• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.499-503
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• 2002

This work focuses on eliminating tiny particles from the coolant in a nuclear pipe line by using a permanent magnet on the exterior surface of the pipe. This method have some merits compared with the many applied methods and is expected to be applied to most of the pipe lines in the nuclear plant. For instance in this method, a ring is attached to the exterior surface of the pipe, so that it does not affect the inflows directly. Further, the cost needed in the initial build-up of the facility is low.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.30 no.2
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• pp.111-114
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• 2017

In this research, the development of fabrication technique of bulk YBaCuO superconductors for application was studied. In fluence of $BaZrO_3$ addition on magnetization characteristics of thermal pyrolysis textured YBaCuO superconductor was investigated. Fine $BaZrO_3$ particle were dispersed within the textured YBaCuO matrix by means of the thermal pyrolysis processing. Magnetic levitation force for YBaCuO superconductors were obtained using Nd-B-Fe permanent magnet, at 77 K and at the magnetic field from 0 to 5.3 K gauss. In the unadded superconductor and 5 wt% $BaZrO_3$ addition, anomalous magnetization behavior, which is characterized by the intermediate magnetic field, was observed at 77 K. Critical current density was about few hundreds $A/cm^2$ and the magnetic characteristics increased slightly by addition of $BaZrO_3$ powder. Maximum magnetic force was obtained in the YBaCuO superconducting bulk with 3 wt.% $BaZrO_3$ addition.

• Korean Journal of Materials Research
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• v.12 no.3
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• pp.215-219
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• 2002

For the purpose of annihilating tumor in body, hematoporphyrin as a photosensitizer was coated onto magnetic particles of $Fe_3O_4$ prepared by coprecipitation which could be concentrated around the tumor by magnetic field. The photosensitizer was applied differently before, during and after adsorbing the 1st surfactant on the particles. Its added amount was $5{\times}10^{-4}/mol$, and the coating reaction proceeded at temperatures of 60, 70 and 8$0^{\circ}C$. The amounts of photosensitizer coated on the magnetic particles were obtained by calculating an optical density with the maximum UV spectrum. As a result of the UV analysis, the coating amount of photosensitizer increased with higher reaction temperatures. When applied at 8$0^{\circ}C$ after adsorbing the 1st surfactant, the photosensitizer was coated with a maximum value of $3.8{\times}10^{-3}/mo1/$\ell$$. The TGA analysis revealed that the ferrofluids included the particles of 30.115 g/$\ell$. It was suggested that the magnetite particles was coated with photosensitizer of $1.26{\times}10^{-4}/mo1/g$. A small-sized device for magnetic field and light emission was designed, in which LED sheets coverts the permanent magnet of Nd-Fe-B. The LED sheet was connected in series circuit and also protected with a silicon tube. The power was supplied with rechargable battery of 9V and 100-120mA.

• Journal of the Korean Magnetics Society
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• v.5 no.5
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• pp.366-371
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• 1995

High performance magnetic materials are characterized by the combination of outstanding magnetic properties and optimized microstructures, e.g., nanocrystalline composites of multilayers and small particle systems. The characteristic parameters of the hysteresis loops of these materials vary over more than a factor of $10^{6}$ with optimum values for the coercive field of several Tesla and permeabilities of $10^{6}$. Within the framework of the computational micromagnetism (nanomagnetism) using the finite element method the upper and lower bounds of the coercive field of different types of grain ensembles and multilayers have been determined. For the case of nanocrystalline composites the role of grain size, exchange and dipolar coupling between grains and the degree of grain alignment will be discusses in detail. It is shown that the largest coercivities are obtained for exchange decoupled grains, whereas remanence enhancing requires exchange coupled grains below 20 nm. For composite permanent magnets based on $Nd_{2}Fe_{14}B$ with an amount of ~ 50% soft $\alpha$-Fe-phase coercivities of ${\mu}_{0}H_{c}=0.75\;T$, a remanence of 1.5 T and an energy product of $400\;kJ/m^{3}$ is expected. In nanocrystalline systems the temperature dependence of the coercivity is well described by the relation ${\mu}_{0}H_{c}=(2\;K_{1}/M_{s}){\alpha}-N_{eff}{\mu}_{0}M_{s}$, where the microstructural parameters $\alpha$ and $N_{eff}$ take care of the short-range perturbations of the anisotropy and $N_{eff}$ is related to the long-range dipolar interactions. $N_{eff}$ is found to follow a logarithmic grain size size dependence ${\mu}_{0}H_{c}=(2\;K_{1}/M_{s}){\alpha}-N_{eff}(\beta1nD){\mu}_{0}M_{s}$. Several trends how to achieve the ideal situation $\alpha$->1 and $N_{eff}$->1->0 will be discussed.