• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.151-155
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• 2007

In this paper, we have analyzed EMI characteristics for the most widely used LED light source for general light purposes. The magnetic field induced current of LED light source and noise terminal voltage for each electric power line has been measured and analyzed. we conclude it is used as a reference when the standards related to LED light source are proposed.

• Journal of the Korean Vacuum Society
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• v.7 no.3
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• pp.273-276
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• 1998

Three different parallel antennas are designed to investigate plasma uniformity and magnetic field using a double Langmuir probe and a magnetic probe. Butterfly antenna has the highest density of ~~$2\times10^{11}(\textrmcm^{-3})$ among the three antennas and has electron temperature less than 2 eV, lower than the spiral antenna. It is found that the power efficiency becomes lower with spaced parallel antenna elements due to oppositely directed currents and positive coupling.

• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.12-14
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• 2009

초전도 DC 마그네트에 영구전류 (Persistent Current)를 흘리기 위해서는 초전도 접합(Superconducting Joint)이 필요하다. 저온 초전도 선재는 초전도 접합이 가능하며 고온 초전도체 중 BSCCO 선재로도 초전도 접합을 만들 수 있다. 그러나 최근 개발되어 향후의 초전도기기에 적용될 2세대 초전도 선재인 ReBCO CC(Coated Conductor)로는 아직 초전도 접합을 만들 수 없다. 본 연구에서는 광폭 선재의 중심을 가르고 양 종단부가 그대로 붙여진 형태의 선재를 이용하여 영구전류를 홀릴 수 있는 고온 초전도 마그네트를 제작하였다. 영구전류 초기 충전을 위하여 1.2 m 길이의 ReBCO 도체 종단부에 스테인리스 히터를 부착하여 영구전류 스위치를 구성하였다. 발생된 자기장의 시간적 균일성을 측정하기 위하여 34 시간동안 홀센서를 사용하여 대기압 액체질소 77.3 K에서 자기장을 측정하였다.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2006.05a
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• pp.418-421
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• 2006

현재 국내 외에서 GIS(Gas Insulated Switchgear)용 광 CT(optical current transformer)가 활발히 연구 개발되고 있다. 이러한 광 CT는 전력선에 발생하는 자기장에 의해 레이저 빛의 파장 각도가 변하는 현상인 Faraday Effect를 기련 원리로 한 전류측정용 기기이다. 본 논문에서는 GIS용 광 CT 개발을 목적으로 한 기초적 연구로써 자기장이 발생하는 전력선에 장착되는 센서부가 도선을 중심으로 해서 어떻게 위치하느냐에 따른 광 CT의 출력신호를 측정하여 연구하였다.

• Journal of Astronomy and Space Sciences
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• v.14 no.2
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• pp.312-319
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• 1997

The magnetometer is one of the most important payloads for scientific satellite to monitor the near-earth space environment. The electromagnetic variations of the space environment can be observed with the electric and magnetic field measurements. In practice, it is well known that the measurement of magnetic fields needs less technical complexities than that of electric fields in space. Therefore the magnetometer has long been recognized as one of the basic payloads for the scientific satellites. In this paper, we discuss the scientific fluxgate magnetometer which will be on board the KITSAT-3. The main circuit design of the present magnetometer is based on that of KITSAT-1 and -2 but its facilities have been re-designed to improve the resolution to about 5nT for scientific purpose. The calibration and noise level test of this circuit have been performed at the laboratory of the Tierra Tecnica company in Japan.

• Journal of the Korean Magnetics Society
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• v.20 no.6
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• pp.207-211
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• 2010

We have investigated the magnetoresistance effect in $Cr_5S_6$ single crystals prepared by vapor transport method. Room temperature X-ray diffraction (XRD) study reveals the phase formation of the single crystals with trigonal crystal structure. The magnetization was measured as a function of temperature (5 K~400 K) and applied magnetic field (0.1 T and 5 T). The magnetization curve as a function of temperature reveals the two transition states of $Cr_5S_6$: one from antiferromagnetic to ferrimagnetic state at ~150 K and the other from ferrimagnetic to paramagnetic state at ~300 K. Temperature dependent resistivity at 0 T and 5 T magnetic field shows the metallic behavior, showing the transition from antiferromagnetic to ferrimagnetic state at ~150 K. Magnetic field dependence of magnetization was measured at four fixed temperatures viz. 100 K, 150 K, 200 K, and 300 K. It is observed that at 200 K and 300 K it shows well M-H hysteresis behavior, whereas at 100 K and 150 K it shows non-hysteretic nature. A negative magnetoresistance (MR) of -2% is observed at 5 T for $Cr_5S_6$ single crystal at 150 K, near the antiferromagnetic transition temperature.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1065-1066
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• 2011

본 논문에서는 함정의 피탐지 성능 개선을 위한 기초 연구로 dead time 적용시 탈자 프로토콜 변화에 따른 탈자 성능 분석에 관한 연구를 하였다. 함정의 재질은 SM45C로 원통의 형태이다. 자기장 측정에 사용한 자기센서는 영국 Bartington Instruments사의 MAG-03MCB70(Three-Axis Fluxgate Magnetometer)을 사용하였으며, inter-cardinal run 방법을 이용하여 유도자기장과 영구자기장을 분리하였다. Anhyteretic deperm 프로토콜을 적용하여 탈자를 진행하였고 전류의 지속시간이 증가하는 경우에 비하여 dead time을 적용하였을 경우 탈자 성능이 향상된 결과를 얻을 수 있었다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.3
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• pp.437-444
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• 2000

In this paper, we propose a method that directly converts 3D CAD files for handheld phones designed by a commercial CAD S/W, PATRAN, to FDTD modeling with 1mm resolution. To qualify the accuracy of this method, we compared the calculation of radiation pattern using 3D transient far zone transformation with the measured results by gain comparison method in anechoic chamber and the difference is less than 0.5 dB. The calculation of magnetic field distributions on the front of handheld phones has been done to find a factor contributes to SAR. The result showed up the H-field in the width direction of the phone gives more dominant effect than the field in the length or inside to the front direction.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2000.05a
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• pp.211-214
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• 2000

This paper describes a lateral guidance system of an autonomous vehicle, using a neural network model of magneto-resistive sensor and magnetic fields. The model equation was compared with experimental sensing data. We found that the experimental result has a negligible difference from the modeling equation result. We verified that the modeling equation can be used in simulations. As the neural network controller acquires magnetic field values(B$\sub$x/, B$\sub$y/, B$\sub$z/) from the three-axis, the controller outputs a steering angle. The controller uses the back-propagation algorithms of neural network. The learning pattern acquisition was obtained using computer simulation, which is more exact than human driving. The simulation program was developed in order to verify the acquisition of the teaming pattern, learning itself, and the adequacy of the design controller. Also, the performance of the controller can be verified through simulation.

• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.1-6
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• 1997

The frequency dependence of magnetoimpedance (MI) effect in amorphous $Fe_{78}B_{13}Si_9$ alloy has been obtained. Magnetoimpedance (MI) effect is a high-frequency phenomenon, which describes the changes of impedance in any ferromagnetic sample, when a magnetic field is applied on it. MIR (Magnetoimpedance ratios) is defined as $\Delta$ Z/Z ≡ [Z (0) / Z ($H_s$)]-1 where $H_s$ is the saturating field along the long side of the sample, The MIR of the samples annealed in vacuum has been decreased normally except that the sample annealed at 5 MHz has been reached as much as 58%.