• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3468-3473
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• 2013

Conditions that overlay multicast tree must satisfy for the real-time application system of a video-conference, an internet broadcasting is two things. First, the degree of nodes in a tree must be proper value. Second, the diameter of the multicast tree, distance between longest two users should be short. If the path between two users in the tree is long, the delay time in data transmission between two users great. So, it is not suitable to the application system such as video-conferences. In this paper, the cost of the dijkstra algorithm calculate with proposed score-function through checking the extra bandwidth, the delay and the requested bandwidth. It is composed the tree through the dijkstra algorithm.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5487-5495
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• 2012

The important issue that applies security key are secure rekeying, processing time and cost reduction. Because of sensor node's limited energy, energy consumption for rekeying affects lifetime of network. Thus it is necessary a secure and efficient security key management method. In this paper, I propose an energy efficient group-based cluster key management (EEGCK) in the large scale sensor networks. EEGCK uses five security key for efficient key management and different polynomial degree using security fitness function of sector, cluster and group is applied for rekeying and security processing. Through both analysis and simulation, I also show that proposed EEGCK is better than previous security management method at point of network energy efficiency.

• Journal of KIISE:Computer Systems and Theory
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• v.35 no.8
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• pp.361-371
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• 2008

In this paper, the hypercube, hyperpetersen networks, whose degree is increasing in accordance with expansion of number of node and complete binary tree are one-to-one embedded into peterson-torus(PT) network which has fixed degree. The one-to-one embedding has less risk of overload or idle for the processor comparative to one-to-many and many-to-one embedding. For the algorithms which were developed on hypercube or hyperpetersen are used for PT network, it is one-to one embedded at expansion ${\doteqdot}1$, dilation 1.5n+2 and link congestion O(n) not to generate large numbers of idle processor. The complete binary tree is embedded into PT network with link congestion =1, expansion ${\doteqdot}5$ and dilation O(n) to avoid the bottleneck at the wormhole routing system which is not affected by the path length.

• Journal of KIISE
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• v.44 no.1
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• pp.78-83
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• 2017

Finding the densest subgraphs from social networks, such that people in the subgraph are in a particular community or have common interests, has been a recurring problem in numerous studies undertaken. However, these algorithms focused only on finding the single densest subgraph. We suggest a heuristic algorithm of the bottom-up type, which finds the densest subgraph by increasing its size from a given starting node, with the repeated addition of adjacent nodes with the maximum degree. Furthermore, since this approach matches well with parallel processing, we further implement a parallel algorithm on the MapReduce framework. In experiments using various graph data, we confirmed that the proposed algorithm finds the densest subgraphs in fewer steps, as compared to other related studies. It also scales efficiently for many given starting nodes.

• The Journal of the Korea Contents Association
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• v.9 no.8
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• pp.49-56
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• 2009

In this paper, we propose a method of energy level, node degree and selection information based CDS(Connected Dominating Set) construction algorithm for more efficient routing in ad-hoc wireless networks. Constructing CDS in ad-hoc wireless network, it is necessary to make more efficient algorithm that is faster, more simple and has low power consumption. A CDS must be minimized because nodes in the CDS consume more energy in order to handle various bypass traffics than nodes outside the set. It is better not to reconstruct CDS after constructing the most efficient CDS. To overcome this problem, we proposed the CDS construction algorithms based on EL+ND+Sel method. We compared and estimated the performance in each situation of EL + ND and EL + ND + Sel.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.12
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• pp.105-114
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• 2019

The goal of this study is to quantitatively evaluate the effects of the additional construction of urban railroads. To this end, 1) establish accessibility as a measure of quantitative evaluation of construction effects; 2) select the 'Integration' of Space Syntax as a quantifiable indicator of accessibility; 3) represent the Seoul railroads as a network; 4) calculate the 'Integration' form the network before and after the additional construction of the urban railroads. By calculating the change of the 'Integration' of the individual nodes and the change of the sum of the 'Integration' of given zones, the change in accessibility of a particular node and the change in accessibility of a particular region were calculated. After analyzing the change in accessibility in nodes and areas as well, it was confirmed that the additional construction of urban railroads was improving accessibility as a whole of Seoul. It was also identified that there was a degree of difference in the extent of the accessibility change for the different areas. It is particularly noteworthy that changes occur in the accessibility ranking. While certain regions were improving relative rankings, others fell in rank. With this finding, it could be argued that active consideration of the areas in which the relative decline occurs is needed when the planned urban railroad is being built.

• Structural Engineering and Mechanics
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• v.66 no.3
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• pp.329-341
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• 2018

This paper considers the smooth receding contact problem between a homogeneous half-plane and a composite laminate composed of an inhomogeneously coated elastic layer. The inhomogeneity of the elastic modulus of the coating is approximated by an exponential function along the thickness dimension. The three-component structure is pressed together by either a concentrated force or uniform pressures applied at the top surface of the composite laminate. Both semianalytical and finite element analysis are performed to solve for the extent of contact and the contact pressure. In the semianalytical formulation, Fourier integral transformation of governing equations and boundary conditions leads to a singular integral equation of Cauchy-type, which can be numerically integrated by Gauss-Chebyshev quadrature to a desired degree of accuracy. In the finite element modeling, the functionally graded coating is divided into homogeneous sublayers and the shear modulus of each sublayer is assigned at its lower boundary following the predefined exponential variation. In postprocessing, the stresses of any node belonging to sublayer interfaces are averaged over its surrounding elements. The results obtained from the semianalytical analysis are successfully validated against literature results and those of the finite element modeling. Extensive parametric studies suggest the practicability of optimizing the receding contact peak stress and the extent of contact in multilayered structures by the introduction of functionally graded coatings.

• Journal of Gastric Cancer
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• v.1 no.4
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• pp.197-201
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• 2001

Purpose: There are variants of gastric cancer assoclated with predominantly peritoneal spread of with haematogenous metastases. Perioperative intraperitoneal chemotherapy as an adjuvant to surgery is considered as a rational therapeutic modality to prevent peritoneal spread. We evaluated the influence of early postoperative intraperitoneal chemotherapy on the prognosis of resectable advanced gastric cancer. Materials and Methods: From 1990 to 1995, 246 patients with biopsy proven advanced gastric cancer were enrolled in the study. Among them 123 patients received early postoperative intraperitoneal mitomycin C and 5-fluorouracil. The survival rate was calculated using by the Kaplan-Meier method and was compared using the log-rank test according to 13 clinico-pathologic factors. Multivariate analysis was performed with the Coxproportional hazards model. Results: Gastric resection plusearly postoperative intraperitoneal chemotherapy showed an improved survival rate as compared to surgery alone ($54.1\%\;versus\;40.3\%;$ P=0.0325). Depth of tumor invasion, degree of regional lymph vode metastasis, distant metastasis, tumor size, tumor location, extent of gastric resection, and curability of surgery significantly influenced survival. When a multivariate analysis was performed, depth of tumor invasion, lymph node metastasis, early postoperative intraperitoneal chemotherapy, curability of surgery, and extent of gastric resection emerged as the statistically significant and independent prognostic factors. Conlusion: Early postoperative intraperitoneal chemotherapy is one of the independent prognostic indicators of resectable advanced gastric cancer.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.6
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• pp.1439-1450
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• 1995

Bellows is a familiar component in piping systems as it provides a relatively simple means of absorbing thermal expansion and providing system flexibility. In routine piping flexibility analysis by finite element methods, bellows is usually considered to be straight pipe runs modified by an appropriate flexibility factor; maximum stresses are evaluated using a corresponding stress concentration factor. The aim of this study is to develop a bellows finite element, which similarly includes more complex shell type deformation patterns. This element also does not require flexibility or stress factors, but evaluates more detailed deformation and stress patterns. The proposed bellows element is a 3-D, 2-noded line element, with three degrees of freedom per node and no bending. It is formulated by including additional 'internal' degrees of freedom to account for the deformation of the bellows corrugation; specifically a quarter toroidal section of the bellows, loaded by axial force, is considered and the shell type deformation of this is include by way of an approximating trigonometric series. The stiffness of each half bellows section may be found by minimising the potential energy of the section for a chosen deformation shape function. An experiment on the flexibility is performed to verify the reliability for bellows finite element.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.59-68
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• 2015

Traditional structure analysis method is based on numerical matrix analysis to use the geometries consisting of the structure. The characteristics require a lot of computer memories and computational time. To avoid these weaknesses, new approach to analyze truss structure was suggested by adopting topological load redistribution method. The axial forces to be not structurely analyzed yet against outside loads were redistributed by using nodal equation of equilibrium randomly at each node without constructing global matrix. However, this method could not calculate the axial forces if structure is statically indeterminate due to degree of many indeterminacies. Therefore, to apply the method suggested in this research, all redundancies of truss structure were replaced by unit loads. Each unit load could make the deformation of a whole structure, and a superposition method was finally adopted to solve the simultaneous equations. The axial forces and deflections agreed with the result of commercial software within the relative error of 1 %, whereas in the case that the axial forces are relatively very smaller than others, the relative errors were increased to 2 %. However, as the values were small enough not to be considered, it was practically useful as a structural analysis model. This model will be used for structural analysis of truss type of large structure such as agricultural farming facility.