• 한국통신학회논문지
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• 제25권9B호
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• pp.1542-1550
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• 2000

이동통신망에서 RF 신호를 송수신하는 기지국(base station)과 이동 통신 신호의 교환 전송을 담당하는 중앙국(central station)을 광섬유로 연결하여 구성한 SCM(Subcarrier Multiplexing) 광링크는 RF 신호를 효율적이고 경제적으로 전송하는 시스템으로 널리 사용되고 있다. 그러나 링크의 전송 성능이 광전송 링크와 무선링크의 다양한 환경에 의해 크게 제한되므로, 본 논문에서는 이동통신망에서 CDMA RF 신호전송을 위한 SCM 광링크 시스템의 분석적 모델을 제시하고 다양한 링크 환경에서 전송 성능을 분석하였다. 특히, 광전송 링크에서 레이저 다이오드(LD: Laser Diode)에 의해 발생하는 비선형 왜곡과 무선링크에서 다중 가입자에 의해 발생되는 다중접속간섭(MAI: Multiple Access Interference)을 고려하여 최적의 전송 성능 조건을 제시하였다. 제안된 분석적 모델링으로부터 얻은 성능분석을 통해 최적의 시스템 성능은 사용된 코드의 길이나 다중 가입자의 수에 따라 변화하며 광링크 고유의 잡음과 LD 비선형 왜곡에 의한 영향이 최소가 되는 광변조지수(optical modulation index)를 선택함으로써 얻어짐을 알 수 있었다.

• 디지털산업정보학회논문지
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• 제13권2호
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• pp.13-25
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• 2017

Recently, the high performance of tactical situation display console and tactical data links are used to integrate the operational situations in accordance with information age and NCW (Network Centric Warfare). The tendency to maximize the efficiency of task execution has been developed by sharing information and the state of the battle quickly through complex and diverse information exchange. Tactical data link is a communication system that shares the platform with core components of weapons systems and battlefield situation between the command and control systems to perform a Network Centric Warfare and provides a wide range of tactical data required for decision-making and implementation.It provides the tactical information such as tactical information such as operational information, the identification of the peer, and the target location in real time or near real time in the battlefield situation, and it is operated for the exchange of mass tactical information between the intellectuals by providing common situation recognition and cooperation with joint operations. In this study, still image management, audio file management, tactical screen recording and playback using the storage and playback, NITF (National Imagery Transmission Format) message received from the displayer integrates the tactical situation in three dimensions according to multiple data link operation to suggest ways to ensure data integrity between the data link processor during the entire operation time.

• 융합정보논문지
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• 제9권7호
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• pp.1-7
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• 2019

최근 차세대 무선통신인 5G가 일상 생활에서 실용화되면서 다양한 분야에서 많은 변화가 이루어지고 있다. 그러나, 5G의 향상된 속도와 지연 시간이 개선되었지만 여전히 사용자 보안에 대한 개선이 요구되어 지고 있다. 본 논문에서는 5G의 이질적인 환경에서 사용자의 프라이버시 정보를 효율적으로 보호하기 위한 다중 그룹의 정보 관리 기법을 제안한다. 제안 기법은 서로 다른 이기종의 장치에서 생성되는 사용자의 프라이버시 정보를 서로 다른 그룹에서 연계 처리할 수 있도록 연계 정보를 클러스터링하여 분산 관리할 수 있도록 하는 것이 목적이다. 제안 기법은 주기적으로 사용자의 프라이버시 정보를 동기화하여 사용자별 프라이버시 정보를 가상의 공간에서 독립적으로 처리한다.

• 한국정보과학회논문지:소프트웨어및응용
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• 제26권8호
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• pp.939-954
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• 1999

데이타마이닝 분야에서는 대용량의 트랜잭션 데이타베이스와 같은 하나의 데이타베이스로부터 연관 규칙을 찾는 연구가 많이 수행되어왔다. 그러나, 창고형 할인매장이나 백화점 같이 고객 카드를 이용하는 판매점의 등장으로, 단지 트랜잭션에 대한 분석 뿐만이 아니라, 트랜잭션과 고객과의 관계에 대한 분석 또한 요구되고 있다. 즉, 두 개의 데이타베이스로부터 연관 규칙을 찾는 연구가 필요하다. 이 논문에서는 두 데이타베이스 사이에 링크를 생성하여 연관 항목집합을 찾는 알고리즘을 제안한다. 실험 결과, 링크를 이용한 알고리즘은 고객 데이타베이스가 메모리에 거주가능한 크기라면 시간에 따른 분석에 유용함을 보여주었다.Abstract There have been a lot of researches of mining association rules from one database such as transaction database until now. But as the large discount store using customer card emerges, the analysis is not only required about transactions, but also about the relation between transactions and customer data. That is, it is required to search association rules from two databases. This paper proposes an efficient algorithm constructing links from one database to the other. Our experiments show the algorithm using link is useful for temporal analysis of memory-resident customer database.

• IEIE Transactions on Smart Processing and Computing
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• 제6권1호
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• pp.60-65
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• 2017

Network virtualization enables us to make efficient use of resources in a physical network by embedding multiple virtual networks in the physical network. In this paper, we develop a prototype of a virtual network embedding system. Our system consists of OpenStack, which is an open source cloud service platform, and shell scripts. Because OpenStack does not provide a quality of service control function, we realize bandwidth reservation for virtual links by making use of the ingress policing function of Open vSwitch, which is a virtual switch used in OpenStack. The shell scripts in our system automatically construct the required virtual network on the physical network using the OpenStack command-line interface, and they reserve bandwidth for virtual links using the Open vSwitch command. Experimental evaluation confirms that our system constructs the requested virtual network and appropriately allocates node and link resources to it.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권5호
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• pp.1354-1372
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• 2012

Route establishment in Mobile Ad Hoc Network (MANET) is the key mechanism to a successful connection between a pair of source and destination nodes. An efficient routing protocol constructs routing path with minimal time, less routing overhead and capable of utilizing all possible link connectivity. In general, most on-demand MANET routing protocols operates over symmetrical and bidirectional routing path, which is infeasible due to the inherent heterogeneous properties of wireless devices. Simulation results show that the presence of unidirectional links on a network severely affect the performance of a routing protocol. In this paper, a robust protocol independent scheme is proposed, which enable immediate rediscovery of alternative route for a path blocked by a unidirectional link. The proposed scheme is efficient; route rediscovery is locally computed, which results in significant minimization of multiple route packets flooding. Nodes may exploit route information of immediate neighbors using the local reply broadcast technique, which then redirect the control packets around the unidirectional links, therefore maintaining the end-to-end bidirectional connection. The proposed scheme along with Ad Hoc On-demand Distance Vector (AODV) and AODV-Blacklist routing protocol is investigated over three types of mobility models. Simulation results show that the proposed scheme is extremely reliable under poor network conditions and the route connectivity can be improved by as much as 75%.

• 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.

• 전자공학회논문지B
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• 제28B권10호
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• pp.807-821
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• 1991

A mulitpath MIN(Multistage Interconnection Network), CSMP(Chained Shuffle Multi-Path) network, is proposed, having fault-tolerance and dynamic reroutability. The number of stages and the number of links between adjacent stagges are the same as in single path MINs, so the overall hardware complexity is considerably reduced in comparison with other multipath MINs. The CSMP networks feature links between switches belonging to the same state, forming loops of switches. The network can tolerate multiple faults, up to (N/4)*(log$_2$N-1), having occured in any stages including the first and the last ones(N:NO. of input). To analyze reliability, terminal reliability (TR) and mean time to failure( MTTE) age given for the networks, and the TR figures are compared to those of other static and dynamic rerouting multipath MINs. Also the MTTE figures are compared. The performance of the proposed network with respect to its bandwidth (BW) and probability of acceptance(PA) is analyzed and is compared to that of other more complex multipath MINs. The cost efficiency analysis of reliability and performance shows that the network is more cost-effective than other previously proposed fault-tolerant multipath MINs.

• Journal of Communications and Networks
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• 제9권2호
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• pp.118-127
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• 2007

We propose a link adaptation and selection method for the links constituting an orthogonal frequency division multiplexing (OFDM) based wireless relay network. The proposed link adaptation and selection method selects the forwarding, modulation, and channel coding schemes providing the highest end-to-end throughput and decides whether to use the relay or not. The link adaptation and selection is done for each sub-channel based on instantaneous signal to interference plus noise ratio (SINR) conditions in the source-to-destination, source-to-relay and relay-to-destination links. The considered forwarding schemes are amplify and forward (AF) and simple adaptive decode and forward (DF). Efficient adaptive modulation and coding decision rules are provided for various relaying schemes. The proposed end-to-end link adaptation and selection method ensures that the end-to-end throughput is always larger than or equal to that of transmissions without relay and non-adaptive relayed transmissions. Our evaluations show that over the region where relaying improves the end-to-end throughput, the DF scheme provides significant throughput gain over the AF scheme provided that the error propagation is avoided via error detection techniques. We provide a frame structure to enable the proposed link adaptation and selection method for orthogonal frequency division multiple access (OFDMA)-time division duplex relay networks based on the IEEE 802.16e standard.

• 한국통신학회논문지
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• 제28권12A호
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• pp.945-950
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• 2003

10GbE 스위치간 링크 집합 기술은 프레임 분배 알고리즘의 설계에 따라 스위치에서 성능의 차이를 가져오므로 링크 집합의 장점을 살리려면 좋은 성능을 가지는 프레임 분배 알고리즘이 필요하다. 기존에 제시된 스위치와 스위치 사이에서의 프레임 분배 방식으로 정적 / 동적 프레임 분배 방식이 있으나 이 방식은 수신단말이 여러 개의 물리적인 링크 중 하나의 링크에 고정이 되어 프레임을 전송하기 때문에 집합된 링크를 모두 사용하지 못해 링크 집합의 이점을 충분히 활용하지 못한다. 이 문제점을 해결하기 위해 스위치간 링크 합에 패딩을 이용한 분배 방식의 적용을 제안하고 성능 측면에서 정적 / 동적 분배 방식과 비교하였다. 그 결과 제안된 패딩 방식의 성능이 부하가 0.7이하이고 프레임 평균 길이가 954 바이트보다 더 긴 경우에 더 우수한 성능을 보였다.