• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.205-220
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• 1997

The objective of this study is to investigate the structural behavior of concrete-filled steel tubular column-H beam connections with exterior stiffeners. As a preliminary test, simple tensile test on the column to H-beam flange connections stiffened were conducted The paramaters of tensile test are the thickness(T=9, 12, 15m) and the width(W=50, 75, 100, 150mm) of exterior stiffeners. The simple tensile test were conducted to 7 kinds of specimens. Estimating the load, displacement, and strain from each kind, results of simple tensile test were compared with results of second test. On the basis of simple tensile test, test on the column to H-km connections stiffened with the sames under monotonic and cyclic load were conducted. Specimens of 5 for the second experiment were made. In analysis, comparing each strengthes and stiffnesses we estimated deformation capacity. Comparing and estimating each yielding strength ratios and maxium-strength ratios on the basis of yield line theory, new strength formula of beam-to-column connections was suggested.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.112-117
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• 2016

This research compared the tensile performance of the vegetation mat, which was developed byu using the rapidly growing biodegradable plastic, Poly Lactic Acid(PLA), according to the biodegradation period. The test applied the method defined by Korean Standard KS. In the result of experiment using single-material PLA mesh and PLA plastic, the tensile strength and molecular weight were inverse-proportional to the 5 months of biodegradation period. The thickness of PLA mesh was increased by 11.2~13.4% while the tensile strenth of it was reduced by 32.4~55.4%. The tensile strength and molecular weight of PLA plastic were also reduced over time. However, the tension test of vegetation mat comprised of PLA mesh, non-woven fabric (including seeds), and jute net didn't have specific tendency.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.198-203
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• 2020

Cracking due to material behavior like drying shrinkage easily occurs since tensile strength in concrete is very low at initial curing stage. In this paper, workability such as air content and slump was evaluated on CFC(Cellulose Fiber Concrete) with 0.0 ~ 2.0% of fiber addition, and the tests for tensile/compressive strength were performed. With increasing addition ratio of fiber, air content and slump kept similar level to 1.0kg/㎥ of addition ratio, and this trend was effective to 2 hours after mixing. Strength was enhanced with increasing addition ratio, which showed 7.0 ~ 9.0% for compressive strength and 7.0 ~ 22.0% for tensile strength, respectively. The tensile strength increased relatively more, which show the addition of cellulose fiber was very effective to crack resistance. The workability in CFC can be guaranteed for 2 hours in the following conditions like 2 minutes of mixing period and 1.0kg/㎥ of addition ratio of fiber.

• Elastomers and Composites
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• v.52 no.4
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• pp.257-265
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• 2017

In this work, CR (Chloroprene Rubber) was emulsified by phase-inversion emulsification with nonionic surfactants (NP-1025, LE-1017, and OP-1019) and an anionic surfactant (SDBS; sodium dodecylbenzenesulfonate), and its stabilization was investigated through a study of its adsorption characteristics, zeta potential, and flow behavior. As the amount of the mixed surfactant increased, the droplet size decreased, resulting in the increase of viscosity. In particular, a CR emulsion with a lower absorbance in the UV spectrum exhibited the highest zeta potential. The results of this experiment showed that the CR emulsion prepared using (LE-1017) and SDBS was the most stable. In this study, calcium hydroxide and aluminum hydroxide were added to enhance the mechanical properties of the CR emulsion, and the relationship between tensile strength, tear strength and surface free energy were investigated. The tensile and tear strengths of the CR emulsion incresed as the amount of calcium hydroxide and aluminum hydroxide increased. The highest tensile and tear strengths and surface free energy were observed for additions of 1.0% calcium hydroxide and 0.80% aluminum hydroxide, respectively. It was concluded that the interfacial bonding strength was improved by the even dispersion of calcium hydroxide and aluminum hydroxide in the CR emulsion.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.6 s.165
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• pp.988-1000
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• 1999

An experimental study is presented for the effect of number of terms of a pewee series type stress function on stress analysis around a hole in tensile loaded plate. The hybrid method coupling photoelastsic data inputs and complex variable formulations involving conformal mappings and analytical continuity is used to calculate tangential stress on the boundary of the hole in uniaxially loaded, finite width tensile plate. In order to measure isochromatic data accurately, actual photoelastic fringe patterns are two times multiplied and sharpened by digital image processing. For qualitative comparison, actual fringes are compared with calculated ones. For quantitative comparison, percentage errors and standard deviations with respect to percentage errors are caculated for all measured points by changing the number of terms of stress function. The experimental results indicate that stress concentration factors analyzed by the hybrid method are accurate within three percent compared with ones obtained by theoretical and finite element analysis.

• Journal of the Korean Applied Science and Technology
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• v.30 no.3
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• pp.567-574
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• 2013

For this research, prepared water soluble milk casein resin and waterborne polyurethane-acrylic resin. Use these resin, this article has been analyzed about change of mechanical properties by increasing amount of casein resin in polyurethane-acrylic resin on coated leather. According to measure data for solvent resistance, WPA(waterborne polyurethane-acrylic resin) resin and WPA-C1, C2, C3(samples of polyurethane-acrylic resin with milk casein resin) had good property. As known in the results, increase of casein constant did not influence to big change of hybrid resin properties. As test of tensile strength, WPA had lowest tensile characteristic(1.598 $kg_f/mm^2$) and WPA-C3 had highest tensile characteristic(1.718 $kg_f/mm^2$). Also best properties of abrasion was WPA-C3(06.021 mg.loss). In elongation case, WPA had best properties(754 %) in this experiment.

• Journal of the Korea Fashion and Costume Design Association
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• v.15 no.2
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• pp.57-64
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• 2013

As the clothing materials have been more functional and advanced, the cotton fabrics for dress shirts or blouses have been more qualified and the sewability for high degree of completion has been required. This study aims to identify the seam strength depending on the change of stitch density of fine cotton fabrics by fabric and thread and so the general seam performance of fine cotton fabrics by analyzing the seam efficiency and breaking mode of seams. For an experiment, 3 kinds of fine cotton fabrics and 2 kinds of threads were selected and the sample was made by changing the stitch density by four steps. Then, the seam strength was measured. Next, the seam efficiency and breaking mode of seams were analyzed on the basis of the results of seam strength measurement. The results are as follows: All fabrics showed the similar tendency in seam strength. The seam strength is related to the tensile strength and thread strength, it increased only to a certain stitch density. When the stitch density exceeded a certain level, fabrics were destroyed or threads were cut. Then, the seam strength didn't increase. Furthermore, the more the seam strength increased, the more the seam efficiency increased. For increasing the maximum stitch density, it was required to use the fabrics and threads which had similar properties, in other words, the high thread strength for the high tensile strength and the low thread strength for the high tensile strength.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.9
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• pp.931-942
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• 2013

In this study, we analyzed and compared the ultrasonic welding with the laser welding for the pure aluminium thin plates in a series of secondary lithium-ion batteries which are currently being produced by the ultrasonic welding; and performed the experiment for the purpose of the preceding study to replace the ultrasonic welding method with the laser welding method. As a result, the weld width of ultrasonic welding was 5mm, but that of laser welding was about 1~1.5 mm. As a result of tension test, the tensile strength was high when the pulse duration hour was short at the low peak power, while the high tensile strength was achieved when the pulse duration hour was long at the high peak power. The value of tensile strength was higher in the ultrasonic welding while the laser welding showed a maximum 45% better result as for the welding width.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.2
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• pp.1-9
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• 2001

To measure springback ratio of thin sheet or plate, winding bend rig is made. It bends a specimen with keeping its curva-ture constant and measure the bending angles before and after release of bending load. To check the performance of the bend rig, we calculated the bending moment by two ways which are based on simple beam theory. One is that the bending moment is calculated by using the results of bending test, and the other is that the moment is calculated by using the results of tensile tests. The former may entails the effect of the other is that the moment is calculated by using the results of tensile tests. The former may entails the effect of the friction between bending pin of the rig and surface of specimen, but the latter does not contain any effects of the friction since the bending moment is obtained by using tensile tests. Never-theless, the values of the two bending moments shows the same level of bending moment, which implies that the friction does not influence on the presence of friction within the scope of the test performed in this experiment. This phenomenon is explained theoretically by using moment equilibrium.

• Journal of Power System Engineering
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• v.19 no.4
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• pp.11-16
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• 2015

Welding is very popular method for joining two or more metals. In this paper, the three-way factorial design was adopted for obtaining the optimum friction stir welding conditions of Al 5052 alloy. Tools of shoulder diameter of 9, 12, 15 mm and pin length of 1.5 mm were used. Also the material's dimension for welding was $100{\times}100{\times}2mm$, and the tensile specimens were worked by water-jet technique. Welding variables were shoulder diameter, rotating speed of tool and welding speed. As far as this work is concerned, optimum condition for friction stir joint of Al 5052 alloy was predicted as the shoulder diameter of 15 mm, welding speed of 500mm/min and rotating speed of 1000 rpm. In addition, the presumed range of tensile strength under the optimal conditions is estimated to be $208.3{\pm}5.7$ MPa with 99% reliability.