• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.7A
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• pp.770-777
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• 2007

Smaller cell size in the micro-cell or pico-cell structure brings about more frequent hand-overs between cells, and higher speed movement of the mobile terminal makes short the permissible time interval for executing these hand-over procedures. In this situation the hand-over failure may occur or some packets may be lost during the hand-over. Moreover a rapid degradation of throughput is triggered by packet re-transmission for compensating such errors. The QoS (Quality of Services) of mobile multimedia applications with higher bits rate requirements and higher speed mobility are severely affected by even shot service interruption. This paper proposes a new hand-over scheme to provide seamless services in the next generation mobile communication systems. Simulation is done to evaluate the performance of the proposed scheme based on its hand-over failure rate and packet loss rate.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.2
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• pp.15-23
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• 2013

In this paper, we propose a session management and control architecture for N-Screen services, which enable users to change devices and transfer contents among user's devices during service by session transfer and split. In N-Screen services, users may have multiple devices with different attribute such as screen resolution, CPU capability and access network interfaces. Also, since users may change devices during service, or one user may use multiple stream, N-Screen services need to enable the user to share and transfer contents across N-Screen devices. We introduce the management and control servers to provide session split over user multiple devices and session continuity while changing device. Furthermore, the proposed architecture provides the device capabilities aware session continuity. In addition, the proposed scheme minimizes the session transfer delay and content server processing load. We present results that show the effectiveness and usefulness of proposed architecture.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.6
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• pp.2680-2696
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• 2018

The collaborative content caching system is an effective solution developed in recent years to reduce transmission delay and network traffic. In order to decrease the service end-to-end transmission delay for future 5G ultra-dense networks (UDN), this paper proposes a novel service migration method that can guarantee the continuity of service and simultaneously reduce the traffic flow in the network. In this paper, we propose a service migration optimization model that minimizes the cumulative transmission delay within the constraints of quality of service (QoS) guarantee and network condition. Subsequently, we propose an improved firefly algorithm to solve this optimization problem. Simulation results show that compared to traditional collaborative content caching schemes, the proposed algorithm can significantly decrease transmission delay and network traffic flow.

• Journal of the Korea Society of Computer and Information
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• v.21 no.1
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• pp.49-57
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• 2016

In this paper we propose the resource allocation scheme for the overlaid macro-femtocell networks, which considers the type of handovers such as the inter-macrocell, macrocell-to-femtocell, femtocell-to-macrocell, or inter-femtocell in order to guarantee Quality of Service (QoS) and expand the accommodation capacity. Our proposed scheme takes into account the movement of mobile terminals, the QoS degradation, or the load control which trigger handovers in the overlaid networks, before it allocates resources dynamically. Moreover it considers QoS requirements of realtime or non-realtime mobile multimedia services such as video communication, Video on Demand (VoD) and dataa services. Simulation results show that our scheme provides better performances than the conventional one with respect to the outage probability, data transmission throughput and handover failure rate.

• Korea Journal of Hospital Management
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• v.16 no.1
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• pp.27-49
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• 2011

This study tried to examine the antecedents of antecedents of trust and customer response at the healthcare service. A total of 230 patient' data were used with a structural equation analysis. They were verified by covariance modeling, using SPSS 18.0 and AMOS 5.0program. Trust is significantly affected by the three factors. Doctors' professionalism and effort of relationship continuity have a positive impact on trust simultaneously. Also, brand reputation have a positive impact on trust simultaneously. But, Trust is not significantly affected by tangibles. And, Trust has a not positive impact on the word of mouth(WOM). Satisfaction has a positive impact on the repurchase and WOM. Repurchase has a positive impact on the WOM.

• Journal of Distribution Science
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• v.22 no.9
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• pp.107-117
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• 2024

Purpose: This research aims to contribute to the search for strategies on innovation in chatbot services in airline distribution industry. Personal and systemic characteristics of chatbot were derived together. The extended technology acceptance model theory was applied. The effects of perceived ease of use, usefulness, and intention to use chatbot from the user's perspective were empirically analyzed. Research design, data and methodology: Through an online survey, 309 people who have experience using chatbot services in airline distribution industry responded. AMOS 18.0 was used to analyze the data. Results: The hypothesis that personal characteristics will positively influence perceived ease and perceived usefulness was tested. Self-efficacy and user's innovativeness were shown have a significant effect on both perceived ease and perceived usefulness. System characteristics present a positive effect on perceived ease and perceived usefulness was tested. Consistency and familiarity were found to affect perceived ease and perceived usefulness. Perceived ease of use and perceived usefulness show a positive effect on intention to continue using chatbot service. Conclusions: When building an airline chatbot service in airline distribution industry, it is necessary to consider systematic characteristics, ease of use, and usability. It provided practical implications in that it have a significant impact on users' intention to use.

• Proceedings of the KSR Conference
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• 2011.05a
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• pp.109-116
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• 2011

In this paper, we investigate the scheme to improve the position accuracy using GNSS(Global Navigation Satellite System). Then we configure the real-time DGPS environment with use of NTRIP currently being in service on the DGNSS central office of MLTM(Ministry of Land and Transportation). And we verify the improvement of position accuracy and the continuity of GPS correction data through the DGPS test in Chungbuk line and Joongang line.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2768-2774
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• 2011

In this paper, we investigate the methods to improve the position accuracy using DGNSS(Differential Global Navigation Satellite System). Then we configure the real-time DGNSS environment with use of GPS and MSAS as SBAS(Satellite Based Augmentation System) currently being in service by Japan. And we verify the improvement of position accuracy and the continuity of GPS correction data through the realtime DGNSS test in Joongang line, Kyungbu line, Honam line.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.620-623
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• 2008

Home service networked system gets more its fault chances, which are fault by the external factors, network fault, home appliance fault, and so on. Moreover, user may want to pay no attention to a sequence of complex or nervous maintenance jobs for system fault management. Therefore, home management system needs the function of home service recovery for fault home device. For this, this paper manages to design home network control log, and proposes the method for securing the home device service continuity analyzing home device service log in the point of fault.

• Journal of Advanced Navigation Technology
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• v.10 no.2
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• pp.128-137
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• 2006

Recently, the combination of WLAN and 3G wireless technologies will make MMS service more ubiquitous, bringing benefits to both service providers and their customers. To realize seamless MMS service over WLAN and CDMA2000 networks, we design novel seamless interworking architecture by reusing the existing standards and network elements at the same time. Based on the proposed seamless interworking architecture, we also present seamless notification architecture and seamless handover architecture that can't be possible within current MMS reference architecture. This paper will make a contribution for service providers to provide their customers with seamless MMS service over WLAN and CDMA2000 networks.