• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.147-154
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• 2005

A precision hi-directional actuator for a high precision leveling system with $Z{\Theta}_x{\Theta}_y$ motions is proposed and designed in this paper. The actuator is composed of a force generation structure, a guide mechanism, and a symmetric structure. At first, its driving force is generated by a change of flux in air gaps by permanent and changeable flux. The permanent flux is generated by a permanent magnet. The changeable flux is created by variable current flowing through coil. The combination of permanent and changeable flux makes various flux densities in air gaps between moving part and fixed yokes. And then, the difference between flux densities in lower and upper gaps creates forces fur the $bi-direction({\pm}z)$ motion. The guide mechanism of this actuator is composed of two circular plates and one shaft. Reducing motions generated by forces except z-motion, these circular plates endow the actuator with high stiffness for fast settling time. And the function of the shaft is to transfer motion to an object. At last, total body has a symmetric structure to be stable on thermal error. The actuator is designed by MAXWELL 2D and ProMECHANICA. The designed actuator is evaluated by 8nm laser doppler vibrometer, dynamic signal analyzer, and simple PID controller.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3259-3263
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• 2007

This paper describes the proceedings of creating countermeasures after analysis and maintenance be able to conduct operation safely in a power plant. in order to operate the power plant in a stable and reliable way, the best condition of the govemor system can be maintained through the response characteristic analysis of the control device for the pitch blade control hydraulic actuator. The fan pitch blade control hydraulic actuator of a 500MW large-scale boiler is frequently operated under normal operation conditions. Common problems or malfunctions of the pitch blade control hydraulic actuators leads to the decline of boiler thermal efficiency and unexpected power plant trip. The inlet and outlet gas can be controlled by using the fan pitch blade control hydraulic actuator in order to regulate the internal pressure of the furnace and control the frequency in the power plant facility which utilizes soft coals as a power source.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.932-937
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• 2002

The polyimide nozzle and silicon restrictor inside a thermal micro actuator have been fabricated using state of the art laser micromachining methods. Numerical models of fluid dynamics inside the actuator chamber and nozzle are presented. The models include fluid flow from reservoir, bubble formation and growth, ejection through the nozzle, and dynamics of refill through restrictor. Since high tapered nozzle and restrictor are very important parameters for overall actuator performance design, a special setup for the beam delivery system has been developed. The effects of variations of nozzle thickness, diameter, taper angles, and restrictor shapes are simulated and some results are compared with the experimental results. It is fecund that the fluid ejection through the thinner and high tapered nozzle is more steady, fast, and robust and the tapered restrictor shows more satisfying refill than the zero taper one.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.282-284
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• 2011

Based on graphene oxide and multi-walled carbon nanotube layers, a wireless bi-layer actuator that can be remotely controlled with an electromagnetic induction system has been developed. The graphene-based bi-layer actuator exhibits a large one-way bending deformation under eddy current stimuli due to asymmetrical responses originating from the temperature difference of the two different carbon layers. In order to validate one-way bending actuation, the coefficients of thermal expansion of carbon nanotube and graphene oxide are mathematically formulated in this study based on the atomic bonding energy related to the bonding length. The newly designed graphene-based bi-layer actuator is highly sensitive to electromagnetic wave irradiation thus it can trigger a new actuation mode for the realization of remotely controllable actuators and is expected to have potential applications in various wireless systems.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.924-927
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• 2007

In this study, adaptation of two-way shape memory effect of SMA wire to the actuator is examined. Therefore the SMA characteristics which are training, material properties, response time at different thermal cycling rates are tested. During training, permanent deformation is accumulated till a certain number of cycle and then saturated. The amount of two-way strain is unchangeable over all cycle and the slope of strain(or stress)-temperature curve is slower as the increase of applied stress. The rate effect is observed resulted from the thermal distribution which heating profile differs from cooling as thermal cycling time. Using the estimated SMA properties, an experimental test for the simple smart wing is performed.

• Journal of Mechanical Science and Technology
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• v.20 no.3
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• pp.297-309
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• 2006

This paper deals with a novel structure for single-cell characterization which makes use of bimorph micro thermal actuators combined with electrical sensor device and integrated microfluidic channel. The goal for this device is to capture and characterize individual biocell. Quantitative and qualitative characteristics of bimorph thermal actuator were analyzed with finite element analysis methods. Furthermore, optimization for the dimension of cantilevers and integrated parallel probe systems with microfluidic channels is able to be realized through the virtual simulation for actuation and the practical fabrication of prototype of probes. The experimental value of probe deflection was in accordance with the simulated one.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.12
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• pp.36-41
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• 2007

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2003.10a
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• pp.381-385
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• 2003

This paper presents the fabrication possibility of the micro actuator which uses a micro-thermal bubble, generated by a micro-heater under pulse heating. The micro-actuator is consist of three plate. The lower plate includes the channel and chamber are fabricated on high processability silicon wafer by the DRIE(Deep Reactive ion Etching) process. The middle plate includes the chamber and diaphragm, and the upper plate is the micro-heater. The micro-heater designed non-uniform width and results in periodic generation of stable single bubbles in D.I water. The single bubble appears precisely on the narrow part of the micro-heater and control is recorded.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2003.10a
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• pp.167-170
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• 2003

In this paper, the electromechanical displacements of curved actuators using laminated composites are calculated by finite element method to design the optimal configuration of curved actuators. To predict the pre-stress in the device due to the mismatch in coefficients of thermal expansion, the carbon-epoxy and glass- epoxy as well as PZT ceramic is also numerically modeled by using hexahedral solid elements. Because the modeling of these thin layers causes the numbers of degree of freedom to increase, large-scale structural analyses are performed in a cluster system in this study. The curved shape and pre-stress in the actuator are obtained by the cured curvature analysis. The displacement under the piezoelectric force by an applied voltage is also calculated to compare the performance of curved actuator. The thickness of composite is chosen as design factor.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.813-819
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• 2006

The state of the art for the design of swing ann actuators for optical disc drives is to obtain the high efficient dynamic characteristics, especially for the small size for the mobile information devices, It is affected by the need of consumers who wants the portable digital storage devices maintaining highly functional and removable characteristics of the optical disk drive (ODD). As a necessary consequence, the need of the small form factor (SFF) storage device has been considered as an important part in the information storage technology. In this paper. we suggest a new conceptual miniaturized swing arm type actuator that has high efficient dynamic characteristics as well as satisfies the sensitivity and the heat emission requirements for the SFF-ODD. It also uses a tracking electromagnetic (EM) circuit for a focusing motion. Due to the size constraint, the thermal problem of optical head arises; therefore, we design an efficiently heat emitted structure for the actuator.