• Journal of the Korean Wood Science and Technology
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• v.16 no.1
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• pp.45-54
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• 1988

This study was carried out to investigate the fiber length, fiber width and fiber thickness on the longitudinal direction by the parts of culm and also specific gravity in air dry, dyna.mic mechanical properties and internal frictions by the internode and the node in Phyllostachys bambusoides Phyllostachys nigra var. henonis and Phllostachys edulis which were grown in Korea. The results obtained were as follows; 1. The variations of fiber length and fiber width on the longitudinal direction had a tendency to increase slightly from the butt and then to decrease toward the top. but there was not a definite variation for fiber thickness according to the parts of culm. 2. The specific gravity in air dry of internode was increased from the butt toward the top, but the specific gravity in air dry of node was not correlations with the parts of culm. 3. Dynamic Young's modulus of internode on the longitudinal direction was increased according to the heights of culms within each species, and there were in order of P. edulis P. nigra var. henonis and P. bambusoides. 4. Correation coefficients between the specific gravity and the dynamic Young's modulus were 0.837 in P. bambusoides 0.871 in P. nigra var. henonis and 0.935 in P. edulis and there was also highly significant for dynamic Young's modulus between the specific gravities in air dry. 5. There were not correlations between the internal frictions and the parts of internode.

• Structural Engineering and Mechanics
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• v.51 no.6
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• pp.1067-1089
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• 2014

In this paper, three dimensional static and dynamic analyses of two dimensional functionally graded annular sector plates have been investigated. The material properties vary through both the radial and axial directions continuously. Graded finite element and Newmark direct integration methods have been used to solve the 3D-elasticity equations in time and space domains. The effects of power law exponents and different boundary conditions on the behavior of FGM annular sector plate have been investigated. Results show that using 2D-FGMs and graded elements have superiority over the homogenous elements and 1D-FGMs. The model has been compared with the result of a 1D-FGM annular sector plate and it shows good agreement.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.107-112
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• 2003

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions such as high impact loading are required to provide appropriate safety assessment to varying dynamically loaded mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material behavior under high strain rate loading conditions. In this paper, the dynamic deformation behavior of a brass under both high strain rate compressive loading conditions has been determined using the SHPB technique.

• Fibers and Polymers
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• v.6 no.4
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• pp.284-288
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• 2005

Poly(ethylene terephthalate) was annealed at different temperature and pressure of supercritical carbon dioxide $(CO_2)$ using samples quenched from the melt. Crystallization and molecular relaxation behavior due to $CO_2-annealing$ of samples were investigated using differential scanning calorimetric and dynamic mechanical measurements. The glass transition and crystallization temperatures significantly decreased with increasing temperature and pressure of $CO_2$. The dynamic mechanical measurement of samples annealed at $150^{\circ}C$ in supercritical $CO_2$ showed three relaxation peaks, corresponding to existence of different amorphous regimes such as rigid, intermediate, and mobile domains. As a result, the mobile chains were likely to facilitate crystallization in supercritical state. It also led to the decreased modulus of $CO_2-annealed$ samples with increasing pressure.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.11
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• pp.3649-3654
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• 1996

A transient hydraulic flow rate computation scheme is described here so that the transient hydraulic flow rate can be determined using the dynamic pressure measurements at the ends of a straight flow line with a dynamic model of the hydraulic line. This method can be applied to determine the orifice ares of high response valve. Simulation results indicate that the method is relatively robust to realistic levels of uncertainties in the fluid properties.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.268-273
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• 2000

Mechanical properties of the materials used for transportations and industrial machinery under high strain rate loading conditions are required to provide appropriate safety assessment to these mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique, a special experimental apparatus, can be used to obtain the material behavior under high strain rate loading condition. In this paper, dynamic deformation behaviors of the aluminum alloys, Al2024-T4, Al6061-T6 and Al7075-T6, under high strain rate compressive and tensile loading are determined using SHPB technique.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.19-24
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• 2001

In this study, Pb(La Ce)$TiO_3$ composition ceramics were manufactured for 20 MHz resonator application. Electromechanical coupling factor, mechanical quality factor and dynamic range of thickness vibration mode were measured as the variations of L/T(length/thickness) ratio of ceramic substrats. Mechanical quality factor and dynamic range of third overtone thickness vibration mode showed the highest value of 2,773 and 52.22 dB at specimen S4(l/t=12), respectively. The excellent temperature stability of resonant frequency suitable for resonator application was shown, regardless of thermal shock.

• Structural Engineering and Mechanics
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• v.55 no.2
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• pp.263-280
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• 2015

This paper describes a study of the collision of hard steel spheres against aluminium thin circular plates at speeds up to 140 m/s. The tests were monitored by a high speed camera and a chronoscope, which allowed the determination of the ballistic limit and the plate deformation pattern. Quasi-static material parameters were obtained from tests on a universal testing machine and dynamic mechanical characterization of two aluminium alloys were conducted in a split Hopkinson pressure bar. Using a damage model, the perforation of the plates was simulated by finite element analysis. Axisymmetric, shell and solid elements were employed with various parameters of the numerical analysis being thoroughly discussed, in special, the dynamic model parameters. A good agreement between experiments and the numerical analysis was obtained.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1225-1232
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• 1996

In this paper the vibration and power flow analysis for the branched piping system conveying fluid are performed by wave approach. The uniform straight pipe element conveying fluid is formulated using the dynamic stiffness matrix by wave approach. The branched piping system conveying fluid can be easily formulated with considering of simple assumptions of displacements at the junction and continuity conditions of the pipe internal flow. The dynamic stiffness matrix for each uniform straight pipe element can be assembled by using the global assembly technique using in conventional finite element method. The computational method proposed in this paper can easily calculate the forced responses and power flow of the branched piping system conveying fluid regardless of finite element size and modal properties.

• Steel and Composite Structures
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• v.10 no.2
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• pp.151-168
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• 2010

The subject of the paper is an isotropic metal foam rectangular plate. Mechanical properties of metal foam vary continuously through plate of the thickness. A nonlinear hypothesis of deformation of plane cross section is formulated. The system of partial differential equations of the plate motion is derived on the basis of the Hamilton's principle. The system of equations is analytically solved by the Bubnov-Galerkin method. Numerical investigations of dynamic stability for family rectangular plates with respect analytical solution are performed. Moreover, FEM analysis and theirs comparison with results of numerical-analytical calculations are presented in figures.