• Structural Engineering and Mechanics
• /
• v.71 no.6
• /
• pp.751-761
• /
• 2019

Lamb wave technology is a promising technology in the field of structural health monitoring and can be applied in the detection and monitoring of defects in plate structures. Based on the reconstruction algorithm for the probabilistic inspection of damage (RAPID), a Lamb-based detection and evaluation method of through-thickness rectangular notches in metal plates was proposed in this study. The influences of through-thickness rectangular notch length and the angle between sensing path and notch length direction on signals were further explored through simulations and experiments. Then a damage index calculation method which focuses on both phase and amplitude difference between detected signals and baseline signals was proposed. Based on the damage index difference between two vertically crossed sensing paths which pass through the notch in a sensor network, the notch direction identification method was proposed. In addition, the notch length was determined based on the damage index distribution along sensing paths. The experimental results showed that the image reconstructed with the proposed method could reflect the information for the evaluation of notches.

• Structural Engineering and Mechanics
• /
• v.84 no.4
• /
• pp.561-573
• /
• 2022

This paper presents a new model to obtain the minimum area of the contact surface for rectangular isolated footings, considering that the contact surface works partially to compression (a part of the contact surface of the footing is subjected to compression and the other is not in compression or tension). The methodology is developed by integration to obtain the axial load "P", moment around the X axis "M_x" and moment around the Y axis "M_y". This document presents the simplified and precise equations of the four possible cases of footing subjected to uniaxial bending and five possible cases of footing subjected to biaxial bending. The current model considers the contact area of the footing that works totally in compression, and other models consider the contact area that works partially under compression and these are developed by very complex iterative processes. Numerical examples are presented to obtain the minimum area of rectangular footings under an axial load and moments in two directions, and the results are compared with those of other authors. The results show that the new model presents smaller areas than the other authors presented.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.22 no.1
• /
• pp.106-113
• /
• 2011

In this paper, the non-resonant SWG(Slotted Waveguide) antenna with double slots in narrow wall of rectangular waveguide is designed. Because energy radiated from each slot depends upon inclination angle of slot of the designed antenna, inclination angle of each slot is controlled to satisfy the amplitude distribution for required sidelobe level. Instead of the conventional extraction method of slot conductance, this amplitude distribution is made by the proposed method, which employs far-field radiation pattern calculated by Fourier transform of aperture field distribution on slot. The non-resonant double SWG antenna is designed by the proposed method and is manufactured. The antenna performances are measured and compared with the simulated results.

• Restorative Dentistry and Endodontics
• /
• v.34 no.1
• /
• pp.1-7
• /
• 2009

The purpose of this study was to compare the stress distributions of NiTi rotary instruments based on their cross-sectional geometries of triangular shape-based cross-sectional design, S-shaped cross-sectional design and modified rectangular shape-based one using 3D FE models. NiTi rotary files of S-shaped and modified rectangular design of cross-section such as Mtwo or NRT showed larger stress change while file rotation during simulated shaping. The stress of files with rectangular cross-section design such as Mtwo, NRT was distributed as an intermittent pattern along the long axis of file. On the other hand, the stress of files with triangular cross-section design was distributed continuously. When the residual stresses which could increase the risk of file fatigue fracture were analyzed after their withdrawal. the NRT and Mtwo model also presented higher residual stresses. From this result, it can be inferred that S-shaped and modified rectangular shape-based files were more susceptible to file fracture than the files having triangular shape-based one.

• Communications for Statistical Applications and Methods
• /
• v.31 no.3
• /
• pp.263-277
• /
• 2024

This paper proposes new parameterizations of the tilted beta binomial distribution, obtained from the combination of the binomial distribution and the tilted beta distribution, where the beta component of the mixture is parameterized as a function of their mean and variance. These new parameterized distributions include as particular cases the beta rectangular binomial and the beta binomial distributions. After that, we propose new linear regression models to deal with overdispersed binomial datasets. These new models are defined from the proposed new parameterization of the tilted beta binomial distribution, and assume regression structures for the mean and variance parameters. These new linear regression models are fitted by applying Bayesian methods and using the OpenBUGS software. The proposed regression models are fitted to a school absenteeism dataset and to the seeds germination rate according to the type seed and root.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2002.05a
• /
• pp.1067-1070
• /
• 2002

This paper deals with the factors affecting measurement of sound insulation performance of the ceiling panels. The factors to be experimently examined are as follows: sound diffuseness of the test room by investigating sound pressure distribution, Reverberation time, and influence of speaker location on measured results. Based on the investigation of sound pressure distribution over measuring points, it can draw a conclusion that rectangular shaped rooms as test rooms have a serious problem associated with the diffuse sound field.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1997.04a
• /
• pp.675-680
• /
• 1997

The object of this study is the numerical analysis about the sound pressure distribution in reverberation rooms. In order to obtain the effect of the boundary conditions of the wall, the sound field was computed for various absorption coefficients and impedances. And the effect of the room shape was investigated by dealing with pentagonal type as well as the rectangular type. In addition an experiment was performed for the sound pressure distribution in a reverberation room and the result was compared with the analysis.

• Journal of the Korean Data and Information Science Society
• /
• v.27 no.5
• /
• pp.1119-1131
• /
• 2016

The Neyman-Scott Rectangular Pulses Model (NSRPM) is mainly used to construct hourly rainfall series. This model uses a modest number of parameters to represent the rainfall processes and underlying physical phenomena, such as the arrival of storms or rain cells. In NSRPM, the method of moments has often been used because it is difficult to know the distribution of rainfall intensity. Recently, approximated likelihood function for NSRPM has been introduced. In this paper, we propose a hierarchical model for applying a spatial structure to the NSRPM parameters using the approximated likelihood function. The proposed method is applied to summer hourly precipitation data observed at 59 weather stations (Korea Meteorological Administration) from 1973 to 2011.

• Wind and Structures
• /
• v.20 no.1
• /
• pp.37-58
• /
• 2015

As wind flows around a sharp-edged body, the resulting separated flow becomes complicated, with multiple separations and reattachments as well as vortex recirculation. This widespread and unpredictable phenomenon has long been studied academically as well as in engineering applications. In this study, the flow characteristics around rectangular prisms with five different aspect ratios were determined through wind tunnel experiments and a detached eddy simulation, that placed the objects in a simulated deep turbulent boundary layer at $Re=4.6{\times}10^4$. A series of rectangular prisms with the same height (h = 80 mm), different longitudinal lengths (l = 0.5h, h, and 2h), or different transverse widths (w = 0.5h, h, and 2h) were employed to observe the effects of the aspect ratio. Furthermore, five wind directions ($0^{\circ}$, $10^{\circ}$, $20^{\circ}$, $30^{\circ}$, and $45^{\circ}$) were selected to observe the effects of the wind direction. The simulated results of the surface pressure were compared to the wind tunnel experiment results and the existing results of previous papers. The vortex and spectrum were also analyzed to determine the detailed flow structure around the body. The paper also highlights the pressure distribution around the rectangular prisms with respect to the different aspect ratios. With an increasing transverse width, the surface suction pressure on the top and side surfaces becomes stronger. In addition, depending on the wind direction, the pressure coefficient experiences a large variation and can even change from a negative to a positive value on the side surface of the cube model.

• Journal of Korean Society of Steel Construction
• /
• v.16 no.4 s.71
• /
• pp.463-470
• /
• 2004

In this study, the bearing pressure distribution and design method of rectangular steel tubular column base plates under concentric loading were investigated. In general, the size and thickness of the baseplate are determined with the assumption that the bearing pressure of the column baseplate is uniformly distributed. When the column is loaded lightly, however, the size of the baseplate becomes smaller, the thickness becomes thinner and the bearing pressure of the baseplate is not distributed evenly. In this study, the distribution of the bearing pressure was investigated using the experimental and analytical methods. Four test specimens of the rectangular steel column baseplate were fabricated and tested. The analysis of the specimens was done using the finite element analysis program ANSYS. The result was that it was appropriate to use the effective width method to design the lightly loaded column baseplate, because the bearing pressure was not distributed evenly and was only concentrated under the column section.