• Steel and Composite Structures
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• 제29권4호
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• pp.545-555
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• 2018

This study aimed to investigate the flexural behavior of precast concrete (PC) wall - steel shoe composite assemblies with various dry connection details at mid-span. Flexural tests were performed for five scenarios. Test parameters included the width of test specimens, arrangement of steel shoe connectors, and use of structural adhesive or waterproof tape at the mid-span joint. The test results showed that the PC wall - steel shoe composite assemblies joined at mid-span showed flexural damage patterns combined with rotational deformation, and the structural performance was satisfactory regardless of the arrangement of steel shoe connectors. Considering the two deformation components (flexural deformation by bending and rotational deformation due to joint opening), a theoretical model was proposed to analyze flexural strength and joint opening, and the simple model gave good predictions with acceptable accuracy.

• Journal of the Korean Wood Science and Technology
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• 제32권4호
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• pp.46-51
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• 2004

The objective of this study was to evaluate the applicability of high temperature drying to pitch pine (Pinus rigida) lumber, especially intended for use as lamina of structural glued laminated timber (glulam), to enhance the efficient utilization and provide added-value to that species. The high temperature schedule and drying procedures utilized were shown to be reasonable for drying glulam lamina due to the occurrence of small moisture gradients, minimal residual drying stress, and low warpage. Through preliminary tests, it was confirmed that residual resin at lamina surfaces did not adversely affect the gluing process. However, quantitative analysis of resin is required for developing a method to constrain the occurrence of pitch trouble with respect to decreasing long-term adhesive and finish durability of glulam in use after manufacturing. The final moisture content of high temperature dried lamina was much lower than target moisture content and discoloration was more severe than anticipated. In a further study, it will be necessary to determine the optimal drying conditions, such as temperature, humidity, drying time, and top load restraint level, which could best control discoloration, warpage, and moisture content of the lamina, while minimizing fuel expense.

• Journal of the Korea institute for structural maintenance and inspection
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• 제10권6호
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• pp.205-212
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• 2006

In recent investigations, reinforced concrete beams strengthened with Carbon Fiber Sheets (CFS) subjected to fatigue loading were reported to be failed at the ends of CFS by its debonding. U-shaped CFS were attached to both ends of the CFS when fatigue tests on strengthened beams were conducted to delay and/or prevent fatigue failures of adhesive interface. The experimental parameters of this study were the usage of anchorage at the ends of CFS, the number of CFS layers, and the applied load levels of 60%~90% of the static ultimate load obtained from the static tests. The failure modes and the load cycle-deflection relations were observed and discussed from the experimental results. Those results also showed that the U-shaped anchoring system changes the fatigue failure modes and influences greatly on the fatigue capacity of the strengthened beams.

• Journal of the Korea institute for structural maintenance and inspection
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• 제10권5호
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• pp.157-163
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• 2006

This study is on the evaluation of double surface protection method using water repellent primer and final top coat to protect concrete. Water repellent agent has been applied on the final top coat to protect concrete. However, to make up for the weakness to the ultraviolet of the water repellent, the work procedure of these protectors is done vice versa. This combination of protectors was compared with existing ones in this study. Even though the final top coat was applied on the water repellent primer, its adhesive strength met to KS F 4936-' 03 with other protectors used in this study. All surface protectors used in this study were excellent in protecting concrete. Especially, in case of applying with final top coat in conjunction with water repellent primer, the resistance against chloride ion penetration and neutralization by $CO_2$ was more efficient than other surface protectors used in this study under this given condition.

• Structural Engineering and Mechanics
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• 제48권4호
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• pp.479-500
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• 2013

This paper presents the experimental as well as analytical study conducted on layer-bonded scrap tire rubber pad (STRP) isolators to develop low-cost seismic isolators applicable to structures in developing countries. The STRP specimen samples were produced by stacking the STRP layers one on top of another with the application of adhesive. In unbonded application, the STRP bearings were placed between the substructure and superstructure without fastening between the contact surfaces which allows roll-off of the contact supports. The vertical compression and horizontal shear tests were conducted with varying axial loads. These results were used to compute the different mechanical properties of the STRP isolators including vertical stiffness, horizontal effective stiffness, average horizontal stiffness and effective damping ratios. The load-displacement relationships of STRP isolators obtained by experimental and finite element analysis results were found to be in close agreement. The tested STRP samples show energy dissipation capacity considerably greater than the natural rubber bearings. The layer-bonded STRP isolators serve positive incremental force resisting capacity up to the shear strain level of 150%.

• Journal of the Microelectronics and Packaging Society
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• 제25권2호
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• pp.9-17
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• 2018

Aluminum (Al) and its alloys have been used widely in a variety of industries such as structural, electronic, aerospace, and particularly automotive industries due to their lightweight characteristic, outstanding ductility, formability, high oxidation and corrosion resistance, and high thermal and electrical conductivity. Al have different kinds of alloys according to the various additional elements system and they should be selected properly depending on their effectiveness and suitability for their particular purpose. The major elements for Al alloys are silicon (Si), magnesium (Mg), manganese (Mn), copper (Cu), and zinc (Zn). In order for Al alloys to use for each industry, it is necessary to study of Al to Al joining and/or the Al to dissimilar materials joining to combine the individual parts into one. Many studies on joining technologies about Al to Al and Al to dissimilar materials have been performed such as press joining, bolted joint, welding, soldering, riveting, adhesive bonding, and brazing. This study reviews a variety of Al alloys and their joining method including its principles and properties with recent trends.

• Transactions of the Korean Society of Mechanical Engineers A
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• 제26권11호
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• pp.2374-2382
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• 2002

Aluminum alloy/aramid fiber reinforced plastic(Al/AFRP) laminates consists of high strength metal(A15052) and laminated aramid fiber with structural adhesive bond. The mixture ratio effect of epoxy resin curing agent accelerator on the tensile strength and T-peel strength characteristic in Al AFRP laminates were investigated in this study. The epoxy. diglycidylether of bisphenol A(DCEBA), It'as cured by methylene dianiline(MDA) with or without an accelerator(K-54). Eight different kinds of resin mixture ratios were selected for the test , five kinds of Al/AFRP laminates were named as Al/AFRP(1) and three others of Al/AFRP laminates were named as Al/AFRP(2). The comparison of tensile strength and T-peel strength with variation of resin mixture ratio were studied. Respectively. Al/AFRP(1) and Al/AFRP(2) indicated approximately 6.0 times and 7.0 times more improved maximum tensile strength in comparison with those of monolithic A15052. Al/AFRP(2) indicated approximately 1.5 times more impoved maximum T-peel strengths in comparison with those of Al/AFRP(1). As results. Al/AFRP(2) turned out to have more effective characteristics on the tensile strength and T-peel strength than those of Al/AFRP(1).

• Applied Microscopy
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• 제43권1호
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• pp.14-20
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• 2013

The leopard danio, Danio rerio var. frankei is a spotted color morph of the zebrafish, Danio rerio caused by a pigment mutation. The structural differences of fertilized egg and egg envelope are poorly documented. To clarify this, we compared the fertilized egg morphology and ultrastructures of surface structures, the micropyle and the cross section of fertilized egg envelopes of zebrafish and leopard danio, variation species of zebrafish using a light and electron microscopes. Although the fertilized egg sizes were different, the external shapes of the fertilized eggs of two species couldn't be differentiated under the light microscope. The characteristics of fertilized eggs, such as a spherical shape, a non-adhesive quality and a large perivitelline space, were shown to be related to spawning habit. In ultrastructure of fertilized egg envelope, there is no morphological difference of micropyle between two species. By contrast, the ultrastructure and the numbers of knob-like structures and semihemisphere-like structures per unit area on the outer surface, and the number of lamellae of inner layer on the fertilized egg envelope section displayed definite species specificity. Collectively, our data indicate that the ultrastructure of fertilized egg envelope in the zebrafish could be differentiated by species variation.

• Journal of the Society of Disaster Information
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• 제12권1호
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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.

• Transactions on Electrical and Electronic Materials
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• 제8권2호
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• pp.89-92
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• 2007

$CuInSe_2$ thin film were prepared in order to clarify optimum conditions for growth of the thin film depending upon process, and then by changing a number of deposition conditions and heat treatment conditions variously, structural and electrical characteristics were measured. Thereby, optimum process variables were derived. For the manufacture of the $CuInSe_2$, Cu, In and Se were deposited in the named order. Among them, Cu and In were deposited by using the sputtering method in consideration of their adhesive force to the substrate, and the DC/RF power was controlled so that the composition of Cu and In might be 1:1, while the annealing temperature having an effect on the quality of the thin film was changed from $200\;^{\circ}C$ to $350\;^{\circ}C$ at intervals of $50\;^{\circ}C$.