• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.4
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• pp.280-285
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• 2000

The conventional ultrasonic linear motors developed so far utilize a standing wave and are of a pi-type or a hybrid transducer type structure. Traveling wave type bi-direction linear motors have not been developed yet. This paper describes design of a new bi-directional ultrasonic linear motor working by means of a traveling wave. With the finite element method we design and verify validity of the new structure. And we determine its optimal structure size of design variables material and boundary conditions for proper generation of the traveling wave.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.147-149
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• 2001

The single-phase line-start permanent magnet motor has been shown to be capable of very desirable steady state performance, but known to have undesirable starting performance. This is because magnetic braking torque. So, it is very important to predict starting performance accurately when designing the line-start motors. In this paper, starting performance was calculated by combination of d-q axis voltage equations and mechanical dynamic equations. D-q axis voltage components were derived by winding angle and turns ratio transformations.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2101-2103
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• 1999

The insulation condition of stator windings was measured by dissipation factor($tan{\delta}$) test in the six high voltage motors(rated 6.6kV) which had been in service for two years. The ${\Delta}tan{\delta}$ of motor D and E was higher than that of the rest motors. The specimens were drawn out from stator windings of the high voltage motor and their were analyzed using scanning electron microscope (SEM). SEM result shows that large voids are present in the interface both turn insulation and groundwall insulation.

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.2172-2174
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• 1998

In this paper, a speed estimation based on the quick torque control is proposed to realize speed sensorless control in a full range of induction motors. The proposed method can be formulated simply from a motor circuit equation and conducted easily by detecting primary motor currents and a voltage command at every sampling time. Since the method need not the differential values of primary currents in an arithmetic of a speed, it can be expected to improve the precision of speed estimation in a very low speed area, especially. Some numerical simulations were conducted with the assumption of using a Pulse Width Modulation voltage source inverter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.79-82
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• 2002

In this paper, a single phase driven piezoelectric motor design was presented for linear motion. Two metal/ceramic composite actuators, a piezoelectric ring which was bonded to a metal endcap from one side, were used as the active elements of this motor. The motor was composed of a piezoelectric ceramic, a metal ring which has 4 arms, and a guider. Motors with 30.0[mm] and 35.0[mm] diameter were studied by finite element analysis and experiments. As results, the maximum speed of motor was obtained at resonant frequency. When the applied voltage of the motor increased, the speed was increased. Also, bidirectional motion of the motor was achieved by combining two motors which have different resonant frequency.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.779-780
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• 2006

This paper describes the effects of rotor-bar broken in induction machines. The analysis has been made on 7.5kW, 4P, 1,768[rpm], three-phase induction motors in a healthy and broken-rotor bars fault conditions at rated loading conditions. The effects of the rotor-bar broken, magnetic force are investigated by finite element method (FEM) and experiment. The results can be useful for real-time on-line monitoring of an induction motor.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.129-131
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• 1994

Rectangular type hybrid step motor is designed to generate thirty percents higher torque than existing step motors. The torque for the motor is generated by the electromagnetic force at the air gap between the stator and rotor. The generating torque is proportioned to the rotor volume, i. e. rotor diameter. The main idea in this study is that the diameter of rotor is increased to generate more torque for the same overall motor size. This motors are manufactured by varying the shape of the teeth width of the stator and rotor. The optimum shape of the teeth is selected from the standpoint as smaller step angular accuracy.

• Proceedings of the KIEE Conference
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• 2004.10a
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• pp.110-112
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• 2004

The magnetization directions of a polar anisotropic ferrite-bonded magnet are analyzed by finite element method (FEM). The influence of the width of Sm-Co magnets for magnetic field generation is investigated. The surface flux densities of the polar anisotropic magnets are analyzed and compared according to the pole number and thickness of the magnets. And the electromotive force (EMF) values of brushless DC motors with the magnets are investigated.

• Journal of the Korean Magnetics Society
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• v.6 no.5
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• pp.287-293
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• 1996

The squirrel cage rotors of induction motors may have several faults such as broken bars, bad spots in end ring and abnormal skew caused by improper processing. These faults may cause bad effects on the performance of the induction motor. This paper proposes the detecting technique of these faults by analyzing the induced current of the detecting electric magnet, using 2-D finite element method taking account of the rotor movement.

• Journal of the Semiconductor & Display Technology
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• v.10 no.4
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• pp.1-5
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• 2011

Electronics in modern life have become more miniaturized and precise and new technology of electronic components has made these trends possible. The explosive demand of electronic components needs more high-speed and accurate performance of manufacturing processes. For high-speed actuation, solenoids, voice coil motors and piezo motors have been used. A solenoid actuator characterized by low price, available small size, and convenience is one of the main components of production equipments requiring compact and high-speed actuators. Since these actuators show millisecond order responsiveness, the improvement of 1~2msec is very important in industrial applications. In this paper, the mathematical model of the solenoid is formulated and simulated using SIMULINK$^{(R)}$. To verify the model, the responses for step input with open-loop control is obtained and compared with the simulation result. In order to improve the responsiveness, Hold voltage method is introduced and optimal value between spring constant and hold voltage is suggested.