• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.9-14
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• 2016

This study evaluated a digital locking device design using detection distance of 13.4mm of a human body sensing type magnetic field coil. In contrast to digital locking devices that are used nowadays, the existing serial number entering buttons, lighting, number cover, corresponding pcb, exterior case, and data delivery cables have been deleted and are only composed of control ON/OFF power switches and emergency terminals. When the magnetic field coil substrates installed inside the inner case detects the electric resistance delivered from the opposite side of the 12mm interval exterior contacting the glass body part, the corresponding induced current flows. At this time, the magnetic field coil takes the role as a sensor when coil frequency of the circular coil is transformed. The magnetic coil as a sensor detects a change in the oscillation frequency output before and after the body is detected. This is then amplified to larger than 2,000%, transformed into digital signals, and delivered to exclusive software to compare and search for embedded data. The detection time followed by the touch area of the body standard to a $12.8{\emptyset}$ magnetic field coil was 30% contrast at 0.08sec and 80% contrast at 0.03sec, in which the detection distance was 13.4mm, showing the best level.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.61-63
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• 2007

In high field (> 3 T) MR imaging, the magnetic field inhomogeneity in the target object increases due to the nonuniform electro-magnetic characteristics and relatively high Larmor frequency. Especially in the body imaging, the effect causes more serious problems resulting in locally high SAR(Specific Absorption Ratio). In this paper, we propose an optimized parallel-transmission RF coil element structure and show the utility of the coil by FDTD simulations to overcome the unwanted effects. Three types of TX coil elements are tested to maximize the efficiency and their driving patterns(amplitude and phase) optimized to have adequate field homogeneity, proper SAR level, and sufficient field strength. For the proposed coil element of 25 cm ${\times}$ 8 cm loop structure with 12 channels for a 3.0 T body coil, the 73% field non-uniformity without optimization was reduced to about 26% after optimization of driving patterns. The experimental as well as simulation results show the utility of the proposed parallel driving scheme is clinically useful for (ultra) high field MRI.

• Journal of the Korean Magnetics Society
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• v.25 no.5
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• pp.162-168
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• 2015

The ${\mu}$-turn coil having a width of ${\mu}m$ on the GMR-SV (giant magnetoresistance-spin valve) device based on the antiferromagnetic IrMn layer was fabricated by using the optical lithography process. In the case of GMR-SV film and GMR-SV device, the magnetoresistance ratios and the magnetic sensitivities are 4.4%, 2.0%/Oe and 1.6 %, 0.1%/Oe, respectively. In the y-z plane the distribution of magnetic field of GMR-SV device and $10{\mu}$-turns coil which put under the several magnetic bead(MB)s with a diameter of $1{\mu}m$ attached to RBC (red blood cell) was analyzed by the computer simulation using the finite element method. When the AC currents of 20 kHz from 0.1 mA to 10.0 mA flow to the 10 turns ${\mu}$-coil, the magnetic field at the position of $z=0{\mu}m$ at the center of coil was calculated from $30.1{\mu}T$ to $3060{\mu}T$ in proportion to the current. The magnetic field at the position of $z=10{\mu}m$ was decreased to one-sixth of that of $z=0{\mu}m$. It was confirmed that the $10{\mu}$-turn coil having enough magnitude of magnetic field for the capture of RBC is possible to use as a biosensor for the detection of magnetic beads attached to RBC.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.7
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• pp.78-82
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• 2011

In this paper, magnetic field compensation system with an open architecture and can be installed indoors is designed and measured by fabricated. To verify the shielding effectiveness, two rectangular helmholtz coils with 3-axis are fabricated to generate magnetic field and measured magnetic field inside compensation coil for 1~60[Hz], According to measurements, AC shielding effectiveness of compensation system is 96[%] of 1[Hz], 95[%] of 30[Hz] and 90[%] of 60[Hz]. The performance of system therefore can be used as the magnetically shielded room for medical and industrial field.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.12
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• pp.2343-2351
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• 2007

In this paper, we describe the design and implementation of time-varying magnetic field stimulator. Novel design for power supply part to generate high repetitive magnetic field for very short time(less than $300{\mu}s$) was achieved. Using the novel designed power supply part and the circular type coil probe, we've achieved high magnetic field up to 1.2 Tesla in 20Hz repetition rate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.601-604
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• 2003

The magnetic field generated in the iron core, which is required for the magnetic field to link each coil of the flux-lock type reactor, affects the fault current limiting characteristics of the flux-lock type high-Tc superconducting fault current limiter(SFCL). By applying numerical analysis for equivalent circuit of flux-lock type SFCL, the magnetic field induced in the iron core including currents of each coil was investigated. Through the analysis of magnetic field, we have analyzed that the magnetic field linked the 3rd coil, which is wound in the iron core, prevents the saturation of the iron core, but decreases the impedance of the flux-lock type SFCL.

• Journal of the Korean Society for Precision Engineering
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• v.10 no.3
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• pp.117-124
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• 1993

This paper presents the study on the magnetic field analysis of magnetid deflection yoke using integral equation method. An integral equation method is developed for the computer modeling of the magnetic fields produced by color CRT and T.V. deflection yoke. Deflection of electron beams using magnetic fields is applied in a variety of display instruments such as te.evision receivers, electron probe instruments, etc. The magnetic field is solved by dividing these into the finite elements in the whole domain : the saddle coil which deflects the electron heam horizontally, the toroidal coil which deflects it vertically, magnetic core which enhances the magnetid fields genterated by the both coils. Using oblate spheroidal coordinates, this paper has had an easier access to the shape of magnetic deflection yoke chasing the boundaries than other coordinates.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.905-909
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• 1995

We constructed the large 3-axis square Helmholtz coil system for the power frequency magnetic field immunity test. We measured the coil factors and magnetic field homogeneities of the fabricated 3-axis square Helmholtz coil. The experimental results for the field homogeneities are in agreement with the theoretical data. From these results, we determined the effective areas for the immunity test. We also confirmed that the low current using the multi-turns coil can be applicable to the immunity test for the high field in short duration.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.76-76
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• 2002

Purpose： The purpose of this study is to optimize the configuration of body RF coil composed of 4 planar subcoils for low field open MRI. Method： Our low field RE coil is composed of 4 subcoils assumed to be located at both the bottom and top sides of permanent magnet. Each subcoils has 3 main strips. The coil system has mirror inversion symmetry. First, the currents on the strips are obtained by inductance calculation and circuit analysis, Second, all the strips are divided into line strip elements across the strips, the self Inductances of line strip elements and the mutual inductances among the line strip elements are calculated, and current distributions of strip are obtained by circuit analysis, where each strip is considered as parallel combination of line strip elements. Finally all the line strip elements are segmented, magnetic field has been calculated by pseudo electric dipole radiation method, where the current elements are regarded as pseudo electric dipole radiation sources. We have performed above procedures for various configurations of RE coil. The field homogeneity is calculated in the 25 cm DSV.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.6
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• pp.657-665
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• 2019

In this study, we conducted a study on the transcranial magnetic electrode, a method for the study of dementia and muscle pain, a neurodegenerative disease caused by an aging society, which is becoming a problem worldwide. In particular, transcranial magnetic electrodes have been studied to improve their ability to be deteriorated by dementia symptoms such as speech, cognitive ability, and memory by outputting magnetism deep into the brain using coils on the head epidermis. In this study, simulation was performed using Maxwell 3D program for the design of coil, the core of transcranial magnetic electrode. As a result of the simulation comparison between the coil designed by the previous research and the coil through the research and development, the output was found to be superior to the conventional designed coil. The graphs of the coil outputs of B-Field and H-Field are found to be symmetrical, but the symmetry between each coil is pseudo-symmetrical and not accurate. Based on these results, an experiment was conducted to confirm whether the output of the head epidermis through both coils is possible. In the magnitude field of the reverse-coil 2-coil analysis, the maximum output was 3.3920e + 004 H [A_per_meter], and the vector field showed the strongest magnetic field around 35 to 165 degrees. It was confirmed that the magnetic output canceled due to the magnetic output. In the case of the forward 2-coil, a maximum of 3.2348e + 004H [A_per_meter] similar to the reverse coil was observed, but in the case of the vector field, the magnetic output regarding the forward output and the head skin output was confirmed. However, when the height change in the output coil, the magnetic output was reduced.