• ETRI Journal
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• 제37권2호
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• pp.262-272
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• 2015

In particular, for a practical mobile robot team to perform such a task as that of carrying out a search and rescue mission in a disaster area, the network connectivity and localization have to be guaranteed even in an environment where the network infrastructure is destroyed or a Global Positioning System is unavailable. This paper proposes the new collective intelligence network management architecture of multiple mobile robots supporting seamless network connectivity and cooperative localization. The proposed architecture includes a resource manager that makes the robots move around and not disconnect from the network link by considering the strength of the network signal and link quality. The location manager in the architecture supports localizing robots seamlessly by finding the relative locations of the robots as they move from a global outdoor environment to a local indoor position. The proposed schemes assuring network connectivity and localization were validated through numerical simulations and applied to a search and rescue robot team.

• Journal of information and communication convergence engineering
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• 제12권1호
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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.

• International Journal of Fuzzy Logic and Intelligent Systems
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• 제5권3호
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• pp.189-195
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• 2005

One of the major components of any pervasive system is its proactive behavior. Various models have been developed to provide system wide changes which would enable proactive behavior. A major drawback of these approaches is that they do not address the need to make use of existing applications without modifying the applications. To overcome this drawback, a middleware architecture called 'Concord' is proposed. Concord is based on a simple model which consists of Lookup Server and Database. The rewards for this simple model are many. First, Concord uses the existing computing infrastructure. Second, Concord standardizes the interfaces for all services and platforms. Third, new services can be added dynamically without any need for reconfiguration. Finally, Concord consists of Database that can maintain and publish the active set of available resources. Thus Concord provides a solid system for integration of various entities to provide seamless connectivity and enable proactive behavior.

• Educational Technology International
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• 제9권2호
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• pp.97-121
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• 2008

The purposes of the present study are to describe the design of mobile learning scenarios based on learning sciences theories, and to discuss implications for the future research in this area. To move beyond mere speculations about the abundant possibilities of mobile learning and to make real impact in K-12 school settings, it is critical to conduct school-based research grounded on the learning sciences theories. Towards this end, this paper describes school-based mobile learning projects conducted by a research team at the Learning Sciences Lab in Singapore, and then discusses the possibilities and challenges of mobile learning to further inform future research. Specifically, this paper explores the affordances of mobile technology, such as portability, connectivity and context-sensitivity, to design seamless learning scenarios that bridge formal and informal learning experiences. The authors present a framework for re-conceptualizing different types of learning based on physical settings and intentionality, and then describe two seamless learning scenarios, namely 3Rs and Chinatown Trail, which were implemented in one primary school in Singapore. In conclusion, the authors discuss the affordances of seamless mobile learning for enhancing one's lived experiences to build a living ecological relationship between the person and the environment, and how mobile technology can play a critical role for enabling such lived experiences.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.47-52
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• 2006

In this paper, we suggested new network architecture to provide seamless service between the cellular system and new wireless broadband network such as IEEE 802.16e, called WiBro. The interworking technologies are very important issue because mobile operator should provide service connectivity between various wireless networks based on different access technologies. Moreover a change and modification on legacy network should be minimized for providing interworking with new wireless broad-band network. We implemented proposed interworking architecture between 3G cellular network and 802.16e network to provide seamless service including interworking unit in real test environment. Also, we performed performance evaluation in hybrid network environments.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2006년도 추계학술대회 학술발표 논문집 제16권 제2호
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• pp.391-394
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• 2006

본 논문은 차세대 유비쿼터스 네트워크에서 서로 다른 운영체제 사용자 간의 공통 인터페이스를 유연하게 지원할 수 있는 방법을 제시하였다. 각기 다른 명령이나 메타포, 운영체제에 기반하는 이미지, 아이콘들처럼 공용으로 사용할 수 있는 데이터 부분을 각기 코드값화하여 프록시 서버에서 처리함으로써, 한정된 대역안에서의 대역폭 사용 효율증가와 중복전송 데이터를 최소화할 수 있다. 또한 차세대 이기종 장치간의 지속적인 연결성을 지원하기 위한 공통 사용자 인터페이스를 제공 방안으로 활용될 수 있겠다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2008년도 추계종합학술대회 B
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• pp.66-69
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• 2008

IP계층에서의 이동성 지원에 대한 연구가 활발히 진행되어 IETF에서 MIPv6에 대한 표준화가 진행되었다. MIPv6는 이동 노드가 망과 망 사이를 이동할 때, 서비스에 대한 연결성을 유지하여 끊김 없는 통신을 가능하게 해주며, 이러한 방법을 핸드오버라고 한다. IEEE 802.21에서는 MIH(Media Independent Handover)라는 끊김 없는 핸드오버를 위한 방법을 표준화했다. MIH는 하위 레이어와 상위 레이어에서의 핸드오버를 위해 세 가지 서비스를 사용하였으며, 본 논문에서는 기존의 MIH에 두 가지 모드를 적용하여 네트워크 시뮬레이터에서 듀얼 모바일 호스트와 싱글 모바일 호스트의 성능 평가를 수행하였다.

• Journal of information and communication convergence engineering
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• 제14권2호
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• pp.89-96
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• 2016

In mobile communication, there are various types of handoff for the support of all forms of mobility. Proxy mobile IPv6 (PMIPv6) enables local network-based mobility management of a mobile node without any effect of mobility-related signaling. Recently, PMIPv6 has been considered for supporting mobility management in LTE/SAE-based mobile networks. To support seamless mobility in heterogeneous mobile networks, the overall cost of handoffs needs to be minimized and the procedure should be guaranteed to be secure. However, the reduction of the authentication cost has not been fully investigated to provide seamless connectivity when mobile users perform a handoff between the PMIPv6 domains. This paper proposes secure pre-authentication schemes, completing an authentication procedure before performing a handoff, for a fast handoff in PMIPv6. Analytic models have been used for measuring the authentication latency and for the overhead cost analysis. In addition to providing fast authentication, the proposed pre-authentication schemes can prevent threats such as replay attacks and key exposure.

• 한국통신학회논문지
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• 제29권7A호
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• pp.781-785
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• 2004

Mobile IP maintains Internet connectivity while Mobile Hosts moving from one Internet attachment point to another. However, Mobile If is not appropriate for seamless mobility. Some micromobility protocols were proposed to complement Mobile IP by offering fast and seamless handoff control in limited geographical areas. In this paper, a new scheme, based on path prediction and resource reservation, is proposed to reduce the handoff latency by trying to eliminate the link setup time for fast handoff in all-IP wireless networks. Analytical results show that the proposed scheme offers shorter handoff delay and can improve the handoff efficiency.

• International Journal of Internet, Broadcasting and Communication
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• 제14권1호
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• pp.25-30
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• 2022

Since Tim Berners-Lee introduced the idea of the web to the world in the late 1980s, the way information is produced, accessed and used has been constantly changing. This was once again an era of upheaval after Apple's Steve Jobs introduced the smartphone to the world in the mid-2000s. Before the advent of smart devices, web browsing was mainly done using desktops. After the advent of this device, the era of solving almost all human needs with a small PC in the palm of your hand has arrived. The necessity of seamless connectivity between devices, which are constantly emerging and evolving, asks our attention more than ever. In this study, we will discuss a case of design and development of a national open access website, which is optimized for dynamic online user behaviors with diverse devices. Our goal is to provide one true web for people to use in their environment. Device makers need to provide products identical to the desktop environment as much as possible. Service providers should also provide services optimized for each device in hyper-connected environments. Providing a web, optimized for user's online context, will eventually result in a sustainable user experience.