• Bulletin of the Korean Mathematical Society
• /
• v.33 no.3
• /
• pp.385-392
• /
• 1996

Smale [16] posed the following question; is having an attracting periodic orbit a generic property for diffeomorphisms of two-sphere $S^2\ulcorner$(A generic property of $f \in Diff(M)$ is one that is true for a Baire set in Diff(M)). Mane[5] and Plykin[13] had an positive answer for Axiom A diffeomorphisms of $S^2$. To explain our theorem, we begin by briefly recalling stability conjecture posed by palis and smale.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2008.06a
• /
• pp.851-852
• /
• 2008

• Proceedings of the Korean Institute of Communication Sciences Conference
• /
• 2004.11a
• /
• pp.12-12
• /
• 2004

• Proceedings of the Korean Information Science Society Conference
• /
• 2003.04d
• /
• pp.638-640
• /
• 2003

급변하는 네트워크 서비스에 대한 요구에 신속히 대응하고 새로운 특징에 대한 시스템의 수정과 보완이 용이하도록 고안된 것이 네트워크 프로세서이다. 본 논문은 네트워크 관련 응용에 특화된 인텔의 IXP1200 네트워크 프로세서를 이용하여 Differentiated Service를 위한 간단한 DiffServ Ingress Boundary Node로서의 Edge Router를 설계한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.2B
• /
• pp.105-116
• /
• 2003

The differentiated service architecture is based on a simple model by applying a per-class service in the core node of the network. However, due to the simplified network behavior, the network structure and provisioning were more complicated. If a service provider wants the dynamic provisioning or better bandwidth guarantee, signaling protocol with QoS parameters or admission control method should be deployed in DiffServ network. However, these methods increase the complexity. Therefore, we proposed DPM2 mechanism for admission control in the DiffServ network. In this paper, we describe and survey the admission control methods that are applicable to IP networks and propose also the dynamic provisioning mechanism based on the bandwidth broker and distributed measurement based admission control and movable boundary bandwidth management to support heterogeneous QoS services in differentiated service networks. For the performance evaluation for proposed mechanism, we used ns-2 simulator.

• Journal of KIISE:Computer Systems and Theory
• /
• v.28 no.10
• /
• pp.513-519
• /
• 2001

Home-based Lazy Release Consistency (HLRC) shows poor performance on lock based applications because of two reasons:(1) a whole page is fetched on a page fault while actual modification is much smaller , and(2) the home is at the fixed location while access pattern is migratory, In this paper we present an efficient lock protocol for HLRC. In this protocol, the pages that are expected to be used by acquirer selectively updated using diffs. The diff accumulation problem is minimized by limiting the size of diffs to be sent for each page. Our protocol reduces the number or page faults inside critical sections because pages can be updated by applying locally stored diffs . This reduction yields the reduction of average lock waiting time and the reduction of message amount. The experiment with five applications shows that our protocol archives 2%~40% speedup against base HLRC for four applications.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.12
• /
• pp.46-58
• /
• 2003

The recent Internet is changing from its best-effort service and needs the network structure and traffic engineering, which can support various applications requiring differentiated traffic processing and high quality of service. The extension of the Internet from wired to wireless system generating location-dependent and burst errors make more difficult to support a good service with the existing packet scheduling algorithm. In this paper, we propose a wireless diffserv packet scheduling (WDSPS) algorithm that can provide reliable service in the differentiated wireless internet service network. The proposed scheduling algorithm solves the HOL(head of line) blocking problems of class queue occurred in wireless network, supports the differentiated service for each class which is defined in differentiated service networks and makes possible the gradual and efficient service compensation not only among classes but also among flows to prevent the monopoly of one class or one flow. Through simulations, we show that our proposed WDSPS scheduling algorithm can provide the required QoS differentiation between classes and enhance the service throughput in various wireless network conditions.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.40 no.12
• /
• pp.125-135
• /
• 2003

In this paper, we developmed and implemented router and bandwidth broker that provides end-to-end QoS in differentiated service IP networks. Our design goal is to provide end-to-end premium service using the EF PHB. The bandwidth broker and router were implemented in the FreeBSD 4.6 platform. For the DiffServ router, we implemented QoS daemon, rollback managment routine, monitoring, and COPS-PR client. Also, Ive implemented bandwith broker which has SLS and resource management function, and signaling protocols for interfacing intra-and inter-domain. On the testbed, we have validated and evaluated the performance of the implemented DiffServ router and bandwidth broker using the inter-domain signaling protocol client in MS Windows platform. The test results show that the end-to-end QoS can be guaranteed for the inter-domain diffServ by the implemented system.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.5 no.5
• /
• pp.941-950
• /
• 2001

In this paper, we present the integrated network architecture for supporting mobile IP in third generation mobile communication networks, and propose the end-to-end QoS control mechanisms of DiffServ and QoS control functions of each network element in the proposed network. First, the QoS supporting schemes of IMT-2000 are described. Second, the necessities of integrating the networks are discussed and the integrated architecture are proposed. Third, the mapping between wireless channels and DiffServ classes are presented. Finally, the end-to-end QoS control mechanisms are proposed. We also analyze the link level protocols with QoS provisioning for mobile multimedia assuming that the system support voice and data traffic simultaneously. In case of data traffic, the delay and throughput of SREJ ARQ and Type-1 Hybrid ARQ scheme are compared, and In case of voice traffic, the packet loss rate of BCH coding is analyzed according to the varying data traffic loads. The results indicate that the adaptive link level protocols are efficient to meet the QoS requirements while the complexities are increased.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.11C
• /
• pp.10-23
• /
• 2001

It is difficult to satisfy the QoS(Quality of Service) guarantee which is required by real-time application services only with the Best-Effort(BE) service adopted in the current Internet. Therefore, worldwide research is being made on the method of QoS provisioning. Among them, the QoS guarantee mechanism using the Diffserv(Differentiated Service) was discussed in this paper. First we analyzed how the DiffServ performance was affected by traffic models. For this, we performed the research for the random, bursts, and self-similar traffic modeling method. We then designed and implemented an OPNET simulator, and performed the simulation 7d performance evaluation for diverse input parameters. Based on the results of performance evaluation, it was confirmed that QoS guarantee is possible for the EF(Expedited Forwarding) class with the DiffServ function under every environments considered and the service separation between EF and BE(Best Effort) classes is also possible. We also analyzed the performance variation and dynamic behavior of DiffServ mechanism based on the resource allocation between E? and BE classes in WFQ(Weighted Fair Queueing).