• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.625-628
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• 2011

Dynamic sensor network(DSN) technology which is based on swarming flight type air node offers analyzed and acquired information on target data gathered by air nodes in rotation flight or 3 dimension array flight. Efficient operation of dynamic sensor network based on air node is possible when problems of processing time, data transmission reliability, power consumption and intermittent connectivity are solved. Delay tolerant network (DTN) can be a desirable alternative to solve those problems. DTN using store-and-forward message switching technology is a solution to intermittent network connectivity, long and variable delay time, asymmetric data rates, and high error rates. However, all processes are performed at the bundle layer, so high power consumption, long processing time, and repeated reliability technique occur. DSN based on swarming flight type air node need to adopt store-and-forward message switching technique of DTN, the cancelation scheme of repeated reliability technique, fast processing time with simplified layer composition.

• Journal of Satellite, Information and Communications
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• v.12 no.4
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• pp.42-49
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• 2017

Delay- and Disruption-Tolerant Network (DTN) has been considered as a key technology to overcome main challenges in interplanetary communications such as an intermittent connectivity and high bit error rates. The lack of end-to-end connectivity between source and destination results in long and variable delays and data loss, hence the Internet Protocols cannot operate properly in such environments because it requires an end-to-end connectivity. The DTN, which utilizes 'store-and-forward' message passing scheme between nodes, can overcome the lack of end-to-end connectivity in Interplanetary Network (IPN). In this paper, DTN is applied to 3-hop relay IPN, where messages are transmitted from Earth ground station to Lunar lander through Earth satellite and Lunar orbiter. ONE simulator is used to reflect the real environment of IPN and an efficient resource management method are analyzed to guarantee the message delivery by optimizing a message TTL (Time to Live), buffer size and message fragmentation.

• Journal of Information Science Theory and Practice
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• v.5 no.3
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• pp.61-70
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• 2017

This study investigated the use of e-journals by health researchers in the Nigerian Institute of Medical Research (NIMR). A descriptive survey method was adopted for the study and a questionnaire was used for data collection. The study population was comprised of fifty-four (54) respondents who are health researchers in the institute. The data collected were presented and analyzed using tables, frequency distribution, simple percentages, and charts. The result of the study revealed that all the respondents are aware of the availability of e-journals and attest to making use of them. The study revealed that electronic journals were mostly used for the purpose of conducting research work and the PDF format was preferred for downloading e-journals. However, it was observed that low Internet connectivity and intermittent electricity supply constitute a major obstacle to the use of e-journals. The study, therefore, recommended that the institute's management invest more resources on network connectivity, particularly its bandwidth, and ensure reliable power supply.

• 전기의세계
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• v.60 no.11
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• pp.56-63
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• 2011

In the face of global warming and resource depletion, a smart grid has been suggested as one way of contributing to abating the environment problems and increasing energy efficiency. Smart grids utilize renewable energy which has intermittent and irregular output power depending on weather conditions. In order to maintain stability and reliability of the power system, smart grids need to have complementary measures for the possible unstable system conditions. Cogenerating systems such as Combined Heat and Power(CHP) can be one good solution as it has capability of instantly increasing or decreasing output power. Therefore, this paper investigates the connectivity between Combined Heat and Power systems and smart grid technologies. The smart grid national roadmap formulated by South Korea Ministry of Knowledge and Economy and 'IEC Smart Grid Standardization Roadmap' are analyzed to extract related components of the smart grid for the CHP connection. Also, case studies on demonstration projects for smart grids with CHP systems completed or currently being implementing in the world are presented.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1223-1236
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• 2014

With the extension of wireless technology, vehicular ad hoc networks provide important services for the dissemination of general data and emergency warnings. However, since, the vehicle topology frequently changes from a dense to a sparse network depending on the speed of the moving vehicles and the time of day, vehicular ad hoc networks require a protocol that can facilitate the efficient and reliable dissemination of emergency messages in a highly mobile environment under dense or intermittent vehicular connectivity. Therefore, this paper proposes a new vehicular broadcast protocol, called BL-CAST, that can operate effectively in both dense and sparse network scenarios. As a low overhead multi-hop broadcast protocol, BL-CAST does not rely on the periodic exchange of beacons for updating location information. Instead, the location information of a vehicle is included in a broadcast message to identify the last rebroadcasting vehicle in an intermittently connected network. Simulation results show that BL-CAST outperforms the DV-CAST protocol in terms of the end-to-end delay, message delivery ratio and network overhead.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.4
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• pp.151-160
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• 2009

While portable and wireless devices are pouring, a new network technology is needed as a breakthrough. The new network technology features large delays, intermittent connectivity, and absence of an end-to-end path from sources to destinations. A network which has one of those characteristics is called DTNs(Delay Tolerant Networks). The main 4 routing methods have been researched so far in extream environment. In this paper, we look into the reliability of DTMNs(Delay Tolerant Mobile Networks) in several different situations, and propose an algorithm that selects a positive routine by sending the only information of its position when making a connection to a detected node. We simulate the proposed algorithm here in DTN using ONE simulator. As a result, it shows that the algorithm reduces the number of message transmission each node.

• Journal of the Korea Society of Computer and Information
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• v.26 no.3
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• pp.69-75
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• 2021

Limitation of the TCP/IP network technology included in the vehicle communication is due to the frequent mobility of the vehicle, the increase in intermittent connection requirements, and the constant presence of the possibility of vehicle hacking. VNDN technology enables the transfer of the name you are looking for using textual information without the need for vehicle identifiers like IP/ID. In addition, intermittent connectivity communication is possible rather than end-to-end connection communication. The data itself is the subject of communication based on name-based forwarding using two types of packets: Interest packet and Data packet. One of the issues to be solved for the realization of infotainment services under the VNDN environment is the traffic explosion caused by data broadcasting. In this paper, we analyze and compare the existing technologies to reduce the data broadcast storm. Through this, we derive and analyze the requirements for presenting the best data mitigation technique for solving the data explosion phenomenon in the VNDN environment. We expect this paper can be utilized as prior knowledge in researching improved forwarding techniques to resolve the data broadcast explosion in connected vehicles over NDN.

• KIISE Transactions on Computing Practices
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• v.24 no.3
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• pp.145-150
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• 2018

Forwarding in opportunistic networks shows low performance because there may be no connecting paths between the source and the destination nodes due to the intermittent connectivity. Currently, social network analysis has been researched. Specifically, similarity is one of methods of social networks analysis. In this paper, we propose forwarding schemes based on representative similarities, and evaluate how much the forwarding performance increases. As a result, since the forwarding schemes are based on similarities, these schemes only forward messages to nodes with higher similarity as relay nodes, toward the destination node. These schemes have low network traffic and hop count while having stable transmission delay.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.6
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• pp.285-292
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• 2017

There are technological, operational and environmental constraints at tactical edge, which are disconnected operation, intermittent connectivity, and limited bandwidth (DIL), size, weight and power (SWaP) limitations, ad-hoc and mobile network, and so on. To overcome these limitations and constraints, we use service-oriented architecture (SOA) based technologies. In our research, we propose a hierarchical mission service model that supports service-oriented mission planning and execution in order for a commander to operate various SW required for mission in battlefield environment. We will also implement development tools that utilize the workflow technology and semantic capability-based recommendation and apply them to combat mission scenarios to demonstrate effectiveness.

• Journal of the Korea Society for Simulation
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• v.15 no.3
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• pp.31-37
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• 2006

To achieve the efficient performance within a mobile grid considering the intermittent network connectivity and non-dedicated heterogeneous mobile devices, this paper suggests the scheduling algorithm of job allocation as a viable solution. The suggested scheduling algorithm has two core functions, the prediction of response time for task processing and the identification of the optimal number of mobile devices to process the mobile grid applications. This scheduling algorithm suggests the numerical formulas to calculate the network latency considering the effects of heterogeneous non-dedicated mobile system in wireless network environments. Also we evaluate the performance of mobile grid system using the processing the distributed applications in implemented mobile grid environments.