• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.29 no.2
• /
• pp.71-76
• /
• 2019

Recently, the demand of labels for product management is increasing, as the automation system becomes more common. the development of functional labels which can be used in various environments has been rapidly proceeded. In the case of a printed circuit board, barcode labels with thermal and chemical stability are generally used due to a high temperature process around $300^{\circ}C$ and chemical cleaning in the manufacturing process. However, the yellowing phenomenon of labels that can lower the resolution of printed barcode image still needs to be prevented. In this study, we prepared a composite coating layer using a silica inorganic binder and a titanium dioxide white pigment, and developed a functional labels with thermal and chemical stability. The silica inorganic binder prepared by sol-gel process was confirmed to show excellent adhesion and abrasion resistance with the polyimide film. The white coating layer could be formed on the polyimide film with mixing the silica inorganic binder and titanium dioxide white pigment. The prepared coating layer showed excellent whiteness and glossiness above $400^{\circ}C$. The excellent chemical stability of the coating layer was also confirmed by the chemical treatment with acidic (pH 1.6) and basic (pH 13.6) cleaners.

• Weed & Turfgrass Science
• /
• v.3 no.4
• /
• pp.329-335
• /
• 2014

This study was performed to study characteristics of new zoysiagarass cultivar 'Green Ever' (Plant Variety Protection Application no. 2014 - 02). 'Green Ever' was developed by selection breeding among 100 native zoysiagrasses collected in South Korea. 'Green Ever' showed specific bands (1.48 kb with OPC14 and 1.05 kb with OPD5) which were distinct from 'Anyang Joonggi' or 'Dongrae Koryogi' in RAPD analysis. 'Green Ever' was classified as Z. matrella in morphological evaluations including plant height ($6.8{\pm}0.5cm$), leaf width ($2.0{\pm}0.1mm$), height of lowest leaf ($1.9{\pm}0.1cm$) and seed length ($3.0{\pm}0.1mm$), which was similar with morphological characteristics of 'Dongrae Koryogi'. Turf quality, shoot density and chlorophyll content of 'Green Ever' were higher than them of 'Anyang Joonggi' and 'Dongrae Koryogi' under intensive management such as fairway on golf course, especially shoot densities of 'Green Ever' were excellent higher than 'Anyang Joonggi' and 'Dongrae Koryogi' during experimental periods. It could be extensively used in fairway, teeing ground of golf courses and landscape garden after further study about various environmental adaptabilities such as winter kill, wear tolerance etc.

• Journal of Adhesion and Interface
• /
• v.12 no.2
• /
• pp.47-55
• /
• 2011

UV-curable coatings have been used in various industries due to their advantages such as high mechanical property, good solvent resistance, fast curing process and low volatile organic compounds. However, a lack of flexibility of UV-cured films is a weak point for the pre-coated system of roll-to-roll process. In this study, UV-curable polycarbonate-based methacrylates were synthesized with polycarbonate diol, isophorone diisocyanate and 2-hydroxyethylmethacrylate to improve flexibility of the UC-cured films. The effects of polyol molecular weight, content of photoinitiator and monomers on the UV-curing behavior, flexibility and properties were investigated. The UV-curing behavior was measured by a photo-DSC, the pendulum hardness, tensile strength, viscoelastic properties were also evaluated.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.28 no.6
• /
• pp.256-262
• /
• 2018

A great amount of fly ash, which is a waste from a thermal power plant, has not been appropriately recycled until now. Landfill of flay ash causes environmental pollution and enormous economic costs. In this study, manufacturing of architectural ceramic tile was investigated replacing fly ash with clay raw material. The properties of porcelain tile was analyzed after manufacturing porcelain tile with mineral based glaze and fast firing process. In particular, the effect of the fly ash addition on the properties of ceramic tile was investigated by increasing the amount of limestone addition. Porcelain tile with fly ash showed excellent bending strength, water absorption, warping and abrasion resistance. However, a significant decrease in durability was observed through the autoclave test. Addition of limestone increased the water absorption, twisting and hydration expansion of the ceramic tile, but it was confirmed that the durability of the ceramic tile with fly ash was greatly improved. In conclusion, recycled architectural ceramic tiles, which can meet domestic construction standards, could be manufactured with the addition of fly ash and limestone.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.28 no.3
• /
• pp.464-470
• /
• 2001

The purpose of this study was to evaluate the tensile strength of light-cured restorative posterior resin-based composites. Five commercially available light-cured composites(Denfil : DF, P60 : PS, Unifil S : US, Z100 : ZH, Z250 : ZT) were used. Rectangular tension test specimens were fabricated in a teflon mold giving 5mm in gauge length and 2mm in thickness. Specimens were subjected to the 5,000 thermal cycles between $5^{\circ}C$ and $55^{\circ}C$ and the immersion time in each bath was 15 second per cycle. Tensile testing was carried out with Instron at a crosshead speed of 0.5mm/min and fractured surface were observed with scanning electron microscope. The obtained results were summarized as follows; 1. The tensile strength of PS was highest. PS was significantly higher than DF, US and ZH(p<0.05) but in the case of ZT was similar to PS(p>0.05). 2. The tensile strength DF was lowest. DF was significantly lower than PS, US, ZH and ZT(p<0.05). 3. The tensile strength of US and ZH were significantly lower than PS and ZT(p<0.05). but were significantly higher than DF(p<0.05). The tensile strength of US and ZH were similar(p>0.05).

• Journal of the Korean Institute of Landscape Architecture
• /
• v.38 no.1
• /
• pp.129-136
• /
• 2010

This study was initiated to investigate thatch accumulation in several turfgrasses grown under two soil systems. The 45 centimeter deep USGA system was constructed with rootzone, intermediate and drainage layers. The mono-layer system, however, was made with only a 30cm rootzone layer. Turfgrasses used in the study were comprised of 3 varieties from Korean lawngrass of Warm-Season Grass(WSG) and 3 blends and 3 mixtures from Cool-Season Grass(CSG). A total of 9 turfgrass treatments were replicated three times in RCBD in both systems. Cultural practices for the research plot followed a typical maintenance program for highly managed turf. Treatment differences for thatch accumulation were observed among the turfgrasses in both soil systems. Thatch under the USGA system was 9% greater than under the mono-layer system due to its more favorable conditions for turf growth. Higher thatch depth was found with Korean lawngrass, 34~87% in the USGA system and 16~75% in the mono-layer system when compared with CSG. Among WSG, the Joongji variety was the highest in thatch layer under both the USGA and mono-layer systems. Kentucky bluegrass(KB) was the greatest among CSG, since it is a rhizomatous-type in growth habit, resulting in faster production of organic matter over bunch-type of tall fescue and perennial ryegrass. Proper depth in the thatch layer was known to be beneficial by enhancing the resiliency and wear tolerance of the turf in athletic fields. Thus, KB was considered to be a very excellent turfgrass in terms of turf quality, environmental performance, physical properties and soccer player safety. However, disadvantages such as poor water-holding properties, more inclined to injury from environmental stresses and severe diseases and insect injury were also expected where thatch was excessively accumulated. Therefore, these results demonstrate that more frequent measures for controlling thatch such as vertical mowing, topdressing or coring should be employed for soccer fields with Korean lawngrass and KB over other turfgrasses.

• Clinical and Experimental Pediatrics
• /
• v.53 no.4
• /
• pp.488-494
• /
• 2010

Purpose : A human milk bank collects, processes, eliminates, and stores breast milk from donors and provides breast milk to those in need. The authors hereby present the experiences and the objective lessons obtained through operating a nationwide human milk bank over a period of 2 years. Methods : The characteristics of the donors and the recipients and the amounts of breast milk donated, processed, and received at the East-West Neo Medical Center Human Milk Bank were investigated from August 2007 to August 2009. Results : The donor pool consisted of 131 first-time donors and 39 repeat donors who made 341 and 127 donations, respectively. Seventy-nine percent of the donors resided in the Seoul-Kyunggi area, and 60% of the donors were in their 30s. Most information and motivation came from the Internet (66%) or television (14%). A total of 2,736 L of breast milk was collected, and 1,979 L were processed. The cumulative number of recipients was 160 preterm or full-term infants and 21 adults, each group receiving the breast milk 337 and 41 times, respectively. In total, infants received 1,663 L and adults received 179 L. Conclusion : Through the present study, the role and importance of a human milk bank in collecting, pasteurizing, and storing surplus breast milk in through sanitary, medically proven methods and providing this breast milk to recipients could be appreciated and reevaluated. The authors believe that a national support system is necessary to expand this practice to a nationwide scale.