• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9B
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• pp.1542-1550
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• 2000

Fiber optic link systems based on SCM scheme are widely used as efficient and economic RF signal links between base station and a central station in mobile communication networks. However, its performance can be seriously limited depending on the operational conditions of not only the optical transmission system but also the wireless link in various environments. In this paper, we propose an analytic model for performance analyses of the SCM fiber optic link for CDMA RF signal transmission in various link environments. We present optimal operational conditions taking account of the nonlinear effects of the optical transmission system, and the multiple access interference produced at the wireless link. It has been shown through the BER analyses in this paper that the selection of optical modulation index of the SCM fiber optic links can be found optimally to minimize the fiber optic link noises and intermodulation distortion due to LD.

• Journal of Korea Society of Digital Industry and Information Management
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• v.13 no.2
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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.

• Journal of Convergence for Information Technology
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• v.9 no.7
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• pp.1-7
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• 2019

With the recent commercialization of the next generation of wireless 5G in everyday life, many changes have been made to organizations, industries and businesses of various sizes in various fields. However, although the improved speed and latency of 5G has improved, improvements in encryption, authentication and privacy are still required. In this paper, multiple groups of information management techniques are proposed to efficiently protect users' privacy in the heterogeneous environment of 5G. The proposed technique aims to allow distributed management of users' privacy links by clouding the privacy information generated by different heterogeneous devices to efficiently interface with different groups. Suggestion techniques process user-specific privacy information independently in a virtual space so that users can periodically synchronize their privacy information.

• Journal of KIISE:Software and Applications
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• v.26 no.8
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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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• v.6 no.1
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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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• v.6 no.5
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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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• v.10 no.2
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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.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.28B no.10
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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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• v.9 no.2
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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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.945-950
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• 2003

The link aggregation between 10GbE switches requires an advanced frame distribution method to be properly and efficiently applied. The fixed or dynamic frame distribution methods, formerly proposed, cannot fully utilize the aggregated links, where the receiving terminal only attaches to a pre-specified link among multiple physical links. A frame distribution method using tagging is proposed for the link aggregation between 10GbE switches to solve this problem. We compared the performance of the proposed method with those of the fixed and dynamic frame distribution methods. As a result, the proposed method shows a better performance when the applied load is below 0.7 and the average length of the frames is longer than 954 bytes.