• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.911-925
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• 1996

Emerging service classes need an error model which efficiently satisfies the requirements for each media and application. However limited flexibility in the error control has been provided. Therefore we propose a new error control model which applies error control scheme per media flexibly with respect to ETL(Error Tolerance Leverl) and delay. In order to select the error control scheme in this model, the attributes of media(i.e., ETL, isochronism), the attributes of application(i.e., delay) and environment parameters(i.e., packet loss ration, network types, connection modes of the application) are considered as effect factors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.12C
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• pp.273-279
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• 2001

This paper describes a design and implementation of ISDN system on a chip which provides ISDN service and used to develop a low-price multimedia communication terminal. This ISDN SOC is an ISDN system control chip which has 32bit RISC processor, and it includes ISDN S interface transceiver, G.711 voice CODEC, PC interface for data communication, ISDN protocol which includes Q.931 call control protocol and internet protocol. It provides good solution to develope ISDN terminal equipment and ISDN terminal adaptor which connected with basic rate interface, because it minimize external peripheral devices.

• Journal of Satellite, Information and Communications
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• v.8 no.2
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• pp.22-28
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• 2013

In this paper, new LBS (location based service) are proposed using conventional DMB (digital multimedia/mobile broadcasting) system. LBS applications are proposed that can be suitable for the subway and ground transportation based on S-DMB (satellite-DMB) and T-DMB (terrestrial-DMB) respectively. In the shaded area such as subway, the broadcasting signal transmitted from the satellite of S-DMB system should be retransmitted by the earth repeater called the gap filler and each gap filler has its own identification value called the gap filler ID which introduces the area in which the gap filler was installed. Therefore, the LBS can be implemented by using the gap filler ID of S-DMB on the subway in which the GPS (global positioning system) can't be received. Unlike the LBS on the subway, the combination of T-DMB and DGPS (differential GPS) will be introduced as a way for ground transportation. Generally, DGPS has been designed to compensate the position value calculated from the GPS signal so that positioning error of about 1 meter can be obtained by using DGPS information. T-DMB system transmitting DGPS signal will be expected to be commercial in Korea and, if using DGPS information transmitted through T-DMB network, LBS with more precise positioning than GPS alone can be implemented in the ground vehicles.

• Journal of Information Processing Systems
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• v.11 no.4
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• pp.509-527
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• 2015

Wireless Video Sensor Networks (WVSNs) have become a leading solution in many important applications, such as disaster recovery. By using WVSNs in disaster scenarios, the main goal is achieving a successful immediate response including search, location, and rescue operations. The achievement of such an objective in the presence of obstacles and the risk of sensor damage being caused by disasters is a challenging task. In this paper, we propose a fault tolerance model of WVSN for efficient post-disaster management in order to assist rescue and preparedness operations. To get an overview of the monitored area, we used video sensors with a rotation capability that enables them to switch to the best direction for getting better multimedia coverage of the disaster area, while minimizing the effect of occlusions. By constructing different cover sets based on the field of view redundancy, we can provide a robust fault tolerance to the network. We demonstrate by simulating the benefits of our proposal in terms of reliability and high coverage.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.344-351
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• 2004

This paper describes a modeling of service composition manager based on TINA (Telecommunication Information Networking Architecture). The service composition function is mainly motivated by the desire to easily generate new service using existing services from retailers or third party service providers. The TNA-C (Consortium) specification for the service composition does not include the detailed composition procedures and its object models. In this paper, we propose a model of components for the service composition, which adapts a static composition feature in a single provider domain To validate the proposed modeling, we implemented prototype service composition function, which combines two multimedia services; a VOD (Video On Demand) service and a VCS (Video Conference Service) service. As a result, we obtain the specification of the detailed composition architecture between a retailer domain and a third-party service provider domain.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.505-509
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• 2006

Recently, wireless Internet service has become generalized, and required the user authentication of a mobile hosts and QoS. However, time required for user authentication during handoff Processes between a wireless LAN system and mobile hosts is long, and is unsuitable for real-time communication and multimedia applications. In this paper. we improved the existing system in order to reduce a lead time of user authentication as they extended a Fast Inter-AP handoff. We use a Mechanism to assume a confidence degree with bases by the time that stayed at individual wireless LAN systems in order to reduce the handoffs. The experiment network shows that it decreases communication load, and improves communication QoS.

• The KIPS Transactions:PartC
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• v.15C no.1
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• pp.51-60
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• 2008

Micro-mobility protocols have been developed to reduce the control message overhead due to movements of mobile nodes. With the spread of mobile devices, services using mobile nodes are increasing and multicast services are becoming more important in providing multimedia services. In this paper we propose a new multicast protocol suitable for micro-mobility environments. The proposed protocol is designed to maintain optimal multicast routing paths and continue to provide multicast services without disruption in spite of frequent handoffs due to movements of mobile nodes. We used simulation to evaluate the proposed protocol, compared its performance with existing multicast protocols for mobile environments including bi-directional tunneling, remote subscription, and MMA, and observed that the proposed protocol exhibited better performance in terms of transmission success ratio and overhead on the network.

• The KIPS Transactions:PartD
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• v.16D no.5
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• pp.801-808
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• 2009

According to development of internet and an increase in demand of multimedia contents, the contents industry is being developed. However, they are served same contents in the limited environment(user device environment, network environment) of the present contents industry. And users have difficulties in searching and finding contents since they are served contents they want and contents suitable to diverse context and affection. Therefore, it is necessary to make a system offering contents according to context and affection of users. The study proposes the system to offer contents suitable to context and affection of users whenever and wherever through diverse devices in a ubiquitous environment and designs/implementation a user device framework system that users can be offered contents suitable to their devices.

• KIPS Transactions on Computer and Communication Systems
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• v.2 no.3
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• pp.117-124
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• 2013

In this paper we propose a TFRC(TCP Friendly Rate Control) which guarantees a minimum rate in order to improve the efficiency of the previous TFRC which cannot distinguish congestion losses and wireless losses and decreases throughput both in wired and wireless networks. This TFRC technique is able to guarantee a minimum rate for video by restricting a loss event rate with packet loss probability about existing TFRC and constraining a rate reduction from the feedback timeout. When we experimented both the existing TFRC and the new one with TCP in the same network, we found that the latter is better than the former. Consequently, it shows that the proposed TFRC can improve video streaming quality using a guaranteed minimum transmission rate.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.04b
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• pp.1483-1486
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• 2002

Multicast protocols are efficient methods of group communication, but they do not support the various transmission protocol services like a reliability guarantee, FTP, or Telnet that TCPs do. The purpose of this dissertation is to find a method to utilize sewer routers to form multicasts that can simultaneously transport multicast packets and TCP packets. For multicast network scalability and error recovery the existing SRM method has been used. Three packets per TCP transmission control window size are used for transport and an ACK is used for flow control. A CBR and a SRM is used for UDP traffic control. Divided on whether a UDP multicast packet and TCP unicast packet is used simultaneously or only a UDP multicast packet transport is used, the multicast receiver with the longest delay is measured on the number of packets and its data receiving rate. It can be seen that the UDP packet and the TCP's IP packet can be simultaneously used in a server router.