• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.911-919
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• 1994

As the study for preparation of single-layer anti-reflective coating on glass, the conditions of synthesis of sol for coating and of reproducible coating procedure were investigated. In case of water-based sol, coating was impossible because of poor wettability of sol. The Substitution of solvent with ethanol improved the wettability of sol on the glass surface, and optimum amount of ethanol for substitution was 70 vol%. Maximum specific surface area and total pore volume of water-based sol were 268.7$m^2$/g and 0.315 cc/g, but after substitution, those values increased to 404.1 $m^2$/g and 0.376 cc/g, respectively. The upper limit withdrawl speed of coating in order to get clean coated films without aggregations or stains was 7 cm/min. In case of addition of 0.1 mol HNO3 and substitution with 70 vol% ethanol and heat-treatment at 40$0^{\circ}C$ for 1 hour, thin film with thickness of 94 nm was obtained at withdrawl speed of 4 cm/min. The thickness of thin film was independent of drying time.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.210-210
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• 2012

Gas barrier coating from dense thin film deposition has been one of the important applications such as food-packaging and organic display. Especially for food-packaging, plastic container has been widely used due to its low price and high through-put in mass production. However, the plastic container with low surface energy like polypropylene (PP) has been limited to apply gas barrier coating. That is because a gas barrier coating could not adhere to PP due to its too low surface energy and high porosity of PP. In this research, we applied carbon coating consisting of Si and O as an interlayer between silicon oxide (SiOx) and PP. A carbon layer was found to provide better adhesion, which was experimentally proved by oxygen transmission rate (OTR) and SEM images. However, we also found that there is a limitation in the maximum thickness of a carbon layer and SiOx film due to their high stress level. For this conflict, we obtain the optimal thickness of a carbon layer and SiOx film showing optimal gas barrier property.

• Korean Journal of Materials Research
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• v.12 no.3
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• pp.211-214
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• 2002

Properties of 52/48 PZT films with various thicknesses for piezoelectric micro-electro mechanical systems (MEMS) devices fabricated by multi-coating method on $Pt(3500{\AA})/Ti(400{\AA})/SiO_2(3000{\AA})/Si$(525$\mu\textrm{m}$) substrates were investigated. PZT films were deposited by spin-coating process at 3500 rpm for 30 sec, followed by pyrolysis at 45$0^{\circ}C$ for 10 min producing the thickness of about 120nm. These processes were repeated 4, 8, 12, 16 and 20 times in order to have various thicknesses, respectively. Finally, they were crystallized at $650^{\circ}C$ for 30 min. All thick PZT films showed dense and homogeneous surface microstructures. Thick PZT films showed crystalline structures of random orientations with increasing thickness. Dielectric constants of thick PZT films were increased with increasing film thickness and reached 800 at 100kHz for 2.3$\mu\textrm{m}$ thick PZT film. $P_r\; and\; E_c$ of 2.3$\mu\textrm{m}$ thick PZT films were about 20$\mu$C/$\textrm{cm}^2$ and 63kV/cm. Depth profile analysis by Auger Electron Spectroscopy (AES) of 4800 $\AA$ thick PZT film showed the formation of the perovskite phase on Pt layer by Pb diffusion behavior. It was considered that Pb-Pt intermediate layer promoted PZT (111) columnar structures.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.15 no.2
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• pp.118-124
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• 2016

In this study, experiments are conducted to improve spray coating uniformity by using second and third electrodes based on the electrospray atomization mechanism. The uniformity of fabricated thin films can be improved by adjusting the design of the second electrode. The implementation of the second electrode with an elongated hole and a bending angle of $90^{\circ}$ results in highly uniform films. In addition, induced area to substrate is increased by lowering the applied voltage using the third electrode with a round rod shape. A linear correlation between applied voltage and induced area is confirmed. Thin film thickness and surface roughness are measured after the fabrication of thin films through the electrospray process. It is confirmed that a thin film is formed having an average thickness of 273.44 nm, a thickness uniformity of less than 10%, and a surface roughness of 3 nm.

• Electrical & Electronic Materials
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• v.9 no.1
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• pp.59-66
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• 1996

Polyimides containing cyclobutane ring in main chain is known to be thermally stable and able to be developed in organic solvents after photolysis with 254 nm UV light. This type of polyimides can be used as promising positive photoresist in VLSI fabrication process. In the current VLSI process, photoresist films are formed by spin coating. The film thickness is more than several hundred nano meters. It seems that there is room for improvement of film coating process by introducing Langmuir Blodgett technique. Thereby ultra thin film photoresist can be formed, and higher density of integration in VLSI be achieved. In the present work, depositing procedure of LB films of this polyimide was investigated. LB film thickness was measured by ellipsometry to evaluate deposited film status. Chemical imidization procedure was studied to avoid several problems in thermal imidization. The pattern of submicron dimension has successfully formed on LB film of 8nm thick, which found showing good contrast.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.6
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• pp.637-645
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• 2008

It is very hard to control the quality of coating work in shipbuilding process, because it is highly affected by several parameters such as space between object and nozzle tip, spray velocity, pressure, tip size, etc.. Even so a coating work in shipbuilding is done by workers' experience and skill as yet. It causes not only an excessive use of paints but also a decrease of productivity. In order to solve this problem, we developed a formula that predicts the film thickness and determined the proper coating pattern. Also we had done a series of experiments to verify the results of this study.

• Journal of the Korean Ceramic Society
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• v.44 no.12
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• pp.733-739
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• 2007

NiO-YSZ anode-supported single cell was prepared by spin-coating YSZ and LSM slurries as electrolyte and cathode, respectively. Dense YSZ electrolyte film was successfully prepared on the porous NiO-YSZ anode substrate by tuning pre-sintering temperature of NiO-YSZ and co-firing temperature. The thickness of YSZ film was controlled by the solid content of slurry and coating cycles. The experimental conditions affecting on the thickness of YSZ film was discussed. Single cells with the active electrode area ${\sim}0.8\;cm^2$ were prepared by spin-coating the cathode layers of LSM-YSZ mixture and LSM consequently as well. The effects of the pre-sintering temperature and thus the microstructure of NiO-YSZ substrate on the current-voltage characteristics of co-fired cell were investigated.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5172-5177
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• 2011

This paper presents a reflection coating design scheme in the thin-film silicon solar cell. The antireflection(high reflection) coating skill is needed in the front(back) panel of the thin-film solar cell to improve an efficiency of light absorbing. In the single structure a reflectivity is changed according to the thickness of coating for antireflection scheme and its minimum value can be obtained by controlling thickness of coating. In the symmetric multi layer structure low reflectivity can be obtained in the wide wavelength range. And we also find that high reflectivity can be obtained through multi layer structure, which has alternate layers of high and low material, for high reflection scheme in the back panel.

• KCI Concrete Journal
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• v.13 no.2
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• pp.42-48
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• 2001

The bend resistance of coated reinforcing bar is greatly influenced by both the adhesion strength between bar and coating materials, and the followed transformation of coating material as bars bend. Especially, tearing state or partial microscopic cracks are predicted on the inside and outside of bending angle, because tensile strength and elongation of polymer film are very different according to types of polymer dispersions in bar coating, and these damaged parts are rapidly corroded by penetration of corrosive factors. In this study, polymer cement slurry coated reinforcing bars with various polymer dispersions are prepared by following combined conditions, polymer-cement ratio of 50% and 100%, coating thickness of 250$\mu$m and 450$\mu$m, coating number, curing age of 3, 7, 14 and 28days. Then the specimens are tested for working life and bend resistance at bending angles $90^{\circ}$, $135^{\circ}$and $180^{\circ}$ to observe the microscopic damage effect as the bars bend. Also, epoxy-coated reinforcing bars for control experiment were used with 250$\mu$m of coating thickness. The tensile strength for polymer films is performed. From the test results, the working life of the polymer cement slurry is within 90 seconds. Among four types of polymer dispersion, polymer cement slurry coated reinforcing bar using St/BA-1 emulsion has the excellent bend resistance, which is remarkably improved than that of epoxy-coated reinforcing bar. And the bend resistance is more related to elongation than tensile strength of polymer film. Polymer cement slurry with a polymer-cement ratio of 100%, a coating thickness of $450\mu$m and one coating using St/BA emulsion is selected as a most suitable coating material for coated reinforcing bar.

• Korean Journal of Materials Research
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• v.15 no.5
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• pp.285-292
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• 2005

Anti-reflection film was coated by using spherical silica nano colloids. Silica colloid sol was reserved between two inclined slide glasses by capillary force, and particles were convectively stacked to form a film onto the substrate as the water evaporates. As the sliding speed increased, the thickness of the film decreased and the wavelength at the maximum transmittance decreased. The microstructure observed by SEM showed that silica particles were nearly close packed, which enabled the calculation of the effective refractive index of the film. The film thickness was measured by proffer and calculated from the wavelength of maximum transmittance and the effective refractive index. The effective refractive index of the film could be controlled by a subtle controlling of the coating speed and by mixing two different sized silica particles. When the 100 nm and 50 m particles were mixed at 4:1-5:1 volume ratio, the maximum transmittance of $95.2\%$ for one-sided coating was obtained. This is the one that has increased by $3.8\%$ compared to bare glass substrate, and shows that $99.0\%$ of transmittance or $1.0\%$ of reflectance can be achieved by the simple process if both sides of the substrate are coated.