• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.5-8
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• 2005

In this paper, the electromechanical displacements of curved piezoelectric actuators composed of PZT ceramic and laminated composite materials are calculated based on high performance computing technology and the optimal configuration of composite curved actuator is examined. To accurately predict the local pre-stress in the device due to the mismatch in coefficients of thermal expansion, carbon-epoxy and glass-epoxy as well as PZT ceramic are numerically modeled by using hexahedral solid elements. Because the modeling of these thin layers increases the number of degrees of freedom, large-scale structural analyses are performed through the PEGASUS supercomputer, which is installed in our laboratory. In the first stage, the curved shape of the actuator and the internal stress in each layer are obtained by the cured curvature analysis. Subsequently, the displacement due to the piezoelectric force (which is resulted from applied voltage) is also calculated. The performance of composite curved actuator is investigated by comparing the displacements obtained by the variation of thickness and elastic modulus of laminated composite layers. In order to consider the finite deformation in the first analysis stage and include the pre-stress due to curing process in the second stage, nonlinear finite element analyses are carried out.

• 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.

• Journal of Mechanical Science and Technology
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• v.19 no.7
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• pp.1414-1423
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• 2005

This paper develops and evaluates several strategies for structural vibration control with the objective of attenuating broadband noise inside a rectangular enclosure. The strategies evaluated include model-independent collocated control, model-based feedback control and a new 'modal-estimate' feedback strategy. Collocated control requires no knowledge of model parameters and enjoys the advantage of robustness. However, effective broadband noise attenuation with colocated control requires a large number of sensor-actuator pairs. Model-based con-trollers, on the other hand, can be theoretically effective even with the use of a single actuator. However, they suffer from a lack of robustness and are unsuitable from a practical point of view for broadband structural vibration applications where the dynamic models are of large order and poorly known. A new control strategy is developed based on attenuating a few structural vibration modes that have the best coupling with the enclosure acoustics. Broadband attenuation of these important modes can be achieved using a single actuator, a limited number of accelerometers and limited knowledge of a few modal functions. Simulation results are presented to demonstrate the effectiveness of the developed strategy.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2846-2859
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• 1994

This work deals with kinematic analysis of fault-tolerant 3 degree-of-freedom spherical modules which have force redundancies in its parallel structure. The performance of a redundantly actuated four-legged module with no actuator failure, a single actuator failure, partial and half failure of dual actuator are compared to that of a three-legged module, in terms of maximum force transmission ratio, isotropic characteristics, and fault-tolerant capability. Additionally, a system with an excess number of small floating actuators is considered, and the contribution of these small actuators to the force transmission and fault-tolerant capability is evaluated. This study illustrates that the redundant actuation mode allows significant saving of input actuation effort, and also delivers a fault tolerance.

• Journal of Electrical Engineering and Technology
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• v.8 no.3
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• pp.595-602
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• 2013

An air circuit breaker (ACB) with novel double-breaker contact and permanent magnet actuator (PMA) is presented. Three-dimensional (3-D) finite element method (FEM) is employed to compute the electro-dynamic repulsion forces, including the Holm force and Lorentz force, which are acting on the static and movable contacts. The electro-dynamic repulsion forces of different contact pieces are computed, illustrating there is an optimal number of contact pieces for the ACB being studied. The electro-dynamic repulsion force of each contact, which varies from the outer position to the inner position, is also computed. Finally, the contacts of the double-breaker are manufactured according to the analyzed results to validate the simulations.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.21 no.1
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• pp.49-52
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• 2008

In this study, multilayer structured ultrasonic linear motor was simulated using Atila for investigating its optimum driving conditions. The ultrasonic linear motors mainly consist of an ultrasonic vibrator to generate elliptical displacement. The ultrasonic linear motor simulated in this paper was the use of the 1st longitudinal(Ll) and 4th bending vibrations (B4). Whit the increase of the number of piezoelectric actuator layers, displacement of node was increased. Maximum total displacement of node was about $3,91{\mu}m$ at the 13 layered ultrasonic motor under 5 V.

• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.3
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• pp.318-322
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• 2014

A kind of field bus called Actuator and Sensor interface bus(AS-i) was designed in this paper. The configuration of AS-i network system used Application Specific Integrated Circuit(ASIC) SAP5S chip and PLC S7-200 station, which included CPU 224 and AS-i master module CP 243-2. We also created an example program for PLC S7-200 to control AS-i network. The fire and smoke detection system was made with AS-i network system that was designed. This system had got more advantages than other system such as number of stations, easy installation, wide working area, etc. And designed system can be used as a partner network for higher level field bus networks.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.11
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• pp.1006-1011
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• 2004

Carbon nanotubes have outstanding properties which make them useful for a number of high-technology applications. Especially, single-walled carbon nanotube (SWNT), working under physical conditions (in aqueous solution) and converting electrical energy into mechanical energy directly, can be a good substitute for artificial muscle. The carbon nanotube structure simulated in this paper is an isotropic cantilever type with an adhesive tape which is sandwiched between two SWNTs. For predicting the geometrical and physical parameters such as deflection, slope, bending moment and induced force with various applied voltages, the analytical model for a 3 layer bimorph nanotube actuator is developed by applying Euler-Bernoulli beam theory. The governing equation and boundary conditions are derived from energy Principles. Also, the brief history of carbon nonotube is overviewed and its properties are compared with other functional materials. Moreover, an electro-mechanical coupling coefficient of the carbon nanotube actuator is discussed to identify the electro-mechanical energy efficiency.

• Transactions of the Society of Information Storage Systems
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• v.7 no.2
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• pp.75-79
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• 2011

Recently mobile phone camera become generally spread, it is required to develop high resolution, multi-functional camera module for obtaining high image quality. To satisfy this demand, number of pixels has been increased and pixel size decreased in small mobile phone cameras. As a result, image quality is seriously dropped by blur phenomena. Especially when hand tremble is occurred, image quality is dropped by camera shake. Therefore, to obtain high quality image, it is necessary to compensate user's hand tremble. In this paper, we propose voice coil actuator for compensating hand tremble, which can apply optical image stabilization (OIS) system. Sensitivity analysis and size optimization are performed to obtain high driving force. Finally, it is confirmed that the optimized electromagnetic circuit can be applied in OIS system.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.36-42
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• 2002

This paper presents two actuators for levitation using repulsions of permanent magnet and two magnetic levitation tables using the actuators. Here, one actuator for levitation consists of one fixed magnet and one moving magnet, and the other actuator consists of two fixed magnets and one moving magnet. The moving part of the magnetic levitation table contains the moving magnets. repulsive forces caused by the permanent magnets are linearized, and then the equation of motion of the moving part of the table is derived. Using the equation of motion, stability conditions of the moving part are deduced. The stability conditions are analyzed for positional relations of the moving magnets and the minimum number of active control required for stable system. As a result, in the each case of magnetic levitation tables, the requirements for stabilization are expressed by the positional relations and the number of the active controls.