• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05a
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• pp.92-95
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• 2003

전력선 통신용 LC 공진필터에 사용되는 Ni-Zn 페라이트를 제조하기 위해 $Ni_{0.8}Zn_{0.2}Fe_{2}O_{4}$를 기본조성으로 첨가제 $Bi_{2}O_{3}$, CaO와 x (co mol 비)를 변화시켜 전자기적 특성을 조사하였다. $Bi_{2}O_{3}$ CaO가 첨가됨으로써 균일한 입자성장과 입계에 고저항층이 형성되어 주파수 손실이 감소하였으며, $Ni_{0.8-x}Zn_{0.2}Co_{x}Fe_{2}O_{\delta}$의 기본조성에 Co의 함량을 증가시키면 x = 0.05에서 투자율 75, 공진주파수 20MHz의 특성을 나타내고 결정 입자 크기와 같은 구조적 특성에는 영향을 거의 미치지 않지만 전자기적 특성에는 영향을 미친다. 또한, $Ni_{0.75}Zn_{0.2}Co_{0.05}Fe_{2}O_{4.017}$ 조성의 페라이트 코어의 발열량은 큐리온도 이하에서 일어난다.

• Proceedings of the Korean Magnestics Society Conference
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• 2014.11a
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• pp.154-154
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• 2014

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.1927-1928
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• 2014

• Journal of the Korean Applied Science and Technology
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• v.15 no.4
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• pp.79-85
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• 1998

$Cu_xFe_{3-x}O_4$ catalyst and $Zn_xFe_{3-x}O_4$ catalyst were synthesized by the air oxidation method with various C(II) and Zn(II) weights. Activated catalysts decomposed carbon dioxide to carbon at $350^{\circ}C$, $380^{\circ}C$, $410^{\circ}C$ and $440^{\circ}C$. The value of carbon dioxide decomposition rate for $Cu_{0.003}Fe_{2.997}O_4$ and $Zn_{0.003}Fe_{2.997}O_4$ catslysts than was better catalysts. The decomposed rate of the catalysts is about 85%${\sim}$90%. The reaction rate constant(4.00 $psi^{1-{\alpha}}/min$) and activation energy(2.62 kcal/mole) of $Cu_{0.003}Fe_{2.997}O_4$ catalyst are better than $Zn_{0.003}Fe_{2.997}O_4$

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.569-572
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• 2003

전력선 통신용 LC 공진필터에 사용되는 Ni-Zn 페라이트를 제조하기 위해 Ni0.8Zn0.2Fe2O4를 기본조성으로 선택하고 x (Co mol 비)를 변화시켜 전자기적 특성을 조사하였다. $Bi_2O_3$ CaO가 첨가됨으로써 균일한 입자성장과 입계에 고저항층이 형성되어 주파수 손실이 감소하였으며, $Ni_{0.8-x}Zn_{0.2}Co_xFe_2O_{\delta}$의 기본조성에 Co의 함량을 증가시키면 x = 0.05에서 투자율 75, 공진주파수 20 MHz의 특성을 나타내고 결정 입자 크기와 같은 구조적 특성에는 영향을 거의 미치지 않지만 자기이방성 변화에 따라 전자기적 특성에는 영향을 미친다. 또한, $Ni_{0.75}Zn_{0.2}Co_{0.05}Fe_2O_{4.017}$ 조성의 페라이트 코어의 발열량은 큐리온도 이하에서 일어난다.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.285-291
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• 2004

As a part of assessment of the structural material for the molten salt handling system, corrosion behavior of Inconel 718, X-750, Haynes 75 and Haynes 263 alloys in the molten salt of LiCl-Li$_2$O-O$_2$was investigated in the range of temperature; $650^{\circ}C$, time; 24~168h, $Li_2O$; 3wt%, mixed gas; Ar~10%$O_2$. In the molten salt of LiCl-$Li_2O-O_2$, the order corrosion rate was Haynes 263 ＜ Haynes 75 ＜ Inconel X-750 ＜ Inconel 718. Haynes 263 alloy showed the highest corrosion resistance among the examined alloys. Corrosion products of alloys were as fellows: Haynes 75: $Cr_2O_4$, $NiFe_2O_4$, $LiNiO_2$, $Li_2NiFe_2O_4$, Inconel 718; $Cr_2O_4$, $NiFe_2O_4$, Haynes 263; $Li(Ni,Co)O_2$, $NiCr_2O_4$, $LiTiO_2$, Inconel X-750; $Cr_2O_3$, $NiFe_2O_4$,$FeNi_3$, (Al,Nb,Ti)$O_2$. Haynes 263 showed local corrosion behavior and Haynes 75, Inconel 718 and Inconel X-750 showed uniform corrosion behavior.

• Journal of the Korean Magnetics Society
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• v.15 no.2
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• pp.96-99
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• 2005

Phase transition from normal- to inverse-spinel structure has been observed for $Fe_xCo_{3-x}O_4$ thin films as the Fe composition (x) increases from 0 to 2. The samples were fabricated as thin films by sol-gel method on Si(100) substrates. X-ray diffraction measurements revealed a coexistence of two phases, normal and inverse spinel, for $0.76{\le}x{\le}0.93$. The normal-spinel phase is dominant for $x{\le}0.55$ while the inverse-spinel phase for $x{\ge}l.22$. The cubic lattice constant of the inverse-spinel phase is larger than that of the normal-spinel phase. For both phases the lattice constant increases with increasing x. X-ray photoelectron spectroscopy measurements revealed that both $Fe^{2+}$ and $Fe^{3+}$ ions exist with similar strength in the x=0.93 sample. Conversion electron $M\ddot{o}ssbauer$ spectra measured on the same sample showed that $Fe^{2+}$ ions prefer the octahedral $Co^{3+}$ sites, indicating the formation of the inverse-spinel phase. Analysis on the measured optical absorption spectra for the samples by spectroscopic ellipsometry indicates the dominance of the normal spinel phase for low x in which $Fe^{3+}$ ions tend to substitute the octahedral sites.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.331-334
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• 2001

In this study, the magnetic properties for Ni-Zn ferrite were investigated as the function of $Co_3$ $O_4$ additive contents which was predicted to improve the resonance frequency. Toroid specimens with the composition of N $i_{0.8-x}$Z $n_{0.2+x}$F $e_2$ $O_4$(x = 0, 0.05, 0.1, 0.15) ferrites were preparation by conventional ceramic processing technique. The maximum resonance frequency of 19.905 MHz and the permeability of 90.88 in 10 MHz were attained to the N $i_{0.8}$Z $n_{0.2}$F $e_2$ $O_4$with $Co_3$ $O_4$0.3 wt%. Both of the permeability in 10 MHz and the resonance increased to 107.11 and 19.005 MHz respectively for the N $i_{0.8}$Z $n_{0.2}$F $e_2$ $O_4$with $Co_3$ $O_4$wt% than the N $i_{0.8}$Z $n_{0.2}$F $e_2$ $O_4$/ with the free $Co_3$ $O_4$composition.composition.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.1
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• pp.25-33
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• 1998

We have studied the reduction of NO by propane over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution by substitution of metal into A or B site of perovskite oxides. In addition, the reaction conditions, such as temperature, $O_2$ concentration, space velocity have been studed. In the $LaCoO_3$ type catalyst, the partial substitution of Ba, Sr into A site enhanced the catalytic activity in the reduction of NO. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3(x=0 \sim 1.9)$ catalyst, the partial substitution of Fe into B site enhanced the conversion of NO, but excess amount of Fe decreased the conversion of NO. The surface area and catalytic activity of perovskite catalysts prepared by malic acid method showed higher values than those of solid reaction method. In the $La_{0.6}Sr_{0.4}Co_{1-x}Fe_xO_3$ catalyst, the conversion of NO increased with increasing $O_2$ concentration and contact time. The introduction of water into reactant feed decreased the catalytic activity.

• Resources Recycling
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• v.2 no.2
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• pp.9-15
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• 1993

In this study, magnetite($Fe_3$$O_4$) from the converter dust of the Kwangyang steel making factory has been recove-red by means of the magnetic separation and the sedimentation column. The magnetite recovered from the dust is used for the preparation of Sr-ferrite instead of hematite. The results obtained in this study as follows : 1. The converter EP dust of the Kwangyang steel making factory are composed of $\alpha$-Fe, ($Fe_3$$O_4$) wustite etc. Magnetite in the converter EP dust is recovered by using sedimentation column and plastic bonding magnet. 2. It was confirmed that Sr-ferrite synthesis could be possible without oxidizing roasting of the magnetite. The steps of Sr-ferrite formation are proposed as follows : I$SrCO_3$ $+Fe_3$O$_4$+1/2(1-X)$O_2$longrightarrow$\alpha$ $-Fe _2$$O_3$ $+SrFeO _3$\ulcorner+$CO_2$II. $5.5\alpha$ $-Fe_2$$O_3$ $+SrFeO_3$\ulcornerlongrightarrowSrFe\ulcornerO\ulcorner+1/2(1/2-X)$O_2$3. By using magnetite from the dust insted of hematite, the hard Sr-ferrite magnet of (B.H)\ulcorner=2.64MGOe in the magnetic characteristics was succesfully prepared.