• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.129-136
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• 1999

The use of strut preloading method is gradually increasing in braced excavations in Korea. And it is necessary to analyse the effects of strut preloading on the wall deflection, bending moment and strut axial force etc. In this study, by using the analysis method of beams on elasto-plastic foundations, parametric studies of correlation between preloading and earth retaining structures in sandy soils were peformed in strut preloading application. As results, about 50% of design strut load was effective as a preloading force in considering the displacement and member forces of structures. And at least the effective stiffness of strut should be over 25% of the ideal value in order to restrain the excessive increase of wall deflection and bending moments. In order to protect excessive movements in braced excavation, to preload the strut was rather effective way than to increase the stiffness of strut and braced wall, but the excessive axial force of strut should be checked simultaneously.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.20 no.5
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• pp.492-501
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• 2010

Equations of motion of thin-walled composite H-type cross-section beams incorporating a number of nonclassical effects of transverse shear and primary and secondary warping, and anisotropy of constituent materials are derived. The vibrational characteristics of a composite thin-walled beam exhibiting the circumferentially asymmetric stiffness system(CAS) and the circumferentially uniform stiffness system(CUS) are exploited in connection with the bending-transverse shear coupling and the bending-twist coupling resulting from directional properties of fiber reinforced composite materials.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1989.04a
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• pp.28-32
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• 1989

In the recent years, parallelogrammic shape structures were often introduced in the Civil Engineering. Especially parallelogrammic shape highway slabs, which were used in the portions of Interstate-75, U.S.A., were a unique one to result in only one wheel crossing the joint at any one time. In this reserch, major efforts were made to provide an appropriate subroutine program and to study an analytical behavior of paralleloqrammic plate bending element by developing the stiffness and load matrices.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.480-485
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• 2004

The applications of composite materials have increased over the past few decades in a variety of structures that require high ratio of stiffness and strength to weight ratios. Recently the thick open section composite beams are used extensively as load carrying members and stiffeners of structural elements. However, most of studies on thick composite beams are limited only to closed section beams. In this study, an open cross-section thick-walled composite beam model which includes coupled stiffness, transverse shear, and warping effects is suggested and the deflections associated with the thick-walled composite beams and thin-walled composite beams are obtained and compared with the finite element analysis results.

• Textile Coloration and Finishing
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• v.18 no.3 s.88
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• pp.23-30
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• 2006

The bending properties, wrinkle resistance, and fabric retention behaviors of cotton knitted fabrics in the wale and course directions were studied for their dependence upon resin finishing, knit structure, and washing cycles. Stiffness, wrinkle recovery angles, and dimensional stability were investigated before and after resin finishing and laundering. It has been found that any change in the physical properties of the knitted fabrics with respect to knit structure and fabric directions are related to accompanying modifications to the state of the fiber properties. The decrease of fabric shrinkage rates and wrinkle recovery properties from increasing laundering cycles is related with resin incorporated on the fiber surface. This study shows that resin finishing on knitted fabrics can be performed only to improve fabric retention properties with reduced wrinkle recovery properties.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.396-400
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• 2006

We studied the influences of open cracks in free vibrating beam with rectangular section using a numerical model. The crack was assumed to be single and always open during the free vibration and equivalent bending stiffness of a cracked beam was calculated based on the strain energy balance. By Galerkin's method, the frequencies of cantilever beam could he obtained with respect to various crack depths and locations. Also, the experiments on the cracked beams were carried out to find natural frequencies. The cracks were initiated at five locations and the crack depths were increased by five steps at each location. The experimental results were compared with the numerical results and the comparison results were discussed.

• Computers and Concrete
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• v.10 no.5
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• pp.489-505
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• 2012

This paper presents a simplified grid beam model for simulating the nonlinear response of reinforced concrete flat-plate structures. The beam elements are defined with nonlinear behavior for bending moment and torsion. The flexural stiffness and torsional strength of the beam elements are defined based on experimental data to implicitly account for slab two-way bending effects. A failure criterion that considers the interaction between the punching strength and slab flexural behavior is incorporated in the model. The effects of bond-slip of slab reinforcement on connection stiffness are examined. The proposed grid beam model is validated by simulating large-scale tests of slab-column connections subjected to concentric gravity loading and unbalanced moment. This study also determines the critical parameters for a hysteretic model used to simulate flat-plates subjected to cyclic lateral loading.

• Advanced Composite Materials
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• v.18 no.2
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• pp.105-119
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• 2009

In this work, the structural response of thin-walled composite beams with pretwist angle is investigated by using a mixed beam approach that combines the stiffness and flexibility methods in a unified manner. The Reissner's semi-complimentary energy functional is used to derive the stiffness matrix that approximates the beam in an Euler-Bernoulli level for extension and bending and Vlasov level for torsion. The bending and torsion-related warpings induced by the pretwist effects are derived in a closed form. The developed theory is validated with available literature and detailed finite element structural analysis results using the MSC/NASTRAN. Pretwisted composite beams with rectangular solid and thin-walled box sections are illustrated to validate the current approach. Acceptable correlation has been achieved for cases considered in this study. The effects of pretwist and fiber orientation angles on the static behavior of pretwisted composite beams are also studied.

• Textile Coloration and Finishing
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• v.7 no.1
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• pp.58-64
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• 1995

In this study, we attempted to expect the mechanical characteristics of the wool fabrics by knowing the yarns. Moreover, we believe that we could apply these results to fabric design. We investigated the relationship between the mechanical characteristics of yarns and fabrics. As results, we have found that bending rigidity, bending hysteresis, compressional energy and compressional linearity between yarns and fabrics had correlated more than r=0.5. Also, the correlation between regression and experimental values is r=0.5 in stiffness while it is r=0.67 in fullness. And regression values were larger than experimental ones in stiffness, but were not in fullness. The correlation between regressional and experimental values had 0.63 in THV. According to the study, it is possible to apply it to fabric design when our predicting the primary hand and the total hand values of the fabrics from the mechanical characteristics of the yarns.

• Structural Engineering and Mechanics
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• v.26 no.1
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• pp.69-86
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• 2007

A four-noded plate bending quadrilateral (PBQ4) and an eight-noded plate bending quadrilateral (PBQ8) element based on Mindlin plate theory have been adopted for modeling the thick plates on elastic foundations using Winkler model. Transverse shear deformations have been included, and the stiffness matrices of the plate elements and the Winkler foundation stiffness matrices are developed using Finite Element Method based on thick plate theory. A computer program is coded for this purpose. Various loading and boundary conditions are considered, and examples from the literature are solved for comparison. Shear locking problem in the PBQ4 element is observed for small value of subgrade reaction and plate thickness. It is noted that prevention of shear locking problem in the analysis of the thin plate is generally possible by using element PBQ8. It can be concluded that, the element PBQ8 is more effective and reliable than element PBQ4 for solving problems of thin and thick plates on elastic foundations.