• ETRI Journal
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• v.41 no.6
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• pp.782-796
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• 2019

This paper presents a hierarchical framework for managing the sampling distribution of a particle filter (PF) that estimates the global positions of mobile robots in a large-scale area. The key concept is to gradually improve the accuracy of the global localization by fusing sensor information with different characteristics. The sensor observations are the received signal strength indications (RSSIs) of Wi-Fi devices as network facilities and the range of a laser scanner. First, the RSSI data used for determining certain global areas within which the robot is located are represented as RSSI bins. In addition, the results of the RSSI bins contain the uncertainty of localization, which is utilized for calculating the optimal sampling size of the PF to cover the regions of the RSSI bins. The range data are then used to estimate the precise position of the robot in the regions of the RSSI bins using the core process of the PF. The experimental results demonstrate superior performance compared with other approaches in terms of the success rate of the global localization and the amount of computation for managing the optimal sampling size.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.461-468
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• 2008

RFID technology is one of the core technologies for ubiquitous computing, and many research activities have been going on in this research area currently. Related with these researches, mobile RFID network services using mobile devices having a built-in RFID reader and mobile networks have been launched in Korea, for the first time in the world. In this paper, we propose a method to coulect ALE middleware suggested by EPCglobal and existing mobile RFID network services. Especially, a RFID code conversion method is proposed to process mobile RFID code systems within ALE middleware systems. Using the proposed method, application developers and(or) content business industries can acquire the information they want, which is filtered and refined in real-time or periodically, from mobile RFID users. So, they can Provide customized services to users by using the user preference information. In this war, the ALE middleware system can be easily extended to process mobile RFID code effectively.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.3
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• pp.99-104
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• 2003

Ad-hoc is the wireless network and consists of moving Hosts in environments which don't have a network-based Frame. Because ad-hoc is considered as broadcast network and network which has useful benefits, multicast muting protocols have been studied on ad-hoc network For this work we scrutinized ad-hoc and multicast routing protocols presented in previous works. And we presents a protocol for Ad-hoc network.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.2
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• pp.163-168
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• 2008

Navigation system based on indoor location estimation is one of the core technologies in mobile robot systems. Wireless sensor network has great potential in the indoor location estimation due to its characteristics such as low power consumption, low cost, and simplicity. In this paper we present an algorithm to estimate the indoor location of mobile robot based on wireless sensor network and fuzzy modeling. ZigBee-based sensor network usually uses RSSI(Received Signal Strength Indication) values to measure the distance between two sensor nodes, which are affected by signal distortion, reflection, channel fading, and path loss. Therefore we need a proper correction method to obtain accurate distance information with RSSI. We develop the fuzzy distance models based on RSSI values and an efficient algorithm to estimate the robot location which applies to the navigation algorithm incorporating the time-varying data of environmental conditions which are received from the wireless sensor network.

• Journal of Advanced Navigation Technology
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• v.14 no.6
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• pp.859-864
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• 2010

In the next generation system, a study on realization of Multi-Core system is in progress for applying it in multi service network. Therefore some mobile systems are expected to be appeared. These systems can support WiBro, WCDMA, CDMA, etc with single terminal. These systems have to support various FA using broadband frequency and hand over to other service network. Especially, in the telecommunication system composed of cell, the transmit power can be interference at adjacent system, has effect on system channel capacity and cell size. In this paper, we improve the unstable transmit power caused by unsettled system operation, propose the RF(Radio Frequency) Calibration method which can use the transmit power stably even during hand over between heterogeneous networks causing unstable power change. Also we used proposed method and analysed used electricity of system during hand over between heterogeneous networks.

• IEMEK Journal of Embedded Systems and Applications
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• v.3 no.4
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• pp.218-228
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• 2008

The convergence of broadcasting and telecommunication services is being accelerated by broadband networks, digital broadcasting and Web2.0. This paper describes the definition and service characteristics of IPTV as a representative of broadcasting and telecommunication convergence services. Especially, the changes of infrastructure and technology for IPTV2.0 are addressed in terms of the service features of mobility, intelligence and participation. IPTV2.0 shall be characterized by the open IPTV service based on Web2.0 and the mobile IPTV service over the heterogeneous networks employing various wireless/wired access technologies. The IP Multimedia Subsystem (IMS) and Service Delivery Platform (SDP) technologies are increasingly considered to support the personalization and openness. The mobility management technology is being evolved to provide QoS-guaranteed mobile communication services to users at anytime and anywhere. IPTV2.0 services and platforms are also anticipated to be core components to achieve knowledge-based ubiquitous society. IPTV2.0 contents are required to be integrated with the enhanced metadata to efficiently support search, selection, convergence and delivery of the contents. Moreover, those contents shall be enhanced to provide the scalable services which is adaptable to the network status and user preferences. Therefore, the networking technologies for IPTV2.0 should tightly cooperate with application services and adaptive contents. Those technologies will be developed to construct the ubiquitous content service platform considering the evolution of networks and various converged services.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.7B
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• pp.760-770
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• 2011

The existing mobility management schemes do not fully support the next generation network, which is composed of IP-based core network and various access networks. Currently, ETRI has been developing the AIMS (Access Independent Mobility Service) system which satisfies the ITU-T requirements of mobility management in the next generation network. The AIMS system is designed to provide a mobile host with a fast and reliable mobility service among heterogeneous access networks. Recently, many user devices have multiple communication interfaces, e.g., 3G and WLAN, and thus they can make two or more network connections at the same time. In this paper, we design a scheme of flow mobility, i.e., the movement of selected data flows from one access technology to another, to be applied in the AIMS system, and verify the proposed scheme through the NS-3 simulation study. From the simulation results, we can know that the proposed flow mobility scheme can utilize the network resource efficiently in the heterogeneous mobile networks.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.264-268
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• 2007

This article presents the performance evaluation case study of circuit-switched WCDMA R5MSC(Mobile Switching Center) Server and CS-MGW(Circuit Switched Media Gateway) in 3'rd generation mobile telecommunication (UMTS : Universal Mobile Telecommunication System). The presented work adopted circuit switching scenarios recommended by 3GPP(Third Generation Partnership Project) and terrestrial spectrum calculation parameters and its values defined in ITU-R M.2023 and M.1390 to do the case study on performance evaluation of circuit switched system (R5 MSC Server and CS-MGW) in WCDMA core network. This paper describes test results by using simulator which substitutes for wireless section (MS, Node-B, RNC).

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1257-1260
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• 2002

3 세대 이동통신 시스템인 UMTS/GPRS 는 모든 MS(Mobile Station)에게 인터넷 서비스를 항상 제공할 수 있도록 하는 것을 목표로 하고 있다. 그러나 최근 인터넷 사용의 증가로 인해 public IPv4 주소 부족 현상이 발생함에 따라 인터넷에 연결되어 있는 모든 MS 에게 public IPv4 주소를 할당하는데 한계가 있다. 이에 따라 3GPP의 Release 2000 IM CN(IP Multimedia Core Network) 서브 시스템에서는 멀티미디어 서비스 지원을 위해 인터넷에 연결되어 있는 모든 MS 에게 IP 를 할당할 수 있도록 IPv6 지원을 필수로 정의하고 있다. 따라서 UMTS/GPRS 에서 IPv6 를 지원할 경우 이동망과 인터넷망간의 패킷 서비스 전달을 위해 게이트웨이 기능을 수행하는 GGSN 에서 가장 큰 변화가 이루어질 것이다. 그러므로 본 논문에서는 GGSN 이 dual stack 을 지원해야하는지에 대해 살펴본 후 UMTS/GPRS 프로토콜 구조를 제안한다. 그리고 IPv6 지원을 위해 GGSN의 기능을 설계하고 GTP 메시지와 IPv6 주소 할당 방법에 대해 살펴본다.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.12
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• pp.1127-1136
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• 2004

This paper proposes a novel multicasting algorithm, called ANMAS (Ad hoc Network Multicasting with Ant System), for Mobile Ad hoc Network (MANET). The algorithm utilizes the indirect communication method of the ants via 'pheromone' to effectively obtain dynamical topology change information, generating safer multicasting paths, and adapts the well-known CBT (Core Based Tree) multicasting algorithm into the ANMAS framework with proper modificiations to make 'tolerable' multicasting group in the MANET environment. We show the efficiency and the effectiveness of ANMAS via simulation studies.