• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.9
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• pp.500-506
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• 2004

This paper proposes a modified current differential relay for transformer protection unaffected by the remanent flux. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. To cope with the remanent flux, before saturation, the relay calculates the core-loss current and uses it to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the actual core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. This paper concludes by implementing the relay on a hardware platform based on a digital signal processor. The relay discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.55 no.3
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• pp.95-101
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• 2006

This paper proposes a modified current differential relay for $Y-{\Delta}$ transformer protection. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. A method to estimate the circulating component of the delta winding current is proposed. To cope with the remanent flux, before saturation, the core-loss current is calculated and used to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Test results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation, because the exciting current was successfully compensated. This paper concludes by implementing the relay on a hardware platform based on a digital signal processor. The relay does not require additional restraining signal and thus cause time delay of the relay.

• Proceedings of the KIEE Conference
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• 2004.11b
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• pp.9-13
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• 2004

This paper proposes a modified current differential relay for Y-$\Delta$ transformer protection. The relay uses the same restraining current as a conventional relay, but the differential current is modified to compensate for the effects of the exciting current. A method to estimate the circulating component of the delta winding current is proposed. To cope with the remanent flux, before saturation, the core-loss current is calculated and used to modify the measured differential current. When the core then enters saturation, the initial value of the flux is obtained by inserting the modified differential current at the start of saturation into the magnetization cure. Thereafter, the core flux is then derived and used in conjunction with the magnetization curve to calculate the magnetizing current. A modified differential current is then derived that compensates for the core-loss and magnetizing currents. The performance of the proposed differential relay was compared against a conventional differential relay. Test results indicate that the modified relay remained stable during severe magnetic inrush and over-excitation because the exciting current was successfully compensated. The relay correctly discriminates magnetic inrush and over-excitation from an internal fault and is not affected by the level of remanent flux.

• 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.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.91-95
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• 2002

This paper describes the design of planar circulators with propellers resonator including a plurality of symmetric magnetic walls. One purpose of the paper is to present insertion loss on this resonator for magnetic loss, dielectric loss, magnetic field and saturation magnetization. Another is to study the effect of propeller resonator on response characteristics. The paper includes the description of one commercial circulator that is compatible with the data obtained

• 한국지구물리탐사학회:학술대회논문집
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• 2007.12a
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• pp.27-30
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• 2007

Martian meteorites are the only available Martian Materials on Earth. A suite of demagnetization experiments, temperature dependence of saturation magnetization, scanning electron microscopy, and electron microprobe analysis were carried out to characterize the remanent magnetization carriers of Martian meteorite SaU 008. A stable paleomagnetic record of SaU 008 originates from a newly found spinel ((Fe, Cr, Ti)-spinel) whose composition has never been documented (or identified as magnetic).

• 한국초전도학회:학술대회논문집
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• v.15
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• pp.33-33
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• 2005

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.343-350
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• 1995

An overview will be given on recent Mossbauer and magnetization investigation of the applied field dependence of the magnetic properties of typical systems without strong magnetic anisotropy and showing the absence of magnetic saturation in high fields (including iron-rich spin glass (amorphous $Fe_{93}Zr_{7}$, soft ferromagnets (amorphous $Fe_{88}Zr_{12}$, $Fe_{70}Ni_{20}Zr_{10}$ and $Fe_{88}B_{12}$) and pure Fe). The results emphasize that shape anisotropy due to surface irregularities causes misalignment between the magnetization and the applied field in the otherwise collinear magnetic structure.

• Journal of Magnetics
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• v.15 no.4
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• pp.199-203
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• 2010

This paper discusses the effectiveness of high magnetization saturation in ILI (In-Line Inspection) using an MFL (Magnetic Flux Leakage) tool, and introduces a practical method for improving the magnetization level together with the piggability. Thin steel plates, replacing the conventional wire brushes were used as conductors to transfer the magnetic flux to the pipe wall. The newly designed MFL tool was compared with the conventional version by means of FEM (Finite Element Method) analysis and full-scale experiments. In the results, the newly developed magnetization system obtained a stronger MFL signal amplitude, specially 2.7 times stronger, than that obtained by the conventional magnetization system for the same defect dimensions.

• Journal of the Korean Magnetics Society
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• v.4 no.2
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• pp.135-141
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• 1994

With the variation of Cr content and $N_2$ flow ratio, the soft magnetic properties, corrosion resistance and reactivity of the sputtered nanocrystalline FeZrCrN thin flims were investigated. In case of FeZrCrN thin films, a saturation magnetization was decreased with increasing $N_2$ flow ratio. In addition, good soft magnetic properties were obtained at the flow ratio of 3% $N_2$. The $Fe_{64.9}Zr_{8.8}Cr_{5.8}N_{20.5}$ nanocrystalline thin film after annealing at $550^{\circ}C$ exhibited the saturation magnetization of 12.5kG, low coercivity of 0.4 Oe and high permeability of 2600 at 5 MHz. Films containing up to 7.5% Cr showed an enhanced corrosion resistance and reduced reactivity with the bonding glass without degradation of soft magnetic properties, although the saturation magnetization was decreased slightly with the Cr addtion.