• Journal of the Korean Society for Precision Engineering
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• v.24 no.8 s.197
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• pp.89-96
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• 2007

In this paper, a new air bearing stage with magnetic preload and a linear motor has been developed for the small precision machine systems. The new air bearing stage is unique in the sense that permanent magnets attached bottom of the iron core of table are used not only for preloading air bearings in vertical direction but also for generating thrust force by current of the coil at base. The characteristics of air bearings using porous pads were analyzed with numerical method, and the magnetic circuit model was derived for linear motor for calculating required preload force and thrust force. A prototype of single axis miniature stage with size of $120(W){\times}120(L){\times}50(H)\;mm^3$ was designed and fabricated and examined its performances, vertical stiffness, load capacity, thrust force and positioning resolution.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.4
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• pp.385-391
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• 2008

To effectively cope with a complexity of kinematic metrology due to workspace enlargement of the planar stage, the linear induction motor is suggested as its new driving source. Especially, the linear induction motor under uniform plate type of secondary doesn't inherently have a periodical force ripple which is generally shown in the brushless DC motor. But, it presents a poor transient characteristic at zero or low speed zone owing to time delay of flux settling, resulting in slow response. To improve the servo property of linear induction motor and apply successfully it to the precision stage, this paper discusses a modified vector control methodology. The controller has a novel input form, fixed d-axis current, q-axis current and forward-fed DC current, to control thrust force and normal force of the linear induction motor independently. Influence of the newly introduced input and the feasibility of controller are validated experimentally.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.6
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• pp.184-191
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• 2002

This paper presents the thermal behavior of a synchronous linear motor with high speed and force. Such a linear motor can successfully replace ball lead screw in machine tools because it has a high velocity, acceleration and good positioning accuracy. On the other hand, low efficiency and high heating up during operation are disadvantage of linear motors. For the application of linear motors to machine tools a water-cooling system is often used. In this research, structure of the linear motor and water cooler is changed to improve the thermal behavior of the linear motor. Some important effects of an integrated cooler, an U-cooler and a thermally symmetrical cooler are presented.

• International Journal of Precision Engineering and Manufacturing
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• v.6 no.1
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• pp.31-35
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• 2005

Higher productivity requires high-speed motion of machine tool axes. The iron core linear DC motor (LDM) is widely accepted as a viable candidate for high-speed machine tool feed unit. LDM, however, has two inherent disturbance force components, namely cogging and thrust force ripple. These disturbance forces directly affect the tracking accuracy of the feeding system and must be eliminated or reduced. In order to reduce motor ripple, this research adapted the feedforward compensation method and neural network control. Experiments carried out with the linear motor test setup show that these control methods are effective in reducing motor ripple.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1409-1415
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• 2010

A linear induction motor have advantages for reducing mechanical frictions and noises because it has thrust force by induced torque instead of friction force between rail and wheels. An it has additional advantage for reducing volume of bogie frame for light rail transit. The small volume causes the cost of construction down. Recently, researches of linear induction motor for thrust force of the light rail transit have been actively studied. For the rail transit, vehicle is running as follow accelerating and constant speed, finally decelerating speed passing local stops between stations. The light rail transit have only these three patterns of operating. Thus, design of that has different design specifications from others. In this paper, the linear induction motor for the light rail transit was designed considering the goal speed, accelerating time, and accelerating distance for approaching the goal speed. The designed motor was proved that it could meet the requirement of accelerating performance by2-dimensional finite element method and mechanical dynamics equation.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.10
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• pp.498-504
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• 2006

Thrust force of linear motor is one of the important factor to specify motor performance. In this study, we optimized maximizing the thrust force of TFLM(Transverse Flux Linear Motor) using Response Surface Methodology by the table of orthogonal way. The Response Surface Methodology was well adapted to make the analytical model of the maximum thrust force and enable the objective function to be easily created and a great deal of the time In computation to be saved. Therefore, it is expected that the proposed optimization procedure using the Response Surface Methodology can be easily utilized to solve the optimization problem of electric machine.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.11B no.2
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• pp.34-39
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• 2001

This paper described the forces analysis of a hybrid linear pulse motor (HLPM) with high accuracy and repeatability. The HLPM is fed from a phase current by microstepping drive. The finite element method (FEM) is employed for calculating the force. The forces between mover(forcer) and stator(platen) have been calculated using the virtual work method. The detent force, rate of tooth width to tooth pitch and magnetic saturation were analyzed to considered the distortion characteristics of static thrust. The thrust to displacement produced a high pulsating force while the normal force is much higher than the thrust force.

• International Journal of Precision Engineering and Manufacturing
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• v.4 no.5
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• pp.34-40
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• 2003

This paper presents the inertial force problem of ultrahigh-speed injection molding machine using linear motors, and presents its solutions. To make very thin products by injection molding, very high injection speed is required, and linear motors are used for this purpose. However, direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of the inertia force which is as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic to leak. In this paper, two solutions are proposed for this inertia force problem. One is the mechanical cancellation of the inertia force, and the other is to increase the nozzle contact force. With the latter solution, the stationary platen bending worsens, so a new nozzle contact mechanism is also proposed, which can prevent the stationary platen bending.

• Journal of the Korean Society for Precision Engineering
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• v.19 no.10
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• pp.171-177
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• 2002

This paper presents the inertial force problem of ultrahigh-speed injection molding machine using linear motors, and presents its solutions. To make very thin products by injection molding, very high injection speed is required, and linear motors are used for this purpose. But direct drive by linear motors may cause brief nozzle separation from the sprue bushing because of the inertia force as large as the total output thrust of the linear motors, and this momentary separation can cause molten plastic leakage. In this paper, two solutions are proposed for this inertia force problem. One is the mechanical cancellation of the inertia force, and the other to increase the nozzle contact force. With the latter solution, the stationary platen bending worsens, so a new nozzle contact mechanism is also proposed, which can prevent the stationary platen bending.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.151-152
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• 2006

Nowadays, great attention has been shown to the question of ultrasonic linear motor for accomplishing the high positioning accuracy and high driving force in the semiconductor and optical industry. Ultrasonic linear motors have many advantages such as simple structure, quick response, ability to maintain position without energy consumption, and electromagnetic effect. And BLT has attracted attention to accomplish large vibration amplitude and large mechanical force. Authors designed and developed the new type of ultra sonic linear motor with multi support mechanism, achieved 75N of output force and 0.45m/s of velocity.