• Water Engineering Research
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• v.1 no.2
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• pp.159-168
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• 2000

In this paper, the increment of the local scour depth at piers by constructing the bridge between existing bridges is examined through the experiments in which 5 piers in the non-cohesive bed material in the experimental flume were installed. In the experiments the maximum distance of 25 times of the pier length and the maximum distortion width of 8 times of the pier width were utilized. Through the experimental studies, it was indicated that low flow, which can be characterized as the flow having low Froude numbers, the maximum bed configuration change is obtained when the piers are installed in the straight line in the flor direction without any distortion. However, In the high flow, which can be characterized as the flow having high Froude numbers, the maximum bed configuration change is obtained when the piers are installed with some distortion from the flow direction. The influence of the bed configuration by interaction between bridge piers is changed depending upon the Froude numbers, the distance between piers, and the distortion width between adjacent bridge piers. Also, because the scour patterns are affected by the bed configuration, the maximum scour should be increased by about 60% compared to that in a single pier if the interaction between bridge piers exists. It can be suggested that the maximum scour depth at bridge piers predicted by applying the existing equations should be increased if the interaction between bridge piers exist. Those cases are found when new bridges are constructed successively in the river in the urban area.

• Steel and Composite Structures
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• v.8 no.2
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• pp.145-158
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• 2008

In slender sections there is a substantial post-buckling strength provided after the formation of local buckling waves. These waves happened due to normal stresses or shear stresses or both. In this study, a numerical investigation of the behavior of slender I-section beams in combined pure bending and shear has been described. The studied cases were assumed to be prevented from lateral torsional buckling. To achieve this aim, a finite element model that simulates the geometric and material nonlinear nature of the problem has been developed. Moreover, the initial geometric imperfections were included in the model. Different flange and web width-thickness ratios as well as web panel aspect ratios have been considered to draw complete set of interaction diagrams. Results reflect the interaction behavior between flange and web in resisting the combined action of moments and shear. In addition, the web panel aspect ratio will not significantly affect the combined ultimate shear-bending strength as well as the post local buckling strength gained by the section. Results are compared with that predicted by both the Eurocode 3 and the American Iron and Steel specifications, AISI-2001. Finally, an empirical interaction equation has been proposed.

• Structural Engineering and Mechanics
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• v.41 no.4
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• pp.559-573
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• 2012

An adaptive modeling and simulation technique is introduced for the effective and reliable fluid-structure interaction analysis using MSC/Dytran for large-scale complex pressurized liquid containment. The proposed method is composed of a series of the global rigid sloshing analysis and the locally detailed fluid-structure analysis. The critical time at which the system exhibits the severe liquid sloshing response is sought through the former analysis, while the fluid-structure interaction in the local region of interest at the critical time is analyzed by the latter analysis. Differing from the global coarse model, the local fine model considers not only the complex geometry and flexibility of structure but the effect of internal pressure. The locally detailed FSI problem is solved in terms of multi-material volume fractions and the flow and pressure fields obtained by the global analysis at the critical time are specified as the initial conditions. An in-house program for mapping the global analysis results onto the fine-scale local FSI model is developed. The validity and effectiveness of the proposed method are verified through an illustrative numerical experiment.

• Coupled systems mechanics
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• v.1 no.3
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• pp.269-283
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• 2012

In the present paper, a multilevel approach for the local nanobuckling analysis of carbon nanotube (CNT) based composite materials is proposed and described. The approach comprises four levels, all of them at nanoscale. The first level aims to propose the potential that describes the interatomic forces between carbon atoms. In the second level, molecular dynamics simulations are performed to extract the elastic properties of the CNT. The third level aims to determine the stiffness of the material that surrounds the CNT (matrix), using the annular membrane analysis. In the fourth level, finite strip analysis of the CNT elastically restrained by the matrix is performed to calculate the critical strain at which the CNT buckles locally. In order to achieve accurate results and take the CNT-matrix interaction into account, the $3^{rd}$ and $4^{th}$ steps may be repeated iteratively until convergence is achieved. The proposed multilevel approach is applied to several CNTs embedded in a cylindrical representative volume element and illustrated in detail. It shows that (i) the interaction between the CNT and the matrix should be taken into account and (ii) the buckling at nanoscale is sensitive to several types of local buckling modes.

• Interaction and multiscale mechanics
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• v.5 no.2
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• pp.91-104
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• 2012

There is relatively little numerical study on the behavior of eccentrically loaded high strength rectangular concrete-filled steel tubular (CFST) slender beam-columns with large depth-to-thickness ratios, which may undergo local and global buckling. This paper presents a multiscale numerical model for simulating the interaction local and global buckling behavior of high strength thin-walled rectangular CFST slender beam-columns under eccentric loading. The effects of progressive local buckling are taken into account in the mesoscale model based on fiber element formulations. Computational algorithms based on the M$\ddot{u}$ller's method are developed to obtain complete load-deflection responses of CFST slender beam-columns at the macroscale level. Performance indices are proposed to quantify the performance of CFST slender beam-columns. The accuracy of the multiscale numerical model is examined by comparisons of computer solutions with existing experimental results. The numerical model is utilized to investigate the effects of concrete compressive strength, depth-to-thickness ratio, loading eccentricity ratio and column slenderness ratio on the performance indices. The multiscale numerical model is shown to be accurate and efficient for predicting the interaction buckling behavior of high strength thin-walled CFST slender beam-columns.

• Journal of the Korean Physical Society
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• v.73 no.11
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• pp.1691-1697
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• 2018

Employing the density functional theory, we have investigated the roles of Coulomb and Hund's interactions in the electronic and magnetic properties of newly discovered ${\alpha}-RuCl_3$ having the $R{\overline{3}}$ symmetry, which is in close proximity of the Kitaev system. We show that both the size and the direction of local magnetic moment are highly dependent on Coulomb and Hund's interactions, and the spin and orbital parts show different behaviors. The validity of the so-called $j^{eff}$ picture is accessed upon interaction parameters, and the explicit roles of Hund's interaction in the local electronic structures and magnetic properties are discussed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.27 no.2
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• pp.120-124
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• 1991

An interaction of turbulent boundary layer and local roughness effects was evaluated to investigate the shear frictional coefficient in diffuser. Clauser roughness function was applied to Karman's integral equation for governing equation. The roughness of overall and local diffuser surfaces were calculated using Cole's wall and wake law and Clauser's roughness function for turbulent boundary layer characteristics. The calculating results were compared with the experimental results of other paper. It shows some significant improyements for shear frictional coefficient. Computer code was then used to confirm the behavior of local frictional coefficient along with diffuser roughness surface for some reduction of shear flow stress.

• Korean Journal of Organic Agriculture
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• v.26 no.1
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• pp.73-82
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• 2018

The alternative marketing can be defined a face to face regional marketing that commodities are traded based on mutual trust and understanding which have been accumulated through relationships formation and interaction between producers and consumers. Essences of an alternative marketing are formation, expansion and solidarity of relationships between producers and consumers, mutual trust and communication, and cooperation. Based on these, it makes it's principle to trade regionally and shorten food mileage and psycho-social distance. For example, there are local food direct stores, local food markets, farmer's markets, food package sales, CSA, local food school or public meal and so on. In alternative marketing, the relationship among them is especially considered very important in marketing process, not just a flow of commodities.

• Publications of The Korean Astronomical Society
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• v.30 no.2
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• pp.451-452
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• 2015

We performed statistical analysis for a nearby (0.01 < z < 0.05) volume limited ($M_r$ < -19) sample of galaxies via visual inspection and the definition of galaxy pair systems based on the Sloan Digital Sky Survey Data Release 7 in order to confirm the effects of galaxy interaction on AGN activities. We found that local environmental effects such as galaxy interaction have an influence on the enhancement of the frequency and the strength of the AGN activity. This article is the summary of the paper which will be submitted soon.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.99.1-99.1
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• 2012

We report the results of our analysis of far ultraviolet (FUV) observations made for the broad region around the ${\alpha}$ Vir (Spica) including the interaction zone of the Loop I and the Local Bubble. We employed the datasets of the GALEX and the FIMS, which made observations at similar FUV wavelengths. First, we noted that the GALEX image was enhanced in the southern region where the interaction zone exists. We attribute this enhanced FUV emission to dust scattering of the stellar photons, mostly from the background field stars with small contributions from the central star Spica. While the region is optically thin in general, the FUV intensity did not correlate well with the dust extinction level, indicating that the local radiation field has significant fluctuations. On the other hand, the GALEX FUV intensity well with the $H{\alpha}$ intensity as well as the dust extinction level in the northern part. In fact, the neutral hydrogen column density correlated very well with the dust extinction level throughout the whole region in consideration. The relationship between the neutral hydrogen column density and the color excess was estimated to be ${\sim}7{\times}10^{21}atoms\;cm^{-2}$, which is a little higher than the previous observations made for a diffuse interstellar medium. The spectral analyses of the FIMS observations showed the enhanced C IV emission throughout the whole region, indicating that the C IV emission arises by the interaction of the hot gases with the shell boundaries. A simple model showed that a large portion of the C IV emission comes from the Loop I side of the interaction zone, compared to the Local Bubble side. The FIMS spectrum also showed indications of the molecular hydrogen fluorescence lines for the interaction zone.