• Journal of the Korean Recycled Construction Resources Institute
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• v.2 no.2
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• pp.93-100
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• 2006

Building materials are trending toward environmental materials nowadays and the market share of those is growing. So those researches and developments for environmental property are proceeding now. The main properties of environmental products are far infrared emission, negative ion emission, electro magnetic wave shielding, and anti fungus, these products are used with shape of mortar, and spray on the finish material. But There are not much researches for the concrete, main material in construction field, with those functional properties. So in this research we evaluated slump, compressive strength and air content as basic properties for concrete using functional materials of sericite, wood pattern sand stone, carbon black and nanometric silver solution and functional properties like far infrared emission, negative ion emission, electro magnetic wave shielding, and anti fungus. The results were as follows. The most useful material in the functional materials was carbon black. Sericite and nanometric silver solution had a little effect on functional property, so it was difficult to apply to concrete, and wood pattern sand stone had a high functional property but low compressive strength, can be applied to a factory product. Anti fungus of the concrete using nanometric silver solution was not clear but if those specimens were aged in $CO_2$ gas for a long time it might apparent.

• Journal of Sensor Science and Technology
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• v.13 no.2
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• pp.110-113
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• 2004

We have designed and fabricated the YBCO single layer directly-coupled SQUID magnetometers for the purpose of magnetocardiography in a magnetically disturbed environment. The SQUID magnetometers were designed three different types of pickup coil such as solid type, PL type I and PL type II for further stable fluxed-locked-loop operation without magnetic shielding. Magnetometer was fabricated with a single layer YBCO thin film deposited on STO(100) bicrystal substrate with misorientation angle of $30^{\circ}$. We have achieved a magnetic field noise BN of 30 fT/$Hz^{1/2}$ at 100 Hz, and less than 70 fT/$Hz^{1/2}$ at 1 Hz. The PL type II SQUIDs have exhibited the most stable fluxed-locked-loop operation in a magnetically unshielded environment.

• Korean Journal of Clinical Laboratory Science
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• v.37 no.2
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• pp.123-128
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• 2005

Magnetoencephalography (MEG) is the measurement of the magnetic fields produced by electrical activity in the brain, usually conducted externally, using extremely sensitive devices such as Superconducting Quantum Interference Device (SQUID). MEG needs complex and expensive measurement settings. Because the magnetic signals emitted by the brain are on the order of a few femtoteslas (1 fT = 10-15T), shielding from external magnetic signals, including the Earth's magnetic field, is necessary. An appropriate magnetically shielded room is very expensive, and constitutes the bulk of the expense of an MEG system. MEG is a relatively new technique that promises good spatial resolution and extremely high temporal resolution, thus complementing other brain activity measurement techniques such as electroencephalography (EEG), positron emission tomography (PET), single-photon emission computed tomography (SPECT) and functional magnetic resonance imaging (fMRI). MEG combines functional information from magnetic field recordings with structural information from MRI. The clinical uses of MEG are in detecting and localizing epileptic form spiking activity in patients with epilepsy, and in localizing eloquent cortex for surgical planning in patients with brain tumors. Magnetoencephalography may be used alone or together with electroencephalography, for the measurement of spontaneous or evoked activity, and for research or clinical purposes.

• Progress in Superconductivity
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• v.8 no.2
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• pp.158-163
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• 2007

YBCO do superconducting quantum interference device (SQUID) magnetometers based on bicrystal junctions have been fabricated for magnetocardiograph (MCG) measurements. We could fabricate YBCO SQUID magnetometers having magnetic field noise of about $20fT/Hz^{1/2}$ at white noise region. We have developed an MCG system employing the high performance SQUID magnetometers. The lightweight MCG system, requiring liquid nitrogen as a coolant, consists of 6-channel SQUID sensors, an adjustable patient bed with sliding motion, and data analyses software. The MCG system could record quite clear MCG signals in a room with moderate magnetic shielding. In normal operation with multi-position MCG measurements, we could obtain clear 48-point mappings of magnetic field map and current source map with high enough signal qualities far clinical trials.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.1
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• pp.83-93
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• 1997

This paper deals with measurements and evaluation of the time-changing electric and magnetic fields at a high-voltage laboratory. The electromagnetic disturbances originate mainly from ground faults and on/off operations of electric power equipments. The electronic circuits and control devices are very sensitive to electromagnetic interferences. It is necessory to evaluate the levels of interferences for a given electromagnetic environment. The electric field was observed by the electric field sensor having the bandwidth of the range from 40 Hz to 200 MHz, and the time-changing magnetic field was measured by the loop sensor of which the output is directly proportional to the incident signal. Also, the frequency components of the time-changing electric and magnetic fields induced by an oscillatory transient current and a chopped impulse voltage were analyzed by terms of the fast Fourier transformation, and those give the information about the levels of the electromagnetic interferences and the design of the electromagnetic shielding enclosures.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.157-159
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• 1996

For the optimal design of the induction heating cooker, precise and accurate analysis of the magnetic field inside the jar must be achieved first. Until now, design methods based on experience has been used in industry field. But this takes a lot of trial and error, high cost and also long development time. So the analysis of the magnetic field distribution is very important. In this paper the magnetic field inside the induction heating cooker is analyzed by using axisymmetrical FEM(finite element method). And the method of the coil location design for the optimal heat source distribution using sensitivity analysis is developed. In addition, the shielding effect of the non-axisymmetrical 3-D ferrite structure used in induction heating cooker is also analyzed by the integral method.

• Journal of the Korea Convergence Society
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• v.11 no.11
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• pp.89-94
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• 2020

This paper proposes a better shielding method to over sampling technique. The new method uses aluminum foil for RF shielding. As a result of the phantom test, when the over-sampling technique was applied, the aliasing artifact was reduced by about 94% compared to before the application, and the case where the aluminum shielding band was applied was also reduced by about 92% compared to before application. In addition, the scan time also increased by more than 3 times in the case of the over-sampling technique, while it was found that there was no change from before the application of the aluminum shielding band Therefore, it was confirmed that the shielding band using aluminum foil can effectively remove aliasing artifacts without increasing the scan time..

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.8
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• pp.1473-1480
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• 2008

Bisumus has a low melting point, making it easier to handle. This allows us to test what type of effect diamagnetism has on electro static and magnetic field shields. However, the actual materials for experimentation have only ever been manufactured cylindrically, and so there have been no recorded cases of measurements to this effect. To understand what kind of effect pure bisumus as diamagnetism has on electro static and magnetic shields in comparison to other materials, bisumus, along with copper, aluminum and iron 스텐도, were used to make a cylinder each. These cylinders were then used to measure and compare the electro static shield and magnetic shield at different bands of frequencies, starting from a low frequency. As shown on the graph/chart/diagram, the best results were recorded for copper and bisumus as diamagnetism in an electro static field. In terms of magnetic shielding, iron provided the best results, as expected, whereas bisumus displayed minimal effect.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.81-86
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• 2003

This paper presents a numerical analysis of transient magnetic diffusion in a melt-cast-processed BSCCO-2212 tube subjected to sinusoidal applied fields. The nonlinear f-$\lrcorner$ relation obtained by experiments in liquefied $N_2$ is used to find the magnetic diffusion coefficient. The magnetic flux density, shield current density and p-J$^2$ loss are considered. According to the result of this study, the shielding current density is varied with external applied field and coordinate in the superconductor tube. The result of analysis can be used to explain the response of a Supercon -ductor-Shield-Core-Reactor subjected to sinusoidal applied fields.

• Journal of Magnetics
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• v.12 no.1
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• pp.49-52
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• 2007

We investigated annealing effect of microforged powders on magnetic properties and electromagnetic absorption behaviors for ferromagnetic Fe-Cr metal alloy powder-polymer composites. The coercive properties greatly decreased with annealing temperature and the magnetic permeability had significantly increased after microforging and subsequent annealing treatment, due to a reduction in lattice strain of the microforged powders. The power loss in the far field regime also had greatly increased after microforging and subsequent annealing treatment in frequency range from 50 MHz to 6 GHz. As a result, the electromagnetic absorption of ferromagnetic Fe-Cr alloy metal powder-polymer composites was highly improved because of the relaxation of the internal strain during annealing process.