• Journal of the Korean Magnetics Society
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• v.13 no.3
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• pp.109-114
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• 2003

The purpose of this study Is to investigate the effect of $V_2$O$_{5}$ addition on the microstructures and magnetic properties of 7.7${\times}$4.5${\times}$1.0 mm sized multi-layer chip inductors prepared by the screen printing method using 0∼0.5 wt％ $V_2O_{5}$-doped NiCuZn ferrite pastes. With increasing the $V_2O_{5}$ content, the exaggerated grain growth of ferrite layers was developed due to the promotion of Ag diffusion and Cu segregation into the grain boundaries oi ferrites, which affected significantly the magnetic properties of the chip inductors. After sintering at $900^{\circ}C$, the inductance at 10 MHZ of the 0.5 wt％ $V_2O_{5}$-doped chip inductor was 3.7 ${\mu}$H less than 4.2 ${\mu}$H of the 0.3 wt% $V_2O_{5}$-doped one, which was thought to be caused by the residual stress at the ferrite layers increased with the promotion of Ag diffusion and Cu segregation. The quality factor of the 0.5 wt% $V_2O_{5}$-doped chip inductor decreased with increasing the sintering temperature, which was considered to be caused by the electrical resistivity of the ferrite layer decreased with the promotion of Ag/cu segregation at the grain boundaries and the growth of the mean grain size of ferrite due to exaggerated grain growth of ferrite layers.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2004.12a
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• pp.27-34
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• 2004

This experiment was carried out to examine the effects of morphology on properties of La-Co substituted SrM ferrite. The magnetic properties of calcined and sintered materials varied with the substitutional amount of La and Co elements in Sr-ferrite. In the substituted SrM ferrite, the atomic fraction x of La is directly related to the mole ratio n of iron oxide and the atomic fraction y of Co by equation x=2ny. The HcJ values of the calcined powder were about 270 kA/m and 240 kA/m with x=0.3 and K=0.2, respectively at stoichiometriy, n=6.0. Crystallites of the sintered material were grown with a plate shape, and their size decreased with increasing mole ratios. Such a shape was caused by the initial state of crystallite formed after calcination. In case of x=0.3 and n=6.0, Br was 415 mT and HcJ was 355 kA/m, and in x=0.2 and n=6.0, Br was 410 mT and HcJ was 370kA/m. The squareness in 2nd quarter of BH curve with x=0.2 was smoothly improved compared with x=0.3

• Journal of the Korean Ceramic Society
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• v.38 no.12
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• pp.1155-1161
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• 2001

Yittrium Iron Garnet(YIG) has been used as an important material in the circulator/isolator which is used in RF communication system, mobile phone, adn satellite broadcasting, etc. In this study, we investigated the microstructural and magnetic properties of YIG ferrites with the sintering temperature and additives. We fabricated the YIG ferrites substituted with Ca, In, V by the traditional ceramic sintering method at 1250$\^{C}$, 1275$\^{C}$, 1300$\^{C}$ and 1325$\^{C}$. Powders were granulated by using a spray dryer. Crystallographic and microstructural properties were measured by using XRD and SEM. Magnetic properties were measured by using a VSM for saturation magnetization (4$\pi$M$\_$s/) and FMR (Ferromagnetic Resonance) experiment for ferromagnetic resonance line width (△H). The YIG ferrite, Y$\_$1.6/Ca$\_$1.4/Fe$_4$V$\_$0.7/In$\_$0.3/O$\_$12/, sintered at 1300$\^{C}$, showed higher saturation magnetization and lower ferromagnetic resonance line width than any other sintering temperatures.

• Journal of the Korean Magnetics Society
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• v.24 no.3
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• pp.81-85
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• 2014

Nano-sized Ba-ferrite, Ni-Zn ferrite and $BaFe_{12}O_{19}/Ni_{0.5}Zn_{0.5}Fe_2O_4$ nanocomposite ferrite were prepared by sol-gel combustion method. Nanocomposite was calcined at temperature range of $600{\sim}900^{\circ}C$ for 1 h. According to the diffraction patterns, hard/soft nanocomposite was indicated to the coexistence of the magnetoplumbite structural $BaFe_{12}O_{19}$ and spinel $Ni_{0.5}Zn_{0.5}Fe_2O_4$ and agree with the standard data (JCPDS 10-0325). The particle size of nanocomposite turn out to be less than 90 nm. The nanocomposite ferrite shows a single-phase magnetization behavior, implying that the hard magnetic phase and soft magnetic phase were well exchange-coupled. The specific saturation magnetization ($M_s$) of the nanocomposite is located between hard ($BaFe_{12}O_{19}$) and soft ferrite ($Ni_{0.5}Zn_{0.5}Fe_2O_4$). The remanence (Mr) of nanocomposite ferrite is much higher than that for the individual $BaFe_{12}O_{19}$ and $Ni_{0.5}Zn_{0.5}Fe_2O_4$ ferrite. $(BH)_{max}$ is increased, generally.

• Journal of the Korean Ceramic Society
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• v.28 no.7
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• pp.556-560
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• 1991

The behavior of Ni-Zn ferrite/Mn-Zn ferrite composite electromagnetic absorber was investigated. The imaginary part of complex permeability of the composite was higher than that of either ferrite alone at all frequency range (50∼1400MHz) studied. The difference, which was pronounced in low frequency range, was reached the maximum value when the composite consisted of constituent ferrites with equal amount. Since the thickness in inversely proportional to the imaginary part of complex permeability for the ferrite absorber, it was possible to reduce the thickness of electromagnetic absorber by employing a composite of two different ferrites.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.279-282
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• 2004

본 논문에서는 자기저항 센서를 이용하여 자율주행 시스템에서 필요로 하는 자석의 종류에 따른 자계의 특성을 분석하였다 분석결과 거리에 따라 자계의 특성이 변화하고, 자석에 근접할수록 자계의 변화가 급격하게 나타난다. 센서가 자석에서 멀어질수록 지자계의 값에 가까워진다 또한 페라이트자석 보다 네오디뮴 자석의 자계특성이 우수함을 보였다.

• Electronics and Telecommunications Trends
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• v.9 no.1
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• pp.149-157
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• 1994

위성통신, 이동통신 등의 통신 시스템의 보급이 활발해짐에 따라 통신용 부품의 기술 개발이 한층 시급해지고 있다. 본 고에서는 이동통신용 단말기 및 기지국 RF 회로의 필수적인 부품인 아이솔레이터, 서큘레이터 등에 사용되는 기본 재료인 페라이트의 재료적 성질, 제조 공정 및 각국의 기술 현황에 대해 알아보고자 한다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.10a
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• pp.218-224
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• 1998

본 논문에서는 컬러 모니터용 전자관(CDT; Color Display Tube)의 편향 요크(DY; Deflection Yoke)의 제조 공정상 오차가 발생시키는 컨버전스의 오차를 보정하기 위하여 붙이는 페라이트 박판(Ferrite Sheet)의 위치를 결정하는 규칙을 생성하는 박판을 붙여야 하는지 판단한다. 이를 러프 집합 이론을 이용하여 컨버전스 값을 조건부 속성으로, 페라이트 박판의 위치를 판단부 속성으로 하여 판단 테이블을 만들고 이때 발생하는 몇 가지 문제를 해결하여 최소화된 규칙을 찾아내는 방안을 제안한다.

• Ceramist
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• v.17 no.3
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• pp.38-49
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• 2014

• Ceramist
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• v.17 no.3
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• pp.27-31
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• 2014