• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1448-1449
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• 2006

Pb(Zr,Ti)$O_3$ is one of the most attractive ferroelectric materials for realizing the FeRAM due to its higher remanant polarization and the ability to withstand higher coercive fields. Generally, the ferroelectric materials were patterned by a plasma etching process for high-density FeRAM. The applicable possibility of CMP process to pattern Pb(Zr,Ti)$O_3$ instead of plasma etching process was investigated in our previous study for improvement of an angled sidewall which prevents the densification of ferroelectric memory and is apt to receive the plasma damage. Our previous study showed that good removal rate with the excellent surface roughness compared to plasma etching process were obtained by CMP process for the patterning of Pb(Zr,Ti)$O_3$. The suitable selectivity to TEOS without any damage to the structural property of Pb(Zr,Ti)$O_3$ was also guaranteed. In this study, the removal mechanism of $Pb_{1.1}(Zr_{0.52}Ti_{0.48})O_3$ coated by sol-gel method was investigated. Surface analysis of polished specimens at the best and worst conditions was carried out by XPS.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1363-1364
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• 2007

The composites such as Sn-CNTs, $SnSb_{0.5}$-CNTs and $CoSb_3$-CNTs have attracted much attention in the past years owing to their good overall properties. In these samples, intermetallic compounds show high specific capacities. Recently, interest in metal oxides such as $Al_{2}O_{3}$, MgO and $TiO_2$ has been largely stimulated by the realization that they can improve the cycling stability of the Li-ion battery electrodes. The reversible capacity of the $TiO_2$/CNTs composite reaches 168 mAh $g^{-1}$ at the first cycle and remains almost constant during long-term cycling. In this study, a nanocomposite of $TiO_2$/CNTs was prepared by sol-gel method and its electrochemical properties as anode materials for Li-ion batteries were studied by galvanostatic cycling, cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS).

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.348-349
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• 2006

$LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ cathode material was synthesized by a mixed hydroxide methode. The surface of the $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ was coated with a carbon by using a sol-gel method to improve further its electrochemical properties. Electrochemical studies were performed by assembling 2032 coin cells with lithium metal as an anode. OSC (differential scanning calorimetry) data showed that exothermic reactions of charged to 4.3V vs. Li was suppressed in the carbon-coated materials. The carbon-coated $LiNi_{1/3}Mn_{1/3}Co_{1/3}O_2$ showed the improved rate capability and thermal stability.

• Polymer(Korea)
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• v.28 no.5
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• pp.391-396
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• 2004

In order to overcome drawbacks in the conventional preparation of epoxy/silica nanocomposites, such as formation of micro voids and dimensional instability caused by evolution of volatile by-products during curing reaction, a novel preparation method using Si-N precursor has been proposed. When prepared through in-situ reaction of epoxy curing reaction with sol-gel reaction of Si-N precursor, methyltripiperidinylsilane (MTPS) which does not produce by-products during reaction, epoxy/silica nanocomposites of extremely even dispersion of inorganic phase could be successfully prepared, resulting in high enhancement of mechanical and thermal properties as well as outstanding transparency.

• Food Science and Biotechnology
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• v.17 no.6
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• pp.1345-1348
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• 2008

Titanium dioxide ($TiO_2$) shows antibacterial effects when exposed to near ultra violet (UV) light. In this study, $TiO_2$ photocatalytic continuous reactor was designed and applied to food-borne pathogens such as Vibrio parahaemolyticus ATCC 17802, Salmonella choleraesuis ATCC 14028, and Listeria monocytogenes ATCC 15313. $TiO_2$ films were prepared by conventional sol-gel dip-coating method using titanium tetra iso-propoxide (TTIP). The antibacterial activity of photocatalytic reactor with various flow rates and UV-A illumination time showed effective bactericidal activity. As the UV-A illumination time increased, survival rates of those bacteria decreased. After 60 min of UV-A illumination, the survival rates of V. parahaemolyticus and S. choleraesuis were less than 0.1%. However, that of L. monocytogenes was about 5% at that time point. These results present an effective way to exclude pathogenic bacteria from aqueous foods.

• Preventive Nutrition and Food Science
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• v.9 no.3
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• pp.236-239
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• 2004

Microbial contamination of ready-to-eat ingredients for Kimbab manufacturing and the effect of irradiation to reduce the microbial contamination of the products were investigated. Among 9 food items tested, there were no viable cells in the ham, seasoned and cooked beef, imitation crab leg, fried egg, and seasoned burdoc. Cucumber, surimi gel, and seasoned and blanched spinach were counted at 5.07$\pm$0.97, 3.50$\pm$0.14, and 5.41$\pm$0.51 log CFU/g, respectively. Irradiation at 1 kGy reduced the number of microorganism in these ready-to-eat foods to an undetectable level. However, the dried laver showed an 8.83$\pm$0.10 log CFU/g and an irradiation at 3 kGy reduced the level to only 7.14$\pm$0.23. Sensory evaluation of the irradiated Kimbab prepared from these food materials indicated that the measure of the control of the sensorial quality should be provided before applying an irradiation to the prepared Kimbab.

• Macromolecular Research
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• v.17 no.11
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• pp.907-911
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• 2009

To improve the moisture stability of the $CaS:Eu^{2+}$ red phosphor, surface coatings with silica nanoparticles were performed using five different methods, i.e., $P_1$, $P_2$, $P_3$, $P_4$, and $P_5$. The phosphors were coated with silica nanoparticles using a dip coating method ($P_1$) and sol-gel method ($P_2$). The phosphors were coated using a solution containing silica nanoparticles and poly(1-vinyl-2-pyrrolidone), PVP, $(P_3$). The phosphors were also coated with silica nanoparticles by reacting with the 1-vinyl-2-pyrrolidone (VP) monomer ($P_4$) or by reacting with mixtures containing VP and tetraethylorthosilicate ($P_5$). A decrease in the photoluminescence (PL) intensity was observed regardless of the coating methods. However, the moisture stability of the phosphors was enhanced by the coating when aged in a temperature-controlled humidity chamber. Among these methods, the $P_4$ (or $P_5$) method exhibited the greatest increase in moisture stability of the phosphors. The coated phosphors showed a relatively constant intensity with aging time, whereas the uncoated phosphor showed a decrease.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.119-122
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• 2018

Various ZnO/Ag/ZnO multilayers were fabricated and their optical properties were investigated. Top and bottom ZnO layers were formed by sol-gel method and mid-metal layers were deposited by spin coating. To find suitable deposition condition of Ag, we measure thickness and sheet resistance of Ag monolayer. After the optimization of Ag monolayer, we fabricate ZnO/Ag/ZnO multilayers. Transmittance of ZnO/Ag/ZnO multilayers increased to 63%. In near IR region, transmittance of ZnO/Ag/ZnO multilayers decreased to 35% when the concentration of Ag solution was 2.5wt%.

• Journal of Ceramic Processing Research
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• v.20 no.2
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• pp.182-186
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• 2019

0.7 mol% Er-TiO2 nanotubes were prepared using a sol-gel derived electrospinning and subsequent calcination at intervals of 50 ℃ from 500 ℃ to 650 ℃ to investigate the effect of calcination temperature on the crystal structure and the photocatalytic activity of methylene blue (MB). X-ray diffraction (XRD) results indicated that Er-TiO2 nanotubes calcined at 500 ℃ were composed of anatase only. However, mixed phases of anatase (51%, 55%, 96%) and rutile (49%, 45%, 4%) were observed for the nanotubes calcined at 550 ℃, 600 ℃ and 650 ℃, respectively. As the calcination temperature rose from 500 ℃ to 600 ℃, the Barrette-Emmett-Teller (BET) surface area and degradation kinetic constant increased from 97.77 ㎡/g to 117.62 ㎡/g and from 1.2 × 10-2min-1 to 1.6 × 10-2 min-1, respectively. The Er-TiO2 nanotubes calcined at 600 ℃ exhibited enhanced MB degradation (87%) compared to that of Er-TiO2 nanofibers (37%) due to the synergic combinations of tailored mixed crystals and larger BET area.

• Korean Journal of Materials Research
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• v.32 no.5
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• pp.249-257
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• 2022

Transparent thin films of pure and nickel-doped ZrO₂ are grown successfully by sol-gel dip-coating technique. The structural and optical properties according to the different annealing temperatures (300 ℃, 400 ℃ and 500 ℃) are investigated. Analysis of crystallographic properties through X-ray diffraction pattern reveals an increase in crystallite size due to increase in crystallinity with temperature. All fabricated thin films are highly-oriented along (101) planes, which enhances the increase in nickel doping. Scanning electron microscopy and energy dispersive spectroscopy are employed to confirm the homogeneity in surface morphology as well as the doping configuration of films. The extinction coefficient is found to be on the order of 10^-2, showing the surface smoothness of deposited thin films. UV-visible spectroscopy reveals a decrease in the optical band gap with the increase in annealing temperature due to the increase in crystallite size. The variation in Urbach energy and defect density with doping and the change in annealing temperature are also studied.