• Progress in Superconductivity and Cryogenics
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• v.11 no.3
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• pp.60-64
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• 2009

We investigated an operating characteristic of linear-type magnetic flux pump (LTMFP) as a current compensator under the various conditions. In order to explain the mechanism of the LTMFP, the magnetic behavior of superconducting Nb foil according to pumping actions should be understood. In this paper, the magnetic field analysis of superconducting Nb foil installed in LTMFP has been performed based on the three-dimensional finite element method (3D FEM). Through the simulation analysis, the normal spot region on the superconducting Nb foil is found to be enhanced swiftly over about 20 Hz. The simulated finding agreed with an analytical estimation based on the phenomenon of magnetic diffusion.

• Proceedings of the KOSOMBE Conference
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• v.1995 no.11
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• pp.124-127
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• 1995

Due to the self-diffusion of nuclear spins, the edge of phantoms is enhanced in the magnetic resonance imaging (MRI), especially in the case of microscopy [1]. According to several published works, theory has been established that the edge enhancement is caused by the motion narrowing around bounded regions due to diffusions of nuclear spins during data acquisition. It is found, however, that the signal decreases due to the diffusion attenuation and image is distorted as edge of the image is sharpened. In this paper, we wilt investigate this signal loss during data acquisition and its effects on image, i.e., image edge enhancement due to the diffusion phenomenon. This result is new and different from the previously discussed edge enhancement due to the diffusion, namely, by motion narrowing effect or spin bouncing effect at the boundary.

• Journal of Magnetics
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• v.21 no.1
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• pp.51-56
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• 2016

The microstructure and magnetic properties of HDDR-treated powders after grain boundary diffusion process (GBDP) with Nd-Cu alloy at different temperatures have been studied. The variation of GBDP temperature had multifaceted influences on the HDDR-treated powders involving the microstructure, phase composition and magnetic performance. An enhanced coercivity of 16.9 kOe was obtained after GBDP at $700^{\circ}C$, due to the modified grain boundary with fine and continuous Nd-rich phase. However, GBDP at lower or higher temperature resulted in poor magnetic properties because of insufficient microstructural modification. Especially, the residual hydrogen induced phenomenon during GBDP strongly depended on the GBDP temperature.

• Progress in Superconductivity and Cryogenics
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• v.11 no.2
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• pp.20-24
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• 2009

In order to explain the operating characteristics of LTMFP in a wide range of driving frequency, an analytical equation that takes into account the detailed behavior of the normal spot is necessary. In this paper, based on the phenomenon of magnetic diffusion of the superconductor we modified the theoretical equations for pumping action in LTMFP. The modified equations explained well the pumping actions under the different load magnets. These results are important to explain the pumping tendency of the LTMFP according to driving frequency.

• Journal of Magnetics
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• v.16 no.3
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• pp.225-228
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• 2011

Magnetic properties and Rockwell hardness of 1Cr-0.5Mo steel have been investigated as a function of isothermal aging time. Our results showed that coercivity, hysteresis loss and Rockwell hardness in the aged samples decreased as aging time increased. This phenomenon was analyzed using optical microscopy and scanning electron microscopy. A significant diffusion of Cr and Mo atoms formed $M_2C$ and $M_7C$ carbides, lowering the matrix strength. $M_2C$ and $M_7C$ carbides partially segregated inside grains, diffused into grain boundaries, and finally resulted in a soft ferrite matrix and a hard grain boundary. The magnetic and mechanical softening of the matrix is likely to govern the properties of the sample more than the hardening of the grain boundary by carbide precipitations.

• Journal of Korean Neurosurgical Society
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• v.54 no.2
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• pp.139-141
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• 2013

Presented here is a 36-year-old male with arterial hypertension who developed brainstem edema and intracranial hemorrhage. Magnetic resonance scan revealed diffuse brainstem hyperintensity in T2-weighted and fluid-attenuated inversion-recovery images, with an increase in apparent diffusion coefficient values. After a reduction in blood pressure, rapid resolution of the brainstem edema was observed on follow-up. The patient's condition was thus interpreted as hypertensive brainstem encephalopathy. While many consider this a vasogenic phenomenon, induced by sudden, severe hypertension, the precise mechanism remains unclear. Prompt recognition and aggressive antihypertensive treatment in such patients are essential to prevent permanent or life-threatening neurologic injury.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.61.1-61.1
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• 2013

Turbulence is a common phenomenon in astrophysical fluids such as the interstellar medium (ISM) and the intracluster medium (ICM). In turbulence studies it is customary to assume that fluid powered by an energy injection on a single scale. However, in astrophysical fluids, there can be many different driving mechanisms that act on different scales simultaneously. In this work, we assume multiple energy injection scale (2${\surd}$12 and 15