• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.2
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• pp.418-426
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• 1995

A bubble-powered microactuator is designed conceptually. And the actuation mechanism due to bubble growth and collapse is studied numerically and analytically. In this analysis, it is estimated that the time lag for bubble formation on micro line heater, the duration of the bubble growth and collapse and the pressure change in actuator due to the bubble evolution. Based on these calculations, the actuator control scheme is visualized. This actuator may be applicable to the system which needs to pump liquid correctly and regularly.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.9
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• pp.2272-2283
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• 1994

In scanning tunneling microscopy, the piezoelectric actuator is popuilarly used in stacked type as it can provide remarkable positioning resolution and stiffness. The actuator, however, exhibits a considerable amount of hystereic nonlinearity, resulting in losses of overall measuring accuracy when a linear model is used for its control and calibration, In this study, a nonlinear model is proposed for predicting the precise relationship between the input connand voltage and the output displacement of the actuator itself, cross-coupled electrical behaviours of the driving circuit with the actuator, and mechanical characteristics of the driven components of the actuator. Finally experimental results prove that the nonlinear model enhances the measuring of scanning tunneling microscopy by an order ten in comparison with a conventional linear model.

• Journal of Mechanical Science and Technology
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• v.19 no.2
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• pp.664-673
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• 2005

The heat transfer characteristics of rarefied flows in a micro-actuator are studied numerically. The effect of Knudsen number (Kn) on the heat transfer of the micro-actuator flows is also examined. The Kn based on gas density and characteristic dimension is varied from near-continuum to highly rarefied conditions. Direct simulation Monte Carlo calculations have been performed to estimate the performance of the micro-actuator. The results show that the magnitude of the temperature jump at the wall increases with Kn. Also, the heat transfer to the isothermal wall is found to increase significantly with Kn.

• The KSFM Journal of Fluid Machinery
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• v.19 no.1
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• pp.31-36
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• 2016

Hydraulic actuator is a primary component of the hydraulic valve systems. In this study, the thrust performance of hydraulic actuator was studied with different values of viscosity of hydraulic oil and rod diameter. Numerical analysis was performed using the commercial CFD code, ANSYS with 2-way FSI(Fluid-Structure Interaction) method and $k-{\varepsilon}$ turbulent model. Results show that increase in viscosity of hydraulic oil reduces the thrust of hydraulic actuator. In order to satisfy the output required of the actuator, it is necessary to compensate for the operating pressure. The results of pressure, velocity and thrust efficiency distributions in the hydraulic actuator were graphically depicted.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1988-1991
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• 2005

A micro fluid actuator driven by electromagnetic force at MEMS(Micro Electro Mechanical System) level has been designed. The operation of the actuator was simulated in three steps. First, fluid flow analysis has been performed to determine the actuator load. With the load, dynamic behavior of the actuator structure has been analysed. Finally, fluid-structure interaction analysis has been performed to predict the performance of the actuator. To avoid excessive amount of computation, axisymmetric and plane strain 2-D models were used.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.203-208
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• 2001

In this paper, a novel dual-type positioning mechanism using a voice coil motor(VCM) and a piezoelectric actuator is proposed for optical disk drive or near-field recording type drive. The VCM is used for a coarse motion actuator and the piezoelectric actuator, "S" configuration deflection motion when voltage applied, is used for a fine motion actuator with self-sensing technique, which allows it to sense and actuate simultaneously in a closed loop frame work. When the VCM rotates and stops, a position feedback control algorithm is adopted to further control residu vibration. The performance of the control scheme is confirmed through simulations and experiments.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.4 s.235
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• pp.624-631
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• 2005

A note-book PC has become thinner in recent years, which requires the optical disc drives with small height and high memory capacity. Therefore the actuator of optical disc drives must be thinner and have disc tilt compensation function for high density memory. In this paper, the actuator with hybrid type is investigated for 3-axis ultra-slim actuator. A 3-axis ultra-slim actuator is designed by using the modal analysis of the actuator and the electromagnetic analysis of magnetic circuit to achieve dynamic characteristics. Also, magnetic force between tilt magnet and tilt yoke is investigated to and the influence on the DC sensitivity in the focus and track directions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.1
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• pp.263-270
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• 1995

The use of the shape memory alloy, Nitinol wire, is investigated as an actuator for enhancing the damping in structural vibration systems. The first-order mathematical model of the Nitinol wire is obtained from the experimental data for an actuator. Finite element method is utilized for the strain gage sensor model, which is installed at the root of cantilever beam. A simple system, cantilever beam, is built as a flexible structural system to implement a control law with the Nitinol wire actuator. The system model including sensor and actuator is derived, which agrees with the experimental results. The actuator dynamics is augmented with the system so as to design PI controller and the one of robust controllers, LQG/LTR controller, and the control laws are implemented experimentally. The experimental study shows the feasibility of utilizing the Nitinol wire as an actuator for the purpose of vibration control.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.8
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• pp.737-742
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• 2014

This paper reports a customized silver ink and its inkjet printing process on a cellulose electro-active paper (EAPap). To synthesize a silver ink, silver nanoparticle is synthesized from silver nitrate, polyvinylpyrrolidone and ethylene glycol, followed by adding a viscosifier, hydroxyethyl-cellulose solution, and a surfactant, diethylene glycol. The silver ink is used in an inkjet printer (Fujifilm Dimatix DMP-2800 series) to print silver electrodes on cellulose EAPap. After printing, the electrodes are heat treated at $200^{\circ}C$. The sintered electrodes show that the thickness of the electrodes linearly increases as the number of printing layers increases. The electrical resistivity of the printed electrodes is $23.5{\mu}{\Omega}-cm$. This customized ink can be used in inkjet printer to print complex electrode patterns on cellulose EAPap to fabricate flexible smart actuators, flexible electronics and sensors.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3186-3198
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• 1996

When a robot is to have contact with its enviornment, such as a medi-care robot, it would be advantageous for the robot to have a high compliance. For this reason, a robot having not only a flexible link but also an actuator with compliance, is desirable. This paper is concerned with the position and vibration control of 1 degree of freedom flexible robot using a pneumatic artificial muscle actuator. The dynamics of the manipulator assumed to be and Euler-Bernoulli beam are derived on the basis of the linear mathematical modle. Although this pneumatic artifical muscle actuator has many merits for the compliance robot, it is difficult to make an effective control scheme of this system because of ths nonlinearity and uncertainty on the dynamics of the actuator. By designing a controller using .mu.-synthesis, robust performance against measurement noise, various modeling uncertainties on the dynamics of the servo valve, actuator and mainpulator, is achieved. The effectiveness of the proposed control method is illustrated through simulations and experiments.