• Journal of Magnetics
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• v.16 no.4
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• pp.453-456
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• 2011

Demagnetization for a tube sample which was made of a galvanized steel sheet was performed by applying a magnetic field with a decrement to remove the remanent magnetization of the material. An orthogonal fluxgate magnetic field sensor was used to measure a magnetic field created from a ferromagnetic material. To evaluate the remanent magnetization, the measured magnetic fields were separated into two magnetic field components by the remnant magnetization and the induced one. The horizontal and the vertical bias fields should be controlled separately during demagnetization to remove the horizontal and the vertical components of the remanent magnetization of the tube sample.

• Journal of Magnetics
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• v.2 no.4
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• pp.135-137
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• 1997

We report the salient features of the magnetic properties of amorphous TM70Cr5Si10B15(TM=Fe, Co, Ni) alloys. The temperature dependence of magnetization for amorphous ribbons were measured by a SQUID and a VSM from 5 K to 700 K under an external field of 10 kOe. Except TM70Cr5Si10B15 that shows a paramagnetic behaviour, both Fe and Co based amorphous alloys show a typical ferromagnetic thermo-magnetization curves. For these two ferromagnetic alloys, the saturation magnetization in the temperature range from 5 K to about 0.4 Tc can be descrived by the Bloch relation, Ms (T)=Ms(0) [1-BT3/2-CT5/2]. The spin wave stiffness constants and the range of exchange interaction were analyzed from the magnetization behaviour. The variation of the magnetic properties are discussed and compared with the composition of the alloys.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.49 no.10
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• pp.652-658
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• 2000

In many cases, ferrite magnets of ferrite bonded magnets used in inner-rotor type small brushless DC(BLDC) motors do not have rotor core. The magnetization directions of permanent magnets do not have only parallel or radial direction. In this case, the characteristics of magnets are different from cored type ones which have uniform magnetization direction. In this paper, the magnetization directions and intensities of a ferrite magnet and a ferrite bonded magnet are analyzed by finite element analysis for magnetization procedure. The characteristics of inner-rotor type BLDC motor are analyzed by using the analyzed results. The validity of the method is verified by comparing the analyzed results with measured ones.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.7
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• pp.437-443
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• 2004

In this work the AC loss measurement setup based on an iron core background magnet, not used in a conventional one, has been successfully developed. To prove its validity, a round-robin test for the same Bi-2223 tape sample among three institutes has been done. The results show that the self-field and magnetization losses from the developed setup well agree with the losses measured at two other institutes of Korea Basic Science Institute and Yokohama National University. The measured magnetization losses for parallel or perpendicular fields can be well predicted from the slab model or the strip model for a filamentary region. However the magnetization losses for longitudinal fields can be rather predicted by the slab model for a decoupled filament. The self-field losses are well explained by the Norris ellipse model.

• Progress in Superconductivity and Cryogenics
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• v.7 no.3
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• pp.13-16
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• 2005

Multi-stacked HTS tapes are needed to conduct large current in the power application. In this paper magnetization losses of the multi-stacked YBCO coated conductor and the BSCCO tape have been measured and compared. Magnetization losses of single tape, 2-stacked, 3-stacked and 4-stacked HTS tapes have been presented in this paper. Multi-stacked tapes have been fabricated using face-to-face type stacking method. Measurements of magnetization loss were performed under various stacked of external magnetic field to consider the anisotropic characteristics of HTS tapes. Test results show that loss density per unit volume decreased for both YBCO coated conductors and BSCCO tapes when the stacking number of tapes is increased. As the external magnetic field decreased, the ratio of decrement has risen because the full penetration magnetic field(Bp) of the multi-stacked tape is larger than that of the single tape.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.8
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• pp.1412-1417
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• 2007

Magnetic anomaly generated around a ship is mainly due to the permanent magnetization(PM) and induced magnetization (IM) remaining on the hull. It is very difficult to predict the direction and its magnitude of the permanent magnetization distributed over the hull, that is caused by mechanical or thermal stress. In this paper, an effective method is proposed to separate two components, the one produced by PM and the other by IM, from the underwater earth field signal distorted by the ferromagnetic material of the ship. The method can easily provide the two kinds of magnetic anomaly through exploiting experimental results and 3D electromagnetic field analyses even though the PM distribution on the hull is not known. To validate the proposed method, a model ship is manufactured and tested. The results would be of much help to basis research for securing safe navigation of a ship against dangerous factors in underwater.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1222-1224
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• 2005

AC loss is an important factor in the development of superconducting tapes and superconducting power applications. In this paper, magnetization loss in YBCO coated conductor have been measured and compared with Brandt equation. Measurements of magnetization loss were performed under various angles of external magnetic field to consider the anisotropic characteristics of YBCO coated conductors. The results show that measured values of magnetization loss agreed well with the calculated value by using Brandt equation, especially at large degrees of incidence angle. The magnetization losses were strongly influenced by the direction of external magnet field as were expected.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.11
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• pp.995-999
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• 2007

We investigated the characteristics of a flux-lock type superconducting fault current limiter(SFCL) considering magnetization characteristic of iron core. The flux-lock type SFCL, like other types of SFCLs using the iron core, undergoes the saturation of the iron core during the initial fault time. Therefore, if the design to prevent the saturation of the iron core is considered, the effective fault current limiting operation can be achieved. Through the analysis for its equivalent circuit including the magnetization characteristic of the iron core, the limiting impedance of the flux-lock type SFCL was drawn. The magnetization currents and the limited currents of SFCL, which were dependent on the winding direction and the turns' ratio between two coils, were investigated from the short circuit experiment. It was confirmed that their experimental results agreed with the analysis ones.

• Journal of Magnetics
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• v.12 no.1
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• pp.17-20
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• 2007

We performed magnetic force microscopy (MFM) observation on array of Co dots in order to understand magnetic state and magnetization behavior of submicron sized Co dots patterned on GaMnAs bridge. MFM observations showed the magnetization reversal and processes of local magnetization of individual ferromagnetic Co nanodots. Magnetic state of Co dots either single domain or vortex is dependent on geometrical size and thickness. Transition from single domain to vortex state can be realized with MFM tip assisted local field. Magnetization reversal process takes place through sequential reversal of individual dots. Localized inhomogeneous magnetic field can be manipulated by controlling magnetic state of individual Co dot in the array structure.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.46-49
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• 2022

Since CORC^®(Conductor on Round Core) is made of multiple strands of a superconducting tape to conduct a large current, it is difficult to measure the critical current due to the limitation of a capacity of a power supply. The magnetization loss of a superconductor is dependent on the full penetration field. The full penetration field corresponds to the inflection point of the magnetization loss graph with respect to the external magnetic field. We propose a method to predict the critical current of CORC^® indirectly. This method uses the measured magnetization losses of various CORC^® samples for the prediction of the critical currents.