• Title/Summary/Keyword: boundary characteristics

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A Study on the Transition of Spatial Structure in Libraries with Special Reference to Rhizome and Hypertext (리좀과 하이퍼텍스트 관점에서 본 도서관 공간구조의 이해)

  • Choi, Yoon-Kyung;Kim, Min-Jung
    • Korean Institute of Interior Design Journal
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    • v.15 no.6 s.59
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    • pp.111-119
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    • 2006
  • The spatial property of contemporary library is now rapidly changing through the spatial expansion of knowledge and information, the reduction of information storing facility, the variation of approaching methods by digital shift and the transition of social recognition as a cultural facility. Also the spatial characteristics with referring characters have developed such as, decentralization, de-construction, de-boundary, individual space, erasing of boundary, flow of space which extends infinitely. The main process of library origination, the systematic classification, and the storage system concluding with the demand and value of the information by changing social demands and the role of the widest ranged facility. And 5 themes, such as, hierarchy, center, storage, boundary, and symbol, as a changed spatial concept and analyzed in the case of library plans and libraries which are actually built. The significant purpose of this research is to propose that rhizomatous intellectuality and hypertext could be a theoretical background of the contemporary architecture and could be a viewpoint of the transition of spatial structure in libraries. A future library should have spatial property embracing various social changes and needs and for this respect, it is necessary to approach and analyze through the architectural explication from diverging points of view.

Algorithm for extracting region of interest in medical images using image processing techniques (영상처리 기법을 이용한 의료 영상에서 관심영역 추출 알고리즘)

  • Cho, Young-bok;Woo, Sung-hee
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2018.10a
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    • pp.295-298
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    • 2018
  • The proposed paper proposes an algorithm that automatically extracts the region of interest using image processing techniques for medical images. In general, the robust boundary segmentation technique provides robust and accurate segmentation results in object boundaries with various noise and direction generated during image acquisition through optimal segmentation of the edges considering noise characteristics and directionality in noise images. In this paper, it is possible to apply adaptive filter type and size to the structural information of the image object and apply it to the boundary division of various object objects. In addition, it is possible to divide the boundary between various noise images such as an ultrasound image and an optical image.

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Heat Transfer Characteristics of the Interaction Between Bulk Flow Pulsation and a Vortex Embedded in a Turbulent Boundary Layer (주유동 맥동과 경계층 와류의 상호작용이 벽면 열전달에 미치는 영향)

  • Gang, Sae-Byeol;Maeng, Du-Jin;Lee, Jun-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.25 no.3
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    • pp.381-388
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    • 2001
  • Presented are heat data which describe the effect of interaction between bulk flow pulsations and a vortex embedded in a turbulent boundary layer. The pulsation frequencies are 3 Hz, 15 Hz and 30 Hz. A half delta wing with the same height as the boundary layer thickness is used to generate the vortex flow. The convection heat transfer coefficients on a constant heat-flux surface are measured by embedded 77 T-type thermocouples. Spanwise profiles of convection heat transfer coefficients show that upwash region of vortex flow is influenced by bulk flow pulsations. The local heat transfer coefficient increases approximately by 7 percent. The increase in the local change of convection heat transfer coefficient is attributed to the spanwise oscillatory motion of vortex flow especially at the low Strouhal number and to the periodic change of vortex size.

Influence of the Wake Behind Rectangular Bars on the Flow and Heat Transfer in the Linear Turbine Cascade (사각주 후류가 선형터빈익렬의 유동 및 열전달에 미치는 영향에 관한 연구)

  • Yoon, Soon Hyun;Sim, Jae Kyung;Woo, Chang Soo;Lee, Dae Hee
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.23 no.7
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    • pp.864-870
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    • 1999
  • An experimental study Is conducted in a four-vane linear cascade in order to examine the influence of the wake behind rectangular bars on the flow and heat transfer characteristics. Flow and heat transfer measurements are made for the inlet Reynolds number of 66000(based on chord length and free-stream velocity). Turbulent intensity and stress are measured using a hot-wire anemometer, and to measure the convective heat transfer coefficients on the blade surface liquid crystal/gold film Intrex technique is used. Each of experimental cases is characterized by the unsteadiness measured at the entrance of the cascade. The wake behind the rectangular bars enhances the turbulent motion of the flow in the cascade passage. It also promotes the boundary layer development and transition. The results show that heat transfer coefficients on the blade surface increase with increasing unsteadiness.

Study on the Generation of Turbulent Boundary Layer in Wind Tunnel and the Effect of Aspect Ratio of a Rectangular Obstacle (풍동 내 난류 경계층 생성과 육면체의 형상 변화에 따른 표면 압력 변화 연구)

  • LimM, Hee-Chang;Jeong, Tae-Yoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.32 no.10
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    • pp.791-799
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    • 2008
  • We investigate the flow characteristics around a series of rectangular bodies ($40^d{\times}80^w{\times}80^h$, $80^d{\times}80^w{\times}80^h$ and $160^d{\times}80^w{\times}80^h$) placed in a deep turbulent boundary layer. The study is aiming to understand the surface pressure distribution around the bodies such as the suction pressure in the leading edge, when the flow is normal, which is responsible for producing extreme suction pressures on the roof. The experiment includes wind tunnel work by using HWA (Hot-Wire anemometry) and pressure transducers. The experiments are carried out at three different Reynolds numbers, based on the velocity U at the body height h, of $2.4{\times}10^4$, $4.6{\times}10^4$ and $6.7{\times}10^4$, and large enough that the mean flow is effectively Reynolds number independent. The results include the measurements of the growth of the turbulent boundary layer in the wind tunnel and the surface pressure around the bodies.

A Method to Extract Vehicle Number Plates by Applying Signal Processing Techniques (신호처리 기법을 응용한 차량번호판 추출방법)

  • 전병태;윤호섭
    • Journal of the Korean Institute of Telematics and Electronics B
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    • v.30B no.7
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    • pp.92-101
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    • 1993
  • This paper describes algorithms to extract license plates in vehicle images. Conventional methods perform preprocessing on the entire vehicle image to produce the edge image and binarize it. Hough transform is applied to the binary image to find horizontal and vertical lines, and the license plate area is extracted using the charateristics of license plates (the boundary information of license plates). Problems with this approach are that real-time processing is not feasible due to long processing time and that the license plate area is not extracted when lighting is irregular such as at night or when the plate boundary does not show up in the image. This research uses the gray level transition characteristics of license plates to verify the digit area by examining the digit width and the gray level difference between the background area the digit area, and then extracts the plate area by testing the distance between the verified digits. This research solves the probelm of failure in extracting the license plates due to degraded plate boundary as in the conventional methods and resolves the provlem of the time requirement by processing in real time such that practical application is possible.

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The effect of carbon nanotubes agglomeration on vibrational response of thick functionally graded sandwich plates

  • Tahouneh, Vahid
    • Steel and Composite Structures
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    • v.24 no.6
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    • pp.711-726
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    • 2017
  • In the present work, by considering the agglomeration effect of single-walled carbon nanotubes, free vibration characteristics of functionally graded (FG) nanocomposite sandwich plates resting on Pasternak foundation are presented. The volume fractions of randomly oriented agglomerated single-walled carbon nanotubes (SWCNTs) are assumed to be graded in the thickness direction. To determine the effect of CNT agglomeration on the elastic properties of CNT-reinforced composites, a two-parameter micromechanical model of agglomeration is employed. In this research work, an equivalent continuum model based on the Eshelby-Mori-Tanaka approach is employed to estimate the effective constitutive law of the elastic isotropic medium (matrix) with oriented straight CNTs. The 2-D generalized differential quadrature method (GDQM) as an efficient and accurate numerical tool is used to discretize the equations of motion and to implement the various boundary conditions. The proposed rectangular plates have two opposite edges simply supported, while all possible combinations of free, simply supported and clamped boundary conditions are applied to the other two edges. The benefit of using the considered power-law distribution is to illustrate and present useful results arising from symmetric and asymmetric profiles. The effects of two-parameter elastic foundation modulus, geometrical and material parameters together with the boundary conditions on the frequency parameters of the laminated FG nanocomposite plates are investigated. It is shown that the natural frequencies of structure are seriously affected by the influence of CNTs agglomeration. This study serves as a benchmark for assessing the validity of numerical methods or two-dimensional theories used to analysis of laminated plates.

Thermo-mechanical vibration analysis of functionally graded micro/nanoscale beams with porosities based on modified couple stress theory

  • Ebrahimi, Farzad;Mahmoodi, Fateme;Barati, Mohammad Reza
    • Advances in materials Research
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    • v.6 no.3
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    • pp.279-301
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    • 2017
  • Thermo-mechanical vibration characteristics of in homogeneousporous functionally graded (FG) micro/nanobeam subjected to various types of thermal loadings are investigated in the present paper based on modified couple stress theory with consideration of the exact position of neutral axis. The FG micro/nanobeam is modeled via a refined hyperbolic beam theory in which shear deformation effect is verified needless of shear correction factor. A modified power-law distribution which contains porosity volume fraction is used to describe the graded material properties of FG micro/nanobeam. Temperature field has uniform, linear and nonlinear distributions across the thickness. The governing equations and the related boundary conditions are derived by Extended Hamilton's principle and they are solved applying an analytical solution which satisfies various boundary conditions. A comparison study is performed to verify the present formulation with the known data in the literature and a good agreement is observed. The parametric study covered in this paper includes several parameters such as thermal loadings, porosity volume fraction, power-law exponents, slenderness ratio, scale parameter and various boundary conditions on natural frequencies of porous FG micro/nanobeams in detail.

Intake Flow Characteristics of HyShot Scramjet Engine (HyShot 스크램제트 엔진의 흡입구 유동특성 연구)

  • Won Su-Hee;Choi Jeong-Yeol;Jeung In-Seuck
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2004.10a
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    • pp.47-52
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    • 2004
  • In the design of scramjet intake for hypersonic flight, a variety of aerothermodynamics phenomena are encountered. These phenomena include blunt leading - edge effects, boundary layer development issues, transition, inviscid / viscous coupling, shock - shock interactions, shock / boundary - layer interactions, and flow profile effects. For intakes that are designed to operate within a narrow Mach number / altitude envelope, an understanding of a few of these phenomena might be required. In this work several predominant flowfield phenomena (viscous phenomena, boundary - layer separation, and combustor entrance profile) are discussed to investigate the performance of the intake at the altitude and angle of attack extremes of the HyShot flight experiment.

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Nonlocal vibration analysis of FG nano beams with different boundary conditions

  • Ehyaei, Javad;Ebrahimi, Farzad;Salari, Erfan
    • Advances in nano research
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    • v.4 no.2
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    • pp.85-111
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    • 2016
  • In this paper, the classical and non-classical boundary conditions effect on free vibration characteristics of functionally graded (FG) size-dependent nanobeams are investigated by presenting a semi analytical differential transform method (DTM) for the first time. Three kinds of mathematical models, namely; power law (P-FGM), sigmoid (S-FGM) and Mori-Tanaka (MT-FGM) distribution are considered to describe the material properties in the thickness direction. The nonlocal Eringen theory takes into account the effect of small size, which enables the present model to become effective in the analysis and design of nanosensors and nanoactuators. Governing equations are derived through Hamilton's principle and they are solved applying semi analytical differential transform method. The good agreement between the results of this article and those available in literature validated the presented approach. The detailed mathematical derivations are presented and numerical investigations are performed while the emphasis is placed on investigating the effect of the several parameters such as small scale effects, spring constant factors, various material compositions and mode number on the normalized natural frequencies of the FG nanobeams in detail. It is explicitly shown that the vibration of FG nanobeams is significantly influenced by these effects. Numerical results are presented to serve as benchmarks for future analyses of FG nanobeams.