• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권2호
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• pp.522-541
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• 2016

Network virtualization provides an effective way to overcome the Internet ossification problem. As one of the main challenges in network virtualization, virtual network embedding refers to mapping multiple virtual networks onto a shared substrate network. However, existing heuristic embedding algorithms evaluate the embedding potential of the nodes simply by the product of different resource attributes, which would result in an unbalanced embedding. Furthermore, ignoring the hops of substrate paths that the virtual links would be mapped onto may restrict the ability of the substrate network to accept additional virtual network requests, and lead to low utilization rate of resource. In this paper, we introduce and extend five node attributes that quantify the embedding potential of the nodes from both the local and global views, and adopt the technique for order preference by similarity ideal solution (TOPSIS) to rank the nodes, aiming at balancing different node attributes to increase the utilization rate of resource. Moreover, we propose a novel two-stage virtual network embedding algorithm, which maps the virtual nodes onto the substrate nodes according to the node ranks, and adopts a shortest path-based algorithm to map the virtual links. Simulation results show that the new algorithm significantly increases the long-term average revenue, the long-term revenue to cost ratio and the acceptance ratio.

• 디지털융복합연구
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• 제14권10호
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• pp.303-310
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• 2016

인터넷의 경직성으로 인하여 다양한 서비스를 제공하기 어려운 문제를 해결하기 위한 가장 효과적인 방법이 네트워크 가상화 방안이다. 공통의 물리 네트워크 자원을 공유하는 가상 네트워크를 효율적으로 생성하기 위해서는 자원을 효율적으로 사용할 수 있는 방안이 필요하다. 이러한 한정된 물리 자원을 효율적으로 사용하기 위하여 본 논문에서는 사용중인 자원이라도 더 높은 서비스 우선순위를 갖는 가상 네트워크에 할당하는 방법을 제안한다. 높은 우선순위의 네트워크 생성 요청을 위하여 운용중인 낮은 우선순위의 가상 네트워크에서 효율적으로 대역폭을 회수하는 알고리즘을 제안한다. 제안하는 대역폭 할당 알고리즘은 낮은 우선순위를 갖는 가상 네트워크에서 서비스 지속성을 유지하면서 할당된 대역폭을 회수할 수 있다. 제안한 알고리즘의 실험을 통하여 약 8%정도의 가상 네트워크 생성 수락률의 향상을 확인하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권8호
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• pp.3841-3861
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• 2017

Virtualized small cell network is a promising architecture which can realize efficient utilization of the network resource. However, conventional full duplex self-backhauls lead to residual self-interference, which limits the network performance. To handle this issue, this paper proposes a virtual resource allocation, in which the residual self-interference is fully exploited by employing a physical-layer network coding (PNC) aided self-backhaul scheme. We formulate the features of PNC as time slot and information rate constraints, and based on that, the virtual resource allocation is formulated as a mixed combinatorial optimization problem. To solve the problem efficiently, it is decomposed into two sub problems, and a two-phase iteration algorithm is developed accordingly. In the algorithm, the first sub problem is approximated and transferred into a convex problem by utilizing the upper bound of the PNC rate constraint. On the basis of that, the convexity of the second sub problem is also proved. Simulation results show the advantages of the proposed scheme over conventional solution in both the profits of self-backhauls and utility of the network resource.

• 한국CDE학회논문집
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• 제15권5호
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• pp.343-353
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• 2010

Time to market and cost-efficient production are some of the challenge that manufacturing industries face. Modern methods of engineering can't help such organizations attain competitive advantage. To help these situations, MEMPHIS (Middleware for Exchanging Machinery and Product Data in Highly Immersive Systems) was introduced as an approach that enables VE (Virtual Engineering) and links engineering applications with VR (Virtual Reality) solutions. Thus an environment is provided to implement virtual design reviews and enable the application of virtual prototyping methods. However MEMPHIS could just handle Product data for virtual design review and simulation. In this paper, we newly define and develop the extended MEMPHIS that enables virtual manufacturing with Process, Resource and Plant data as well as Product data.

• 한국전자통신학회논문지
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• 제5권4호
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• pp.406-411
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• 2010

지난 수년간 Honeynet은 공격자의 공격 도구, 공격 기법 및 공격동기를 배울 수 있는 보안 메커니즘으로서의 가치가 충분히 입증되었다. 이러한 정보는 다양한 위협에 대한 조직의 대응을 위한 핵심 정보로 활용되어 보다 효율적인 보안을 위한 기초자료가 되고 있다. 그러나 Honeynet활용의 문제점 중 하나는 구축에 많은 자원이 요구되며, 구축 및 운영관리가 어렵다는 문제이다. Honeynet 구축을 위해서는 다수의 시스템들과 다양한 보안 메커니즘을 필요로 한다. 본 논문에서는 최근 IT분야의 화두로 떠오르고 있는 가상화(Virtualization) 기술을 이용하여 기존의 Honeynet의 가치를 그대로 유지하면서도 기존 Honeynet의 자원문제, 구축 및 운영관리문제를 줄일 수 있는 Virtual Honeynet 모델을 제시하고자 한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권12호
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• pp.4776-4798
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• 2015

The location selection of virtual machines in distributed cloud is difficult because of the physical resource distribution, allocation of multi-dimensional resources, and resource unit cost. In this study, we propose a multi-object virtual machine location selection algorithm (MOVMLSA) based on group information, doubly linked list structure and genetic algorithm. On the basis of the collaboration of multi-dimensional resources, a fitness function is designed using fuzzy logic control parameters, which can be used to optimize search space solutions. In the location selection process, an orderly information code based on group and resource information can be generated by adopting the memory mechanism of biological immune systems. This approach, along with the dominant elite strategy, enables the updating of the population. The tournament selection method is used to optimize the operator mechanisms of the single-point crossover and X-point mutation during the population selection. Such a method can be used to obtain an optimal solution for the rapid location selection of virtual machines. Experimental results show that the proposed algorithm is effective in reducing the number of used physical machines and in improving the resource utilization of physical machines. The algorithm improves the utilization degree of multi-dimensional resource synergy and reduces the comprehensive unit cost of resources.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권9호
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• pp.4023-4043
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• 2016

Network virtualization has been regarded as a core attribute of the Future Internet. In a network virtualization environment (NVE), multiple heterogeneous virtual networks can coexist on a shared substrate network. Thus, a substrate network failure may affect multiple virtual networks. In this case, it is increasingly critical to provide survivability for the virtual networks against the substrate network failures. Previous research focused on mechanisms that ensure the resilience of the virtual network. However, the resource efficiency is still important to make the mapping scheme practical. In this paper, we study the survivable virtual network embedding mechanisms against substrate link and node failure from the perspective of improving the resource efficiency. For substrate link survivability, we propose a load-balancing and re-configuration strategy to improve the acceptance ratio and bandwidth utilization ratio. For substrate node survivability, we develop a minimum cost heuristic based on a divided network model and a backup resource cost model, which can both satisfy the location constraints of virtual node and increase the sharing degree of the backup resources. Simulations are conducted to evaluate the performance of the solutions. The proposed load balancing and re-configuration strategy for substrate link survivability outperforms other approaches in terms of acceptance ratio and bandwidth utilization ratio. And the proposed minimum cost heuristic for substrate node survivability gets a good performance in term of acceptance ratio.

• ETRI Journal
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• 제36권2호
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• pp.197-205
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• 2014

This paper proposes a novel framework for virtual content delivery networks (CDNs) based on cloud computing. The proposed framework aims to provide multimedia content delivery services customized for content providers by sharing virtual machines (VMs) in the Infrastructure-as-a-Service cloud, while fulfilling the service level agreement. Furthermore, it supports elastic virtual CDN services, which enables the capabilities of VMs to be scaled to encompass the dynamically changing resource demand of the aggregated virtual CDN services. For this, we provide the system architecture and relevant operations for the virtual CDNs and evaluate the performance based on a simulation.

• 한국멀티미디어학회논문지
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• 제4권2호
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• pp.130-135
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• 2001

네트워크를 이용한 가상현실시스템이 3차원 그래픽 뿐만 아니라 오디오, 비디오를 취급하면, 가상 공간의 품질은 현재 사용 가능한 네트워크 대역폭이나 엔드 시스템의 자원에 커다란 영향을 받는다. 또한 자원 예약형의 네트워크를 사용하더라도 네트워크형 가상현실 시스템에서는 사용자의 공간 네비게이션에 따라 요구되는 자원이 변화하므로 결국 가상공간의 품질이 떨어지는 결과를 초래한다 본 논문에서는 네트워크형 가상현실 시스템에서의 자원 할당 방법을 제안하여 네비게이션에 따른 가상공간의 품질 저하를 최소화하며 이를 실험을 통해 그 효율성을 입증한다.

• 한국컴퓨터정보학회논문지
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• 제18권2호
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• pp.41-47
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• 2013

본 논문에서는 개방 시스템 기반 가상 자원 모니터링 시스템을 CPU, 메모리, 디스크, 네트워크 부분으로 세분화 하고 각각 모듈화하여 설계 및 구현하였다. 설계한 시스템을 구현하기 위해 Windows, Linux, Xen 운영체제를 이용하였고, 구현 언어로는 C++를 사용하였다. 그리고 시스템의 구조는 기능 업그레이드 및 추가 등의 확장성을 고려하여 가능한 기능별로 모듈화 하여 클라우드 컴퓨팅 환경에서 적용 가능한 클라우드 컴퓨팅 가상 자원 모니터링 시스템을 구현하였다. 본 논문에서 설계 및 구현한 클라우드 컴퓨팅 가상 자원 모니터링 시스템의 동작성 검사를 위해 테스트베드를 구축하여 Xen, ESX 하이퍼바이저 운영체제에서 테스트 한 결과 실시간으로 CPU, 메모리, 디스크, 네트워크 정보를 정상적으로 모니터링 함을 확인 하였다.