• Proceedings of the Korean Magnestics Society Conference
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• 1996.10a
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• pp.96-97
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• 1996

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1421-1423
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• 2003

The relationship between magnetic properties of BiPbSrCaCuo superconductor and externally applied magnetic field was studied to develop a magnetic field polarity sensor. The behavior was related to the magnetic flux trapped in the superconductor, which penetrates through the material by the external magnetic field. Some portion of the superconductor was changed to a normal state by the trapped magnetic flux. Electrical characteristics of the superconductor with trapped magnetic flux were extremely sensitive to the external magnetic field and showed different responses depending on the direction of the magnetic field.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.7
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• pp.788-792
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• 2004

The Electromagnetic properties in BiPbSrCaCuO superconductor was studied. In the measurement of current-voltage characteristics, a voltage across the superconducting sample was observed on applying an external magnetic field. The voltage continues to appear the removal of the magnetic field. The appearance of the voltage is ascribed to the trapping of magnetic flux. Depanding on the direction of appied magnetic flux less than $2.5\times{10}^-5$ T, the voltage in the magnetized sample increases or decreases. It is considered that mechanism of voltage occurrence can be explained by applying filament model.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1549-1551
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• 2004

The Electromagnetic properties in BiPbSrCaCuO superconductor was studied. In the measurement of current-voltage characteristics, a voltage across the superconducting sample was observed on applying an external magnetic field. The voltage continues to appear the removal of the magnetic field. The appearance of the voltage is ascribed to the trapping of magnetic flux. Depanding on the direction of applied magnetic flux less than 2.5${\times}$10-5 T, the voltage in the magnetized sample increases or decreases. It is considered that mechanism of voltage occurrence can be explained by applying filament model.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.10
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• pp.453-456
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• 2005

We have fabricated superconducting ceramics by chemical process. A high Tc superconducting with a nominal composition of YBaCuO was prepared by the pyrolysis method. The electromagnetic properties in YBaCuO superconductor was studied. In the measurement of current-voltage characteristics, a voltage across the superconducting sample was observed on applying an external magnetic field. The voltage increases with increase in applied magnetic flux, but it becomes constant at about 10$^{-2}$T. The voltage continues to appear the removal of the magnetic field. The appearance of the voltage is ascribed to the trapping of magnetic flux. Depending on the direction of applied magnetic flux less than 2.5$\times$10$^{-5}$ T, the voltage in the magnetized sample increases or decreases.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.55 no.10
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• pp.481-484
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• 2006

The electric properties in YBCO superconductor was studied. In the measurement of current-voltage characteristics, a voltage across the superconducting sample was observed on applying an external magnetic field. The voltage increases with increase in applied magnetic flux, but it becomes constant at about $10^{-2}T$. The voltage continues to appear the removal of the magnetic field. The appearance of the voltage is ascribed to the trapping of magnetic flux. Depending on the direction of applied magnetic flux less than $2.5{\times}10^{-5}T$, the voltage in the magnetized sample increases or decreases.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.12
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• pp.1032-1038
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• 2000

Ni$_{81}$$Fe_{19}$(200 nm) thin films have been deposited by RF-magnetron sputtering on Si(001) substrates, Atomic force microscopy(AFM), X-ray diffraction(XRD) and magnetoresistance(MR) measurements of the thin films for investigating electromagnetic properties and microstructures were employed. During field annelaing for 1hr, there was no big difference n XRD patterns of Ni$_{81}$$Fe_{19}$ thin films. However, there was a significant change in XRD patterns of Ni$_{81}$$Fe_{19}$ thin films deposited at 40$0^{\circ}C$ during in-situ magnetic field deposition. The degree of surface roughness increased with increasing annealing and deposition temperature. With variation of surface roughness, there was no significant difference in MR Characteristics of Ni$_{18}$ $Fe_{19}$ thin films in 1hr-annealed case. High MR ratio was observed in the case of in-situ field deposited Ni$_{81}$$Fe_{19}$ films. 19/ films.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5A
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• pp.737-746
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• 2008

Recently, NDTs (Non-Destructive Techniques) using electromagnetic(EM) properties are applied to the performance evaluation for RC (Reinforced Concrete) structures. Since nonmetallic materials which are cement-based system have their unique dielectric constant and conductivity, they can be characterized and changed with different mixture conditions like W/C (water to cement) ratios and unit cement weight. In a room condition, cement mortar is generally dry so that porosity plays a major role in EM properties, which is determined at early-aged stage and also be affected by curing condition. In this paper, EM properties (dielectric constant and conductivity) in cement mortar specimens with 4 different W/C ratios are measured in the wide region of 0.2 GHz~20 GHz. Each specimen has different submerged curing period from 0 to 28 days and then EM measurement is performed after 4 weeks. Furthermore, porosity at the age of 28 days is measured through MIP (Mercury Intrusion Porosimeter) and saturation is also measured through amount of water loss in room condition. In order to evaluate the porosity from the initial curing stage, numerical analysis based on the modeling for the behavior in early-aged concrete is performed and the calculated results of porosity and measured EM properties are analyzed. For the convenient comparison with influencing parameters like W/C ratios and curing period, EM properties from 5 GHz to 15 GHz are averaged as one value. For 4 weeks, the averaged dielectric constant and conductivity in cement mortar are linearly decrease with higher W/C ratios and they increase in proportion to the square root of curing period regardless of W/C ratios.

• Korean Journal of Crystallography
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• v.12 no.3
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• pp.182-187
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• 2001

The purpose of this study is to investigate the degradation of soft magnetic properties of Fe-Hf-N thin films after annealing in vacuum. They were annealed at 450℃∼650℃. The microstructure and crystal phase of the selected area of the thin films were analyzed by TEM and SAD. After annealing at 450℃-600℃, the coercivity of the films increased by 0.2 Oe and the effective permeability decreased by 1500 as compared with them before annealing due to the growth of α-Fe crystallites. The saturation magnetic flux density of the films increased by 0.5 KG after annealing under 600℃. However, the soft magnetic properties of the film annealed at 650℃ degraded abruptly, which was attributed to the destruction of nano-crystalline microstructure of the film due to the rapid growth of α-Fe crystallites with the segregation of N sited in the α-Fe lattice into HfN.