• 열처리공학회지
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• 제17권2호
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• pp.78-86
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• 2004

Effects of the annealing parameters on the formation of ferrites transformed at low temperatures were studied in cold-rolled ultra low carbon steels with niobium and/or chromium. Niobium and chromium were found to be effective in the formation of the low temperature transformation ferrites. The low temperature transformation ferrites more easily formed when both higher annealing temperature and longer annealing time, allowing substitutional alloying elements to distribute between phases, are in combination with faster cooling rate. It was found from EBSD study that the additions of niobium or chromium resulted in the increase in the numbers of high angle grain boundaries and the decrease in those of the low angle grain boundaries in the microstructures. Both granular bainitic ferrite and bainitic ferrite were characterized by the not clearly etched grain boundaries in light microscopy because of the low angle grain boundaries.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.172-175
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• 2006

Effects of deformation at austenite non-recrystallization region and cooling rate on the microstructure and mechanical properties of low carbon (0.06 wt. %) high strength low alloy steels have been investigated. Average grain size decreased and polygonal ferrite transformation promoted with increasing deformation amount due to increase of ferrite nucleation site. As cooling rate increased, the major microstructure changed from polygonal ferrite to acicular ferrite and the fraction of M/A constituents gradually increased. Discontinuous yielding occurred in highly deformed specimen due to the formation of polygonal ferrite. However, small grain size of highly deformed specimen caused lower ductile-to-brittle transition temperature than slightly deformed specimen.

• 한국세라믹학회지
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• 제34권5호
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• pp.453-460
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• 1997

Sr-ferrite having magnetoplumbite structure is similar to Ba-ferrite in magnetic characteristics, but better magnetic characteristics for using motor application. To improve remanence magnetic flux density(Br) and coercive force(iHc), it is necessary that sintered ferrites must have high density and grain size less than 1 $\mu$m. By varying n values in SrO.nFe2O3 basic composition, calcination temperature, and BaO addition, Sr-ferrite powder and sintered specimen was prepared. The n values, calcination temperature, and BaO addition affected secondary phase formation, particle size, and particle shape. BaO addition enhanced Fe2O3 secondary phase and hexagonal shape particle. Fe2O3 phase reduced sintered density which greatly decreased Br.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.149-154
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• 2000

In this paper, we studied the relation between addition of carbon and electromagnetic wave absorbing properties of ferrite-rubber composite. The ratio of carbon was 7 wt%. As s result, it has been shown that the electromagnetic wave absorbing properties of ferrite-rubber composite are changed by the addition of carbon in composite. And, we can control electromagnetic wave absorbing properties of ferrite-rubber composite by the using of carbon.

• 한국안광학회지
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• 제7권1호
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• pp.35-38
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• 2002

자외선과 전자파를 동시에 차단하는 선글라스렌즈를 제작하기 위하여 유리기판 위에 자성재료인 페라이트 박막을 페라이트 도금법으로 제작하였다. 이들은 모두 스피넬 구조의 단일상임을 확인할 수 있었으며, 육안으로 관찰할 때 거울면과 같은 광택을 가졌으며, 손톱으로 긁었을 때 흠집이 생기지 않는 경도를 보였다. 페라이트는 400nm 부근에서부터 급격히 투과율이 떨어져 자외선을 차단하는데 효과적인 양상을 보이고 있다. 타사제품과 비교하여 자외선 차단효과는 크게 떨어지지 않으며, 전자파 차단효과가 있는 페라이트를 코팅한 선글라스를 착용함으로서 유해전자파와 자외선을 차단하는 효과를 얻을 수 있을 것이다.

• 한국전자파학회논문지
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• 제14권12호
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• pp.1329-1334
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• 2003

폐 처리된 Ba 페라이트를 사용하여 GHz 대역용 전파흡수체를 개발하였다. 도전 손실재인 카본의 첨가에 따른 전파흡수능의 변화와 시편 제작시 제작온도 변화에 따른 전파흡수능의 변화를 조사하였다. 이와 같은 실험을 통하여 GHz 대역용 Ba 페라이트 전파흡수체를 개발하는데 있어 카본의 첨가가 매우 유효함을 알았으며, 시편의 제작온도 또한 우수한 전파흡수체를 개발하는데 있어 반드시 고려되어야 함을 밝혔다.

• 한국전자파학회논문지
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• 제14권12호
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• pp.1276-1282
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• 2003

SMT 타입의 페라이트 비드(ferrite bead)는 전원단에서 발생되는 잡음(noise)이 회로 소자로 유입되는 것을 막기 위해 사용되는 소자로 병렬 캐패시터(capacitor)와 직렬 인덕터(inductor) 및 저항(resistor)을 이용하여 등가 모델화된다. 이와 같은 간단한 페라이트 비드의 등가 모델은 광대역 범위에서 측정 결과와 일치하지 않는다. 본 논문에서는 광대 역(50 MHz∼3 GHz)에서 정확한 페라이트 비드의 모델을 제시하고 페라이트 비드가 있을 때와 없을 때 전원단 잡음의 회로 소자에 미치는 영향을 고찰하였다.

• 한국전기전자재료학회논문지
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• 제19권9호
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• pp.883-887
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• 2006

In order to attain high-rate deposition of Mn-Zn ferrite thin film for soft magnetic underlayer in perpendicular magnetic recording media, a reactive sputtering using powder-metal targets under the mixture gas of Ar and $O_{2}$ was performed. It was succeeded that Mn-Zn ferrite films with (111) crystal orientation were deposited on Pt(111) underlayer without any annealing process. The film revealed 3.4 kG of 4 ${\pi}Ms$, 70 Oe of coercivity. The deposition rate of the new method was 16 times as high as that of the conventional method using ferrite target.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1996년도 추계학술대회 논문집
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• pp.326-329
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• 1996

In order to synthesize Ba-ferrite fine particles by molten salt method and inhibit the abnormal grain growth of sintered specimen, KCI anti NaCl were added to basic composition to 50% by weight, and added 1 male% of $SiO_2$ to control the shape of Ba-ferrite particles. $H_{c}$ and $M_{r}$ were decreased when F $e^{3+}$ was substituted with $Co_{2+}$ and $Ti_{4+}$ from x=0 to x=1.0 in $BaFe_{12-2x}$ $Ti_{x}$ $Co_{x}$ $O_{19}$ , and 1 mole% $SiO_2$ increased the size but shortened c-axis of hexagonal ferrite. Seeds added in Ba-ferrite particle effected inhibition of abnormal grain growth during sintering.ing.g.

• 반도체디스플레이기술학회지
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• 제4권3호
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• pp.35-38
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• 2005

Due to high permeability of the ferrite cores, the characteristics of the inductively coupled plasma(ICP) are expected to be greatly improved. We investigated the effect of the ferrite cores on conventional inductively coupled plasma. It was observed that the current and voltage in the ICP antenna are slightly decreased and the power transfer efficiency is increased. However, due to eddy current and hysteresis loss, plasma density in the ICP with the ferrite cores is not increased. It seems that the ICP with the ferrite cores at low frequency ($\∼$100 kHz) will be greatly improved since the losses at the low frequency can be negligible.