• The Transactions of the Korean Institute of Electrical Engineers C
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• v.51 no.10
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• pp.485-491
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• 2002

Since Wertheimer and Leeper reported possible adverse health effects of magnetic field in 1979, worldwide researches on this issue have been conducted. More recently, the U.S. Congress instructed the NIEHS (National Institute of Environmental Health Sciences), NIH (National Institute of Health) and DOE (Department of Energy) to direct and manage EMF RAPID (Electric and Magnetic Fields Research and Public Information Dissemination) program aimed at providing scientific evidence to clarify the potential for health risks from exposure to extremely low frequency electric and magnetic fields(ELF-EMF). Although they concluded that the scientific evidence suggesting adverse health risks of ELF-EMF is weak, the exposure to ELF-EMF cannot be recognized as entirely safe. Therefore, the purpose of this article is to describe magnetic field 3-D calculation and to evluate eddy current of human body compare to international guide line recognized one of the basic problems. In open boundary problem, Magnetic field using FEM is not advantageous in the point of the division of area and the proposition of the fictitious boundary. Therefore, we induced the analytic equation of magnetic field calculations so but the finite line segment based on Biot-Savarts law Also, Eddy currents induced due to ELF-EMF magnetic field are computed. To calculate induced currents, impedance method is used in this paper, An example model of human head with resolution of 1.27cm is used. In this paper, We evaluate the magnetic field and eddy current of human head around 765 kV transmission lines compare to international guide line.

• Journal of the Korean Society of Safety
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• v.8 no.3
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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 Ceramic Society
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• v.26 no.6
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• pp.802-810
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• 1989

The temperature dependence of piezoelectric strain constant and the electric field induced strain are investigated as a function of PT in 0.5[xPT-(1-x)PZ]-0.5PNN ceramics. The piezoelectric strain constant d31 has the highest value(360$\times$10-12m/V) at PT=0.68. The temperature dependence of d31 is improved as Curie temperature of sample is increased, and the electric field dependence of induced strain is decreased with the coercive field increased. This ceramic system shows both piezoelectric effect and electrostrictive effect under the applied electric field. The piezoelectric of tetragonal phase is higher than that of rhombohedral phase, and the magnitude of electrostrictive constant is appeared in the order of morphotropic, rhombohedral and tetragonal phase. The piezoelectric strain constant with applied field must be considered theelectrostrictive effect due to 90$^{\circ}$domain wall displacements, and the displacement of bimorph type actuator agrees with the calulated value well.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.189-189
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• 2009

This work was focused on the dielectrophoretic force of fullerenes dispersed in liquid crystal host medium, which are investigated in the homogeneously aligned liquid crystal (NLC) cells driven by external electric field. A fullerene of 10 wt% was doped into the LC medium and its electric field induced motion was controlled by both in-plane and vertical electric field. When the electric field was applied, the fullerene start to move in direction of applied electric field. The dark, grey and white states in the proposed device can be obtained by suitable combination of the polarity of applied electric field. The w and l are the width and distance between the electrodes. The reflectance at different l was measured and was found to be increased with increasing l. The dynamical motions of fullerene particles in LC medium suggest that fullerene can be designed for electronic-paper like displays.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.262-262
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• 2013

In surface chemistry area, many scientists studied the electrochemical reaction by changing work-function of metal; however, these methods had the weakness that it did not create the electric field. Unlike earlier studies, our capacitor-method makes a strong electric field in ice film. This electric field was induced by soft landing $Cs^+$ ions on ice film, and the strength was measured by the vibrational Stark shift of acetonitrile. In our system, the electric field strength is $10^9$ V/m and it is almost same in the electrochemical cell. This capacitor model provides new method to investigate the electrochemical reaction in vacuum system.

• Journal of ILASS-Korea
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• v.28 no.1
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• pp.24-31
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• 2023

In this study, characteristics of a propane-air premixed flame sin DC electric field was investigated. The stainless steel Bunsen burner and the stainless steel ring were used as electrode, and the high voltage supply was used for applying electric field. Flammability range increased significantly when the positive voltage was applied because of extension of LBO limit, while it shrank when the negative voltage was applied. The reason for this was not much related to the burning velocity, but the induced flow around the burner by electric field. withNOx production slightly increased after positive voltage was applied in identical equivalence ratio. Nevertheless, it was advantageous to apply the positive electric field to reduce the NOx since the extension of LBO limit makes the burner possible to operate in very low equivalence ratio.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.1206-1210
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• 2003

Effect of transverse electric field on crack kinking in ferroelectric ceramics subjected to purely electric loading is investigated. It is shown that the shape and size of the domain switching zone depends strongly on the direction of the applied electric field as well as the ratio of the transverse electric field to the coercive electric field. Under small-scale conditions, mode I and II stress intensity factors induced by ferroelectric domain switching are numerically obtained. The crack kinking in ferroelectrics is also discussed.

• Journal of Sensor Science and Technology
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• v.31 no.5
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• pp.330-336
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• 2022

This paper proposes a method to calibrate the electrode misplacement in underwater electric field sensor arrays (EFSAs) for accurate measurements of underwater electric field signatures. The electrode misplacement of an EFSA was estimated by measuring the electric field signatures generated by a known electric source and by comparing the measurements with the theoretical calculations under similar measurement conditions. When the EFSA measured the electric field signatures induced by an unknown electric source, the electric properties of the unknown electric source were approximated by considering the optimized estimation of the electrode misplacement of the EFSA. Finally, the measured electric field signatures were calibrated by calculating the theoretical electric field signatures to be measured with an ideally installed EFSA without electrode misplacement; the approximated electric properties of the unknown electric source were also taken into account. Simulations were conducted to test the proposed calibration method. The results showed that the electrode misplacement could be estimated. Further, the electric field measurements and the electric field-based localization of underwater vessels became more accurate after the application of the proposed calibration method. The proposed method will contribute to applications such as the detection and localization of underwater electric sources, which require accurate measurements of underwater electric field signatures.

• Journal of Magnetics
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• v.20 no.4
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• pp.450-459
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• 2015

In this paper, the safety distances and maximum permissible power (MPP) of resonant wireless power transfer systems are defined and derived with regard to human exposure to electromagnetic field (EMF). The definition is based on the calculated induced current density and electric field in the standard human model located between the transmitting and receiving coil. In order to avoid the adverse health effects such as stimulation of nerve tissues, the induced current and electric field must not exceed the basic restriction values specified in EMF safety guidelines. The different combinations of diameters of the coils and the distance between the two coils are investigated and their effects are analyzed. Two versions of EMF safety guidelines (ICNIRP 1998 and ICNIRP 2010) are used as bases for safety distance calculation and the difference between the two guidelines are discussed.

• The Korean Journal of Ceramics
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• v.7 no.1
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• pp.30-35
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• 2001

The contribution of the non-$180^{\circ}C$ domains to the electric-field-induced strains (EFI-strains) of PZT ceramics was evaluated by an XRD method and by an interferometric method. The XRD intensity ratio of 200 and 002 diffraction peaks of tetragonal PZT was measured under strong electric fields. The amount of the $90^{\circ}$ domain reorientation was evaluated and the strain due to the domain reorientation was calculated. It was confirmed that the EFI-strain of PZT ceramics was equal to the sum of the strain calculated from the d$_33$ constant determined by the resonance-antiresonance method and the strain due to the $90^{\circ}$ domain reorientation. The amount of the $90^{\circ}$domain reorientation has a linear relation with the c/a ratio in the "soft" PZT ceramics. A Mech-Zehnder interferometer was constructed to measure the EFI-strains vs. electric-field curves of PZT ceramics as a function of frequency. The EFI-strain vs. electric-field curve showed a hysteresis due to the effect of the non-$180^{\circ}$ domain reorientation when the applied voltage was high and its frequency was low. The apparent piezoelectric constant increased from the d$_33$ value determined by the resonance-antiresonance method with decreasing frequency. This deviation was attributed to the non-$180^{\circ}$ domain contribution.tribution.