• Wind and Structures
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• v.21 no.2
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• pp.183-202
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• 2015

Experiments on two-dimensional rectangular prisms with various side ratios (B/D=2, 3, and 4, where B is the along-wind dimension, and D is the across-wind dimension) and rounded corners (R/D=0%, 5%, 10%, and 15%, where R is the corner radius) are reported in this study. The tests were conducted in low-turbulence uniform flow to measure the wind pressures on the surfaces of 12 models for Reynolds numbers ranging from $1.1{\times}10^5$ to $6.8{\times}10^5$. The aerodynamic force coefficients were obtained by integrating the wind pressure coefficients around the model surface. Experimental results of wind pressure distributions, aerodynamic force coefficients, and Strouhal numbers are presented for the 12 models. The mechanisms of the Reynolds number effects are revealed by analyzing the variations of wind pressure distributions. The sensitivity of aerodynamic behavior to the Reynolds number increases with increasing side ratio or rounded corner ratio for rectangular prisms. In addition, the variations of the mean pressure distributions and the pressure correlations on the side surfaces of rectangular prisms with the rounded corner ratio are analyzed at $Re=3.4{\times}10^5$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.6
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• pp.1244-1250
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• 1997

An arbitrary shaped iris in rectangular waveguideis investigated using FEM-CDMA with triangularprism elements in this paper. The volume of irisis subdivided into a relatively small number of triangular prism elements and FEM is used to formulate the field distribution. On the other hand, the fields in the waveguide region are represented by BIM derived from the waveguide Green's function and boundary conditions. The proposed method is verified through the design and experiment for the circular iris filter using WR-90 waveguide.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.2
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• pp.35-44
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• 1999

High negative pressure coefficient is formed in the corner of the bluff body structures. For many curtain wall designers this phenomena is of interest because this high negative pressure coefficient is adopted in structural calculation. The present study is aimed to investigate shedding vortex characteristics of two-dimensional rectangular prism flow. Unsteady calculation by finite difference method based upon SOLA is carried out for three aspect ratios(1:1, 1:2, 1:3) of Re=10$^4$ in viscous incompressible flow within infinite domain. Fluctuation of velocity components at various pick-up points and time variation of drag and lift coefficients are analysed by FFT method to reveal shedding vortex frequency patterns. At aspect ratio 1:1, one primary Strouhal number appears for about all pick-up points. At aspect ratio 1:2, two representative Strouhal numbers are classified by pick-up positions and their flows show two different reattachment patterns. For aspect ratio 1:3, frequency spectrum maintains multiple peaks.

• Korean Journal of Computational Design and Engineering
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• v.10 no.1
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• pp.70-75
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• 2005

A 3D solid element mesh generation algorithm was newly developed. 3D surface points of global rectangular coordinates were supplied by a 3D laser scanner. The algorithm is strait forward and simple but it generates mixed solid elements such as hexagonal, pyramid and prism types. Then, the surface triangular or rectangular elements were generated from the solid elements. The key of the algorithm is elimination of elements and 3D adaptive surface smoothing using given 3D surface point data.

• Wind and Structures
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• v.20 no.5
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• pp.661-682
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• 2015

This study investigates the use of time-frequency coherence analysis for detecting and evaluating coherent "structures" of surface pressures and wind turbulence components, simultaneously on the time-frequency plane. The continuous wavelet transform-based coherence is employed in this time-frequency examination since it enables multi-resolution analysis of non-stationary signals. The wavelet coherence quantity is used to identify highly coherent "events" and the "coherent structure" of both wind turbulence components and surface pressures on rectangular prisms, which are measured experimentally. The study also examines, by proposing a "modified" complex Morlet wavelet function, the influence of the time-frequency resolution and wavelet parameters (i.e., central frequency and bandwidth) on the wavelet coherence of the surface pressures. It is found that the time-frequency resolution may significantly affect the accuracy of the time-frequency coherence; the selection of the central frequency in the modified complex Morlet wavelet is the key parameter for the time-frequency resolution analysis. Furthermore, the concepts of time-averaged wavelet coherence and wavelet coherence ridge are used to better investigate the time-frequency coherence, the coherently dominant events and the time-varying coherence distribution. Experimental data derived from physical measurements of turbulent flow and surface pressures on rectangular prisms with slenderness ratios B/D=1:1 and B/D=5:1, are analyzed.

• Transactions of Materials Processing
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• v.23 no.1
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• pp.16-22
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• 2014

The current study presents a simple setup method for making teeth models using a three-axis CNC milling machine. Physical teeth models can be made by several methods: casting, machining, and three-dimensional printing. Since the shape of a teeth model requires five-axis machining, the machining of a teeth model using a three-axis CNC milling machine requires careful setup operations. In this paper a simple datum shape is designed within the work piece of the teeth model. The datum shape is an n-sided prism with regular n-polygon ends and rectangular sides. In the present study a 12-sided prism is used, which easily makes 30 degree rotations for finish machining. The proposed setup approach does not require any special tools for making the teeth model using a three-axis CNC milling machine. A test was run and the results show that the proposed approach is useful for experimental makings with the limited facilities available.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.78-81
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• 2000

The test specimen proposed in this study, named the bimaterial eccentric compression specimen, is a rectangular prism of two dissimilar materials with a notch at their interface. Normalized energy release rates and phase angles were calibrated with the finite element method. The normalized energy release rate increases with notch ratio but decreases with E2/E2, loading point, and phase angle, Bimaterial specimens consisting of mortar and ploymer as well as mortar and rock were prepared and tested to simulate fracture behavior ar the interface. Test results have confirmed that initial notch has significant effect on the apparent interfacial toughness.

• The Journal of Advanced Prosthodontics
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• v.12 no.1
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• pp.9-14
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• 2020

PURPOSE. The aim of this study was to investigate the effect of different numbers of heat treatments applied to superstructure porcelain on optical, thermal, and phase formation properties of zirconia. MATERIALS AND METHODS. Forty zirconia specimens were prepared in the form of rectangular prism. Specimens were divided into four groups (n = 10) according to the number of firing at heating values of porcelain. Color differences and translucency parameter were measured, and X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were performed. Data were analyzed with analysis of variance (ANOVA). RESULTS. There were no statistically significant differences in ∆E, TP, L, a, and b value changes of the zirconia specimens as a result of repetitive firing processes (P>.05). CONCLUSION. Although additional firing processes up to 4 increase peak density in thermal analysis, additional firing processes up to 4 times can be applied safely as they do not result in a change in color and phase character of zircon frameworks.

• Economic and Environmental Geology
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• v.18 no.2
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• pp.159-166
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• 1985

The computation of gravity anomalies by multi pole expansion is derived and compared with exact calculation for right rectangular prisms and right circular cylinders. For sources near field points, the multipole expansion results in a better approximation in volume integrals than in surface integrals. Nonetheless two approximate methods are coincident in the far-field of the general geophyical prospecting.

• Journal of Educational Research in Mathematics
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• v.21 no.3
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• pp.221-237
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• 2011

This paper focused on three drawbacks exposed in subject matter related to solid figures in elementary school math textbook. First, general solid figure are introduced before rectangular parallelepiped and cube in fifth grade math textbook, and prism and pyramid in sixth grade math textbook are introduced. Second, the process of abstraction from concrete objects to solid figures is insufficient in sixth grade math textbook. Third, some definitions in subject matter related to solid figures are inconsistent and ambiguous. The following four suggestions can be put forward as a conclusion based on these results. First, subject matter in textbooks must be correspond with that in curriculum. Second, it is necessary to inform teachers of range of subject matter through teachers guide book and manual for curriculum definitely. Third, each grade subject matter in math textbooks must be reexamined. Fourth, regular modification of math textbooks must be possible institutionally.