• Journal of Fashion Business
• /
• v.16 no.1
• /
• pp.52-68
• /
• 2012

To achieve the aim of this study, 9 different types of samples were made to examine mechanical property according to structured pattern and type of Machi of pullover armhole of WholeGarment(seamless knitwear). With respect to samples, from which comparisons are made and anaylzed among basic characteristics of material, tensile strength & elongation and residual elongation due to repeated extension of armhole connecting part, the following conclusions could be obtained. It's revealed that the tensile strength of Machi part as being armhole connecting part of samples is more affected by Machi type than pattern structure. Of Machi types, it showed stronger tensile strength in the order of Normal(Normal Machi)< Machi_B(unilateral Machi)

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.28 no.6A
• /
• pp.809-817
• /
• 2008

Recently, the external prestressing method is being much frequently used in strengthening reinforced concrete structures because of it's excellent load resistance and serviceability increases comparing to other strengthening methods. However, it is true that the research on fatigue performance of concrete structures strengthened by the external prestressing using FRP tendons is rare. Therefore, the purpose of this study is to evaluate the safety and feasibility of the external prestressing method by analyzing the characteristics of the reinforced concrete beam strengthening using FRP tendons under repeated loads. Test variables adopted in this experimental study are the types of external prestressing material (steel or FRP tendon) and the repeated load ranges. The repeated load range have the minimum 50% of yield load of reinforced concrete beam and the maximum 70-85%. The test beams are loaded by 4 point loadings with 3 Hz sine wave. From this experimental study, it is confirmed that the reinforced concrete beams strengthened using FRP tendons have sufficient safety against fatigue, especially in FRP tendon itself, tendon at deviators and tendon at anchorages.

• Structural Engineering and Mechanics
• /
• v.70 no.1
• /
• pp.67-80
• /
• 2019

Strengthening with near surface mounted carbon fibre reinforced polymers (NSM-CFRP) is a strengthening technique that have been used for several decades to increase the load carrying capacity of reinforced concrete members. In Iraq, many concrete buildings and bridges were subjected to a wide range of damage as a result of the last war and many other events. Accordingly, there is a progressive increase in the strengthening of concrete structures, bridges in particular, by using CFRP strengthening techniques. Near-surface mounted carbon fibre polymer has been recently proved as a powerful strengthening technique in which the CFRP strips are sufficiently protected against external environmental conditions especially the high-temperature rates in Iraq. However, this technique has not been examined yet under repeated loading conditions such as traffic loads on bridge girders. The main objective of this research was to investigate the effectiveness of NSM-CFRP strips in reinforced concrete beams under repeated loads. Different parameters such as the number of strips, groove size, and two types of bonding materials (epoxy resin and cement-based adhesive) were considered. Fifteen NSM-CFRP strengthened beams were tested under concentrated monotonic and repeated loadings. Three beams were non-strengthened as reference specimens while the remaining were strengthened with NSM-CFRP strips and divided into three groups. Each group comprises two beams tested under monotonic loads and used as control for those tested under repeated loads in the same group. The experimental results are discussed in terms of load-deflection behavior up to failure, ductility factor, cumulative energy absorption, number of cycles to failure, and the mode of failure. The test results proved that strengthening with NSM-CFRP strips increased both the flexural strength and stiffness of the tested beams. An increase in load carrying capacity was obtained in a range of (1.47 to 4.49) times that for the non-strengthened specimens. Also, the increase in total area of CFRPs showed a slight increase in flexural capacity of (1.02) times the value of the control strengthened one tested under repeated loading. Increasing the total area of CFRP strips resulted in a reduction in ductility factor reached to (0.71) while the cumulative energy absorption increased by (1.22) times the values of the strengthened reference specimens tested under repeated loading. Moreover, the replacement of epoxy resin with cement-based adhesive as a bonding material exhibited higher ductility than specimen with epoxy resin tested under monotonic and repeated loading.

• Journal of the Korean Geotechnical Society
• /
• v.21 no.10
• /
• pp.85-97
• /
• 2005

Despite a number of advantages of reinforced earth walls over conventional concrete retaining walls, there exist concerns over long-term residual deformation when subjected to repeated and/or cyclic loads, especially when used as part of permanent structures. In view of these concerns, in this paper time-dependent deformation characteristics of geosynthetic reinforced soil under sustained and/or repeated loads were investigated using a series of plane strain compression tests on geogrid reinforced weathered granite soil specimens. The results indicate that sustained or repeated loads can yield appreciable magnitudes of residual deformations, and that the residual deformations are influenced not only by the loading characteristics but by the mechanical properties of geogrid. It is also found that the preloading technique can be effectively used in controlling residual deformations of reinforced soils subjected to sustained and/or repeated loads.

• The Korean Journal of Applied Statistics
• /
• v.22 no.1
• /
• pp.181-188
• /
• 2009

This paper discusses the covariance structures of data collected from an experiment with a nested design structure, where a smaller experimental unit is nested within a larger one. Due to the nonrandomization of repeated measures factors to the nested experimental units, compound symmetry covariance structure is assumed for the analysis of data. Treatments are given as the combinations of the levels of random factors and fixed factors. So, a mixed-effects model is suggested under compound symmetry structure. An example is presented to illustrate the nesting in the experimental units and to show how to get the parameter estimates in the fitted model.

• Fashion & Textile Research Journal
• /
• v.14 no.1
• /
• pp.122-129
• /
• 2012

To develop a waterproof breathable material, we fabricated three kinds of nanofiber web laminates using a massproduced electrospun nanofiber web with different substrates and layer structures. The waterproofness and breathability of nanofiber web laminates were evaluated after repeated launderings and compared with those of conventional waterproof breathable fabrics currently in use, including densely woven fabric, microporous membrane laminated fabric, and coated fabric. The durability of nanofiber web laminates, including adhesion strength, abrasion resistance, tensile strength, and tearing strength, was also assessed and compared with those of conventional waterproof breathable fabrics. The water vapor transmission of nanofiber web laminates increased slightly after repeated launderings, whereas the air permeability somewhat decreased after launderings but still maintained an acceptable level of air permeability. Laundering reduced the resistance to water penetration of nanofiber web laminates, which implies that laminating techniques or substrate materials that could support waterproofness of the laminated structure should be explored. The adhesion strength, abrasion resistance, tensile strength, and tearing strength of nanofiber web laminates were in a range comparable to conventional waterproof breathable materials.

• Proceedings of the KSR Conference
• /
• 2011.10a
• /
• pp.2902-2909
• /
• 2011

Regional torrential rains in summer this year due to abnormal climate changes compared to last year, have been frequent. Since Typhoon Rusa and Typhoon Maemi resulted in major damage to railroad facilities in 2002 and 2003 consecutively, problems with abnormal climate changes became a global problem including railroad and floods and droughts around the globe, heavy snow and winter warming have been repeated until now. Serious problem of radiation leakage in Fukushima nuclear power plant by the Tsunami due to 9.0-scale earthquake, this year in March, in northeastern Japan happened, and has given an impact on the life of Japanese citizens and industries and has also influenced on Korean. This shows how important to secure and to protect major national facilities including railroad structures to natural disasters such as earthquake. Therefore, we will briefly discuss about technologies for securing and protecting railroad structures to earthquakes, floods and other natural disasters.

• Journal of the Korean Society of Safety
• /
• v.12 no.3
• /
• pp.120-131
• /
• 1997

This paper presents an approximate reanalysis methods of structures based on substructuring for an effective optimization of large-scale structural systems. In most optimal design procedures the analysis of the structure must be repeated many times. In particular, one of the main obstacles in the optimization of structural systems are involved high computational cost and expended long time in the optimization of large-scale structures. The purpose of this paper is to evaluate efficiently the structural behavior of new designs using information from previous ones, without solving basic equations for successive modification in the optimal design. The proposed reanalysis procedure is combined Taylor series expansions which is a local approximation and reduced basis method which is a global approximation based on substructuring. This technique is to choose each of the terms of Taylor series expansions as the basis vector of reduced basis method in substructuring system which is one of the most effective analysis of large -scale structures. Several numerical examples illustrate the effectiveness of the solution process.

• Computers and Concrete
• /
• v.9 no.2
• /
• pp.99-118
• /
• 2012

Marine Structures are very costly and need a continuous inspection and maintenance routine. The most effective way to control the structural health is the application of an expert system that can evaluate the importance of any distress on the structure and provide a maintenance program. An extensive literature review, interviews with expert supervisors and a national survey are used to build a decision support system for concrete structures in sea environment. Decision trees are the main rules in this system. The system input is inspection information and the system output is the main cause(s) of distress(es) and the best repair method(s). Economic condition, severity of distress, distress situation, and new technologies and the most repeated classical methods are considered to choose the best repair method. A case study demonstrates the application of the developed decision support system for a type of marine structure.

• Journal of Power System Engineering
• /
• v.19 no.3
• /
• pp.55-62
• /
• 2015

This paper discusses a new model for investigating the micro-mechanical behavior of beam-like structures composed of various elastic moduli and complex geometries varying through the cross-sectional directions and also periodically-repeated along the axial directions. The original three-dimensional problem is first formulated in an unified and compact intrinsic form using the concept of decomposition of the rotation tensor. Taking advantage of two smallness of the cross-sectional dimension-to-length parameter and the micro-to-macro heterogeneity and performing homogenization along dimensional reduction simultaneously, the variational asymptotic method is used to rigorously construct an effective zeroth-order beam model, which is similar a generalized Timoshenko one (the first-order shear deformation model) capable of capturing the transverse shear deformations, but still carries out the zeroth-order approximation which can maximize simplicity and promote efficiency. Two examples available in literature are used to demonstrate the consistence and efficiency of this new model, especially for the structures, in which the effects of transverse shear deformations are significant.