• Journal of information and communication convergence engineering
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• 제11권2호
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• pp.69-81
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• 2013

Maintaining connectivity is essential in multi-hop wireless networks since the network topology cannot be pre-determined due to mobility and environmental effects. To maintain the connectivity, a critical point in the network topology should be identified where the critical point is the link or node that partitions the network when it fails. In this paper, we propose a new critical point identification algorithm and also present numerical results that compare the critical points of the network and H-hop sub-network illustrating how effectively sub-network information can detect the network-wide critical points. Then, we propose two localized topological control resilient schemes that can be applied to both global and local H-hop sub-network critical points to improve the network connectivity and the network resilience. Numerical studies to evaluate the proposed schemes under node and link failure network conditions show that our proposed resilient schemes increase the probability of the network being connected in variety of link and node failure conditions.

• Architectural research
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• 제18권3호
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• pp.113-120
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• 2016

The stability and resistance of the plates under in-plane loading is crucial in the design of structures. For the assessment of structural stability, it is necessarily required to have accurate finite element technologies. Therefore, the enhanced 9-node plate (Q9-ANS) element is introduced for the linear buckling analysis of plate where the critical buckling load has to be determined. The Q9-ANS is developed with the Reissner-Mindlin (RM) assumptions which consider transverse shear deformation of the plate. Assumed shear strain is used to alleviate the shear locking phenomenon. Numerical examples are carried out to verify the performance of the Q9-ANS element in calculation of critical buckling load of the plates.

• 산업경영시스템학회지
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• 제22권51호
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• pp.189-197
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• 1999

Assembly line balancing problem is known as one of difficult combinatorial optimization problems. This problem has been solved with linear programming, dynamic programming approaches. but unfortunately these approaches do not lead to efficient algorithms. Recently, genetic algorithm has been recognized as an efficient procedure for solving hard combinatorial optimization problems, but has a defect that requires long-run time and computational complexties to find the solution. For this reason, we adapt a new method called the Critical Node Method that is intuitive, easy to understand, simple for implementation. Fuzzy set theory is frequently used to represent uncertainty of information. In this paper, to treat the data of real world problems we use a fuzzy number to represent the duration and Critical Node Method based heuristic procedure is developed for solving fuzzy assembly line balancing problem.

• Journal of Electrical Engineering and Technology
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• 제8권2호
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• pp.206-214
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• 2013

This paper proposes a new method for monitoring local voltage stability using the saddle node bifurcation set or loadability boundary in two dimensional power parameter space. The method includes three main steps. First step is to determine the critical buses and the second step is building the static voltage stability boundary or the saddle node bifurcation set. Final step is monitoring the voltage stability through the distance from current operating point to the boundary. Critical buses are defined through the right eigenvector by direct method. The boundary of the static voltage stability region is a quadratic curve that can be obtained by the proposed method that is combining a variation of standard direct method and Thevenin equivalent model of electric power system. And finally the distance is computed through the Euclid norm of normal vector of the boundary at the closest saddle node bifurcation point. The advantage of the proposed method is that it gets the advantages of both methods, the accuracy of the direct method and simple of Thevenin Equivalent model. Thus, the proposed method holds some promises in terms of performing the real-time voltage stability monitoring of power system. Test results of New England 39 bus system are presented to show the effectiveness of the proposed method.

• 문화기술의 융합
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• 제8권6호
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• pp.531-536
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• 2022

전 세계적으로 국가경쟁력, 효용성, 중요성 등의 이유로 메가시티가 속속 등장하고 있으며, 점차 각 국가의 중심지로 자리를 잡아가고 있다. 또한, 메가시티는 현존, 잠재적, 초국가, 비군사 등 다양한 위협에 노출될 수밖에 없다. 특히, 최근 우크라이나-러시아 전쟁에서 볼 수 있듯이 국가기반체계는 적대 및 위협세력의 주요 목표가 되고 있다. 하지만 메가시티의 막대한 규모, 다양한 위협의 양상, 한정된 자원 등을 고려할 때 모든 국가기반체계를 완벽하게 방호하는 것은 현실적으로 어렵다. 따라서 여러 국가기반체계 중 핵심노드를 식별하여 중점적으로 방호하는 접근이 필요하다. 핵심노드는 다양한 국가기반시설이 연결된 국가기반체계의 중요도가 매우 높면서도 동시에 급소에 해당한다. 이를 위해 본 연구에서는 핵심노드를 논리적·체계적으로 식별하기 위해 네트워크 이론인 노드 중심성(Centrality) 분석방법과 군사이론인 중심(Center of Gravity) 분석방법을 제시하였다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2007년도 정기 학술대회 논문집
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• pp.271-274
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• 2007

The finite element linear buckling analysis of folded plate structures using adaptive h-refinement methods is presented in this paper. The variable-node flat shell element used in this study possesses the drilling D.O.F. which, in addition to improvement of the element behavior, permits an easy connection to other elements with six degrees of freedom per node. The Box-typed structures can be analyzed using these developed flat shell elements. By introducing the variable node elements some difficulties associated with connecting the different layer patterns, which are common in the adaptive h-refinement on quadrilateral mesh, can be overcome. To obtain better stress field for the error estimation, the super-convergent patch recovery is used. The convergent buckling modes and the critical loads associated with these modes can be obtained.

• 한국통신학회논문지
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• 제34권10C호
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• pp.937-945
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• 2009

본 논문에서는 변수노드의 차수가 3인 정칙 LDPC 부호의 absorbing 집합(AS)에 대한 여러 가지 성질을 알아본다. Girth가 인 경우, 가장 작은 absorbing 집합은 AS임을 보였고, 인 경우 이 AS가 가장 작은 fully absorbing 집합임을 증명하였다. 또한 (3,5) Tanner LDPC 부호에서 오류 마루의 주원인으로 꼽히는 몇몇 absorbing 집합의 critical number를 유도하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권4호
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• pp.1562-1578
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• 2020

Vector data compression algorithm can meet requirements of different levels and scales by reducing the data amount of vector graphics, so as to reduce the transmission, processing time and storage overhead of data. In view of the fact that large threshold leading to comparatively large error in Douglas-Peucker vector data compression algorithm, which has difficulty in maintaining the uncertainty of shape features and threshold selection, a segmented Douglas-Peucker algorithm based on node importance is proposed. Firstly, the algorithm uses the vertical chord ratio as the main feature to detect and extract the critical points with large contribution to the shape of the curve, so as to ensure its basic shape. Then, combined with the radial distance constraint, it selects the maximum point as the critical point, and introduces the threshold related to the scale to merge and adjust the critical points, so as to realize local feature extraction between two critical points to meet the requirements in accuracy. Finally, through a large number of different vector data sets, the improved algorithm is analyzed and evaluated from qualitative and quantitative aspects. Experimental results indicate that the improved vector data compression algorithm is better than Douglas-Peucker algorithm in shape retention, compression error, results simplification and time efficiency.

• 한국공간구조학회논문집
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• 제14권3호
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• pp.47-56
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• 2014

This paper investigates the characteristics of unstable behaviour and critical buckling load by joint rigidity of framed large spatial structures which are sensitive to initial conditions. To distinguish the stable from the unstable, a singular point on equilibrium path and a critical buckling level are computed by the eigenvalues and determinants of the tangential stiffness matrix. For the case study, a two-free node example and a folded plate typed long span example with 325 nodes are adopted, and these adopted examples' nonlinear analysis and unstable characteristics are analyzed. The numerical results in the case of the two-free node example indicate that as the influence of snap-through is bigger; that of bifurcation buckling is lower than that of the joint rigidity as the influence of snap-through is lower. Besides, when the rigidity decreases, the critical buckling load ratio increases. These results are similar to those of the folded-typed long span example. When the buckling load ratio is 0.6 or less, the rigidity greatly increases.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 추계학술대회
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• pp.537-538
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• 2021

본 논문에서는 군집 그룹에서 위험 데이터 수집을 위한 에이전트 관리 방안에 대해 고려한다. 위험 지역에서 수집되는 위험 데이터의 경우 센서 노드의 손상으로 에이전트 임무 수행 실패에 대한 가능성이 높다. 따라서 센서 노들들에 대한 협력적 네트워크 방식을 통하여 위험 에이전트 노드에 대한 처리를 연구한다.