• 한국재료학회지
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• 제19권6호
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• pp.319-324
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• 2009

The deposition behavior and structural and magnetic properties of electroless Co-B and Co-Fe-B deposits, as well as the amorphous ribbon substrates, were investigated. These Co-based alloy deposits exhibited characteristic polycrystalline structures and surface morphology and magnetic properties that were dependent on the type of amorphous substrates. The catalytic activity sequence of the amorphous ribbon electrodes for anodic oxidation of DMAB was estimated from the current density-potential curve in the anodic partial electrolytic bath that did not contain the metal ions. Both the deposition rate and potential in the initial region were obtained in order of the catalytic activity, depending on the alloy compositions of the substrates. The deposition rate linearly varied against the deposition time. The initial deposition potential may have also determined the structural and magnetic properties of the deposit based on the thickness of ${\mu}m$ order. Furthermore, a basic study of the electroless deposition processes on an amorphous ribbon substrate has been carried out in connection with the structural and magnetic properties of the deposits.

• Journal of Magnetics
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• 제15권4호
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• pp.194-198
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• 2010

In our present work, we developed a GMI (giant magnetoimpedance) sensor system to detect magnetic fields in the milli gauss range based on the asymmetric magnetoimpedance (AGMI) effect in Co-based amorphous ribbon with self bias field produced by field-annealing in open air. The system comprises magnetoimpedance sensor probe, signal conditioning circuits, A/D converter, USB controller, notebook computer, and program for measurement and display. Sensor probe was constructed by wire-bonding the cobalt based amorphous ribbon with dimensions $10\;mm\;{\times}\;1\;mm\;{\times}\;20\;{\mu}m$ on a printed circuit board. Negative feedback was used to remove the hysteresis and temperature dependence and to increase the linearity of the system. Sensitivity of the milli gauss meter was 0.3 V/Oe and the magnetic field resolution and environmental noise level were less than 0.01 Oe and 2 mOe, respectively, in an unshielded room.

• Journal of Magnetics
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• 제12권1호
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• pp.31-34
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• 2007

The Co-based ribbons with different length were annealed in different magnetic field and GMI profiles were investigated in order to clarify the influence of ribbon size on GMI effect. The GMI ratio decreased with the decreasing in length and also decreased with increasing annealing field. While, the slope of GMI profiles inclined and the field range showing linearity was broadened. It shows prospect to low field sensor, especially for a navigation sensor.

• 한국수소및신에너지학회논문집
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• 제18권2호
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• pp.182-188
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• 2007

[ $Zr_{50}-Ni_{27}-Nb_{18}-Co_5$ ] amorphous alloys ribbon was prepared by a single-roller melt-spinning technique. In order to improve the hydrogen kinetics Pd-coating were carried out on each side of the amorphous ribbon. Pd prevents oxidation of Zr and catalyses the dissociation of molecular hydrogen to atomic hydrogen. In this work, the hydrogen embrittlement and surface properties on Zr-based amorphous alloys were investigated. The Zr-based amorphous alloys were characterized by X-ray diffractometry(XRD) and differential scanning calorimetry(DSC). The morphology of surface and roughness was observed by using scanning electron microscopy(SEM) and atomic force microscopy (AFM). A lattice parameter of both Pd and Zr-based amorphous alloy was increased after hydrogen permeation at 473 K. After hydrogen permeation at 473 K, some cracks were observed on the surface of Pd, which was the cause for the hydrogen embrittlement. The crystallization temperature of Zr-based amorphous alloy was decreased due to the permeated hydrogen.

• 한국자기학회지
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• 제4권2호
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• pp.150-153
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• 1994

본 연구에서는 2쌍의 헬름홀쯔코일을 사용하여 비본형 시편의 종방향 및 횡방향으로 자기장 을 인가한 상태에서 열처리한 Co-계 비정질 합금 VITROVAC 6030의 보자력 노이즈를 측정하였다. 시편의 종방향 및 횡방향으로 dc 자기장을 인가한 상태에서 열처리한 시편의 경우, 보자력노이즈는 자화주파수 가 1~100 kHz 범위에서 거의 변화하지 않았으며, 시편의 종방향으로 ac 자기장을 횡방향으로는 dc자기 장을 인가한 상태에서 열처리한 시편의 경우의 보자력 노이즈는 자화주파수의 거듭제곱으로 감소하는 경 향을 보였다. 또한 자구핵형성이 일어날 경우 보자력 노이즈는 크게 증가하며 자화주파수의 거듭제곱으 로 감소하는 경향을 보였다.

• Journal of Magnetics
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• 제21권2호
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• pp.164-167
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• 2016

The effect of the B additions on glass formation and magnetic properties is reported for the $Fe_{(87-x-y)}Co_yTi_7Zr_6B_x$ (x = 2, 4, 6 and y = 35, 40) alloy system. The ribbon samples with the width of 2 mm for each composition were prepared by the melt spinning technique; furthermore, their phase information was obtained from X-ray diffraction. Glass formation and magnetic properties were measured using differential scanning calorimetry and vibrating sample magnetometer respectively. The $Fe_{45}Co_{40}Ti_7Zr_6B_2$ (x = 2 and y = 40) system has the nanocrystalline phase identified as ${\alpha}-Fe$, as well as the amorphous phase, whereas all other alloys are fully amorphous. It is associated with the role of B on the glass formation. The widest supercooled liquid region is obtained as 71 K at x = 4 (both y = 35 and 40). The saturation magnetization decreases with the increase of the amount of the B addition, and the highest value is 1.59 T as x = 2 and y = 35 for this alloy system.

• Journal of Magnetics
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• 제9권2호
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• pp.47-51
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• 2004

Giant magneto-impedance (GMI) effect in zero-magnetostrictive Co-based amorphous ribbons samples in their as-quenched and stress-released states as well as with intentionally induced magnetic anisotropy were investigated. Magnetic and impedance properties of the samples exhibiting different anisotropy were compared and the optimum operation conditions for the studied samples from the view-point of their utilization as a sensor element have been determined. A design of a model of magnetic field sensor and characteristics of the constructed prototype are presented.

• 한국재료학회:학술대회논문집
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• 한국재료학회 2000년도 추계학술발표강연 및 논문개요집
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• pp.173-173
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• 2000

• 한국자기학회:학술대회 개요집
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• 한국자기학회 1999년도 춘계연구발표회 논문개요집
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• pp.86-87
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• 1999

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2000년도 International Symposium on Magnetics The 2000 Fall Conference
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• pp.512-513
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• 2000