• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.5
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• pp.321-326
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• 2021

We fabricated BiAlO thin film by a solution process with a brush coating to be used as liquid crystal (LC) alignment layer. Solution-processed BiAlO was coated on the glass substrate by brush process. Prepared thin films were annealed at different temperatures of 80℃, 180℃, and 280℃. To verify whether the BiAlO film was formed properly, X-ray photoelectron spectroscopy analysis was performed on Bi and Al. Using a crystal rotation method by polarized optical microscopy, LC alignment state was evaluated. At the annealing temperature of 280℃, the uniform homogenous LC alignment was achieved. To reveal the mechanism of LC alignment by brush coating, field emission scanning electron microscope was used. Through this analysis, spin-coated and brush coated film surface were compared. It was revealed that physical anisotropy was induced by brush coating at a high annealing temperature. Particles were aligned in one direction along which brush coating was made, resulting in a physical anisotropy that affects a uniform LC alignment. Therefore, it was confirmed that brush coating combined with BiAlO thin film annealed at high temperature has a significant potential for LC alignment.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.6
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• pp.4039-4045
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• 2014

The crystallization behavior of irradiated polypropylene (PP) and the blend is an important parameter for polymer processing. Blends of PP/low density polyethylene (LDPE) with different LDPE contents were prepared by melt mixing in a twin screw extruder. The effect of the LDPE content on the irradiation effectiveness of the PP/LDPE blend with trimethylolpropane-trimetacrylate (TMPTMA) as a crosslinking co-agent was investigated in conjunction with the LDPE loading in the blend. The non-isothermal crystallization and crystal structure were measured by DSC, X-ray diffraction (XRD), and polarized optical microscopy (POM). A decrease in the melting temperature of PP was observed due to irradiation, which may be due to the PP chain scissioning effect of irradiation. The Ozawa component n represents a rod shaped, disc shaped and sphere-shaped geometry of the crystal if the value corresponds to 2, 3 and 4, respectively. Based on Ozawa analysis, the values of n were 3.8 and 2.3 for the pure PP and PP blends with 30 wt% LDPE, respectively. The fact that the crystal geometry of PP changed from spherical to disc and rod shaped was confirmed by Ozawa analysis and POM. The ${\beta}$ form XRD peak of the PP/LDPE blend at $16.1^{\circ}$ disappeared after irradiation due to the crosslinking reaction.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.1
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• pp.83-91
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• 2008

Dental caries which is one of the most common chronic disease complexly developed by the action of oral bacteria, diet, and host factor. Various prevention program enhance resistance of demineralization and reduce the acidogenecity of oral bacteria have been introduced, representative material is fluoride and chlorhexidine. The purpose of the study was to evaluate and compare effectiveness of fluoride varnish and chlorhexidine varnish in vivo. Bovine tooth specimens were implanted in the lower space maintainers and applied with fluoride varnish and chlorhexidine varnish. After seven days in oral environment, metal mesh was covered to make similar condition of plaque accumulation and induce caries. All specimens were analysed by EPMA to evaluate quantitative change of Ca, P and by polarized microscope to identify histological changes. The results were as follows : After initial artificial caries induction in the mouth, there were remarkable enamel caries lesion in the control group under polarized light microscopy. The highest amount of mineral decrease were showed in control group. No statistically significant mineral decrease were showed in fluoride varnish group, while chlorhexidine varnish group showed only significant decrease of P(P<0.05). In conclusion both fluoride varnish and chlorhexidine varnish seemed to be effective for protecting enamel surface from caries activity, although fluoride varnish has more anticariogenic effect than chlorhexidine varnish.

• Applied Chemistry for Engineering
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• v.21 no.1
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• pp.40-45
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• 2010

Entrapment of hydrophobic flavonoid luteolin into ethosome was carried out for improving its stability and making practical application in the field of drug and cosmetics. The formation of liquid crystalline phase and its thermal properties were investigated by polarized optical microscopy and DSC. The phase inversion from W/O to W/O/W was detected by conductivity change with the addition of PBS buffer solution into the ethanol-dissolved lecithin mixture. The particle size change of ethosome with constituent composition was examined, which showed that the incorporation of luteolin into lecithin up to 10% had little effect on the size of ethosome. Enhancement of stability of luteolin by entrapment into ethosome was verified through DPPH test. The stabilization efficacy of ethosome was improved further by the addition of tocopherol.

• Economic and Environmental Geology
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• v.27 no.2
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• pp.181-190
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• 1994

Petrochemical study on the micrographic granite distributed in the Wando area, the southernmost part of the Yeongdong-Kwangju depression is performed to investigate the petrogenesis and differentiation processes of the granitic magma. Polarized light microscopy for modal analyses, electron probe microanalyses of feldspars and biotite, inductively coupled plasma analyses for major and trace element contents were adopted in the study. The lithology of the study area consists of Precambrian metasediments, Mesozoic volcanic and sedimentary rocks, and micrographic granite which intrude into the former. The micrographic granite in the Wando area are distributed in the shape of a cauldron. Modal and nonnative mineral analyses of the micrographic granite fall in the area of granite and granodiorite. The chemical composition indicates that the micrographic granite is I-type and magnetite series. The micrographic granite is characterized by more than 90% of micrographic texture in volume percent. Feldspars in the micrographic granite is alkali feldspars (Or, 45~93) and plagioclases (albite to oligoclase). The biotite has a intermediate composition between phlogopite and annite solid solution. The results of the petrochemical studies indicate that the granitic magma of calc-alkaline source materials reactivated in a compressional environment at the continental margin, and then was differentiated by fractional crystallization. The micrographic granite intruded into a shallow level of the crust (5~7 km) in the late Cretaceous.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.6
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• pp.542-546
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• 1999

InP single crystal, III-V binary compound semiconductor, was grown by VGF(vertical gradient freeze) method using quartz ampoule and its electrical optical properties were investigated. Phosphorous powders were put in the bottom of quartz ampoule and Indium metal charged in conical quartz crucible what was attached at the upper side position inside the quartz ampoule. It was vacuous under the pressure of $10^5$Torr and sealed up. Indium metal was melted at $1070^{\circ}C$ and InP composition was formed by diffusion of phosphorous sublimated at $450^{\circ}C$ into Indium melt. By cooling the InP composition melt ($2^{\circ}C$~$5^{\circ}C$/hr of cooling rate) in range of $1070^{\circ}C$~$900^{\circ}C$, InP crystal was grown. The grown InP single crystals were investigated by X-ray analysis and polarized optical microscopy. Electrical properties were measured by Van der Pauw method. At the cooling method. At the cooling rate of $2^{\circ}C$/hr, growth direction of ingot was [111] and the quality of ingot was better at the upper side of ingot than the lower side. It was found that the InP crystals were n-type semiconductor and the carrier concentration, electron mobility and relative resistivity were $10^{15}$~$10^{16}/\textrm{cm}^3$ , $2\times 10^3$~$3\times 10^4{\textrm}{cm}^2$/Vsec and$2\times 10^{-1}$~$2\times 10^{-3}$/ Wcm in the range of 150K~300K, respectively.

• The Journal of the Korean dental association
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• v.56 no.1
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• pp.8-16
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• 2018

Purpose: The aim of in vitro study was to compare the diagnostic accuracy to detect non-cavitated enamel caries on smooth surface by using four kinds of the QLF devices. Materials and Methods: A total of 52 human permanent premolars and molars were used. Fluorescence images were captured by the QLF devices (Inspektor Pro, QLF-D, Qraycam, and Qraypen). Fluorescence loss of the QLF was calculated. The severity of lesions was categorized into the following 3 scores using polarized light microscopy: normal (S), enamel demineralization to outer half of enamel (D1), and inner half of the enamel up to the dentin-enamel junction (D2). The Kruskal-Wallis test was used to compare the fluorescence loss among the QLF devices. Spearman rank correlation coefficient between histological scores and fluorescence loss of the devices was calculated. The sensitivity, specificity, and area under the receiver operating curve (AUROC) were calculated to compare their diagnostic accuracies. Results: The correlation coefficients between histological scores and the fluorescence loss of the devices showed 0.77 to 0.81 (P < 0.001). All histological scores, the fluorescence loss among the devices showed no statistical difference. Among the devices, sensitivity, specificity, and AUC values of the fluorescence loss showed 0.84 to 0.94, 0.76 to 0.90, and 0.90 to 0.92, respectively. Conclusions: All QLF devices had no difference with excellent diagnostic accuracies to detect non-cavitated enamel caries on smooth surface.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.766-768
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• 2004

Rubbed films of a series of poly(p-phenylene 3,6-bis(4-(n-alkyloxy)phenyloxy)pyromellitimide)s (Cn-PMDA-PDA PIs), which are well-defined brush PIs composed of two aromatic-aliphatic bristles per repeat unit of a fully rodlike backbone, were investigated in detail using atomic force microscopy (AFM), optical retardation analysis and linearly polarized infrared (IR) spectroscopy in order to elucidate their surface morphology and molecular orientation. The liquid crystal (LC) alignment behavior and the anchoring energy of LC molecules on the rubbed films were also determined.

• Korean Journal of Plant Resources
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• v.14 no.2
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• pp.102-107
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• 2001

This study was carried out to explore for the possibility of recycling the pine wood sawdusts for the substrate for enokitake (Flammulina velutipes) cultivation. The wood species of sawdusts cultivated for enokitake mushroom were identified mostly as hard pine (Pinus spp.). Distribution of enokitake hyphae was restricted to ray parenchymas and tracheids exposed to fungi. Nevertheless, degree of cell wall degradation by enokitake was slight. Light microscopic observation showed the thinning of secondary cell wall in some tracheids. Under polarized microscopy the 1()ss of birefringence was observed only in a few latewood tracheids. All the middle lamella remained intact. The present work showed clearly that pine sawdusts used as substrate for enokitake cultivation held enough cell wall materials for mushroom cultivation. The relative resistance of softwood cell walls against enokitake fungus was also discussed.

• KOMUNHWA
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• no.66
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• pp.87-112
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• 2005

Stain removal on ivory has been, for a long time, considered an undesirable treatment in conservation field because ivory is hygroscopic and anisotropic, having different physical properties in different directions. Cyclododecane, which sublimes at room temperature, has been investigated for its use in conservation field since 1995, as a reversible temporary consolidant, sealing agent or coating, water repellent, and barrier layer. This research aims to remove stains on ivory, temporarily protecting the none-stained area or painted area from methanol, acetone or the aqueous cleaning system using cyclododecane as a hydrophobic sealing agent. This research also aims to obtain information regarding whether cyclododecane can be safely and effectively used on archaeological wet ivory. Melted cyclododecane and saturated solutions of cyclododecane in mineral spirits, and hexanes were applied to ivory samples. Application methods, working properties of cyclododecane on ivory, and effect of cyclododecane coating on moisture content of wet ivory were evaluated. The sealing layer formed by molten cyclododecane or by saturated cyclododecane solution in hexane or saturated cyclododecane solution in mineral spirits did not form a secure contact with the surface of the highly polished ivory. The sealing formed with two different layers, in which saturated cyclododecane solution in hexane was applied initially and then molten cyclododecane was applied over the first layer, was found to securely protect the painted area. When the wet samples were kept in 100% RH environments for a month, active mold growths were observed except in the samples sealed with molten cyclododecane. In conclusion, cyclododecane was an efficient hydrophobic sealing agent to protect painting area while cleaning stains on ivory. It also prevented mold growing on wet ivory and wet bone. Evenness of cyclododecane film on ivory will be determined in UV light. Analytical techniques will include visual observation, polarized light microscopy, Scanning Electron Microscope, and Gas Chromatography.