• Korean Journal of Optics and Photonics
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• v.21 no.5
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• pp.206-213
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• 2010

We fabricated and characterized a compact endoscopic catheter for optical coherence tomography. The optical delay line (ODL), composed of a cylindrical piezoelectric transducer (PZT) and an optical fiber, was operated with a 1 kHz sinusoidal driving wave in the time-domain. When the ODL was driven with a sinusoidal wave function, the axial scanning speed was 6 m/s and the axial acquisition rate was 2000 line/s at a depth of about 3 mm. Endoscopic OCT images of a human finger and earhole were successfully obtained with an image rate of ten frames per second.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.665-666
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• 2006

In precision laser microfabrication, focusing is essential to acquire good machining precision and uniform machining quality. If it does not perform, laser machining cannot be realized. So, confocal scanning method with high depth resolution is used for focus detection technique. This paper is concerned with a procedure for design, analysis and performance test of an autofocus fine actuating stage, which is composed of flexure-hinge type lever mechanism and piezoelectric actuator. Through series of analytical design, the stage is simplified as a rigid bodies(lever and main body) and springs(flexure hinges). The simplified model was applied to determine the dimension of flexure hinges and lever. After structural analysis confirmed design requirement, an actual stage was made and verified through an experiment on the static and dynamic characteristics(maximum stroke and 1st natural frequency). The fabricated stage was satisfied with the design requirement.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.91-96
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• 2020

The 33-mode dielectric and piezoelectric properties of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3 piezoelectric single crystals were measured under large electric field and compressive stress. The phase transition from the low temperature rhombohedral to the high temperature tetragonal structure was observed in the range of 110~140℃, and the Curie temperature changing to the cubic structure was about 165℃. The polarization change according to the compressive stress and electric field was measured. Relative dielectric constant was calculated from the slope of the polarization curve applied to the electric field, and the calculated relative dielectric constant increased as the applied stress increased, and the relative dielectric constant decreased as the applied electric field increased. The strain according to the compressive stress and electric field change was measured, the piezoelectric constant was calculated from the slope of the curve, and the phase transition according to the application of pressure was confirmed. In the case of practical application as an underwater or medical ultrasonic actuator, it is necessary to properly design the magnitude of the compressive stress applied to the device and the DC bias in order to maintain linear driving.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.1
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• pp.45-50
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• 2006

This paper shows a new precision actuator of MUTM(miniature universal testing machine) for the testing of compression and tensile load on the MEMS materials and structures. The MUTM consists of a sample holder, an ultraprecision precision actuator(tranlation stage) and load sensor. The precision actuator has been developed for generating displacements with nanometer accuracy and a dynamic range of 1mm simultaneously. In this paper, it can be made by using the displacement property of bi-morph type PZT, which is able to extend the long range(stroke) according to cantilever size. However, it is not enough to be generated for compression and tensile load in miniature universal testing machine. Therefore, three dozen bi-morph type PZTs are used for generating the load. The load and displacement of the precision actuator are 35g and 0.4mm respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.136-139
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• 2006

In this paper we propose a small form factor actuator using an inclined motion guide for auto-focusing and zoom motions for mobile information devices. The novel structure using the inclined motion guide and a lens-supporting beam converts the circular motion by an ultrasonic motor into the linear motion of the optical lens. The proposed actuator has a simple structure to minimizing the mechanical tolerance, and the stroke is easy to modify by controlling the inclined angle. Experiments using a prototype verify the validity of the model as small form factor optical actuator.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.15 no.6 s.99
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• pp.667-673
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• 2005

This paper shows a method for design of the nano-positioning planar scanner used in the scanning probe microscope. The planar scanner is composed of flexure guides, piezoelectric actuators and feedback sensors. In the design of flexure guides, the Castigliano's theorem was used to find the stiffness of the guide. The motion amplifying mechanism was used in the piezoelectric actuator to achieve a large travel range. We found theoretically the travel range of the total system and verified using the commercial FEM(finite element method) program. The maximum travel range of the planar scanner is above than 140 $\mu$m. The 3 axis positioning capability was verified by the mode analysis using the FEM program.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.877-880
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• 2001

This paper presents the new linear motion device so called "inch-worm" which gets large displacement by incrementally summing small displacements of PZT actuators. Dynamics stiffness of inch-worm is generally low compared to its driving condition due to the requirement of inch-worm like small size and light weight. This low stiffness may degenerate the positional precision of inch-worm. An inch-worm is realized using three PZT actuators, a monolithic moving device and a guide way frame. Driving input signal is shaped to reduce the residual vibration of inch-worm by LQG controller and cycloid step input. The practical feasibility of inch-worm is also examined by running test.ning test.

• Proceedings of the KIEE Conference
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• 1998.07d
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• pp.1324-1326
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• 1998

To drive motor or heating machine, it needs the electric power system like the apparatus of inverter. This electric power system obviously comprises power switching devices and drivers to run them. And this system has the topology comprised one/many arm(s), - each arm has high side switching device and low side switching device. Transformer, photocoupler, and HVIC having functions of isolation and level shift which are important thing to drive high side switching device are used as component of drivers in conventional apparatus. Piezoelectric transformers are proposed in this paper, and applied to drive high side swiching device. Through experiments, the possiblities of driving high side switching device are presented and the problems are mooted concurrently. But, we also consider a counterplan for solving the mooted trouble issues.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1072-1075
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• 1997

To enhance the effective data transfer rate the multi-beam optical disk drive is presented. The Beam rotating actuator is necessary for putting multi-beam on more than one track. Ray tracing was also executed for real system set-up. The Beam Rotating Actuator is made up of piezoelectric material, high stiffness wire hinge and dove prism. The actuator has about 1kHz natural frequency and suitable and suitable operational range. The dynamic equation for the actuator is derived for the control of real system.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.3026-3032
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• 2000

To enhance the effective data transfer rate the multi-beam optical disk drive is presented. The Beam rotating actuator is necessary for putting multi-beam on more than one track. Ray tracing was also executed for real system set-up. The beam Rotating Actuator is made up of piezoelectric material, high stiffness wire hinge and dove prism. The actuator has about 1kHz natural frequency and suitable operational range. The dynamic equation for the actuator is derived for the control real system.