• Journal of Industrial Technology
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• v.19
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• pp.9-14
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• 1999

The voice coil actuator uses the Lorentz force between the magnetic field of the permanent magnets and the electromagnets to the motions and positioning. The small size, light weight and fast dynamic response of the these type actuators lead to admit them in the micro-positioning apparatus of the micro-machining systems. In this paper, the linear motion voice coil actuator is developed for the driving and positioning the rotating electrode of the electric discharge machine (EDM). The analyzed and measured results for the actuator are compared and discussed.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.772-773
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• 2015

This paper presents a dynamic model of 2-D magnetostriction in electrical steel sheet (ESS) under rotating flux magnetization conditions and its implementation in finite element method (FEM). For an arbitrary waveform of magnetic flux density (B), the corresponding magnetostriction waveform can be predicted by the model. In order to apply the model to FEM easily, the model is based on trilinear interpolation method. As an example, the model is applied to a three-phase transformer constructed by highly grain-oriented electrical steel sheets and the numerical results by the magnetostriction model are discussed.

• Proceedings of the KIPE Conference
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• 2003.07b
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• pp.659-662
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• 2003

This paper analyzes the electro-mechanical characteristics of the spindle motor in a computer hard disk drive due to the trapezoidal and sinusoidal driving methods. The driving circuit equation is modified by considering the switching action of PWM inverter, and is coupled with the Maxwell equation for the analysis of the magnetic field. Mechanical motion of a rotor is calculated by solving Newton-Euler equation. Electro-mechanical excitation and dynamic response are characterized by analyzing the free response of a rotating rotor and Fourier analysis of the excitation force.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.109-111
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• 2002

It requires to study on accurate control skill for the technical improvement of servo system require. It needs to study on brake that has constant-torque speed range as load. In this paper, braking torque of eddy current brake between electromagnet stator and rotating disk are analyzed. The torque-speed characteristics and proper disk construction are presented in here. From the computer simulation results, it was found that eddy current braking torque is linear or approximately constant over the desired speed range depending on the rotor material, disk construction, pole number and pole displacement of stator, these are confirmed by experimental results.

• Progress in Superconductivity
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• v.1 no.2
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• pp.99-104
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• 2000

The e.m.f. induced by a normal spot moving in a superconducting foil has been investigated by using the simulation and the experiment of a simple superconducting Power Supply. The induced e.m.f. has been derived theoretically from the magnetic field distribution within the spot. It is the sum of a DC component induced constantly by the Faraday's law during the spot's movement and a pulse component induced periodically by the flux conservation law at every electrical degrees 2$\pi$ radians. The DC component of the output voltage appears slightly nonlinear to the rotating speed, having values greater than the linear approximation values. The theoretical interpretation has been verified through experiment.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.924-933
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• 2011

The possibility of noncontact excitation of vibrations in a shaft was investigated in order to enable online structural health monitoring of a shaft during its rotating condition without stop operation. The proposed noncontact exciter was devised to exclusively generate one of two shaft vibration modes, so called longitudinal and flexural. Using the prototypes and a lot of experiments on them, it was proven that bias magnetic field, exciting voltage, center frequency, and geometry of yokes have crucial impacts on its output characteristics.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.05a
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• pp.143-146
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• 2006

In this paper, a hybrid sensor is proposed that has two capabilities: The first is to sense longitudinal of flexural elastic waves selectively which are transmitted along the targe shaft, the second to measure the rotating speed of the shaft. All measurement are made in a noncontact manner since this sensor uses magnetostriction as its measuring principles. Furthermore, the switching between these two sensing capabilities are accomplished by a very simple mechanical operation. To verify the capabilities of the Proposed sensor, an Prototype sensor are fabricated and the experiments are made. The result shows this sensor can embody two sensing capabilities in one sensor configuration.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.44-46
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• 2001

This paper describes the use of the PHOENICS CFD package for the simulation of the high-current period of the arcing process in a hybrid rotating arc/auto expansion by interrupter. The operating principle of this device depends on rapid arc rotation due to the magnetic field created by the fault current through a coil which is mounted on contacts and also relies on the principle of thermal expansion created by arc energy in extinguishing chamber and finally causes pressure rise in expansion volume. This paper is divided into three main sections. The first gives a brief overview of the interrupter. The second section gives a full description of the methods used in the calculation. The final section presents some sample results for the hybrid interrupter.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.121-124
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• 2006

It is widely know that one of the most important tasks is the research of plasma for the purpose o nuclear fusion, is to make a stable confinement of high ${\beta}$ value plasma. And, for making the stable confinement, pinch pl-asma produced by reversed field has been mainly studied yet. Magnetic field has been used to hold plasma at high temperature for a long time. Reverse field has shown unstable process. Using ratio frequency, the author could control the instability of the process and formed a stable erversed field. Inthe experiment let a reversed field configuration from by adding-Bias field in advance.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.857-860
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• 2006

It is important to diminish noise source of an electric motor used in appliances. We studied on the noise reduction of BLDC motor to drive a fan. Especially, this study was focused on detent torque caused by interaction between a permanent magnet of rotor and groove in stator. This source and rotating system brought about a resonance. This paper showed that the higher harmonic component of this torque had a main factor to lessen noise. So, we had designed new magnets with shape like a peanut and pseudo-sinusoidal flux density for low-noise BLDC motor in refrigerator.