• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.570-577
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• 1999

Intuitively, higher bond strengths should result in less leakage. However, the relationship between bond strengths and microleakage value is complex and not clearly understood. The purpose of this study was to evaluate the relationship between tensile bond strengths and microleakage values in the same restorations to understand the behavior of resin bonding to tooth structure. One-hundred and twenty enamel or dentin specimens from freshly extracted bovine mandibular incisors were used. The specimen was treated with 32% phosphoric acid for 15 seconds and rinsed for 20 seconds. the teeth were divided into four groups by means of wet bonding technique or dry bonding. One-Step$^{TM}$ adhesive were applied to the specimen. The specimens were immersed in 2% methylene blue solution for 7 days, and tensile bond strength and microleakage were measured. The results were as follows: 1. Significant negative correlation was found between bond strengths and micro leakage values. Hence, higher bond strengths seem to be associated with lower microleakage, and vice versa (r=-0 50, p<0.05). 2. The Enamel/Wet group showed significantly higher bond strength than Enamel/Dry one, and Dentin/Wet group showed higher strength than Dentin/Dry one (p<0.05). 3. Microleakage was significantly less ill wet bonding than in dry one at dentin (p<0.05), however, there was no significant difference between wet and dry bonding at enamel (p>0.05).

• Journal of the Korean Ceramic Society
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• v.51 no.5
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• pp.399-405
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• 2014

Porous alumina with different porosities, 5.2 - 47.5%, were coated with cover-glass having a thickness of $160{\mu}m$, using epoxy adhesive. We investigated the effect of the porosity of the substrate layer on the crack initiation load, and the size of cracks propagated in the coating layer. Hertzian indentations were used to evaluate the damage behavior under a constrained loading condition. Typically, two types of cracks, ring cracks and radial cracks, were observed on the surface of the glass/porous alumina structure. Indentation stress-strain curves, crack initiation loads, crack propagation sizes, and flexural strengths were investigated as a function of porosities. The results indicated that a porosity of less than 30% and a higher substrate elastic modulus were beneficial at suppressing cracks occurrence and propagation. We expect lightweight mechanical components with high strength can be successfully fabricated by coating and controlling porosities in the substrate layer.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.4
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• pp.127-135
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• 2015

Artists have been used animal glues for a long time as binding and sizing materials of paintings in many countries including Korea. Since animal glues as a binding material lose their own adhesive strength by aging, pigment particles or pigment layers are easily detached from painting surface. Restaurators prefer to use animal glues for consolidation of pigment particles or pigment layers because artists use animal glues as a binder for their painting works. It is widely known that animal glues have different characteristics such as viscosity, stability on water etc. But there are still a few requirements to consider their stabilities for the restoration of paintings. Therefore, this study was aimed to evaluate of stability and efficiency of animal glue applications. The efficiency of animal glue application was decreased with increasing the concentration of animal glue solution. This result means the simple tendency, but does not representative data for other animal glues made from same raw materials. In most cases, the surface and mechanical characteristics of animal glues are dependent on some factors, like viscosity and concentration of animal glue solution.

• Geomechanics and Engineering
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• v.8 no.4
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• pp.477-493
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• 2015

In rock drilling, the most important characteristic to clarify is the wear of the drill bits. The reason that the rock drill bits fail with time is wear. In dry sliding contact adhesive wear deteriorates the materials in contact, quickly, and is the result of shear fracture in the momentary contact joins between the surfaces. This paper aims at presenting an overview of the assessment of WC/Co cemented carbide (CC) tricone bit in rotary drilling. To study wear of these bits, two approaches have been used in this research. Firstly, the new bits were weighted before they mounted on the drill rigs and also after completion their useful life to obtain bit weight loss percentage. The characteristics of the rock types drilled by using such this bit were measured, simultaneously. Alternatively, to measure contact wear, namely, matrix wear a micrometer has been used with a resolution of 0.02 mm at different direction on the tricone bits. Equivalent quartz content (EQC), net quartz content (QC), muscovite content (Mu), coarseness index (CI) of drill cuttings and compressive strength of rocks (UCS) were obtained along with thin sections to investigate mineralogical properties in detail. The correlation between effective parameters and bit wear were obtained as result of this study. It was observed that UCS shows no significant correlation with bit wear. By increasing CI and cutting size of rocks wear of bit increases.

• International Journal of Highway Engineering
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• v.11 no.2
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• pp.133-139
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• 2009

Joints on concrete road prevent failure and crack securing the moderate space when concrete slab expands and contracts as a function of varying temperature throughout all seasons. Filling joint sealants in joints can prevent the interruption of slab movement and failure due to the infiltration of alien substances, and also can prevent crack caused by freezing and thawing and Dowel bar corrosion resulted from water - rainfall and snowfall infiltration through the inside the pavement. They lead to the improvement of the commonality of road. This paper evaluates physical strength, weatherability and deicer resistance of a two-year aged sample from joint on concrete road and its virgin sample. It was found that there are significant differences in aspects of weatherability and adhesive force between the tested sample and silicon materials.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.3
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• pp.366-374
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• 2000

FRC/ceromer system provides the clinician with a durable, flexible, and esthetic alternative to conventional porcelain fused to metal crowns. FRC is the matrix which is silica-coated and embedded in a resin matrix. The ceromer material which is a second generation indirect composite resin contains silanized, microhybrid inorganic fillers embedded in a light-curing organic matrix. FRC/ceromer restoration has a several advantages: better shock absorption, less wear of occluding teeth, translucency, color stability, bonding ability to dental hard tissues, and resiliency. It has versatility of use including inlay, onlay, single crown, and esthetic veneers. With adhesive technique, it can be used for single tooth replacement in forms of inlay adhesion bridge. In single tooth missing case, conventional PFM bridge has been used for esthetic restoration. However, this restoration has several disadvantages such as high cost, potential framework distortion during fabrication, and difficulty in repairing fractures. Inlay adhesion bridge with FRC/ceromer would be a good alternative treatment plan. This article describes a cases restored with Targis/Vectris inlay adhesion bridge. Tooth preparation guide, fabrication procedure, and cementation procedure of this system will be dealt. The strength/weakness of this restoration will be mentioned, also. If it has been used appropriately in carefully selected case, it can satisfy not only dentist's demand of sparing dental hard tissue but also patient's desire of seeking a esthetic restorations with a natural appearance.

• Composites Research
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• v.24 no.2
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• pp.1-8
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• 2011

Interfacial fracture toughness under various mixed-mode loading is measured to provide a mixed-mode fracture criterion of a composite/metal bonded joint. Experimental fracture characterization tests were carried out using a SLB (single leg bending) specimen, which controls mode ratio with the specimen thickness. The experimental result of the SLB test conforms that interfacial fracture toughness increases as the mode II component increases. The effect of loading mode on interfacial crack growth is investigated on the basis of crack path observation using microscopic image acquisition technique. The influence of interfacial roughness on adhesion strength is also discussed.

• Journal of the Society of Disaster Information
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• v.12 no.1
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• pp.54-61
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• 2016

The use of advanced composite materials in strengthening and repair of existing structures is increasing rapidly. This paper describes an effectiveness of a bonding of carbon fiber reinforced sheets to corroded steel members for the repair. Three types of surface treatment, what we call cleaning, of corroded plate are chosen as parameters. They are "without cleaning","removal of painting by brushing" and "complete removal of painting". From the experimental study, the following findings are obtained. 1) When the steel plate is subjected to tensile force, carbon fiber sheets adhered to the painted steel gives a higher strength against peeling compared to that of the plate without painting, 2) The grade of surface treatment, or cleaning of the corroded steel plate affects the strengthening effect.

• Applied Chemistry for Engineering
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• v.5 no.5
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• pp.851-856
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• 1994

Compatibility and viscoelasticity in non-solvent type pressure sensitive adhesive of styrene-isoprene-styreno(SIS) block copolymer with tackifier resin were investigated. In the isoprene phase of SIS block copolymer, it was found that it's compatibility with $C^5$ petroleum resin was good, but that with Coumarone-indents resin was not so good. The magnitudes of peel strength, tack, and holding power were as follows : $C^5$ petroleum resin>rosin ester resin>coumarone-indene resin. The tackifier resin with good compatibility in rubber phase was also effective. However, with plateau modulus value of $1{\times}10^6-3{\times}10^6dyn/cm^2$, the effect of pressure sensitive adhesives was excellent.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.965-971
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• 2001

The objective of this study is to investigate the characteristics - microstructure, hardness, adhesive strength and friction coefficient - of the coatings with aging - treatment after optimizing internal- plasma spraying parameters for Al-30wt%Si powder as a basic research to manufacture the cylinder block bore for Al engine composed of Al-30wt%Si alloy on Al alloy, The optimum internal-plasma spraying parameters of Al-30wt%Si alloy are summarized as follows: voltage: 37.5V, current: 160A, working distance: 25mm, gun traverse speed: 4.5mm/s, rotating speed: 518m/min. The primary Si particles grew aggressively with increasing heat-treating temperature. The hardness of the as-sprayed coating was about Hv=275 but this value was abruptly decreased with increasing heat-treating temperature. And average friction coefficient of the coating was below 0.08 after heat treatment for 48h at $175^{\circ}C$.