• Korean Journal of Materials Research
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• 제17권10호
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• pp.544-547
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• 2007

Human teeth were scratched by the abrasive paper, dropping in hydroxyapatite solution during 1, 2, 3, 4 months. We studied teeth surface change with SEM each months. After 1 months treatment the surface appeared the change. Because of the hydroxyapatite ion exchange mechanism. The scratched surface was recovered by the hydroxyapatite. The results of EDS showed that $Ca^{2+}$ ion and $PO_4^{3-}$ ion were removed from hydroxyapatite solution to scratched teeth surface.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• 제36권2호
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• pp.24-32
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• 2004

Toner used in xerographic printing process is hydrophobic powder with low surface energy. The toner ink film fused on paper surface can be efficiently detached from a fiber surface during pulping, but it does not fragment again into fine toner particles. Ink agglomerates that result have too large particle size to be deinked by flotation. The purpose of this study is to enhance toner agglomeration using 1-octadecanol for improving the toner removal by screening. The effect of pH, pulping temperature, and 1-octadecanol on toner agglomeration and removal by screening was investigated using image analysis methods. Results showed that the size of toner agglomerates increased substantially when pulping was carried out at high temperature under acidic condition. When toner agglomerates showed spherical shape, the particle removal efficiency of screening was improved.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 한국표면공학회 2003년도 추계학술발표회초록집
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• pp.58-58
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• 2003

Silver doped ZnO (SZO) films were prepared by rf magnetron sputtering on glass substrates with extraordinary designed ZnO target. With the doping source for target, use AgNO$_3$ powder on a various rate (0, 2, and 4 wt.%). We investigated dependence of coating parameter such as dopant content in target and substrate temperature in the SZO films. The SZO films have a preferred orientation in the (002) direction. As amounts of the Ag dopant in the target were increased, the crystallinity and the transmittance and optical band gap were decreased. And the substrate temperature were increased, the crystallinity and the transmittance were increased. But the crystallinity and the transmittance of SZO films were retrograde at 200$^{\circ}C$. Upside facts were related with composition. In addition, the Oxygen K-edge features of the SZO films were investigated by using near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Changes of optical band gap of the SZO films were explained compared with XRD, XPS and NEXAFS spectra.

• Journal of the Korean Society for Heat Treatment
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• 제36권1호
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• pp.33-39
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• 2023

In this study, the effect of mixing condition of raw material powders possessing various particle size and particle size distribution on thermite reaction efficiency was investigated. When fine raw powders are used, rather the reaction yield tends to decrease due to agglomeration. In contrast, coarse raw powders make deteriorate the contact area between raw material powders containing Al reducing agent. To ensure the optimal thermite reaction efficiency, it is required to optimize a mixture condition of raw material powders prior to thermite reaction. From the current experiment, the maximum thermite reaction efficiency is 77%, which came from Nb₂O₅ + NiO +Al mixtures with size distribution from 9.25 to 22.63 ㎛.

• Proceedings of the Korean Institute of Building Construction Conference
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• 한국건축시공학회 2023년도 가을학술발표대회논문집
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• pp.35-36
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• 2023

In this study, the hydration characteristics of conductive grout materials for each binder were investigated using XRD, and as a result of the experiment, the specimen with UFFA consumed more Ca(OH)₂ than the specimen with other binders, which is judged to have activated the pozzolanic reaction of UFFA, a high powder.

• Journal of Adhesion and Interface
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• 제17권1호
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• pp.7-14
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• 2016

Epoxy composites with concentrations of 5-70 wt% of silica particles were prepared in order to improve mechanical property and poor thermal stability. The mechanical and thermal properties were investigated and compared to the corresponding properties of neat epoxy composite. Furthermore, the effects of silane compound treatment on silica particles were observed by the experimental results of the tensile strength, glass transition temperature, and thermal stability of epoxy composite. Tensile strength of epoxy composites was measured by universal testing machine (UTM) and after that, the structure and morphology analysis of epoxy nanocomposites were analyzed by field emission scanning electron microscope (FE-SEM) and energy dispersive spectroscopy (EDS). The increased solid content of CA0030 particle improved the tensile strength of epoxy/ modified composites to give 30-50 MPa. The thermal expansion coefficients (CTE) of neat epoxy resin and epoxy/silica composites measured with a thermomechanical analyzer (TMA) showed that the incorporation of silica particles was helpful to reduce the CTE of neat epoxy resin.

• Applied Chemistry for Engineering
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• 제33권6호
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• pp.581-587
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• 2022

The leather industry generates a large amount of hazardous leather waste of various types every year. Among them, shaving scrap is difficult to recycle because it contains chromium ions. Many studies in recent years have shown that shaving scraps can be processed into various types of valuable products, such as adsorbent, filler, and poultry feed. In this study, collagen peptides were extracted from shaving scraps and structurally modified to be developed as new materials with improved physicochemical properties. First, the chromium ions contained in the shaving scraps were removed using a sodium hydroxide solution, and purified through concentration and low-temperature crystallization. The purified collagen peptide was used to prepare the powder using a spray dryer. The extracted collagen peptides were structurally modified by introducing double bonds by reacting with methacrylic anhydride (MAA), and the product was confirmed by ¹H NMR spectroscopy. Next, a copolymer was prepared by redox polymerization of the modified collagen peptide (MCP) and 2-ethylhexyl acrylate (2-EHA). The structure of the copolymer was qualitatively confirmed by FT-IR. In conclusion, this study confirmed that collagen peptides can be extracted from shaving scrap and converted into new eco-friendly materials through certain treatments.

• Journal of the Korean Society of Food Culture
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• 제20권3호
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• pp.305-314
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• 2005

This study was conducted to investigate the effects of ginseng and Schizandra chinensis on the quality characteristics of kimchi stored for 40 days at $4^{\circ}C$ after kimchi was fermented for 1 day at $25^{\circ}C$. pH and reducing sugar of GS(Kimchi added with extract powder of fine ginseng root and Schizandra chinensis juice) were the highest in the early part of storage but pH and reducing sugar of G(Kimchi added with extract powder of fine ginseng root) were the highest from 11th storage day. Acidity and $CO_2$ content of GS were the highest during storage period. The $CO_2$ content of GS was the highest significantly and the $CO_2$ content of C(Control) was the lowest significantly. When the hardness was measured, G was the hardest and there were no significant difference between C and GS. Total cells and lactic acid bacteria were increased rapidly at initial fermentation and GS was the highest of 3 samples from 6th storage day. The result of sensory evaluation showed that G was lower in sourness and higher in hardness than C and GS. Ginseng flavor had no significant differences between G and GS. And G was higher than GS in bitter taste. Consumer Acceptance test showed that consumer prefered C and GS to G. Considering all results, it can be concluded that addition of Schizandra chinensis juice to kimchi decreases the bitter taste of ginseng and increasing consumer preference.

• Conservation Science in Museum
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• 제8권
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• pp.13-24
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• 2007

The Department of Fine Art requested the conservation science team to examine the technique of painting with gold powder on the gold painted porcelains, which were made in Korea and China, among the items possessed by National Museum of Korea in order to publish it in the research paper collection of the Exchange Exhibition of Korea and China Porcelains. Among the items possessed by National Museum of Korea, such items were included as, an item of Koryo inlaid celadon (No. Gaesung 106), called the celadon with inlaid work (Korean name: Cheongjasanggam suhawonmun geumchaepyunho), which was decorated in the layer of glaze using gold power, an items of tea cup called "Temmku da wan" (No. Bongwan 10011), which was manufactured in the time of Song dynasty of Chinese history, an items of gold cup called "Siyuchohwamun hwageumwan" (No. Bongwan 2027), and an items of a porcelain called "Siyuwan" (No. Duksoo 3322). As the result of the examination, the stabilizing method of baking the decorated porcelains is similar, after they are painted with the pigment mixed with fine gold powder and the glaze solvent, but the treatment method of the colors is a little different among them. In other words, there is a big difference between them, for example, in the case of Koryo celadon, because the gold coloring was painted carefully one by one on the splendid decorations of inlaid works, while in the case of Chinese porcelains, butterflies or arabesque designs are decorated on the layer of the glaze in the porcelains of no decoration, using the stencil skill. According to the result of this examination, the part of the porcelain, whose layer of gold color was peeled off, could be restored, and as the result of the restoration, it was confirmed how beautiful and splendid the gold porcelain had been at the time of being manufactured.

• Food Science and Preservation
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• 제17권1호
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• pp.145-150
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• 2010

Ultra-fine powder (FA) extracts from persimmon were investigated as potential food materials in industrial processes because such extracts have various useful biological activities. We examined the antioxidant and anti-allergic activity of FA extracts using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and ferric reducing activity of plasma (FRAP) models, and by measuring interleukin 4 (IL-4) expression in spleen cells and in an atopy animal model. FA extracts were prepared using solvents including distilled water and 50% (v/v) acetone. The results showed that FA extracts had potent DPPH and FRAP activities, decreased IL-4 expression in spleen cells, and inhibited ear thickness and inflammation in a mouse animal model. The data indicate that a FA extract could be used as an antioxidant and/or anti-inflammation agent, and in industrial food preparation processes.