• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.1
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• pp.70-76
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• 2008

Periodic cellular metals (PCMs) are actively being investigated because of their excellent specific strength and stiffness, and multi-functionality such as a heat disperse structure bearing external loading. The Kagome truss PCM has been proved that it has higher resistance to plastic buckling and lower anisotropy than other truss PCMs. In this paper, the out-of-plane compressive responses of the WBK specimens have been measured, theoretically predicted and numerically analyzed. Three specimens of two-layered WBK are fabricated and tested for measuring the responses. The peak stress of compressive behavior and effective elastic modulus are predicted based on the equilibrium equation and elastic energy conservation. Moreover, the structure of the specimen is modeled using the commercial mesh generation code, PATRAN and the finite element analysis for the model under the compression is carried out using the commercial FE code, ABAQUS. Finally, the obtained results are compared with each other to analyze the compressive characteristics of Wire-woven Bulk Kagome (WBK).

• Geomechanics and Engineering
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• v.13 no.6
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• pp.1027-1044
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• 2017

Membrane penetration is the most important factor influencing the measurement of volume change for triaxial consolidated-drained shear test for coarse-grained soil. The effective pressure p, average particle size $d_{50}$, thickness $t_m$ and elastic modulus $E_m$ of membrane, contact area between membrane and soil $A_m$ as well as the initial void ratio e are the major factors influencing membrane penetration. According to the membrane deformation model given by Kramer and Sivaneswaran, an analytical solution of the membrane penetration considering the initial void ratio is deduced using the energy conservation law. The basic equations from theory of plates and shells and the elastic mechanics are employed during the derivation. To verify the presented solution, isotropic consolidation tests of a coarse-grained soil are performed by using the method of embedding different diameter of iron rods in the triaxial samples, and volume changes due to membrane penetration are obtained. The predictions from presented solution and previous analytical solutions are compared with the test results. It is found that the prediction from presented analytical solution agrees well with the test results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.11
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• pp.2297-2304
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• 2002

Two-dimensional and three-dimensional finite element methods have been used to analyze the deformation behavior of a shadow mask due to thermal and tension load. The shadow mask inside the Braun tube of a TV set has numerous slits through which the electron beams are guided to land on the designed phosphor of red, green or blue. Its thermal deformation therefore causes landing shift of the electron beam and results in decolorization of a screen. For the realistic finite element analysis, the effective thermal conductivity and the effective elastic modulus arc calculated, and then the shadow mask is modeled as shell without slits. Next a transient thermal analysis of the shadow mask is performed, wherein thermal radiation is a major heat transfer mechanism. Analysis of the resulting thermal deformation is followed, from which the landing shift of the electron beam is obtained. The present finite element scheme may be efficiently used to reduce thermal deformation of a shadow mask and in developing prototypes of a large screen flat TV.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.73-80
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• 2010

Wind-induced vibration is one of the important structural design factors for serviceability of tall buildings. In order to evaluate the reliable wind-loads and wind induced-vibration, it is necessary to obtain the exact natural period of buildings. The discrepancy in the natural period estimation often results in the overestimation of wind loads. In this study, the effectiveness of lateral stiffness estimation method for tall buildings with flat plate system is evaluated. For this purposed, the results of finite element analysis of three recently constructed buildings are compared with those obtained from field measurement. For the analysis, factors affecting on the lateral resistance such as cracked stiffness of vertical members, elastic modulus of concrete, effective slab width, and cracked stiffness of link beam are considered. Form the results, it is found that the use of non-cracked stiffness and application of dynamic modulus of elasticity rather than initial secant modulus yields closer analysis result to the as-built period.

• Aerospace Engineering and Technology
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• v.4 no.1
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• pp.108-113
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• 2005

Strucutral and hygrothermal analysis for a composite tube is carried out in this study, that provides critical parameters for the design of a highly dimensionally stable space telescope. Carpet plots for laminate effective engineering constants are generated and used for the best tube lay-ups with high elastic modulus and highly insensitive to thermal and moisture expansion, which is essential for maintaining optical alignment of opto-mechanical system under random force applied during a launch campaign and orbital thermal load. Despace in the longitudinal direction under hygrothermal load of the tubes constructed with the selected lay-ups is calculated for the validation of lay-up designs on the dimensionalstability. Dynamic analysis is also carried out to feature the resonant behaviour. A zig-zag triangular element accurately representing through thickness stress variations for laminated structures is developed in this study and incorporated into the structural and hygrothermal analysis.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.325-332
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• 2003

In general, soil characteristics are estimated through the sample gathered by field boring without considering sample disturbance. However, soil characteristics must be changed by the degree of sample disturbance. Therefore it be need to estimate the soil characteristic considering sample disturbance which can be occurred by the change of stress condition, sampling technique and handling method. On this study, we analyzed the sample disturbance by using the methods of volume change, residual effective stress, elastic modulus and the curve of consolidation tests. In order to estimate the relationship between sample disturbance and soil characteristics, we used the piston sample and the block sample. As the results, it should be considered in design that the disturbance of the block sample, which affects the strength and compression properties of clay, is smaller than the disturbance of piston sample.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.233-238
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• 2002

In this paper, the characteristics of fresh and hardened recycled concrete were experimentally compared to investigate the applicability of the recycled fine aggregates with the substitution ratio. Test results show that the workability of the recycled concrete decreases with the increment of substitution ratio of the recycled fine aggregates except for type-D case which has a lower absorption ratio. Also air content was increased with increasing substitution ratio. It was found that the compressive strength and elastic modulus of recycled concrete were decreased with increasing substitution ratio of the recycled fine aggregates. And, the superplasticizer was more effective on the workability recovery of the recycled concrete.

• Smart Structures and Systems
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• v.21 no.4
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• pp.469-477
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• 2018

This paper presents a numerical solution for the thick cylinders made of functionally graded materials (FGMs) with a constant Poisson's ratio and an arbitrary Young's modulus. We define two fundamental solutions which are derived from an ordinary differential equation under two particular initial boundary conditions. In addition, for the single layer case, we can define the transfer matrix N. The matrix gives a relation between the values of stress and displacement at the interior and exterior points. By using the assumed boundary condition and the transfer matrix, we can obtain the final solution. The transfer matrix method also provides an effective way for the solution of multiply layered cylinder. Finally, a lot of numerical examples are present.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.8
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• pp.2123-2138
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• 1994

A study on the dynamic mechanical properties of the high strength carbon fiber epoxy composite beam was carried out. The macromechanical model was used for the theoretical analysis of the symmetric laminated composite beam. The anisotropic plate theory and Bernoulli-Euler beam theory were used to predict the effective flexural elastic modulus and the specific damping capacity of laminated composite beam. The free flexural vibration and torsional vibration tests were carried out to determine the specific damping capacities of the unidirectional laminated composite beam. The vibration tests were performed in a vacuum chamber with laser vibrometer system and electromagnetic hammer to obtain accurate experimental data. From the computational and experimental results, it was found that the theoretical values with the macromechanical analysis and the experimental data of symmetric laminated composite beam were in good agreement.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.656-661
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• 2005

An optimization formulation of unconstrained damping treatment on beams is proposed to minimize vibration responses using a numerical search method. The fractional derivative model is combined with RUK's equivalent stiffness approach in order to represent nonlinearity of complex modulus of damping materials with frequency and temperature. The loss factors of partially covered unconstrained beam are calculated by the modal strain energy method. Vibration responses are calculated by using the modal superposition method, and of which design sensitivity formula with respect to damping layout is derived analytically. Plugging the sensitivity formula into optimization software, we can determine optimally damping treatment region that gives minimum forced response under a given boundary condition. A numerical example shows that the proposed method is very effective in minimizing vibration responses with unconstrained damping layer treatment.