• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.5
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• pp.68-77
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• 2012

The joint of existing steel grid composite deck is composed of lap splice of reinforcing bar with end hooks and field-placed concrete. In this study, bending tests of deck joint composed of concrete shear key and high tension bolts are carried out for the design variable, concrete shear key strengthened with steel plate or not, and test results are compared with flexural performance of the existing deck joint. Test results showed that the mechanical deck joint has about 30% ~ 60% more ultimate bending strength than the existing joint. According to analysis results of moment-curvature relationship, the initial bending stiffness of the existing deck joint is some higher than that of mechanical joint. But, after crack failure the structural performance of the existing deck joint is rapidly reduced. Furthermore, the deck joint with the strengthened shear key with steel plate has more bending moment capacity than the deck joint without strengthening. And strengthening of shear key has positive influence on the increase of bending stiffness.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.1
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• pp.8-17
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• 2006

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.87-90
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• 2004

A numerical analysis was made for the unsteady flow fields of rotor system of a Tilt-Rotor aircraft in cruise mode. The Reynolds-averaged thin-layer Navier-Stokes equations were discretized by Roe's upwind differencing scheme and integrated in time by the LU-SGS algorithm. The computational domain of the rotor system was constructed by six multi-block Chimera grids. Simulated unsteady flow fields of rotating blades were studied in several different view points.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.21-24
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• 2005

Numerical analysis were made for the unsteady flow fields of the rotor system of a Tilt-Rotor aircraft in cruise mode. The Reynolds-averaged thin-layer Wavier-Stokes equations were discretized by Roe's upwind differencing scheme and integrated in time by the LU-SGS algorithm. The computational domain of the rotor system was constructed by seven multi-block Chimera grids. Comparison of pressure coefficient on the surface of the main wing and blades were made for 3cases of advance ratio(0.325, 0.350, 0.375) and thrust and power coefficients for the rotor were compared with experimental data.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.78-83
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• 2002

A modified patched grid scheme has been developed and employed for and axi-symmetric unsteady Euler solver based on Roe's FDS to analyze the unsteady flow fields induced by a train and a tunnel. On this paper, the innovative zonal method, named hybrid dimensional approach, was proposed and applied to the train-tunnel interaction problems. The basic idea of this method is to maximize the efficiency of numerical calculations by minimal assumption of spatial dimensions. The hybrid dimensional approach, embedded in the present modified patched grid method, yielded high numerical accuracy as much as the fully axe-symmetric method. The hybrid dimensional approach is expected to reduce the huge computation time of the train-tunnel interaction problems especially in the cases of solving a long tunnel.

• 한국전산유체공학회:학술대회논문집
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• 1998.05a
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• pp.55-60
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• 1998

An elliptic grid generation scheme using Laplace's equations guarantees the resulting grids to be crossing-free as a result of maximum principle in its analytic form. Numerical results, however, often show the grid lines overlapping each other or crossing the boundaries, especially for very sharp convex corners. The cause of this problem is investigated, and it is found that this problem can be handled by properly modifying the coefficients of transformed Laplace's equations in the computational domain.

• 한국전산유체공학회:학술대회논문집
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• 2006.10a
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• pp.208-208
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• 2006

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.209-211
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• 2007

The computational time of Stocahstic Diagonalization (SD) calculation for 2-dimensional interacting fermion systems is reduced by using several methods including symmetry operations. First, each lattice is subdivided into spin-up and spin-down lattices separately, thus allowing a bi-partite lattice. A valid basis state is then obtained from stacking up an up-spin configuration on top of a down-spin configuration. As a consequence, the memory space to be used in saving the trial basis state reduces significantly. Secondly, the matrix elements of a Hamiltonianin are reconrded in a look-up table when making basis state set. Thus the repeated calculation of the matrix elements of the Hamiltonian are avoided during SD process. Thirdly, by applying symmetry operations to the basis state set the original basis state is transformed to a new basis state whose elements are the eigenvectors of the symmetry operations. The ground state wavefunction is constructed from the elements of symmetric - bonding state - basis state set. As a result, the total number of basis states involved in SD calculation is reduced upto 50 percentage by using symmetry operations.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.100-110
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• 2007

A new design approach for a delicate treatment of complex geometries such as a wing/body configuration is arranged using overset mesh technique under large scale computing environment for turbulent viscous flow. Various pre- and post-processing techniques which are required of overset flow analysis and sensitivity analysis codes are discussed for design optimization problems based on gradient based optimization method (GBOM). The overset flow analysis code is validated by comparing with the experimental data of a wing/body configuration (DLR-F4) from the 1st Drag Prediction Workshop (DPW-I). In order to examine the applicability of the present design tools, careful design works for the drag minimization problem of a wing/body configuration are carried out by using the developed aerodynamic shape optimization tools for the viscous flow over multiple-body aircraft geometries.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.91-94
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• 2004

A numerical analysis was made to investigate the intensity diminution of a simple silencer for high pressure blast flow fields. Reynolds-Averaged Wavier-Stokes equations were solved for an axisymmetric computational domain constructed by multi block Chimera grids. A blast flow field without the silencer was also calculated to validate the present numerical method. The evolution of high pressure blast flow fields was observed by depicting calculated contours of pressure and Mach number. It was found that the tested silencer could achieve 76 percent intensity diminution.