• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.362.2-362.2
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• 2016

본 실험은 CW (Continuous wave) 주파수를 가진 교류 자기장을 발생시켜 자성나노입자를 가열시키는 것이 목적이다. 이를 위해 CW 주파수 및 SMPS (Switching Mode Power Supply)를 이용해 코일에서 교류 자기장을 발생시키는 평판형 자기장 발생 장치를 자체적으로 개발하였다. 이를 이용하여 인가전압을 변화시키면서 자기장 세기의 변화를 주었다. 평판형 코일 위에는 유리 등의 원형 평판 절연체를 덮고 그 절연체 표면에 웰(Well plate)를 위치시켰고 그 안에 자성나노입자가 포함된 수용액을 넣어 교류 자기장에 노출시켰다. 자기장 측정센서(Magnetic pick up coil, Gauss Meter)를 이용하여 자기장의 세기를 측정하였고, 자성나노입자의 농도, 크기 및 자기장 세기에 따른 자성나노입자의 온도상승효과를 접촉식 온도계를 이용하여 정량적으로 측정하였다.

• Journal of the Korean Society for Nondestructive Testing
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• v.28 no.5
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• pp.395-400
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• 2008

Alternating magnetic field was used for detection of surface flaws on nonmagnetic and magnetic metallic specimens. The nondestructive sensor probe was composed of the planar coil with inductive magnetic thin film yoke as a sensing component and a single straight typed exciting coil. The planar inductive coil sensor with magnetic yoke was fabricated by sputtering, electroplating, dry etching and photolithography process. The alternative currents with the range of 0.1A to 1.0A (0.7 MHz to 1.8 MHz) were applied to the exciting coil. The specimens were prepared with the slit shaped artificial surface flaws (minimum depth and width; 0.5 mm) on metallic plate (Al; nonmagnetic metal and FeC; magnetic metal). The detected signal for the positions and shapes of surface flaws on specimens were obtained with high sensitivity and high signal to ratio. The measured output signals by the non-contacted scanning on surface of FeC specimen with micron-sized crack were converted to the images of the flaws. And these results were compared with the optical images, respectively.

• Journal of the Korean Magnetics Society
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• v.12 no.5
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• pp.174-178
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• 2002

Ac magnetic field was changed in the vicinity of a flaw because of the distribution of eddy current within a conductor, when the magnetic field was applied to a conductor having a flaw. The flaw detection was performed by using Co-based amorphous wire sensor head. The wire has almost 0 magneto-striction and high permeability. An comparative uniform magnetic field was applied to a 1㎜ thick copper plate and a 25㎛ thick aluminum sheet conductor using spiral typed coil. The size of the coil has 40㎜$\times$40㎜ outer width and 8㎜$\times$8㎜ inner width. The copper plate and the aluminum sheet has 0.5㎜ and 0.1㎜ wide gap, respectively. The frequency range of applied field was 100㎑∼600㎑. The induced voltage difference of 2.5㎷ was obtained in the maximum voltage and minimum one measured across the gap of the 1mm thick conductor. In the case of aluminum sheet, 0.4㎷ was obtained. From this results, the effectiveness of Co-based amorphous wire was confirmed in the ECT technique.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1266-1272
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• 2003

This paper presents a new class of magnetic microsensors based on the Hall effect in AC microplasma. In the theoretical study, we develop a simple model of the plasma Hall sensor and express the plasma Hall voltage as a function of magnetic field, plasma discharge field, pressure, and electrode geometry. On this basis, we have designed and fabricated magnetic microsensors using AC neon plasma. In the experiment, we have measured the Hall voltage output of the plasma microsensors for varying five different conditions, including the frequency and the magnitude of magnetic field, the frequency and the magnitude of plasma discharge voltage, and the neon pressure. The fabricated magnetic microsensors show a magnetic field sensitivity of 8.87${\pm}$0.18㎷/G with 4.48% nonlinearity.

• Proceedings of the Korean Magnestics Society Conference
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• 2009.05a
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• pp.210-211
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• 2009

• Proceedings of the Korean Magnestics Society Conference
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• 2009.05a
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• pp.207-207
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• 2009

• Proceedings of the Korean Magnestics Society Conference
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• 2012.11a
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• pp.153-154
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• 2012

• Journal of the Korean Magnetics Society
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• v.20 no.5
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• pp.178-181
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• 2010

Search coil magnetometer has been used for detection of ac magnetic field with high sensitivity. To reduce demagnetizing factor of core and increase S/N ratio of search coil magnetometer, the core was divided by two parts and coil was wound on each cores. Two coils were connected serially and put into amplifier as differential mode. Constructed 120 mm length search coil magnetometer shows linearity of 0.03%, sensitivity of 9.3 mV/nT, and resolution of 20 pT at 1 Hz.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.36-39
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• 1996

We have constructed a disp1acerrent sensor for measuring dynamic magnetostriction of an arrvrphous ribbon under alternating magnetic field using fiber optic Fabry-Perot interferorreter. The signal of the sensor was depen¬dent on the index matching oil and the optical isolator. The resolution of the sensor was $30{\AA}$ and the measured peak to peak magnetostriction of the amorphous ribbon $Fe_{81}B_{13.5}Si_{3.5}C_{2}$ was $28{\times}10^{-6}$.

• Journal of the Korean Magnetics Society
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• v.11 no.3
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• pp.134-140
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• 2001

Flux-gate magnetometer was developed in 1930's, and it has been widely used for the low magnetic field measurements. In this work, we have employed amorphous ribbon 2714A produced by Allied Chem. Co. as sensor core material. To develop low noise, low power consumption, and high reliability flux-gate magnetometer, we have measured ac magnetic properties depending on the annealing conditions. As quenched state amorphous core shows high noise level and ac magnetic properties were changed under the condition of accelerated aging test, but amorphous ribbon, which was annealed under 350 $\^{C}$ during 1 hour, shows low noise level of 0.1 nT in the frequency range of dc∼10 Hz which was 10 times better than the as quenched amorphous ribbon. Under accelerated aging test, ac magnetic properties such as squareness and coercivity of the annealed samples show higher reliability and approached to a certain limiting value as exponential function. We can see that high reliability and low noise flux-gate magnetometer could be developed, if we consider this ac magnetic properties change in the sensor design.