• Journal of the Korean Magnetics Society
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• v.5 no.6
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• pp.963-967
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• 1995

Ultra thin layers of NiFeCo or NiFe were inserted at the interfaces of Ni and Cu to form a multilayer structure. In case of inserting a NiFe layer, the magnetoresistance was about 6%, the saturation magnetic field was 50 Oe and the hysteresis of R-H (resistance-magnetic field) was very small. In case of inserting a NiFeCo layer, the magnetoresistance increased to about 7% but the saturation magnetic field and hysteresis were also increased. The increase of the output under biased magnetic field was much larger in case of inserting a NiFe layer because of relatively smaller hysteresis in R-H behavior.

• Journal of Magnetics
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• v.18 no.1
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• pp.26-29
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• 2013

$Mn_xFe_{3-x}O_4$ powders have been fabricated by using sol-gel methods; their crystallographic and magnetic properties were investigated by using X-ray diffraction, scanning electron microscopy, M$\ddot{o}$ssbauer spectroscopy, and vibrating sample magnetometer. The $Mn_xFe_{3-x}O_4$ ferrite powders annealed at $500^{\circ}C$ had a single spinel structure regardless of the $Mn^{2+}$-doping amount and their lattice constants became larger as the $Mn^{2+}$ concentration was increased. Their Mossbauer spectra measured at room temperature were fitted with 2 Zeeman sextets due to the tetrahedral and octahedral sites of Fe ions, which made them ferrimagnetic. The magnetic behavior of $Mn_xFe_{3-x}O_4$ powders showed that the $Mn^{2+}$-doping amount made their saturation magnetization increase, but there were no severe effects on their coercivities. The saturation magnetization of the $Mn_xFe_{3-x}O_4$ powder varied from 38 emu/g to 70.0 emu/g and their minimum coercivity was 111.1 Oe.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.486-492
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• 1998

The amorphous Co-based magnetic films have a large saturation flux density, a low coercive force, and a zero magnetostriction constant. Therefore, they have been studied for application to magnetic recoding heads and micro magnetic devices. However, it was found that the magnetic anisotropy was changed for each film fabrication processes. In this study, we investigated how to control the anisotropy of sputtered amorphous $Co_{89}Nb{8.5}Zr{2.5}$ films. After deposition, the rotational field annealing ant the uniaxial field annealing were performed under the magnetic field of 1.5 kOe. the annealing was done at the temperature range from 400 to $600^{\circ}C$ for one hour. As-deposited amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin film had saturation magnetization ($4\piM_5$) of 0.8 T, coercive force($_IH_C$) of 1.5 Oe, and anisotropy field($H_k$) of 11 Oe. The amorphous $Co_{89}Nb{8.5}Zr{2.5}$ thin films annealed by rotational field annealing at $500^{\circ}C$ for one hour was found to be isotropy, and $4\piM_5$ of 0.9 T was obtained from these films, Also, the magnetic anisotropy of as-deposited films could be controlled by uniaxial field annealing at $400^{\circ}C$ for one hour. Anisotropy field($H_k$) of 17 Oe and $4\piM_5$ of 1.0 T were obtained by this method.

• Journal of Magnetics
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• v.18 no.2
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• pp.197-201
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• 2013

This paper presents the conversion parameter values of the magnetic properties of magnetic fluids. These values were determined for three magnetic fluid samples containing particles with diameters between 30 ${\AA}$ and 170 ${\AA}$. The factors that may affect the value of this parameter (size of particle, magnetic properties, the presence of clusters and aggregates) are also studied. The determined values for the conversion parameter (${\gamma}$) are between 0.25 and 0.76 and the determined limit value is 0.8. Because many applications require magnetic fluids with the saturation magnetization as high as possible and the viscosity as low as possible [1], it has been considered necessary to determine this parameter which describes the quality of magnetic fluids.

• Journal of Magnetics
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• v.22 no.1
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• pp.85-92
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• 2017

This research is proposed with the efficient searching method of deperming protocol for magnetic silence. The deperming protocol has been changed depending on the initial magnetic field, the final magnetic field, and the shot number, so deciding parameter is highly important. Therefore, in this paper, the value of the initial magnetic field is supposed to be fixed to that of the saturation field, and excluding the initial magnetic field in the variable, the deperming protocol has been analyzed depending on the final magnetic field and the change of the shot number. In the result of this experiment, the final magnetic field gets high performance to the reverse of the direction of the initial magnetization, and it is resulted that the shot number inverse proportion to the size of the final magnetic field.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.14-15
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• 2006

A saturation of magnetic flux in the core may occur when a large primary current flows when the iron-cored current transformer is used. This saturation makes the distorted secondary current of the CT. the distorted secondary current may cause the mal-operation or operation time delay of protective relays. CT compensation algorithm using The LSQ(Least Square) fitting method has a problem. It needs to acquire enough data for executing this algorithm without an error. In this paper, an enhanced algorithm using interpolation based LSQ(Least Square) Fitting Method is proposed. The Lagrange Interpolation Method is used for the interpolation and CT is simulated by EMTP. The results show that the proposed algorithm can accurately compensate a distorted secondary current more than existing Algorithm when the saturation severely occurs.

• Journal of Electrical Engineering and Technology
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• v.2 no.2
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• pp.241-248
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• 2007

The accuracy of all the schemes that belong to vector controlled induction machine drives is strongly affected by parameter variations. The aim of this paper is to examine iron losses and magnetic saturation effect in sensorless vector control of induction machines. At first, an approach to induction machine modelling and vector control scheme, which account for both iron loss and saturation, is presented. Then, a model reference adaptive system (MRAS) based speed estimator is developed. The speed estimation is modified in such a way that iron losses and the variation in the saturation level are compensated. Thus by substituting an artificial neural network flux estimator into the MRAS speed estimator. Experimental results are presented to verify the effectiveness of the proposed approach.

• Journal of Magnetics
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• v.18 no.2
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• pp.105-110
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• 2013

The design model and key parameters of the material design for the control of induced magnetic flux at the near-field and efficient power transfer in a modified wireless power transfer (WPT) system with a large air gap of wireless electric vehicles were investigated through analytical simulations for magnetic vector and time-domain transient analysis. Higher saturation magnetic core with low core loss induced a stronger vertical magnetic field by the W-type primary coil in the WPT system with a gap of 20 cm at 20 kHz, which is shown from the vector potentials of the magnetic induction. The transient analysis shows that the higher magnetic fluxes through the pick-up cores lead to a linear increment of the alternating voltage with a sinusoidal waveform in the non-contact energy transfer system.

• Journal of the Korean Vacuum Society
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• v.8 no.4A
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• pp.461-464
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• 1999

Planar type thin film inductors have a potential for the application of miniaturized DC-DC converters. For those high current applications, the magnetic film with high current capability is required. The current capability of magnetic films is mainly determined from high saturation magnetization (4$\piM_s$) as well as large anisotropy field $(H_k)$. We fabricated a double rectangular spiral thin film inductor which consist of magnetic layer, coil and insulator. Highest inductance values as well as best frequency characteristics can be obtained from 5 MHz and quality factor exhibit about 7.

• Journal of the Korean Magnetics Society
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• v.1 no.2
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• pp.85-88
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• 1991

A high sensitive magnetometer using piezoelectric torque sensor was built. The torque produced on the magnetizde sample with small oscillating magnetic field was measured by a piezoelectric sensor. The torque is proportional to the magnetization of the sample. Errors of the measurement for saturation magnetization remain less than 5 % compared to existing standard values.