• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.10a
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• pp.435-436
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• 2006

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.936-941
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• 2001

This paper deals with the design of oil-tree motor-driven two-stage centrifugal compressor supported by air-lubricated multi-leaf foil bearings. The design of this compressor is performed, based upon prediction of critical speeds, load capacity, and stability. It is demonstrated in this paper that multi-leaf foil bearings can be adopted to satisfactorily support this centrifugal compressor.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.166-171
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• 2001

An electric drill is a handy tool used in a machine shop, which consists of motor, gear, bearing, shaft, and case, i.e., a gear driving system. Low level vibration and noise of the electric drill can bring the assurance of the quality and reliability of the machine. The vibration sources of the electric drill should be investigated for the reduction of the vibration and noise of the system. Through the experiments in a laboratory and the various signal processing procedure for the measured vibration and sound signals, the characteristics of the vibration and noise of the electric drill are investigated. And its propagation path is sought using partial coherence technique.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.4
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• pp.261-267
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• 2000

In this study, a heavy-load servo-control driving system, which are composed of controller, electro-hydraulic servomechanism, hydraulic motor, reduction gearbox, turret slew bearing and turret structure, are investigated to simplify the servo-control system. To estimate the effect of each component, nonlinear modeling and simulation are carried out. In the first stage, to prove the validity of the performance estimation program, simulation results are compared with experimental results. In the second stage, the effect of each component of the control system is evaluated and then a simplified control system is suggested.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.723-724
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• 2008

The rotational loss is one of the most important problems for the practical applications of PM synchronous motor/generator. This rotational loss is divided as the mechanical loss by windage and bearing and iron loss by hysteresis loop and eddy current in the part of the magnetic field. So, In this paper, a double-sided PMSM/G without the iron loss is designed by analytical method of the magnetic field and estimation of the back-EMF constant represented as the design parameter. This design model consists of the double-sided PM rotor with Halbach magnetized array and coreless 3-phase winding stator. The results show that the double-sided PMSM/G without iron loss can be applicable to the required system without the rotational loss.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.7
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• pp.929-937
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• 2003

In general, the electric motor for driving the centrifuge of Decanter type is selected based on the power(starting power) necessary to start the bowl and the screw shaft. However the operation cost of the machine is dependent on the power needed at a steadily operating condition, including the power against the bearing friction and that for the sludge removal. In this paper, the formulation for the sludge-removal power is presented. Sample calculation for a specific design shows that the sludge-removal power is increased with the friction coefficient. It also reveals that the power is mainly dependent on the length of the screw blade rather than the beach angle. Further it is shown that the power increases in square of the rotational speed of the machine.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.95-98
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• 1998

Applying the magnetically levitated transportation system, which is noncontact bearing system, to solve the problems such as transformation of original form or flaw of iron plate caused by transportation of thin iron plate which required high quality as body of motor vehicle, materials of electronic devices etc.. Magnetic saturation phenomena caused by thickness of iron plate and gap size between magnets. In case of iron plate, the vibration mode will be considered since vibration occurs during transportation. In order to solve the problems caused by vibration, choose the levitation system method using numbers of magnet, magnetic saturation for thickness and length of iron plate with parameters in location and gap of magnet. In this paper, we will suggest the whole design technique of magnetically levitated transportation system, namely method of magnetic attraction and transportation system

• Electrical & Electronic Materials
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• v.10 no.9
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• pp.889-894
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• 1997

A miniaturized wind-mill type ultrasonic motor which has diameter in 12.7 mm and thickness in 2.0mm using PMN-PZT piezoelectric ceramics was fabricated. The wind-mill type ultrasonic motors has only three plate and of two wind-mill shape slotted metal endcaps a rotor whose end is hollowed out so that its periphery fits with the shape of the stator and a bearing to guide the rotor. A Finite Element Analysis was carried out to obtain the endcaps behavior under a radial displacement change of piezoelectric disk and to optimize the structure of the number of slots. Increasing the applied voltage the revolution speed of ultrasonic motors was increased. The maximum speed of 700 rpm and the maximum torque of 0.22 nN·m of the wind-mill type ultrasonic motors were obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.999-1003
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• 1996

In this study, underdeveloping heavy-load driving servo control system, which are composed of controller, electro-hydraulic servo-valve, hydraulic motor, reduction gear box, turret slew bearing and turret structure, are investigated to simplify the control system. To estimate the effect of each component, model ins and simulation of linear and nonlinear system are carried out. In the first stage, to prove the retiability of performance estimation pro-gram, simulation results are compared with experimental results. In the second stage, the effect of each component of control system is evaluated and then a simplified control system is suggested.

• Journal of KSNVE
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• v.9 no.6
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• pp.1234-1239
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• 1999

This research investigates the characteristicsw of NRRO in a 2.5" HDD by using FEM, modal testing and runout analysis, and reduces NRRO using visco-elastic damping material. Most frequency components of NRRO are generated by the defects of ball and rotating race, and they can be determined by the kinematic analysis of ball bearing. It also proposes the novel design of a spindle motor that can reduce NRRO effectively by inserting the visco-elastic damping material to one of the transmission path of NRRO, i.e., where the strain energy is highly concentrate. By this technique, NRRO is reduced by 27%. 27%.