding mode controller is designed in order to actively attenuate the vibration of the system. Control responses such as acceleration and transmitted force of the dynamic system are experimentally evaluated and presented in time and frequency domains.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 춘계학술대회논문집
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• pp.1131-1136
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• 2007

This paper presents an active vibration control of a 1-DOF system using hybrid mount which consists of elastic rubber and PZT(piezostack) actuator and elastic rubber and electromagnetic actuator, respectively After identifying stiffness, damping properties of the elastic rubber, PZT actuator and electromagnetic element, a mathematical model of the hybrid mount is established. The mount model is then incorporated into the 1-DOF system and the governing equation of motion is obtained in a state space. A sliding mode controller is designed in order to actively attenuate the vibration of the system. Control responses such as acceleration and transmitted force of the 1-DOF system are experimentally evaluated and presented in time and frequency domains.

• Tribology and Lubricants
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• 제24권1호
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• pp.34-43
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• 2008

In this paper, an actively controlled aerostatic bearing is studied to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled aerostatic bearing is composed of aerostatic bearings, non-contact type of displacement sensors, piezoelectric actuators and controllers. The cylindrical capacitance sensor (CCS) is used as the displacement sensor. The reason for using CCS instead of the commercial gap sensor is that it can give us the pure error motion of the spindle because it removes the roundness error or the geometric errors in the spindle. The controller is designed by the state space equation and quadratic optimal control theory. The characteristic data of the actively controlled aerostatic bearing system in the frequency domain are presented and the stiffness and damping coefficients of the bearing are mentioned. This paper shows the possibility to reduce the motion error up to 6000 rpm.

• Structural Engineering and Mechanics
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• 제13권1호
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• pp.91-101
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• 2002

During the last several years, research activity on non-tubular bonded joints has concentrated on the effects of normal stress, bending moments and shear. Nevertheless, in certain situations, the structure may be subjected to twisting moments, so that the evaluation of its dynamic behaviour to torsional vibrations becomes of great importance even though evaluations of such loading conditions is entirely lacking in the literature. The aim of this article is to show that torsional natural frequencies of the non-tubular joint can be evaluated by determining the roots of a determinantal equation, derived by taking advantage of some analytical results obtained in a previous paper dealing with the analysis of the state of stress in the adhesive. Numerical results related to clamped-free and clamped-clamped joints complete the article.

• 제어로봇시스템학회논문지
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• 제18권4호
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• pp.314-320
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• 2012

This paper proposes a new robust motion deblurring filter using the inertial sensor measurements for strapdown image IR applications. With taking the PSF measurement error into account, the motion blurred image is modeled by the linear uncertain state space equation with the noise corrupted measurement matrix and the stochastic parameter uncertainty. This motivates us to solve the motion deblurring problem based on the recently developed robust least squares estimation theory. In order to suppress the ringing effect on the deblurred image, the robust least squares estimator is slightly modified by adoping the ridge-regression concept. Through the computer simulations using the actual IR scenes, it is demonstrated that the proposed algorithm shows superior and reliable motion deblurring performance even in the presence of time-varying motion artifact.

• 천문학회지
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• 제47권6호
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• pp.215-218
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• 2014

One-dimensional (1-D) microlens parallaxes can be combined with heliocentric lens-source relative proper motion measurements to derive the lens mass and distance, as suggested by Ghosh et al. (2004). Here I present the first mathematical anlysis of this procedure, which I show can be represented as a quadratic equation. Hence, it is formally subject to a two-fold degeneracy. I show that this degeneracy can be broken in many cases using the relatively crude 2-D parallax information that is often available for microlensing events. I also develop an explicit formula for the region of parameter space where it is more difficult to break this degeneracy. Although no mass/distance measurements have yet been made using this technique, it is likely to become quite common over the next decade.

• 한국소음진동공학회논문집
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• 제13권7호
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• pp.524-531
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• 2003

This paper presents an active vibration control of a flexible beam structure using a hybrid mount which consists of elastic rubber and Piezoelectric material. After identifying stiffness and damping properties of the rubber and piezoelectric elements, a mechanical model of the hybrid mount is established. The mount model is then Incorporated into the beam structure, and the governing equation of motion is obtained in a state space. A sliding mode controller is designed in order to actively attenuate the vibration of the beam structure subjected to high frequency and small magnitude excitations. The controller is experimentally realized and control responses such as acceleration of the beam structure and force transmission through the hybrid mount are evaluated. In addition. a comparative work is done between the passive and hybrid mount systems.