• The Korean Journal of Physiology and Pharmacology
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• 제14권6호
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• pp.427-433
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• 2010

This study was conducted to investigate the effects of extremely low frequency electromagnetic fields (EMF) on signal pathway in plasma membrane of cultured cells (RAW 264.7 cells and RBL 2H3 cells), by measuring the activity of phospholipase $A_2$ ($PLA_2$), phospholipase C (PLC) and phospholipase D (PLD). The cells were exposed to the EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h. The basal and $0.5\;{\mu}M$ melittin-induced arachidonic acid release was not affected by EMF in both cells. In cell-free $PLA_2$ assay, we failed to observe tbe change of $cPLA_2$ and $sPLA_2$ activity. Also both PLC and PLD activities did not show any change in the two cell lines exposed to EMF. This study suggests that the exposure condition of EMF (60 Hz, 0.1 or 1 mT) which is 2.4 fold higher than the limit of occupational exposure does not induce phospholipases-associated signal pathway in RAW 264.7 cells and RBL 2H3 cells.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• 제24권4호
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• pp.509-517
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• 2014

Objectives: This study was conducted to investigate the patterns of exposure of welders to strong magnetic fields for extended periods of time on the basis of their daily activities as recorded in a logbook. Methods: Male workers whose main job is welding, specifically seven welders occupied with gas tungsten arc welding(GTAW), two performing shielded metal arc welding(SMAW), and ten engaged in gas metal arc welding(GMAW), were measured in terms of the degree to which they were exposed to extremely low frequency(ELF) magnetic fields over 24 hours by using an electromagnetic field meter(EMF meter), as well as based on a daily activity log. Results: The welders were exposed to $1.25{\pm}4.95{\mu}T$ of magnetic field per day on average. For those who spent more than half a day-735.26 minutes, or 51.1% of the day-at work, the figure averages $3.88{\pm}8.85{\mu}T$ with a maximum value of $221.28{\mu}T$. The subject welders spent $338.14{\pm}154.95$ minutes per day at home. During their stays at home, they were exposed to an average of $0.17{\pm}0.06{\mu}T$ with a maximum value of $3.50{\mu}T$. The maximum exposure of $221.28{\mu}T$ occurred when welders performed GMAW. The average exposure reached its highest at $17.71{\pm}6.96{\mu}T$ when conducting SMAW. Magnetic field exposure also depends upon posture: welders who sat while welding were exposed five times more than those who stood during work, and this difference is statistically significant. As for the relationship between distance from the welding power supply and maximum magnetic field exposure, maximum magnetic field exposure decreases as the distance increases. The average magnetic field exposure, in the meantime, showed no significant difference depending on distance. Conclusions: The following were observed through this study: 1) welders, while conducting jobs, are exposed to magnetic fields not only from the welding machine, but also from the surrounding base material due to the current flowing between the welding machine and base material, meaning that they are continuously exposed to a magnetic field; and 2) welders are more exposed to magnetic fields while they sit at a job compared to when they stand up.

• Journal of the Korean Society of Safety
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• 제8권3호
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• pp.34-43
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• 1993

This paper presents a study on the characteristics and safety criteria for human body in ELF (Extremely Low Frequency : 50-60Hz) electric and magnetic fields. Many researches for ELF electric and magnetic fields, which are developed in the past, are studied and analyzed In this paper. In order to estabilish the safety criteria for human body in the field, the field intensity, induced current and voltage are calculated by the electrostatic field approach which is far simpler than the electromagnetic field one based on Maxwell equation. The method is applied to the 345 KV transmission line system In operation and 765 KV system under consideration. According to the results, the maximum value of field intensity, 6.8627KV/m, is evaluated at the location which is 14m away from transmission line. As the safety criteria value by the abroad researches asserting that the human can detect the Induced current in 6KV/m and above, 5KV/m and 7KV/m are recommended at residence area and nonresidence area, respectively.

• Journal of the Korean Society of Safety
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• 제11권3호
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• pp.89-96
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• 1996

This paper presents a study on the analysis and evaluation for ELF( Extremely Low Frequency) electric and magnetic fields under the transmission line according to the power system states. The power system states are classified into two types, normal state resulting from normal operation and alert state from outages. The current in a system is changed continually owing to the load fluctuations even in a normal operation. To calculate the current of the concerned line in a normal state, the system load level is devided into light, base and heavy load level. In case of contingency, an efficient algorithm based on matrix inversion lemma is developed to figure out the current changes. In order to analyze the variations of ELF field caused by the current fluctuations the electrostatic field approach which is far simpler than the electromagnetic field one based on Maxwell equation is introduced in this paper. The suggested method is applied to the IEEE 14 bus system to demonstrate the usefulness.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제14권8호
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• pp.871-877
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• 2003

In this paper, the design parameters for the magnetic field source at extremely low frequency are proposed. This facility can be used fur in vivo experiments with small animals to investigate biological response to the driving magnetic fields. In case that the exposed animals are motionless, the animals may be affected by the directivity of driving field. To avoid this effect, a 2-axis ELF magnetic field driving apparatus was designed. The optimum location and number of turns of each coil were obtained by numerical analysis. Applying these data to the MATLAB code(for computation), the magnetic field distribution was obtained. The calculation result fur a well-designed facility showed that the space in which the amplitude of the magnetic field lies within the 95 % of the magnetic field distribution was more than 60 % of each axis length.

• Proceedings of the Korea Environmental Mutagen Society Conference
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• 한국환경성돌연변이발암원학회 2004년도 KSOT/KEMS Fall Annual Meeting
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• pp.167-167
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• 2004

• Korean Journal of Clinical Laboratory Science
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• 제37권3호
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• pp.220-227
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• 2005

Recently, the use of an electrical apparatus has brought up concerns of health risks from exposure to electromagnetic fields. EMF is composed of electric fields and magnetic fields. Heavy exposure to EMF can occur only in the vicinity of high-voltage overhead transmission lines, close to transformers and underground cables, and also close to large electrical machinery. In this thesis I have investigated the hypothesis of the correlation between occupational exposure to ELF-EMF and the risks of leukemia, anemia, cancer. Therefore, the aim of this study is to investigate whether or not ELF-EMF emitted from electric power stations and transformer substations affect some hematological parameters and tumor markers of electric utility workers. The hematological test results and tumor markers under investigation were similar in the two groups but some of parameters such as RBC, AFP, LDH showed significant difference between the two groups from two sample t-test (p<0.05). The exposure group showed increased LDH level compared to the control group by two sample t-tests. In addition, the abnormal LDH level in the exposure group was observed to be clinically significant by ${\chi}^2$-test. However, the levels of RBC, AFP observed were not clinically significant by ${\chi}^2$-test (p>0.05). These results suggested that ELF-EMF does not affect most blood test parameters except LDH of electric utility workers.

• Journal of Environmental Health Sciences
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• 제23권1호
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• pp.55-61
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• 1997

This study was executed for the purpose of investigation of the EMFs exposures of personal and electronic environment. This study examines ELF-EMFs of electric appliances, subways and occupational and non-occupational human exposures, using EMDEX II (for 40 - 800Hz, Enertech Consultant, Inc.), from October 1995 to March 1996. Among the electric appliances examined, a massage unit showed the highest mean value of 247.07 $\mu$T, followed by an electric blanket of 5.24 $\mu$T. Indoor levels of EMF in subways exceerlcd 0.2 $\mu$T of the Swedish Guideline. The mean personal exposure levels of occupational group were 0.18 $\mu$T, while the personal EMF level of non-occupational group were 0.07 $\mu$T. Occupational group were exposed more highly while at work. However, the EMF levels during nonwork and sleep exposures between occuptional group and nonoccupational group were about the same. Estimates of time-intergrated exposure indicated that utility-specipic job classifications received about one-half or more of their total exposure on the job. Finally, this study would provide significant data for future research for exposure to magnetic fields, and more detailed study and research are necessary.

• The Korean Journal of Physiology and Pharmacology
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• 제15권5호
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• pp.313-317
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• 2011

The effects of extremely low frequency electromagnetic fields (EMF) on intracellular $Ca^{2+}$ mobilization and cellular function in RBL 2H3 cells were investigated. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not produce any cytotoxic effects in RBL 2H3 cells. Melittin, ionomycin and thapsigargin each dose-dependently increased the intracellular $Ca^{2+}$ concentration. The increase of intracellular $Ca^{2+}$ induced by these three agents was not affected by exposure to EMF (60 Hz, 1 mT) for 4 or 16 h in RBL 2H3 cells. To investigate the effect of EMF on exocytosis, we measured beta-hexosaminidase release in RBL 2H3 cells. Basal release of beta-hexosaminidase was $12.3{\pm}2.3%$ in RBL 2H3 cells. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not affect the basal or $1{\mu}m$ melittin-induced beta-hexosaminidase release in RBL 2H3 cells. This study suggests that exposure to EMF (60 Hz, 0.1 or 1 mT), which is the limit of occupational exposure, has no influence on intracellular $Ca^{2+}$ mobilization and cellular function in RBL 2H3 cells.

• Economic and Environmental Geology
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• 제21권3호
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• pp.277-285
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• 1988

The ELF-MT survey has been conducted at 9 points along the national road between the Sindangri and Dojonri area to study on the boundary between the Okchon and Choson systems, and subsurface geological structure of these two systems. Natural electromagnetic fields of 7.8, 14, and 20 Hz in the Schumann resonant frequency band were used for ELF-MT measurement. Apparent resistivity values were calculated from the measured magnetic and electric fields at each frequency, and resistivity sections were obtained by means of a trial and error method for one-dimensional analysis and finite element method for two-dimensioal analysis. The results of this study show that the resistivities of the Okchon and Choson systems are 700-3500 ohm-m and 40-5000 ohm-m, respectively. The boundary between these two systems is a fault with the width of 1 km fault zone and resistivity value of 200 ohm-m, and is located around Koburangjae. Another fault is appeared in Sindangri, and its resistivity value is 130 ohm-m. Intrusion of biotite granite is distributed in Jungchijae, and its resistivity value is 750 ohm-m. The area between Susanri and Koburangjae shows the highest resistivity value of 3500 ohm-m because metabasite and amphibolite are distributed in that area. Extremely low resistivity value of 40 ohm-m around Yongamsan is due to the Yongam formation, which is composed of graphitic black slate and overlying Choson Great Limestone group.