• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.7
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• pp.619-625
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• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair. because the sensor-actuator pair has strictly positive real (SPR) property In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a Point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB show robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a “skyhook” damper, hut the point sensor-distributed actuator pair with DVFB acts as a “skyhook” rotational damper pair.

• Smart Structures and Systems
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• v.1 no.3
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• pp.283-308
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• 2005

This paper features about the modeling and design of a fast output sampling feedback controller for a smart Timoshenko beam system for a SISO case by considering the first 3 vibratory modes. The beam structure is modeled in state space form using FEM technique and the Timoshenko beam theory by dividing the beam into 4 finite elements and placing the piezoelectric sensor/actuator at one location as a collocated pair, i.e., as surface mounted sensor/actuator, say, at FE position 2. State space models are developed for various aspect ratios by considering the shear effects and the axial displacements. The effects of changing the aspect ratio on the master structure is observed and the performance of the designed FOS controller on the beam system is evaluated for vibration control.

• Smart Structures and Systems
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• v.25 no.1
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• pp.37-45
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• 2020

This paper aims at enlightening the properties, computational and implementation issues related to Kalman filter based state estimation algorithms and sliding mode observers, by applying them for estimating the states of a smart structure system. The Kalman based estimators considered in this work are Kalman filter and information filter and, the sliding mode observers considered are Utkin observer and higher order sliding mode observer. A fourth order linear time invariant model of a piezo actuated beam is used in this work. This structure is embedded with four number of piezo patches, of which two act as sensors, one as disturbance actuator and the other as control actuator. The performance of the state estimation algorithms is evaluated through simulation, for the first two vibrating modes of the piezo actuated structure, when the structure is maintained at first mode and second mode resonance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.778-783
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• 2003

The problem considered in this paper is about the collocation of sensor and actuator for the active control of sound and vibration. It is well-known that a point collocated sensor-actuator pair offers an unconditional stability with very high performance when it is used with a direct velocity feedback (DVFB) control, because the pair has strictly positive real (SPR) property. In order to utilize this SPR characteristics, a matched piezoelectric sensor and actuator pair is considered, but this pair suffers from the in-plane motion coupling problem with the out-of$.$plane motion due to the piezo sensor and actuator interaction. This coupling phnomenon limits the stability and performance of the matched pair with DVFB control. As a new alternative, a point sensor and piezoelectric actuator pair is also considered, which provides SPR property in all frequency range except at the first resonance in very low frequency. This non-SPR resonance could be minimized by applying a phase lag compensator.

• Smart Structures and Systems
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• v.24 no.2
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• pp.183-191
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• 2019

A piezoelectric paper feeder actuator using Micro Virtual Roller (MVR) is proposed, designed, fabricated and tested. This actuator can drive a sheet of paper forward or backward without any mechanical parts, such as the costly and heavy rollers used in traditional paper feeders. In this paper feeder actuator, two vibrating stators which produce traveling waves are used to drive the paper. The vibrations of the stators are similar to those of piezoelectric motors and follow a similar procedure to move the paper. A feasibility study simulated the actuator in COMSOL Multiphysics Software. Traveling wave and elliptical trajectories were obtained and the dimensions of the stator were optimized using FEM so that the paper could move at top speed. Next, the eigenfrequencies of the actuator was determined. Experimental testing was done in order to validate the FEM results that revealed the relationships between speed and parameters such as frequency and voltage. Advantages of this new mechanism are the sharp decrease in power consumption and low maintenance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.05a
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• pp.320-323
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• 2011

The compact camera assembled into Smart phone is required to have higher resolution level in non AF state than existing handsets, and it is also requested to have higher degree of accuracy, more consistent repetitiveness, and faster auto focusing speed. Algorithm based on a mechanical position of the existing actuator has been discussed. Therefore, in this thesis I suggest an improved algorithm concerning the problem of unstable resolution level in non AF state and auto focusing speed.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.223-226
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• 2001

A SMA actuator fabricated in this paper generates the large force and it's structure is very simple. The SMA actuator was fabricated by small size with diameter of 4mm and length of 38mm and also it's actuations toward all the directions can be acquired because of three SMA springs which was fabricated with diameter of 1.2mm and 30 turns. We showed into applicability to smart catheter by analyzing accurately the dynamic characteristics such as heading angle, bending angle, force, displacement. For verifying control capacity of the fuzzy controller, we compared Fuzzy controller with PID controller by simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.130.3-130
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• 2001

A SMA actuator fabricated in this paper generates the large force and it´s structure is very simple. The SMA actuator was fabricated by small size with diameter of 9mm and length of 27mm and also it´s actuations toward all the directions can be acquired because of three springs which was fabricated with diameter of 2.4mm and 28 turns, We showed into applicability to smart catheter by analyzing accurately the dynamic characteristics such as heading angle, force, displacement.

• Journal of KSNVE
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• v.8 no.5
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• pp.832-840
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• 1998

Experimental studies on the adaptive vibration control of composite beams have been performed using a piezoelectric actuator and the neuro-controller. The variations in natural frequencies of the specimen and the actuation characteristics of the piezoelectric actuator according to the delamination in the bonding layer have been studied. In addition, the simulation of adaptive vibration control has been performed for the composite specimens with delaminated piezoelectric actuator using neuro-controller. The hardware for the adaptive vibration control experiment was prepared. A DSP(digital signal processor) has been used as a digital controller. Using neuro-controller, the adaptive vibration control experiment has been performed. The vibration control results using the neuro-controller show that the present neuro-controller has good performance and robustness with the system parameter variations.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.2411-2413
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• 2001

A SMA actuator fabricated in this paper generates the large force and it's structure is very simple. The SMA actuator was fabricated by small size with diameter of 9mm and length of 27mm and also it's actuations toward all the directions can be acquired because of three springs which was fabricated with diameter of 2.4mm and 28 turns. We showed into applicability to smart catheter by analysing accurately the dynamic characteristics such as heading angle, force, displacement.