• Title/Summary/Keyword: 경계성

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Stability Robustness of Unified Decentralized Systems (단일 분산시스템의 강인안정성 해석)

  • Lee, Dong-Gi;Heo, Gwang-Hee;Oh, Do-Chang;Lee, Giu;Lee, Woo-Sang
    • Journal of the Institute of Electronics Engineers of Korea SC
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    • v.44 no.2 s.314
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    • pp.1-9
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    • 2007
  • In this paper, new results for perturbation bounds for unified decentralized systems by a unified approach using $\delta$ (defined as a shift operator at unified approach) are presented. Robust stability analysis of unified decentralized system is investigated by new robust stability bound under system uncertainties. New unified stability bounds are developed based on the unified Lyapunov matrix equation. It is shown that the system maintains its stability when new unified bounds are applied. Numerical example is presented to illustrate the proposed analysis.

A Study on the Application of Variable Safe-Guard Ring for the Ship Collision Avoidance in Shallow Water (천수역에서 충돌회피를 위한 가변안전경계영역 적용에 관한 연구)

  • Yang, Hyoung-Seon;Ahn, Young-Sup
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.14 no.2
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    • pp.157-162
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    • 2008
  • The ship's maneuverability is the important factor to avoid ship's collisions. The ship's maneuverability is usually measured in a deep water, and the turning ability is decreased and the course stability is improved in a shallow water. The variation of the turning ability could cause the risk of collision. In this paper, we proposes application technique of Variable Safe-Guard Ring to consider the shallow water effect and to be simple to estimate the grade of collision risk simultaneously. Through the mathematical simulation, the availability of new method was varified. Therefore this method is expected enough to support a maneuver for collision avoidance.

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Robust edge Detector Based on Dual Filters (이중 필터를 이용한 굳건한 경계선 검출기)

  • 이해성;조영범;변혜란;유지상
    • Proceedings of the Korean Information Science Society Conference
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    • 1999.10b
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    • pp.503-505
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    • 1999
  • 경계선 검출은 컴퓨터를 이용한 영상인식의 첫 단계로서, 인식의 성능에 큰 영향을 미치는 중요한 기술이다. 여러 가지 경계선 검출 기술들이 존재하지만, 이들은 모두 주어진 영사에 잡음이 존재하지 않거나 존재의 정도가 미약한 경우를 가정하여 개발되었다. 한편, 잡음이 심하게 삽입된 경우에는 경계선 검출기 적용 이전에 잡음제거 필터를 사용할 수 있다. 그러나 주어진 영상에 잡음이 존재하는지를 어떻게 컴퓨터 스스로 판단할 것인가\ulcorner 본 연구에서는 주어진 영상에 대하여 잡음의 존재 여부와 잡음의 정도 여부에 상관없이, 굳건한 경계선 검출 능력을 보이는 경계선 검출기를 개발하였다. 이를 위하여 이중 필터를 사용하였는데, 그 중 하나는 일반적으로 많이 사용되는 가우시안 필터이고, 다른 하나는 본 연구진에 의하여 개발된 웨이블릿 기반 필터이다. 실험결과, 본 논문의 경계선 검출기는 잡음의 정도에 크게 구애받지 않는 일정한 성능을 보여주었다.

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乾燥摩擦과 경계마찰

  • 강용식
    • Tribology and Lubricants
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    • v.2 no.2
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    • pp.5-11
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    • 1986
  • 일반적으로 마찰면은 유체윤활과 경계윤활과의 혼합潤滑영역을 거쳐서 경계윤활을 주체로 하는 領域으로 옮겨가는 가능성을 항상 지니고 있다. 거기에서는 점도뿐만 아니라, 油性이나 극압성 등이 윤활특성에 중요한 영향을 끼체게 된다. 따라서 그 영역에 있어서의 윤활제의 역할을 인식하고, 적정한 평가를 하기 위해서는 마찰현상에 대한 이해가 필요하게 된다.

Finite Difference Stability Analysis of Anisotropic Plates with Free Edge (자유경계를 갖는 비등방성 판의 유한차분 안정성 해석)

  • Yoo, Yong Min;Lee, Sang Youl;Chang, Suk Yoon
    • Journal of Korean Society of Steel Construction
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    • v.12 no.2 s.45
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    • pp.221-230
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    • 2000
  • Checking the stability of anisotropic plates with free edges, it is impossible that buckling loads and modes are found via existing classical methods about various loads and boundary conditions. For solving this problems. finite difference method(FDM) is used to analyze the buckling behaviors for arbitrary boundary conditions. Using FDM, it is difficult to treat the fictitious points on free edges. So, this paper analyzes buckling behaviors of analytic models with one edge free and the other edges clamped and with opposite two edges free and other two edges clamped. The various buckling loads and mode characteristics through numerical results are given for buckling behaviors of anisotropic plates on free edges.

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Analysis of Moving Boundary Problem Using Extended Moving Least Squares Finite Difference Method (확장된 이동최소제곱 유한차분법을 이용한 이동경계문제의 해석)

  • Yoon, Young-Cheol;Kim, Do-Wan
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.4
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    • pp.315-322
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    • 2009
  • This paper presents a novel numerical method based on the extended moving least squares finite difference method(MLS FDM) for solving 1-D Stefan problem. The MLS FDM is employed for easy numerical modelling of the moving boundary and Taylor polynomial is extended using wedge function for accurate capturing of interfacial singularity. Difference equations for the governing equations are constructed by implicit method which makes the numerical method stable. Numerical experiments prove that the extended MLS FDM show high accuracy and efficiency in solving semi-infinite melting, cylindrical solidification problems with moving interfacial boundary.

Vagueness and the Context-Fixing Argument (모호성과 맥락고정논변)

  • Lee, Jun-Hyo
    • Korean Journal of Logic
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    • v.14 no.1
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    • pp.23-54
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    • 2011
  • In this paper, I introduce what Boundary-Shifting theories of vagueness (or Contextualism about vagueness) are and what the Context-Fixing Argument is, which is the most powerful and plausible objection to Boundary-Shifting theories. The basic idea of the Context-Fixing Argument is that vagueness still remains even if we hold the context fixed. Many objections based on this simple idea can be found in the literature on Boundary-Shifting theories. It seems that, without a convincing response to the Context-Fixing Argument, Boundary-Shifters must be in trouble. But, oddly, defenders of Boundary Shifters have said very little about this matter. In this situation, ${\AA}$kerman and Greenough try to defend Boundary-Shifting theories of vagueness by suggesting several answers. In this paper, I critically examine their suggestions and develop a new answer to the Context-Fixing Argument.

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Progressive Fracture Analysis of Concrete by Boundary Element Method and its Stabilizing Technique (경계요소법에 의한 콘크리트의 파괴진행해석 및 안정화 기법)

  • 송하원;전재홍
    • Magazine of the Korea Concrete Institute
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    • v.8 no.6
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    • pp.205-212
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    • 1996
  • This paper presents progressive fracture analysis of concrete using boundary element method and its stabilizing technique. To determine ultimate strength and to predict nonlinear behavior of concrete during progressive crack growth, the modelling of fracture process zone is done based on Dugdale-Barenblatt model with linear tension-softening curve. We regulate displacement and traction boundary integral equation of solids including crack boundary and analyze progressive fracture of concrete beam and compact tension specimen. Also a numerical technique which considers the growth of stress-free crack of concrete during the analysis and removes snapback of postpeak behavior is proposed.

An Optimization Model Based on Combining Possibility of Boundaries for Districting Problems (경계 결합 가능성 기반 구역설정 최적화 모델)

  • Kim, Kamyoung
    • Journal of the Korean Geographical Society
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    • v.49 no.3
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    • pp.423-437
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    • 2014
  • Districting is a spatial decision making process to make a new regional framework for affecting human activities. Natural barriers such as rivers and mountains located within a reorganized district may reduce the efficiency of reorganized human activities. This implies that it is necessary to consider boundary characteristics in a districting process. The purpose of this research is to develop a new spatial optimization model based on boundary characteristics for districting problems. The boundary characteristics are evaluated as continuous value expressing the possibility of combining adjacent two basic spatial units rather than a dichotomous value with 1 or 0 and are defined as an objective function in the model. In addition, the model has explicitly formulated contiguity constraints as well as constraints enforcing demand balance among districts such as population and area. The boundary attributes are categorized into physical and relational characteristics. Suitability analysis is used to combine various variables related to each boundary characteristic and to evaluate the coupling possibility between two neighboring basic units. The model is applied to an administrative redistricting problem. The analytical results demonstrate that various boundary characteristics could be modeled in terms of mixed integer programming (MIP).

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Intrinsically Extended Moving Least Squares Finite Difference Method for Potential Problems with Interfacial Boundary (계면경계를 갖는 포텐셜 문제 해석을 위한 내적확장된 이동최소제곱 유한차분법)

  • Yoon, Young-Cheol;Lee, Sang-Ho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.22 no.5
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    • pp.411-420
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    • 2009
  • This study presents an extended finite difference method based on moving least squares(MLS) method for solving potential problems with interfacial boundary. The approximation constructed from the MLS Taylor polynomial is modified by inserting of wedge functions for the interface modeling. Governing equations are node-wisely discretized without involving element or grid; immersion of interfacial condition into the approximation circumvents numerical difficulties owing to geometrical modeling of interface. Interface modeling introduces no additional unknowns in the system of equations but makes the system overdetermined. So, the numbers of unknowns and equations are equalized by the symmetrization of the stiffness matrix. Increase in computational effort is the trade-off for ease of interface modeling. Numerical results clearly show that the developed numerical scheme sharply describes the wedge behavior as well as jumps and efficiently and accurately solves potential problems with interface.