• Journal of Magnetics
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• v.20 no.3
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• pp.252-257
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• 2015

This paper investigates the concept and implementation of an energy harvesting device using a ferrofluid sloshing movement to generate an electromotive force (EMF). Ferrofluids are often applied to energy harvesting devices because they have both magnetic properties and fluidity, and they behave similarly to a soft ferromagnetic substance. In addition, a ferrofluid can change its shape freely and generate an EMF from small vibrations. The existing energy harvesting techniques, for example those using piezoelectric and thermoelectric devices, generate minimal electric power, as low as a few micro-watts. Through flow analysis of ferrofluids and examination of the magnetic circuit characteristics of the resultant electromagnetic system, an energy harvester model based on an electromagnetic field generated by a ferrofluid is developed and proposed. The feasibility of the proposed scheme is demonstrated and its EMF characteristics are discussed based on experimental data.

• Journal of Aerospace System Engineering
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• v.12 no.3
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• pp.64-69
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• 2018

The high-velocity electromagnetic forming (EMF) process is based on the Lorentz force and the energy of the magnetic field. The advantages of EMF include improved formability, wrinkle reduction, and non-contact forming. In this study, the electromagnetic-structural interlocking analysis was performed in order to analyze the moldability of aluminum pipe using electromagnetic molding. The magnetic flux density was decreased due to increasing electrical resistance as the temperature increased, and the stress-strain curve decreased. The higher the temperature, the lower the flow stress, increasing deformation.

• Journal of electromagnetic engineering and science
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• v.8 no.1
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• pp.23-27
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• 2008

Magnetic coupling delivering wireless power in capsular endoscope(CE) is described in this paper. The characteristic of the magnetic flux linkage coil which generates the induced electromotive force(emf) under the magnetic field was analyzed. With the analyzed results, a magnetic flux linkage coil system was developed and tested. It was confirmed that the magnetic flux linkage coil system could supply more than 50 mW power at 125 kHz without changing the structure of conventional CE.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.7
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• pp.733-740
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• 2013

The high-velocity electromagnetic forming (EMF) process is based on the Lorentz force and the energy of the magnetic field. The advantages of EMF include improved formability, wrinkle reduction, and non-contact forming. In this study, numerical simulations were conducted to determine the practical parameters for the EMF process. A 2-D axis-symmetric electromagnetic model was used, based on a spiral-type forming coil. In the numerical simulation, an RLC circuit was coupled to the spiral coil to measure various design parameters, such as the system input current and the electromagnetic force. The simulation results show that even though the input peak current levels were at the same level in each case, the forming condition varied due to differences in the frequency of the input current. Thus, the electromagnetic forming force was affected by the input current frequency, which in turn, determined the magnitude of the current density and the magnetic flux density.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.50 no.10
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• pp.464-471
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• 2001

Power utilities must satisfy both supplying high quality power economically and reducing EMF levels. In general, in order to reduce EMF levels from transmission line, it is effective to install shielding wires, configure wires with minimal space or modify structure of other conductors, etc., but these techniques require much cost and time. To some extent, the EMF levels associated with critical transmission lines can be reduced by redistributing the scheduled power generation, since it can change the power flows. There this technique can be readily applied without modifying other structures. This paper considers the OPF(Optimal Power Flow) with the EMF constraints in transmission lines to determine the power generation redistributions and demonstrates numerically the effectiveness of the approach.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.909-911
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• 2000

This paper introduce of program package for the numerical analysis of Electromagnetic field analysis using Finite Element Method, called Electro Magnetic Field(EMF). This software tool is developed by Changwon Nat'l Univ. cooperative with Hanyang Univ. and produced on a commercial scale. EMF has a simple, easy to use graphical interface which steps user through th problem setup, high accurate solution, and fast computation.

• 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.

• Journal of Magnetics
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• v.19 no.1
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• pp.84-89
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• 2014

This paper presents an analytical prediction and experimental verification of the electromagnetic performance of a parallel magnetized surface-mounted permanent magnet (SPM) motor having a fractional number of slots per pole combination. On the basis of a two-dimensional (2-D) polar coordinate system and a magnetic vector potential, analytical solutions for flux density produced by the permanent magnets (PMs) and stator windings are derived. Then, analytical solutions for back-electromotive force (emf) and electromagnetic torque are derived from these field solutions. The analytical results are thoroughly validated with 2-D nonlinear finite element (FE) analysis results. Finally, the experimental back-emf and electromagnetic torque measurements are presented to test the validity of the analysis.

• Proceedings of the KOSOMBE Conference
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• v.1996 no.11
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• pp.353-356
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• 1996

Early this year the construction of new high voltage power lines have been forced to stop due to the demonstration of residents in Kwa-chun. According to mutual agreement between the residents and Korea Electric Power Corporation, electromagnetic field(EMF) from present power lines was measured and EMF after completion of new power lines was estimated. The results show that EMF near power lines Is relatively low, and EMFnear electric substation is quite high due to the short distance between the power lines and ground. For 4 conduction 345kV line, magnetic field decreases to 3mG at the distance of 50m from the power line.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.05
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• pp.179-182
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• 1995

Although air, water, and noise pollutions have been widely recognized, electromagnetic forces(EMF) hazard has been rarely recognized as a pollution and very little studies has been done in this country. Thus, in this study electromagnetic forces radiated by various home appliances, once machines, and communication equipments were measured and so were several places radiating strong EMF such as subway stations and electric substations. Among the home appliances microwave oven senates lots of magnetic field and microwaves, and electric mattress does strong magnetic field. In video game room strong magnetic and considerable electric fields were measured. It was observed strong magnetic field inside of electric powered train and very strong magnetic and electric fields on some platforms. Hand-phone and car-phone radiate very hazardous level of microwaves to brain and that they rapidly come into wide use. In this study data base for various electric machines and places radiating strong EMFs were constructed and could be used for future epidemiological studies.