• International Journal of Reliability and Applications
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• v.6 no.2
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• pp.79-85
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• 2005

We show how comparative mean residual life functions (MRL) can be used to give unique insights into strengths of materials data. Recall that Weibull's original reliability function was developed studying and fitting strengths for various materials. This creative comparing of MRL functions approach can be used for regular life data or any time to response data. We apply graphical MRL's to real data from tests of tensile strength of high quality engineered wood.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.05a
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• pp.335-336
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• 2018

This study discusses the development of asphalt based waterproofing sheet applied on the blind side of the concrete substrate. The inorganic coating membrane is applied on top of the waterproofing sheet surface for protection, and adhesive bond to the concrete substrate surface is secured via hydration reaction the cement. The study reveals the experimental results of the overlap section tensile strength to observe the effects of the adhesion strength of this material.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.131-134
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• 2005

Until recently tensile stresses in concrete have not been considered, since it does not affect the ultimate strength of reinforced concrete flexural members significantly. However, to verify the load-deflection relationship, the effect of tensile stresses between reinforcing bars and concrete, so-called tension stiffening effect must be taken into account. Main parameters of the tension stiffening behavior are known as concrete strength, and bond between concrete and reinforcing bars. In this study a total of twenty specimen subject to bending was tested with different concrete strength, coverage, and de-bonding length of longitudinal bars. The effects of these parameters on the flexural rigidity, crack initiation and propagation were carefully checked and analyzed.

• International Journal of Reliability and Applications
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• v.8 no.1
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• pp.111-124
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• 2007

In this paper, we apply insightful statistical reliability tools to manage and seek improvements in the strengths of Oriented Strand Board (OSB). As a part of the OSB manufacturing process, the product undergoes destructive testing at various intervals to determine compliance with customers' specifications. Workers perform these tests on sampled cross sections of the OSB panel to measure the tensile strength, also called internal bond (IB), in pounds per square inches until failure. Additional stiffness strength tests include parallel and perpendicular elasticity indices (EI), which are taken from cross sectional samples of the OSB panel in the parallel and perpendicular directions with respect to the orientation of the wood strands. We explore both graphically and statistically these "pressure-to-failures" of OSB. Also, we briefly comment on reducing sources of variability in the IB and EI of OSB.

• Fibers and Polymers
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• v.3 no.1
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• pp.38-42
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• 2002

Polypropylene filaments were spun from a mixture of PP chips of two different Melt Flow Index (MFI) (3 MFI and 35 MFI). A significant difference was observed in the melting characteristics of the resultant filaments from either of the individual components as observed from the DSC. The main difference being in the degree of melting achieved at any temperature in the initial stages of the melting range, which was found to be higher in case of the filaments spun from the b]end. These filaments were then thermally bonded using silicon oil bath and heated roller method. Subsequently the bond strength of the filaments was measured on the Instron Tensile Tester using the loop technique. The values of the world strengths obtained from the blend were compared with those made from the individual component. It was found that the bond strength of the bonds obtained from the blended filament at a given temperature was higher than that of the bonds made from the filaments of either of the individual components, which is also suggested by the DSC curves. The difference in the bond strength was found to be as high as 25% in case of the blend with 60:40 composition ratios of the 3 MFI and 35 MFI components respectively.

• Proceedings of the Korea Concrete Institute Conference
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• 1997.10a
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• pp.519-526
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• 1997

The purpose of this study is to develop the analytical model for the reinforcement bar connection in group-filled steel pipe sleeve, which consists of beam elements for the reinforcement bar and shell elements for the sleeve and the mortar and spring elements for the bond stress-slip relationship. In the reinforcement bar connection using grout-filled steel pipe sleeve, the major variables are the bond stiffness between reinforcement bar and mortar($K_1$) and between sleeve and mortar($K_2$). It is nearly difficult to predict the exact bond stiffness with the experimental results. Therefore, The linearly elastic analyses using ABAQUS, FEM package show the validity of the mathematical equations for the bond stiffness and the choice of material elements in this paper. To predict the behaviour between yield and ultimate tensile strength, the nonlinear analyses must be performed henceforth.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.2279-2286
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• 2015

Recently it has been actively studied that the use of hybrid GFRP-concrete structure with dual purpose of both a permanent forwork and main tensile reinforcement of GFRP plank. In applying general analysis and design technique to evaluate the performance of hybrid structures with cast-in-place high strength concrete and GFRP plank, it is essential that the characteristics of the bond slip model is identified. In this study a simplified bilinear bond slip model for hybrid structure with GFRP plank and cast-in-place high strength concrete is proposed. Maximum average bond stress of simple bond slip relationship that has been proposed in this study is 3.29MPa, initial slope is 35.66MPa/mm, the total slip is 0.23mm and interfacial fracture energy is 0.37kN/m.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.113-128
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• 1995

The purpose of this study was to investigate the effect of stannous fluoride on the dentin bonding with three kinds of commercially available dentin bonding systems containing different adhesive monomers. Dentin specimens with exposed labial dentin prepared from freshly extracted bovine mandibular anterior teeth were divided into experimental and control groups. The specimens of experimental groups were bonded with dentin bonding systems and composite resins including All bond 2 ㅡ& Bisfil, Scotchbond Multi-Purpose & Z100, and Denthesive II Charisma after 2 % stannous& fluorided application for S minutes and washing for 1 minute. The specimens of control groups were bonded with the same dentin bonding systems and composite resins as used in the experimental groups. After bonded specimens were stored in $37^{\circ}C$ distilled water for 24 hours, the tensile bond strength and cohesive failure rate were measured, and then the pretreated dentin surfaces and the fractured dentin surfaces were examined under scanning electron microscope. The results were as follows : Mean bond strength of stannous fluoride applied groups of All bond 2, Scotchbond MP, and Denthesive II were 2.5MPa, 1.1MPa, and 1.1MPa respectively, and those of control groups were 7.5MPa, 8.1MPa, and 4.6MPa. Bond strength values of stannous fluoride applied groups were significantly lower than those of the control groups(p<0.05). SEM findings of dentin surfaces after stannous fluoride application demonstrated an appearance of partially remained smear layer and smear plugs inspite of pretreatment with 10 % phosphoric aicd or maleic acid solution, and an appearance of smear layer covered surface under Denthesive II priming. But those of control groups commonly showed clean dentin surfaces without smear layer and smear plugs. On SEM observation of the fractured dentin-resin interface, while most of the specimens of stannous fluoride applied groups showed adhesive failure mode, those of All bond 2 and Scotchbond MP control groups showed mainly adhesive-cohesive mixed failure mode, and mainly adhesive failure mode in Denthesive II control group.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.134-141
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• 2017

Many studies have been conducted with respect to the materials to replace the cement in order to reduce the carbon dioxide emissions during the cement production. Activated hwangtoh as cement replacement material goes through calcination process of $850^{\circ}C$. PVA fibers and GFRP bars are used in order to compensate for the cracks of activated hwangtoh concrete(AHC). This paper presents an experimental study investigating the bond characteristic of GFRP bars in PVA fiber reinforced AHC under tensile loads. Experimental results showed that average bond strength factor of specimens with and without PVA fiber was 2.27~2.48 and was not significantly affected by the ratio of PVA fiber andactivated hwangtoh. In addition, as the bond length was increased, the bond strength was reduced.

• Journal of Dental Rehabilitation and Applied Science
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• v.22 no.2
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• pp.193-202
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• 2006

Objective To evaluate the influence of water storage on the mechanical properties of dental adhesives over 1 and 3 months. Materials and Methods Adhesive resin sheets were prepared by pouring either All-bond 2(AB), Clearfil SE Bond(SE) into a mold measuring $15{\times}15{\times}0.9mm$. After solvent in primer evaporation, the adhesives were light-cured and removed from the mold and divided in two pieces, trimmed to hourglass shape that were used to determine the micro-tensile strength(MTS). Another hourglass shaped metal mold measuring $2.0{\times}1.5mm$ in cross-section area was made to determine the Young's modulus(E). Adhesive specimens for Young's modulus(E) were prepared in the same method. Specimens were stored at $37^{\circ}C$ in distilled water and tested after 1 and 3 months. The data were analyzed by one-way ANOVA and Tukey's test. Results Water storage significantly decreased the micro-tensile strength(MTS) of AB and SE specimens after 1 and 3 months(P<0.05). The Young's modulus(E) were also decreased after water storage for 1 and 3 months, but statistically not significant in each group of AB and SE group respectively. Conclusions Long-term exposure of adhesive resin to water can cause reduction of mechanical properties. It may compromise resin/dentin bonds and affect longevity of restorations.