• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.29-39
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• 2002

In order to evaluate the behavior of overall range from small strain to failure, the triaxial compression tests with LVDTs were performed for local displacement measurements. According to the result it was possible to evaluate the total range behavior from 0.001% to 10% and both secant moduli of undisturbed and disturbed weathered soils had a similar result in the small slain level. The normalized shear moduli$(G/G_{max})$ in the undrained triaxial compression tests were similar to those of resonant column tests but the maximum shear moduli$(G/G_{max})$ were strongly affected by the ratio of saturation. As a result of parametric study a constitutive model with anisotropic hardening could predict the behavior of total strain range.

• Structural Engineering and Mechanics
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• v.72 no.5
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• pp.569-583
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• 2019

Tubular steel sections are widespread all over the world because of their strength and aesthetic appearance. Tubular steel members may exhibit local buckling such as elephant foot or overall buckling under extreme compression load. Recently, external bonding of fiber reinforced polymers (FRP) sheets for strengthening these members has been explored through experimental research. This paper presents three-dimensional nonlinear finite element analysis (FEA) to investigate the structural behavior of strengthening tubular steel members with FRP against local and overall buckling phenomena. Out-of-roundness and out-of-straightness imperfections were introduced to the numerical models to simulate the elephant foot and overall buckling, respectively. The nonlinear analysis preferences such as the integration scheme of the shell elements, the algorithm for solution of nonlinear equations, the loading procedure, the bisection limits for the load increments, and the convergence criteria were set, appropriately enough, to successfully track the sophisticated buckling deformations. The agreement between the results of both the presented FEA and the experimental research was evident. The FEA results demonstrated the power of the presented rigorous FEA in monitoring the plastic strain distribution and the buckling phenomena (initiation and propagation). Consequently, the buckling process was interpreted for each mode (elephant foot and overall) into three sequential stages. Furthermore, the influence of FRP layers on the nonlinear analysis preferences and the results was presented.

• The Journal of Korean Physical Therapy
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• v.15 no.4
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• pp.412-430
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• 2003

Functional stability is dependent on integrated local and global muscle function. Movement dysfunction can present as a local and global problem, though both frequently occur together. To good understand how movement induces pain syndrome, the optimal actions and interaction of the multiple anatomic and functional systems involved in motion must be considered. Minor alterations in the precision of movement cause microtrauma and, if allowed to continue, will cause macrotrauma and pain. These alteration of the movement result in the development of compensatory movement and movement impairment. Muscle that become tight tend to pull the body segment to which they are attached, creating postural deviation. The antagonistic muscles may become weak and allow postural deviations due to lack of balanced support. Both hypertonic and inhibited muscles will cause an alteration of the distribution of pressure over the joint(s) that they cross and, thus, may not only result from muscle dysfunction, but produce joint dysfunction as well. Alteration of the shoulder posture and movement dysfunction may sometimes result in compression of neurovascular structures in the shoulder and arm. There is a clear link between reduced proprioceptive input, altered motor unit recruitment and the neurovascular compression. This report start with understanding of the impaired alignment, movement patterns and neuromuscular compression of the shoulder girdle by movement impairment to approach method of the movement dysfunction.

• Steel and Composite Structures
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• v.34 no.2
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• pp.171-188
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• 2020

The past research on cold-formed steel (CFS) flexural members have proved that rectangular hollow flanged sections perform better than conventional I-sections due to their higher torsional rigidity over the later ones. However, CFS members are vulnerable to local buckling, substantially due to their thin-walled features. The use of packing, such as firmly connected timber planks, to the flanges of conventional CFS lipped I-sections can drastically improve their flexural performance as well as structural efficiency. Whilst several CFS composites have been developed so far, only limited packing materials have been tried. This paper presents a series of tests carried out on different rectangular hollow compression flanged sections with innovative packing materials. Four-point flexural tests were carried out to assess the flexural capacity, failure modes and deformed shapes of the CFS composite beam specimens. The geometric imperfections were measured and reported. The North American Specifications and Indian Standard for cold-formed steel structures were used to compare the design strengths of the experimental specimen. The test results indicate clearly that CFS rectangular 'compression' flanged composite beams perform significantly better than the conventional rectangular hollow flanged CFS sections.

• Computers and Concrete
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• v.22 no.6
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• pp.527-538
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• 2018

Buckling of longitudinal bars is a brittle failure mechanism, often recorded in reinforced concrete (RC) structures after an earthquake. Studies in the literature highlights that it often occurs when steel is in the post elastic range, by inducing a modification of the engineered stress-strain law of steel in compression. A proper evaluation of this effect is of fundamental importance for correctly evaluating capacity and ductility of structures. Significant errors can be obtained in terms of ultimate bending moment and curvature ductility of an RC section if these effects are not accounted, as well as incorrect evaluations are achieved by non-linear static analyses. This paper presents a numerical investigation aiming to evaluate the engineered stress-strain law of reinforcing steel in compression, including second order effects. Non-linear FE analyses are performed under the assumption of local buckling. A role of key parameters is evaluated, making difference between steel with strain hardening or with perfectly plastic behaviour. Comparisons with experimental data available in the literature confirm the accuracy of the achieved results and make it possible to formulate recommendations for design purposes. Finally, comparisons are made with analytical formulations available in the literature and based on obtained results, a modification of the stress-strain law model of Dhakal and Maekawa (2002) is proposed for fitting the numerical predictions.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.3
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• pp.63-67
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• 1994

A main property for fiber reinforced thermoplastic composite material in compression molding is the flow of fibers. This flow is so effective a long direction of acting force that this study examined for the inclined angel of 30$^{\circ}$, 45$^{\circ}$ and 6$^{\circ}$. Below the near softing temperature of plastic, the fiber has been fractured at a point so that the fiber strength is smaller then the local hydrostatic stress in the mold. It has been found that the position of fracture is changing accrding to the incling angle. In case of the above softing temperature, the larger the inclined is, the farther the flow of fiber move. Also the plastic flow has been progresed with the cicular are type.

• Journal of the Korea Society of Computer and Information
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• v.24 no.6
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• pp.73-80
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• 2019

In this paper, we propose an effective dynamic range compression (DRC) method of infrared images. A histogram of infrared images has narrow dynamic range compared to visible images. Hence, it is important to apply the effective DRC algorithm for high performance of an infrared image analysis. The proposed algorithm for high dynamic range divides an infrared image into the overlapped blocks and calculates Shannon's entropy of overlapped blocks. After that, we classify each block according to the value of entropy and apply adaptive histogram modification method each overlapped block. We make an intensity mapping function through result of the adaptive histogram modification method which is using standard-deviation and maximum value of histogram of classified blocks. Lastly, in order to reduce block artifact, we apply hanning window to the overlapped blocks. In experimental result, the proposed method showed better performance of dynamic range compression compared to previous algorithms.

• Journal of Korean Association for Spatial Structures
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• v.1 no.2 s.2
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• pp.67-74
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• 2001

This paper is to estimate the load carrying capacities of concrete-filled steel tubular columns and the important parameters are selected the size, length and concrete strength. he concrete-filled tube structures has many excellent structural properties, that is, high load capacity, good plastic deformation and high resistance local buckling. Under these background, this study Investigated to the structural compression behaviors, the maximum strength, the confinement effects, the fracture mechanism, local buckling failure and concrete strength effects.

• Steel and Composite Structures
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• v.29 no.2
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• pp.151-159
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• 2018

In order to reduce the deformation and delay the local buckling of concrete filled steel tube (CFST) columns, strengthening the structures with stiffeners is an effective method. In this paper, a new stiffening method with inclined stiffeners was used to investigate the behaviors of short CFST columns under axial compression. Besides, a three-dimensional nonlinear finite element (FE) model was applied to simulate the mechanical performances, including the total deformation, local buckling, and stress-strain relationship. Revised constitutive models of stiffened steel tube and confined concrete are proposed. A good agreement was achieved between the test and FE results. Furthermore, the calculated results of load capacity by using a simplified method also show a good correlation with experimental data.

• Steel and Composite Structures
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• v.19 no.6
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• pp.1355-1367
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• 2015

Steel conical shells have long been used in various parts of different structures. Sensitivity to the initial geometrical imperfection has been one of the most significant issues on the stability of these structures, which has made them highly vulnerable to the buckling. Most attention has been devoted to structures under normal fabrication related imperfections. Notwithstanding, the challenges of large local imperfections - presented herein as dent-shaped imperfections - have not been a focus yet for these structures. This study aims to provide experimental data on the effect of such imperfections on the buckling capacity of these shells under axial compression. The results show changes in the buckling mode and the capacity for such damaged thin specimens as is outlined in this paper, with an average overall capacity reduction of 11%.