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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Journal of the Korean Magnetics Society
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Journal DOI :
The Korean Magnetics Society
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Volume & Issues
Volume 2, Issue 3 - Nov 1992
Volume 2, Issue 2 - Jun 1992
Volume 2, Issue 1 - Feb 1992
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Effect of Two-step Annealing on the Magnetic Properties of
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 91~98
amorphous alloy ribbon the effect to two-step annealing on the soft magnetic properties has been studied. By two-step annealing method which the second annealing at low temperature of
for 2 hours is undertaken after the primary annealing at high temperature above
for 20 minutes at the vacuum state, the coercive force and the squareness are not changed nearly but the initial permeability at d.c. and the effective permeability at a.c. are remark-ably increased compared with the one-step annealing. The maxima of the initial permeability and the effective permeability at 1 kHz after the two-step annealing are 290,000 and 41,000, respectively, which are 30% higher than those of the one-step annealing. The change of magnetic properties with annealing temperature is discussed in terms of the residual stress, the domain size, the cluster and the crystalline phase.
Doping Effects with
in Mn-Zn Ferrites
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 99~104
The permeability vs. temperature curve, the loss factor and the microstructure of a commercial Mn-Zn ferrites were investigated by X-ray diffractometer, SEM and LCR meter, where the additives, such as
, were added to the main composition. Their wt% were 0.05, 0.3 and 1.0, respectively. When the content of additives increased, the SPM (Secondary Peak Maximum) of the permeability moved from
to below the room temperature. This movement, without the significant change of the microstructure, is because Sn and Ge, having the different ionic radius, were soluble in the matrix. There was no variation of the permeability with the frequency up to 100 kHz. And the loss factor showed the maximum value at 10 kHz.
Ferrimagnetic Resonance Studies of Poly-crystalline
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 105~113
Magnetic Properties of
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 114~118
Effects of Sputtering Ar Pressure on Magnetic and Magneto-optical Propwrties in Compositionally Modulated Co/Pd Supwrlattice Thin Films
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 119~124
We have investigated the effects of sputtering Ar gas pressure on magnetic and magneto-optical properties in compositionally modulated Co/Pd superlattice thin films. The samples were prepared by dc magnetron sputtering from 2-in.-diam Co and Pd targets by alternately exposing the substrates to targets. Sputtering Ar gas pressure was varied from 2 to 30 mTorr. All samples had same bilayer thicknesses composed of 2-
-thick Co and 9-
-thick Pd sublayers. It was observed that the colum-nar structure was more distinctively developed with increasing Ar gas pressure. We observed that the intrinsic uniaxial anisotropy energy, magnetization and polar Kerr rotation were decreased with increasing Ar gas pressures. Large coercivity and perfect squareness were attained by the deposition at the high Ar gas pressure. We believe that the results are mainly ascribed the variation of micro-structure with sputtering Ar gas pressure.
Magnetic and Magneto-Optic Properties of Tb/Fe Multilayers
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 125~131
Design of Cylindrical Magnetic Gradient field for NMR-CT
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 132~139
We have designed a magnetic field gradient useful for cylindrical imaging in NMR-CT. The direc¬tion of the designed field is parallel to the axis and the gradient in the radial direction of cylindrical coordinate is monotonically increasing. The ratio of the gradient in the radial and axial direction is greater than 10 near the center of coordinate. This ratio depends on solenoid length, the number of reverse current turns at center, and the amount of the reverse current. We built a gradient coil based on the numerical simulation and tested the field generated by NMR-CT. The resulting image matches with the theoretical expectation within 10% error. Since the data acquisition time of 1-D imaging is significantly shorter than 2-D imaging, it becomes possible to image much more dynamic objects by the use of this gradient field.
Preisach Model for Analyzing the Permanent Magnet System with Hysteresis Characteristics
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 140~144
Magnetization of permanent magnet in the strong magnetic field is changeable. So the change of magnetization must be considered for the accurate analysis of the system with permanent magnets. But the hysteresis characteristice of permanent magnet cannot be represented in simple mathematical form. In this paper, Preisach model combined with finite element method which can describe the hysteresis phenomena is applied to analyze the permanent magnet system. To validate the method, it is applied to the force calculations between two magnets with different coercivities and the numerical results are compared with measured data.
Effects of Magnetizing Currents on Remanent Flux Density in Multipole Magnetizer
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 145~149
The characteristics of electromagnetic devices with permanent magnet depends greatly on the remanence pattern of permanent magnet. So, it is necessary to analyze the pattern of remanence in permanent magnet. This paper presents a finite element analysis of magnetizer considering the nonlinearity and anisotropy of yoke and magnet in magnetizer. The distributions of magnetizations are obtained according to the variations of magnetizing currents for two kinds of magnetizers with different magnetizing poles. It is found that the excessive magnetizing current results in the reduction and polarity reversion of magnetization in the multi-pole magnetizing system where the pole angle is too small. During the design and analyzing of multi-pole magnetizer, it must be considered that there exists an optimal value of magnetizing current and pole angle of magnetizer.
Construction of a Low Magnetic Field Standard System Using a Precision Solenoid
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 150~155
The low magnetic field standard below 1 mT with resolution of 100 nT has been established for the calibration and testing of low field magnetometers. A precision single layered solenoid, which is made of quartz tube and bare copper wire, was constructed in order to generate a precise magnetic field. To improve the field homogeneity in the solenoid, three-current method was employed. The injected current and injection points on the solenoid were optimized by computer simulation. The magnetic field uncertainty in the solenoid was 0.1 % and 0.01 % in the range of
from the center for a single and three-current methods respectively. We also constructed a testing system for the dynamic properties of low field magnetometers.
Construction of an Earth's Field Compensation System for the Mcasurement of. Proton Gyromagnetic Ratio
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 156~162
In the measurement of proton gyromagnetic ratio by a low field cechnique, the compensation of earth's field is required to keep a zero-field space. The constant earth's fild is compensated by a cur-rent flowing through a Helmholtz coil, whereas small time-varying component is compensated automatically by a closed loop of feedback system. A feedback amplifier, and two three-dimensional Helmholtz coils having the same coil constant have been constructed in order to compensate the earth's field. field. Preliminary test performed at the ordinary laboratory showed that the time-vary-ing field of
and the constant field have been reduced to the level of
using the compensating system.
Magnetic Measurement of PLS Storage Ring Prototype Dipole Magnet
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 163~168
Results of magnetic measurement of a prototype Storage Ring dipole magnet for the Pohang Light Source (PLS) are summarized. Hall probe mapping and rotating coil methods are used to measure field profiles and integrated field properties. End chamfering experiments are performed on the as-built magnet, which has four removable pole-end pieces, to meet the specifications set from beam dy-namics requirement. The corrected magnet has efficiency of 99.7% at 2.0 GeV excitation ad higher order multipole error levels less than the specifications for all excitations, showing that the magnet has appropriate properties for the PLS Storage Ring.
광자기 기록매체의 연구개발 동향
Journal of the Korean Magnetics Society, volume 2, issue 2, 1992, Pages 169~177