• Membrane Journal
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• v.14 no.4
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• pp.312-319
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• 2004

The porous SiO$_2$-B$_2$O$_3$ membrane was prepared from Si(OC$_2$$H_5$)$_4$-($CH_3$O)$_3$B-C$_2$$H_5$OH-$H_2O$ system by sol-gel method. In order to investigate the characteristics of this membrane, we examined that using BET, IR spectrophotometer, X-ray diffractometer, SEM and TEM. At $700^{\circ}C$, the surface area of SiO$_2$-B$_2$O$_3$ membrane was 354.398 $m^2$/, the median pore diameter was 0.0048 ${\mu}{\textrm}{m}$, and the particle size of SiO$_2$-B$_2$O$_3$ membrane was 7 nm. The separation properties of the gas mixture ($H_2$/$N_2$) through the SiO$_2$-B$_2$O$_3$ membrane was studied as a function of pressure. The real separation factor($\alpha$) of SiO$_2$-B$_2$O$_3$ membrane for $H_2$/$N_2$ gas mixture was 4.68 at 155.15 cmHg and $25^{\circ}C$. The real separation factor($\alpha$), head separation factor($\beta$) and tail separation factor((equation omitted)) were increased as the pressure of permeation cell increased.

• Korean Journal of Crystallography
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• v.16 no.2
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• pp.102-106
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• 2005

The crystal structure of the title compound has been analyzed by single crystal X-ray diffraction method. The compound crystallized in the triclinic space group $P\bar{1}$ with a=11.300(6) ${\AA}$, c=18.716(10) ${\AA}$, ${\alpha}=82.833(10)^{\circ}$, ${\beta}=83.042(11)^{\circ}$, ${\gamma}=66.139(10)^{\circ}$, $V=2162(2)\;{\AA}^{3}$, Z=2 and R1=0.661 for 10578 unique reflections. The four $C_{5}Me_{5}$ planar groups from a tetrahedron with a mean dihedral angle $70.92(9)^{\circ}$ among them and the $Ti_{4}O_{6}$ cage sits at the center of the tetrahedron. Each Ti atom in the $Ti_{4}O_{6}$ cage is bonded by three bridging oxygen atoms and coordinated by a $C_{5}Me_{5}$ ligand with a mean distance $2.067{\AA}$ from Ti atoms to the centroids of the four five-membered rings. Two oxygen atoms facing each other in $Ti_{4}O_{6}$ cage are $4.051(3){\AA}$ away in average.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.253-253
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• 2010

Rice straw was pretreated with aqueous ammonia in order to enhance enzyme digestibility. Soaking in ammonia aqueous (SAA) was conducted with 15% ammonia, at $60^{\circ}C$. for 24 h. Optimization of both saccharification conditions and enzyme loading of SAA rice straw was carried out. Especially enzyme loading test was performed using statistical method. Moreover proton beam irradiation (PBI) was also performed to overcome the problem which inhibit the enzyme digestibility at 1-25 kGy doses with 45 MeV of beam energy. Optimal condition for enzymatic saccharification was follows; pH 4.8, $50^{\circ}C$, 60 FPU of enzyme activity, 1:4 ratio of celluase and ${\beta}$-glucosidase. Also, optimal doses of PBI on rice straw and SAA-treated rice straw for efficient sugar recovery were found to be 3 kGy, respectively. When saccharification was performed with optimal condition, glucose conversion yield was 89% of theocratical maximum in 48 h, and 3 kGy of PBI was applied to SAA-treated rice straw, approximately 90% of the theoretical glucose yield was obtained in 12 h. The results of X-ray diffractometry (XRD) support the effect of both SAA and PBI on sugar recovery, and scanning electron microscopy (SEM) images unveiled the physical change of the rice straw surface since rugged rice straw surface was observed.

• Journal of the Korean Chemical Society
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• v.51 no.3
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• pp.240-243
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• 2007

The eight coordinated yttrium(III) complex Y(tpb)3(H2O)2 (Htpb=4,4,4-Trifluoro-1-phenyl-1,3-butanedione) has been synthesized and structurally characterized by X-ray diffraction method. The coordination polyhedron of Y(tpb)3(H2O)2 has a dodecahedron. The angle between two trapezia, Y-O2-O1-O5-O6 and Y-O4-O3-O8-O7, is 89.59°. The O1-O5 and O3-O8 distances are 2.965 and 2.995 A whereas the O2-O6 and O4-O7 distances are 4.256 and 4.403 A.

• Journal of the Korean Chemical Society
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• v.13 no.2
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• pp.131-136
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• 1969

The crystal structure of rubidium hydrogen carbonate has been determined by single crystal X-ray diffraction method. the crystals are monoclinic with a = 15.05 $\AA$, b = 5.83 $\AA$, c = 4.02 $\AA$, and $\beta$ = $107^{\circ}.$ There are four chemical units per unit cell and the space-group was fixed as $C2-C^3_2$. Patterson and trial-and-error methods gave the approximate structure and its refinements were made by two-dimentional Fourier summation. The Co3 group is planar with tshhe C-O distances of 1.32 $\AA$, 1.32 $\AA$, and 1.33 $\AA$ within experimental error and the two $CO_3$ groups are linked together to form a complex anion [$H_2C_2O_6$] with the O-H${\cdot}{\cdot}{\cdot}$O distance, 2.53 $\AA.$ Two molecules of $RbHCO_3$ make the dimer structure with two hydrogen bonds. The values of reliability factor for $F_{(hol)}$, $F_{(hko)}$and $F_{(okl)}$are 0.15, 0.15 and 0.17 respectively. Each rubidium ion has eight oxygen neighbours with the Rb-O distances of 2.84~3.11 $\AA.$.

• Transactions of the Korean hydrogen and new energy society
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• v.12 no.4
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• pp.247-255
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• 2001

The relation between the deformation and the geometrical shape, and the effect of cold work on the hydrogen absorption behavior in palladium were investigated. The Pd specimens used were plates and wires as cold worked and annealed states. The palladium plates and wires were loaded with hydrogen by electrochemical method. Experimental analyses were carried out through X -ray diffraction, micrometer measurement and decimal balance measurement. As the results, it is found that the effect of cold work on hydrogen absorption capacity was relatively small. The deformation of the palladium plates in thickness direction is larger than in other lateral directions whereas the palladium wires showed the same deformation ratio in all radius directions because of the circular distribution of coexisting $\alpha$ and $\beta$ phases. The products of plastic deformation such as slip lines and voids etc. were observed abundantly in all specimens although the specimens had undergone only once of a hydrogen absorption and desorption.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.79-80
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• 2013

The purpose of this study was to investigate $2^{nd} $nanotube formed surface observation of the Ti-25Ta-xZr alloys using ATO(anodic titanium oxide) technique. Ti-25Ta-xZr alloy was anodized in 1M $H_3PO_4$ electrolytes containing 0.8 Wt. % NaF at room temperature. After formation of nanotube was achieved out, nanotube was eliminated, and then anodization was carried out repeatedly. The microstructures, phase transformation, and morphology of nanotubular Ti-25Ta-xZr alloys and process of nanotube growth by using ATO method was examined by optical microscopy (OM), X-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The ${\alpha}$ phase and ${\beta}$ phases were affected to form the second nanotube morphology of Ti-25Ta-xZr alloys.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.129-132
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• 1999

A new single solution source MOCVD technique for the deposition of YBCO film has been developed, using a ultrasonic atomizer to feed the precursors into an evaporation zone. This method being investigated as a basis for future long wire fabrication, for example the electric power use, the magnatic applications, etc.. YBCO films were prepared on MgO(100) substrate, using mixture of Y, Ba, and Cu ${\beta}$ -diketonate chelate was dissolve in tetrahydrofuran as a solution sources. X-ray diffraction measurement indicated that the thin film grew epitaxially with the c-axis orientation perpandicular to the surface of the surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.641-646
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• 2004

We report the changes of the microwave reflection coefficients S$_{11}$ of copper(II)-phthalocyanine (CuPc) thin films by using a near-field microwave microscope(NSMM) in order to understand the phase transition of CuPc. For a NSMM system, a high-quality microstrip resonator coupled with a dielectric resonator was used. CuPc thin films were prepared on the pre-heated glass substrates using a thermal evaporation method. The reflection coefficients S$_{11}$ of CuPc thin films were changed by the dependence on the substrate pre-heating temperatures. By comparing reflection coefficient S$_{11}$ and crystal structures, we found the phase transition of CuPc thin films from $\alpha$-phase to $\beta$-phase at the substrate heating temperature 200 $^{\circ}C$./TEX>.

• Journal of the Korean institute of surface engineering
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• v.34 no.2
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• pp.161-168
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• 2001

A Thermal Barrier Coating (TBC) can play an important role in protecting parts from harmful environments at high temperatures such as oxidation, corrosion, and wear in order to improve the efficiency of aircraft engines by lowering the surface temperature of the turbine blade. The TBC can increase the life span of the product and improve the operating properties. Therefore, in this study the mechanical and thermal properties of the TBC such as oxidation, fatigue and shock at high temperatures were evaluated. A samples of a bond coat (CoNiCrAlY) produced by the High Velocity Oxygen Fuel (HVOF) and Low Pressure Plasma Spray (LPPS) method were used. The thickness of the HVOF coating layer was approximately $450\mu\textrm{m}$ to 500$\mu\textrm{m}$ and the hardness number of the coating layer was between 350Hv and 400Hv. The thickness of the LPPS coating was about 350$\mu\textrm{m}$ to 400$\mu\textrm{m}$ and the hardness number of the coating was about 370Hv to 420Hv. The X-ray diffraction analysis showed that CoNiCrAlY coating layer of the HVOF and LPPS was composed of the $\beta$and ${\gamma}$phase. After the high temperature oxidation test, the oxide scale with about l0$\mu\textrm{m}$ to 20$\mu\textrm{m}$ thickness appeared at the coating surface on the Al-depleted zone was observed under the oxide scale layer.