• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.7
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• pp.8-17
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• 2010

Ubiquitous home refers not only to home but also to logical space, including a wide range of out-home personal devices such as mobile phones, PDAs, laptops, car navigators, and office PCs. There are certain connection barriers among the devices, such as the dynamic IP address, NAT. In a home network, various devices coexist in heterogeneous networks, such as IP, IEEE1394, PLC, Bluetooth, ZigBee, UWB, and IrDA, all of which lack interoperability due to their different physical transmission characteristics and protocols. In ubiquitous home where an unrestricted collaboration of the devices is essential to offer services that meet the users' requirements, free interoperability among the devices must be guaranteed. This paper proposes a networking model for interoperability of the heterogeneous devices in a ubiquitous home based on a virtual overlay network which hides the complicated physical network configurations and heterogeneity of the service protocols.

• Journal of the Korea Society of Computer and Information
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• v.8 no.4
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• pp.126-131
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• 2003

While the advantages of multicast delivery over multiple unicast deliveries is undeniable, the deployment of the IP multicast protocol has been limited to network domains under single administrative control. Deployment of inter-domain multicast delivery has been slow due to both technical and administrative reasons. For this reasons overlay multicasting technologies are recently proposed. We propose a End-Host Multicast Tree Protocol (EMTP) that searches two levels of the tree at a time until reaching to a leaf node and can select the nearest node that a new node try to join in the tree. Even if there is no available degree of the desirable node that a new node want to join, selecting the node as a potential parent by EMTP can reduce the number of tree switching with robustness of the tree and bring to ruduce the data delivery time.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.4
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• pp.1106-1127
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• 2012

Service oriented architecture (SOA) lends itself to model the application components to coarse-grained services in such a way that the composition of different services could be feasible. Service composition fulfills numerous service requirements by constructing composite applications with various services. As it is the case in many real-world applications, different users have diverse QoS demands issuing for composite applications. In this paper, we present a service composition framework for a typical service overlay network (SON) considering both multiple QoS constraints and load balancing factors. Moreover, a service selection algorithm based on niching technique and particle swarm optimization (PSO) is proposed for the service composition problem. It supports optimization problems with multiple constraints and objective functions, whether linear or nonlinear. Simulation results show that the proposed algorithm results in an acceptable level of efficiency regarding the service composition objective under different circumstances.

• ETRI Journal
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• v.37 no.3
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• pp.471-479
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• 2015

Traditional designs of cognitive radio (CR) focus on maximizing system throughput. In this paper, we study the joint overlay and underlay power allocation problem for orthogonal frequency-division multiple access-based CR. Instead of maximizing system throughput, we aim to maximize system energy efficiency (EE), measured by a "bit per Joule" metric, while maintaining the minimal rate requirement of a given CR system, under the total power constraint of a secondary user and interference constraints of primary users. The formulated energy-efficient power allocation (EEPA) problem is nonconvex; to make it solvable, we first transform the original problem into a convex optimization problem via fractional programming, and then the Lagrange dual decomposition method is used to solve the equivalent convex optimization problem. Finally, an optimal EEPA allocation scheme is proposed. Numerical results show that the proposed method can achieve better EE performance.

• Journal of Korea Multimedia Society
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• v.25 no.8
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• pp.1075-1084
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• 2022

Internet of Things(IoT) has become a key available technology for efficiently implementing device to device(D2D) services in various domains such as smart home, healthcare, smart city, agriculture, energy, logistics, and transportation. A lightweight publish/subscribe(Pub/Sub) messaging protocol not only establishes data dissemination pattern but also supports connectivity between IoT devices and their applications. Also, a Pub/Sub broker is deployed to facilitate data exchange among IoT devices. A scalable edge-based publish/subscribe (Pub/Sub) broker overlay networks support latency-sensitive IoT applications. In this paper, we design a hypercube grid quorum(HGQ) for distributed Pub/Sub systems based IoT applications. In designing HGQ, the network of hypercube structures suitable for the publish/subscribe model is built in the edge layer, and the proposed HGQ is designed by embedding a mesh overlay network in the hypercube. As their applications, we propose an HGQ-based mechansim for dissemination of the data of sensors or the message/event of IoT devices in IoT environments. The performance of HGQ is evaluated by analytical models. As the results, the latency and load balancing of applications based on the distributed Pub/Sub system using HGQ are improved.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.750-753
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• 2009

최근 유비쿼터스 및 모바일 환경에서 Peer-to-Peer(P2P)시스템에 대한 연구들이 활발히 진행되고 있다. 모바일 환경에서는 모바일 환경의 제약사항과 함께 이동성이라는 특징이 중요하게 고려된다. 노드의 이동에 의해서 네트워크의 주소가 변경되어 P2P 네트워크 망에서 유효하지 않은 접속 정보들이 생기고 이러한 정보들이 검색 및 P2P 시스템의 전체적인 성능을 떨어뜨리게 된다. 이 논문은 이러한 접속 정보들의 불일치를 해결하여 접속 정보를 유지하기 위한 효과적인 방법론인 이동전파 알고리즘을 제안한다. 이 알고리즘은 접속 정보의 불일치를 해결하기 위해 정보를 빠르게 처리해서 P2P 시스템의 성능을 향상하는 것을 목표로 한다. DHT 기반 P2P 시스템을 기반으로 하여 제안하는 알고리즘을 적용하여 실험을 하였으며, 그 결과로 처음 신규 발견된 정보를 재 발견하는 경우에 성능이 기존의 DHT 기반의 P2P 시스템보다 80% 향상되었음을 알 수 있다.

• Journal of KIISE:Information Networking
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• v.36 no.1
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• pp.43-49
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• 2009

The Mobile IPv6(MIPv6) has a well-known time gap of packet loss between link down and binding update. To minimize such packet loss, this paper proposes a MIPv6-based dual tunneling mechanism, which keeps exploiting the old tunnel while creating a new tunnel. Superiority of the proposed mechanism is evaluated by quantitative analysis on the lost packets and computer simulation, based on two overlay heterogeneous access networks, such as the UMTS and a WLAN.

• Journal of information and communication convergence engineering
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• v.20 no.3
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• pp.143-152
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• 2022

The ongoing adoption of 5G will increase the data traffic, throughput, multimedia services, and power consumption for future wireless applications and services, including sensor and mobile networks. Multipath fading on wireless channels also reduces the system performance and increases energy consumption. To address these issues, device-to-device (D2D) and cooperative communications have been proposed. In this study, we propose two inter-clustering models using the relay selection method to improve system performance and increase energy efficiency in cooperative D2D networks. We develop two inter-clustering models and present their respective algorithms. Subsequently, we run a computer simulation to evaluate each model's outage probability (OP) performance, throughput, and energy efficiency. The simulation results show that inter-clustering model II has the lowest OP, highest throughput, and highest energy efficiency compared with inter-clustering model I and the conventional inter-clustering-based multirelay method. These results demonstrate that inter-clustering model II is well-suited for use in 5G overlay D2D and cellular communications.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.240-249
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• 2004

For the effective IP-based service implementation in the wireless network environment, involvement of IP-related technologies in wireless networks is inevitable and globally unique IPv6 address allocation to the mobile node has become an important issue. In the 3GPP's address allocation mechanism, IPv6 address allocation procedure is performed by the GGSN, which is normally located far from the mobile nodes. This causes IPv6 address allocation time delay and traffics to be longer and increased in the core network, respectively. In this paper, we propose a new IPv6 address allocation mechanism that is performed by Node B located in RAN. The proposed IPv6 address allocation mechanism can provide IPv6 addresses to mobile nodes within a more reduced time than existing 3GPP's IPv6 address allocation mechanism, and co-operates with existing mechanism as an overlay model to improve reliability of wireless networks. And, for implementation of the proposed address allocation mechanism, it needs not to change the structure of current wireless networks except for the some functional addendum of Node B.

• Journal of Communications and Networks
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• v.6 no.3
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• pp.269-279
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• 2004

A new online multi-layer integrated routing (MLIR) scheme that combines IP (electrical) layer routing with WDM (optical) layer routing is investigated. It is a highly efficient and cost-effective routing scheme viable for the next generation integrated optical Internet. A new simplified weighted graph model for the integrated optical Internet consisted of optical routers with multi-granularity optical-electrical hybrid switching capability is firstly proposed. Then, based on the proposed graph model, we develop an online integrated routing scheme called differentiated weighted fair algorithm (DWFA) employing adaptive admission control (routing) strategies with the motivation of service/bandwidth differentiation, which can jointly solve multi-layer routing problem by simply applying the minimal weighted path computation algorithm. The major objective of DWFA is fourfold: 1) Quality of service (QoS) routing for traffic requests with various priorities; 2) blocking fairness for traffic requests with various bandwidth granularities; 3) adaptive routing according to the policy parameters from service provider; 4) lower computational complexity. Simulation results show that DWFA performs better than traditional overlay routing schemes such as optical-first-routing (OFR) and electrical-first-routing (EFR), in terms of traffic blocking ratio, traffic blocking fairness, average traffic logical hop counts, and global network resource utilization. It has been proved that the DWFA is a simple, comprehensive, and practical scheme of integrated routing in optical Internet for service providers.