• Journal of KIISE:Information Networking
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• v.33 no.4
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• pp.299-309
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• 2006

In Mobile ad hoc networks, AODV is one of the famous on-demand routing protocol, which use the routing tables in the nodes if possible, or Route Discovery Process (RDP) is triggered to find a new route. However increasing the traffic of RDP causes dropping of the network performance in the large size of ad hoc networks. In this paper, we propose a novel routing protocol, named as AOZDV (Ad hoc On-demand Zone and Distance-Vector Routing), which enhances the AODV protocol with zone routing. AOZDV creates a Zone with neighbor nodes of the source/destination using traffic and power information, and utilizes Destination-Vector Table for internal routing in the Zone. We show by simulations that AOZDV can reduce the occurrence rate of route fail and RDP caused by route fail compared to existing routing protocols such as DSR and AODV.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.9A
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• pp.758-766
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• 2011

Cooperative communications are adopted as a promising solution to achieve high data rate over large areas in the future 40 wireless system and the relay station (RS) is the key concept in cooperative communications. However, most existing works in this area focus only on optimal RS selections. In addition, there are only few works consider another crucial issue: how many relay stations we need to place. Only when the number of relay stations is defined, the relay station selection can be performed well. In this paper we derive a formula which describes the impact of varying number of RS on end-to-end link throughput assuming a clustering scheme which is based on Voronoi tessellation. In addition to mathematical analysis on the feasibility of the formula, we also examine its performance through a set of simulations under the Erceg path loss model. Simulation results verify that the link throughput gain of our proposed scheme is promising.

• KIPS Transactions on Software and Data Engineering
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• v.2 no.5
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• pp.311-318
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• 2013

Recently, there have been many studies on RFID-based SCM. Yet, studies of synchronizing errors caused by tracking logistics information in supply chain, and activating & monitoring RFID infra is still insufficient. Also, there is no case of developing the intelligent SCM system enabling total monitoring and controlling RFID Infra by applying these technologies. Logistics information synchronization based Smart SCM model is intelligent supply chain service model to monitor the status of the RFID equipments in supply chain and the synchronization of the logistics process in each logistics point through one integrated view, as well as to react instantly by providing the information to help the various decision makings, when the emergency occurs. By adopting global logistics standard, RFID related standard specification, EPCIS standard, and SSI middleware platform, this model provides the domestic standard specification.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.11
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• pp.2135-2142
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• 2007

Mobile device will be able to use the various contents from the advancement of the wireless Internet and mobile device manufacture technique. Each devices is HTTP headers about under using provides device information to contents provider in the provide the contents. However, There is no standard for device information provided, so interoperability problems, because external contents using mobile phone companies to provide the device information in a different way. International Organization for Standard OMA UAProf about under using it solved interoperability problems from outside. However, in using the UAProf can not provide for the complete device information, because MMS support information, smart card support, information and support for external storage is not specified. Thus, In this paper, we designed UAProf in base which provides the contents which has become optimize to the mobile device of domestic environment the mobile device description language which expresses device information which is necessar, and it used to design and implementation of the Contents Adaptation System.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.147-151
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• 2014

With the advent of tiny and inexpensive computer systems like Raspberry Pi, it has become possible to construct an experimental environment of MANETs (Mobile Ad hoc Networks) at a relatively low cost. In this paper, we implement a node of MANETs with a Raspberry Pi equipped with two 802.11 wireless LAN cards and dynamic routing software running on it. In an outdoor MANETs environment with moving mobile nodes automatically rebuilding broken routes, we conducted a real-time video streaming experiment over the MANET. The video stream is transmitted from a node with a video camera installed on it to another node through the route established dynamically. Each node is equipped with a display device, with which the current status of the node can be checked out. We also implemented software that automatically collects data stored in each node and analyzes the performance of the MANETs. Through this experiment, we could evaluate the performance of realistic video streaming service in a MANETs environment.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.2
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• pp.213-224
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• 2012

The integrated core network architecture and various mobile subscriber behavior can result in a significant increase of signaling load inside the evolved packet core network proposed by 3GPP in Release 8. Consequently, an authentication signaling analysis can provide insights into reducing the authentication signaling loads and latency, satisfying the quality-of-experience. In this paper, we evaluate the signaling loads in the EPS architecture via analytical modeling based on the renewal process theory. The renewal process theory works well, irrespective of a specific random process (i.e. Poisson). This paper considers various subscribers patterns in terms of call arrival rate, mobility, subscriber's preference and operational policy. Numerical results are illustrated to show the interactions between the parameters and the performance metrics. The sensitivity of vertical handover performance and the effects of heavy-tail process are also discussed.

• Industry Promotion Research
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• v.8 no.4
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• pp.177-186
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• 2023

Modern society is operated based on the internet, wireless networks, and digital devices to the extent that it is called a digital society. In particular, as most of financial transactions, information movement, and commercial activities are based online, various social problems and side effects related to this are increasing rapidly. Representative examples include industrial espionage activities and leakage of industrial technology, and social problems such as illegal goods trade such as drugs using online and online gambling are increasing to a serious level. These digital-based social problems cannot be solved only by the activities and capabilities of judicial institutions such as police and prosecutors. Now that the private investigation market is open, active intervention using them is necessary. To this end, it is necessary to actively cultivate private investigator's ability to investigate and collect evidence in relation to digital social and criminal problems. In addition, each private investigation education institution or association should actively invest and research this.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.11
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• pp.2218-2229
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• 2015

Recently Wi-Fi Alliance defined Wi-Fi direct, which can communicate through a direct connection between the mobile device anytime, anywhere. In Wi-Fi direct, all devices are categorized by group of owner (GO) and client. Since portability is emphasized in Wi-Fi direct devices, it is essential to control the energy consumption of a device very efficiently. In order to avoid unnecessary power consumed by GO, Wi-Fi direct standard defines two power management schemes: Opportunistic power saving scheme and Notice Of Absence (NOA) scheme. But, these two schemes do not consider the traffic pattern, so we cannot expect high energy efficiency. In this paper, we suggest an algorithm to enhance the energy efficiency of Wi-Fi direct power saving, considering the characteristics of multimedia video traffic. Proposed algorithm utilizes the statistical distribution for the size of video frames and adjusts the length of awake interval dynamically. Also, considering the inter-dependency among video frames, the proposed algorithm assigns priorities to video frames and ensures that a video frame with high priority is transmitted with higher probability than other frames with low priority. Simulation results shows that the proposed method outperforms the traditional NOA in terms with average delay and energy efficiency.

• Journal of KIISE:Information Networking
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• v.34 no.1
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• pp.1-15
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• 2007

Increase in the wireless mobile network users brings the issue of mobility management into the Virtual Private Network (VPN) services. We propose a provider edge (PE)-based provider provisioned mobile VPN mechanism, which enables efficient communication between a mobile VPN user and one or more correspondents located in different VPN sites. The proposed mechanism not only reduces the IPSec tunnel overhead at the mobile user node to the minimum, but also enables the traffic to be delivered through optimized paths among the (mobile) VPN users without incurring significant extra IPSec tunnel overhead regardless of the user's locations. The proposed architecture and protocols are based on the BGP/MPLS VPN technology that is defined in RFC24547. A service provider platform entity named PPVPN Network Server (PNS) is defined in order to extend the BGP/MPLS VPN service to the mobile users. Compared to the user- and CE-based mobile VPN mechanisms, the proposed mechanism requires less overhead with respect to the IPSec tunnel management. The simulation results also show that it outperforms the existing mobile VPN mechanisms with respect to the handoff latency and/or the end-to-end packet delay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6A
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• pp.609-616
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• 2011

The Delay/Disruption Tolerant Network (DTN) is a network designed to operate effectively using the mobility and storage of intermediate nodes under no end-to-end guaranteed network. This new network paradigm is well-suited for networks which have unstable path and long latencies (e.g. interplanetary network, vehicular network). In this paper, we first found that each taxi has its own regularly visiting area and define this property as spatial regularity. We analyze 4000 taxi trace data in Shanghai and show the existence of spatial regularity experimentally. Based on a spatial regularity in urban environment, we present a new DTN routing method. We introduce a Weighted Center (WC) which represents spatial regularity of each node. Through the association with evenly distributed access points (APs) in urban environment, most of vehicles get their grid locations and calculate their WCs. Since our routing method only uses neighbors' WCs for building routing paths, it can be regarded as distributed and practical protocols. Our experiments involving realistic network scenarios created by the traces of about 1500 Shanghai taxies show that our routing method achieves the higher performance compared to ECT, LET by 10%~110%.