• Proceedings of the KIEE Conference
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• 2000.11b
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• pp.389-391
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• 2000

A representation technique of a given track topology is required by many software applications in railway technology such as signalling system simulator. To achieve these, the concept of double vertex graph architecture is proposed. These are composed of pairs of vertices and node between the single vertices. Double vertex graph architecture can be understood as a extension of classical graphs. In developed railway signalling simulation software, it is shown that track topology can be represented by proposed algorithm in a efficient way. Especially it makes sure that these are suitable technique for representing and implementing of switch, routes which can be introduced some mistake in classical graph algorithm.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4B
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• pp.309-316
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• 2012

The compensation algorithm for localization using the least-squires method in NLOS(Non Line of Sight) environment is suggested and the performance of the algorithm is analyzed in this paper. In order to improve the localization correction rate of the moving node, 1) the distance value of the moving node that is moving as an constant speed is measured by SDS-TWR(Symmetric Double-Sided Two-Way Ranging); 2) the location of the moving node is measured using the triangulation scheme; 3) the location of the moving node measured in 2) is compensated using the least-squares method. By the experiments in NLOS environment, it is confirmed that the average localization error rates are measured to ${\pm}1m$, ${\pm}0.2m$ and ${\pm}0.1m$ by the triangulation scheme, the Kalman filter and the least-squires method respectively. As a result, we can see that the localization error rate of the suggested algorithm is higher than that of the triangulation as average 86.0% and the Kalman filter as average 16.0% respectively.

• The KIPS Transactions:PartC
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• v.19C no.2
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• pp.83-90
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• 2012

MANET(Mobile Ad-Hoc Network) has a weakness from a security aspect because it operates where no wired network is built, which causes the exposed media, dynamic topology, and the lack of both central monitoring and management. It is especially difficult to detect and mitigate a malicious node because there is not a mediator which controls the network. This kind of malicious node is closely connected to the routing in the field of study of Ad-Hoc security. Accordingly this paper proposes the method on how to enhance the security for the safe and effective routing by detecting the malicious node. We propose MBC(Identification technition of Malicious Behavior node based on Collaboration in MANET) that can effectively cope with malicious behavior though double detecting the node executing the malicious behavior by the collaboration between individual node and the neighbor, and also managing the individual nodes in accordance with the trust level obtained. The simulation test results show that MBC can find the malicious nodes more accurately and promptly that leads to the more effectively secure routing than the existing method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.345-348
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• 2017

MTTDL, a measure for reliability of distributed storage system, is analyzed for the case when double node repair is possible and compared with the single node repair cases.

• Journal of Bio-Environment Control
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• v.10 no.3
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• pp.181-186
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• 2001

During the growth of fruit vegetables such as pepper, cucumber and tomato, there are light deficiency under the plant canopy. This study was conducted to clarify the effect of light diffusion film on the stem growth, canopy, flowering and fruiting of green pepper in greenhouse. The transmittance of total solar radiation into greenhouse under woven and double films were 90% and 75% of polyethylene film. And the transmittance of photosynthetically active radiation into greenhouse under woven and double films were 96% and 81% of polyethylene film. However, the light diffusions under woven, double and polyethylene films were 46%, 31% and 9%, respectively. The plant height under polyethylene film covered greenhouse was 96.9% cm, taller than those under woven and double films by 6.5, 13.9 cm. And the third node length under woven film covered greenhouse was 8.6 cm, shorter than those under double and polyethylene films by 2.5, 5.7 cm. Also the first branch angle under woven film covered greenhouse was 61.0$^{\circ}$, larger than those under double and polyethylene films by 2.3, 10.3$^{\circ}$. But there was no clear difference in the node numbers among the covering materials. The rate of curved and sterile fruit under woven film covered greenhouse was smaller than those under double and polyethylene films by 4.6, 5.5% and 1.2, 3.6%. But the contents of vitamin C showed no difference among the covering materials and plant densities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.4
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• pp.711-719
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• 1994

This paper deals with the development of an efficient algorithm which can consider the bond-slip effect in numerical analysis of reinforced concrete structures. Unlike the classical bond-link or bond-zone element using double nodes, the proposed model is considering the bond-slip effect without taking double nodes by incorporation of the equivalent steel stiffness. Moreover after calculation of nodal displacements, the deformation of steel at each node can be found out through the back-substitution technique from first up to final steel element using a governing equation constructed based on the equilibrium at each node of steel and the compatibility condition between steel and concrete.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.5
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• pp.38-45
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• 2012

Finding shortest paths on time dependent networks is an important task for scheduling and routing plan and real-time navigation system in ITS. In this research, one-to-one time dependent shortest path algorithms based on link flow speeds on urban networks are proposed. For this work, first we select three general shortest path algorithms such as Graph growth algorithm with two queues, Dijkstra's algorithm with approximate buckets and Dijkstra's algorithm with double buckets. These algorithms were developed to compute shortest distance paths from one node to all nodes in a network and have proven to be fast and efficient algorithms in real networks. These algorithms are extended to compute a time dependent shortest path from an origin node to a destination node in real urban networks. Three extended algorithms are implemented on a data set from real urban networks to test and evaluate three algorithms. A data set consists of 4 urban street networks for Anaheim, CA, Baltimore, MD, Chicago, IL, and Philadelphia, PA. Based on the computational results, among the three algorithms for TDSP, the extended Dijkstra's algorithm with double buckets is recommended to solve one-to-one time dependent shortest path for urban street networks.

• The KIPS Transactions:PartC
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• v.15C no.4
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• pp.281-288
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• 2008

Recently, the advance of multimedia hardware has fostered the development of wireless multimedia sensor network which is able to ubiquitously obtain multimedia content such as image or audio from the environment. The multimedia data which has several characteristics such as large size and correlation between the data requires reliability in transmission. However, the existing solution which take the focus on the efficiency of network mainly, is not appropriate to transmit the multimedia data. In the paper, we proposes a reliable asynchronous image transfer protocol, RAIT. RAIT applies double sliding window method in node-to-node image tansfer to prevent the packet loss caused by network congestion. The double sliding window consists of one sliding window for the receiving queue, which is used for prevention of packet loss caused by communication failure between nodes and the other sliding window for the sending queue which prevents the packet loss caused by network congestion. the routing node prevents the packet loss and guarantees the fairness between the nodes by scheduling the packets based on the image non-preemptively. The RAIT implements the double sliding window method by cross layer design between RAIT layer, routing layer, and queue layer. The experiment shows that RAIT guarantees the reliability of image transmission compared with the existing protocol.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.4
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• pp.2223-2242
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• 2019

Distance Vector-Hop (DV-Hop) algorithm is widely used in node localization. It often suffers the wormhole attack. The current researches focus on Double-Wormhole-Node-Link (DWNL) and have limited attention to Multi-Wormhole-Node-Link (MWNL). In this paper, we propose a security DV-Hop algorithm (AMLDV-Hop) to resist MWNL. Firstly, the algorithm establishes the Neighbor List (NL) in initialization phase. It uses the NL to find the suspect beacon nodes and then find the actually attacked beacon nodes by calculating the distances to other beacon nodes. The attacked beacon nodes generate and broadcast the conflict sets to distinguish the different wormhole areas. The unknown nodes take the marked beacon nodes as references and mark themselves with different numbers in the first-round marking. If the unknown nodes fail to mark themselves, they will take the marked unknown nodes as references to mark themselves in the second-round marking. The unknown nodes that still fail to be marked are semi-isolated. The results indicate that the localization error of proposed AMLDV-Hop algorithm has 112.3%, 10.2%, 41.7%, 6.9% reduction compared to the attacked DV-Hop algorithm, the Label-based DV-Hop (LBDV-Hop), the Secure Neighbor Discovery Based DV-Hop (NDDV-Hop), and the Against Wormhole DV-Hop (AWDV-Hop) algorithm.

• Advances in aircraft and spacecraft science
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• v.3 no.3
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• pp.351-366
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• 2016

Macroperforations improve the sound absorption performance of porous materials in acoustic cavities and in waveguides. In an acoustic cavity, enhanced noise reduction is achieved using porous materials having macroperforations. Double porosity materials are obtained by filling these macroperforations with different poroelastic materials having distinct physical properties. The locations of macroperforations in porous layers can be chosen based on cavity mode shapes. In this paper, the effect of variation of macroporosity and double porosity in porous materials on noise reduction in an acoustic cavity is presented. This analysis is done keeping each perforation size constant. Macroporosity of a porous material is the fraction of area covered by macro holes over the entire porous layer. The number of macroperforations decides macroporosity value. The system under investigation is an acoustic cavity having a layer of poroelastic material rigidly attached on one side and excited by an internal point source. The overall sound pressure level (SPL) inside the cavity coupled with porous layer is calculated using mixed displacement-pressure finite element formulation based on Biot-Allard theory. A 32 node, cubic polynomial brick element is used for discretization of both the cavity and the porous layer. The overall SPL in the cavity lined with porous layer is calculated for various macroporosities ranging from 0.05 to 0.4. The results show that variation in macroporosity of the porous layer affects the overall SPL inside the cavity. This variation in macroporosity is based on the cavity mode shapes. The optimum range of macroporosities in poroelastic layer is determined from this analysis. Next, SPL is calculated considering periodic and nodal line based optimum macroporosity. The corresponding results show that locations of macroperforations based on mode shapes of the acoustic cavity yield better noise reduction compared to those based on nodal lines or periodic macroperforations in poroelastic material layer. Finally, the effectiveness of double porosity materials in terms of overall sound pressure level, compared to equivolume double layer poroelastic materials is investigated; for this the double porosity material is obtained by filling the macroperforations based on mode shapes of the acoustic cavity.