• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.9
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• pp.3572-3593
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• 2015

This article investigates the topology control problem in the space information network (SIN) using a hierarchical autonomous system (AS) approach. We propose an AS network topology control (AS-TC) algorithm to minimize the time delay in the SIN. Compared with most existing approaches for SIN where either the purely centralized or the purely distributed control method is adopted, the proposed algorithm is a hybrid control method. In order to reduce the cost of control, the control message exchange is constrained among neighboring sub-AS networks. We prove that the proposed algorithm achieve logical k-connectivity on the condition that the original physical topology is k-connectivity. Simulation results validate the theoretic analysis and effectiveness of the AS-TC algorithm.

• Korean Journal of Geomatics
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• v.4 no.2
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• pp.53-57
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• 2004

Due to the traffic congestion and public-oriented transportation policies of Seoul, public transportation is receiving attention and being used increasingly. However, current transport routes configuration is showing unbalanced accessibility throughout the city area creating differences in time, expenses and metal burden of users who travel the same distances. One of the reasons is that transport route planning has been partially empirical and non-quantitative tasks due to lack of relevant methods for assessing the complexity of the transport routes. This paper presents a method to compute the connectivity of public transport system based on the topological structure of the network of transport routes. The main methodological issue starts from the fact that the more transfers take place, the deeper the connectivity becomes making that area evaluated as less advantageous as for public transport accessibility. By computing the connectivity of each bus or subway station with all others in a city, we can quantify the differences in the serviceability of city areas based on the public transportation. This paper is based on the topological interpretation of the routes network and suggests an algorithm that can automate the computation process. The process is illustrated using a simple artificial network data built in a GIS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.11B
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• pp.1133-1141
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• 2009

In this paper, we present a distributed fault-tolerant topology control protocol that configure a wireless sensor network to achieve k-connectivity and (k+1)-coverage. One fundamental issue in sensor networks is to maintain both sensing coverage and network connectivity in order to support different applications and environments, while some least active nodes are on duty. Topology control algorithms have been proposed to maintain network connectivity while improving energy efficiency and increasing network capacity. However, by reducing the number of links in the network, topology control algorithms actually decrease the degree of routing redundancy. Although the protocols for resolving such a problem while maintaining sensing coverage were proposed, they requires accurate location information to check the coverage, and most of active sensors in the constructed topology maintain 2k-connectivity when they keep k-coverage. We propose the fault-tolerant topology control protocol that is based on the theorem that k-connectivity implies (k+1)-coverage when the sensing range is at two times the transmission range. The proposed distributed algorithm does not need accurate location information, the complexity is O(1). We demonstrate the capability of the proposed protocol to provide guaranteed connectivity and coverage, through both geometric analysis and extensive simulation.

• Journal of Korean Society for Geospatial Information Science
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• v.12 no.2 s.29
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• pp.73-77
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• 2004

Due to the traffic congestion of the city and public transportation-oriented policies in large cities, public transportation is receiving attention and being used increasingly. However, relatively less research on the design and distribution of public transportation network and limitations in quantitative approaches have made implementation and operation practically difficult. Over- or under-supply of transportation routes caused unbalanced connectivity among areas and, thus, differences in time, expenses and metal burden of users traveling the same distances. On the other hand, the Space Syntax theory, originally designed to calculate the connectivity of urban or architectural spaces, helps generate quantitative connectivity of whole space simply based on the spacial structure. This study modified the original Space Syntax algorithm to fit the public transportation problem and showed how it is applied to a transportation network by creating an artificial GIS network.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.5
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• pp.49-59
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• 2015

In this research, the connectivity status between natural environment (forests and rivers) and urban parks in view of ecological networks in a city is evaluated and on the basis of these evaluation results, a future connectivity enhancing recommendations are suggested. As a result, the 96.8% of the connectivity role of the neighborhood parks were core or connected parks and as in terms of the ecological pattern on the outer park, 84.1% of the case neighborhood parks were connected to the ecological element at least one side. Therefore, it can be expected to play a role as corridor that enables the direct connection with the natural environment if the connection plan is well established. As a result of connectivity evaluation of the parks, inside of the parks had low ecological element overall and had low connectivity, outside of the parks had 1.5 times more of low connectivity parks than high connectivity parks, and had similar disconnections such as facilities(fence, soundproof walls, breast walls, etc.), developments(roads, apartment complexes, industrial complexes, etc.), or poor greens regardless of the neighborhood with the ecological elements. To increase the connectivity of ecological network, the cities already built shall secure primarily green territory where can connect with the isolated park due to the surrounding with the developing areas and when planning for new cities or residential complexes, it shall establish a connection plan with the nearby at the beginning.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.4
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• pp.436-445
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• 2011

As automation systems become intelligent and autonomous for productibility, industrial networks (fieldbuses) and network-based devices are essential components of intelligent manufacturing systems. However, there are obstacles for the wide acceptance of the network-based devices such as smart sensor and network-based actuator. First, there exist numerous fieldbus protocols that a network-based device should be able to support. Second, the whole network-based device has to be replaced when only the sensor of the module fails. In order to overcome these obstacles, a smart sensor/actuator is implemented as two units; one responsible for network communication and the other for sensor/actuator operations using IEEE 1451.0 standard. This paper presents a structure of the 1451.0-based smart sensor with multiple connectivity function designed by CANopen.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.7
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• pp.1230-1251
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• 2011

This document specifies a new IPv6 deployment protocol called CHANC, which stands for Configuring Hosts to Auto-detect (IPv6, IPv6-in-IPv4, or IPv4) Network Connectivity. The main part is an application level tunneling protocol that allows Internet Service Providers (ISPs) to rapidly start deploying IPv6 service to their subscribers whom connected to the Internet via IPv4-only access networks. It carries IPv6 packets over HTTP protocol to be transmitted across IPv4-only network infrastructure. The key aspects of this protocol are: offers IPv6 connectivity via IPv4-only access networks, stateless operation, economical solution, assures most firewall traversal, and requires simple installation and automatic configuration at customers' hosts. All data packets and routing information of the IPv6 protocol will be carried over the IPv4 network infrastructure. A simple application and a pseudo network driver must be installed at the end-user's hosts to make them able to work with this protocol. Such hosts will be able to auto-detect the ISP available connectivity in the following precedence: native IPv6, IPv6-in-IPv4, or no IPv6 connectivity. Because the protocol does not require changing or upgrading customer edges, a minimal cost in the deployment to IPv6 service should be expected. The simulation analysis showed that the performance of CHANC is pretty near to those of native IPv6, 6rd, and IPv4 protocols. Also, the performance of CHANC is much better than that of D6across4 protocol.

• Science of Emotion and Sensibility
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• v.22 no.1
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• pp.35-44
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• 2019

Individuals with problematic hypersexual behavior (PHB) evince the inability to control sexual impulses and arousal. Previous studies have identified that these characteristics are related to structural and functional changes in the brain region responsible for inhibitory functions. However, very little research has been conducted on the functional connectivity of these brain areas during the resting state in individuals with PHB. Therefore, this study used functional magnetic resonance imaging devices with the intention of identifying the deficit of the functional connectivity in the executive control network in individuals with PHB during the resting state. Magnetic resonance imaging data were obtained for 16 individuals with PHB and 19 normal controls with similar demographic characteristics. The areas related to the executive control network (LECN, RECN) were selected as the region of interest, and the correlation coefficient with time series signals between these areas was measured to identify the functional connectivity. Between groups analysis was also used. The results revealed a significant difference in the strength of the functional connectivity of the executive control network between the two groups. In other words, decreased functional connectivity was found between the superior/middle frontal gyrus and the caudate, and between the superior/middle frontal gyrus and the superior parietal gyrus/angular gyrus in individuals with PHB. In addition, these functional Connectivities related to the severity of hypersexual behavior. The findings of this study suggest that the inability to control sexual impulses and arousal in individuals with PHB might be related to the reduced functional connectivity of executive control circuits.

• Journal of Environmental Impact Assessment
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• v.32 no.6
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• pp.503-515
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• 2023

The disconnection and fragmentation of ecological spaces that occur during the development process pose a significant threat to biodiversity. Urban center areas with high development pressure are particularly susceptible to low connectivity due to a scarcity of ecological space. This issue tends to be more pronounced in larger cities.To address this challenge, continuous efforts are needed to assess and improve the current state of ecological space connectivity at the level of individual projects and urban management. However, there is a lack of discussion regarding the analysis and improvement of ecological connectivity in metropolitan cities In line with this objective, this study evaluated the connectivity of ecological spaces in the city centers of Seoul, Busan, Daegu, Incheon, Gwangju, Daejeon, and Ulsan. The evaluation revealed that city centers exhibited lower connectivity of ecological spaces compared to their peripheries or the overall city. In addition, in the ecological network analysis that reflected regional characteristics, such as the species distribution model conducted on Daejeon, 510 optimal paths connecting forests of more than 1ha were derived. This study is significant as an example of deriving an ecological network based on regional characteristics, including quantitative figures necessary for establishing goals to improve urban ecological connectivity and biodiversity. It is anticipated that the results can be utilized to propose directions for enhancing ecological connectivity in environmental impact assessments or urban management and to establish an evaluation framework.

• Journal of information and communication convergence engineering
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• v.12 no.1
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• pp.26-32
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• 2014

Vehicular-to-anything (V2X) technology is attractive for wireless vehicular ad-hoc networks (VANETs) because it allows for opportunistic choice of a vehicular protocol between vehicular-to-vehicular (V2V) and vehicular-to-infrastructure (V2I) communications. In particular, achieving seamless connectivity in a VANET with nearby network infrastructure is challenging. In this paper, we propose a density-based opportunistic broadcasting (DOB) protocol, in which opportunistic connectivity is carried out by using the nearby infrastructure and opposite vehicles for solving the problems of disconnection and long end-to-end delay times. The performance evaluation results indicate that the proposed DOB protocol outperforms the considered comparative conventional schemes, i.e., the shortest path protocol and standard mobile WiMAX, in terms of the average end-to-end delay, packet delivery ratio, handover latency, and number of lost packets.