• Applied Chemistry for Engineering
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• v.8 no.4
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• pp.679-684
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• 1997

The major constituents in spent FCC catalysts are Si, Al, Fe, Ti, alkali metals and some others. The spent catalyst is also composed small amounts of rare metals such as Ce, Nd, Ni and V. The selective adsorption and concentration of Ce and Nd from the leaching solution of spent FCC catalysts with sulfuric acid($0.25mol/dm^3$) were carried out by the column method with a chelate resin having a functional group of aminophosphoric acid type. Ce and Nd were separated from eluate liquor containing Al, Nd and V by the precipitation process with oxalic acid. Vanadium is purified from chloride ion coexistance by solvent extraction, employing tri-n-octyl phosphine oxide as extractant with Al in the raffinate solution. Rare metals with the purity of 99 percent were obtained from the spent FCC catalyst.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.477-477
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• 2008

For more than three decades, the gate dielectrics in CMOS devices are $SiO_2$ because of its blocking properties of current in insulated gate FET channels. As the dimensions of feature size have been scaled down (width and the thickness is reduced down to 50 urn and 2 urn or less), gate leakage current is increased and reliability of $SiO_2$ is reduced. Many metal oxides such as $TiO_2$, $Ta_2O_4$, $SrTiO_3$, $Al_2O_3$, $HfO_2$ and $ZrO_2$ have been challenged for memory devices. These materials posses relatively high dielectric constant, but $HfO_2$ and $Al_2O_3$ did not provide sufficient advantages over $SiO_2$ or $Si_3N_4$ because of reaction with Si substrate. Recently, $HfO_2$ have been attracted attention because Hf forms the most stable oxide with the highest heat of formation. In addition, Hf can reduce the native oxide layer by creating $HfO_2$. However, new gate oxide candidates must satisfy a standard CMOS process. In order to fabricate high density memories with small feature size, the plasma etch process should be developed by well understanding and optimizing plasma behaviors. Therefore, it is necessary that the etch behavior of $HfO_2$ and plasma parameters are systematically investigated as functions of process parameters including gas mixing ratio, rf power, pressure and temperature to determine the mechanism of plasma induced damage. However, there is few studies on the the etch mechanism and the surface reactions in $BCl_3$ based plasma to etch $HfO_2$ thin films. In this work, the samples of $HfO_2$ were prepared on Si wafer with using atomic layer deposition. In our previous work, the maximum etch rate of $BCl_3$/Ar were obtained 20% $BCl_3$/ 80% Ar. Over 20% $BCl_3$ addition, the etch rate of $HfO_2$ decreased. The etching rate of $HfO_2$ and selectivity of $HfO_2$ to Si were investigated with using in inductively coupled plasma etching system (ICP) and $BCl_3/Cl_2$/Ar plasma. The change of volume densities of radical and atoms were monitored with using optical emission spectroscopy analysis (OES). The variations of components of etched surfaces for $HfO_2$ was investigated with using x-ray photo electron spectroscopy (XPS). In order to investigate the accumulation of etch by products during etch process, the exposed surface of $HfO_2$ in $BCl_3/Cl_2$/Ar plasma was compared with surface of as-doped $HfO_2$ and all the surfaces of samples were examined with field emission scanning electron microscopy and atomic force microscope (AFM).

• Transactions on Electrical and Electronic Materials
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• v.3 no.1
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• pp.4-8
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• 2002

The typical mold method for FED (field emission display) fabrication is used to form a gate electrode, a gate oxide layer, and emitter tip after fabrication of a mold shape using wet-etching of Si substrate. However, in this study, new mold method using a side wall space structure was developed to make sharp emitter tips with the gate electrode. In new method, gate oxide layer and gate electrode layer were deposited on a Si wafer by LPCVD (low pressure chemical vapor deposition), and then BPSG (Boro phosphor silicate glass) thin film was deposited. After then, the BPSG thin film was flowed into the mold at high temperature in order to form a sharp mold structure. TiN was deposited as an emitter tip on it. The unfinished device was bonded to a glass substrate by anodic bonding techniques. The Si wafer was etched from backside by KOH-deionized water solution. Finally, the sharp field emitter array with gate electrode on the glass substrate was formed.

• Journal of Powder Materials
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• v.13 no.2 s.55
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• pp.144-149
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• 2006

In this research we tried to make nano-sized TiNx by using planetary milling, and we made the composites double layered of titanium and nano-sized TiNx by using spark plasma sintering apparatus after mixing with the different ratio of pure titanium powder, and they were heat treated at $850^{\circ}C$ for 30 minutes. The crystal structures of nano-sized TiNx powders and the composites were analyzed by X-ray diffraction (XRD). The microstructures of the powders were analyzed by using scanning electron microscopy (FESEM) and the 40-50 nm size of nano-sized TiNx particle on the surface of agglomerated particles was investigated. With increasing the ratio of nano-sized TiNx of the composites, the microvickers hardness of the composites was increased.

• Resources Recycling
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• v.4 no.1
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• pp.12-19
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• 1995

This study was carried out to remove the iron and impurities usmg hydrocyclone and HGMS for recycling of sludge from the granite stone cutting and polishing industrγ in the basic of chemi떠1 analysis and minerallogical investigation. This sludge consist of 70.9% $SiO_2$ 13.6% $Al_2O_3$ and It also contained 2.52% of $Fe_2O_7$ and 0.29% of $TiO_2$, as a main impurities to decrease the whiteness. As the result of hydrocyclone experiment, It was very good condition that are 100~150 g/l of sludge amount, 2.0~ 2.5 mm of underflow nozzle size, and 1.2~1.6 kg/$\textrm{cm}^2$ of pressure for 85% sludge product with the $-37{\mu}\textrm{m}$ size. $Fe_2O_3$ and $TiO_2$, contents by treatment of HGMS were decreased with 0.65% and 0.07% each at 10,000 gauss of magnetic field strength, and addih$\upsilon$n of Sodium tripolyphosphate as a dispersant was effected to get low grade F Fe,Ol and TiO, concentrate. PhYSIcal properties of this stone sludge product were showed 58.5% of whiteness, 1 13.4% of firing shrinkage and 3.0812 $\textrm{m}^2$/g of specific surface area.

• Bulletin of the Korean Chemical Society
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• v.16 no.11
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• pp.1109-1112
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• 1995

Bis(silyl)alkylbenzenes such as bis(1-sila-sec-butyl)benzene (1) and 2-phenyl-1,3-disilapropane (2) were prepared in high yields by reduction of the corresponding chlorosilanes with LiAlH4. The dehydropolymerization of 1 and 2 was carried out with group 4 metallocene complexes generated in situ from Cp2MCl2/Red-Al and Cp2MCl2/n-BuLi (M=Ti, Hf), producing two phases of polymers. The TGA residue yields of the insoluble polymers were in the range of 64-74%. The molecular weights of the soluble polymers produced ranged from 700 to 5000 (Mw vs polystyrene) and from 500 to 900 (Mn vs polystyrene). The dehydropolymerization of 1 and 2 seemed to initially produce a low-molecular-weight polymer, which then underwent an extensive cross-linking reaction of backbone Si-H bonds, leading to an insoluble polymer.

• KIEE International Transactions on Electrophysics and Applications
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• v.11C no.2
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• pp.18-22
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• 2001

The thin films of high permitivity in ferroelectric materials using a capacitor are applied to DRAMs and FRAMs. (Ba, Sr)TiO$_3$ thin as ferroelectric materials were prepared by the sol-gel method and made by spin-coating on the Pt/Sio$_2$/Si substrate at 4,000 [rpm] for 10 seconds. The structural characteristics of the surface were analyzed by fractal dimension. The thickness of BST ceramics thin films was about 260∼280 [nm]. The property of the leakage current was stable with 10-9∼10-11[A] when the applied voltage was 0∼3[V]. BST thin films ha low leakage current properties when fractal dimension was low and a coating area was high.

• Conservation Science in Museum
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• v.27
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• pp.67-90
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• 2022

A C-46 transport aircraft, which can be thought of as a large cultural heritage item from the modern period, was subjected to paint analysis and conservation treatment in preparation for its exhibition. The C-46 is the first aircraft ever dispatched to overseas combat zones by the Korean Air Force and carried out missions during the Vietnam War. The aircraft is mainly made of aluminum and shows signs of corrosion on its surface, including pitting and etching, as well as gray and white powdery attachments. In the analysis of the paint, diatomite(SiO₂·nH₂O) was confirmed in the red paint, titanium dioxide(TiO₂) was identified in the white paint, black iron oxide(Fe₃O₄) was detected in the black paint, and colcothar(Fe₃O₄) mixed with putty was confirmed in the blue paint. Infrared spectroscopy revealed the use of alkyd resin in the paint on the main body and nitrocellulose in the Taegeuk pattern. During the conservation treatment, mechanical cleaning, such as sanding, was conducted to remove paint and varnish from the surface. Corrosion was removed by sanding and cleaning with chemical solvents, and new paints and varnishes were applied. Through the paint analysis and conservation treatment, the aircraft was made available for exhibition in a stable condition.

• Parasites, Hosts and Diseases
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• v.52 no.3
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• pp.281-285
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• 2014

Ticks were collected from 35 animals from 5 provinces and 3 metropolitan cities during 2012. Ticks also were collected by tick drag from 4 sites in Gyeonggi-do (2) and Jeollabuk-do (2) Provinces. A total of 612 ticks belonging to 6 species and 3 genera were collected from mammals and a bird (n=573) and by tick drag (n=39). Haemaphyalis longicornis (n=434) was the most commonly collected tick, followed by H. flava (158), Ixodes nipponensis (11), Amblyomma testudinarium (7), H. japonica (1), and H. formosensis (1). H. longicornis and H. flava were collected from all animal hosts examined. For animal hosts (n>1), the highest Tick Index (TI) was observed for domestic dogs (29.6), followed by Siberian roe deer (17.4), water deer (14.4), and raccoon dogs (1.3). A total of 402 H. longicornis (adults 86, 21.4%; nymphs 160, 39.8%; larvae 156, 38.9%) were collected from wild and domestic animals. A total of 158 H. flava (n=158) were collected from wild and domestic animals and 1 ring-necked pheasant, with a higher proportion of adults (103, 65.2%), while nymphs and larvae only accounted for 12.7% (20) and 22.2% (35), respectively. Only 7 A. testudinarium were collected from the wild boar (6 adults) and Eurasian badger (1 nymph), while only 5 I. nipponensis were collected from the water deer (4 adults) and a raccoon dog (1 adult). One adult female H. formosensis was first collected from vegetation by tick drag from Mara Island, Seogwipo-si, Jeju-do Province.

• Journal of Industrial Technology
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• v.23 no.A
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• pp.199-206
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• 2003

The charcoal-encapsulated methyl silica microcapsules were prepared by a O/W microemulsion sol-gel method, and the adsorption properties on aquatic humic acid were investigated. The capsules prepared were spherical, $100{\sim}1000{\mu}m$ in size. The size distribution was controllable by adjusting the size of charcoal powder, charcoal/methyl silica ratio, and agitating speed in O/W sol-gel process. Adsorption efficiency of charcoal for aquatic humic acid was decreased after encapsulation by methyl silica shell. The decreased adsorption efficiency can be dependent on the decrease of the BET surface area and pore volume after encapsulation. Diffusion properties of humic acid through the capsule shell also played an important role on adsorption efficiency. Therefore, the reasonable target pollutants for the capsules can be VOC or odor molecules which can overcome diffusion barrier through shell of capsules in air condition. Functionalization methods for the charcoal-encapsulated $CH_3(SiO)_n$ microcapsules by incorporation of $TiO_3$ as a phtocatalytic function and by incorporation of inorganic pigment as a color function were also investigated. $TiO_2$ coating properties were controllable by adjusting pH, temperature, and the concentration of $TiOSO_4$. In XRD measurement, the crystal form of the coated $TiO_2$ was anatase. For the colorization of the capsules, inorganic pigments were more efficient than organic dyes, and various color was introduced to the capsules using inorganic pigments.