• KSII Transactions on Internet and Information Systems (TIIS)
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• v.4 no.6
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• pp.1063-1079
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• 2010

Vehicle ad hoc networks (VANET) are one of the most important technologies to provide various ITS services. While VANET requires rapid and reliable transmission, packet transmission in VANET is unstable because of high mobility. Many routing protocols have been proposed and assessed to improve the efficiency of VANET. However, topology-based routing protocols generate heavy overhead and long delay, and position-based routing protocols have frequent packet loss due to inaccurate node position. In this paper, we propose a position-based routing repair algorithm to improve the efficiency of VANET. This algorithm is proposed based on the premise that AODV (-PGB) can be used effectively in VANET, if the discovery, maintenance and repair mechanism of AODV is optimized for the features of VANET. The main focus of this algorithm is that the relay node can determine whether its alternative node exits and judge whether the routing path is disconnected. If the relay node is about to swerve from the routing path in a multi-hop network, the node recognizes the possibility of path loss based on a defined critical domain. The node then transmits a handover packet to the next hop node, alternative nodes and previous node. The next node repairs the alternative path before path loss occurs to maintain connectivity and provide seamless service. We simulated protocols using both the ideal traffic model and the realistic traffic model to assess the proposed algorithm. The result shows that the protocols that include the proposed algorithm have fewer path losses, lower overhead, shorter delay and higher data throughput compared with other protocols in VANET.

• Journal of Internet Computing and Services
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• v.15 no.4
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• pp.111-118
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• 2014

In mobile sensor networks, a large number of sensor nodes with battery powered are deployed randomly in a region. They monitor the environmental states and transmit data to its neighboring nodes. For mobile sensor networks, It is needed to maintain the connectivity autonomously among nodes as the sensor node moves. However, the existing works have focused on the energy savings in the fixed sensor networks. A specific algorithm considering node mobility is required in the mobile sensor networks. Along with energy efficiency, the transmission delay should be considered. In this paper, we propose an autonomous configuration scheme and a node scheduling algorithm when a moving node joins into the existing network. Through simulations, we show a superior performance of the proposed algorithm to the existing protocol.

• Journal of the Korean Geographical Society
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• v.45 no.6
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• pp.735-747
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• 2010

This study explains a turning to being cultured and geography management to get closer to popularization and specialization of geography, for which based on the assumption that they are for development of knowledge. It adopts the idea of human's geographical nature to solve the dualism which geography is referred as science and art. An object geographer studies is homogeneous, temporal as well as identifical and individual. To adopt human's geographical nature causes to human's geographical investigation, and uniting positivism to humanism. It deduces from the Bible and Evolutionism that it is characteristic of mobility, adaptabilty, connectivity, ideality, and hybridity. Geographical concepts is based on the fact that it can be applied to geographical research theme. Popularization of geography has to relate to being cultural, and specialization of geography has to relate to geography management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.10
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• pp.2014-2025
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• 2015

Wireless Sensor Networks (WSNs) are special network which has purpose of usage for gathering information of certain area and observing situation. WSNs consist of small nodes with sensing event such as temperature, movement or certain objects. The sensor has the capabilities to collect data and route data back to the sink. The sensors route data either to other sensors or back to a sink in one direction. That is, traditional WSNs communicate asymmetrically. However, under the new paradigm of the Internet of Things (IoTs) or Cyber Physical system (CPS), WSNs have potential to be used as important area. So, more research is necessary to communicate with each moving objects symmetrically in WSNs. In this paper, we proposed symmetric communication scheme among mobile objects in wireless sensor network. Simulation results show that our scheme is superior th the existing ones in terms of energy consumption and transmission success ratio.

• Journal of Digital Contents Society
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• v.14 no.2
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• pp.223-233
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• 2013

This paper studied the effects of service quality and system quality that affect customer's satisfaction and continued usage intention regarding mobile network conditions. The hypotheses and research models were completed using research factors of service quality(reactivity, empathy) and system quality(connectivity, ease of use, channel-mobility) borrowed from previous studies on DMB and IPTV. The hypotheses and research models were verified through experiments and surveys. The key finding showed that customer's expectation on service quality and system quality under fast network(Wifi) was higher than that of under slow network(3G). Furthermore, it showed that users react more sensitive to service quality than to system quality such as network speed. Based on the results, this study has the implication for expanding the understanding of the factors used in previous DMB and IPTV studies by applying them in N-screen domain.

• ETRI Journal
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• v.40 no.1
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• pp.39-50
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• 2018

More people prefer using rail traffic for travel or for commuting owing to its convenience and flexibility. The railway scenario has become an important communication scenario in the fifth generation era. The communication system should be designed to support high-data-rate demands with seamless connectivity at a high mobility. In this paper, the channel characteristics are studied and modeled for the railway tunnel scenario with straight and curved route shapes. On the basis of measurements using the "Mobile Hotspot Network" system, a three-dimensional ray tracer (RT) is calibrated and validated for the target scenarios. More channel characteristics are explored via RT simulations at 25.25 GHz with a 500-MHz bandwidth. The key channel parameters are extracted, provided, and incorporated into a 3rd-Generation-Partnership-Project-like stochastic channel generator. The necessary channel information can be practically realized, which can support the link-level and system-level design of the communication system in similar scenarios.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.1
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• pp.125-129
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• 2010

Stateless computing supports a mobility of computing environment easily. It is becoming a major technology for securing personal user's information on shared computing environment. With the advance of virtualization technology and cloud computing, stateless computing is an essential part of personal computing environment connectivity (user's setting and data is stored in remote server or some storage, and it can be restored at any computing environment) In this paper, we propose uPC player that supports stateless computing execution environment on Windows. uPC player provides Windows operating system to user by using an uPC OS virtualization module. In this paper, we leverage how uPC player is designed and implemented for supporting a stateless computing execution environment. uPC player provides a desktop switch between host-system execution environment and uPC virtual execution environment. And it needs just one second for loading uPC virtual execution environment by using OS virtualization-based technique.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.517-520
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• 2009

Healthcare application system has been actively researched to apply WSN technology to healthcare area with a mobile sensor node of low cost, low power, and small size. Sensor node has the problem for transmission range of RF power and time delay of the wireless routing connectivity between sensor nodes. In this paper, we proposes a new method utilizing mobile sensor nodes with relay sensor nodes for quick network routing changing using query technique in healthcare system. A query processor to control and manage the routing changing of sensor nodes in a wireless sensor network was designed and implemented. The user's PC transmits the beacon message which will change the quick link routing according to activity status of patient in wireless sensor network. We describe the implementation for query protocol that is very effective of power saving between sensor nodes.

• 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.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.2
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• pp.182-194
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• 2023

Traffic impact assessment plays a crucial role in resolving traffic issues that may arise during the implementation of urban and transportation projects. However, reported results diverge, presumably because the items reviewed differ. In this study, we analyze traffic improvement measures approved for traffic impact assessment, identify key items, and present items that should be included in assessments. Specifically, TF-IDF and N-gram analysis and text mining were performed with focus on urban development projects approved in Gyeonggi Province. The results obtained show that keywords associated with newly established transportation infrastructure, such as roads and intersections, were essential assessment items, followed by the locations of entrances and exits and pedestrian connectivity. We recommend that considerations of the items presented in this study be incorporated into future traffic impact assessment guidelines and standards to improve the consistency and objectivity of the assessment process.