• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.613-616
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• 2008

This study is about appling non-exposure waterproofing method which combines the Cement Polymer Modified Waterproof Membrane coating and Selfadhesive Rubberized Asphalt sheet to the Roof Structure, Because there are a lot of problems in previous methods. So We had the performance tests using waterproofing method which combines two materials, and we analyzed the results. This study showed us very important results. We had bond strength test and tensile test under high, normal and low temperature, and the results were successful. And we also tested for coping with crack and movement. We found that tested materials were safe in those conditions. I think that Non-Exposure waterproofing method which combines the Cement Polymer Modified Waterproof Membrane coating and Selfadhesive Rubberized Asphalt sheet is available to concrete structure.

• Elastomers and Composites
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• v.49 no.4
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• pp.293-304
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• 2014

Rubber air spring (RAS) is a special suspension device for the industries of automobile, railroad car and other transportation. A RAS serves as a spring component with the elastic effect of compression and expansion of air in a composite rubber bag. The main component of RAS is the rubber sleeve. Rubber sleeve is the composite which is made up of combination of chloroprene rubber (CR) and nylon 6 cord, and the adhesive strength between CR and nylon 6 cord is very important. In this study, considering the effects of additives in rubber sleeve, various physical properties were tested to find the optimal combination of composition and conditions. Further, in order to select the optimum orientation of the reinforcing fibers, numerical analysis was performed using the finite elements method. After assembling all components of RAS, it was mounted on an actual vehicle, and then it was tested air leakage, fatigue life and fundamental properties.

• Polymer(Korea)
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• v.36 no.2
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• pp.196-201
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• 2012

Electrospinning is a versatile process used to prepare micro or nano sized fibers from various materials dissolved in volatile solvents. This study reports electrospun pullulan fibrous webs fabricated through electrospinning using water as a solvent. The electrospinning conditions such as pullulan (PUL) concentration and applied voltage were optimized in order to obtain smooth electrospun fibers. The concentration of PUL greatly influenced the viscosity and surface tension of PUL solution. PUL beaded electrospun fibers were obtained from PUL solutions with concentrations lower than 5 wt%, while homogenous electrospun fibers were prepared from solutions with high concentration and high viscosity. The average diameters of PUL fibers were decreased to 200 nm when the polymer concentration was kept at 10 wt% and the applied voltage was fixed at 15 kV during electrospinning. PUL electrospun fiber exhibited higher solubility, flexibility, softness and adhesive strength.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.91-95
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• 2010

A UV-enhanced atomic layer deposition (UV-ALD) process was developed to deposit $TiO_2$ thin films on Si substrates using titanium isopropoxide(TIP) and $H_2O$ as precursors with UV light. In the UV-ALD process, the surface reactions were found to be self-limiting and complementary enough to yield a uniform, conformal, pure $TiO_2$ thin film on Si substrates at room temperature. The UV light was very effective to obtain the high-quality $TiO_2$ thin films with good adhesive strength on Si substrates. The UV-ALD process was applied to produce uniform and conformal $TiO_2$ coats into deep trenches with high aspect ratio.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.25-29
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• 2009

High temperature high humidity and thermal shock reliability tests were performed for the board level COB(chip-on-board) flip chip packages using self-formulated and commercial NCPs(non-conductive pastes) to ensure the performance of NCP flip chip packages. It was considered that the more smaller fused silica filler in prototype NCPs is more favorable for high temperature high humidity reliability. The failure of NCP interconnection was affected by the expansion of epoxy due to moisture absorption rather than the fatigue due to thermal stress. It was considered that the NCP having more higher adhesive strength seems to be more favorable to increase the thermal shock reliability.

• Restorative Dentistry and Endodontics
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• v.43 no.2
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• pp.14.1-14.16
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• 2018

Objectives: The aim of this systematic review was to critically analyze previously published studies of the effects of dentin surface pretreatment with deproteinizing agents on the bonding of self-etch (SE) adhesives to dentin. Additionally, a meta-analysis was conducted to quantify the effects of the above-mentioned surface pretreatment methods on the bonding of SE adhesives to dentin. Materials and Methods: An electronic search was performed using the following databases: Scopus, PubMed and ScienceDirect. The online search was performed using the following keywords: 'dentin' or 'hypochlorous acid' or 'sodium hypochlorite' and 'self-etch adhesive.' The following categories were excluded during the assessment process: non-English articles, randomized clinical trials, case reports, animal studies, and review articles. The reviewed studies were subjected to meta-analysis to quantify the effect of the application time and concentration of sodium hypochlorite (NaOCl) and hypochlorous acid (HOCl) deproteinizing agents on bonding to dentin. Results: Only 9 laboratory studies fit the inclusion criteria of this systematic review. The results of the meta-analysis revealed that the pooled average microtensile bond strength values to dentin pre-treated with deproteinizing agents (15.71 MPa) was significantly lower than those of the non-treated control group (20.94 MPa). Conclusions: In light of the currently available scientific evidence, dentin surface pretreatment with deproteinizing agents does not enhance the bonding of SE adhesives to dentin. The HOCl deproteinizing agent exhibited minimal adverse effects on bonding to dentin in comparison with NaOCl solutions.

• Applied Microscopy
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• v.29 no.1
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• pp.67-73
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• 1999

It is practically hard to prepare good TEM specimens from powders which are embedded in epoxy materials for ion milling, because the milling rate difference between powders and epoxy is quite large. In order to overcome this problem, we tried to find methods to increase the density of powders in the embedding epoxy without loosing the adhesive strength between them. Powder density was considerably increased by employing a centrifuge for embedding, compared to the result by a conventional vacuum embedding. In addition, mixing powders of different sizes after sieving also enhanced the final density by allowing smaller particles filling in the gaps of larger particles. Ion milling of powders embedded by these methods resulted in thin specimens good enough for normal TEM works. TEM specimens from spherical, platy and fibrous powders of submicron size were successfully prepared by this centrifuging method.

• Journal of the Korean Wood Science and Technology
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• v.43 no.2
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• pp.156-167
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• 2015

The aim of this study was to determine the physical and mechanical properties of glued laminated timber (glulam) manufactured from small-diameter logs of three wood species, Acacia mangium (mangium), Maesopsis eminii (manii), and Falcataria moluccana (sengon), with densities of 533, 392, and $271kg/m^3$, respectively. Glulam measuring 5 cm by 7 cm by 160 cm in thickness, width, and length, respectively, was made with three to five lamina, or layers, and isocyanate adhesive. The glulams contained either the same wood species for all layers or a combination of mangium face and back layers with a core layer of manii or sengon. Solid wood samples of the same size for all three species were included as a basis for comparison. Physical-mechanical properties and delamination tests of glulam referred to JAS 234:2003. The results showed that the properties of same species glulam did not differ from those of solid wood, with the exception of the shear strength of glulam being lower than that of solid wood. Wood species affected glulam properties, but three- and five-layer glulams were not different except for the modulus of elasticity. All glulams were resistant to delamination by immersion in both cold and boiling water. The glulams that successfully met the JAS standard were three- and five-layer mangium, five-layer manii, and five-layer mangium-manii glulams.

• Elastomers and Composites
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• v.40 no.1
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• pp.59-65
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• 2005

Zinc methacrylate(ZMA) was incorporated into ethylene-propylene diene rubber(EPDM) by direct mixing of the metal salt with the rubber or was in-situ prepared in the rubber matrix through neutralization reaction of zinc oxide(ZnO) and methacrylic acid(MAA). Tensile and tear tests showed that ZMA had a great reinforcing effect for the EPDM. It was also found that ZMA reinforced EPDM vulcanizates can retain their mechanical properties under thermo-oxidative aging. Moreover the incorporation of ZMA induces a substantial improvement in the adhesive strength of the EPDM onto aluminum substrate. The reinforcing effect and an enhancement in adhesion was greatly manifested when the ZMA is in-situ formed with an excess amount of ZnO. The extraordinary improvement in the properties is supposed to be related with the formation of ionic crosslink as well as the degree of dispersion or ZMA domain in the rubber matrix.

• Elastomers and Composites
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• v.35 no.3
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• pp.205-214
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• 2000

The polyurethane resin was prepared by the reaction of tolylenediisocyanate(TDI) and polypropyleneglycol(PPG). Physical properties of the resin were investigated experimentally. Charging catalyst before TDI-dropping induced the rapid increase of viscosity. On the other hand, charging catalyst after TDI-dropping resulted in mild stability without immoderate generation of heat on reaction. The use of phosphoric acid as catalyst led to low viscosity by restraining side-reaction such as forming of branch-chain, buret reaction and allopanate reaction, but it showed low cross-link density and slow drying. The curing speed was more influenced by structures of molecules rather than NCO/OH ratio. Including PPG 400 over 30 wt % showed excellent adhesive strength due to increase of crosslink density.