• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.905-908
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• 2001

The microstructure and the magnetic properties of Mn-Zn ferrite, which were power loss and saturation magnetic flux density, were investigated as the function of the process before firing. The highest initial permeability and the lowest power loss were attained to the specimen with CaO 400 ppm as a resulted from the highest solubility to SiO$_2$and the creation of liquid phase which improved sintering. The biggest grain size, the highest saturation magnetic flux density and the lowest power loss, which was resulted from that the eddy current loss increased as grain size increased but the hysteresis loss much more decreased and the hysteresis loss strongly influenced on the total power loss rather than the eddy current loss, were obtained to the Mn-Zn ferrite added 2wt% PVA. The power loss was lowest and the saturation magnetic flux density was highest in case of 1 ton/$\textrm{cm}^2$ and the grain size was not influenced.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.10
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• pp.89-94
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• 2014

This paper presents a synchronous reluctance motor drive for maximum torque to current (MTC) considering magnetic saturation. Measured d-axis and q-axis inductances are used to obtain current angle vs. maximum torque curve using torque equation. Maximum torque to current control is achieved by the current angle and stator current for maximum torque from the current angle vs. maximum torque curve at a given torque reference.

• Journal of Magnetics
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• v.19 no.4
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• pp.404-410
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• 2014

This paper considers the design and performance evaluation of interior permanent magnet synchronous motors (IPMSMs). The initial design such as the sizing and shape design of the stator and rotor is performed for a given load condition. In particular, the equivalent magnetic circuit (EMC) is employed both to design the mechanical parameters of the rotor while considering nonlinear magnetic saturation effect and to analyze the magnetic characteristics of the air-gap of the motor. The designed motor is manufactured and tested to confirm the validity of the design processes and simulated results.

• Proceedings of the Korean Magnestics Society Conference
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• 2002.12a
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• pp.214-215
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• 2002

High saturation magnetization (B$\_$s/) and excellent high frequency characteristics of magnetic thin films has been recognized as the most important requirement for further miniaturization and higher frequency operation in magnetic devices, such as magnetic heads and magnetic sensors. Up to now, Fe-X-N (X =Ti, Hf, and Al etc.) films with B$\_$s/ of 15 ∼ 19 kG and coercivity (H$\_$c/) of 0.5 ∼ 5.0 Oe have been successfully fabricated and proven to satisfy various requirements as a potential candidate for thin film head materials. (omitted)

• Korean Journal of Metals and Materials
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• v.50 no.3
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• pp.248-255
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• 2012

AlN thin films containing various amounts of Co, AlN-Co, and Al-Co alloy particles were prepared using a two-facing-target type dc reactive sputtering (TFTS) system. The as-deposited films exhibited the variable nature expected from an AlN-rich phase, and an amorphous-like phase, depending on the Co content in the films. Specific favorable microstructures were prepared by optimizing annealing conditions. Those microstructures and their magnetic properties and resistivity were investigated. As-deposited films showed very small saturation magnetization and an amorphous-like structure. However, when annealed, the as-deposited amorphous-like phase decomposes into phases of AlN, Co and Al-Co. These annealing induced changes in the microstructure improve the magnetization and resistivity of the films. Further improvement of soft magnetic properties could lead to the material being used for high density magnetic recording head material.

• Journal of the Korean Society of Industry Convergence
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• v.17 no.3
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• pp.103-112
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• 2014

BY the Transformers and reactors, the input electrical energy is converted into magnetic energy. At the end through the magnetic energy was passed at the output parameter. Specially At the flyback transformer or a reactor airgap were designed to contain more magnetic energy. But that work is very difficult for the optimal design. It is that Contradictions are between the length of the Air-gap, Winding inductance, DC bias. As to e Several conflicting conditions in order to determine the optimum Air-gap has a lot of experience and trial & error is necessary. The approach proposed in this paper, the auxiliary winding on the core attached to part of primary core, that by applying a DC voltage has a dramatic effect like Core with designed Air-gap. This inventiveness and advantage is to regulate arbitrarily the Saturation Flux Quantity by the input signal to secondary winding. Accordingly obtained the biggest effect is that increasing limits of the saturation current destined by the material and shape of the conventional core. In other words, that can decreas the size of the transformer and reactor, While maintaining the current saturation capacity. This paper, prove its effect as using the local flux saturation in transformers and reactors for research by the computer program using the finite element method (FEM) simulation, followed by actual experiment to verify

• Journal of the Mineralogical Society of Korea
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• v.24 no.1
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• pp.31-36
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• 2011

Meteorites are extraterrestrial solid rock fragments that fell from the outer space. Investigating mineral magnetic properties of the Meteorites is essential in understanding the evolution of planets and asteroids in the Solar System. In particular, magnetic characterization of magnetic mineral can provide constraints on the progress of differentiation in ancient planetary bodies. In the present study, ratio of thermoremanent magnetization (TRM) over saturation isothermal remanent magnetization (SIRM) was applied to diagnose the magnetic minerals in meteorites and igneous rocks. Distinctive classification of TRM/SIRM suggests that kamacite, tetrataenite, magnetite, and (Cr,Ti)-rich iron oxide are responsible for the magnetization of H5 Richardton, LL6 St. Severin, ALH84001, and DaG476, respectively. The TRM/SIRM ratio could be an efficient tool in identifying magnetic minerals especially when rocks or meteorites contain unstable material under heating.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.821-827
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• 2010

This paper proposes a density method based topology optimization of a perpendicular magnetic recording system design in which the saturation effect is taken into account. During the topology optimization process in magnetic fields, the magnetic reluctivity is updated in accordance with the changes in element density determined by a sensitivity analysis. The magnetic reluctivity is determined from a B-H curve and is used to represent nonlinear material property, i.e., the saturation effect. The sensitivity for a generalized response functional is formulated using the adjoint variable method in which the nonlinear property is taken into account and the objective function is set such that the magnetic energy in the media is maximized. Effects due to the nonlinear property can be observed from a numerical study in which the linear and the nonlinear topology optimization results are compared.

• Journal of Power Electronics
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• v.14 no.2
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• pp.351-361
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• 2014

The discrete torque generation mechanism and inherently nonlinear magnetic characterization of switched reluctance motors lead to unacceptable torque ripples and limit the application of these motors. In this study, a phase current profiling technique and torque sharing function are proposed in consideration of magnetic saturation effects and by minimizing power loss in the commutation area between the adjacent phases. Constant torque trajectories are considered in incoming and outgoing phase current planes based on nonlinear T-i-theta curves obtained from experimental measurements. Optimum points on constant torque trajectories are selected by improving drive efficiency and minimizing copper loss in each rotor position. A novel analytic invertible function is introduced to express phase torque based on rotor position and its corresponding phase current. The optimization problem is solved by the proposed torque function, and optimum torque sharing functions are derived. A modification method is also introduced to enhance the torque ripple-free region based on simple logic rules. Compared with conventional torque sharing functions, the resultant reference current from the proposed method has less peak and effective values and exhibits lower copper loss. Experimental and simulation results from a four-phase 4 KW 8/6 SRM validate the effectiveness of the proposed method.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.552-555
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• 1995

The magnetic properties of Mg-Mn ferrites were investigated in the composition range of $Mg_{a}Mn_{b}Fe_{c}O_{4\pm\delta}$ (a+b+c=3) with the addition of $Al_{2}O_{3}$. In $MgO-MnO-Fe_{2}O_{3}$ ternary system, the spinel single phase existed within the composition range of MgO-50 mol%, MnO-70 mol% and $Fe_{2}O_{3}-60\;mol%$. The saturation magnetic flux density increased with the increase of $Fe_{2}O_{3}$ content and showed the maximum at the stoichiometric composition of $(Mg,Mn)Fe_{2}O_{4}$. In $Mg_{x}Mn_{1-x}Fe_{2}O_{4}(x=0.2~0.8)$ system, the saturation magnetic flux density showed the maximum at $Mg_{0.2}Mn_{0.8}Fe_{2}O_{4}$. The addition of $Al_{2}O_{3}$ resulted in the decrease of saturation magnetic flux density but increased the electrical resistivity.