• Journal of the Korean Ceramic Society
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• v.34 no.5
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• pp.453-460
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• 1997

Sr-ferrite having magnetoplumbite structure is similar to Ba-ferrite in magnetic characteristics, but better magnetic characteristics for using motor application. To improve remanence magnetic flux density(Br) and coercive force(iHc), it is necessary that sintered ferrites must have high density and grain size less than 1 $\mu$m. By varying n values in SrO.nFe2O3 basic composition, calcination temperature, and BaO addition, Sr-ferrite powder and sintered specimen was prepared. The n values, calcination temperature, and BaO addition affected secondary phase formation, particle size, and particle shape. BaO addition enhanced Fe2O3 secondary phase and hexagonal shape particle. Fe2O3 phase reduced sintered density which greatly decreased Br.

• Journal of Electrical Engineering and Technology
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• v.7 no.3
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• pp.401-405
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• 2012

Current research about voltage leakage involves investigation of the effects of leaked voltage and current on humans through simulated environments and dummies. Electrocution results from leaked current when electricity flows through the body as a result of potential difference. Research that analyzes actual electrocution is insufficient because of the danger from leaked voltage present in the leakage area. This thesis analyzes magnetic flux density from current around a leak to investigate the distribution of current. The authors used a simulated environment to investigate electrocution accidents that frequently occur during floods through leakage along metal surfaces, and evaluated the distribution of leaked magnetic flux.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.3
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• pp.259-264
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• 2012

Automatic magnetic abrasive polishing (MAP), which can be applied after machining of a mold on a machine tool without unloading, is very effective for finishing a free-form surface such as a complicated injection mold. This study aimed to improve the efficiency of MAP of a non-ferrous mold surface. The magnetic array table and control of the electromagnet polarity were applied in the MAP of a free-form surface. In this study, first, the magnetic flux density on the mold surface was simulated to determine the optimal conditions for the polarity array. Then, the MAP efficiency for polishing a non-ferrous mold surface was estimated in terms of the change in the radius of curvature and the magnetic flux density. The most improved surface roughness was observed not only in the upward tool path but also in the working area of larger magnetic flux density.

• Journal of Biomedical Engineering Research
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• v.23 no.4
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• pp.269-279
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• 2002

When we inject a current into an electrically conducting subject such as a human body, voltage and current density distributions are formed inside the subject. The current density within the subject and injection current in the lead wires generate a magnetic field. This magnetic flux density within the subject distorts phase of spin-echo magnetic resonance images. In Magnetic Resonance Current Density Imaging (MRCDI) technique, we obtain internal magnetic flux density images and produce current density images from $\bigtriangledown{\times}B/\mu_\theta$. This internal information is used in Magnetic Resonance Electrical Impedance Tomography (MREIT) where we try to reconstruct a cross-sectional resistivity image of a subject. This paper describes numerical techniques of computing voltage. current density, and magnetic flux density within a subject due to an injection current. We use the Finite Element Method (FEM) and Biot-Savart law to calculate these variables from three-dimensional models with different internal resistivity distributions. The numerical analysis techniques described in this paper are used in the design of MRCDI experiments and also image reconstruction a1gorithms for MREIT.

• Journal of Welding and Joining
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• v.19 no.5
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• pp.526-533
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• 2001

Induction heating of float metal products has an increasing importance in many applications, because it generates the heat within workpiece itself and provides high power densities and productivity. In this study, the induction heating of a steel plate to simulate the line heating is investigated by means of the Finite Element Analysis of the magnetic field and temperature distribution. A numerical model is used to calculate temperature distribution within the steel plate during the induction heating with a specially designed inductor. The effects of materital properties depending on the temperature and magnetic field are taken into consideration in an iterative manner. The simulation results show good magnetic field with experimental data and provide good understanding of the process. Since the numerical model demonstrates to be suitable for analysis of induction heating process, the effects of air gap and frequency on magnetic-flux and power-density distribution are also investigated. It is revealed that these process parameters have an important roles on the electro-magnetic field and power-density distribution governing the temperature distribution of the plate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.2
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• pp.93-99
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• 1986

A longline is made of many snoods with baited hooks which are connected to mainline at constant intervals. Hauling the mainline, removing the unused baits and the hooked fish, and the arrangement of hooks are dependent on mainly manual labour as compared with mechanized other fishing gear in fishing operation. The mechanization for longline operation is needed in order to eliminate the manual handling and to shorten the labour time. The magnetic hook splitting apparatus which consists of the hook separator and the guide leading to storage magazine rail was devised for the mechanization of hauling operation. The experiments were carried out in order to measure the splitting rate of hooks in accordance with the hauling speed of mainline and magnetic flux density of splitting apparatus from February to November, 1985. The splitting rate was $94\%$ for the Alaska pollack (Theragra chalcogramma) hook and $96\%$ for the halibut (Paralichthys olivaceus) hook at the hauling speed 24 m/min and magnetic flux density 482 gauss. The unsplitting of hooks was caused by entangling snood in the mainline and low magnetic flux density. The rate is greater the faster hauling speed and the lower magnetic flux density, with an average of about $6\%$, The magnetic flux density needed to hook splitting becomes increased with the increasing hauling speed. When the practical hauling speed is from 20 to 35m/min, the magnetic flux density is needed from 400 to 850 gauss.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.2B no.4
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• pp.143-148
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• 2002

Up to now, DC-biased magnetic properties have been measured in one dimension (scalar). However, scalar magnetic properties are insufficient to clarify DC-biased magnetic properties because scalar magnetic properties can only impossibly consider the phase difference between the magnetic flux density B vector and the magnetic field strength H vector. Thus the magnetic field strength H and magnetic flux density B in magnetic materials must be directly measured as a vector quantity (two-dimensional). This paper presents measurement system to clarify the two-dimensional DC-biased magnetic properties.

• Journal of Power Electronics
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• v.19 no.3
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• pp.794-802
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• 2019

Magnetic geared motors are driven using the same operating principle as conventional synchronous motors in which a magnetic gear is embedded. The magnetic geared motor is structurally similar to a magnetic gear. However, by applying currents to the stator coil, the high-speed rotor is rotated by a magnetic field and the low-speed rotor is rotated according to the gear ratio. In this paper, the operational principle of a magnetic geared motor and the magnetic flux density in its inner and outer air gaps are described. Then the magnetic flux density in the two air gaps is used to express a method for calculating the electrical and mechanical output. Results obtained with the analytical calculation method are compared with those of the finite element analysis. Finally, a prototype is used to verify the results of the analytical calculation and FEA.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1029-1031
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• 2005

A magnetic position sensor is a apparatus that detect the rotating position by measuring the value of the flux density of the rotating position. In this paper, the magnetization system of the permanent magnet in the magnetic position sensor which detects the rotating position was designed. The permanent magnet was magnetized for the flux density into the hole element to be sinusoidal distribution according to the rotating position. To make the sinusoidal distribution of flux density, the magnetization values according to the position in permanent magnet were varied by adjusting the air gap between the pole of the magnetization fixture and the surface of the permanent magnet.

• Progress in Superconductivity and Cryogenics
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• v.9 no.3
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• pp.1-4
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• 2007

The current profiles in a coated conductor with transport current were calculated using an iterative inversion method from the data of the magnetic flux density profiles measured. The applied current was increased from 0 to 60 A by 10A step and decreased down to -60A by 20A step. The magnetic flux profiles were measured at a distance of 400 mm above the surface of the coated conductor using a scanning hall probe method. The current profiles calculated were very different from the Bean model: current density profile is not a constant in the critical region. However the aspect of the change of the current and magnetic flux density profiles in the case of decreasing applied current are similar to the theoretical calculations in Brandt's paper.