• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.12
• /
• pp.59-70
• /
• 2003

Proposed CCRSVP (Candidate Casting RSVP) algorithm is a new fast handoff method which uses advanced multicasting method and RSVP for IEEE 802.11 Wireless LAN (WLAN) environments. The proposed algorithm shows good performance in the handoff latency and the B/W efficiency aspect and guarantees QoS because it uses L2 information (BSSID) of WLAN and starts to reserve resources and multicast packets before L2 handoff completes. We also propose a Markov chain performance analysis model in which we can analyze the handoff performance of various handoff algorithms. Using the model, we compare bandwidth efficiency of the proposed algorithm with existing handoff algorithms which use RSVP by analyzing blocking probability of session, resource usage, and the average number of ongoing session in a cell. The results show that the proposed algorithm shows better performance than the existing algorithms in the above three performance aspects.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.1B
• /
• pp.34-44
• /
• 2003

As the recent rapid development of internet technology and the wide spread of multimedia communications, massive increase of network traffic causes some problems such as the lack of network paths and the bad quality of service To resolve these problems, this paper presents a web-based traffic control system which supports QoS of realtime packet transmission for the multimedia communication The traffic control system presented in this paper applies the integrated service model and provides QoS of packet transmission by means of determining the packet transmission rate according to the policies of network manager and the optimal resource allocation considering the end-to-end traffic load It also provides QoS for the realtime packet transmission through the admission controller and the packet scheduler by the modified $WF^2Q^+$ algorithm support asynchronous and class-based queuing.

• The Transactions of the Korea Information Processing Society
• /
• v.7 no.12
• /
• pp.3785-3793
• /
• 2000

Effective synchronization specification model which can specify temrxlral relationship among media resolving asynchronous problem due to variable network delay is necessary in a distributed multimedia system. Therefore in this paper, we propose RTPN(Real- Time Petri Net) synchronization specification model based on Petri Net for multimedia application in a distributed real time environment. The proposed RTPN model supplies a tlexible decsription of the temporal relationship among various media objects by defining primary key media and relative key media according to delay and importance among media. Firing rule is instantly executed by firing function based on QoS values which supports intra-media and inter-media syncbronization. And asynchronous control algorithm for resynchronization of presentation level is possible more effective supporting of QoS.

• Proceedings of the Korean Information Science Society Conference
• /
• 1998.10a
• /
• pp.302-304
• /
• 1998

본 논문에서는 멀티 캐스트 통신환경을 이용하는 많은 응용들의 다양한 요구들을효율적으로 관리하기 위한 통합관리 모델 IPME를 제안한다. 이를 위해서 멀티캐스트 통신환경에서 발생할 수 있는 제어 및 관리 에 대한 문제들을 분석한다. 또한 제안된 IPME구조를 기본을 멀티캐스트 통신환경을 이용하는 다자간 응영들에서 매우 중요하고 복잡한 문제인 참여 송수신자들의 서로 다른 QoS요구들이 효율적으로 관리될 수 있도록 하는 모델로 구체화된다. 다음으로, 본 논문은 제안된 QoS관리 모델의 타당성을 검증하기 위해서 멀티캐？ 통신환경을 이용하는 대표적인 디자인 응용인 원격화상회의 시스템에 적용한다.

• Journal of Information Processing Systems
• /
• v.18 no.6
• /
• pp.729-740
• /
• 2022

Netflix, Amazon Prime, and YouTube are the most popular and fastest-growing streaming services globally. It is a matter of great interest for the streaming service providers to preview their service infrastructure and streaming strategy in order to provide new streaming services. Hence, the first part of the paper presents a detailed survey of the Content Distribution Network (CDN) and cloud infrastructure of these service providers. To understand the streaming strategy of these service providers, the second part of the paper deduces a common quality-of-service (QoS) model based on rebuffering time, bitrate, progressive download ratio, and standard deviation of the On-Off cycle. This model is then used to analyze and compare the streaming behaviors of these services. This study concluded that the streaming behaviors of all these services are similar as they all use Dynamic Adaptive Streaming over HTTP (DASH) on top of TCP. However, the amount of data that they download in the buffering state and steady-state vary, resulting in different progressive download ratios, rebuffering levels, and bitrates. The characteristics of their On-Off cycle are also different resulting in different QoS. Hence a thorough adaptive bit rate (ABR) analysis is presented in this paper. The streaming behaviors of these services are tested on different access network bandwidths, ranging from 75 kbps to 30 Mbps. The survey results indicate that Netflix QoS and streaming behavior are significantly consistent followed by Amazon Prime and YouTube. Our approach can be used to compare and contrast the streaming services' strategies and finetune their ABR and flow control mechanisms.

• Korean Journal of Anesthesiology
• /
• v.71 no.6
• /
• pp.467-475
• /
• 2018

Background: The Quality of Recovery-40 (QoR-40) is a widely-used, self-rated, and self-completed questionnaire for postoperative patients. The questionnaire is intended to elicit information from each patient regarding the quality of recovery during the postoperative period. It is noteworthy, however, that an official Korean version of the QoR-40 (QoR-40K) has not been established. The purpose of this study was to develop the QoR-40K by translation and cultural adaptation process and to evaluate the validity and reliability of the QoR-40K. Methods: After pre-authorization from the original author of the QoR-40, the translation procedure was established and carried out based upon Beaton's recommendation to create a QoR-40K model comparable to the original English QoR-40. Two hundred surgical patients were enrolled, and each completed the questionnaire during the preoperative period, on the third day, and 1 month after surgery. The QoR-40K was compared with the visual analogue scale (VAS) and another health-related questionnaire, the Short-form Health Survery-36 (SF-36). The method of validation for QoR-40K included test-retest reliability, internal consistency, and level of responsiveness. Results: Spearman's correlation coefficient for test-retest reliability was 0.895 (P < 0.001), and Cronbach's alpha of the global QoR-40K on the third day after surgery was 0.956. A positive correlation was obtained between the QoR-40K and the mental component summary of SF-36 (${\rho}=0.474$, P < 0.001), and a negative correlation was observed between QoR-40K and VAS (${\rho}=-0.341$, P < 0.001). The standardized responsive mean of the total QoR-40K was 0.71. Conclusions: The QoR-40K was found to be as acceptable and reliable as the original English QoR-40 for Korean patients after surgery, despite the apparent differences in the respective patients' cultural backgrounds.

• Journal of the Korean Institute of Telematics and Electronics S
• /
• v.36S no.8
• /
• pp.30-38
• /
• 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 $CLR{\le}2{\times}10^6$ & $GIQ_{mean}{\ge}99.705%$.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
• /
• v.2 no.3
• /
• pp.72-82
• /
• 2003

인터넷의 사용이 폭발적으로 증가함으로 인해 다양한 서비스들의 욕구가 있고 그 중에서도 VoIP가 대표적인 예이다. ITU-T의 Study Group12에서 QoS (Quality of Service)에 관한 연구를 진행하고 있다. 그 중에서도 품질평가 방법에서 전송계획을 위한 G,107의 E-model을 PSTN에서 IP네트워크로 적용하는 연구를 진행하고 있다. VoIP의 QoS문제점을 분석하고 E-model에서 개선되어야 할 파라미터들을 확인하고, 이를 위한 ITU-T의 개선동향을 살펴봄으로써 앞으로의 E-model이 나아가야 할 방향에 대해서 기술하였다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.31 no.5C
• /
• pp.562-567
• /
• 2006

This paper extends Diameter AAA Protocol to provide secure communication channels between Mobile RFID Service Components and distinct service based on user's QoS level authorization. This paper supposes 900MHz, which is the target RF for Mobile RFID Forum and supposes RFID phone, which equitted with RFID reader. By using extended Diameter AAA server, user is authenticated, authorized and provided dynamic security associations between Mobile RFID Service components. The types of security associations are as followings:between RFID tag and RFID reader, between RFID reader(phone) and MobileRFID Service Agent, between phone and OIS, between phone and OTS and between phone and Accounting/Financial server.

• Convergence Security Journal
• /
• v.14 no.7
• /
• pp.45-51
• /
• 2014

The most important point in the QoS management system to ensure the quality of the IoT system design goal is quality measurement system and the quality evaluation system. This research study is a matrix model for the IoT based on key quality measures by diagnosis system structure and function. Developing for the quality metrics measured Internet of Things environment will provide the foundation for the Internet of Things quality measurement/analysis. IoT matrix system for quality evaluation is a method to describe the functional requirements and the quality requirements in a single unified table for quality estimation performed. Comprehensive functional requirements and quality requirements by assessing the association can improve the reliability and usability evaluation. When applying the proposed method IoT quality can be improved while reducing the QoS signaling, the processing, the basis for more efficient quality assurances as a whole.