• 한국자기학회지
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• 제10권1호
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• pp.7-10
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• 2000

Co계 비정질합금을 400~46$0^{\circ}C$에서 열처리 한 후 냉각조건에 따른 자기특성의 변화를 조사하였다 42$0^{\circ}C$에서 30분 열처리 한 뒤 큐리점까지 노냉 후 수냉 시킨 경우 초투자율이 수냉 또는 노냉 했을 때보다 60-100% 정도 증가했다. 냉각속도에 따른 자기적 특성 변화를 내부음력 및 이온쌍의 규칙도(ordering) 관점에서 고찰하였다

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.966-972
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• 2009

Soil-aggregate system in pavement foundations exist in unsaturated conditions. However, change in water content on foundation layers due to joint and structural cracks during rainfall may cause problems like layer deformations or partial settlements. Therefore, a need exist to evaluate the infiltration and drainage capacity of soil-aggregate foundation system under both saturated and unsaturated conditions. To do that, a laboratory soil-water characteristic curve and permeability under unsaturated conditions are assessed to establish hydraulic properties of geomaterials and limited numerical analysis are performed respectively. As a result, it was found that suction profiles and drainage process was greatly influenced by the initial suction of soil-aggregate system at the time of infiltration, soil water characteristics curves, and hysteresis effects.

• 한국세라믹학회지
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• 제34권6호
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• pp.561-568
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• 1997

The effects of sintering temperature and oxygen partial pressure on the electromagnetic properties of Mn-Zn ferrites were investigated. The grain increased with increasing temperature. The power loss at 100 kHz was decreased, while the power loss at 500 kHz was increased as the grain size increased with sintering temperature. Sintering with low oxygen partial pressure at 115$0^{\circ}C$ resulted in high density and initial permeability, and decreased the power loss at 100 kHz and 500 kHz. The oxygen partial pressure lower than 10-2 atm. during heating, significantly suppressed the hysteresis loss. However, the oxygen activity did not affect the grain size of sintered cores.

• 한국자기학회지
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• 제5권1호
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• pp.15-20
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• 1995

연자성재료인 Mn-Zn 페라이트에 미량의 첨가물로 CaO(0.1 mol%), NiO(0.0~6.0 mol%) 그리고 CoO(0.0~0.8 mol%) 첨가하여 20 종류의 시료를 공침법으로 제조하여, 첨가물의 첨가량에 따른 Mn-Zn 페라이트의 자기적 성질을 연구하였다. NiO, CoO의 첨가량이 증가함에 따라 초기투자율은 감소하고, 반면 Curie 온도는 증가하였다. 보자력$(H_{c})$, 포화자화$(B_{s})$ 및 자기이력손실$(W_{h})$은 NiO의 첨가량이 증가함에 따라 증가하는 것으로 나타났다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.784-785
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• 2006

Co-based amorphous powder was produced by a new atomization process "Spinning Water Atomization Process (SWAP)", having rapid super-cooling rate. The composition of the alloys was ($(Co_{0.95}Fe_{0.05})_{1-x}Cr_x$)$_{75}Si_{15}B_{10}$ (x=0, 0.025, 0.05, 0.075). The powders became the amorphous state even if particle size was up to about $500{\mu}m$. The coercive force of powders was about 0.35 - 0.7 Oe. Furthermore, Co-based amorphous powder cores with glass binders were made by cold-pressing and sintering methods. The initial permeability of the core in the frequency range up to 100 kHz was about 110, and the core loss at 100 kHz for Bm = 0.1 T was $350kW/m^3$.

• 한국세라믹학회지
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• 제28권3호
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• pp.225-233
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• 1991

In this study, we tried to find out the appropriate synthetic condition and magnetic properties of Ni-Zn ferrite {(NixZn1-x)Fe2O4} powders (where X=0, 0.1, 0.2, 0.3, ……0.9, 1). Ferrite powders were prepared by wet-direct method at 86℃ for 6hrs from FeCl36H2O, NiCl26H2O, and ZnCl2. The powders of (NixZn1-x)Fe2O4 (where X=0.4, 0.5, 0.6) have a good crystallinity, but the other ferrite powders consist of crystal and precursor ferrite. The ferrite powder's lattice constant is increased when ratio of ZnO contant is increased in the ferrite composition. And initial permeability was measured after sintering, result indicated regular pattern except (Ni0.4Zn0.6)Fe2O4 when the frequency were changed 10KHz to 10MHz.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.284-286
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• 1999

The 7-dial inductive voltage divider (IVD) which is divided the in put voltage precisely upto 10-7 were fabricated by using the toroidal cores made of super-mumetal strips of 0.025 mm thick and special decade switches. The cores ate of the initial permeability of 200,000 and magnetic flux density of 0.5 T. The in phase and quadrature ratio errors are evaluated to less than ${\pm}4{\times}10^{-7}$ and ${\pm}5{\times}10^{-6}$ rad. respectively. The fabrication techniques used are more discussed in this paper.

• 산업기술연구
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• 제11권
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• pp.85-98
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• 1991

A numerical study was performed to investigate characteristics of one-dimensional consolidation of soft clay. Results of consolidation tests with the remolded normally consolidation clay of having a very high initial void ratio were analyzed by using the numerical technique of finite difference method based on the finite strain consolidation theory, to evaluate consolidational characteristics of soft clay under surcharges on the top of clay. On the other hand, a numerical parametric study on soft clay consolidated due to its self-weight was also carried out to find its effect on one-dimensional consolidation. Terzaghi's conventional consolidation theory, finite strain consolidation theories with linear and non-linear interpolation of effective stress - void ratio - permeability relation were used to analyze the test results and their results were compared to each other to figure out the difference between them. Therefore, the validity of theories was assessed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1990년도 추계학술대회 논문집
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• pp.71-77
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• 1990

This paper is studied on the sintering characteristics of Ni-Zn ferrites. The specimen ferrites was composed of 20 mol% NiO, 30mol% ZnO, 50 mol% Fe$_2$O$_3$, and 0.0025 mol%, 0.005 mol%, 0.01 mol% Nb$_2$O$\_$5/, Bi$_2$O$_3$, V$_2$O$\_$5/, wee used as minor additives. Sintering was carried out at 1100$^{\circ}C$. As results from the experiments, the high value of initial permeability of 6X10$^2$∼9X10$^2$ can be achieved at 500KHz∼1000KHz. The value of loss factor 1X10￣$^2$∼2X10$^2$ can be achieved at 500KHz∼1000KHz. The lowest 1/(${\mu}$XQ) value was obtained in the specimen with the addition of 0.005mol% fracyion for V$_2$O$\_$5/.

• 한국표면공학회지
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• 제45권5호
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• pp.188-192
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• 2012

The hetero junction on dielectrics and ferrite for LTCC was prepared by using NiCuZn ferrite. The shrinkage behaviour of ferrite tapes in combination with a dielectric tape was investigated. The characteristics of NiCuZn ferrite were investigated using XRD (X-ray diffractometer), Dilatometer, FE-SEM (Field emission scanning electron microscope), EDS (Energy dispersive spectrometer). NiCuZn ferrite calcined at $700^{\circ}C$ had a good apparent density and initial permeability of magnetic properties. The shrinkage rate of the NCZF700 ferrite and dielectric material was similar. The multilayer revealed dense, uniform morphologies with excellent interface quality. Diffusion of hetero junction such as dielectric and ferrite was not occuring at $900^{\circ}C$.