• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.8
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• pp.30-38
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• 1999

On providing MPEG-2 video service through the ATM network, it is necessary for network provider to have the ATM QoS objectives in order to guarantee quality of service required by end users at the application layer. In this paper, the degradation of QoS caused by cell losses at application layer is assessed quantitatively by GIQ model considering AAL layer and is evaluated qualitatively by MOS from the viewpoint of the end users in order to analyze the relation between CLR and QoS of MPEG-2 video. From the simulation and empirical results, we know that CLR and $GIQ_{mean}$ for guaranteeing QoS of MOS grade 5(Excellent) are $CLR{\le}4{\times}10^7$ & $GIQ_{mean}{\ge}99.4%$ and those for guaranteeing QoS of MOS grade 4(Good) are $CLR{\le}2{\times}10^6$ & $GIQ_{mean}{\ge}99.705%$.

• Quality Improvement in Health Care
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• v.15 no.1
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• pp.79-87
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• 2009

문제: 본원의 외래 상황은 진료의가 짧은 시간 내에 많은 환자를 진료해야 하고, 진료 환자 모두에게 충분히 만족하도록 설명해주는 것은 매우 어려운 실정이었다. 2007년의 의료기관 본 평가에 앞서 병원 자체 평가 결과 외래환자의 설명 만족도는 57점으로 저조하였다. 목적: "이해하기 쉽게 설명하는 서울대학교 병원" 이라는 슬로건 하에 설명간호사 제도를 운영하기 시작하여, 설명간호사실 운영 활성화를 통한 외래 환자 만족도를 향상시키고자 한다. 의료기관: 서울시 종로구에 소재한 대학병원 질 향상 활동: 설명간호사실 방문율 증가 및 one-stop service care을 실현할 수 있는 방안을 모색하였고, 검사 시행 이유, 귀가 후 주의사항 검사 결과, 검사일정 외래 진료 안내 브로셔 및 표준화된 교육 자료를 개발하였다. 또한 설명간호사의 역할 및 업무의 확립을 위한 업무기술서를 개발 및 설명간호사실 환경을 개선하였다. 개선효과: 설명간호사실의 방문율이 내과는 2배, 신경과는 3배 정도 증가하였다. 표준화된 교육 자료 개발로 설명 요구도를 충족시켰고, '환자의 알 권리'와 '설명을 들을 권리'를 보장하였다. 업무기술서 개발로 설명간호사의 업무 및 역할을 확립하였으며 설명간호사실의 환경 개선으로 개인 신상 비밀을 보호받을 권리를 보장하였다. 외래 설명만족도가 2007년 57점에서 2008년 74점으로 향상되었다. 설명간호사실 자체 설문조사에서도 97%가 만족한다고 답하였고, 100% 모두 재방문 의사를 보였다. one-stop service care를 제공함으로써 외래가 복잡하다는 부정적인 이미지를 긍정적인 이미지로 변화시켰다.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.203-210
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• 2006

Fair packet scheduling algorithms supporting quality-of-services of real-time multimedia applications can be classified into the following two design schemes in terms of the reference time used in calculating the timestamp of arriving packet: Finish-time Design (FD) and Start-time Design (SD) schemes. Since the former can adjust the latency of a flow with raising the flow's reserved rate, it has been applied to a router for the guaranteed service of the IETF (Internet Engineering Task Force) IntServ model. However, the FD scheme may incur severe bandwidth loss for traffic flows requiring low-rate but strong delay bound such as internet phone. In order to verify the usefulness of the SD scheme based router for the IETF guaranteed service, this paper analyzes and compares two design schemes in terms of bandwidth and payload utilizations. It is analytically proved that the SD scheme is better bandwidth utilization than the FD one, and the simulation result shows that the SD scheme gives better payload utilization by up to 20%.

• KIISE Transactions on Computing Practices
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• v.20 no.12
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• pp.688-693
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• 2014

With the advent of ubiquitous environments, the smart phone has come into wide use and the demand for various content increases. Thus, in order to efficiently utilize limited resources cognitive radio technology is regarded as a possible solution. Besides spectrum sensing or access schemes, the provision of VoIP traffic service for secondary users with limited spectrum resources is a very important issue. In this paper, a resource allocation and control system for VoIP QoS provision in cognitive radio networks is proposed. Firstly, as the system model, the time structure of the network is addressed and, according to the structure, a bandwidth broker is proposed. In addition, based on available bandwidth estimated by the bandwidth broker, a connection admission control for secondary users is developed. It is demonstrated that the provision of VoIP QoS is greatly affected by channel utilization, the number of channels, and the length of timeslot.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.6
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• pp.221-235
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• 2010

Internet service providers provide various security services, such as firewall, intrusion detection, intrusion prevention, anti-virus, along with their main Internet services. Those security service users have no idea what kind of quality services they are guaranteed. And therefore, Internet users interest in Security Service Level Agreement(SLA) increases as their interest in secure Internet service increases. However, there wasn't any researches in the S-SLA area domestically and there are only limited SLA indexes related to system or service maintenances at the moment. Therefore, this paper analyses security functions in IPS services and categorize them into common and independent security functions. Finally to improve quality of security services, this paper proposes S-SLA indexes depending on the different security levels. This will be subdivide into agreement on security service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.4B
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• pp.319-328
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• 2009

IEEE 802.16e standard defines different Sleep Mode Operations according to kind of services which aims at saving energy for MS efficiently. The previous study of Sleep Mode Operation is limited for single service environment, real sleep interval is decreased because different Sleep Mode Operations are applied at once when MS is on multi service. The proposed Enhanced Sleep Mode Operation increasing real sleep interval of this paper guarantees QoS(Quality of Services) which is same as standard, minimizes energy consumption when different Sleep Mode Operations are applied at once. Therefore Enhanced Sleep Mode Operation of this paper will be useful in case of increase battery life time as well as guaranteeing QoS for MS in IEEE 802.16 system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.805-810
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• 2005

According to the user requirements for continuous and real-time multimedia information, the concept of Quality of Service (QoS) has emerged as a main issue in mobile ad-hoc networks. QoS routing is to find the route that meets the QoS requirements of the users. In this paper, we propose a routing protocol that is based on AODV over TDMA, one of the typical routing protocols for mobile ad-hoc networks, by making a bandwidth reservation for QoS guarantee. While the existing schemes calculate the maximum available bandwidth for each candidate path, our scheme is to check only if the bandwidth of a given path satisfies the end-to-end QoS requirement and then to make a reservation by allocating time slots efficiently in the wireless environment. In order to evaluate the performance of the proposed QoS routing protocol, some simulations are carried out in the ad-hoc environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3B
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• pp.144-151
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• 2008

In this paper, we propose a video streaming server that guarantees a certain level of quality when a server should serve video streaming service to multiple heterogenous clients simultaneously with TCP transport. If each heterogeneous client requests video streaming service in according to its own requirement such as bitrate of content and these requests are accepted by a server, then TCP flows for each video streaming session fairly share limited uplink bandwidth of the server. At this time, because TCP's bandwidth fair-share characteristics can result in bandwidth shrinkage of higher bitrate video streaming session, the client of higher bitrate video may suffer sluggish playback which is related with streaming QoS degradation. To tackle this problem, our proposed server system uses multiple TCP connections adaptively for each video streaming session depending on the anticipated status of the client playout buffer. Simulation results show that our proposed algorithm can successfully reduce the occurrence of playout buffer underrun and enhance streaming quality for whole video clients.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1A
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• pp.19-27
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• 2011

WiBro is a wireless mobile communication system which supports a high data rate and high mobility in anywhere and anytime. Although WiBro system provides multimedia service including data, audio and video services, customers require better service quality in WiBro system. But, many researches have theoretically evaluated the performance of WiBro system without systematic studies by simulation. Therefore, in this paper, we evaluate a performance of WiBro system using OPNET simulator. We analyze system performance according to various modulation and coding schemes, and propose Adaptive Modulation and Coding (AMC) profile to support quality of services for user requirements. Also we evaluate the performance of WiBro system using AMC and Hybrid-Automatic Repeat Request (H-ARQ) technologies, and confirm that the proposed AMC profile can be applied to WiBro system with high performance.

• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.87-92
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• 2008

This paper proposes a session control model for the P2P(Peer to Peer) IPTV(Internet Protocol Television) services and presents the IPTV session control procedures based on the proposed model. Since, while public IPTV traffic is usually processed via a separate network, P2P IPTV traffic is processed together with the conventional Internet access traffic, the P2P IPTV control mechanism needs to provide multi-stream processing for the constituent TPS(Triple Play Service) traffic and corresponding QoS(Quality of Service) control functions. Besides, P2P IPTV session control mechanism should provide appropriate multicast control functions in order to support effective transmission of video traffic generated by personal IPTV broadcasters. The P2P IPTV session control model proposed in this paper is designed to be based on the standard SIP(Session Initiation Protocol), IGMP(Internet Group Management Protocol), and COPS(Common Open Policy Service) protocol so that it can contribute to the easy and prompt deployment of inter-operable P2P IPTV platform.