원통형 차폐 모델에 의한 극저주파 자기장 차폐 효과 해석

이명복,주성후,송기현 대한전기학회 2024 전기학회논문지 Vol.73 No.2

To shield magnetic fields in the extremely low frequency(60Hz) band generated from transmission lines and power equipment, the magnetic field shielding effect was analyzed using Faraday 3D. The analysis model was in the form of a cylindrical shielding material surrounding a wire carrying a single-phase current. The shielding material had a single-layer structure of a high-permeability magnetic layer or a highly conductive metal layer, or a multilayer structure consisting of a magnetic layer/conductive metal layer. The analysis was performed by changing physical properties such as relative magnetic permeability, electrical conductivity and the layer thickness. In the case of single-layer shielding, it was difficult to obtain high enough shielding rate with thickness less than 1mm. In the case of double-layer shielding, however, high shielding rate of 85.3% was achieved when the magnetic permeability of the primary layer was 100 and the conductivity of the secondary layer was 1.0×105 (S/m) at 0.2mm thickness of each layer. In multilayer structures consisting of three or more layers, the shielding effect was saturated.

Development of a Magnetic-field Stimulation System for Cell Cultures in situ

G. Dominguez,S. Arias,Jose L. Reyes,Pablo Rogeli 한국자기학회 2017 Journal of Magnetics Vol.22 No.2

The effects of exposure to an extremely low-frequency magnetic field (25 ㎐ 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 ㎐, 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℃ in the working volume temperature will not be an interfering factor when experiments are carried out in in situ cell cultures.

직업성 극저주파 자기장 노출평가와 노출 기준에 대한 쟁점 고찰

박동욱,이승희,조경이 한국산업보건학회 2022 한국산업보건학회지 Vol.32 No.4

Objectives: Objective of this study is to review briefly exposure characteristics, monitoring instruments and threshold limit values for extremely low frequency-magnetic field (ELF-MF) methods. This study was undertaken through brief literature review. We performed a literature search in PubMed to identify ELF-MF studies conducted in workplaces. Initial search keywords such as ‘extremely low frequency-magnetic field (ELF-MF)’ and ‘electromagnetic fields (EMF)’ combined or singly. We limited our review to occupational rather than general nonworkplace environmental exposures. Methods: The contents we reviewed: key industry and occupations generating ELF-MF, several directreading instruments monitoring ELF-MF and threshold limit values (TLV) preventing health effects may be caused by the exposure to ELF-MF. Results: The industries related to the generation and supply of electricity, electrolytic installations, welding, and induction heating and more were regarded as high ELF-MF exposure industries. All jobs handling or employed performed in power cable lines, electrical wiring, and electrical equipment are found to be exposed to ELF-MF. Threshold or ceiling limit, 1,000 μT, is established to prevent acute effects of exposure to low-frequency EMFs on the nervous system: the direct stimulation of nerve and muscle tissues and the induction of retinal phosphenes. The International Agency for Research on Cancer (IARC) has classified ELF-MF as possibly carcinogenic to humans chiefly based on epidemiological studies on childhood leukemia. However, a causal relationship between magnetic fields and several types of cancer including childhood leukemia has not been established nor has any other long-term effects. Risk management using precautionary measures, has been initiated by the US and EU to prevent chronic health efects related to ELF-MF exposure in workplaces. Conclusion: This study recommends the implementation of various measures such as theestablishment of occupational exposure limit values for ELF-MF and precautionary principle to prevent potential chronic occupational health effects may be caused by ELF-MF in Korea.

탄소계 소재를 이용한 극저주파 영역에서의 자기 차폐효과 연구

오성문,강동수,이상민,백운경,노재승,Oh, Seong Moon,Kang, Dong Su,Lee, Sang Min,Baek, Un Gyeong,Roh, Jae Seung 한국전력공사 2015 KEPCO Journal on electric power and energy Vol.1 No.1

To examine the magnetic shielding effect for carbon-based materials at extremely low frequencies (60 Hz), two types of carbon black (Super-P and Denka Black) and a natural graphite (HC-198) were mixed into organic binder at 10 wt.% to produce a coating solution, and a powder coating with varying thickness was applied on an aluminum disk measuring 88 mm in radius. A device was developed to measure the sheielding effect at extremely low frequencies. A closed circuit was achieved by connecting a transformer and a resistor. The applied voltage was fixed at 65 V, and the magnetic field was measured to being the range of 4.95~5.10 mG. Depending on the thickness of the coating layer, the magnetic field showed a decreasing trend. The maximum decrease in the magnetic field of 38.3% was measured when natural graphite was coated with specimens averaging $455{\mu}m$. This study confirmed that carbon-based materials enable magnetic shielding at extremely low frequencies, and that the magnetic shielding effect can be enhanced by varying the coating thickness.

극저주파 디지털 자계 측정기의 설계 및 구현

임재유,김원호,황정환 한국위성정보통신학회 2015 한국위성정보통신학회논문지 Vol.10 No.3

본 논문은 극저주파 자계 세기를 무선 모니터링하기 위한 디지털 자계측정기의 설계 및 구현에 대해 기술한다. 우리 실생활에 극 저주파대역의 자기장이 노출되어 있어 인체에 자기장이 얼마나 영향을 미치는가에 대한 연구의 필요성이 있으며 그에 따른 측정 장비의 수요가 증가하고 있다. 본 논문에서는 3-축 코일형 자계센서를 사용하였으며, 자계의 측정 범위는 0.03~10uT, 주파수 범위는 40~180Hz이다. 자계 세기의 측정과 주파수 특성을 보상하는 등화기능은 DSP 기반의 디지털 방식으로 설계하였으며, 측정 값은 와이파이 통신을 이용하여 PC 모니터링 할 수 있도록 설계 및 구현하였고 측정오차는 6% 이내로 실용성을 확인하였다. In this paper, we present that design and implementation of digital extreme-low-frequency (ELF) magnetic meter including wireless monitoring feature. In our lifetime, it is necessary to study how much magnetic field effects to human body. In this paper, we use 3-axis coil-type magnetic sensor, magnetic measurement range is 0.03~10uT and frequency range is 40~180Hz. As magnetic sensor characteristic, frequency loss is occurred that compensated using digital equalize based on DSP processor. Measurement value can be monitored on PC through Wifi communication and measurement error is observed within 6%.

극저주파 전자파와 암 발생 관련성에 관한 역학적 연구의 고찰

김윤신,조용성 漢陽大學校 環境 및 産業醫學硏究所 1998 環境과 産業醫學 Vol.7 No.1

Since Wertheimer and Leeper reported in 1979 that the incidence of cancer in children living near distribution is twice or three as high as normal, the association between leukemia or cancer and extremely-low-frequency(ELF) electric and magnetic fields(EMFs) has often been the subject of debate. Compared with the thermal effect of high frequency bands, the non-thermal effects of ELF-EMFs on animals are very weak and have been studied in the recent past. A positive correlation between low level ELF-EMFs and some specific cancer was detected by epidemiological studies but not directly by laboratory experiments. In 1990, the American Conference of Governmental Industrial Hygienists(ACGIH) published the threshold limit values(TLV) of ELF magnetic fields as a function of 60/f(frequency) mT while in 1993 the National Radiation Protection Board(NRPB of the UK) published 80/f mT safety guideline. These magnetic flux densities i.e. 1.0mT at 60Hz recommended values are 100 to 1,000 times higher than the flux density levels in our living environment, the suggested value that epidemiologists think has deleterious effects on humans is 0.2μT. It is difficult to decide which is the right guideline to adopt : the one suggested by the results of epidemiological surveys indicating that very low-level EMF raises the incidence of leukemia and other cancer, or the one which was recommended as the minimum level of magnetic flux density inducing a current that would supposedly affect humans and animals. Therefore this disparity between the values arrived at by epidemiological surveys and that recommended by regulatory agencies has to be resolved.

국내 전자파 위해 의사소통 프로그램에 관한 적용 사례연구

조용성,김윤신,전형진,김도경,이철민,홍승철,명성호,민석원 한국실내환경학회 2012 한국실내환경학회지 Vol.9 No.1

This case study carried out to improve the situation of large gap between scientific evidence and public perception on Extremely Low Frequency-Electric and Magnetic Fields (ELF-EMFs) problems in Korea. According to literature review on techniques and applications for EMF risk communication (RC) in Korea and other countries, the program which is appropriate for Korean society for RC was developed and the questionnaire to survey on perceptional level on ELF-EMFs based on this program was also developed. As some results of survey the perceptional levels on ELF-EMFs problems from some primary-school students and adults according to the educational tools (a presentation, a brochure, and a VOD) and protocols which were developed for RC, we identified in this study that the educational programs for RC have some effects to supply the right information and to improve the perceptional level on ELF-EMF problems to the general population such as the primary-school students and adults in Korea.

Extremely low‐frequency magnetic fields modulate nitric oxide signaling in rat brain

Cho, Sung In,Nam, Yun Sung,Chu, Li Ying,Lee, Jong Hyuk,Bang, Joon Seok,Kim, Hye Ryoun,Kim, Hyoung‐,Chun,Lee, Yu Jeung,Kim, Hyeong‐,Dong,Sul, Jung Duk,Kim, Daejin,Chung, Yoon Hee,Jeong, Ji Wiley Subscription Services, Inc., A Wiley Company 2012 BioElectroMagnetics Vol.33 No.7

<P><B>Abstract</B></P><P>Our previous study has shown that an extremely low‐frequency magnetic field (ELF‐MF) induces nitric oxide (NO) synthesis by Ca<SUP>2+</SUP>‐dependent NO synthase (NOS) in rat brain. The present study was designed to confirm that ELF‐MF affects neuronal NOS (nNOS) in several brain regions and to investigate the correlation between NO and nNOS activation. The exposure of rats to a 2 mT, 60 Hz ELF‐MF for 5 days resulted in increases of NO levels in parallel with cGMP elevations in the cerebral cortex, striatum, and hippocampus. Cresyl violet staining and electron microscopic evaluation revealed that there were no significant differences in the morphology and number of neurons in the cerebral cortex, striatum, and hippocampus. Differently, the numbers of nNOS‐immunoreactive (IR) neurons were significantly increased in those cerebral areas in ELF‐MF‐exposed rats. These data suggest that the increase in NO could be due to the increased expression and activation of nNOS in cells. Based on NO signaling in physiological and pathological states, ELF‐MF created by electric power systems may induce various physiological changes in modern life. Bioelectromagnetics 33:568–574, 2012. © 2012 Wiley Periodicals, Inc.</P>

극저주파 자기장의 소아백혈병 발생 위험 고찰

박동욱(Dong-Uk Park) 한국환경보건학회 2023 한국환경보건학회지 Vol.49 No.2

Background: The association between exposure to extremely low frequency-magnetic fields (ELF-MF) and childhood leukemia has been controversial. There is a need to clarify this relationship by summarizing key conclusions from systematic review articles. Objectives: The major aim of this study is to summarize key conclusions from systematic review articles on the association between exposure to ELF-MF and childhood leukemia based on childhood exposure to ELFMF, proximity from childhood household to high voltage cables, and parental occupational exposure to ELFMF. Methods: This study was conducted through a brief literature review focusing on systematic, meta-analysis, and pooled analysis methods. We conducted a literature search in PubMed using the key words “ELF-MF” and “childhood leukemia” singly or combined. Results: In 2002, the World Health Organization (WHO)’s International Agency for Research on Cancer (IARC) reviewed two manuscripts to conduct pooled analysis and concluded that there is a significant association between exposure to >0.3 μT or 0.4 μT and childhood leukemia. We found a total of four manuscripts for systematic or pool analysis that have been published since the IARC’s conclusion. They consistently concluded that there was a significant association between exposure to >0.4 μT and childhood leukemia compared to ELF-MF exposure to below 0.1 μT. The proximity of children’s households to high voltage cable lines and occupational exposure by their parents to ELF-MF during certain periods prior to or during pregnancy were inconsistently associated with childhood leukemia. The study found that many EU countries have implemented precautionary policies to prevent potential childhood leukemia due to exposure to ELF-MF. Conclusions: This study recommends implementing a precautionary policy that includes legal exposure limits for ELF-MF to minimize exposure to ELF-MF.

개인 노출량 조사를 통한 한국인의 극저주파 자기장 노출 수준

정준식,김근영,홍승철,조용성,김윤신,Jung, Joon-Sig,Kim, Keun-Young,Hong, Seung-Cheol,Cho, Yong-Sung,Kim, Yoon-Shin 한국환경보건학회 2012 한국환경보건학회지 Vol.38 No.1

Objectives: The purpose of this study was to estimate the exposure level to extremely low frequency-magnetic fields (ELF-MF) among a selected Korean population using 24-hour personal exposure measurement. Methods: Participants were randomly selected for the measurement of MF exposure under the assumption that the subjects are representative of the overall Korean population. Levels of personal exposure to MF were measured according to the subject's daily activities. Results: The 24-hour time-weighted average (TWA) of 250 participants was $1.56{\pm}4.56$ mG (GM, GSD: 0.79, 2.46 mG). Personal exposure levels for females were higher than for males. The highest personal exposure level was shown in the age group between 20-60 years old. Personal exposure levels according to job category were higher for the non-occupational group than for the occupational group. Conclusions: Our results showed MF exposure exceeding 2 mG per day among 11.3% of the Korean population, indicating a somewhat higher percentage compared to the EMF RAPID Program's results for the U.S population.