• 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 Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.393-398
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• 2002

In this study, the increasing gear boxes for the high speed vertical in-line centrifugal pump are developed through rotor dynamic analysis. The developed increasing gear boxes are two kinds for 18000rpm and 25000rpm at the output shaft. The gear sets suitable for high speed and high load are manufactured by investigating AGMA bending strength and AGMA surface strength severely. The rotor dynamic analysis on gear sets and bearings is performed in order to avoid the critical speeds and other troubles. As a result of study, the two increasing gear boxes for the high speed vertical in-line centrifugal pump are designed and manufactured.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11a
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• pp.343.1-343
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• 2002

In this study, the increasing gear boxes for the high speed vertical in-line centrifugal pump are developed through rotor dynamic analysis. The developed increasing gear boxes are two kinds fur 18000rpm and 25000rpm at the output shaft. The gear sets suitable for high speed and high load are manufactured by investigating AGMA bending strength and AGMA surface strength severely. The rotor dynamic analysis on gear sets and bearings is performed in order to avoid the critical speeds and other troubles. As a result of study, the two increasing gear boxes for the high speed vertical in-line centrifugal pump are designed and maunfactured.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.429-435
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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 Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.792-796
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• 2009

Application of air foil bearing (AFB) is widely using to cope with requirements of high speed and high efficiency system at turbo machinery. At same time, a wide variety of AFB design methods are required. In this paper, the AFB design factor influencing the most greatly in bearing performance was selected through theoretical analysis and vibration test was conducted using selected factor. Through this process, AFB system applicable for vehicle turbo machinery was developed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.935-940
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• 2005

In this paper, dual rotor disk configuration with a coreless stator is proposed for the Lorentz force type integrated motor bearing system. An experimental compensation for the effects of high order harmonics is performed using the digital controller of the experimental setup. The runout profile and rotor unbalance are also identified by the extended influence coefficient method. The experimental results confirm that this compensation method effectively attenuates the rotor vibration all over the operating range of rotational speed.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.733-735
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• 2001

The high temperature superconducting bulk can be used as the bearing of a motor. This paper presents the fabrication and test results of a motor with superconducting bearing using HTS bulks. The bearing used four hexahedron type YBCO bulks. Height, width and depth of the HTS bulk were 10mm, 30mm and 30mm, respectively. Single phase induction motor was used to drive the shaft and solid rotor was adopted for high speed rotation. Test results show the motor with HTS magnetic bearing can rotate silently and smoothly without any contact.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11b
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• pp.1026-1031
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• 2001

In this paper. the dynamic characteristics of a super high-speed tilting-pad air bearing(TPGB) used in a turbo expander with high expansion ratio are analyzed. The dynamic behavior and stability of a rotary system supported by two journal air bearings are investigated numerically. The transient response of the shaft is obtained by simultaneously solving the equation of motion of the shaft and the dynamic Reynolds equation. The stiffness and damping coefficients of the bearing are calculated from the loading coefficients of the bearing are calculated from the loading capacity. shaft velocity and displacement by using a curve fitting method. The natural frequencies of the 1st and 2nd rigid modes can be calculated from these coefficients. The theoretical method of a rigid rotor system is verified by experimentsut.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.191-198
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• 2002

Oil-free turbo-compressor supported by compliant foil bearings which remove oil-contamination by elimination of the conventional ball bearing and oil lubrication systems is presented. Turbo-compressor makes two individual air compression with two impellers at operating speed, 39,000rpm. In this study, the rotordynamic effects caused by aerodynamic instability were investigated with variable mass flow rate. Correlation between frequencies of pressure fluctuation in two diffusers and those of excitation forces on rotor were clearly developed in aerodynamic unsteady region. Thus, these results show that it is beneficial to design high speed rotating turbomachinery considering coupling effect between aerodynamic instability and rotordynamic force.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.310-314
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• 1999

A prototype of Flywheel Energy Storage System with high Tc superconducting bearings was fabricated and tested to verify its applicability for the energy industry. The moment of inertia of assembled wheel with rotor magnets is about 1.072${\times}$10$^{-1}$ Kg-m$^2$. The wheel was designed to withstand its integrity up to the rotation speed of 20,000 rpm. YBCO bulk superconductors prepared by seed growth method were used as bearing to levitate and stabilize the rotating wheel. High speed rotation of the flywheel without mechanical contact was achieved by using specially designed Halbach type motor. The flywheel system showed very high stability during test operation performed up to the speed of about 10,000rpm. The energy loss measured by free decay test performed between 9,300 rpm and 7,000 rpm was calculated as about 45 W.