• The Transactions of the Korean Institute of Electrical Engineers C
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• v.48 no.5
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• pp.333-338
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• 1999

Thin film inductors of $10 mm \times 10 mm$ with inner coil type of 14 turns were fabricated by sputtering, photo-masking, and etching processes. Their characteristics of impedances and annealing after were investigated. The properties of impedances of the thin film magnetic core inductors with inner coil type were improved by magnetic field annealing due to the removal of residual stress and the improvement magnetic properties of magnetic films. But the characteristics of frequency of the thin film magnetic core inductors were not improved by magnetic field annealing due to properties of the spiral pattern and inner coil type. The thin film magnetic core inductor annealed by uniaxal field annealing method showed an inductance of 1000 nH and resistance of$ 6 \Omega$ of 1 at 2 MHz.

• Transactions on Electrical and Electronic Materials
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• v.1 no.3
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• pp.29-33
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• 2000

The crystallographic and high frequency characteristics of $Fe_{73.9}Cu_{1.0}Nb_{3.5}Si_{14.0}B_{7.6}$ soft magnetic alloys were investigated under magnetic field annealing, The crystallization fraction of annealed samples with longitudinal magnetic fields is higher than that of samples without magnetic field. When the transverse magnetic field is applied, the crystallization fraction does not increases but decreases until $500^{circ}C$. It is found that for samples, the saturation induction are all same with 1.3 T. The coercive field of as-cast samples is 1.03 A/cm, but in annealed samples it decrease from 0.56 to 0.1A/cm with increasing annealing temperature from 400 to $550^{circ}C$. The squareness of annealed samples under transverse magnetic field has a small value than that of both without field and with longitudinal field annealing. It is noted that the magnetic field annealing with transverse direction to amorphous $Fe_{73.9}Cu_{1.0}Nb_{3.5}Si_{14.0}B_{7.6}$ profoundly influenced on the Mossbauer spectra in contrast to that with longitudinal direction and without magnetic field.

• 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.

• Applied Microscopy
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• v.47 no.1
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• pp.29-35
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• 2017

Transverse magnetic field annealing (TFA) was carried out on $Fe_{73.5}Cu_1Nb_3Si_{15.5}B_7$ nano-crystalline magnetic core with the aim at decreasing coercivity ($H_c$) while keeping high inductance ($L_s$). The magnetic field generated by direct current (DC) was applied on the magnetic core during different selected annealing stages and it was proved that the nanocrystalline magnetic core achieved lowest $H_c$ when applying transverse field during the whole annealing process (TFA1). Although the microstructure and crystallization degree of the nanocrystalline magnetic core exhibited no obvious difference after TFA1 compared to no field annealing, the TFA1 sample showed a more uniform nanostructure with a smaller mean square deviation of grain size distribution. $H_c$ of the nanocrystalline magnetic core annealed under TFA1 decreased along with the increasing magnetic field. As a result, the certain size nanocrystalline magnetic core with low $H_c$ of 0.6 A/m, low core loss (W at 20 kHz) of 1.6 W/kg under flux density of 0.2 T and high $L_s$ of $13.8{\mu}H$ were obtained after TFA1 with the DC intensity of 140 A. The combination of high $L_s$ with excellent magnetic properties promised this nanocrystalline alloy an outstanding economical application in high frequency transformers.

• Journal of Magnetics
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• v.7 no.2
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• pp.45-50
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• 2002

A magnetic field annealing is firstly used for nanostructured Sm-Co/Co films, prepared by magnetron sputtering method. The effects of magnetic field annealing on single-layered Sm-Co films are different from those on multi-layered Sm-Co/Co films. A detailed analysis of microstructures and magnetic properties is made by means of HRTEM, Auger electron spectroscopy, XRD and Physical Property Measurement System (PPMS). From magnetic properties and microstructure analysis, it was confirmed that these differences originate from the effects of magnetic field annealing on crystallization behavior of the films. The relationship between magnetic properties and microstructures explains a different demagnetization process of single-layered and multilayered films. For the single-layered Sm-Co films, magnetic-field-annealing makes the main phases change from $CaCu_5/ to Zn_2Th_{17}$ structure, resulting in a decrease of coercivity. The results show that the magnetic-field-annealing is useful to improve the properties of nanostructured Sm-Co(30 nm)/Co(10 nm) films, which ascribe to improving the pinning effectiveness in coercivity mechanism and decreasing the magnetostatic interaction of films. A very high coercivity about 0.7 T was obtained from nanoscaled multi-layered Sm-Co(30 nm)-/Co(10 nm) films.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.150-153
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• 1994

Magnetic field annealing method has been used to obtain proper hysteresis loop shapes which are useful to a device using amorphous ribbon. In this study, two pairs of Helmhotz coils were used to apply longitudinal and transverse magnetic field during annealing. For the measurement of coercive field strength noise which depends on magnetic field annealing, Co-based amorphous alloy ribbon $VITROVAC^{\circledR}$ 6030 was used. For the sample which was annealed under dc transverse and dc longitudinal magnetic field, coercive field strength noise was nearly independent of magnetizing frequency ranging from 1 to 100 kHz, but dc transverse and ac longitudinal magnetic fields annealed samples show that the coercive field strength noise decreased in power of magnetizing frequency. When magnetic domain nucleation occurred, the coercive field strength noise increased remarkably and decreased in power of magnetizing frequency.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.59-72
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• 1999

In this thesis, we measured the Barkhausen effect of CoFeSiB amorphous ribbon and then investigated its possibility to be used as a sensor material. We used a sample of composition $($Fe_{0.06}$$Co_{0.94}$)_${0.79}$$Si_{2.1}$$B_{18.9}$ with a thickness 12[pm1, width 2.5[rnml and length 5[cm], which was fabricated by a single roll method. In order to improve magnetic characteristics of the sample, we had carried on annealing in the magnetic field and in none magnetic field. And, experimented results to the magnetic characteristics show that the ribbon has large Barkhausen jump even in weak magnetic field below 0.5[0el. From the results, we confirmed that the sample can be used as an magnetic sensor material.

• Proceedings of the KIEE Conference
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• 1996.07a
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• pp.193-195
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• 1996

In amorphous transformer core, magnetic field annealing is required for inducing uniaxial magnetic anisotropy to circular direction of the core. Generally annealing temperature is about foot, so insulator using in solenoid bed must have a high temperature stability, mechanical strength and good machinability. In this study, we made the magnetic field annealing apparatus using insulators, conductors, connectors and power supply. And then tested the apparatus in annealing process of 50 kVA amorphous transformers.

• Journal of the Korean Magnetics Society
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• v.11 no.4
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• pp.173-178
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• 2001

The effects of heat-treatment with magnetic or non-magnetic field on magnetic properties of gas-atomized MPP dust cores subjected to various cooling processes after annealing were investigated. Upon magnetic-field annealing, ac permeability and core loss decreased with the increase of cooling rate, which were attributed to the generation of inhomogeneous internal stress and anomalous eddy current loss, respectively. It was not observed the formation of ordered phase and the related change in magnetic properties at the cooling stage for MPP dust cores. In MPP alloys, magnetic anisotropy was easily induced through the directional order, and permeability and core loss were changed under the conditions of low cooling rate and magnetic annealing.

• Transactions on Electrical and Electronic Materials
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• v.8 no.1
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• pp.32-35
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• 2007

In this article, a novel annealing technique using alternating magnetic field (AMF) is adopted to improve the electrical characteristics of pentacene film, thereby enhancing the performance of pentacene-based organic thin film transistors (OTFTs). According to the investigation results, the electrical conductivity in the pentacene film could be increased from 0.32 to 1.18 S/cm by annealing the pentacene film using AMF. And also, OTFTs with the pentacene film annealed by AMF exhibited an improved performance compared to the device without annealing. These results suggest that an annealing using AMF can be an effective method to improve the performance of devices based on organic semiconductors.