• The KIPS Transactions:PartC
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• v.13C no.3 s.106
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• pp.303-310
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• 2006

This paper is to execute a study for characteristic analysis of synchronization clock and maximum network node number with various clock states, normal, SPT, LPT, in NG-SDH networks. Through the simulations, maximum network node numbers showed from 42 to 38 nodes in normal state. In SPT state, maximum network node numbers, when the last NE network applied to only SPT state, presented from 19 to 4 nodes, much less than normal state. Node numbers to meet specification in case of occurrence of SPT state in all NE networks decreased greatly. In LPT state, all maximum node numbers, when the last NE network applied to only LPT state, presented more than 50 nodes, and the results in case of occurrence of LPT state in all NE networks were also identified. However, node numbers to meet specification in case of LPT state in all DOTS networks were few large with difference between LPT and normal or SPT state.

• Journal of Korea Multimedia Society
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• v.20 no.8
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• pp.1357-1368
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• 2017

Sensor networks are used in various fields such as marine, defense, and smart home etc. Among the components of the sensor network, the sensor node collects sensor data, as one of the representative sensor network roles, and the sensor node makes a greate influence on the overall performance of the sensor network. Therefore, how to design the sensor node is an important issue in the sensor network field. However, the research on the sensor network architecture suitable for the sensor network installation environment has been made more important than the research on how to configure the sensor node. In this paper, we propose to identify elements to be considered for designing a sensor node that makes a large influence on the performance of the sensor network, and to easily implement the sensor node through the state transition model based on these elements.

• Smart Structures and Systems
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• v.11 no.3
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• pp.261-282
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• 2013

Structural health monitoring (SHM) is an application area of Wireless Sensor Networks (WSNs) which usually needs high data communication rate to transfer a large amount of monitoring data. Traditional sink node can only process data from one communication channel at the same time because of the single radio chip structure. The sink node constitutes a bottleneck for constructing a high data rate SHM application giving rise to a long data transfer time. Multi-channel communication has been proved to be an efficient method to improve the data throughput by enabling parallel transmissions among different frequency channels. This paper proposes an 8-radio integrated sink node design method based on Field Programmable Gate Array (FPGA) and the time synchronization mechanism for the multi-channel network based on the proposed sink node. Three experiments have been performed to evaluate the data transfer ability of the developed multi-radio sink node and the performance of the time synchronization mechanism. A high data throughput of 1020Kbps of the developed sink node has been proved by experiments using IEEE.805.15.4.

• Journal of KIISE:Information Networking
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• v.31 no.5
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• pp.482-489
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• 2004

Paging extensions for Mobile IP was proposed to avoid unnecessary registration signaling overhead of Mobile IP. In order to support the paging function in Mobile IP, the slates of a mobile node arc divided into active on, active off, idle. The active on state means when any incoming or outgoing data session arrives to a mobile node. After data session is completed, the state of the motile node is changed into active off from active on. At this moment, the active timer starts to be operated. If the active timer expires, the mobile node moves to idle state. If a mobile node has very frequently data sessions at the same cell, the mobile node is better to move slowly into idle state. The other way, if the mobile node very frequently moves into new cell area and receives or sends little data, the mobile node is better to move earlier into idle state. In this raper, the active timer is adaptively set by the mobile nodes traffic and mobility characteristics and the paging scheme using this active timer is proposed to reduce the location registration cost.

• International Journal of Control, Automation, and Systems
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• v.6 no.6
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• pp.904-914
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• 2008

An action-selection-mechanism(ASM) has been proposed to work as a fully connected finite state machine to deal with sequential behaviors as well as to allow a state in the task program to migrate to any state in the task, in which a primitive node in association with a state and its transitional conditions can be easily inserted/deleted. Also, such a primitive node can be learned by a shortest path-finding-based reinforcement learning technique. Specifically, we define a behavioral motivation as having state-dependent value as a primitive node for action selection, and then sequentially construct a network of behavioral motivations in such a way that the value of a parent node is allowed to flow into a child node by a releasing mechanism. A vertical path in a network represents a behavioral sequence. Here, such a tree for our proposed ASM can be newly generated and/or updated whenever a new behavior sequence is learned. To show the validity of our proposed ASM, experimental results of a mobile robot performing the task of pushing- a- box-in to- a-goal(PBIG) will be illustrated.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.8
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• pp.3789-3808
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• 2017

This paper studies a multi-antenna wireless relay network in the presence of a jammer. In this network, the source node transmits signals to the destination node through a multi-antenna relay node which adopts the amplify-and-forward scheme, and the jammer attempts to inject additive signals on all antennas of the relay node. With the linear beamforming scheme at the relay node, this network can be modeled as an equivalent Gaussian arbitrarily varying channel (GAVC). Based on this observation, we deduce the mathematical closed-forms of the capacities for two special cases and the suboptimal achievable rate for the general case, respectively. To reduce complexity, we further propose an optimal structure of the beamforming matrix. In addition, we present a second order cone programming (SOCP)-based algorithm to efficiently compute the optimal beamforming matrix so as to maximize the transmission rate between the source and the destination when the perfect channel state information (CSI) is available. Our numerical simulations show significant improvements of our propose scheme over other baseline ones.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.11
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• pp.1131-1135
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• 2014

This paper proposes the enhanced faulty node detection scheme with hybrid algorithm using Markov-chain model on BCH (Bose-Chaudhuri-Hocquenghem) code in naval distributed control networked systems. The probabilistic model-driven approach, on Markov-chain model, in this paper uses the faulty weighting interval factors, which are based on the BCH code. In this scheme, the master node examines each slave-nodes continuously using three defined states : Good, Warning, Bad-state. These states change using the probabilistic calculation method. This method can improve the performance of detecting the faulty state node more efficiently. Simulation results show that the proposed method can improve the accuracy in faulty node detection scheme for real-time naval distributed control networked systems.

• ETRI Journal
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• v.38 no.4
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• pp.714-723
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• 2016

Considerable attention has been given to processing graph data in recent years. An efficient method for computing the node proximity is one of the most challenging problems for many applications such as recommendation systems and social networks. Regarding large-scale, mutable datasets and user queries, top-k query processing has gained significant interest. This paper presents a novel method to find top-k answers in a node proximity search based on the well-known measure, Personalized PageRank (PPR). First, we introduce a distribution state transition graph (DSTG) to depict iterative steps for solving the PPR equation. Second, we propose a weight distribution model of a DSTG to capture the states of intermediate PPR scores and their distribution. Using a DSTG, we can selectively follow and compare multiple random paths with different lengths to find the most promising nodes. Moreover, we prove that the results of our method are equivalent to the PPR results. Comparative performance studies using two real datasets clearly show that our method is practical and accurate.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.5
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• pp.1-15
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• 1993

In DQDB networks, the bandwidth can be increased considerably be using the EN(Erasure Node) algorithms and DR(Destination Release) algorithms. However, the important issue in implementing them is using method of extra capacity fairly. To improve it, this paper proposes AEN(Adaptive Erasure Node) algorithm which erasure function is activated by network traffic load. Its functional architecture consists of SESM, RCSM, LMSM in addition to the basic DQDB state machines (DQSM, RQM). The SESM and RCSM state machines are placed in front of the DQSM and RQM state machines in order for the node to take advantage of the newly cleared slots. This paper also presents some simulation results showing the effect of AEN algorithm on access delay, throughput and segment erasing ratio in the single and multiple priority networks. The results show that the AEN algorithm offer the better performance characteristics than existing algorithms under overload conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1329-1338
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• 2011

This paper proposes an algorithm and hardware architecture for a broadcast communication which has the worst bottleneck among multiprocessor using distributed memory architectures. In conventional systems, collective communication is converted into point-to-point communications by MPI library cell without considering the state of communication port of each processing node which represents the processing node is in busy state or free state. If conflicting point-to-point communication occurs during broadcast communication, the transmitting speed for broadcast communication is decreased. Thus, this paper proposed an algorithm which determines the order of point-to-point communications for broadcast communication according to the state of each processing node. According to the state of each processing node, the proposed algorithm decreases total broadcast communication time by transmitting message preferentially to the processing node with communication port in free state. The proposed MPI unit for broadcast communication is evaluated by modeling it with systemC. In addition, it achieved a highly improved performance for broadcast communication up to 78% with 16 nodes. This result shows the proposed algorithm is useful to improving total performance of MPSoC.