• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.38-42
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• 2016

We investigate the solution coating process of organic small molecules that are easily recrystallized in a solvent. The spin-coated films of small molecule N,N'-diphenly-N,N'-bis(1,1'-biphenyl)-4,4'-diamine (NPB) exhibit many aggregations on the surface and thus poor surface morphology. To tackle it, we have added a chain-entangled polymer poly(N-vinylcarbazole) (PVK) into the NPB solution. It is found that a small amount of PVK indeed prohibits the recrystallization of NPB in a solvent. By the addition of PVK (30 wt%), the peak-to-peak roughness of the films is reduced from 262 nm down to 2.7 nm, which is even lower than that (~5.1 nm) of the polymer film. It is also demonstrated that OLED with the PVK-mixed NPB film shows higher current and power efficiencies, compared to OLED with the NPB or PVK film. It is attributed that the addition of PVK into NPB suppresses the occurrence of leaky channels induced by the recrystallization phenomenon.

• Resources Recycling
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• v.26 no.6
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• pp.97-101
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• 2017

Metal foams have a cellular structure consisting of a solid metal containing a large volume fraction of pores. In particular, open pores which are penetrable pores are necessary for industrial applications such as in high temperature filters and as support for catalysts. In this study, Fe foam with greater than 90% porosity and 2-mm pore size was successfully fabricated using a slurry coating process and the pore properties were characterized. The Fe and $Fe_2O_3$ powder mixing ratios were controlled to produce Fe foam samples with different pore sizes and porosity. First, the slurry was prepared through the uniform mixing of powders, distilled water, and polyvinyl alcohol(PVA). The amount of slurry coated with the PU foam increased with increasing $Fe_2O_3$ mixing powder ratio, but the shrinkage and porosity of the Fe foams decreased, respectively, with increasing $Fe_2O_3$ mixing powder ratio.

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.777-782
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• 2008

Using ultrasonic-induced polymerization of pyrrole, mesoporous $TiO_2$ thin film with polypyrrole nanoparticles was prepared. Polypyrrole nanoparticles were ultrasonically synthesized in the mother solution of mesoporous $TiO_2$ before spin-coating. The polypyrrole particles were well dispersed in the solution. After spin-coating and calcinations process, the nanocomposite films have well-organized pore channels without pore-collapse, and polypyrrole nanoparticles are well dispersed in mesoporous $TiO_2$ matrix. The pore size and light absorbance of the mesoporous nanocomposite thin films were controlled by using different template materials, and by using different amount of pyrrole monomer, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.7
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• pp.652-657
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• 2009

Strength characteristics of $Si_3N_4$ composite ceramics has been studied as functions of heat-treatment temperature and additive $SiO_2$. $SiO_2$ colloidal could significantly increase the bending strength. Crack healing temperature decreased 300 K by additive $TiO_2$. Bending strength of specimen added $SiO_2$ is higher than that of non-added $SiO_2$. Moreover, bending strength of specimen with $SiO_2$ colloidal coating is much higher that of non-coated specimen. In in-situ observation, crack-healed specimen at 1,573 K shows phenomenon like a fog on the surface. By SPM, both crack-healed specimen, non-coating and coating of $SiO_2$ colloidal, at 1,273 K were healed completely but both of 1,573 K exist crack. This was made by evaporation of $SiO_2$ at high temperature. Crack-healing materials of $Si_3N_4$ composite ceramics is crystallized $Y_2Si_2O_7$, $Y_2Ti_2O_7$ and $SiO_2$. A large amount of Si and O, and little C were detected by EPMA. Si and O increase but C decreases according to heat treatment temperature. Specimens with additive $SiO_2$ were more detected Si and O than that of non-additive $SiO_2$. Specimen with $SiO_2$ colloidal coatings were much more detected O.

• Food Science and Preservation
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• v.10 no.3
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• pp.411-416
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• 2003

An effort was attempted to utilize an under-utilized protein source, rice bran protein, in coating or wrapping food material for the purpose of protection them from oxidation and bacterial infection. However, the utilization of rice bran protein as a food coating material is limited because the rice bran protein coating material itself can be spoiled by a bacterial infection. Therefore, this study was conducted to produce the economical and antibacterial rice bran protein film by utilizing rice bran and bacteriocin-producing microorganism. Bacteriocin produced by Pseudomonas putida 21025 was partially purified after 33h of shaking incubation at 30$^{\circ}C$. The amount of amino-type nitrogen did not increase in the rice bran protein film containing the bacteriocin any more after gradual increase upto the content of 0.22％ for 8 days, while that without the bacteriocin increased continuously, implying that application of the bacteriocin to the rice bran had positive effects on prolonging the shelf-life of not only film itself but also the foods wrapped by this film.

• Transactions on Electrical and Electronic Materials
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• v.5 no.1
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• pp.1-6
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• 2004

Zinc sulfide is a semiconductor with wide band gap and high refractive index and hence promising material to be used as ARC on commercial silicon solar cells. Uniform deposition of zinc sulfide (ZnS) by using chemical bath deposition (CBD) method over a large area of silicon surface is an emerging field of research because ZnS film can be used as a low cost antireflection coating (ARC). The main problem of the CBD bath process is the huge amount of precipitation that occurs during heterogeneous reaction leading to hamper the rate of deposition as well as uniformity and chemical stoichiometry of deposited film. Molar concentration of thiorea plays an important role in varying the percentage of reflectance and refractive index of as-deposited CBD ZnS film. Desirable rate of film deposition (19.6 ${\AA}$ / min), film uniformity (Std. dev. < 1.8), high value of refractive index (2.35), low reflectance (0.655) have been achieved with proper optimization of ZnS bath. Decrease in refractive index of CBD ZnS film due to high temperature treatment in air ambiance has been pointed out in this paper. Solar cells of conversion efficiency 13.8 ％ have been successfully achieved with a large area (103 mm ${\times}$ 103 mm) mono-crystalline silicon wafers by using CBD ZnS antireflection coating in this modified approach.

• Journal of the Korean institute of surface engineering
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• v.49 no.2
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• pp.202-210
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• 2016

This study was intended to investigate the effect of the amount of magnesium addition and heat treatment in the Al-Mg coating film in order to improve corrosion resistance of aluminum coating. Al-Mg alloy films were deposited on cold rolled steel by physical vapor deposition sputtering method. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of $400^{\circ}C$ for 10 min. The morphology was observed by SEM, component and phase of the deposited films were investigated by using GDLS and XRD, respectively. The corrosion behaviors of Al-Mg films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of magnesium content, the morphology of the deposited Al-Mg films changed from columnar to featureless structure and particle size was became fine. The x-ray diffraction data for deposited Al-Mg films showed only pure Al peaks. However, Al-Mg alloy peaks such as $Al_3Mg_2$ and $Al_{12}Mg_{17}$ were formed after heat treatment. All the sputtered Al-Mg films obviously showed good corrosion resistance compared with aluminum and zinc films. And corrosion resistance of Al-Mg film was increased after heat treatment.

• Food Engineering Progress
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• v.14 no.1
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• pp.27-34
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• 2010

Multilayer edible coatings was applied to lemon with beeswax-hydroxypropyl methylcellulose (BW-HPMC), soybean oil-carboxymethyl cellulose (SBO-CMC), and carnaubawax-shellac-locust bean gum (CW-SL-LBG), respectively. The multilayer was composed of two layers of the same material, but the outer layer only contained vitamins C and E as antioxidants. Coating amounts built on lemon peel were measured to be large in the order of CW-SLLBG> BW-HPMC> SBO-CMC. The coated lemons were stored at 30${^{\circ}C}$ for 12 days. CW-SL-LBG showed the least change during the storage in weight loss, rotten rate, firmness, and browning. Whereas SBO-CMC had the least change in pH, soluble solid amount, and titratable acidity. In a sensory test, CW-SL-LBG was evaluated to be the best in the attributes such as spoilage, glossiness, color, firmness, and flavor. Overall CW-SL-LBG was judged to be the best for multilayerd coating with vitamin C and E on lemon.

• Journal of Adhesion and Interface
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• v.23 no.3
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• pp.94-99
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• 2022

Ternary phased graphene/silica/EVOH nanocomposite coating materials were prepared via sol-gel process and solution blending process. From both SEM observations and XRD analysis, the exfoliated structure and dispersion state of graphene nanosheets and silica particles in the nanocomposites as well as the intercalated and exfoliated structure of the prepared graphene oxide were confirmed. The incorporation of GrO and silica at appropriate content resulted in remarkable improvement in oxygen barrier property of the ternary phased nanocompoiste-coated BOPP films, compared with that of binary(silica/EVOH) phased nanocomposite coating films, however, at excess amount of GrO and silica, very slight variation was observed due to incomplete exfoliation, dispersion of graphene tactoids, and formation of micro cracks in the silica clusters. In addition, the transparency of nanocomposite-coated film was investigated by measuring the light transmittance as a function of GrO contents, suggesting the possibility for the application of food packaging films.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.3
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• pp.363-378
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• 2005

Statement of problem. Hydroxyapatite(HA) coated titanium surfaces have not yet showed the reliable osseointegration in various conditions. Purpose. This study was aimed to investigate microstructures, chemical composition, and surface roughness of the surface coated by the hydrothermal method and to evaluate the effect of hydrothermal coating on the cell attachment, as well as cell proliferation. Material and Methods. Commercially pure(c.p.) titanium discs were used as substrates. The HA coating on c.p. titanium discs by hydrothermal method was performed in 0.12M HCl solution mixed with HA(group I) and 0.1M NaOH solution mixed with HA(group II). GroupⅠ was heated at 180 $^{\circ}C$ for 24, 48, and 72 hours. GroupⅡ was heated at 180 $^{\circ}C$ for 12, 24, and 36 hours. And the treated surfaces were evaluated by Scanning electron microscopy(SEM), Energy dispersive X-ray spectroscopy(EDS), X-ray photoelectron spectroscopy(XPS), X-ray diffraction method(XRD), Confocal laser scanning microscopy(CLSM). And SEM of fibroblast and 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT) assay were used for cellular responses of the treated surfaces. Results. The color of surface changed in both groups after the hydrothermal process. SEM images showed that coating pattern was homogeneous in group II, while inhomogeneous in group I. H72 had rosette-like precipitates. The crystalline structure grew gradually in group II, according to extending treatment period. The long needle-like crystals were prominent in N36. Calcium(Ca) and phosphorus(P) were not detected in H24 and H48 in EDS. In all specimens of group II and H72, Ca was found. Ca and P were identified in all treated groups through the analysis of XPS, but they were amorphous. Surface roughness did not increase in both groups after hydrothermal treatment. The values of surface roughness were not significantly different between groups I and II. According to the SEM images of fibroblasts, cell attachments were oriented and spread well in both treated groups, while they were not in the control group. However, no substantial amount of difference was found between groups I and II. Conclusions. In this study during the hydrothermal process procedure, coating characteristics, including the HA precipitates, crystal growth, and crystalline phases, were more satisfactory in NaOH treated group than in HCl treated group. Still, the biological responses of the modified surface by this method were not fully understood for the two tested groups did not differ significantly. Therefore, more continuous research on the relationship between the surface features and cellular responses seems to be in need.