• Resources Recycling
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• v.23 no.5
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• pp.3-11
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• 2014

Calcium ferrite is more effective binder for making sintered ore and flux for steel making because of it's low melting temperature. In this Study, calcium ferrite was made by calcinating method in the cement manufacturing process in order to reduce manufacturing costs and increase productivity. Limestone and calcination sludge were used as CaO source, steelmaking sludge, blast furnace dust and iron ore were used as Fe-bearing raw materials. The sintering temperature of specimens is in the range of $950{\sim}1170^{\circ}C$. For Calcium ferrite can be used 'binder for making sintered ore' or 'flux for converter/electric furnace' with a low melting point properties, the raw material characteristics and sintering properties were investigated.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.56-56
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• 2009

AISI 316L 스테인리스강에 새롭게 디자인한 서로 다른 3가지 응고모드를 가진 와이어로 FCAW(Flux Cored Arc Welding)을 하였다. 각각의 3가지 와이어는 Pseudobinary phase diagram에 따라 AF, FA, F모드를 가졌다. 미세조직은 $Cr_{eq}/Ni_{eq}$이 증가할수록 델타 페라이트 함량이 증가하였으며, 초정 상의 경우 초정 오스테나이트에서 초정 페라이트로 변태하였고, 연성저하균열의 민감도가 감소하였다. 연성저하균열은 이동결정립계의 형상에 따라 좌우되며, 미량의 페라이트를 함유한 오스테나이트에서는 페라이트가 핀(Pin) 역할을 제대로 하지 못하여 직선형태의 이동 결정립계 따라 입계 미끄러짐의 메커니즘을 통해 전파되었으며, 곡선형태의 이동 결정립계에서는 델타 페라이트가 핀 역할을 하여 역할을 하여 구속 상태에서 응력집중을 막고 응력을 분산시켜 균열이 전파되는 것을 방해하여 균열이 발생되지 않았다.

• Applied Chemistry for Engineering
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• v.3 no.4
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• pp.722-729
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• 1992

Mg-and Zn-ferrites having spinel structure, a kind of complex oxides showing the advantageous properties of constituently single metal oxides, were selected to find a relationship between their catalytic activities in the dehydrogenation of ethylbenzene to styrene and the catalytic properties. For the structural and physical analyses of ferrites, XRD, BET, DTA, XPS, TEM and TPD methods were employed. Potassium added to the catalyst played a role of bifunctional promoter which brought the electronic effect as well as the structural one for the increment of particle dispersion. K-addition decreased acid strength of the catalyst by neutralization and increased its acidity. In the dehydrogenation of ethylbenzene, K-addition let the selectivity to styrene be constant throughout the reaction by the proper acid strength of the ferrite for the reaction, which could be obtained from the neutralization of strong acid sites by potassium.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.500-504
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• 2009

NiCuZn Ferrites, known as preventing EMI/EMC, were prepared and their properties were investigated based on the chemical composition ratio, sintering temperature, and mean particle size. The NiCuZn ferrite made of $Fe_2O_3$ 49.0 mol%, NiO 9.0 mol%, CuO 8.0 mol%, ZnO 34.0 mol% could be applied at the largest range of electromagnetic wave. The optimal calcination and sintering temperature were $900^{\circ}C$ and $1080^{\circ}C$, respectively. The electromagnetic wave loss capacity of its mean particle size $1.12{\mu}m$ was superior to others examined.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.4
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• pp.470-480
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• 2011

Analog ferrite phase shifters based on rectangular waveguides which are used as component of passive phased array system have high power handling capability, but it is heavy and has high cost to fabricate. In this paper, we propose an analog ferrite phase shifter using substrate integrated waveguide(SIW), which has low cost and is easy to fabricate because it uses printed circuit board(PCB) process. The proposed structure is fabricated by using centeral dielectric material removal for inserting a ferrite bar. The measured results show that the proposed structure has not only $5.1^{\circ}$/mm phase variation but also return loss variation under 12.9 dB. Therefore, it is expected that the proposed phase shifter can plays an role to reduce weight and to has low cost on the phased array system.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.30-36
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• 2005

Recently, It has been reported that the spin sprayed ferite film shows better magnetic properties at high frequeny that the ferrite by co-firing over $800^{\circ}C$ . Besides, there is no limitation to select the substrate materials because it can be processed with relatively low temperature below $100^{\circ}C$. Therefore, we fabricated film inductor as a passive device for DC-DC converter by a use of spin sprayed embedded form was completed by via hole process of pad opening. Saturation magnetization of 0.61 T and real part of permeability of 110 were obtained in Ni-Zn ferrite. In addition, inductance of 1.52 ${\mu}H$, quality factor of 24.3 at 5 MHz were measured with spiral 16 turn inductor. The rated current of inductor was 863 mA.

• Journal of Navigation and Port Research
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• v.26 no.5
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• pp.525-528
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• 2002

The proposed EMC filter composed with feed-through capacitors and ferrite beads of high permeability was prepared which satisfy the EMC standard for a wide-band noise signal in the frequence of 10 MHz to 1.5 GHz in power supply line. The optimum structure of ferrite bead was found by calculating the load effect of ferrite beads. As a result, the filter showed excellent differential- and common-mode noises filtering characteristics above 30dB in the frequency band from 10 MHz to 1.5 GHz. The immunity characteristics are improved more than 10 to 30 dB over the frequency band from DC to 1.8GHz.

• Applied Chemistry for Engineering
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• v.22 no.2
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• pp.185-189
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• 2011

In this work, nano-sized M-ferrites (M=Co, Ni, Cu, Zn) for the decomposition of carbon dioxide were synthesized by the chemical co-precipitation. From the thermogravimetric analysis, it was clear that the maximum weight loss of each sample took place below $350^{\circ}C$. High temperature calcination resulted in more systematic crystallines, smaller specific surface area and larger particle size. An analysis by FTIR in the range of $375{\sim}406cm^{-1}$ revealed the presence of chelates at the octahedral site, which implies the formation of spinel structure in the ferrites. The current work showed that a $500^{\circ}C$ is the optimum heat treatment temperature of metal ferrites for $CO_2$ decomposition reaction.

• Korean Journal of Materials Research
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• v.6 no.1
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• pp.40-48
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• 1996

고주파 저손실 재질로 사용되고 있는 Mn-Zn 페라이트의 제조공정 중 소결조건과 Ta2O5첨가가 Mn-Zn 페라이트의전력손실에 미치는 영향에 대해서 연구하였다. 등조성선을 따라 냉각하기 위하여 컴퓨터를 사용해서 정확하게 산소분압을 조절하였으며 적절한 등조성선을 선택함으로써 보다 좋은 손실특성을 얻을 수 있었다. CaO-SiO2 첨가계에 Ta2O5를 0ppm에서 400ppm으로 변화시켜 가며 첨가하였으며, Ta2O5 가 400ppm 첨가되었을 경우 균일한 grain 성장과 더불어 낮은 전력손실을 나타내었다. 온도에 상응하는 상평형 산소분압을 정확히 맞춰 냉각할 경우 전력손실 최소값이 질소 분위기에서 냉각시킨 시편보다 높은 온도쪽으로 이동됨도 확인할 수 있었다.

• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.52-56
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• 2009

The design method of a four-port stripline circulator with a single ferrite disk is proposed using Green's function method. The four-port circulator gives the flexibility of the design of the communication system. Two cascaded three-port circulators has been used as a four-port circulator. However, if a four-port circulator with a single ferrite disk replace the present four-port circulator, then it will give less weight and volume and so has the advantage in satellite application.