• Journal of Magnetics
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• v.1 no.2
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• pp.60-63
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• 1996

The first and second harmonics have been measured in the iron whisker with the axial current that produces a circular field. The observed harmonics profiles have been discussed in terms of theoretical analysis based on the nonlinear, asymmetric magnetization that are related to the nucleation, transformation and annihilation of domains. The change of second harmonics profile is more sensitive to the domain variation than that of first harmonics.

• Journal of Acupuncture Research
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• v.31 no.2
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• pp.21-30
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• 2014

Objectives : Manufacturing and manipulation techniques of acupuncture can be interpreted as an induced electromagnetic viewpoint, as proposed in previous study. Considering from this point of view, the magnetization of needles should be essential to enhance the electromagnetic effects during the behavior of the acupuncture needling. Methods : The current disposable needles are made of non-magnetic stainless steels, so ferromagnetic materials were searched as suitable substitutes. Meanwhile, at the practical view, stainless steels are very available for the several superior properties like as corrosion resistance, strength, etc., magnetic stainless steels were first investigated. Some types of them still preserved the ferromagnetic properties of iron, so trial needles were made with them. And then magnetization of them were followed. Results : Among the hundreds types of stainless steels, martensitic or ferritic ones are ferromagnetic. The needles made with these ferromagnetic wires were magnetized, and polarized by magnetizer, and their magnetic properties were improved. Moreover, in addition to the superiority of the magnetism, the electrical and thermal conductivities of them were even better than those of the current austenitic stainless steels. Conclusions : Through the developmental study based on the electromagnetic viewpoint, the magnetized and polarized acupuncture needles were completed. This means that these needles having improved magnetism can be used to improve the electromagnetic needling effects, and moreover, their superiorities in the electrical and thermal conductivities can also give another benefits in treatments of electrical or warm needling.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.9
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• pp.1392-1399
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• 1997

In order to determine the Mode I stress intensity factor ($K_1$) experimentally by means of the alternating current potential drop(ACPD) technique, the change in potential drop due to load for a ferromagnetic material containing a two-dimensional surface crack was examined. The cause of the change in potential drop and the effect of the magnetic flux on the change in potential drop were clarified by using the measuring systems with and without removing the magnetic flux from the circumference of the specimen. To remove the magnetic flux, a new measuring system was made by utilizing the characteristic of coaxial transmission line. The change in potential drop in the case without magnetic flux in the air was caused by the change in electromagnetic properties near the crack tip due to magnetization. The relationship between the change in potential drop and the change in $K_I$ was linealized by demagnetization and was found to be independent of the crack length.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.48-57
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• 2008

MR Fluid, one of functional fluids, is developed for the application to automobile products. MR CDC damper using MR fluid has following principles. When ar electric current is applied to the solenoid, apparent viscosity of MR fluid passing through the annular gap which acts as magnetic circuits varies directly as the intensity of the current. These devices have a simple structure and excellent lime response characteristics, emerging as the alternatives of the conventional semi-active suspension systems. In this study, a design procedure of the magnetic circuit through the solenoid fore and the flux ring functioning as a magnetic path is investigated so as to optimize the design and performance of MR CDC dampers for the vehicles. In addition, an operating point on the B-H curve, the magnetization according to the variation in the annular gap, the pole piece width and the density of MR fluid are studied to design the optimal piston head within the restrained dimension range.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.11
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• pp.934-940
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• 2001

Magnetic properties were investigated for Si/SiO$_2$/NiFe(300 )/A1$_2$O$_3$(t)/Co(200 ) junction related with the parameters of $Al_2$O$_3$. Insulating $Al_2$O$_3$ layer was formed by depositing a 5~40 thick Al layer, followed by a 90~120s RF plasma oxidation in an $O_2$ atmosphere. Magnetoresistance was not observed for tunnel junction with 5~10 thick Al layer, but magnetoresistance was observed large for tunnel junction with 15~40 thick Al layer. Oxidation time did not largely influence magnetoresistance. Tunnel magnetoresistance effect depended on magnetization behavior of two ferromagnetic layers. Tunneling junction was confirmed through nonlinear I-V curve. In this work, tunneling magnetoresistance(TMR) up to 30 % was observed. This apparent TMR is an artifact of the nonuniform current flow over the junction in the cross geometry of the electrodes.

• Journal of the Korean Magnetics Society
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• v.19 no.1
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• pp.22-27
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• 2009

Reduction of the critical current density ($J_c$) for STT magnetization switching is most important issue of magnetic tunnel junctions (MTJs) based MRAM. This report describes how to decrease the Jc and will introduce the recent research progresses of STT-MRAM devices with material engineering and structural improvement, respectively.

• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.31-34
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• 2009

An HTS power cable is generally composed of 2 layers for conducting and 1 layer for shielding. For the analysis of AC loss of an HTS power cable, 2-dimensional magnetic field analysis is carried out. The magnetization loss in HTS cable core was calculated, and the transport current loss was obtained from the monoblock equation and the elliptical Norris Equation. And the total AC loss of the cable was expected by the sum of magnetization loss and transport current loss. The variation of ac loss with respect to the gap and uncertain factor between the superconducting tapes was investigated, and the ac loss of 22.9kV/50MVA high-Tc superconducting power cable was calculated. These results well agree with those of experiment.

• Proceedings of the KIEE Conference
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• 1990.11a
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• pp.28-31
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• 1990

In perpendicular magnetic recording system, the magnetic recording and reproduction characteristics of isolated transition of magnetization is simulated in this paper. The recording system which is magneto-static system is analyzed using two-dimensional finite element method and the characteristics of hysteresis of recording media is considered. The results show that the optimizing current is exist in magnetic recording system.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.2
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• pp.90-93
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• 2018

This aim of this study was to develop a process for creating bulk single-crystal YBaCuO superconductors in a high magnetic field. To support the bulk unidirectional growth of $YBa_2Cu_3O_{7-y}$, $SmBa_2Cu_3O_{7-y}$ seeds were planted inside YBaCuO composites and samples were produced by melting, enabling the growth of two YBaCuO superconductors. Due to the magnetism generated inside the superconductor of the upper sample, the magnetization inside the superconducting single crystals was evenly distributed, the sharpness of the induced magnetic force was improved, and the superconducting magnetization were significantly improved. This approach is widely applicable for the production of superconducting wires and current leads used for DC power breakers.

• 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).