• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.4
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• pp.553-565
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• 2001

One-bottle adhesive system was recently developed in order to simplify the clinical skills and save chair time after continuous improvements on dentin bonding agents. To test the shear bond strength of a new "one-bottle adhesive" system to bovine dentin various commercially available one-bottle adhesives(Prime & Bond $2.1^{(R)}$, One Coat $Bond^{(R)}$, Syntac $Sprint^{(R)}$, Single $Bond^{(R)}$) were included for comparison. And we observe the interfacial morphology by scanning electron microscope. The results were as follows; 1. Group II (One Coat $Bond^{(R)}$) showed higher shear bond strength than group I (Prime & Bond $2.1^{(R)}$), group III(Syntac $Sprint^{(R)}$), and group IV(Single $Bond^{(R)}$), but no statistically significant difference was founded between groups(p>.05). 2. Relating reverse-cone shape resin tags were observed in samples of all groups under SEM. We could observed hybrid layer, resin tag and many lateral branches in every group. But, we observed in group III rare lateral branched than other three groups, and discontinuous hybrid layer.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.176-181
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• 1990

For the purpose of the improvement of interfacial shear strength in carbon fiber/aluminum matrix composite material, polyacrylonitrile-based carbon fibers were surface treated by hydrogen sulfide gas continuously between 400 and $600^{\circ}C$. Surface treated carbon fibers were analysed by scanning electron microscope. The existence of sulfur compound on treated carbon fiber surfaces was confirmed, and carbon and oxygen contents of the fiber surfaces were examined by X-ray photoelectron spectroscopy. Optimum treating temperature for the adsorption of sulfur on the carbon fiber surface was $500^{\circ}C$. Sulfur compounds on the carbon fiber surfaces form the structures of disulfide, $(S)_n$ and thiophene. The decrease in the tensile strength of the carbon fibers was observed less than about 5%.

• Steel and Composite Structures
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• v.17 no.6
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• pp.929-949
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• 2014

Thirty one push-out tests were carried out in order to investigate the bond behavior between shape steel, steel tube (named steels) and recycled aggregate concrete (RAC), including 11 steel reinforced recycled aggregate concrete (SRRAC) columns, 10 recycled aggregate concrete-filled circular steel tube (RACFCST) columns and 10 recycled aggregate concrete-filled square steel tube (RACFSST) columns. Eleven recycled coarse aggregate (RCA) replacement ratios (i.e., 0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) were considered for SRRAC specimens, while five RCA replacement ratios (i.e., 0%, 25%, 50%, 75% and 100%), concrete type and length-diameter ratio for recycled aggregate concrete-filled steel tube (RACFST) specimens were designed in this paper. Based on the test results, the influences of all variable parameters on the bond strength between steels and RAC were investigated. It was found that the load-slip curves at the loading end appeared the initial slip earlier than the curves at the free end. In addition, eight practical bond strength models were applied to make checking computations for all the specimens. The theoretical analytical model for interfacial bond shear transmission length in each type of steel-RAC composite columns was established through the mechanical derivation, which can be used to design and evaluate the performance of anchorage zones in steel-RAC composite structures.

• Transactions of Materials Processing
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• v.32 no.3
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• pp.107-113
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• 2023

The importance of dual-fuel engines has increased for reducing CO₂ emissions. However, the low operating temperature of this engine may induce low-temperature corrosion at combustion parts, which reduces the engine service life. To overcome this problem, NiCr38Al4 alloy was developed for valve spindle, but the cost of this alloy is expensive due to its high Cr content. For reducing the manufacturing cost of valve spindle, in the present work, NiCr38Al4 alloy was welded with Nimonic80A alloy by conducting friction welding. The tensile test results show that the strength of friction-welded specimens follows the properties of the lower-strength parent materials, without severe cracks at the interface. The large shear strain and frictional heat from friction welding not only reduce grain size but also induce solute element diffusion at the interfacial region. Because of the low Cr diffusivity compared with Ti, Cr carbides were not observed in the Nimonic80A matrix, while Ti carbides were distributed in both the Nimonic80A and SNCrW matrices.

• Steel and Composite Structures
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• v.44 no.4
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• pp.519-529
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• 2022

Sandwich structures with the superior mechanical properties such as high stiffness and strength-to-weight ratio, good thermal insulation, and high energy absorption capacity are used today in aerospace, automotive, marine, and civil engineering industries. These structures are composed of moderately stiff, thin face sheets that withstand the majority of transverse and in-plane loads, separated by a thick, lightweight core that resists shear forces. In this research, the finite element technique is used to simulate a sandwich panel with a truss core under axial compressive stress using ABAQUS software. A review of past experimental studies shows that the bondline between the core and face sheets plays a vital role in the critical failure load. Therefore, this modeling analyzes the damage initiation modes and debonding between face sheet and core by cohesive surface contact with traction-separation model. According to the results obtained from the modeling, it can be observed that the adhesive stiffness has a significant influence on the critical failure load of the specimens. To achieve the full strength of the structure as a continuum, a lower limit is obtained for the adhesive stiffness. By providing this limit stiffness between the core and the panel face sheets, sudden failure of the structure can be prevented.

• Journal of Dental Rehabilitation and Applied Science
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• v.28 no.1
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• pp.67-78
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• 2012

The purpose of this study was to determine whether there were differences in shear bond strength to human dentin using IDS technique compared with DDS. Forty freshly extracted human molars were and devided into 4 groups. The control group specimens were, on the morrow of tooth preparation, light-cured after application of dentin bonding agent and cemented with resin cement. The IDS/SE(immediate dentin sealing, Clearfil$^{TM}$ SE Bond) and IDS/SB (immediate dentin sealing, Adapter$^{TM}$ Single Bond 2) specimens were, on the morrow of tooth preparation, light-cured after application of dentin bonding agent(Clearfil$^{TM}$ SE Bond and Adapter$^{TM}$ Sing Bond 2, respectively), whereas DDS specimens were not treated with any dentin bonding agent. IDS/SE, IDS/SB and DDS specimens were thermocycled. Following that delay, specimens were cemented with resin cement. The dentin bonding agent was left unpolymerized until the application of porcelain restoration. Shear bond strengths were measured using a universal testing machine. Specimens also were evaluated for mode of fracture using an optical microscope. The mean shear bond strengths of control group and IDS/SE groups were not statistically different from one another. The bond strength of IDS/SE group had a significantly higher mean than that of DDS group. There was no significant difference in the mean shear bond strength between IDS/SB(4.11MPa) and DDS group. The evaluation of failure modes indicates that most failures in the control group and IDS/SE groups were mixed, whereas failures in the DDS group were interfacial. When preparing teeth for indirect ceramic restoration, IDS with Clearfil$^{TM}$ SE Bond results in improved shear bond strength compared with DDS.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.47-76
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• 1994

This study was carried out to evaluate the effect of the crack propagation characteristics and bond stress of ceramo-metal system. In order to characterize the crack propagation, the static crack propagation stored in $37^{\circ}C$ distilled water of two commerical porcelains and the dynamic crack propagation under cyclic flexure load of ceramo-metal system were examined. In order to characterize the bond stress, the shear bond test, the 3-point flexure bond test, and the finite element stress analysis of ceramo-metal system were conducted. The results obtained were as follows : 1. Bulk densities and Young's moduli of opaque porcelains increased with repeated firing. 2. Maximum fracture toughness during 4 firing cycles showed at the group of 4 firing cycles in Ceramco porcelain and 2 firing cycles in Vita porcelain. 3. Shear bond strength and flexure bond strength of Ceramco-Verabond specimen were larger than those of Ceramco-Degudent G specimen (p<0.05). 4. Interfacial stresses under three point flexure bond test were concentrated at the edges of ceramometal system. 5. When a cyclic flexure load was applied, the crack growth rate of porcelain surface of ceramometal specimens was decreased as load cycles increased.

• Journal of the Korea Concrete Institute
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• v.28 no.5
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• pp.535-544
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• 2016

This paper aims at examining the effects of sustained load and elevated temperature on the time-dependent deformation of a carbon fiber reinforced polymer (CFRP) sheets bonded to concrete as well as the pull-off strength of single-lap shear specimens after the sustained loading period using digital images. Elevated temperature during the sustained loading period resulted in increased slip of the CFRP composites, whereas increased curing time of the polymer resin prior to the sustained loading period resulted in reduced slip. Pull-off tests conducted after sustained loading period showed that the presence of sustained load resulted in increased pull-off strength and interfacial fracture energy. This beneficial effect decreased with increased creep duration. Based on analysis of digital images, results on strain distributions and fracture surfaces indicated that stress relaxation of the epoxy occurred in the 30 mm closest to the loaded end of the CFRP composites during sustained loading, which increased the pull-off strength provided the failure locus remained mostly in the concrete. For longer sustained loading duration, the failure mode of concrete-CFRP bond region can change from a cohesive failure in the concrete to an interfacial failure along the concrete/epoxy interface, which diminished part of the strength increase due to the stress relaxation of the adhesive.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.3
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• pp.298-307
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• 2010

The purpose of this study was to assess the effect on oxygen inhibition layer(OIL) for the interfacial bonding between resin composite layers, including shear bond strength, fracture modes and degree of conversion. The first layer of specimen was filled with Z-250(shade A3) and was cured for 40s. The second layer of specimen was filled with same composite(shade A1) and was cured for 40s. The first layer of specimens for each group were prepared by methods as followings. Control(curing in atmospheric air), Group1(curing against Mylar strip), Group2(scrubbed with a acetone-soaked cotton), Group3(using Tescera light cup), Group4(using Tescera heat cup), Group5(stored in disti1led water for 30days at $37^{\circ}C$), Group6 (using bonding agent). The results were as follows: 1. There was no statistically significant different shear bond strength between control and group 1(p>0.05). 2. Group 2 showed significantly lower shear bond strength than control and group 1(p<0.05). 3. The observation of the fracture surface leads to the evidence that a major difference occurs in the case of control, group1 and group 3 samples which break mainly cohesively while the other groups break in majority adhesively. 4. The results of FTIR showed that the degree of conversion was the highest in group 2 and the lowest in control group(p<0.05). It can be concluded that an OIL is not necessary for bonding with composite resin. But if a reduced critical amount of the unreacted monomer is present, it was detrimental to bonding additional layers of composite. Further study, such as the quantitative analysis of the unreacted monomer are required.

• Journal of Dental Rehabilitation and Applied Science
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• v.24 no.1
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• pp.41-56
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• 2008

The methods of surface modification of commercial implants were various according to the manufacturer. Surface modification of implant may produce diverse physical and chemical surface characteristics resulted from the treatment method and treatment condition. As a result, the bone response might be different. Even though surface modified implants have been used clinically, most researches are focusing on the bone response of surface modified implants comparing to machined implants rather than surface modified commercial implants. This study compare and analyze bone responses of 4 surface modified commercial implants with different shapes and surfaces. Eighty surface modified commercial implants with 4 different surface characteristics were installed in the tibia of white Newzealand rabbits. Biomechanical stability tests and histomorphometric evaluation were done. The results were as follows: 1. Surface modified commercial implants showed stable osseointegration at 6 weeks after installation. 2. Histomorphometric evaluation showed that there was no significant differences in bone to implant contact among 4 different commercial titanium implants. In comparing the implants with different shape the measurement of bone growth in subcortical area would be more reliable than entire bone to implant contact length. 3. Resonance Frequency Analysis showed that there was no significant differences among 4 types of implants, even though they were significantly different in installation. 4. There was significant differences in interfacial shear strength among 4 type of implants. 5. It is difficult to observe accurate bone to implant interface using Micro-CT. However, it is possible to measure the entire contact length of the implant to the bone.