• Journal of the Korean Society for Railway
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• v.19 no.2
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• pp.224-233
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• 2016

Embedded Railway Systems (ERS) will be adapted for wireless trams and will be constructed along city roadways. An asphalt layer should be overlaid on top of the concrete slab used as the trackbed structure in order to ensure smoothness and surface levels equal to those of existing road pavement in downtown city areas. However, the characteristics of an asphalt layer when used as overlay pavement for an ERS are complicated and the behavior of this material is not yet well defined and understood. Therefore, in this study, laboratory shear and tensile bond strength tests were conducted to investigate the bonding behavior of an asphalt layer in a multilayered trackbed section of an ERS. For the laboratory tests, a waterproof coating material was selected as a bonding material between the asphalt overlay and a concrete specimen. Valuable design parameters could be obtained based on the tensile and shear bond strength test results, providing information about the serviceability and durability of the overlaid pavements to be constructed alongside the ERS for wireless trams. In addition, a deformation analysis to assess the tensile strain generated due to truck axle loads at the interface between the asphalt layer and the concrete slab was conducted to verify the stability and performance of the asphalt layer.

• The Journal of Korean Academy of Prosthodontics
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• v.30 no.1
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• pp.55-64
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• 1992

This study investigated the effect of porcelain primer on bonding of coomposite resin to porcelain surface. In order to test the bond strength between porcelain and composite resin, porcelain cylinders were embedded in acrylic resin, and polished with 240grit silicone caqrbide paper. The specimens were divided into twelve groups. All specimens were treated with three porcelain primers and bonded with five composite resins. All test groups were stored in $37^{\circ}C$ distilled water for 48hours. Shear bond strengths were measured with Instron(Model 4201) at a cross-head speed of 1mm/min. The obtained results were as follows : 1. Scotchprime/Silux II group and BISCO Porcelain Primer/Bisfill group showed significant higher bond strengths than Clearfil Porcelain Primer/photo Clearfil Bright group(p<0.05). And there was no significant differences in bond strengths between Scotchprime/Silux II group and BISCO Porcelain Primer/Bisfill group(p>0.05). 2. When composite resins were used with Scotchprime, the bond strengths were decresed Silux II$(16.68{\pm}3.35MPa)$, Bisfil$(16.23{\pm}4.54MPa)$, Poly-Fill$(14.74{\pm}4.08MPa)$, Photo Clearfil Bright$(13.75{\pm}2.89MPa)$ and Pekalux$(14.74{\pm}4.08MPa)$ in order, but there was no statistical significance(p>0.05). 3. When composite resins were used with BISCO Porcelain Primer, the bond strength were decreased Bisfil$(16.17{\pm}1.60MPa)$, Silux II$(12.13{\pm}2.37MPa)$, Poly-Fill$(10.78{\pm}1.99MPa)$, Photo Cleafil Bright $(9.91{\pm}4.59MPa)$ and Pekalux$(7.36{\pm}2.16MPa)$ in order, but there was no statistical significance(p>0.05). 4. Silux II, Photo Clearfil Bright and Poly-Fill used with Scotchprime showed significant higher bond strengths than BISCO Porcelain Primer(p>0.05).

• The korean journal of orthodontics
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• v.42 no.1
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• pp.32-38
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• 2012

Objective: The aim of this study was to compare the effects of different enamel conditioning techniques for bracket bonding. Methods: Ninety-one human premolars were randomly divided in six groups of 15 specimens each. The enamel surfaces of the teeth were etched with 35% orthophosphoric acid in Group 1, with a self-etching primer in Group 2, sandblasted in Group 3, sandblasted and etched with 35% orthophosphoric acid in Group 4, conditioned by Er:YAG laser in Group 5 and conditioned by Er:YAG laser and etched with 35% phosphoric acid gel respectively in Group 6. After enamel conditioning procedures, brackets were bonded and shear bonding test was performed. After debonding, adhesive remnant index scores were calculated for all groups. One tooth from each group were inspected by scanning electron microscope for evaluating the enamel surface characteristics. Results: The laser and acid etched group showed the highest mean shear bond strength (SBS) value ($13.61{\pm}1.14$ MPa) while sandblasted group yielded the lowest value ($3.12{\pm}0.61$ MPa). Conclusions: Although the SBS values were higher, the teeth in laser conditioned groups were highly damaged. Therefore, acid etching and self-etching techniques were found to be safer for orthodontic bracket bonding. Sandblasting method was found to generate inadequate bonding strength.

• The Journal of Advanced Prosthodontics
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• v.13 no.5
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• pp.292-303
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• 2021

PURPOSE. The aim of this in vitro study was to evaluate the effect of silane and universal adhesive applications on the micro-shear bond strength (µSBS) of different resin-matrix ceramics (RMCs). MATERIALS AND METHODS. A total of 120 slides (14 × 12 × 1 mm) were produced from 5 different RMC materials (GC Cerasmart [GC]; Brilliant Crios [BC]; Grandio blocs [GB]; Katana Avencia [KA]; and KZR-CAD HR 2 [KZR]) and sandblasted using 50 ㎛ Al₂O₃ particles. Each RMC material was divided into six groups according to the surface conditioning (SC) method as follows: control (G1), silane primer (G2), silane-free universal adhesive (G3), silane-containing universal adhesive (G4), silane primer and silane-free universal adhesive (G5), and silane primer and silane-containing universal adhesive (G6). Three cylindric specimens made from resin cement (Bifix QM) were polymerized over the treated surface of each slide (n = 12). After thermal cycling (10000 cycles, 5 - 55℃), µSBS test was performed and failure types were evaluated using a stereomicroscope. Data were analyzed using 2-way ANOVA and Tukey tests (α = .05). RESULTS. µSBS values of specimens were significantly affected by the RMC type and SC protocols (P < .001) except the interaction (P = .119). Except for G2, all SC protocols showed a significant increase in µSBS values (P < .05). For all RMCs, the highest µSBS values were obtained in G4 and G6 groups. CONCLUSION. Only silane application did not affect the µSBS values regardless of the RMC type. Moreover, the application of a separate silane in addition to the universal adhesives did not improve the µSBS values. Silane-containing universal adhesive was found to be the best conditioning method for RMCs.

• Smart Structures and Systems
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• v.29 no.3
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• pp.445-455
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• 2022

Steel anchor bolts are installed in concrete using a variety of methods. One of the most common methods of anchor bolt installation is using epoxy resin as an infill material injected into the drilled hole to act as a bonding material between the steel bolt and the surrounding concrete. Typical design standards assume uniform stress distribution along the length of the anchor bolt accompanied with single crack leading to pull-out failure. Experimental evidence has shown that the steel anchor bolts fail owing to the multiple failure patterns, hence these design assumptions are not realistic. In this regard, the presented research work details the analytical model that takes into consideration multiple micro cracks in the infill material induced via impact loading. The impact loading from the Schmidt hammer is used to evaluate the bond condition bond condition of anchor bolt and the epoxy material. The added advantage of the presented analytical model is that it is able to take into account the various type of end conditions of the anchor bolts such as bent or U-shaped anchors. Through sensitivity analysis the optimum stiffness and shear strength properties of the epoxy infill material is achieved, which have shown to achieve lower displacement coupled with reduced damage to the surrounding concrete. The accuracy of the presented model is confirmed by comparing the simulated deformational responses with the experimental evidence. From the comparison it was found that the model was successful in simulating the experimental results. The proposed model can be adopted by professionals interested in predicting and controlling the deformational response of anchor bolts.

• Journal of Dental Rehabilitation and Applied Science
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• v.33 no.2
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• pp.71-79
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• 2017

Purpose: Ni-Cr alloy does not contain Beryllium, causing the metal compound to form oxides in the furnace but by using Titanium as a chemical catalyst the forming of the oxides can be controlled, and by controlling the impurities formed on the metal surface, the possibility of the Ni-Cr alloy bond strength being increased can be analysed. Materials and Methods: Titanium was used as a chemical catalyst in the porcelain for the oxidation of beryllium-free metal (Ni-Cr) alloy. The T1 group, which does not use Titanium power as a chemical catalyst is a reference model for comparison. The T2 group and T3 group used 10 g and 20 g of Titanium power, respectively. They are fabricated to observe the shear bond strength and surface properties. There was no significance when One-way ANOVA analysis/Tukey Honestly Significant Difference Test was conducted for statistical analysis among groups (P > 0.05). Results: Results of measuring the three-point flexural bond strength of the Ni-Cr alloy and thickness of the oxide film. Experiment T3 using 20 g Titanium chemical catalyst: $39.22{\pm}3.41MPa$ and $6.66{\mu}m$, having the highest bond strength and thinness of oxide film. Experiment T2 using 10 g Titanium chemical catalyst: $34.65{\pm}1.39MPa$ and $13.22{\mu}m$. Experiment T1 using no Titanium chemical catalyst: $32.37{\pm}1.91MPa$ and $22.22{\mu}m$. Conclusion: The T2 and T3 experiments using Titanium chemical catalyst showed higher bond strength for the Ni-Cr alloy and lower thickness of oxide film than experiment T1, and the titanium catalyst being able to increase bond strength was observed.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.11-30
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• 2000

Structural properties of reinforced concrete, such as bond and shear strength, that depend on the tensile properties of concrete are much lower for high-strength concrete than would be expected based on relationships developed for normal-strength concretes. To determine the reason for this behavior, studies at the University of Kansas have addressed the effects of aggregate type, water-cementitious material ratio, and age on the mechanical and fracture properties of normal and high-strength concretes. The relationships between compressive strength, flexural strength, and fracture properties were studied. At the time of test, concrete ranged in age from 5 to 180 days. Water-cementitious material ratios ranged from 0.24 to 0.50, producing compressive strengths between 20 MPa(2, 920 psi) and 99 MPa(14, 320psi). Mixes contained either basalt or crushed limestone aggregate, with maximum sizes of 12mm(1/2in). or 19mm(3/4in). The tests demonstrate that the higher quality basalt coarse aggregate provides higher strengths in compression than limestone only for the high-strength concrete, but measurably higher strengths in flexure, and significantly higher fracture energies than the limestone coarse aggregate at all water-cementitious material ratios and ages. Compressive strength, water-cementitious material ratio, and age have no apparent relationship with fracture energy, which is principally governed by coarse aggregate properties. The peak bending stress in the fracture test is linearly related to flexural strength. Overall, as concrete strength increases, the amount of energy stored in the material at the peak tensile load increases, but the ability of the material to dissipate energy remains nearly constant. This suggests that, as higher strength cementitious materials are placed in service, the probability of nonductile failures will measurably increase. Both research and educational effort will be needed to develop strategies to limit the probability of brittle failures and inform the design community of the nature of the problems associated with high-strength concrete.

• The korean journal of orthodontics
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• v.26 no.2 s.55
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• pp.175-186
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• 1996

The purpose of this study was to examine the effects of mechanical and thermal fatigue on the shear bond strength(SBS) of stainless steel mesh brackets bonded to human premolar teeth with 3 no-mix adhesives. The stainless steel mesh bracket was Ormesh(Ormco, .022 slot) and three types of no-mix adhesives were Ortho-one(Bisco), $Monolok^2$(RMO), $System\;1^+$(Ormco). The $10^6$ loadcycles of $17.4{\times}10^2sin2{\pi}ftlg{\cdot}cm$ and the 1,000 thermocycles of 15 second dwell time in each bath of $5^{\circ}C\;and\;55^{\circ}C$ were acturated as mechanical and thermal fatigue stress, and SBS were measured after each fatigue test. The fracture sites were analyzed by stereoscope and scanning electron microscope. The results obtained were summarized as follows; 1. Before thermocycles, $Monolok^2$ showed the highest Knoop hardness number(KHN, $64.03kg/mm^2$) and $System\;1^+$ showed the lowest value($31.60kg/mm^2$). After thermocycling, $Monolok^2$ also showed the highest KHN($38.03kg/mm^2$) and $system\;1^+$ showed the minimum($20.87kg/mm^2$). The KHN of Ortho-one, $Monolok^2,\;System\;1^+$ significantly decreased after thermocycling (P<0.01). 2. In static shear bond test, three adhesives had no significant differences in the SBS(P>0.01). 3. After thermocycling test, $Monolok^2$ showed the maximum SBS($19.34{\pm}2.75MPa$) and Ortho-one showed the minimum SBS($13.66{\pm}2.23MPa$). The SBS of Ortho-one(P<0.01) and $System\;1^+$(P<0.05) significantly decreased after $10^3$ thermocycles. 4. The SBS of three adhesives after $10^6$ loadcycles were similar and were not significantly decreased compared with static group(P>0.01). 5. The failure sites were usually bracket/resin interface in all groups irrespective of experimental conditions.

• The Journal of Korean Academy of Prosthodontics
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• v.47 no.1
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• pp.61-69
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• 2009

Statement of problem: Porcelain veneers have become a popular treatment modality for aesthetic anterior prosthesis. Fitting porcelain veneers in the mouth usually involve a try-in appointment, which frequently results in salivary contamination of fitting surfaces. Purpose: An in vitro study was carried out to investigate the effect of silane treatment timing and saliva contamination on the resin bond strength to porcelain veneer surface. Material and methods: Cylindrical test specimens (n=360) and rectangular test specimens (n=5) were prepared for shear bond test and contact angle analysis. Whole cylindrical specimens divided into 20 groups, each of which received a different surface treatment and/or storage condition. The composite resin cement stubs were light-polymerized onto porcelain adherends. The shear bond strengths of cemented stubs were measured after dry storage and thermocycling (3,000 cycles) between 5 and $55^{\circ}C$. The silane and their reactions were chemically monitored by using Fourier Transform Infrared Spectroscopy analysis (FTIR) and contact angle analysis. One-way analysis of variance (ANOVA) and Dunnett's multiple comparison were used to analyze the data. Results: FT-IR analysis showed that salivary contamination and silane treatment timing did not affect the surface interactions of silane. Observed water contact angles were lower on the saliva contaminated porcelain surface and the addition of 37% phosphoric acid for 20 seconds on saliva contaminated porcelain increased the degree of contact angle. Silane applied to the porcelain, a few days before cementation, resulted in increasing the bond strength after thermocycling. Conclusion: Within the limitation of this study, it can be concluded that it would be better to protect porcelain prosthesis before saliva contamination with silane treatment and to clean the contaminated surface by use of phosphoric acid.

• Journal of Korean Society of Steel Construction
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• v.20 no.1
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• pp.67-79
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• 2008

In this study, a bending test with three encased composite beams were carried out and analyzed using FEM in order to find how chemical adhesion, interface interlock, friction and composite action by shear studs contribute to stiffness, strength and composite action in the interface of encased compo site beams. The test and results of the FEM analysis showed that the difference in the ultimate moment capacity of the composite beams with and without studs is under 10%. The reason is that the effect of chemical adhesion, interface interlock, and friction in the interface on the composite action is so high that the encased beams have a moment capacity above some defined magnitude. Also, the increment of moment capacity up to plastic moment is not large and the increase of linearly proportioned.