• Journal of fish pathology
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• v.27 no.2
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• pp.99-105
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• 2014

Biosensors consist of biochemical recognition agents like antibodies immobilized on the surfaces of transducers that change the recognition into a measurable electronic signal. Here we report a piezoelectric immunosensor made to detect Vibrio vulnificus. A 9MHz AT-cut piezoelectric wafer attached with two gold electrodes of 5mm diameter was used as the transducer of the QCM biosensor with a reproducibility of ${\pm}0.1Hz$ in frequency response. We have tried different approaches to immobilize antibody on the sensor chip. Concerning the orientation of antibody for the best antigen binding capacity, the antibody was immobilized by specific binding to protein G or by cross-linking through hydrazine. In addition, protein G was cross-linked on glutaraldehyde activated immine layer (PEI) or EDC/NHS activated sulfide monolayer (MPA). PEI was found to be more effective to immobilize protein G following glutaraldehyde activation than MPA. However, hydrazine chip showed a better capability to immobilize more IgG than protein G chip and a higher sensitivity. The sensor system was able to detect V. vulnificus in dose dependent manner and was able to detect bacterial cells within 5 minutes by monitoring frequency shifts in real time. The detection limit can be improved by preincubation to enrich the bacterial cell number.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.6
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• pp.550-557
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• 2008

Delamination damage at a bolt hole in a composite stiffened panel was detected using a built-in piezoelectric active sensor array. Various signal processing techniques were used to detect an invisible small scale delamination around a fastener hole due to localized transverse loading. A built-in piezoelectric sensor array was used to generate diagnostic signals and to measure response signals. Then, the response signals were processed to extract damage-sensitive features. Damage indexes were calculated to estimate the severity and location of the damage from the features.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.744-749
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• 2005

In this paper, a lens actuator for mobile devices is proposed using stack type piezoelectric materials. In general, the deformation of PZT actuators is not enough for lens motion when the allowed voltage is applied. The small stroke problem can be solved by accumulating a lot of small displacements in high frequency. In this paper, a new inch-worm type model for focusing actuator is suggested based on the interaction of inertial and frictional forces. Theoretical analysis and simulation using ANSYS are performed to verify the feasibility of the inch-worm PZT actuator model. Various types of clamps are considered to determine the effect of frictional force on the motion, and appropriate clamp-actuator models are proposed. The proposed models are experimentally verified and the experimental results show high correspondence with theoretical and simulated values. The inch-worm type focusing actuator enable a large stroke with 7.79 mm/sec with 10kHz and 10V.

• Smart Structures and Systems
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• v.26 no.6
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• pp.735-751
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• 2020

Identification of structure parameters is crucial in Structural Health Monitoring (SHM) context for activities such as model validation, damage assessment and signal processing of structure response. In this paper, guided waves generated by piezoelectric transducers are used for in-situ and non-destructive structural parameter estimation based on Bayesian approach. As Bayesian approach needs iterative process, which is computationally expensive, this paper proposes a method in which an analytical model is selected and developed in order to decrease computational time and complexity of modeling. An experimental set-up is implemented to estimate three target elastic and geometrical parameters: Young's modulus, Poisson ratio and thickness of aluminum and steel plates. Experimental and simulated data are combined in a Bayesian framework for parameter identification. A significant accuracy is achieved regarding estimation of target parameters with maximum error of 8, 11 and 17 percent respectively. Moreover, the limitation of analytical model concerning boundary reflections is addressed and managed experimentally. Pulse excitation is selected as it can excite the structure in a wide frequency range contrary to conventional tone burst excitation. The results show that the proposed non-destructive method can be used in service for estimation of material and geometrical properties of structure in industrial applications.

• Composites Research
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• v.20 no.6
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• pp.21-27
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• 2007

Low-velocity impact damage in a composite stiffened panel was detected using built-in piezoelectric active sensor arrays. Using these piezoelectric active sensors, various diagnostic signals were generated to propagate Lamb waves through the structure and the responses were picked up to detect changes in the structure's vibration signature due to the damage. Three algorithms - ADI(Active Damage Interrogation), TD RMS (Time Domain Root Mean Square) and STFT (Short Time Fourier Transform) - were examined to express the features of the signal changes as one damage index. From damage detecting tests, two impact induced delaminations were detected and the location was estimated with the algorithms and diagnostic signals.

• Journal of KSNVE
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• v.7 no.1
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• pp.161-168
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• 1997

The present paper describes the vibration control experiment of composite plates with bonded piezoelectric sensor and actuator. The system is modeled as two degree-of-freedom system using modal coordinates and the system parameters are obtained from vibration tests. Kalman filter is adopted for extracting modal coordinates from sensor signal, and control algorithms applied to the system are Linear Quadratic Gaussian(LQG) control, Bang-Bang Control (BBC), Negative Velocity Feedback(NVF), Proportional Derivative Control(PDC). From observation of the spillover and control perfomance, it is concluded that a higher order control algorithm such as LQG rather than BBG, NVF, PDC is suitable for efficient simultaneous control of both bending and twisting modes of composite plates.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.9 no.6
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• pp.51-58
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• 2010

This paper suggests a control technique of the two axes precision stage. The stage is supported by four flexible spring hinges and driven by two piezoelectric actuators. The dynamic motion of the stage is analysed by the finite element method and identified by the frequency domain modeling technique based on the experimental data. The sliding mode control with integrator is applied to improve the tracking ability of the stage to the complex reference input signal. Experimental results demonstrate that the proposed modeling schemes and control algorithm can be used effectively for the two axes stage.

• Smart Structures and Systems
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• v.19 no.6
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• pp.615-624
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• 2017

This paper experimentally investigates the feasibility of harvesting vibration energy from whistles using piezoelectric materials. The end goal of this research is to generate sufficient power from the whistle to power a small radio transmitter to relay a basic signal - for example, a distress call. First, the paper discusses the current literature in energy harvesting from acoustic resonance. Next, the concept of an active whistle is presented. Next, results from energy harvesting experiments conducted on conventional and ultrasonic whistles undergoing human-actuation and actuation by a pressure-regulated air supply are presented. The maximum power density of the conventional whistle actuated by a human at 100 dB sound pressure level is $98.1{\mu}W/cm^3$.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.239-244
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• 2009

This paper suggests a precision positioning control technique of a precision positioning stage with coupling effects. The precision positioning stage is supported by four flexible spring hinges and driven by two piezoelectric actuators. The dynamic characteristics of the precision positioning stage is modeled and identified by the FEM analysis. The dynamic characteristics of the stage are also identified by the frequency domain modeling technique based on the experimental data. Reliability of two modeling methods is examined by comparing the numerically and experimentally produced responses of the stage. This paper proposes a sliding mode control technique with integrator to improve the tracking ability of the precision positioning stage to the complex input signal using. To demonstrate the effectiveness of the proposed modeling schemes and control algorithm, experiment validations are performed.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.7
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• pp.756-763
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• 2008

This paper presents an inchworm with three piezoelectric actuators. The dynamic stiffness of the inchworm is generally low compared to its driving condition, so mechanical vibration may degenerate the motion accuracy of the inchworm. The dynamic model of inchworm is identified by curve fitting technique based on the experimental frequency response function. For the precision motion control and low residual vibration of inchworm, driving input signal is designed by using cycloid step input and LQG control technique. Experimental result shows that proposed input shaping method is applicable effectively to the inchworm.