• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.86-89
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the resent work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section exclusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• Proceeding of EDISON Challenge
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• 2017.03a
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• pp.304-310
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• 2017

In this paper, various webs of I-shaped beam used in aircraft spars are examined. Under the assumption that an aircraft spar is a cantilevered beam with a constant cross-section and is subjected to only bending, four kinds of webs are analyzed for three different sizes. To enable comparison, each hole has the same area and are subjected to the same load by using EDISON 2D Continuum analysis. While circular hole is the most often used, elliptic one is obtained with the minimum von-Mises stress by about 40% decreased. To verify the results gathered by EDISON, comparison was made with ANSYS and analytic predictions obtained with the stress intensity factor K. As comparison shows insignificant discrepancies, it is concluded that a well-designed beam with elliptic holes will be the most efficient spar regarding weight to rigidity ratio in terms of the bending stress.

• Transactions of Materials Processing
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• v.11 no.8
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• pp.724-730
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the present work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section extrusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• The KSFM Journal of Fluid Machinery
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• v.15 no.5
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• pp.42-47
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• 2012

Newly updated wing shape to apply small vertical wind turbine is tested with digital wind tunnel in this study. Digital wind tunnel is designed to reduce length of wind tunnel and also to maximize its area of test section. Same DC fans of ninety six are installed in the end side of its rectangular duct and air can be blown out to the other side to have uniform flow with same electricity power. New wing is concluded using experimental plan and analysis with 4-parameters and 3-levels, and tested with digital wind tunnel. It shows better performance in lift to drag ratio, and can applied to the wind turbine for the higher torque and lower thrust.

• Journal of the East Asian Society of Dietary Life
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• v.2 no.2
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• pp.277-282
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• 1992

This study was designedto investigate changes in phsicochemical properties of rice extrudate with added glycerin fatty acid ester extruded by single screw extruder. According to emulsifier content, expansion ratio and water solubility index were represented minimum in rice extrudate with added 2.0% and 2.5% glycerin fatty acid ester. Extrudate with added 1.5% emulsifier revealed lowest break strength and bulk density, so got a tender and light texture. Meanwhile water absorption index was showed maximum at 1.5% emulsifier content. As emulsifier content increased, lightness raised. By the microstructure obsorved with image analyzer, addition of emulsifier had decreased area and fractarea of air cells of cross section of extrudates. On the results of this research, quality of extrudate with added 1.5% glycerin fatty acid ester was considered very well than 100% rice extrudate, because of tender and light texture, highest water absorption indexand fine structure with higher lightness.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.77-80
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• 2004

In bridge deck systems, deflections and cracking can be controlled by longitudinal and transverse prestressing, There are some benefits, longitudinal cracking control, the thickness reduction of deck slab, the widening of deck width and the reduction of the cross section area, in transversely post-tensioned concrete box girder bridges. However, it has been not sufficient to study the structural behaviors of transversely post-tensioned concrete box girder. Therefore, It is needed to predict the structural behaviors by prestressing and static loading. In this study, the analytical and experimental load tests are carried out to study the effect of transverse prestressing on concrete box girder. For these objectives, four test specimens are fabricated with various tendon spacing and steel ratio of top slab. The analytical and experimental studies are performed to estimate effects of the prestressing and failure tests.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.2
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• pp.269-276
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• 2001

This paper dipicts the computational results for the axisymmetric subsonic/sonic ejector systems with a second throat. The numerical simulations are based on a fully implicit finite volume scheme of the compressible Reynolds-Averaged Navier-Stokes equation in a domain that extends from the stagnation chamber to the ejector diffuser exit. In order to obtain practical design factors for subsonic/sonic ejector systems, the ejector throat area, the mixing section configuration, and the ejector throat length were changed in computations. For the subsonic/sonic ejector systems operating in the range of low operation pressure ratio, the effects of the design factors on the flow are discussed.

• Wind and Structures
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• v.17 no.5
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• pp.537-552
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• 2013

Wind tunnel experiments were performed to study the wind loads on an inclined flat plate with and without a guide plate. Highly turbulent flow, which corresponded to free-stream turbulence intensity on the flat roof of low-rise buildings, was produced by a turbulence generation grid at the inlet of the test section. The test model could represent a typical solar collector panel of a solar water heater. There are up-stream movements of the separation bubble and side-edge vortices, more intense fluctuating pressure and a higher bending moment in the turbulent flow. A guide plate would result in higher lift coefficient, particularly with an increased projected area ratio of a guide plate to an inclined flat plate. The value of lift coefficient is considerably lower with increased free-stream turbulent intensity.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.6
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• pp.73-83
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• 2016

Bearing stress near anchor plates is usually very high due to prestressing force in anchorage zone of concrete structure used post-tensioned prestressed method. In order to effective utilization of cross section and crack control, appropriate size of anchorage plates should be used to prevent crack initiation and failure of concrete structures eventually. This study aims to suggest equation for effective area of bearing plate of rectangle type and circular type by Highway Bridge Design Specification and PTI etc. A shape factor according to bearing plate shape is suggested based on numerical analysis, and it can be used suitability for design of special anchorage plate dimension.

• Journal of Korean Association for Spatial Structures
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• v.12 no.4
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• pp.47-56
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• 2012

This paper describes the structural design and optimization of sinusoidally corrugated web girder by using EUROCODE (EN 1993-1-5). The optimum design methodology and characteristics of the optimal cross-section are discussed. We investigate a shear buckling and the concerned standards for corrugated web and explain the equations to obtain a critical stress according to buckling type. In order to perform optimization, we consider an objective function as minimum weight of the girder and use the constraint functions as slenderness ratio and stresses of flanges as well as corrugated web and deflection. Genetic Algorithm is adopted to search a global optimum solution for this mathematical model. For numerical example, the clamped girder under the concentrated load is considered, while the optimum cross-sectional area and design variables are analyzed. From the results of the adopted example, the optimum design program of the sinusoidally corrugated web girder is able to find the suitable solution which satisfied a condition subject to constraint functions. The optimum design shows the tendency to decrease the cross-sectional area with the yielding strength increase and increase the areas with load increase. Moreover, the corrugated web thickness shows a stable increase concerning the load.