• Journal of the Korean Wood Science and Technology
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• v.35 no.4
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• pp.38-44
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• 2007

As environmental issues is important thing, our study aims to develop natural adhesives made by rosin instead of synthesis adhesive with the formaldehyde emission. Natural adhesives were formulated to enhance curing speed and adhesion performances with various drying agent contents. Adhesion performances were evaluated with tack values measured by texture analyzer and shear strengths determined by single lap shear test. The adhesion performances of nature adhesives developed in this study and compared with those of overseas natural adhesives made by AURO, BioFa, Livos. Optimum drying agent formulation was Co 0.7 part, Zr 1.0 part, Ca 0.5 part, and Activ8 0.1 part. Shear strength of the adhesives manufactured by the optimum drying agent formulation was $93.2{\pm}19.1N/cm^2$.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.130-135
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• 2002

This study investigates the effect of curing method on the bonding strength of aluminum/CFRP composites. The surface of aluminum panel was treated by DC plasma. Lap shear tests and T-peel tests were performed based on the procedure of ASTM 906-94a and ASTMD1876-95, respectively. Test samples were fabricated by using the co-curing method and the secondary curing method. The results showed that the shear strength of test samples made by the co-curing method was 2.5 times greater than that of test samples made by the secondary curing method. The T-peel strength of the co-curing method case was almost 2 times greater than that of the secondary curing method case.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.6
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• pp.159-166
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• 1998

The problem of interface crack in the bonded structures has received a great deal of attention in recent years. In this paper the aluminum bonded single lap-joint containing the interface edge crack is investigated. The tensile load and the average shear stress of the adhesive joints which have different crack length are obtained from the static tensile tests. The critical value of crack length to provoke the interface fracture is determined to a/L=0.4, where a is the interface crack length and L is the adhesive lap-length. The fracture mechanical parameters are introduced to confirm the existence of the critical crack length. The compliance and the stress intensity factors are calculated using the displacement and the stress near the interface crack tip by the boundary element method. These numerical results support the experimental results that the critical value of a/L is 0.4. It is known that the compliance and the stress intensity factors are the efficient parameters to estimate the bonded single lap-joint containing the interface edge crack.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.334-339
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• 2020

In this study, the adhesion properties between aluminum and composite materials, composite materials, and composite materials were compared according to the physical surface treatment to improve mechanical bonding at the bonding surface when considering carbon fiber and glass fiber-reinforced composite materials. Bonded specimens were classified into the type of base material and the surface treatment method of the bonding surface. Sandpaper, sandblasting, and plasma were applied as physical surface treatment methods. The bonded specimen was prepared as a single lap joint test specimen. An experiment to measure the lap shear strength was conducted, and the results were compared. The experimental results confirmed that the mechanical abrasion and sandblasting treatment improved the lap shear strength approximately 4 to 5 fold compared to the general specimen without physical surface treatment. In plasma treatment, the experiment was conducted by defining the respective plasma output and treatment time as follows: 150 W and 5 minutes, 150 W and 10 minutes, and 300 W and 3 minutes. Moreover, the lap shear strength results were similar to the previous mechanical surface treatments. On the other hand, the effect on the adhesion properties was small, depending on the plasma treatment conditions.

• Korean Journal of Materials Research
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• v.5 no.2
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• pp.191-196
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• 1995

Self-bonding strength developed at the interface of amorphous PEEK films is highly sensitive to the processing variables(time, temperature, and pressure) during the bonding process. In order to examine the effects of these processing variables, amorphous PEEK films were bonded at various bonding conditions and the resultant interfacial bond strengths were measured using a modified single lap-shear test. Experimental results showed that the developed self-bonding strength increases with increase in bonding temperature and is directly proportional to the bonding time raised to the 1/4 power. The applied pressure seems only to produce better wetting at the beginning stage of the bonding process. Conclusively, the self-bonding of amorphous PEEK films provides a great potential for developing excellent bond strength approaching the strength of the parent material without any adhesives in structural applications.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.626-629
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• 2004

Recently, the self-healing technique is being investigated to repair the damaged polymeric composites by the use of microcapsules with the healing agent. This technique can obtains both the damage detection and the damage repair simultaneously over the converntional repairing techniques. In this study, the effects of the catalyst ratio to the healing agent and thermal characteristics to the mixtures of healing agent are investigated through single lap shear tests and DSC. The Healing agents such as DCPD, ENB, and their mixtures are considered and Grubb's catalyst is used as a catalst.

• Steel and Composite Structures
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• v.34 no.6
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• pp.877-889
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• 2020

This work features the outcomes of an empirical investigation into the characteristics of steel reinforced grout (SRG) composite - concrete interfaces. The parameters varied were loading rate, densities of steel fibres and types of load displacement responses or measurements (slip and machine grips). The following observations and results were derived from standard single-lap shear tests. Interfacial debonding of SRG - concrete joints is a function of both fracture of matrix along the bond interface and slippage of fibre. A change in the loading rate results in a variation in peak load (P_max) and the correlative stress (σ_max), slip and machine grips readings at measured peak load. Further analysis of load responses revealed that the behaviour of load responses is shaped by loading rate, fibre density as well as load response measurement variable. Notably, the out-of-plane displacement at peak load increased with increments in load rates and were independent of specimen fibre densities.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.1
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• pp.143-150
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• 1998

The evaluation of joint fatigue strength of light weight materials for electrical vehicle body has been performed through single lap joint tests with the design parameters such as joint style, adherend, bonding overlap length and bonding thickness. Fatigue strength was evaluated through 5-Hz, tension-tension, load controlled test with the stress ratio zero value. It is experimentally observed that fatigue strength of joint increases for the increase of overlap length. The combinations of Al-Al and Al-FRP adherends show that fatigue strength of joint is hardly changed for the increase of bonding thickness, but FRP-FRP adherend specimen shows that fatigue strength of joint increases after decreases for the increase of bonding thickness. Al-Al adherend specimen has much higher fatigue length than Al-FRP and FRP-FRP adherend specimens. Riveting at adgesive bonded joint gives little effect on fatigue strength.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.266-269
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• 2004

In this study, bond strengths for the self-healing agents were evaluated through the modified lap shear test in order to suggest the optimal healing conditions for the repair of polymeric composites. The healing agents of DCPD, ENB, and their mixtures were activated with Grubbs' catalysts. According to the results, the mixture of DCPD and ENB gave better opportunity than DCPD only due to the rapid acivation with catalyst in view of the economic and practical use.

• Journal of Welding and Joining
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• v.32 no.3
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• pp.81-88
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• 2014

As the industrial technology has been developed, a dissimilar welding has been received huge attention in various engineering fields. To understand the mechanical properties and possibility of applications of dissimilar metals joining, the laser welding of Cu and Ni dissimilar metals was studied in this paper. Cu and Ni have differences in materials properties, and Cu and Ni make no intermetallic compounds according to typical binary phase of Cu and Ni system. In this study, lap welds of Cu and Ni dissimilar metals using single-mode fiber laser with high welding speed were tried, and mechanical properties of the welds zone were evaluated using a Vickers hardness test and a tensile shear test. To recognize the relation between hardness and tensile shear load, weld fusion zone of interface weld area were observed. And it was confirmed that the ultra-high welding speed could make good weld beads and higher hardness parts had higher tensile shear load under the all conditions.