• Title/Summary/Keyword: MF(magnetic fields)

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Investigation on Stray Magnetic Field of High-Speed Maglev

  • Sun, Yan;Lee, Chang-Young;Jo, Jeong-Min;Lee, Jin-Ho;Han, Young-Jae
    • Journal of international Conference on Electrical Machines and Systems
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    • v.3 no.1
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    • pp.27-31
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    • 2014
  • Magnetic fields (MF) generated both on board the vehicle and along the guideway provide levitation and propulsion forces. High speed maglev trains adopt electromagnet or superconducting magnet to realize levitation and propulsion functions. However, stray fields existing in passenger compartment and regions surrounding the vehicle and guideway have effect on passengers and environment. To investigate stray magnetic field effect, model of Transrapid and MLX are studied.

EFFECTS OF 50Hz CIRCULARLY POLARIZED MAGNETIC FIELDS ON SPONTANEOUS MAMMARY TUMORS IN RATS

  • Negishi, T.;Imai, S.;Shibuya, K.;Ltabashi, M.;Nishimura, I.;Sasano, T.
    • Proceedings of the Korea Electromagnetic Engineering Society Conference
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    • 1999.07a
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    • pp.173-186
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    • 1999
  • Several epidemiological studies have suggested that residential or occupational exposure to power frequency magnetic fields (MF) might increase the risk of cancer. The objective of this study is to elucidate the possible carcinogenic effects of MF exposure using female Sprague-Dawley (Crj:CD)rats. A total of 360rats was randomly divided into 6 groups of 60 rats each. Two groups were served as a negative control (vehicle: sesame oil only) or a positive control (single oral administration of 7, 12dimethylbenz(a)anthracene; DMBA, 90mg/kg body weight at 50-52days of age). Other four groups were simultaneously exposed to 0 (sham-exposed) 7, 70 or 350 $\mu$T(rms), continuous circularly polarized 50HzMF, 22 hrs/day, 7 days/weeks for 30weeks from 8weeks of age. Experiment was conducted under SPF condition and in a blinded manner, Ten animals in each grout were served as satellite animals and their several hormonal concentrations in sera, such as melatonin and prolactin, collected at the midnight were measured. In addition, complete histopathological examination were performed in other 50 animals per each group. In the positive control group, the first mammary nodule was palpated at the 7th weeks of experiment in 5 out of 59 animals. Afterward, the incidence of palpable mammary nodules increased steadily and reached at 76% and 98% of live animals at 14weeks and the end of experiment in sham and 350$\mu$ T-exposed groups were not significantly different from those in the sham-exposed and negative control groups. Histopathologocally, most of palpable nodules were mammary tumors. The incidences of animals with mammary tumors per animals survived ant the end of experiment were 4.1 and 100% in the negative and positive control groups, and 0.0, 6.0, 8.0 and 6.0% in the sham-, 7, 70and 350 $\mu$T-exposed groups, respectively. These incidences in three MF-exposed groups were not significantly different from those in both the sham- exposed and negative control groups. Based on these results, it was not supported that continuous circularly polarized 50 Hz magnetic fields at up to 350$\mu$T affect the incidence of spontaneous mammary tumors in female SD rats under the present experimental conditions.

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MAGNETIC FIELD IN THE LOCAL UNIVERSE AND THE PROPAGATION OF UHECRS

  • DOLAG KLAUS;GRASSO DARIO;SPRINGEL VOLKER;TKACHEV IGOR
    • Journal of The Korean Astronomical Society
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    • v.37 no.5
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    • pp.427-431
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    • 2004
  • We use simulations of large-scale structure formation to study the build-up of magnetic fields (MFs) in the intergalactic medium. Our basic assumption is that cosmological MFs grow in a magnetohy-drodynamical (MHD) amplification process driven by structure formation out of a magnetic seed field present at high redshift. This approach is motivated by previous simulations of the MFs in galaxy clusters which, under the same hypothesis that we adopt here, succeeded in reproducing Faraday rotation measurements (RMs) in clusters of galaxies. Our ACDM initial conditions for the dark matter density fluctuations have been statistically constrained by the observed large-scale density field within a sphere of 110 Mpc around the Milky Way, based on the IRAS 1.2-Jy all-sky redshift survey. As a result, the positions and masses of prominent galaxy clusters in our simulation coincide closely with their real counterparts in the Local Universe. We find excellent agreement between RMs of our simulated galaxy clusters and observational data. The improved numerical resolution of our simulations compared to previous work also allows us to study the MF in large-scale filaments, sheets and voids. By tracing the propagation of ultra high energy (UHE) protons in the simulated MF we construct full-sky maps of expected deflection angles of protons with arrival energies $E = 10^{20}\;eV$ and $4 {\times} 10^{19}\;eV$, respectively. Accounting only for the structures within 110 Mpc, we find that strong deflections are only produced if UHE protons cross galaxy clusters. The total area on the sky covered by these structures is however very small. Over still larger distances, multiple crossings of sheets and filaments may give rise to noticeable deflections over a significant fraction of the sky; the exact amount and angular distribution depends on the model adopted for the magnetic seed field. Based on our results we argue that over a large fraction of the sky the deflections are likely to remain smaller than the present experimental angular sensitivity. Therefore, we conclude that forthcoming air shower experiments should be able to locate sources of UHE protons and shed more light on the nature of cosmological MFs.

Estimation of ELF-MF Exposure Levels in the Korean Population through 24-Hour Personal Exposure (개인 노출량 조사를 통한 한국인의 극저주파 자기장 노출 수준)

  • Jung, Joon-Sig;Kim, Keun-Young;Hong, Seung-Cheol;Cho, Yong-Sung;Kim, Yoon-Shin
    • Journal of Environmental Health Sciences
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    • v.38 no.1
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    • pp.18-30
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    • 2012
  • 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.

A Study on the Extremely Low Frequency Magnetic Fields Exposure Characteristics of Workers in LCD Manufacturing Process (LCD 제조공정 종사근로자의 극저주파자기장 노출특성 연구)

  • Kim, JoonBeom;Kang, Joon Hyuk;Chung, Eun-Kyo;Jung, Kihyo
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.32 no.1
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    • pp.10-20
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    • 2022
  • Objectives: The aim of this study is to evaluate exposure levels of the extremely low frequency magnetic fields(ELF-MF) radiated from various electric facilities in Liquid Crystal Display(LCD) manufacturing processes. Methods: This study measured the exposure levels of personal and local ELF-MF for the electronic facilities installed in two LCD manufacturing companies. Samplers were installed around workers' waist during working hours to identify personal exposure levels, and direct reading equipment were located at 3 cm, 10 cm, and 30 cm away from the surface of the electronic facilities to measure local exposure levels. Average and maximum(ceiling) values were calculated for personal and local exposure levels. Results: Average and maximum of personal exposure levels for each worker were 0.56(mean) ± 0.02(SE) µT and 6.31 ± 0.75 µT, respectively. Statistical analyses of the study found that maximum of the personal exposure levels for engineers was significantly higher than that for operators since engineers spend more time near the electronic facilities for repairing. The range of maximum personal exposure levels was 0.50 ~ 43.50 µT and its highest level was equivalent to 4.35 % of ACGIH(American Conference of Governmental Industrial Hygienists) exposure limit value(1 mT). Maximum of local exposure levels was 8.18 ± 0.52 µT and the electronic facilities with higher exposure levels were roof rail and electric panel, which were not related to direct manufacturing. The range of maximum local exposure levels was 0.60 ~ 287.20 µT and its highest level was equivalent to 28.7 % of the ACGIH exposure limit value. Lastly, the local exposure levels significantly decreased as the measurement distance from the electronic facilities increased. Conclusions: Maximum of personal and local exposure levels did not exceed the exposure limit value of ACGIH. However, it is recommended to keep the workers as far as possible from the sources of ELF-MF.

A survey on the EMF Levels of Study and Electric Appliances in Korea (국내 전철 및 가전제품을 대상으로 한 전자장 수준 실태조사)

  • Jang, Seong Ki;Cho, Yong Sung;Lee, Seok Jo;Yoo, Seong Wha;Jung, Kyung Mi;Lim, Jun Ho
    • Journal of Korean Society of Occupational and Environmental Hygiene
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    • v.15 no.1
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    • pp.71-81
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    • 2005
  • The purposes of this study was to collect, analyze, and describe the MF exposure levels from subways in Korea and to measure and evaluate the MF levels generated from electric appliances used at general homes. The target subway lines were Seoul Metropolitan Line 1 to Line 8, Bundang Line, Incheon Line, Daegu Line, Gwangju Line, and Busan Line 1 and Line 2. We measured at each station in those subway lines and, all the train types (pantograph-equipped, motor-equipped, and common), and platform types(facing and isolating) were investigated by the distance(80, 200, 400 cm) from the train on 19 targeted subway lines using 3 magnetic field measuring devices (EMDEXII, Enertech Co.) during the survey from January till October, 2004. On the other hand, the levels of the 60Hz magnetic fields generated from 14 items of home electric appliances such as electric blankets, hair dryers, electric razors, etc. were measured at 10 general homes using 5 EMDEXII meters with a sampling interval of 1.5 second by the distance(surface, 30, 50, 100, 300cm ) from the target electric appliances. The survey results in the whole subway lines examined in this study were as follows; Seoul Metropolitan Line 4 using AC(alternating current) power source showed the highest mean value of $2.85{\mu}T$, followed by Seoul Metropolitan Line 1 running between Seoul and Incheon using AC($2.78{\mu}T$), Seoul Metropolitan Line 1 between Seoul and Uijongbu using AC($2.73{\mu}T$), Bundang Line using AC($1.79{\mu}T$), Seoul Metropolitan Line 1 connected from Yongsan using AC($1.67{\mu}T$), Seoul Metropolitan Line 1 between Seoul and Suwon using AC($0.79{\mu}T$), and so on. In general, the intensity of the magnetic field in the subway systems in Korea was significantly higher when using AC($2.14{\pm}0.91{\mu}T$) than when using DC($0.29{\pm}0.44{\mu}T$) power source. Among the home electric appliances examined, microwave ovens showed the highest mean value of $7.69{\mu}T$, followed by hair dryers($6.47{\mu}T$), vacuum cleaners($5.27{\mu}T$), televisions ($2.26{\mu}T$), electric blankets($1.38{\mu}T$), personal computers ($0.81{\mu}T$), and so on. Two items of electric appliances showed the excess value of $0.2{\mu}T$ at the distance of 30cm in the MF exposure level; electric razors $1.58{\pm}2.13{\mu}T$ and vacuum cleaners $0.48{\pm}0.44{\mu}T$. As a whole, this study showed a tendency that the shift of the MF levels according to the increase of distance from the electric appliances was lower than those of the results surveyed in UK and USA. As a result, this study is expected to suggest meaningful data for the future study in exposure assessment of magnetic fields and for the establishment of guidelines for subways and electric appliances in Korea. More detailed and large scaled exposure assessment studies should be performed continuously to get the various and useful information on health risk assessment of MFs in Korea.

Study on Standardization of the Environmental Impact Evaluation Method of Extremely Low Frequency Magnetic Fields near High Voltage Overhead Transmission Lines (고압 가공송전선로의 극저주파자기장 환경영향평가 방법 표준화에 관한 연구)

  • Park, Sung-Ae;Jung, Joonsig;Choi, Taebong;Jeong, Minjoo;Kim, Bu-Kyung;Lee, Jongchun
    • Journal of Environmental Impact Assessment
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    • v.27 no.6
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    • pp.658-673
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    • 2018
  • Social conflicts with extremely low frequency magnetic field(ELF-MF) exposures are expected to exacerbate due to continued increase in electric power demand and construction of high voltage transmission lines(HVTL). However, in current environmental impact assessment(EIA) act, specific guidelines have not been included concretely about EIA of ELF-MF. Therefore, this study conducted a standardization study on EIA method through case analysis, field measurement, and expert consultation of the EIA for the ELF-MF near HVTL which is the main cause of exposures. The status of the EIA of the ELF-MF and the problem to be improved are derived and the EIA method which can solve it is suggested. The main contents of the study is that the physical characteristics of the ELF-MF affected by distance and powerload should be considered at all stages of EIA(survey of the current situation - Prediction of the impacts - preparation of mitigation plan ? post EIA planning). Based on this study, we also suggested the 'Measurement method for extremely low frequency magnetic field on transmission line' and 'Table for extremely low frequency magnetic field measurement record on transmission line'. The results of this study can be applied to the EIA that minimizes the damage and conflict to the construction of transmission line and derives rational measures at the present time when the human hazard to long term exposure of the ELF-MF is unclear.

Study about Prediction Model to Extremely Low Frequency Magnetic Fields for the Selected Primary Schoolchildren Nearby High Voltage Power Line (고압 송전선로 주변에 위치한 초등학교 학생들의 극저주파 자기장 노출량 예측 모델에 관한 연구)

  • Kim, Yoon-Shin;Hyun, Youn-Joo;Choi, Seong-Ho;Roh, Young-Man;Hong, Seung-Cheol
    • Journal of Environmental Health Sciences
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    • v.32 no.5 s.92
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    • pp.506-514
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    • 2006
  • The objectives of this study were to evaluate personal exposure estimated using a time activity pattern and microenvironmental model. The study was carried out for 44 children attending a primary school nearby the lines (school A) and 125 children attending a school away from 154 kV power lines (school B). For children attending school A, the estimated personal level was a little weak correlated with the measured level($Pearson\;r\;=0.34{\sim}0.35$). For children attending school B, the correlation was very low ($Pearson\;r\;=\;0.09{\sim}0.16$) using the TW A Model II, otherwise, TWA Model II-I which considered the average residential MF level according to the distance from the power line and home explained $39{\sim}53%$ of the correlation in MF personal exposures. The estimated personal exposure level was very well represented by the measured exposure level using TWA Model II-2 which consisted on spot and 24 h stationary measurements at subject's home ($Pearson\;r\;=\;0.65{\sim}0.85$). In conclusion, personal magnetic field expsoure estimated using a TWA Model II-2 should be provided for a reasonable estimate of measured exposure in schoolchildren living near the power line.

Relationship Between Urinary Melatonin Levels and Extremely Low Frequency Magnetic Fields for the Selected Primary Schoolchildren Living Nearby and Away from Overhead Transmission Power Line (송전선로 주변과 비주변 초등학생을 대상으로 극저주파 자기장 노출과 뇨중 멜라토닌 분비량간의 상관성 연구)

  • Cho, Yong-Sung;Kim, Yoon-Shin;Lee, Jong-Tae;Hong, Seung-Cheol;Jang, Seong-Ki
    • Journal of Environmental Health Sciences
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    • v.30 no.3
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    • pp.191-206
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    • 2004
  • The present study investigated the hypothesis that a extremely low frequency magnetic field partially suppresses the synthesis of melatonin in a group of 28 primary schoolchildren living nearby and 60 primary schoolchildren aged 12 years living far away from overhead transmission power lines from December 2003 to April 2004 in Seoul, Korea. The mean personal exposure levels of the primary schoolchildren living nearby overhead transmission power line were 0.37 ${\mu}$T, whereas the value for the primary schoolchildren living away from overhead transmission power line 0.05 mT. From simple analyses, the mean melatonin levels in the primary schoolchildren living nearby were lower than away from overhead transmission power line, but not statistically significant differences in the levels of the melatonin (p=0.2421), whereas the statistically significant differences in the levels of the melatonin related to the distance from residence to power line less and more than 100 m by cut-off point (p=0.0139). In multiple linear regression analyses, distance from residence to power line (p=0.0146) and dietary habit about burned meat (p=0.0170) proved to be significant risk factors in the mean nocturnal melatonin levels in the primary schoolchildren. In conclusion, these results demonstrate that urinary levels of nocturnal melatonin are not altered in primary schoolchildren exposed to extremely low frequency magnetic field(ELF-MF) at overhead transmission power line.

Effect of Extremely Low Frequency Magnetic Fields on Gene Expression in Human Mammary Epithelial MCF10A Cells

  • Hong, Mi-Na;Lee, Hyung-Chul;Kim, Bong Cho;Lee, Yun-Sil;Gimm, Yoon-Myung;Myung, Sung-Ho;Lee, Jae-Seon
    • Journal of electromagnetic engineering and science
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    • v.12 no.4
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    • pp.271-279
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    • 2012
  • The effects of extremely low frequency magnetic fields (ELF-MFs) on physiological processes at the cellular level remain unclear despite a number of studies. To investigate the effects of ELF-MFs on gene expression, we exposed human mammary epithelial MCF10A cells to fields of 1 mT magnetic flux density at 60 Hz for 4 and 16 h and measured the transcriptional responses of 24,000 genes using Illumina microarrays. In three independent experiments, we found no statistically significant alteration of expression levels for any of the genes assayed using a cutoff value of 1.2-fold. To confirm this result, we selected six genes with trends suggesting possible expression level changes, although these trends were not statistically significant, and investigated their expression levels further using a semiquantitative reverse-transcription polymerase chain reaction. In three independent experiments, we did not find any alterations in the expression levels of these genes. From these results, we conclude that ELF-MFs do not affect gene expression profiles under our exposure conditions.