• Journal of the Korean Magnetics Society
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• v.8 no.4
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• pp.224-230
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• 1998

The relationships between R-H curves of gaint magnetoresistance (GMR) spin valve trilayer films and M-H curves of each magnetic layer consisting of the trilayer films were analyzed and simple formula representing the relations between the curves were suggested for theoretical analysis and study of magnetoresistance (MR) in those films, especially where the MR is from the difference of coercivity. Using two kinds of NiFe/Cu/Co films, which had been deposited on Cu(50 $\AA$)/Si(111, 4$^{\circ}$ tilt-cut) and Cu(50 $\AA$)/glass, R-H and M-H curves were measured and compared with the calculated ones, which were obtained by appying the M-H curves of single NiFe and Co films, deposited on the same substrates, to the previously reported single-domain and multi-domain models. The calcuated ones were well consistent with the measured ones and the suggested simple relationships between R-H and M-H curves are thought to be very useful for the deep understanding of MR behavior and the reasonable approach to improve MR properties in GMR spin valve trilayer films.

• Journal of the Korean Magnetics Society
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• v.3 no.2
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• pp.121-124
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• 1993

보자력이 큰 강자성체의 자기이력곡선, 자기변형, 자기이방성등의 측정에 사용할수 있는 펄스전자석을 설계제작하였다. 철심의 형상이 주어졌을때 권선의 회수에 따른 전자석의 여러특성과 축전기 방전시의 전류진폭 감쇄비등을 계산하는 일반식을 유도하고 그것에 의하여 철심단면적 46 nm * 32 nm, 공기간격 28nm의 전자석을 설계 제작하여 20 mT/A의 기울기로 0.49 T까지 직선적인 자기장 대 전류특성을 얻었다. 이 전자석에 에너로그 적분기에 의한 자속계를 부쳐서 박막 또는 박대시료의 major 및 minor 이력곡선을 단번에 쉽게 얻을 수 있는 자기이력곡선 측정기가 구성되었다.

• Journal of the Korean Magnetics Society
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• v.6 no.1
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• pp.1-6
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• 1996

To simulate the characteristics of magnetic exchange coupling at the interface of MR/TbCo thin films, the directions of magnetizations were calculated by minimizing energy in the films. Newton method and Gauss-Seidel method were used. The width of M-H curve increased with TbCo anisotropy constant, and with the thickness of the transition region of TbCo layer. Hysteresis loop width became extremely narrow (less than 10 Oe of coercivity), when the TbCo transition region length was $400\;\AA$. Also the hysteresis loop of films with low interfacial exchange coupling constant was similiar to that of short transition region length. When interfacial exchange coupling constant was 1/100 of perfect coupling, hysteresis loop showed a coercivity of less than 10 Oe. Comparing the measured hysteresis loop of a fabricated sample with that of simulated one, exchange coupling con¬stant could be estimated.

• Journal of the Korean Magnetics Society
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• v.5 no.4
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• pp.251-260
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• 1995

It has been reported that Co-based amorphous ferromagnetic alloys annealed in a small magnetic field develop a reproducible, asymmetric hysteresis loop. If the direction of the field during annealing is regarded as +, the magnetization reversal from - to + is smooth and reversible, with its slope determined by the demagnetizing field of the sample. This phenomenon is called the asymmetric magnetization reversal (AMR). The shape of the hyster-esis loop depends sensitively on the condition during the anneal and the alloy composition. Here, we report on the effect of the annealing temperature and time on AMR in a zero magnetostrictive ferromagnetic amorphous alloy. The AMR effect develops in a very short time at a reasonably high temperature, but is stabilized by annealing for a prolonged time.

• Journal of the Korean Magnetics Society
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• v.25 no.4
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• pp.123-128
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• 2015

The iron is an element having a high yield strength, mechanical hardness, good electrical conductivity, and also it has been used in various fields because of ease machining. In bridges have been used tendon made of a steel wire for large loads and light weight. Tension measurement of tendon employed in PreStressed Concrete (PSC) bridge is very important for the bridge safety check. NDT (Non-Destructive Testing) is essential for the safety check, however, magnetic NDT is difficult to apply due to the non-linear magnetization curve and hysteresis loop in the magnetic properties. In this work, for basic study of magnetic NDT application, we have constructed a B-H loop measuring system for 7-strand tendon of which diameter is 15.5 mm, and which can apply tensile stress up to 2.0 GPa. We have measured hysteresis loops of two kinds of tendons under different tensile stress. Amplitude permeability and maximum magnetic induction near knee show the most sensitive and high linearity depends on tensile stress. Relative amplitude permeability was decreased from 500 to 200 and maximum magnetic flux density changed 0.6 T.

• Journal of the Korean Magnetics Society
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• v.14 no.3
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• pp.105-108
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• 2004

Array of magnetic Ni nanostructures has been fabricated on Si substrate by using nanoporous alumina film as a mask during deposition. The nanostructures are truncated cone-shape and the lateral sizes are comparable to height. While the continuous film shows well-defined in-plane magnetization, the nanostructure shows perpendicular component of magnetization at remanence. The hysterectic behavior of nanostructures is dominated by the demagnetizing field instead of interaction among them.

• Proceedings of the Korean Magnestics Society Conference
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• 2000.05a
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• pp.68-69
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• 2000

• Proceedings of the Korean Magnestics Society Conference
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• 1991.11a
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• pp.44-45
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• 1991

• Proceedings of the Korean Magnestics Society Conference
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• 1993.03a
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• pp.30-31
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• 1993

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.900-904
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• 1995

We have developed a new torque magnetometric method for measuring the M-H hysteresis loop of a spheroid-shape magnetic material having a uniaxial anisotropy. Our torque magnetometric method gives the saturation magnetization as well as the remnant magnetization, simultaneously. A torque magnetometer having the torque sensitivity of $10^{-6}$ dyn cm could give the extreamly high sensitivity of $10^{-9}$ emu in measuring the magnetic moment, which is high enough to measure the magnetic moment of a monolayer Ni film. The accuracy of the present method was negligibly affected even at the applied fields near the coercivity where magnetization was inhomogeneous.