• Journal of the Korean Society of Manufacturing Process Engineers
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• v.11 no.4
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• pp.104-110
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• 2012

The spindle with a built-in motor can be used to simplify the structure of machine tool system, while the rotor has unbalance mass inevitably. A high-speed spindle can be very sensitive to rotating mass unbalance which has harmful effect on many machine tools. Therefore, the balancing procedure to reduce vibration in rotating system is certainly needed for all high-speed spindles. So, it was performed with a spindle-bearing system for CNC automatic lathe by using numerical procedure. The spindle is supported by the angular contact ball bearings and the motor rotor is fixed at the middle of spindle. The spindle-bearing system has been investigated using combined methodologies of finite elements and transfer matrices. The balancing was performed through influence coefficient method and the comparison was made by whirl responses between before balancing and after balancing. As a result, balancing of simple spindle model reduced whirl orbit magnitude in case of a completely assembled spindle model.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.4
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• pp.522-530
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• 2018

This study proposes the mitigation method of shaft voltage by varying the parasitic capacitance. First, the shaft voltage explained. Second, the parasitic capacitances causing shaft voltage are analyzed respect to geometry of motor and windings. Then, the equivalent circuit is established to obtain the shaft voltage and output torque characteristic and develope appropriate motor structure. Finally, simulation and experiment are conducted to verify that modified motor suppress the shaft voltage. This novel model does not require additional hardware.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.87-94
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• 2002

In order to manufacture a precision mold/die by machining, users need high speed ＆ precision mold/die machining center. So, for development of this machine, we intend to use linear motor that is instead of ball-screw, servo-motor and coupling, high-speed spindle of pressurized air journal bearing and composite materials. In this paper we research column moving type and table moving type. The former is mainly piling 3 axes on one moving body, the latter is consist of two independent carriages. Both types are available to high speed & precision machine, but we finally draw a conclusion column moving type due to an advantage of high-speed control of linear motor.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.16-18
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• 2007

The Super High-Speed Motor is a turbo machine which operates at high speed, so air foil bearings suit their purpose as bearing elements. The rotordynamic stability was predicted using the numerical analysis of air foil bearings. From this study, the stability of rotor of the Super High-Speed Motor was confirmed by campbell diagram and logarithmic decrement.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.10a
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• pp.237-242
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• 2001

This paper presents the thermal characteristics analysis of a high-speed HMC spindle system with angular contact ball bearings, built-in motor, oil-jet lubrication method, oil jacket cooling method, and so on. The spindle system is composed of the main spindle and sub-spindle which are mechanically connected by a flexible coupling. The spindles are supported by two front and rear bearings, and the built-in motor is located between the front and rear bearings of the sub-spindle. The thermal analysis model of spindle system is constructed by the finite element method, and the thermal characteristics in the design stage are estimated based on temperature distribution, heat flow and thermal deformation under the various testing conditions related to material of bearing ball, spindle speed and coolant temperature.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.846-851
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• 1995

A motor-integrated high-speed spindle system with .psi. 65*25, 000rpm is modeled for analytical and experimental studies related to the dynamic characteristics. And the systematic and rational identification processes for evaluating the material properties of spindle and built-in motor is introduced. The impulse excitation method is applied for the experimental model testing, and the dynamic characteristics of test model is theoretically analysed by using the finite element method based on Timoshenko theory. Especially, the experimental and theoetical results reveal that the test model under the required operational conditions has no critical problem for dynamic characteristics.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.384-388
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• 2004

High frequency common mode voltage produced by power inverters are a major cause of conducted EMI, creating motor ground currents, bearing currents and other harmful by products. This paper focuses on a new SVPWM method with random PWM injection to reduce conducted EMI noise. A New PWM technique associated with the common mode voltage can be significantly reducing and contributes to mitigate. The common mode voltage to $50\%$ in comparison with that for conventional SVPWM technique. Validation of the theory and reduction methods are then performed experiment ally based on an induction motor drive.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07b
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• pp.674-677
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• 2002

In this paper, two kinds of windmill type motors which have a disk shape and a ring shape piezoelectric ceramics were studied. And characteristics of two models were compared with each others. A windmill type ultrasonic motor is composed of a stator, a rotor, and a ball bearing. The stator is made of a piezoelectric ceramics and two metals endcaps. When the piezoelectric ceramics vibrate, displacement of torsonal vibration appear at metal endcaps. The motor with 11.0[mm] diameter was studied by finite element analysis. The voltage of 100[V] was supplied at each model. Resonance frequency of 206.875[KHz] was obtained at the disk type, but ring type was 137.562[KHz]. The maximum torsonal displacement of $1.112[{\mu}m]$ was obtained at the disk type, but ring type was $1.698[{\mu}m]$.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.624-628
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• 1996

Unsteady-state temperature distributions in the high precision spindle system with built-in motor are studied. For the analysis, three dimensional model is built for the high precision spindle. The three dimensional model includes the estimation on the amount of heat generation of bearing and built-in motor and the thermal characteristic values such as heat transfer coefficient. Temperature distributions are computed using the finite element method. Analysis results are compared with the measured data. Analysis shows that temperature distributions of high precision spindle system can be estimated resonably using the three dimensional model through the finite element method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.381.1-381
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• 2002

The A lot of rotating machinery are generally used in industrial field and the electrical machinery such as the motor and generator account for the most of the part. Generally motor and generator have electrical loss because of eddy current. So silicon steel sheets are used in order to reduce the electrical loss and furthermore laminated rotor is used for motor and generator to eliminate the electrical loss and heat generation. (omitted)