• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.53-62
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• 1999

Micro polysilicon actuators, which are widely used in the field of MEMS (Microelectromechanical System) technology, were fabricated using polysilicon thin layers. Polysilicon deposition were carried out to have symmetrical layer structures with a LPCVD (Low Pressure Chemical Vapor Deposition) system, and we have measured physical characteristics by micro test patterns, such as bridges and cantilevers to verify minimal mechanical stress and stress gradient in the polysilicon layers according to the methods of mutilayer deposition, doping, and thermal treatment, also, analyzed the properties of each specimen, which have a different process condition, by XRD, and SIMS etc.. Finally, the fabricated planar polysilicon resonator, symmetrically stacked to $6.5{\mu}m$ thickness, showed Q of 1270 and oscillation ampitude of $5{\mu}m$ under DC 15V, AC 0.05V, and 1000 mtorr pressure. The developed micro polysilicon resonator can be utilized to micro gyroscope and accelerometer sensor.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.317-321
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• 2002

Piezoelectric properties of $(Pb_{1-x}Y_x)[(Ni_{1/3}Nb_{2/3})_{0.15}(Zr_{1/2}Ti_{1/2)})_{0.85}]O_{3}$ (x=0~0.05) ceramics were investigated, The stoichiometric PNN-PZT ceramics required the sintering temperature above $1100^{\circ}C$, but the addition of $Y_{2}O_{3}$ in the PNN-PZT ceramic lowered the sintering temperature down to $1000^{\circ}C$. In case of x=0.005, the electro-mechanical coupling $factor(K_p)$, the piezoelectric $constant(d_{33})$, and the maximum strain ratio of PNN-PZT ceramics sintered at $1000^{\circ}C$ were 53.1%, 395pC/N, and $2200{\times}10^{-6}$ respectively, A 30-layer piezoelectric actuator$(10{\times}10{\times}1.7mm)$ fabricated with the above material showed the maximum strain of $2.09{\mu}m$ under 100V DC bias.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1211-1214
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• 1992

AC servo motor drives, Fara DS series, proposed in this paper can be effectively used in robots, CNC machine tools, and FA system with AC servo motors as actuators. The inverter of the AC servo drive consists of IGBT (Insulated Gate Bipolar Transistor) which have high switching frequency. Noises and vibrations generated in variable speed control of AC servo motors can be greatly reduced due to their high switching frequencies. In the developed servo drive, maximum torque is always generated in the whole speed range by compensating phase shift, which results from the nonlinearies of the AC servo motor during abrupt acceleration and deceleration. Abundant protection functions are provided to prevent abnormal state of the servo motor, and furthermore diverse user options are considered provided for the effective application. The proposed AC servo motor drive is designed to minimize velocity variation with respect to external load, supply voltage, environmental temperature, and humidity, so can be widely used in the fields of factory automation including robots and CNC msachine tools.