• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.6
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• pp.562-566
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• 1991

Many research and development activities have found that Superconducting Generators (SCG) have advantages such as high efficiency, light weight, small size, large unit size and good steady-state stability over conventional ones. However the transient stability of SCG is comparable to that of conventional ones. One way to improve the transient stability of SCG is to apply quick-response excitation system to the SCG. For this purpose, an SCG with an electrothermal shield of short electric time constants should be developed. In this paper, a new electrothermal shield, called slitted electrothermal shield(SES), is proposed. The SES can easily transmit radiated heat into the ends of the shield as in the conventional electrothermal shields(CES) and can easily pass magnetic flux produced by armature and field windings. By finite element analysis and experimental test, the slitting effects of SES on magnetic shielding are compared. Good agreement is obtained between simulated and test results.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.57-62
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• 2009

This paper deals with the optimal design of a shield plate in order to minimize Extremely-Low-Frequency(ELF) magnetic fields generated from three-phase bus bars. Combining an evolutionary strategy with a 3D finite element analysis tool, the main dimensions of the shield plate are sought out. The optimization procedure consists of two separated design stages to take into account all foreseen structures of the plate. In the first stage, the basic dimensions of the plate are optimized including the distance between the plate and the bus bars. Then the usefulness of the additional structures such as a slit and fillet is investigated in the second stage. Finally the optimum design of the shield plate is suggested from the viewpoint of the shielding effectiveness and manufacturing cost.

• Proceedings of the KSR Conference
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• 2003.10c
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• pp.547-551
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• 2003

This paper presents the magnetic fields shielding properties of the light rail transit which are produced by the ripple-shaped currents in the power lines. To analyze these properties, the equivalent circuit model of the DC power supply system at the light rail transit system was induced by MATLAB-SIMULINK, and with the calculated results of the ripple-shaped currents, the magnetic fields shielding properties of the light rail transit were analyzed. The results are as follows. First The frequency of the ripple-shaped currents is 200[Hz] and its magnitude is 1.5[A]. Second the magnetic fields produced by the ripple-shaped currents of the DC power supply systems are well shielded by the aluminum made body of the light rail transit.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.3
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• pp.230-236
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• 2012

Shielding the air-gap magnetic field of the electrodynamic wheel below a conductive plate and opening the shielding plate partially, a thrust force and a normal force generate on the conductive plate at the open area. But, as only the variable controlling both forces is a rotating speed of the electrodynamic wheel, it is very difficult to control the forces independently by the speed. So, we discuss a novel method controlling the forces effectively through manipulating a size of the open area. The independent control is made possible by virtue of the feature that the relative ratio between both forces is irrelevant to an air-gap length and determined uniquely for a specific rotating speed of the wheel. Therefore, the rotating speed and the size of open area become new control variables. The feasibility of the method is verified experimentally. Specially, the controllable magnetic forces are used in a noncontact conveyance of the conductive plate.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.2
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• pp.81-86
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• 2015

This study investigated electromagnetic interference (EMI) shielding effectiveness (SE) of hybrid conductive fabrics. The coaxial transmission line method was used to measure the EMI Shielding effectiveness of the conductive fabrics. We designed and constructed a measuring system, consisting of a network analyzer and a device that serves as a sample holder and at the same time as a transmission medium of incident electromagnetic waves. The measurements of SE were carried out in a frequency range from 100 MHz to 2 GHz. The results of the EMI shielding experiments showed that the maximum electromagnetic shielding effectiveness (EMSE) values of sandwich type C/A/C (carbon fiber sheet/aluminum foil tape/carbon fiber sheet) and C/Ni/C (carbon fiber sheet/magnetic shielding foil/carbon fiber sheet) samples were 55 dB and 113 dB, respectively, at a frequency of 1.9 GHz.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.690-696
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• 2021

The purpose of this study is to develop a zirconium-based alloy with low modulus and magnetic susceptibility to prevent the stress-shielding effect and the generation of artifacts. Zr-7Cu-xSn (x = 1, 5, 10, 15 mass%) alloys are prepared by an arc melting process. Microstructure characterization is performed by microscopy and X-ray diffraction. Mechanical properties are evaluated using micro Vickers hardness and compression test. The magnetic susceptibility is evaluated using a SQUID-VSM. The average magnetic susceptibility value of the Zr-7Cu-xSn alloy is 1.176 × 10^-8 cm³g^-1. Corrosion tests of zirconium-based alloys are conducted through polarization test. The average Icorr value of the Zr-7Cu-xSn alloy is 0.1912 ㎂/cm². The elastic modulus value of 14 ~ 18 GPa of the zirconium-based alloy is very similar to the elastic modulus value of 15 ~ 30 GPa of the human bone. Consequently, the Sn added zirconium alloy, Zr-7Cu-xSn, is very interesting and attractive as a biomaterial that reduces the stress-shielding effect caused by differences of elastic modulus between human bone and metallic implants. In addition, this material has the potential to be used in metallic dental implants to effectively eliminate artifacts in MRI images due to low magnetic susceptibility.

• Proceedings of the Korean Magnestics Society Conference
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• 1998.05a
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• pp.64-65
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• 1998

• Proceedings of the Korean Magnestics Society Conference
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• 2000.09a
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• pp.576-577
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• 2000

• Proceedings of the Materials Research Society of Korea Conference
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• 1998.11a
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• pp.78-78
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• 1998

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1538-1540
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• 1999

For the development of electro magnetic shielding materials by use of the conductive polymer, measuring technique related to their shielding effect should be well established. For this propose, several commercialized techniques based on different conception have been well compared in order to adopt appropriate method to our materials under development and then, flanged coaxial holder type fixture device has been fabricated and tested satisfied performance has been obtained showing over 90dB in dynamic range with accuracy of +/-2dB.