• Journal of the Korean Society for Precision Engineering
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• v.19 no.7
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• pp.88-96
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• 2002

High-speed machining is one of the most effective technologies to improve productivity. Because of the high speed and high feed rate, high-speed machining can give great advantages for the machining of dies and molds. This paper describes on the improvement of machining accuracy in high-speed machining. Depth of cut, feed rate and spindle revolution are control factors. The effect of the control factors on machining accuracy is investigated using two-way factorial design.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.151-153
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• 2010

This paper is presented for the development of the brushless DC(BLDC) motor for the spindle motor of hard disk drives(HDD). A new BLDC Motor has the use of insulated, compacted, and iron powder for the armature core material of BLDC motors. Insulated iron powder in this paper is generally called soft magnet composite(SMC). The SMC is used for the stator of the motor instead of the laminated steel core. The motor used by SMC can have the good advantages in condition of the high frequency input power and small sized motor. It gets much more high efficiency than laminated steel core at same input power. The proposed motor has a technique of speed sensorless control. Experimental results show the performance of the proposed BLDC motors for an HDD.

• Journal of the Korean Society for Heat Treatment
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• v.29 no.2
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• pp.66-74
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• 2016

In this study, characteristics of TiAl alloy and SCM440 (Cr-Mo steel) have been investigated with the various joining condition by servo motor type friction welder. The experimental factors of friction welder used in this study are spindle revolution, friction speed, and distance, upset speed and distance, respectively. Servo motor type friction welder could be controlled by the level of oil pressure, and it could be performed by position control dependence of electrical energy. Mechanical properties and morphology of welded interface were characterized by various joining condition. This aroused due to the bond strength dependence on friction heat and size of the heat affected zone. Therefore, it is necessary to have enough friction heat and decreased heat affected zone for good friction welding between dissimilar metals. An optimum bond was obtained between TiAl alloy and SCM440 by controlling friction speed and distance. At the spindle revolution 4,000 rpm, friction speed 120 mm/min, friction distance 15 mm, the bond strength was found to be 312 MPa.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.352-357
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• 1996

Recently, Permanent Magnet Synchronous Motor(PMSM) drives are widely used for industrial applications due to its high efficiency and high power factor control strategy. PMSM generally have two classifications such as the SPMSM(Surface Permanent Magnet Synchronous Motors) and IPMSM(Inter Permanent Magnet Synchronous Motors). IPMSA has economical merits over SPMSM in higher speed range, mechanical robustness, and higher power rate by the geometric difference. The maximum torque operation in IPMSM is realized by the current angle control which is to utilize additional reluctance torque due to a rotor saliency. In traction, spindle and compressor drives, constant power operation with higher speed range are desirable. This is simply achieved in the DC motor drives by the reduction of the field current as the speed is increased. However, in the PMSM, direct control of the magnet flux is not available. The airgap flux can be weakened by the appropriate current angle control to demagnetize. In this paper, the control method of optimal current vector in IPMSM is described in order to obtain the maximum torque or maximum output with the speed and load variations. The applied algorithm is realized by the proto system with torque and speed control Experimental results show this approach is satisfied for the high performance servo applications. (author). 6 refs., 9 figs., 1 tab.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.8
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• pp.30-38
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• 2003

High-speed machining is one of the most effective technology to enhance productivity especially for hardened die material. High-speed machining can give great advantages for machining of dies and molds. But selection of machining condition is very difficult because of complicated machining mechanism. This paper presents the selection of machining condition in high-speed machining of STD11. Depth of cut, feed rate and spindle revolution are control factors. The effect of the control factors on surface roughness and machining error in Z-direction is discussed to improve machining accuracy.

• 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 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.

• Journal of Drive and Control
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• v.14 no.2
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• pp.23-29
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• 2017

In this study, a flexible multi-body dynamic simulation model of a knuckle boom crane is developed to evaluate the stress of spindle and rack gears under dynamic working conditions. It is difficult to predict potential critical damage to a knuckle boom crane if only the static condition is considered during the development process. To solve this issue, a severe working scenario (high speed with heavy load) was simulated as a boundary condition for testing the integrity of the dynamic simulation model. The crane gear model is defined as a flexible body so contact analysis was performed. The functional motion of a knuckle boom crane is generated by applying forces at each end of the rack gear, which was converted from hydraulic pressure measured for the experiment. The bending and contact stress of gears are theoretically calculated to validate the simulation model. In the simulation, the maximum stress of spindle and rack gears are observed when the crane abruptly stops. Peak impact force is produced at the contact interface between pinion and rack gears due to the inertia force of the boom. However, the maximum stress (bending/contact) of spindle and rack are under the yield stress, which is safe from damage. By using the developed simulation model, the experiment process is expected to be minimized.

• Proceedings of the KIEE Conference
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• 2005.10a
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• pp.150-154
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• 2005

This paper is presented for the development of the brushless DC(BLDC) spindle motors for hard disk drives. A new BLDC Motor has the use of insulated, compacted, iron powder for the armature core material of BLDC motors. Insulated iron powder in this paper is generally called soft magnet composite(SMC). The SMC is used for the stator of the motor instead of the laminated steel core. The motor used by SMC can have the good advantages in condition of the high frequency input power and small sized motor. It gets much more high efficiency than laminated steel core at same input power. The proposed motor has a technique of speed sensorless control. Experimental results show the performance of the proposed BLDC spindle motors for an HDD.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.10a
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• pp.43-49
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• 1997

A rotating rigid disk, attached on a flexible shaft or supported by a torsional spring, experiences precessional whirling due to gyroscopic moment loading. It is well known in rotor dynamics area that, as the rotational speed increases, the precessional mode of the rotating rigid disk starts splitting into two: forward and backward precessional modes. On the other hand, it is also well known in disk vibration area that a rotating flexible disk also shows another kind of mode splitting phenomenon due to the rotation, resulting in forward and backward traveling waves. When rotating multiple flexible disks are coupled in vibration with the supporting Flexible shaft, the associated mode splitting should be compatible with the two seemingly different vibration analysis methods. This paper investigates the possibility of fusing the precessional and traveling wave mode splittings so that the bending coupled disk vibrations in HDD spindle systems can be better understood.