• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.3
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• pp.309-316
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• 2016

Recently, the voice service over a mobile communication system tends to be provided based on the packet-based technology. Even though the sufficient transmission rate is supported by LTE mobile communication system, the quality of VoIP service that is experienced by the user can be degraded by the change in the transmission conditions and the terminal mobility. This paper has established an environment on which experiments are conducted for the different values of the major parameters that represent the transmission conditions. The result can contribute to the decision of the requirement that the mobile system should meet for maintaining the quality of VoIP service.

• The KIPS Transactions:PartA
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• v.16A no.3
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• pp.181-188
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• 2009

Transcoding is one of core techniques that implement VoD services according to QoS. But it consumes a lot of CPU resource. A transcoding proxy transcodes multimedia objects to meet requirements of various mobile devices and caches them to reuse later. In this paper, we propose a service policy that reduces the load of transcoding multimedia objects by degrading QoS in a transcoding proxy. Due to the tradeoff between QoS and the load of a proxy system, a transcoding proxy provides lower QoS than a client's requirement so that it can accomodate more clients.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9A
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• pp.1067-1074
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• 2004

In the wireless mobile networks, it IS important to provide the quality-of-service (QoS) guarantees as they are increasingly expected to support the multimedia applications Although the QoS provisioning problem arises in the wire-line networks as well, the mobility of hosts and the scarcity of bandwidth make QoS provisioning a challenging task in wireless mobile networks. The resource allocation to multimedia applications of varying QoS reqUlrement 15 a complex issue. In this paper, we propose a new adaptive resource allocation scheme based on the concept of the resource reservation and the renegotiation in order to guarantee the QoS of the real-tune traffic. The proposed scheme is aimed at improving the perfonnance in terms of the new call blocking rate, the bandoff dropping rate, and the bandwIdth utilization.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.367-370
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• 2011

Tactical communication environment evolving for the purpose of providing services such as voice, video and text based on ALL-IP. Therefore, To be able to guarantee QoS level which meets the required level of subscriber for these services in the constrained tactical communication infrastructure, it is required to take the characteristics such as wireless transmission link, mobility of troops or personal into service quality scheme. In this paper, to support differentiated QoS for each individual or mission in the tactical communication environment, we presents a technique that can provide same QoS level which was served originally regardless of the situation to user's move through dynamically determining the QoS level to be provided at the time of the service request on VoIP-Switch.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.41-44
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• 2000

Because of internet's growth, today's network has a serious bandwidth problem. WDM(Wavelength Division Multiplexing) is a solution of this problem. In the WDM networks, QoS(Quality of Service) is as important as bandwidth. And today's voice over IP technology makes a lot of delay-sensitive internet traffic. De]ay-sensitive internet traffic is growing up, so more QoS is needed. We proposed effective solution to assign QoS.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.1B
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• pp.7-16
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• 2005

Resource Reservation Protocol(RSVP) can provide Quality-of-Service(QoS) guarantees for real-time services in wired networks. However, RSVP suffers from mobility problem in the mobile Internet. Therefore, to provide seamless QoS services, it is needed that a mobile node makes a reservation everywhere it visits. Recently, many protocols have been proposed to provide QoS guarantees through advance resource reservation. But, these proposals have problems with a waste of bandwidth and the signaling overhead due to advance resource reservation. In this paper, we propose new advance resevation protocol, Proportional Aggregate RSVP(PA-RSVP) to minimize the resource reservation bandwidth and the signaling overhead in the mobile Intemet while providing QoS guarantees. Based on the performance evaluation, we show that the proposed protocol provides an improved performance over existing protocols under various system conditions.

• Journal of Korea Multimedia Society
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• v.7 no.2
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• pp.187-193
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• 2004

Wireless networks play a very important role in communications today. For example, wireless networks today provide from the basic services like e-mail and FTP to the multimedia applications like Web service. It is obvious that QoS requirements to these diverse applications over wireless networks will continue as in wired networks. Much research has been done to develop QoS supporting algorithms on Internet. But due to the limited bandwidth and varying channel states of the wireless networks, it is difficult to support differentiated service over wireless networks. In this paper we propose the modified wireless token ring protocol supporting QoS to the real-time traffic service node over Internet environments in which non-real-time and real-time traffic service nodes coexist. In the proposed algorithm, the real-time traffic service node gets the priority to take token over the non-real-time traffic service node. So the proposed algorithm support quick transmission of the real-time traffic service node. And this advantage can be obtained with minor modification of the legacy wireless token ing protocol to support QoS. We also consider the lost token recovery mechanism.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.1
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• pp.1-13
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• 2001

In this paper, we propose a new dynamic bandwidth allocation and call admission control for VBR video sources with QoS constraints to support an efficient resource management and at the same Lime to satisfy the user's quality or service requirements. For the dynamic bandwidth allocation, first the next amount of traffic is predicted using a modified adaptive linear prediction method that considers abrupt scene change effects. And then, we dynamically allocate the necessary bandwidth to each connection based on the currently provided quality degree by the network with respect to the user's QoS requirements in terms of average delay and loss ratio. For the admission control, we determine the acceptance or rejection or a new connection based on the quality satisfaction degrees of the existing connections. Simulation results show that our proposed dynamic schemes are able to provide a stable service, which well meets the user's quality requirements.

• Journal of Information Technology Applications and Management
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• v.12 no.3
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• pp.129-150
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• 2005

Due to the advance of the Internet, the electronic commerce is getting more widely used, and customer's demand for the e-Commerce service quality is rapidly increasing. On the other hand, e-Commerce companies required the Internet services whose quality is provided more reliable service to their customers. Therefore, it is very important to provide both e-Commerce companies and customers with the measurement and service quality in real-life network environment. But the research on the service quality measurement method for electronic commerce systems has been limited because ISP and e-Commerce providers seldom disclose detailed service measures such as, where and how much service delay incurred. In this paper, we construct sample e-Commerce systems and try to measure the service quality of the systems in real network environment. We have analyzed the delay zones and causes using a measurement tool. We must reflect the improvement method against delay causes. Accordingly, the customers can be experiences the better service quality. We hope that this research will be the groundwork for future research on the service quality of various types of e-Commerce systems and online services.

• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.100-102
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• 2003

최근 인터넷 사용의 폭발적인 증가와 업무에 있어서 네트웍 의존도가 증가함에 따라 최종 사용자들은 좀 더 신뢰성 있는 네트웍 서비스를 요구하게 되었다. 또한 보편적인 인터넷망은 최선형 서비스 (best­effort service)를 모델로 하기 때문에 종단간(end­to­end) QoS(Quality of Service)를 만족시키지 못하고 있다. 따라서, 네트웍 관리자는 최종 사용자 관점에서 네트웍 성능을 모니터링하여 언제, 어느 구간에서 QoS를 만족시키지 못하는지 파악하기를 원한다. 본 논문에서는 IP 상에서의 전송프로토콜 별 종단간 QoS 측정 방법을 연구하고 네트웍 제공자와 사용자간에 체결한 SLA(Service Level Agreement)를 만족하는지 분석하여 문제 구간 및 노드를 파악할 수 있는 시스템의 구조를 제시한다.