• Proceedings of the Korean Magnestics Society Conference
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• 1998.10a
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• pp.22-23
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• 1998

• Journal of the Korean Magnetics Society
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• v.7 no.1
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• pp.19-24
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• 1997

Composition and process conditions for low temperature sintered NiCuZn ferrites were investigated, so as to fabricate multilayered chip inductor. The$Fe_2O_3$ deficiency for low temperature sintering was decreased with NiO contents of NiCuZn ferrites. The permeability of NiCuZn ferrites can be controlled in the range of 12~562 with the variation of NiO and $Co_3O_4$ contents. The $Q_{max} $ frequency of NiCuZn ferrites was decreased from 50 MHz to 3 MHz linearly with permeability increase from 60 to 560. The relation between the $Q_{max}$ frequency(Y) and permeability(X) of NiCuZn ferrites was expressed with the following empirical equation, logY=4.2-1.4logX.

• Proceedings of the Korean Magnestics Society Conference
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• 1999.10a
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• pp.96-97
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• 1999

• Proceedings of the Korean Magnestics Society Conference
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• 1999.04a
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• pp.30-31
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• 1999

• Journal of the Korean institute of surface engineering
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• v.39 no.3
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• pp.115-120
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• 2006

The codeposition behavior of WC particles from an additive-free nickel sulfate and sulfamate solution has been investigated. Electroplating of Ni/WC composites was carried out at different current density with variation of WC particle size. The Guglielmi adsorption mechanism is applied to the electroplating of the fine WC in Ni matrix. The contents of WC in Ni composite coating were increased both by increasing current density and WC concentration in the bath. The hardness of Ni/WC composite coating at low current density is higher than that at high current density since finer WC particles dispersed through the coating. The codeposition behaviors of Co coated WC particles were also investigated. Conducting layer of particles promoted the codeposition behavior of Ni/WC-Co composite coatings.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.2
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• pp.99-107
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• 2009

This study produced a design curve and fatigue limit for a variation in volume ratio and reduction ratio of TiNi/Al composites. In many cases, stress-life curve does not indicate fatigue limit, so it was presented by probabilistic-stress-life curve. Goodman diagram was used to analyze the fatigue strength of materials with a finite life determined by repeated load and the fatigue strength of endurance limit with an infinite life. The fatigue experiment was conducted using the scenk-type plane bending specimen in same shape. The result of the fatigue test, which had been conducted under consistent stress amplitude, was examined. (i) The optimal condition for TiNi/Al in accordance with hot pressing (ii) Impacts of fatigue limit caused by a variation in reduction ratio and volume ratio of TiNi/Al composites (iii) Probability distribution for fatigue limit of TiNi/Al2024 and TiNi/Al6061.

• Proceedings of the KIEE Conference
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• 1997.07d
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• pp.1355-1357
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• 1997

In this study, the ferrite/rubber composite microwave absorbers mixed Ni-Zn ferrite and $Ni_2Y$ ferroxplana were prepared in order to control matching condion. The variation of the material constants($\dot{\varepsilon}$, $\dot{\mu}$) and microwave absorbing characteristics were investigated with various ferrite mixing ratio. The material constants of ferrite/rubber composite microwave absorber could be controlled by variation ferrite mixing radio. The matching frequency and thickness could be controlled with various ferrite mixing ratio.

• Journal of Magnetics
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• v.1 no.1
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• pp.37-41
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• 1996

The frequency dependence of complex permeability for various NiCuZn ferrites was investigated. The variation of complex permeability for NiCuZn ferrites can be presented as a form of a semi-circle, so called the Cole-Cole plot, and the relaxation phenomena were explained with various shapes of the plots. The relaxation time $\Upsilon$ was calculated from $f_rx$, which is a relaxation frequency at ${\mu"}_{max}$. Relations between anisotropy field $H_A$ and relaxation time $\Upsilon$, initial permeability $\mu_i$ and $H_A$ were plotted to identify the frequency dependence of complex permeability.lity.

• Journal of the Korean institute of surface engineering
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• v.46 no.4
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• pp.175-180
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• 2013

Carbon nanofilaments (CNFs) could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under thermal chemical vapor deposition system. Ni powders were used as the catalyst for the formation of the CNFs. During the initial deposition stage, the initiation of the CNFs on the Ni catalyst was investigated. The geometries of the as-grown CNFs on Ni catalyst were strongly dependent on the size and/or the shape of Ni catalyst. Small size catalyst (<150 nm in diameter) gives rise to the unidirectional growth of the CNFs. On the other hand, large size catalyst (150~500 nm), the bidirectional growth of the CNFs could be observed. Particularly, the well faceted parallelogram-shaped Ni catalyst could give rise to the bidirectional growth of the CNFs having the symmetrically opposite direction. Eventually, these bidirectional growths of CNFs were understood to form the well-developed carbon microcoils (CMCs). Based on these results, the optimal shape and the size of the Ni catalyst to form the CMCs were discussed.

• Journal of the Korean Magnetics Society
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• v.5 no.1
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• pp.21-26
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• 1995

The systematic variation of complex permeability and complex permittivity and their relationship with micro-wave absorbing properties are investigated in sintered Ni-Zn ferrites of non-stoichiometric composition. The specirrens of ${(Ni_{0.5}Zn_{0.5}O)}_{1-x}(Fe_{2}O_{3})_{1+x}$ spinels were prepared by a conventional ceramic processing technique. In the present study. complex permeability and permittivity can be controlled by the variation of ${\alpha}-Fe_{2}O_{3}$ contents in the spinel lattice. The primary effect of the excess ${\alpha}-Fe_{2}O_{3}$ is to increase the dielectric constant. while the notable decrease of magnetic loss is observed in the iron-deficient ferrites. The results suggest that the matching fre-queocyand matching thickness could be controlled by the variation of ${\alpha}-Fe_{2}O_{3}$ contents in the Ni-Zn ferrite.