• Journal of Advanced Marine Engineering and Technology
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• v.24 no.4
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• pp.486-493
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• 2000

Flow mechanism around air flow sensor of electronic control engine, especially Karman vortex type, was investigated experimentally. The two-dimensional flow characteristics in the intermediate wake region behind a triangular vortex-generator respectively apex forward facing, apex backward facing and vertical flat plates following after apex forward facing(i.e vortex-flowmeter) were investigated at Reynolods number of $ReH=1.4\times10^4$; H is the width of a triangular vortex-generator. The vortex shedding frequency for wide Reynolds number from $7\times10^3$ to $2.1\times10^4$ was also surveyed. The velocity component was measured by X-type hot wire anemometer at 8H downstream from the bluff body. The coherent structure of the intermediate wake behind a bluff body was obtained by conditional phase average technique. As a result, it was verified that the vertical flat plates following after apex forward triangular vortex-generator make not only more linear relation between free stream velocity and vortex shedding frequency but also more periodic vortex in the vicinity of the center of wake.

• Proceedings of the KSME Conference
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• 2001.11b
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• pp.36-41
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• 2001

In order to simulate wake of stator and a gas turbine engine's balde row, acryl cylinder and a linear turbine cascade were used respectively in this study. Experimental of heat transfer distributions was done on the passage endwall and blade suction surface. Temperature distributions on the experimental regions were obtained through image processing system by using the cholesteric type liquid crystal which has chain structure of metyl$(CH_3)$. To represent the degree of heat transfer, dimensionless St number was used. The results show that heat transfer on the blade suction surface was increased due to the wake from the cylinder and was decreased as the distance between cylinder row and blade row increases. Because of groth of passage vortex, heat transfer distributions on the trailing edge area showed triangular shape which was little changed with wake. On the other hand, heat transfer on the passage endwall was decreased due to the wake from cylinder. As the distance between cylinder row and blade row increases, heat transfer was more decreased.

• International Journal of Fluid Machinery and Systems
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• v.9 no.2
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• pp.150-158
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• 2016

In this paper, a new framework that works the automatic execution with less design cycle time and human intervention bottlenecks is introduced to optimize the vortex shedder design by numerical integration method. This framework is based on iSIGHT combined with the pre-processor GAMBIT, and flow analysis software FLUENT. Two vortex shedders, circular with slit and triangular- semi circular cylinder, are employed as the designed models to be optimized, and DOE driver is used for optimization. According to the essential properties of a vortex shedder, it has found that the best diameters are 30mm for circular cylinder with slit and 30 to 35 mm for tri-semi cylinder. For slit ratio, 0.1 and 0.15 are the optimized values for circular with slit and tri-semi cylinder respectively. And it is found that these optimal results generated by DOE automated design cycle are in well agreement with the experiment.

• Journal of Biosystems Engineering
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• v.35 no.3
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• pp.197-205
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• 2010

An automatic echelon feeder of brown rice was presented for quality inspection system using color image processing. A echelon feeder was developed with vibratory feeder and cylindrical indent singulator having oblique light. The vibratory feeder consisted of a hopper, electromagnetic vibrator and multichannel grooves and supply the grain sample to the singulator. The feeding performance such as feed rate, blocking frequency of the channel was dependent on the size of groove and vibration pattern. A cylindrical indent singulator consisted of a rotating cylinder, prisms and a tungsten-halogen light source. It delivered grain kernels under the camera in a echelon form and illuminate the kernels with oblique ray and ambient light. The size of the indents installed on the surface of the rotating cylinder was determined by the dimensions of the paddy and a small triangular prism was placed in each indent to apply $ 20^{\circ}$ oblique light to the grain kernel.

• Journal of the Korean Society for Heat Treatment
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• v.10 no.1
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• pp.40-46
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• 1997

Although functionally gradient materials(FGM) has been developed so as to decrese the thermal stress induced by the high temperature difference between metal and ceramic, it is necessary to analyze the residual thermal stress for the fabrication of FGM. In order to reduce the residual thermal stress, compositional profile of SUS/PSZ(FGM) was suggested using finite element method(FEM). The stress analysis was made on the shape of cylinder with axial symmetry using two dimensional triangular element. For the case of various cylinder with different compositional gradient, calculated stress components were in reasonably good agreement with the expected ones. And the qualitative profile was suggested.

• The Journal of Korean Academy of Prosthodontics
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• v.35 no.1
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• pp.181-210
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• 1997

The stress distribution generated in the surrounding bone was calculated and compared for various geometry of the dental implants by means of the finite element methods. The models were designed to represent the screw type endosseous implants(varing the size, shape, direction of the screw thread and the angle of the body) with supporting bone and the cylinder type endosseous implants(varing the lower portion-Round type, tapered type) with supporting bone. Static mean bite forces were applied 100N vertically and 25N horizontally on the center of the implant and three dimensional finite analysis was undertaken using software ANSYS 5.1 Version. The result demonstrated that different implant shape leads to significant variations in stress distribution in the bone. In the case of variation of the screw size, direction and shape the implant model with normally directional and triangular screw implied lower stress than with upper directional or lower directional and quadrangular screw but among models a different screw size, within a variation of 0.2mm there was no meaningful difference in maximum stress. In the case of variation of angle of body the straight implied lower stress than the tapered. As a result of analysis of cylinder type, the implants with larger radius of curvature of the round form and larger diameter of the tapered form implied lower stress.

• Journal of Sasang Constitutional Medicine
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• v.18 no.3
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• pp.49-56
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• 2006

1. Objectives We are going to develope 3D Face Recognition Apparatus to analyse the facial characteristics of the Sasangin. In the process, we should identify a Hardware Error Analysis of this Apparatus. 2. Methods We verified The resolution, the repetition ability, the Flatness and the Cylindericity of 3D Face Recognition Apparatus by measuring a triangular pyramid, an exact square pillar and a cylinder. 3. Results and Conclusions In this test, The resolution of 3D-FARA was $0.0368mm{\times}0.0594mm{\times}0.2748mm(X{\times}Y{\times}Z)$, the repetition ability was 0.1187mm, the Flatness was 0.17188mm. the Flatness of triangular pyramid was 1.39034mm and the Cylindericity of cylinder was 3.1306mm. In conclusion, If we use 3D-FARA, It is necessary to complement the site of top of the nose and the outline of face, which is likely to occur hardware error, by using software invention or attaching the Land mark to subject.

• International Journal of High-Rise Buildings
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• v.8 no.4
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• pp.255-264
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• 2019

This paper describes large eddy simulation of wind pressures on a square cylinder in a uniform flow and a high-rise building immersed in an atmospheric turbulent boundary layer. For the atmospheric boundary layer case, the inflow turbulence is generated by a numerical wind tunnel. In the numerical simulation, particular attention is devoted to the performance of an auto hexahedral non-structural mesh. Both simulations are performed for three grid systems: an auto hexahedral non-structured grid, a structured Cartesian grid and a non-structured triangular prism grid, and for three grid numbers. The present study shows that the auto hexahedral unstructured mesh achieves the best simulation results for wind pressures on the square cylinder and the high-rise building. When the grid number is sufficiently large, the differences among the results obtained from the three investigated grid systems are not significant. However, the advantage of the auto hexahedral unstructured mesh becomes clear when the grid number decreases, because it enables a balanced distribution of orthogonal grids. The results described in this paper demonstrate that the auto hexahedral non-structured mesh has good potential applicability to simulation of urban flows.

• Journal of computational fluids engineering
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• v.12 no.3
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• pp.29-40
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• 2007

An implicit discontinuous Galerkin method for the two-dimensional Euler equations was developed on unstructured triangular meshes. The method can achieve high-order spatial accuracy by using hierachical basis functions based on Legendre polynomials. Numerical tests were conducted to estimate the convergence order of numerical solutions to the Ringleb flow and the supersonic vortex flow for which analytic solutions are available. Also, the flows around a 2-D circular cylinder and an NACA0012 airfoil were numerically simulated. The numerical results showed that the implicit discontinuous Galerkin methods couples with a high-order representation of curved solid boundaries can be an efficient method to obtain very accurate numerical solutions on unstructured meshes.

• Journal of computational fluids engineering
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• v.16 no.4
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• pp.72-83
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• 2011

A high-order discontinuous Galerkin method for the two-dimensional compressible Navier-Stokes equations was developed on unstructured triangular meshes. For this purpose, the BR2 methd(the second Bassi and Rebay discretization) was adopted for space discretization and an implicit Euler backward method was used for time integration. Numerical tests were conducted to estimate the convergence order of the numerical solutions of the Poiseuille flow for which analytic solutions are available for comparison. Also, the flows around a flat plate, a 2-D circular cylinder, and an NACA0012 airfoil were numerically simulated. The numerical results showed that the present implicit discontinuous Galerkin method is an efficient method to obtain very accurate numerical solutions of the compressible Navier-Stokes equations on unstructured meshes.