• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.10a
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• pp.268-296
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• 2005

Given the growing expectations on the value and application of mobile office, we need to understand the factors which affect its successful use and implementation. We in this paper present a parsimonious model which integrates the IS success model and the TAM. The main feature of the model is that it allows one to explore the role of mobility of mobile office systems in determining the level of system usage and dependence. Although mobility is the key property of any mobile system, there is little research effort exerted to understand how mobility affects the traditional IS factors such as perceived ease of use and usefulness. In addition to the system usage, this model also uses dependence as the dependent variable. This is expected to provide richer understanding of the study context. We collected survey data from 1,614 field service workers of a major domestic electronic company. They use PDAs to retrieve information regarding the specifics of the customer service requests and to report what has been done for each service job. The results from SEM analysis show that mobility improves the perceived ease of use which then leads the field service workers to depend more on the PDA systems. Interestingly enough, however, the workers’ satisfaction does not cause more frequent use of the system.

• Journal of Communications and Networks
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• v.8 no.4
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• pp.451-460
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• 2006

Since low earth orbit (LEO) satellite constellations have important advantages over geosynchronous earth orbit (GEO) systems such as low propagation delay, low power requirements, and more efficient spectrum allocation due to frequency reuse between satellites and spotbeams, they are considered to be used to complement the existing terrestrial fixed and wireless networks in the evolving global mobile network. However, one of the major problems with LEO satellites is their higher speed relative to the terrestrial mobile terminals, which move at lower speeds but at more random directions. Therefore, handover management in LEO satellite networks becomes a very challenging task for supporting global mobile communication. Efficient and accurate methods are needed for LEO satellite handovers between the moving footprints. In this paper, we propose a new seamless handover management scheme for LEO satellites (SeaHO-LEO), which utilizes the handover management schemes aiming at decreasing latency, data loss, and handover blocking probability. We also present another interesting handover management model called satellite mobility pattern based handover management in LEO satellites (PatHO-LEO) which takes mobility pattern of both satellites and mobile terminals into account to minimize the handover messaging traffic. This is achieved by the newly introduced billboard manager which is used for location updates of mobile users and satellites. The billboard manager makes the proposed handover model much more flexible and easier than the current solutions, since it is a central server and supports the management of the whole system. To show the performance of the proposed algorithms, we run an extensive set of simulations both for the proposed algorithms and well known handover management methods as a baseline model. The simulation results show that the proposed algorithms are very promising for seamless handover in LEO satellites.

• Journal of KIISE:Information Networking
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• v.35 no.3
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• pp.183-191
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• 2008

In this paper, we propose Stream Control Transmission Protocol(SCTP) proxy which supports making an SCTP connection from a Corresponding Node(CN) to a Mobile Node(MN). Recently, mobility support in transport layer is proposed, which provides mobility in end-to-end way using the extension of SCTP. Mobile SCTP can provide handover to all applications that use SCTP as a transport protocol. However, current SCTP does not include independent location management service and can not make connection from a CN to a MN without assistance of other mobile protocols. To solve this problem, Proposed SCTP proxy interoperates with generic location management service and performs an address transformation to forward connection set up messages to the MN. Using the proposed proxy, SCTP can provide a complete mobility support including a connection setup to the MN and maintaining an existing connection.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.14 no.6
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• pp.75-84
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• 2014

In order to solve the problems such as overload, single point of failure, non-optimized data path, and network scalability in conventional central mobility management protocols, distributed mobility management schemes have been continually studied in and around the IETF. In this paper, a network-based partially-distributed mobility management mechanism, pDMMv6, is suggested and the performance comparison with traditional protocols such as PMIPv6 and MIPv6 is made through simulation under the various user traffic environment. The simulation results include UDP packet delivery ratio, end-to-end packet delay, binding delay for registration signaling, CPU utilization in each node, and response delays in several server-client TCP applications such as web browsing, e-mail, telnet remote login, FTP file up/down-load, and database access.

• Journal of Korean Society of Transportation
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• v.35 no.1
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• pp.50-62
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• 2017

As the use of private cars increases along with the technological advancement in the automobile industries and their capabilities to supply, a wide range of issues are followed including the increase in traffic congestion costs, pavement damages and more. In spite of consistent effort to resolve such urban traffic problems, the modal share rate of private cars continuously increases, thus it is becoming more important to explore the ways to enable drivers to take reasonable measures, in self-motivated manner, by taking part of the transportation demand management policy rather than to rely on the strict enforcement of control policy. Considering that the urban transportation infrastructures are in much better shape than before, it is necessary to implement Mobility Management (MM) that induces reasonable usage of private cars by promoting the change in one's consciousness and behavior through communication. Hence, the research studies the factors that influence the mobility through the survey targeting the citizens of Busan on their awareness on the former transportation demand management policy, to explore the ways to motivate the citizens' involvement in reducing the use of private cars as a measure of Mobility Management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.78-87
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• 2015

Content-Centric Networking(CCN) is a new networking paradigm to search for the routing information needed to find a data from the content name, unlike conventional IP networks. In CCN, the mobility management, one of the CCN challenges, is consists of consumer mobility and content provider mobility. Among both, in the case of the content provider mobility, it requires too much overhead and time to update routing information on the corresponding routers. In this paper, we propose Popularity-based Pushing CCN(PoPCoN) which considers the content popularity to support effective mobility of content provider in CCN. Our proposed algorithm shortens content download time for the consumer and reduces the network overhead during mobility as compared to the existing approaches.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.6B
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• pp.592-599
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• 2011

Proxy Mobile IPv6 (PMIPv6) is the network-based mobility management protocol that network supports the mobility of mobile node (MN) on behalf of the MN. In PMIPv6, a multi-homed MN can connect to the PMIPv6 domain by using only one interface even though it has multiple interfaces. It would be efficient when such a multi-homed MN connects to the PMIPv6 domain by using all of its interfaces. If such a multi-homed MN utilizes all of its interfaces, flow mobility can be provided that the MN handovers one or more flows from one interface to another without re-establishing session. In this paper, we propose the flow-based mobility management protocol by considering the intention of the user. The Router Advertisement (RA) message is used in order for the PMIPv6 domain to inform that the MN can utilize the flow mobility. The proposed mechanism is evaluated by analyzing signaling overhead and handover latency, and the numerical results show that the performance is affected by mobility speed of the MN and the failure probability of the wireless link.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1223-1228
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• 2004

The study for ubiquitous computing infra is proceeding actively, it make possible to use service and access network anywhere, anytime because of wire/wireless communication technology and progress of hardware. Domestically, study for the network mobility support technology which is the key technology for future ubiquitous computing realization have progressed, but that is insufficient. Especially, there is no study for independent mobility support study about railway wireless network. So, this study propose network mobility management technology for mobile network infra in railway and proper network model in train.

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.241-243
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• 2005

The study for ubiquitous computing infra is proceeding actively, it make possible to use service and access network anywhere, anytime because of wire/wireless communication technology and progress of hardware. Domestically, study for the network mobility support technology which is the key technology for future ubiquitous computing realization have progressed, but that is insufficient. Especially, there is no study for independent mobility support study about railway wireless network. So, this study propose network mobility management technology for mobile network infra in railway and proper network model in train.

• The KIPS Transactions:PartA
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• v.9A no.4
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• pp.413-420
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• 2002

It it essential to get the exact location information of products for a warehouse management. It is very hard, however, to know the location of products which change their location in warehouse frequently This causes the effective warehouse management to be almost impossible. In this paper, we suggest a new location management system for such a SKU(Stock Keeping Unit) with high mobility. The system is composed of RFID (Radio Frequency IDentification), a management terminal with wireless LAN, mobile devices (Cellular Phone & PDA), and a central management system. As a model of a SKU with high mobility, we selected a used-car stored in a large-scale warehouse. We designed and implanted used-car location management system. After analyzing the operations of each position in used-car warehouse where the system will run, we implemented each function. This research shows that an embedded system with wireless LAN is able to know the status of coming in and cut and location of a SKU with high mobility in warehouse very accurately in real time. Therefore, it makes the warehouse to be controlled systematically.