• Steel and Composite Structures
• /
• v.35 no.3
• /
• pp.405-413
• /
• 2020

Current study on the buckling analysis of steel plate in composite structures normally focuses on applying finite element method to derive the buckling stress. However, it is time consuming, computationally complicated and tedious for general use in design by civil engineers. Therefore, in this study an analytical study is conducted to predict the buckling behavior of steel plates in composite structures. Hand calculation method was proposed based on energy principle. Novel buckling shapes with biquadratic functions along both loaded and unloaded direction were proposed to satisfy the boundary condition. Explicit solutions for predicting the critical local buckling stress of steel plate is obtained based on the Rayleigh-Ritz approach. The obtained results are compared with both experimental and numerical data. Good agreement has been achieved. Furthermore, the influences of key factors such as aspect ratio, width to thickness ratio, and elastic restraint stiffness on the local buckling performance are comprehensively discussed.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.43 no.6 s.312
• /
• pp.57-64
• /
• 2006

Motion estimation plays an important role for the compression of video signals. The proposed method utilizes an adaptive threshold and characteristics of a distribution of SAD (sum of absolute difference). Generally, the more complex the SAD distribution is, the larger SAD value tends to be. This proposed algorithm tries to reduce the search points in a simple distribution but increase them in a complex distribution to avoid local minima. A macro block is divided into 9 areas. One of them chosen using spatio-temporal correlation is called the primary area and the others are called the secondary area that will be searched to avoid local minima. The proposed algorithm decides if just one area (the primary area or the secondary area) will be enough to be searched or both areas should be searched, using adaptive threshold. Compared with famous motion estimation algorithms, the simulation result shows that the searching points per macro block and MSE decreases about 16.4% and 32.83 respectively on the average.

• Steel and Composite Structures
• /
• v.17 no.4
• /
• pp.497-516
• /
• 2014

The ultimate carrying capacity of axially loaded welded square box section members made of medium and high strength steels (nominal yield stresses varying from 345 MPa to 460 MPa), with large width-to-thickness ratios ranging from 35 to 70, is analyzed by finite element method (FEM). At the same time, the numerical results are compared with the predicted results using Direct Strength Method (DSM), modified DSM and Effective Yield Strength Method (EYSM). It shows that curve a, rather than curve b recommended in Code for design of steel structures GB50017-2003, should be used to check the local-overall interaction buckling strength of welded square section columns fabricated from medium and high strength steels when using DSM, modified DSM and EYSM. Despite all this, EYSM is conservative. Compared to EYSM and modified DSM, DSM provides a better prediction of the ultimate capacities of welded square box compression members with large width-thickness ratios over a wide range of width-thickness ratios, slenderness ratios and steel grades. However, for high strength steels (nominal yield strength greater than 460 MPa), the numerical and existent experimental results indicate that DSM overestimates the load-carrying capacities of the columns with width-thickness ratio smaller than 45 and slenderness ratio less than 80. Further, for the purpose of making it suitable for a wider scope, DSM has been modified (called proposed modified DSM). The proposed modified DSM is in excellent agreement with the numerical and existing experimental results.

• Steel and Composite Structures
• /
• v.34 no.1
• /
• pp.1-15
• /
• 2020

This paper presents experimental and numerical studies on effects of local damages on the in-plane elastic-plastic buckling and strength of a fixed parabolic steel tubular arch under a vertical load distributed uniformly over its span, which have not been reported in the literature hitherto. The in-plane structural behaviour and strength of ten specimens with different local damages are investigated experimentally. A finite element (FE) model for damaged steel tubular arches is established and is validated by the test results. The FE model is then used to conduct parametric studies on effects of the damage location, depth and length on the strength of steel arches. The experimental results and FE parametric studies show that effects of damages at the arch end on the strength of the arch are more significant than those of damages at other locations of the arch, and that effects of the damage depth on the strength of arches are most significant among those of the damage length. It is also found that the failure modes of a damaged steel tubular arch are much related to its initial geometric imperfections. The experimental results and extensive FE results show that when the effective cross-section considering local damages is used in calculating the modified slenderness of arches, the column bucking curve b in GB50017 or Eurocode3 can be used for assessing the remaining in-plane strength of locally damaged parabolic steel tubular arches under uniform compression. Furthermore, a useful interaction equation for assessing the remaining in-plane strength of damaged steel tubular arches that are subjected to the combined bending and axial compression is also proposed based on the validated FE models. It is shown that the proposed interaction equation can provide lower bound assessments for the remaining strength of damaged arches under in-plane general loading.

• The korean journal of orthodontics
• /
• v.26 no.5 s.58
• /
• pp.581-590
• /
• 1996

Bone resorptiion was predominate in compression site, bone formation in tension site of periodontal ligament during tooth movement. The biologic response at compressiion site was different from tension site. Thus the CGHP immuno-positive nerve fiber will respond differently to mechanical force according to the area( compression or tension site). The purpose of this study was to investigate this response of CGRP immune-positive nerve fiber in the periodontal ligament according to the duration of applied force and the area (compression or tension site) during experimental tooth movement. The experimental animals were 7 week old male rat (approximately 200 gm). The orthodontic force was applied mesially to the right maxillary molar using the Ni-Ti coil spring during 12hours, 1, 3, 7, and 120days. Immunohistochemical staining using antibody against CGRP was performed after sacrifice. The results were as follows. The CGRP immune-positive nerve bundle showed reduced immunoreactivity and nerve fibers reduced in density after application of orthodontic force for 12 hours and 1day. The CGRP immune-positive nerve fibers showed many thin branches at the apical periodontal ligament after application of force for 3 days as compared with normal. The tension site in the apical periodontal ligament showed more branches than the compression site. In 7 day group, the CGRP immune-positive nerve fibers increased in terms of the number and had many thin branches in the apical periodontal ligament. The tension site had more branches than the compression site. In 12 day group, the CGRP immune-positive nerve fibers showed similar distribution to normal control at compression site of apical periodontal ligament, but the fibers at the tension site increased in number. The CGRP immuno-positive nerve fibers showed more increased at tension site than compression site after application of orthodontic force. Therefore it seems to have some relation to the bone remodeling besides the local inflammatory process.

• Korean journal of communication and information
• /
• v.34
• /
• pp.275-305
• /
• 2006

The main research question of this paper is as follows: How can broadcasting both cause the crisis in democratic participation and yet also offer the solution? The contradiction in broadcast localism has never been adequately resolved in spite of regulation at all in practice, in that localism simply cannot account for the diversity of modern life and for the external forces that incorporate local communities into much larger economic and communications network. The concept of locality in local television, however, has been multiplied and enlarged in order to adjust to "time-space compression". Recently the local television have been "interface" combining and negotiating the globalization of media market and the decentralization of political power, the economies of scale and the activation of local democracy, consequently aiming at the horizontal-cooperative network instead of old vertical-dependent one.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.13 no.5
• /
• pp.61-71
• /
• 2009

This paper presents the results of an experiment comparing the current circular CFT columns and circular CFT columns that were additionally confined by carbon fiber sheets (CFS) under axial loading. The main experimental parameters are the numbers of CFS layers and the diameter-to-thickness ratio. 10 specimens were prepared according to the experimental parameter plans, and axial compression tests were conducted. From the tests, the failure procedure, load-axial deformation curve, maximum axial strength, and deformation capacity of the CFT columns and confined CFT columns were compared. The test results showed that the maximum axial strengths of CFT columns additionally confined by CFS are increased higher than those of the current CFT columns, and that local buckling can be delayed due to the confinement effect of CFS.

• Steel and Composite Structures
• /
• v.25 no.3
• /
• pp.299-314
• /
• 2017

The aim of this paper is to investigate the performance of Lightweight Aggregate Concrete Filled Steel Tube (LWCFST) columns experimentally and compare to the behavior of Self-Compacted Concrete Filled Steel Tube (SCCFST) columns under axial loading. Four different L/D ratios and three D/t ratios were used in the experimental program to delve into the compression behaviours. Compressive strength of the LWC and SCC are 33.47 MPa and 39.71 MPa, respectively. Compressive loading versus end shortening curves and the failure mode of sixteen specimens were compared and discussed. The design specification formulations of AIJ 2001, AISC 360-16, and EC4 were also assessed against test results to underline the performance of specification methods in predicting the compression capacity of LWCFST and SCCFST columns. Based on the behaviour of the SCCFST columns, LWCFST columns exhibited different performances, especially in ductility and failure mode. The nature of the utilized lightweight aggregate led to local buckling mode to be dominant in LWCFST columns, even the long LWCFST specimens suffered from this behaviour. While with the SCCFST specimens the global buckling governed the failure mode of long specimens without any loss in capacity. Considering a wide range of column geometries (short, medium and long columns), this paper extends the current knowledge in composite construction by examining the potential of two promising and innovative structural concrete types in CFST applications.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2002.03a
• /
• pp.111-118
• /
• 2002

Recent study of soft clay of Nakdong-River basin has been taken correlation between soil properties by regression analysis without distribution whether the sample is disturbed or not, or treated as a whole area without proposing local correlation equation to Jang-U or Dae-Joe which has a specific locality. Accordingly, Those tendency cause the reliability of correlation between compression index and void ratio low and then design underestimate and uncertain eventually. In this study, Distributing the soft clay of Nakdong-River basin with failure strain of 6%, the suggestion by Skempton(1957), TakeNaka(1966)-the more sample is undisturbed, the more the ratio of E$\_$50/ and ｑ$\_$u/, ${\alpha}$ = E$\_$50//(q$\_$u//2) = 1/$\varepsilon$$\_$50/ is high-is satisfied with the value of which ${\alpha}$ is 50 and It could be taken enough data in the condition of domestic. Besides other indices also make the distribution suitable. In conclusion, This study is supposed to propose the locally subdivided regression equation between compression index and void ratio considering the sample disturbance.

• Journal of Communications and Networks
• /
• v.14 no.1
• /
• pp.21-26
• /
• 2012

As electrocardiogram (ECG) signals are generally sampled with a frequency of over 200 Hz, a method to compress diagnostic information without losing data is required to store and transmit them efficiently on a wireless personal area network (WPAN). In this paper, an ECG signal compression method for communications onWPAN, which uses feature points based on curvature, is proposed. The feature points of P, Q, R, S, and T waves, which are critical components of the ECG signal, have large curvature values compared to other vertexes. Thus, these vertexes were extracted with the proposed method, which uses local extrema of curvatures. Furthermore, in order to minimize reconstruction errors of the ECG signal, extra vertexes were added according to the iterative vertex selectionmethod. Through the experimental results on the ECG signals from Massachusetts Institute of Technology-Beth Israel hospital arrhythmia database, it was concluded that the vertexes selected by the proposed method preserved all feature points of the ECG signals. In addition, it was more efficient than the amplitude zone time epoch coding method.