• Proceedings of the Korean Information Science Society Conference
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• 2003.10c
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• pp.4-6
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• 2003

IP망을 활용한 VPN(Virtual Private Network)에서의 QoS 보장 메커니즘과 광대역폭 제공에 대한 해결책으로 차세대 광 인터넷을 통한 OVPN(Optical VPN) 기술이 제시되고 있다. 차세대 광 인터넷의 구현이 IP/GMPLS(Generalized Multi­Protocol Label Switching) over DWDM(Dense Wavelength Division Multiplexing) 프로토콜 프레임워크로 표준화되고 있는 현실에 비추어, IP/GMPLS over DWDM 백본망을 통한 OVPN은 차세대 가상사설망으로써 멀티미디어 서비스 제공을 위한 최적의 방안이다. 이러한 차세대 멀티미디어 서비스 제공을 위한 OVPN에서는 서비스 클래스별로 차등화된 광 QoS 제공 및 보장 기술이 절실히 요구되고 있으므로, 본 논문에서는 차등화된 광 QoS 서비스(DOQS:Differetiated Optical QoS Service)를 제공하는 OVPN모델을 제시하고 제안된 DOQS­OVPN 모델의 QoS 지원 광경로상에서의 QoS Failure에 대한 서비스별 차등화된 Recovery 능력을 갖는 QoS 보장 프로토콜 프레임워크를 제안한다.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.655-664
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• 2002

The focus of quality-of-service routing has been on the routing of a single path satisfying specified QoS constraints. However upon failure of a node or link on the path, a new path (backup path) satisfying the constraints has to be established. This paper proposed the fault recovery QoS Rerouting algorithms to recovery the service of applications under fault environment of network. For this, we describes the generation method of PFC (Protection Fundamental Cycle) protecting all of network nodes and suggests path selection algorithms using minimization rerouting cost problem and analyzes the performances of these.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.105-108
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• 2003

In the next generation backbone networks based on dense-wavelength division multiplexing (DWDM), the routing and wavelength assignment with quality-of-service (QoS) recovery is essentially needed to support a wide range of communication-intensive and real-time multimedia services. This paper proposes a new dpmic routing method called as MW-MIPR (MultiWavelength-Minimum Interference Path Routing), which chooses a route that does not interfere too much with many potential future connection requests. This paper also proposes a differentiated RWA mechanisms combined with MW-MIPR algorithm to provide QoS recovery for various multimedia applications in the next generation backbone networks based on DWDM.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.760-773
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• 2003

The Internet is evolving from best-effort service toward an integrated or differentiated service framework with quality-of-service (QoS) assurances that are required for new multimedia service applications. Given this increasing demand for high bandwidth Internet with QoS assurances in the coming years, an IP/MPLS-based control plane combined. with a wavelength-routed dense-wavelength division multiplexing (DWDM) optical network is seen as a very promising approach for the realization of future re-configurable transport networks. This paper proposes a differentiated lambda establishment process for QoS guarantees based on the differentiated MPLS service (DMS) model. According to the QoS characteristics of wavelength in optical links and the type of used Optical Cross-Connect (OXC) nodes in DWDM next generation optical Internet backbone network, a differentiated wavelength assignment strategy that considers QoS recovery capability is also suggested.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4287-4306
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• 2016

Network resilience provides an effective way to overcome the problem of network failure and is crucial to Internet protocol (IP) network management. As one of the main challenges in network resilience, recovering from link failure is important to maintain the constancy of packets being transmitted. However, existing failure recovery approaches do not handle the traffic engineering problem (e.g., tuning the routing-protocol parameters to optimize the rerouting traffic flow), which may cause serious congestions. Moreover, as the lack of QoS (quality of service) restrictions may lead to invalid rerouting traffic, the QoS requirements (e.g., bandwidth and delay) should also be taken into account when recovering the failed links. In this paper, we first develop a probabilistically correlated failure model that can accurately reflect the correlation between link failures, with which we can choose reliable backup paths (BPs). Then we construct a mathematical model for the failure recovery problem, which takes maximum rerouting traffic as the optimizing objective and the QoS requirements as the constraints. Moreover, we propose a heuristic algorithm for link failure recovery, which adopts the improved k shortest path algorithm to splice the single BP and supplies more protection resources for the links with higher priority. We also prove the correctness of the proposed algorithm. Moreover, the time and space complexity are also analyzed. Simulation results under NS2 show that the proposed algorithm improves the link failure recovery rate and increases the QoS satisfaction rate significantly.

• The KIPS Transactions:PartC
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• v.16C no.3
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• pp.363-372
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• 2009

For large scale VOD service, cluster servers are spotlighted to their high performance and low cost. A cluster server usually consists of a front-end node and multiple back-end nodes. Though increasing the number of back-end nodes can result in the more QoS streams for clients, the possibility of failures in back-end nodes is proportionally increased. The failure causes not only the stop of all streaming service but also the loss of the current playing positions. In this paper, when a back-end node becomes a failed state, the recovery mechanisms are studied to support the unceasing streaming service. For the actual VOD service environment, we implement a cluster-based VOD servers composed of general PCs and adopt the parallel processing for MPEG movies. From the implemented VOD server, a video block recovery mechanism is designed on parity algorithms. However, without considering the architecture of cluster-based VOD server, the application of the basic technique causes the performance bottleneck of the internal network for recovery and also results in the inefficiency CPU usage of back-end nodes. To address these problems, we propose a new failure recovery mechanism based on the pipeline computing concept.

• Korean Journal of Anesthesiology
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• v.71 no.6
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• pp.467-475
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• 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 Digital Contents Society
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• v.6 no.1
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• pp.85-88
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• 2005

The requirement of distributed multimedia applications is the need for sophisticated QoS(quality of service) management. In terms of distributed multimedia systems, the most important catagories for quality of service are a timeless, volume, and reliability. In this paper, we discuss a method for increasing reliability through fault tolerance. We describe the desist and implementation of the ERA running on distributed multimedia environment ERA is a system is able to recover automatically a software error based on distributed multimedia. This paper explains a performance analysis of an error recovery system running on distributed multimedia environment using the rule-based DEVS modeling and simulation techniques. In DEVS, a system has a time base, inputs, states, outputs, and functions.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.8
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• pp.318-330
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• 2003

The advantages of "VPN over Internet" are cost-effectiveness and flexibility However, the disadvantages are the lack of sufficient QoS mechanism and transmission capacity for high bandwidth service. Given this increasing demand for high bandwidth Internet and QoS assurances in "PN over Internet", IP/GMPLS based control plane combined with a high bandwidth capacity of DWDM optical network is seen as a very favorable approach for the realization of future "OVPN over IP/GMPLS over DWDM" Within OVPN for providing QoS guaranteed multimedia service over the NGOI(Next Generation Optical Internet) based on the "IP/GMPLS over DWDM" concept, differentiated QoS framework is one of the key issues to implement OVPN over DWDM-based NGOI. Keeping in mind that IETF(Internet Engineering Task Force) and ITU-T(International Telecommunication Union) are standardizing IP/GMPLS over DWDM protocol framework as a solution for the NGOI, in this paper, we suggest Optical-LSP establishment and QoS maintenance scheme based on DOQS(Differentiated Optical QoS Service) classes, which are the key issue of DOQS protocol framework for assuring end-to-end QoS in "OVPN over IP/GMPLS over DWDM".

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9B
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• pp.791-798
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• 2004

In case of failure in the IP network, services should be provided via a backup path which fully meets QoS requirements. In this regard, we in this paper suggest simple-PFC(s-PFC) to restore single link failure, iterative-PFC(i-PFC) for multiple link failures, and fault_node Avoidance-PFC(a-PFC) for failures of nodes such as routers. Taking the minimum cost rerouting problem into account, we compare and analyze performance of those three mechanisms carrying out Direct-destination Rerouting(DR).