• Journal of Magnetics
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• 제10권4호
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• pp.145-148
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• 2005

Effect of vacuum annealing on the microstructures and magnetic properties of $Fe_{84}Si_6B_{10}$ films has been investigated as a function of annealing temperature. X-ray diffraction and transmission electron microscopy were employed to analyze crystallization behavior of the films. Permeability of the films was measured at various frequencies by one-turn coil method. When the films were annealed below 673 K, the coercivity of the films did not change a lot (${\~}$1500 A/m) although the grain size of a crystalline phase in the partially crystallized films increased gradually up to about 16 nm. It then increased rapidly as the films became almost fully crystalline mostly with $\alpha$-(Fe,Si) phase at and above 723 K. On the other hand, the electrical resistivity of the films decreased monotonically with the increase of annealing temperature. The permeabilities of the films annealed at 473${\~}$673 K were all over 1000, showing the optimum value of 3500 at 523 K, and almost constant up to 300 MHz. However, those of the as-deposited and fully crystallized films were lower than 1000 and unstable at the same frequency range.

• Membrane and Water Treatment
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• 제14권1호
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• pp.11-18
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• 2023

This work addresses the development of microfiltration ceramic membrane from alumina using extrusion method. The membranes were sintered at different temperatures ranging between 1000 and 1300℃. The alumina was characterized with thermogravimetric analysis, particle size distribution, X-ray diffraction, Fourier transform infrared spectrometer and scanning electron microscope analysis. Subsequently, the effect of sintering temperature on the membrane properties such as porosity, flexural strength, and pure water permeability was investigated and optimized for the sintering temperature. It is observed that with increasing sintering temperature, the porosity of the membranes decreases and the flexural strength, and pure water permeability of the membranes increase. The uncoated and coated membranes were compared at constant flux mode of filtration. Under the turbidity solution recirculation alone at 100 NTU, trans-membrane pressure (TMP) of uncoated membrane remained constant when the filtration flux was below 121 Lm^-2 h ^-1 , while the coated membrane was 111 Lm_-2 h ^-1 . Although suction pressure increased more rapidly at higher turbidity, coated membrane filtration showed better removal efficiency of the turbidity.

• 한국자기학회지
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• 제3권2호
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• pp.130-134
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• 1993

초급냉법중 단롤법으로 제작한 $Fe_{73.5-X}Co_{X}Cu_{1}Nb_{3}Si_{13.5}B_{9}(x=2,\;4)$ 비정질 합금을 $400~650^{\circ}C$에서 열처리하여 자기적 특성을 조사하였다. $Fe_{71.5}Co_{2}Cu_{1}Nb_{3}Si_{13.5}B_{9}$ 비정질 합금의 최적 열처리 온도는 $550^{\circ}C$이며, 이온도에서 열처 리된 시료의 상대 투자율과 항자력은 1 kHz에서 각각 $1.1{\times}10^{4}$, 0.22 Oe이다. $Fe_{69.5}Co_{4}Cu_{1}Nb_{3}Si_{13.5)B_{9}$의 경우는 $600^{\circ}C$에서 열처리 했을때 상대 투자율과 항자력이 각각 $1.0{\times}10^{4}$, 0.19 Oe로 가장 우수한 연자성 특성을 보였다. X-선 실험결과, 이러한 연자성 특성의 향상은 $\alpha$-Fe(Si) 결정립의 형성에 의한 것임을 확인 할 수 있었으며, 강자성 공명 실험에 의하면 최적 열처리 조건은 공명 흡수선의 반치폭이 급격히 증가하기 직전의 온도임을 알 수 있었다.

• 폴리머
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• 제35권5호
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• pp.402-408
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• 2011

$Na^+$-사포나이트(saponite, SPT) 필름의 유연성을 향상시키기 위해 수용성 고분자인 폴리(비닐 알코올)(poly(vinyl alcohol); PVA)을 다양한 함량(0~10 wt%)으로 사용하여 용액 삽입방법을 통해 SPT 하이브리드 필름을 제조하였다. 본 논문에서는 SPT 하이브리드 필름의 열적 광학적 성질, 모폴로지, 및 가스 투과성 등을 조사하였다. PVA 농도에 따른 SPT 하이브리드 필름의 성질들은 X-선 회절도(XRD), 전계방사형 주사전자현미경(FE-SEM), 시차주사 열량계(DSC), 열중량 분석기(TGA), 열기계 분석기(TMA), 자외선-가시광선(UV-vis.) 흡광도기, 및 산소투과($O_2$TR) 측정기 등을 통해 조사하였다. SPT 하이브리드 필름의 성질들은 PVA의 무게% 농도에 따라 많은 영향을 받았으며, 적은 양의 PVA도 SPT 하이브리드 필름의 유연성을 증가시키기에 충분하였다.

• 한국수소및신에너지학회논문집
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• 제24권1호
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• pp.29-35
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• 2013

A dense mixed ionic and electronic conducting ceramic membrane is one of the most promising materials because it can be used for separation of oxygen from the mixture gas. The $ABO_3$ perovskite structure shows high chemical stability at high temperatures under reduction and oxidation atmospheres. $BaCo_{1-x-y}Fe_xZr_yO_{3-{\delta}}$ (BCFZ) was well-known material as high mechanical strength, low thermal conductivity and stability in the high valence state. Glycine Nitrate Process (GNP) is rapid and effective method for powder synthesis using glycine as a fuel and show higher product crystallinity compared to solid state reaction and citrate-EDTA method. BCFZ was fabricated by modified glycine nitrate process. In order to control the burn-up reaction, $NH_4NO_3$ was used as extra nitrate. According to X-Ray Diffraction (XRD) results, BCFZ was single phase regardless of Zr dopants from y=0.1 to 0.3 on B sites. The green compacts were sintered at $1200^{\circ}C$ for 2 hours. Oxygen permeability, methane partial oxidation rate and hydrogen production ability of the membranes were characterized by using Micro Gas Chromatography (Micro GC) under various condition. The high oxygen permeation flux of BCFZ 1-451 was about $1ml{\cdot}cm^{-2}s^{-1}$. Using the humidified Argon gas, BCFZ 1-433 produced hydrogen about $1ml{\cdot}cm^{-2}s^{-1}$.

• 멤브레인
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• 제15권2호
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• pp.165-174
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• 2005

본 연구에서는 SEBS와 여러 가지의 유기화물로 처리된 MMT type의 clay를 이용하여 SSEBS-clay 하이브리드 막을 용액법으로 제조하였다. clay의 함량은 5 phr로 고정하였다. 용액법을 사용하여 clay를 SEBS에 분산시켰으며, 제조된 SSEBS-clay 하이브리드에서 clay의 특성피크가 완전히 박리되거나 이동하는 XRD 결과로부터 고분자의 clay 층간삽입을 확인하였다. Clay의 종류에 따라서 제조된 SSEBS-clay 하이브리드 막의 가스투과도, 기계적 물성 및 열적 성질을 측정하였다. SSEBS-clay 하이브리드 막은 clay 자체의 도입과 층간거리의 확대로 기체분자의 tortuosity를 증가시켜서 가스투과도를 저하시키는 것을 확인하였다.

• 한국자기학회지
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• 제15권1호
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• pp.12-16
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• 2005

본 연구에서는 비정질 시료 $Fe_{87}Zr_{7}B_{6}$ 에 중성자르 조사시킨 후 자기화의 온도의존성, X-ray 회절과 복소 투자율을 측정하여 중성자 조산 전, 후의 자기적 특성 변화를 보았으며, 다양한 중성자 조사량에 따른 복소 투자율과 자기이력곡선을 측정하여 측정하여 중성자 조사량에 따른 지구벽 운동과 자기화 회전을 보았다. 실험결과 중성자 조사에 의한 지구벽 운동은 감소하였으며, 자기화 회전은 증가 한 것을 볼 수 잇었다. 또한, 자기이완 주파수는 지구벽 운동의 경우 증가하였으며, 자기화 회전에 의한 이완 주파수는 감소하였다. 자기이력곡선의 결과 중성자 조사 후 포화 자기화 값이 감소하는 것을 볼 수 있었는데 이러한 실험 결과로부터 중성자 조사 후 생긴 결함에 의해 지구벽 운동은 억제되었으며, 자기화 회전부분은 증가 한 것을 알 수 있었다.

• Geomechanics and Engineering
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• 제24권6호
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• pp.573-588
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• 2021

The interaction of cracks and water significantly affects the fracture mechanism of rocks. In this study, laboratory tests were conducted using sandstone samples containing a single fissure to explore the hydro-mechanical behaviors in the failure process of pre-cracked rocks. The internal crack characteristics were also analyzed using X-ray CT scanning. The results show that the confining pressure has the greatest effect on the mechanical properties (e.g., strengths, elastic modulus, and Poisson's ratio), followed by the fissure inclination and water pressure. At a lower fissure inclination, the confining pressure may control the type main cracks that form, and an increase in the water pressure increases the number of anti-wing cracks and the length of wing cracks and branch cracks. However, the fracture behaviors of samples with a higher fissure inclination are only slightly affected by the confining pressures and water pressures. The effect of fissure inclination on the internal crack area is reduced with the propagation from the fissure tips to the sample ends. The fissure inclination mainly affects the value of permeability but not affect the trend. The impact of pre-existing fissure on permeability is smaller than that of confining pressure and water pressure.

• 자원리싸이클링
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• 제9권5호
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• pp.11-15
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• 2000

The sample made of $Mn_3O_4$ indicated an excellent frequency dependency for intial permeability and core loss. Moreover the homogeneity of cation configuration in he spinel structure was confirmed by X-ray diffraction analysis. The result of homogeneity of the spinel structural coincided with the analytical results of temperature dependence of magnetization. Furthermore, the influence of manganese oxide as starting material, on homogeneity of spinel structure was examined by using thermogravimetry-differential thermal analysis. It may be concluded that the reaction between $Mn_3O_4$ and Fe-Zn oxide mixture proceeds at fist in all combination of manganese oxide and oxie mixture, and then Mn-Zn-Fe spinel was formed.

• Food Science and Biotechnology
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• 제15권6호
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• pp.925-930
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• 2006

Chitosan-based nanocomposite films were prepared using a solution intercalation method incorporating varying amounts of organically modified montmorillonite (Cloisite 30B) from 0 to 30 wt%. The nanocomposite films prepared were optically clear despite a slight decrease in the transmittance due to the spatial distribution of nanoclay. X-ray diffraction patterns indicated that a certain degree of intercalation or exfoliation formed when the amount of clay in the film was low and that microscale tactoids formed when the clay content in the sample was high (more than 10 wt%). The tensile strength (TS) of the chitosan film increased when the clay was incorporated up to 10 wt% and then decreased with further increases in the clay content of the film. The elongation at break (E) increased slightly upon the addition of low levels of clay up to 5 wt% and then decreased with further increases in the amount of the clay in the film. The water vapor permeability (WVP) decreased exponentially with increasing clay content. The water solubility (WS) and swelling ratio (SR) of the nanocomposite films decreased slightly, indicating that the water resistance of the chitosan film increased due to the incorporation of the nanoclay.