• 한국공작기계학회논문집
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• 제15권1호
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• pp.32-38
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• 2006

The magnetic fluid polishing technique can polish the tool of complex shape, because the polishing method which polishes as compress the workpiece by the magnetism abrasives to arrange to the linear according to the line of magnetic force. Therefore, we producted the magnetic fluid polishing device in order that mirror like finishing processes the tool surface. In order to a polishing condition selection, polishing characteristic was estimated by polishing conditions which are magnetic flux density, polishing speed, grain size, magnetic fluid. The tool was polished to the selected polishing condition. The result to evaluate the polished tool's performance with the cutting force and tool wear, the polished tool's performance was improved compared with the tool not to polish.

• Tribology and Lubricants
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• 제10권4호
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• pp.27-32
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• 1994

The capacitive type transducers measure the displacement of rotating shaft using the voltage difference which is formed between the sensor plates and rotor so that the measured signal is not affected by the magnetic field generated by the magnetic bearing. In this paper, the capacitive transducers are embedded inside of the magnetic bearing. In order to verify the support characteristics of the capacitance sensor-magnetic bearing system, we experimented and analyzed the magnetic bearing-rotating shaft system up to 12,000 rpm. The magnetic bearing system proposed in this paper, successfully supports the rotating shaft and we can remain the maximum displacement below $5 \mu m$ at 12,000 rpm.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권10호
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• pp.501-506
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• 2003

A Superconducting Rotary Machine (SRM) is characterized by an air-cored machine with its rotor iron and stator iron teeth removed. For this reason, the SRM is featured by 3D magnetic flux distribution, which decreases in the direction of axis. Therefore, 3D magnetic field analysis method is required to know about characteristic of magnetic field distribution of SRM. In this paper, 3D flux distribution of SRM is calculated by analytical method. The magnetic field distribution of the field coils is calculated by Biot-Savart equation. The magnetic core is represented by magnetic surface polarities. This paper describes the combined use of above methods for the total field computation, and compares results of analytical method and 3D FEM(Finite Element Method).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 B
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• pp.312-314
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• 2000

The electric wave propagation characteristics of electromagnetic field by induction current shows a nonlinear distinction in the metal but linear on air. This paper is written about the magnetic transmission distinction in the metalic tube, which wrapped the center axis by the same direction. The electromagnetic field made by the transmission signal is transferred from the transmission coil area toward the receiving coil by the magnetic diffusion. So, it is different magnetic flux around the coil with one in the remote field area. Analyzing such a complex magnetic characteristic, we verified this theory by the vector analysis and presented eddy current mechanism and analytical model about magnetic distribution in the remote field area. This magnetic distribution rate in metal body will be very useful in the nondestructive inspection of the eddy current in remote field which is recently rising as a new technology.

• 전기학회논문지
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• 제64권11호
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• pp.1551-1557
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• 2015

Magnetic coupling is used where required high reliability. because magnetic coupling's durability is stronger than mechanical coupling's durability. This paper shows the characteristics of radially magnetized tubular type magnetic coupling by using Analytical method such as space harmonic method. Analytical method was used, to find force characteristics. First, on the basis of the magnetic vector potential and two-dimensional(2-D) polar-coordinate system, the magnetic field solutions of the radially magnetized permanent magnet are obtained. And we obtain the analytical solutions for the flux density produced by permanent magnet. Finally, we can calculate the force by using the Maxwell stress tensor. And then, Finite element method(FEM) is used to validate force characteristics.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.208-211
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• 2000

We prepared Co-Cr-Ta and Co-Cr-Ta/Ti thin film for perpendicular magnetic recording media by facing targets sputtering system (FTS system). Ti underlayer effects on crystallographic and magnetic characteristics of Co-Cr-Ta perpendicular magnetic recording media have been investigated. Crystallgraphic and magnetic characteristic of prepared thin films were evaluated by x-ray diffractometry(XRD), vibrating sample magnetometer(VSM) and kerr hysteresis loop measurement. The coercivity and anisotropy field increase by introduced Ti underlayer when substrate temperature is higher than 150$^{\circ}C$. The c-axis dispersion angle and grain size of Co-Cr-Ta/Ti thin film is decrease than Co-Cr-Ta when substrate temperature is higher than 100$^{\circ}C$. Consequently, the use of a Ti underlayer highly orientated can be improved crystallographic and magnetic characteristics of Co-Cr -Ta perpendicular media layer.

• 전기학회논문지
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• 제68권1호
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• pp.36-43
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• 2019

In this paper, the characteristics of the coaxial magnetic gear according to the shape of the same gear ratio are analyzed using the two - dimensional finite element analysis. The rotor shape is SMCMG, CPCMG and RCMG. After this we analyzed the characteristics according to three shapes. Also, the amount of permanent magnet used in each shape was compared. Next, characteristics analysis of the magnetic gear according to the shape at the same torque was performed. And the total weight and efficiency of the magnetic gears were compared and verified.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권6호
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• pp.403-410
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• 2000

This paper deals with a study to improve the performance of Moving Coil type Linear Oscillatory Actuator (MC-LOA) considering unbalanced magnetic circuit. MC-LOA has an unbalanced magnetic circuit due to its asymmetric structure. In this type of LOA, the airgap flux density tends to have different magnitude along mover's displacement and the current directions. The above property causes eccentric of displacement center and interferes with the proper oscillation of LOA. Therefore, this paper presents two models having the unbalanced magnetic circuit and the other balanced by the saturated core. In order to compare the characteristics between the two models, a characteristic analysis for both the basic model and the improved model is performed by their dynamic analysis composed of kinetic and electric equations and Finite Element Method (FEM). The propriety of the improved model is verified through the experimental results.

• 한국철도학회논문집
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• 제15권3호
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• pp.237-243
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• 2012

3차원 유한요소법을 이용하여 엔드코일 효과를 고려한 SRM의 자계해석을 수행하였다. 고정자 극 형상에 따른 자계특성의 비교를 통하여 제안된 형상에서 자계특성이 향상됨을 확인하였다. 해석한 자계특성을 적용하여 철도부하에 대한 PI 제어기와 슬라이딩모드 제어기의 속도제어를 수행하였다. 속도 제어 시뮬레이션은 Matlab-Simulink를 사용하여 구현되었으며 부하 가변 조건에서 슬라이딩모드 제어기가 PI 제어기에 비해 더 우수한 과도응답 및 정상상태응답을 나타냄을 확인하였다.

• 조명전기설비학회논문지
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• 제20권2호
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• pp.81-88
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• 2006

본 연구에서는 뇌방전의 전기적 특성에 대해 파악하고자 전계 및 자계 측정시스템을 구축하였다. 주파수 대역 및 응답감도는 전계측정시스템 $40[Hz]{\sim}2.6[MHz]$, 2.1[(V/m)/mV], 자계 측정시스템 $300[Hz]{\sim}1[MHz]$, 28[nT/mV]이다. 구축한 측정시스템을 이용하여 뇌방전에 의해 발생한 전계와 자계 파형을 관측하고, 파형의 여러 가지 파라미터에 대해 통계적으로 분석하였다. 그 결과 전계와 자계 파형은 극성의존성이 미약하였으며, 전계와 자계 파형의 상승시간과 영점교차시간의 평균값은 각각 $5.5[{\mu}s],\;21[{\mu}s]$로 나타났다.