• Journal of Magnetics
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• v.15 no.3
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• pp.108-111
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• 2010

Fe50Cr50 metastable alloys were prepared by the mechanical alloying method with milling periods of 1, 2, 4, 6, 12 and 24 hours, respectively. The structural evolution was analyzed by the extended x-ray absorption fine structure (EXAFS). In this work, the EXAFS analysis provided the local structural information around Fe central atom. The saturation magnetization was also measured by VSM. The magnetization decreased as the process mechanical alloying progressed. The magnetic property was related to the local structural variation as a function of processing time. The analysis showed that the diffusion Cr atoms into Fe clusters caused the reduction of magnetization. EXAFS analysis exhibited that the local ordering of magnetic atoms caused the magnetic ordering. Also, EXAFS analysis showed that the long range order of Fe atoms was destroyed completely in 24 hour milling.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.12
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• pp.1725-1731
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• 2017

In hysteresis simulation, the Preisach model is most widely used as the reliability. However, since the first-order transition curves used in the conventional Preisach model are very inconvenient for actual measurement, many researches have been made to simplify them. In this study, the minor loops obtained along the initial magnetization curve are used to obtain the Everett function used in the Preisach model. In other words, The Everett table is constructed by using the minor loops, and are applied to the magnetization dependent Preisach model to reconstruct the Everett table. In order to minimize the error, the spline interpolation method is used to complete the final Everett table and the hysteresis loop simulation is performed with the Everett table. Furthermore, it is applied to the inductor analysis to perform not only sinusoidal wave and square wave drive but also PWM wave drive considering hysteresis. The validity of the proposed method is confirmed by comparison with simulation and experiment.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.12
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• pp.2116-2121
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• 2007

Numerical identification of synthetic d-q flux linkage, representative parameters for analyzing interior buried PM synchronous Motor(IPMSM) with distinguished magnetic saturation, has been peformed. Particularly, numerical identification of synthetic flux linkage using modified Finite Element Method(F.E.M) has been taken cross-magnetization of multi-layered PM configuration into consideration. Futhermore, experimental identification on the purpose-built prototype has been made to verify the validity of the numerically identified synthetic d-q flux linkages.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.900-904
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• 1995

We have developed a new torque magnetometric method for measuring the M-H hysteresis loop of a spheroid-shape magnetic material having a uniaxial anisotropy. Our torque magnetometric method gives the saturation magnetization as well as the remnant magnetization, simultaneously. A torque magnetometer having the torque sensitivity of $10^{-6}$ dyn cm could give the extreamly high sensitivity of $10^{-9}$ emu in measuring the magnetic moment, which is high enough to measure the magnetic moment of a monolayer Ni film. The accuracy of the present method was negligibly affected even at the applied fields near the coercivity where magnetization was inhomogeneous.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.6
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• pp.255-262
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• 2001

This paper deals with characteristic analysis method of the slotless type Permanent Magnet Linear Synchronous Motor(PMLSM) using the space harmonic method. Analysis models of the PM and the armature current are described by the magnetization configurations taking into account the 2D and 3D distribution. In 3D analysis, the thrust and normal force can be calculated more accurately, because it can consider the z component flux density which is impossible in 2D analysis. In order to verify the validity of the proposed method, the results of the analytic method are compared with not only the experimental ones but ones of Finite Element Method(FEM).

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.11
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• pp.729-736
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• 2000

This paper deals with the characteristic analysis of magnetizer for convergence purity magnet by the finite element method. The analysis utilizes combined method of the time-stepped finite element analysis and the Preisach model with hysteresis phenomena. In the finite element analysis, the non-linearity and the eddy current of the magnetizing fixure and permanent-magnet are taken account. The magnetization distribution in the permanent magnet is determined by using Preisach model which are composed of Everett function table and the first order transition curves is obtained by the Vibrating Sample Magnetometer. The calculated flux density values on the surface of the permanent magnet are led to the approximated gauss density values measured by the gauss meter. As a result, winding current, copper loss, eddy current loss of the magnetizing yoke, flux plot, surface gauss plot, temperature rise of the coil and resistor variation, vector diagram of magnetization distribution are shown.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.983-984
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• 2007

The spindle motor used on the ODD has a characteristic that electromagnetic pulsation and noise change differently by magnetization pattern of rotor. Therefore, design of magnetizer yoke that make to have optimal magnetization pattern is very important. In this paper, we proposed an analysis method that applies magnetizer analysis result to the spindle motor. We measured back-EMF of the real spindle motor. And then, we verified validity of the proposed analysis method by comparing the measurement and analysis result. Also, we designed the magnetizer shape that has optimal magnetization pattern by using proposed method. As a result, we reduced cogging torque of the spindle motor.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.4
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• pp.251-257
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• 2023

This study entailed an investigation of a tensile stress measurement method for prestressed concrete (PSC) tendons by utilizing external magnetization. The target of this study are PS structures that have been constructed and in use. An optimal external magnetization based elasto-magnetic (EM) sensor was designed using finite element analysis considering various factors, such as coil arrangement and size, that could influence the PS tendons inside the PSC girder. The residual tensile stress resulting from the external magnetization of the girder was then determined. Further, theoretical verification was performed using the numerical and material data used in the finite element analysis for sensor design. The calculated values of strength of magnetization at the target location were matched with the finite element analysis results. Thus, the designed sensor and the feasibility of magnetizing the tendons inside the PSC I-girder using an EM sensor were validated.

• Geophysics and Geophysical Exploration
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• v.27 no.2
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• pp.119-128
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• 2024

Marine magnetic surveys provide a rapid and cost-effective method for pioneer geophysical survey for many purposes. Sea-surface magnetometers offer high accuracy but are limited to measuring the scalar total magnetic field and require dedicated cruise missions. Shipboard three-component magnetometers, on the other hand, can collect vector three components and applicable to any cruise missions. However, correcting for the ship's magnetic field, particularly viscous magnetization, still remains a challenge. This study proposes a new additional correction method for ship's viscous magnetization effect in vector data acquired by shipboard three-component magnetometer. This method utilizes magnetic data collected simultaneously with a sea-surface magnetometer providing total magnetic field measurements. Our method significantly reduces deviations between the two datasets, resulting in corrected vector anomalies with errors as low as 7-25 nT. These tiny errors are possibly caused by the vector magnetic anomaly and its related viscous magnetization. This method is expected to significantly improve the accuracy of shipborne magnetic surveys by providing corrected vector components. This will enhance magnetic interpretations and might be useful for understanding plate tectonics, geological structures, hydrothermal deposits, and more.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.4
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• pp.415-421
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• 2015

This paper describes the study of the design procedure for the step-by-step setup parameters and of the magnetizing method for performance and size reduction in the development of a haptic vibrator. The study of magnetization was accomplished by comparing the electromagnetic force in accordance with the horizontal and the vertical magnetization. The theoretical results indicated that the horizontal magnetization resulted in a better performance. The systematic design of a step-by-step procedure for establishing the design parameters was verified by testing the characteristics of the fabricated prototype product. The vibration response function analysis and electric field analysis were processed by decoupling of the analytical method, and these were determined to be in good agreement with the test results. The design parameters to contributing to the product reliability included the spring height, the welding position, and the coil position. The sensitivity of the electromagnetic field and the performance change were analyzed based on the design parameters. As a result, we proposed a design method to implement a reliability-based, high performance haptic vibrator.