• 제목/요약/키워드: outer boundary

검색결과 357건 처리시간 0.027초

GIS 자료사용을 위한 건물 구축 알고리즘 개선 및 건물 주변 흐름과 확산 분석 (Improvement of Building-Construction Algorithm for Using GIS data and Analysis of Flow and Dispersion around Buildings)

  • 권아름;김재진
    • 대한원격탐사학회지
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    • 제30권6호
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    • pp.731-742
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    • 2014
  • 본 연구에서는 건물 꼭지점의 위 경도 좌표를 제공하는 GIS로부터 수치 모델의 건물 정보를 구축할 수 있는 알고리즘을 개선하였다. 이 알고리즘은 인접한 건물 꼭지점 위 경도 좌표를 지나는 선분을 순차적으로 연결하여 건물 외곽선을 구성하고, 외곽선 내부의 지점을 건물로 인식하기 때문에, Lee et al. (2009)에서 개발한 알고리즘의 한계를 개선하였고, 복잡한 형태의 건물을 실제에 가깝게 재현할 수 있었다. 본 연구에서는 GIS로부터 수치 건물을 구축할 때, 알고리즘 한계에 의해 발생한 건물 형태의 변화가 건물 주변의 흐름과 오염물질 확산에 미치는 영향을 조사하였다. 이를 위해, 알고리즘에 의한 건물 변형이 나타날 수 있는 세 가지 형태의 건물을 대상으로 전산유체역학 모델을 이용한 수치 실험을 수행하였다. 알고리즘 한계에 의해 발생한 건물 변형은 풍하영역의 흐름 패턴에는 상대적으로 작은 영향을 미쳤으나, 건물 사이의 공간에 나타나는 소용돌이와 같은 건물 규모 대기 현상의 수치 모의에는 매우 중요한 영향을 미쳤다. 건물 변형에 따른 건물 사이 공간의 축소는 건물 주위에 나타날 수 있는 소용돌이를 전혀 모의하지 못하거나 소용돌이 규모를 과소 모의 하는 등의 결과를 초래하였다. 건물 변형에 따른 평균 바람장 변화는 건물 주변 지역에서 배출된 스칼라 오염물질의 확산 패턴에도 큰 영향을 미침을 확인할 수 있었다.

물체 내부 윤곽선의 시각 작업기억 표상: 구멍이 있는 물체를 중심으로 (How is the inner contour of objects encoded in visual working memory: evidence from holes)

  • 김성호
    • 인지과학
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    • 제27권3호
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    • pp.355-376
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    • 2016
  • 이차원 표면에 난 구멍은 이를 둘러싼 물체에 의해 경계 지워진 빈 배경임에도 불구하고, 구멍의 모양은 다른 물체만큼 쉽게 지각된다. 즉, 구멍은 전경-배경 조직화의 깊이-형태 간 연결 관계(depth-shape coupling)를 예외적으로 위반하여, 깊이 상으로는 배경임에도 불구하고 형태를 갖는 준-전경적(quasi-figural) 사례처럼 보인다. 구멍의 준-전경적 속성을 지지하는 연구들은 구멍과 물체의 재인율이 유사하다는 기억 과제 결과에 주로 의존하고 있으므로, 구멍 모양의 기억이 지각적 처리에 기반하고 있는지는 불분명하다. 본 연구는 재인 과제보다 즉각적인 지각 처리를 반영하는 변화탐지 과제를 이용하여, 구멍을 경계 짓는 물체의 안쪽 윤곽선이 시각 작업기억에 어떻게 표상되는지 알아보았다. 이를 위해, 물체 내부에 다른 물체가 중첩된 접합 물체 조건과 구멍이 있는 물체 조건에서 안쪽 윤곽선과 바깥 영역의 색에 대한 변화탐지 수행을 비교하였다. 시각 작업기억의 선행 연구들은 형태나 방향과 같은 물체의 윤곽선 속성(boundary feature)이 표면 속성(surface feature)과 함께 통합되어 하나의 물체로 저장됨을 시사한다. 만일 구멍의 경계선이 구멍을 둘러싼 물체에 지각적으로 할당된다면, 이 경계선과 물체의 표면색이 통합적으로 부호화되는 물체 중심적 처리 이득으로 인해, 구멍 자극 조건에서 접합 자극 조건보다 높은 변화 탐지 수행이 예측되었다. 두 실험의 결과, 구멍 자극 조건의 변화 탐지 수행은 접합 자극 조건과 다르지 않았다. 이는 물체 내부의 윤곽선(구멍의 경계선) 속성이 물체의 표면 속성과 통합적으로 부호화되지 않으며, 구멍을 둘러싼 물체와 독립적으로 처리됨을 시사한다.

Free vibrations of anisotropic rectangular plates with holes and attached masses

  • Rossit, C.A.;Ciancio, P.M.
    • Structural Engineering and Mechanics
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    • 제28권1호
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    • pp.53-67
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    • 2008
  • Anisotropic materials are increasingly required in modern technological applications. Certainly, civil, mechanical and naval engineers frequently deal with the situation of analyzing the dynamical behaviour of structural elements being composed of such materials. For example, panels of anisotropic materials must sometimes support electromechanical engines, and besides, holes are performed in them for operational reasons e.g., conduits, ducts or electrical connections. This study is concerned with the natural frequencies and normal modes of vibration of rectangular anisotropic plates supported by different combinations of the classical boundary conditions: clamped, simply - supported and free, and with additional complexities such holes of free boundaries and attached concentrated masses. A variational approach (the well known Ritz method) is used, where the displacement amplitude is approximated by a set of beam functions in each coordinate direction corresponding to the sides of the rectangular plate. Consequently each coordinate function satisfies the essential boundary conditions at the outer edge of the plate. The influence of the position and magnitude of both hole and mass, on the natural frequencies and modal shapes of vibration are studied for a generic anisotropic material. The classical Ritz method with beam functions as spatial approximation proved to be a suitable procedure to solve a problem of such analytical complexity.

경계요소법을 이용한 3차원 정자장해석 (3-D Magnetostatic Field Analysis Using Boundary Element Method)

  • 전기억;고창섭;정현교;한송엽
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1991년도 하계학술대회 논문집
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    • pp.97-101
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    • 1991
  • A three-dimensional magnetostatic problem is analyzed using the boundary element method and the magnetic scalar potential are employed in order to reduce the size of system matrix. Although the total magnetic scalar potential gives very accurate solutions in inner and outer regions of magnetic material, it has limitation on application because the magnetic scalar potential due to applied magnetic field sources is hard to be obtained. The reduced magnetic scalar potential gives more or less inaccurate solutions inside the magnetic material but very accurate solutions outside. Hence it can be concluded that the reduced magnetic scalar potential is very useful when the magnetic fields of outside magnetic material only are interested. It is also shown, from the numerical results, that the linear shape function gives more efficient solutions than the constant shape functions because the former gives more accurate solutions in spite of relatively fewer unknowns than the latter.

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복사열과 부분열림이 자연대류에 미치는 영향에 관한 연구 (Natural Convection Coupled with Thermal Radiation within Partially Open Enclosure)

  • 노승균;김광선;이재효
    • 대한기계학회논문집
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    • 제18권11호
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    • pp.2999-3007
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    • 1994
  • The unsteady numerical simulations have been presented for the laminar natural convection in a partially open compartment. Computations were performed within the domain of the compartment in order to show the thermal radiation and the partially opening effects on the flow fields and heat transfer characteristics. The results were shown for different Planck numbers(0.05~5) and opening ratios(0.25~0.75) being fixed with Ra=$10^5$ and Pr=0.71. Considering the flow which is buoyancy driven from the heated wall, and the buoyancy is not much affected by the further outside region from the opening, the numerical computations have been performed without an outer region by the particular boundary treatments on the flow velocity and temperature at the different partial openings. The confined numerical domain reduced the CPU time and the memory of computer. P-1 approximation of radiative transfer equation was employed with Marshak type boundary conditions along with the pseudo-black body approximation at the partial openings. The numerical results clearly show that the natural convective flow and heat transfer are much affected by increase of thermal radiation particularly from the initial state. When thermal radiation is not much affecting the flow ($PL{\le}1$), it was found that thermal radiation effects are almost negligible.

유체에 부분적으로 둘러싸인 사각형 용기의 접수진동 (Hydroelastic Vibration of a Rectangular Tank Partially Surrounding with a Liquid)

  • 정경훈;김종욱
    • 한국소음진동공학회논문집
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    • 제25권3호
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    • pp.207-215
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    • 2015
  • This paper deals with a theoretical method to calculate natural frequencies of a fixed-free rectangular tank partially in contact with an outer water gap. Orthogonal polynomials satisfying the boundary conditions of the tank are used as admissible functions in the Rayleigh-Ritz method. A quarter model of the liquid-coupled system is constructed and it is simplified to a line supported flat plate in contact with the liquid. The liquid displacement potential functions satisfying the Laplace equation and water boundary conditions are derived, and the finite Fourier transform is accomplished in conjunction with the compatibility requirement along the contacting interfaces between the tank and water. An eigenvalue problem is derived so that the natural frequencies of the wet rectangular tank can be extracted. The predictions from the proposed analytical method show good agreement with the finite element analysis results.

MATHEMATICAL MODELLING AND ITS SIMULATION OF A QUASI-STATIC THERMOELASTIC PROBLEM IN A SEMI-INFINITE HOLLOW CIRCULAR DISK DUE TO INTERNAL HEAT GENERATION

  • Gaikwad, Kishor R.
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • 제19권1호
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    • pp.69-81
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    • 2015
  • The present paper deals with the determination of temperature, displacement and thermal stresses in a semi-infinite hollow circular disk due to internal heat generation within it. Initially the disk is kept at arbitrary temperature F(r, z). For times t > 0 heat is generated within the circular disk at a rate of g(r, z, t) $Btu/hr.ft^3$. The heat flux is applied on the inner circular boundary (r = a) and the outer circular boundary (r = b). Also, the lower surface (z = 0) is kept at temperature $Q_3(r,t)$ and the upper surface ($Z={\infty}$) is kept at zero temperature. Hollow circular disk extends in the z-direction from z = 0 to infinity. The governing heat conduction equation has been solved by using finite Hankel transform and the generalized finite Fourier transform. As a special case mathematical model is constructed for different metallic disk have been considered. The results are obtained in series form in terms of Bessel's functions. These have been computed numerically and illustrated graphically.

칼라 나사 검사를 위한 표면 영역 자동 검출 (Seoul National University of Science and Technology)

  • 송태훈;하종은
    • 한국전자통신학회논문지
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    • 제11권1호
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    • pp.107-112
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    • 2016
  • 나사는 산업의 모든 분야에서 널리 사용되는 중요한 부품이다. 최근에는 여러 가지 필요에 의해 다양한 칼라 나사가 출시되고 있다. 이에 따라 제조 공정상에서 실시간 품질 검사가 요구되고 있다. 본 논문에서는 칼라 정보와 동적 계획법(Dynamic Programming) 알고리듬을 이용한 칼라 나사 검사를 위한 표면 영역 자동 추출 알고리듬에 대해 다루도록 한다. 나사의 외곽 경계는 칼라 성분의 차이를 이용하여 보다 강인한 검출이 가능하도록 한다. 나사의 내부 경계는 직교 좌표계를 극좌표계로 변환후 흑백 이미지상에서 일정 영역의 밝기값 차이를 이용한 동적 계획법을 적용하여 추출하도록 한다. 실험에서는 동일한 인자값을 이용한 결과를 분석하도록 한다.

Effect of chiral structure for free vibration of DWCNTs: Modal analysis

  • Asghar, Sehar;Naeem, Muhammad N.;Khadimallah, Mohamed Amine;Hussain, Muzamal;Iqbal, Zafar;Tounsi, Abdelouahed
    • Advances in concrete construction
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    • 제9권6호
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    • pp.577-588
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    • 2020
  • In this paper, vibration attributes of chiral double-walled carbon nanotubes (CNTs) based on nonlocal elastic shell model have been investigated. The impact of small scale is being perceived by establishing Flügge shell model. The wave propagation is engaged to frame the ruling equations as eigen value system. The influence of nonlocal parameter subjected to different end supports has been overtly examined. A suitable choice of material properties and nonlocal parameter been focused to analyze the vibration characteristics. The new set of inner and outer tubes radii investigated in detail against aspect ratio and length. The dominance of boundary conditions via nonlocal parameter is shown graphically. Whereas for lower aspect ratio the frequencies coincide but as it continues to expand the difference between all respective boundary conditions slightly tend to increase. The results generated furnish the evidence regarding applicability of nonlocal shell model and also verified by earlier published literature.

대구시 공공도서관 분관 봉사권역 설정에 관한 연구-대구권을 중심으로 한 이론적 모형

  • 손정표
    • 한국도서관정보학회지
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    • 제6권
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    • pp.105-140
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    • 1979
  • This study is an attempt to present a model of the effective service area for branch library system planning in Dae Gu city as one of large urban public libraries in Korea. This model is built up through the analysis of the distribution of population and characteristics of community structure, based on the standard for the branch library system of a public library. The results are summarized as follows: 1. Under the circumstances of this country, each radius of the effective service area for branch libraries are as follows; $1{\sim}1.5km$. is adequate for the central library and major branches; 1km. for neighborhood branches; $0.5{\sim}0.8km$. for sub-branches. 2. Population within the radius of the effective service area of a given branch may range from 80,000 to 100,000 for major branches, from 50,000 to 60,000 for neighborhood branches, and from 20,000 to 30,000 for sub-branches. 3. The radius of the outer boundary for the effective service area may be between 4km. and 5km. from the heart of the city, and the inner boundary, 13.km. 4. Areas with the radius between 2km. and 3km. from the heart of the city may be selected as the most effective locations for branch libraries, and between 3km. and 4km. as the next priority. 5. The number of service areas may be 14, that is, 7 major branches(Sinam, Sinchun, Susung, Daemyung, Naedang, Dalsung, Rowon), 2 neighborhood branches (Pyungri, Nambu), and 5 sub-branches(Chimsan, Sangiuk, Bongduk, Hyomok, Dongchon)

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