• 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 electromagnetic engineering and science
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• v.15 no.3
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• pp.142-150
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• 2015

Several reports supported that continuous exposure to 60 Hz magnetic field (MF) induces testicular germ cell apoptosis in vivo. We recently evaluated duration- and dose-dependent effects of continuous exposure to a 60 Hz MF on the testes in mice. BALB/c male mice were exposed to a 60 Hz MF at $100{\mu}T$ for 24 hours a day for 2, 4, 6, or 8 weeks, and at 2, 20 or $200{\mu}T$ for 24 hours a day for 8 weeks. To induce the apoptosis of testicular germ cell in mice, the minimum dose is $20{\mu}T$ at continuous exposure to a 60 Hz MF for 8 weeks, and the minimum duration is 6 weeks at continuous exposure of $100{\mu}T$. Continuous exposure to a 60 Hz MF might affect duration- and dose-dependent biological processes including apoptotic cell death and spermatogenesis in the male reproductive system of mice. The safety guideline of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) indicates that the permissible maximum magnetic flux density for general public exposure is $200{\mu}T$ at 60 Hz EMF (ICNIRP Guidelines, 2010). In the present study, we aimed to examine the expression of pro- and anti-apoptotic genes regulated by the continuous exposure to 60 Hz at $200{\mu}T$ in Sprague-Dawley rats for 20 weeks. The continuous exposure to 60 Hz at $200{\mu}T$ does not affect the body and testicular weight in rats. However, exposure to 60 Hz MF significantly affects testicular germ cell apoptosis and sperm count. Further, the apoptosis-related gene was scrutinized after exposure to 60 Hz at $200{\mu}T$ for 20 weeks. We found that the message level of endonuclease G (EndoG) was greatly increased following the exposure to 60 Hz at $200{\mu}T$ compared with sham control. These data suggested that 60 Hz magnetic field induced testicular germ cell apoptosis through mitochondrial protein Endo G.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.6
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• pp.154-159
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• 2010

In this paper, the magnetically shielded room for low magnetic field shielding is designed and measured by fabricated. The size of magnetically shielded room was 3.0[m](W)$\times$3.0[m](L)$\times$3.0[m](H) to enter the industrial measuring instruments and analyzed DC and AC shielding characteristics of magnetic materials with a high permeability and AC shielding characteristics by eddy current of conductive materials. As a results, shielded room dimensions were obtained. To verify the analysis results, magnetically shielded room is fabricated and the calculated results are compared with the measured results. The Measured results show good agreement with calculated results. According to measurements, 5 times of 0.1[Hz] and 86 times of 60[Hz] is achieved at low frequency. The fabricated shielding room can be used as the magnetically shielding room for low magnetic field shielding.

• Science of Emotion and Sensibility
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• v.13 no.4
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• pp.721-732
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• 2010

As increasing of electrical device usage, social concerns about the possible effects of 60Hz electromagnetic fields (EMF) on human health have increased. The number of people with self-attributed electromagnetic hypersensitivity (EHS) who complain of subjective symptoms such as headache, insomnia etc. also increased. However, we don't know whether the EHS results from psychological factor or real perception to the electromagnetic field. In this study, we simultaneously investigated physiological changes(heart rate, respiration rate, heart rate variability, alpha and beta waves in EEG), subjective symptoms and perception accuracy to assess origins of subjective symptoms according to the EMF exposure. Experiment consists of real and sham sessions and 60Hz 12.5uT magnetic field was on(real) or off(sham) to 15 EHS and 16 nonEHS. As the results, EMF exposure did not have any effects on physiological parameters or subjective symptoms for both groups. There was also no evidence that EHS group perceived the EMFs correctly than the control group. Therefore, the origins of subjective symptoms is not the 60Hz magnetic field but psychological factors.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.27 no.2
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• pp.110-119
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• 2013

As the technologies such as middle-range resonant WPT (wireless power transfer) advance that utilizes medium and low-frequency magnetic field, the importance of safety of such magnetic field is growing. The research on the effect of electromagnetic field on the human body has been mainly done on the GHz range of mobile phones, or 50~60Hz range of electric power systems. However, there has been relatively few works on the 100kHz~10MHz range used in the resonant wireless power transfer. Since there is a difference in the limiting value of magnetic field between widely used ICNIRP EMF guideline and IEEE C95.1 standard, there can be possible confusion when establishing EMF (Electromagnetic Field) standard on the wireless power transfer device in the future. In this paper, the induced current in the human body, which is the basic restriction of the EMF guideline, is calculated using Quasi-static FDTD method when 3D high-resolution human model is exposed to the 100kHz~10MHz magnetic field. Using this result, the feasibility of the magnetic field reference level in the ICNIRP guideline is analyzed.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.2
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• pp.76-81
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• 2006

This paper analysed the characteristics of current density induced inside human body by 60 Hz extremely low frequency magnetic fields according to varying conductivities of human model. Human model was composed of several organs and other parts, whose shapes were expressed by spheroids or cylinders. Organs such as the brain, heart, lungs, liver and intestines were taken into account. Applying the boundary element method to the human model, we estimated effects on the induced current distribution due to differences of the organ conductivity and shape. We find organ conductivity influences most and a cross section area and a position of organ also gives effects.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.4
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• pp.166-171
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• 2005

Shielding methods on ELF(Extremely Low Frequency) magnetic fields may include the use of induced currents, modification of magnetic field flux patterns using high permeability and/or high conductivity materials, and others. The magnetic shielding properties of enclosures can be utilized to reduce the magnetic field of current carrying conductors. In this paper, to get a more practical understanding of shielding phenomena, we have investigated the magnetic field reduction by means of 3 dimensional numerical analysis and experiments. We found copper could reduce flux density more then permalloy in both cases of box shield and cylindrical shield. Iron under l0$\mu$T of 1 phase could reduce flux density about $20\%$ more than silicon steel, but both of them under 50$\mu$T has a similar reduction rate of $10\%$. The 3 phase horizontal model gave the highest reduction rate and the 1mm thickness iron under 10$\mu$T of 3 phase lines did lowest.

• Journal of Magnetics
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• v.22 no.2
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• pp.326-332
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• 2017

The effects of exposure to an extremely low-frequency magnetic field (25 Hz 20G) on animal cells have been studied. In some reports, stimulation was performed for fixed frequency and variations in magnitude; however, animal-cell experiments have established that both parameters play an important role. The present work undertook the modeling, simulation, and development of a uniform-magnetic-field generation system with variable frequency and stimulation intensity (0-60 Hz, 1-25G) for experimentation with cell cultures in situ. The results showed a coefficient of variation less than 1 % of the magnetic-field dispersion at the working volume, which is consistent with the corresponding simulation results demonstrating a uniform magnetic field. On the other hand, long-term tests during the characterization process indicated that increments of only $0.4^{\circ}C$ in the working volume temperature will not be an interfering factor when experiments are carried out in in situ cell cultures.

• Toxicological Research
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• v.17 no.4
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• pp.279-286
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• 2001

Recently, there is an increasing nationwide concern in Korea that exposure to electric and magnetic fields in the home environment may not be safe in humans. To identify possible effects of horizontally polarized magnetic fields (MF) exposure on embryo-fetal development, timed-mated female Sprague-Dawley rats (24/group) received continuous exposure to 60 Hz MF at field strengths of 0 Gauss (sham control), 50mG,833 mG, or 5000 mG. Dams received MF of sham exposures for 22hr/day on gestation days 6 through 20. Experimentally generated MF were monitored continuously througout the study. There was no evidence of maternal toxicity of developmental toxicity in any MF-exposed groups. Mean maternal body weight, organ weights, and gross findings in groups exposed to MF did not differ from those in sham control. No significant differences in fetal deaths, fetal body weight, and placental weight were observed between MF-exposed groups and sham control. External, visceral, and skeletal examination of fetuses demonstrated no significant differences in the incidence of fetal malformations between MF-exposed and sham control groups. In conclusion, exposure of pregnant Sprague-Dawley rats to 60 Hz at MF strengths up to 5000 mG during gestation day 6-20 did not produce any biologically significant effect in either dams of fetuses.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.4 s.37
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• pp.315-321
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• 2005

Chip-on-glass technology to attach IC chip directly on the glass substrate of flat panel display was studied by using induction heating body in AC magnetic field. With applying magnetic field of 230 Oe at 14 kHz, the temperature of an induction heating body made with Cu electrodeposited film of 5 mm${\times}$5 mm size and $600{\mu}m$ thickness reached to $250^{\circ}C$ within 60 seconds. However, the temperature of the glass substrate was maintained below $100^{\circ}C$ at a distance larger than 2 mm from the Cu induction heating body. COG bonding was successfully accomplished with reflow of Sn-3.5Ag solder bumps by applying magnetic field of 230 Oe at 14 kHz for 120 seconds to a Cu induction heating body of 5mm${\times}$5mm size and $600{\mu}m$ thickness.