• Journal of Korean Elementary Science Education
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• v.23 no.2
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• pp.141-151
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• 2004

Pre-service teachers' understandings on magnet was investigated through the questionnaire method. The questionnaire was composed of 17 questions about the strength of magnet, the magnetized object and the direction of magnetic field around magnet. In this investigation study, 225 pre-service teachers were selected through random sampling method, who were sophomores in a National University of Education. The formation rate of the scientific conceptions on the strength of magnet was 30.3% and that on the direction of magnetic field around magnet was 53.9%. The average formation rate of scientific conception of all questions on magnet was 44.13%, which doesn't seem to be high as expected. It shows that many of subjects of the questionnaire don't understand fully the concept of moleclar magnet model and the superposition effects of magnetic field around magnet. The formation rate of the scientific conception on magnet of females who took courses in sciences in high school were higher than that of females who took courses in arts in high school, which had meaningful difference (p<.05).

• Journal of Magnetics
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• v.15 no.3
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• pp.128-131
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• 2010

In this paper, we propose a new design of the permanent magnet reluctance wheel which will make it possible to attach the robot to a vertical plane and move it. In the newly suggested design, a permanent magnet is utilized to enhance the adhesive force during attachment, and an electromagnet is produced to weaken the magnetic field of the permanent magnet and reduce the adhesive force for easier detachment of wheels from steel plates. To characterize the performance of this new wheel design, a 3-D finite element analysis is executed using a commercial FE program. The results show that the adhesive force is reduced effectively by the electromagnet which flows in the reverse direction of the magnetic loop of the permanent magnet when the current is supplied to the coil.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.794-795
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• 2008

In this paper, eddy current compensation method of 2D finite element method(FEM) is studied compared with 3D FEM. The result of eddy current loss of permeant magnet is different from 3D FEM result because current loop of the inside of permanent magnet can not expressed by 2D FEM. In order to reduce the error between 2D and 3D FEM, permanent magnet conductivity is compensated considering current loop of magnet shape according to length and width.

• Journal of Magnetics
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• v.18 no.3
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• pp.276-282
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• 2013

In this paper, magnetic flux distributions of several permanent magnet arrays, including Halbach array, are analyzed and compared. Also, braking force characteristics on a moving solid conductor in the eddy current brake systems with such magnet arrays are analyzed. Then, a new performance index taking into account the maximum braking force and the volume of the magnet is introduced for the comparison and case study of permanent magnet arrays. By changing the lengths, magnetization directions and the height of the permanent magnet arrays, a higher braking force per volume of the magnet can be achieved.

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.2
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• pp.34-38
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• 2008

Commercially available magnetic barrel machines equipped with permanent magnets have certain limitations: work can only be finished effectively in limited areas of the container because permanent magnets are arranged two-dimensionally on the magnet disk. We overcame this problem by developing a new magnetic barrel machine equipped with a three-dimensional magnet arrangement. The effectiveness of the new machine has already been reported; this study improved the machine's polishing ability by changing the polarity of magnets on a magnet block. Polishing experiments confirmed the most effective arrangement of magnets on the magnet block. An alternating arrangement of north and south poles produced far superior polishing characteristics than a uniform arrangement of the same pole facing outward. Alternating polarity probably causes increased quantities of barrel media to work together. Finally, we introduced stronger permanent magnets to the magnet block, and found that the increased magnetic field also improved polishing ability.

• Journal of the Semiconductor & Display Technology
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• v.11 no.2
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• pp.1-6
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• 2012

In this study, a high performance rotary magnet type magnetron source for roll-to-roll sputter system has been developed. We analyzed the density of magnetic field as a function of size variation of the magnet which are in the center and edge of the target. The target efficiency showed the best result when the width of center magnet, the width of edge magnet, the angle of edge magnet, and the rotation angle of Yoke are 20mm, 10mm, $56^{\circ}$, and $16^{\circ}$, respectively. On the basis of the results of magnet array, Roll-to Roll magnetron source was fabricated and tested. The uniformity of the film thickness and that of the sheet resistance was ${\pm}1.62%$ and ${\pm}4.13%$, and the resistivity was $2.79{\times}10^{-3}W{\cdot}cm$.

• Progress in Superconductivity and Cryogenics
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• v.25 no.1
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• pp.11-15
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• 2023

In recent years, the interaction force between a permanent magnet and a closed superconductor coil has been gradually investigated in depth. The principle and application potential of an energy storage/convertor composed of a magnet and a closed superconducting coil have been proved. However, the study on the force between a magnet and a non-closed superconducting coil (superconducting roll stack) has hardly been reported in previous literature. The behavior of this kind of interaction and its influence to the interaction force between a permanent and a closed superconducting coil are also still unclear. In this paper, first we investigated the interaction force between a magnet and a superconducting roll stack. Then, a series of experiments were designed and conducted to clarify the factors affected the interaction force, including the geometrical parameters of the superconducting roll stack and the magnetic field density at the roll stack. Moreover, the comparison of the interaction forces between the magnet and roll stack or a closed coil was also introduced.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1029-1031
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• 2005

A magnetic position sensor is a apparatus that detect the rotating position by measuring the value of the flux density of the rotating position. In this paper, the magnetization system of the permanent magnet in the magnetic position sensor which detects the rotating position was designed. The permanent magnet was magnetized for the flux density into the hole element to be sinusoidal distribution according to the rotating position. To make the sinusoidal distribution of flux density, the magnetization values according to the position in permanent magnet were varied by adjusting the air gap between the pole of the magnetization fixture and the surface of the permanent magnet.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.4
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• pp.398-402
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• 2014

This paper presents the comparison study of permanent magnet (PM) eddy current of concentrated winding type surface permanent magnet synchronous motor (SPMSM) with different rare-earth magnet shapes. The fractional slot winding having 10 poles and 12 slots is studied. The PM eddy current is analyzed to compare for each shape by 2 dimensional (2D) finite element analysis (FEA). The eddy current and their loss of particular position of PM as well as their distributions are displayed for each model. The effect of partly enlarged air-gap made by PM shape to PM eddy current is compared.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.82-84
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• 2009

최근 널리 사용되고 있는 BLDC Motor는 코깅 토크 문제점을 가지고 있다. 본 연구에서는 4극 24슬롯 BLDC Motor를 Flux 2D로 시뮬레이션 하였고, 문제점을 파악하여 Magnet Pole Cover를 이용한 모터를 설계하고 분석하였다.