• 한국멀티미디어학회논문지
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• 제25권10호
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• pp.1404-1415
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• 2022

The 2-dimensional arrangement method of nodes has been used in most of RF (Radio Frequency) based communication network simulations. However, this method is not useful for the an none-obstacle 3-dimensional space networks in which the propagation delay speed in communication is very slow and, moreover, the values of performance factors such as the communication speed and the error rate change on the depth of node. Such a typical example is an underwater communication network. The 2-dimensional arrangement method is also not useful for the RF based network like some WSNs (Wireless Sensor Networks), IBSs (Intelligent Building Systems), or smart homes, in which the distance between nodes is short or some of nodes can be arranged overlapping with their different heights in similar planar location. In such cases, the 2-dimensional network simulation results are highly inaccurate and unbelievable so that they lead to user's erroneous predictions and judgments. For these reasons, in this paper, we propose a method to place uniformly and randomly communication nodes in 3-dimensional network space, making the wireless link with neighbor node possible. In this method, based on the communication rage of the node, blocks are generated to construct the 3-dimensional network and a node per one block is generated and placed within a block area. In this paper, we also introduce an algorithm based on this method and we show the performance results and evaluations on the average time in a node generation and arrangement, and the arrangement time and scatter-plotted visualization time of all nodes according to the number of them. In addition, comparison with previous studies is conducted. As a result of evaluating the performance of the algorithm, it was found that the processing time of the algorithm was proportional to the number of nodes to be created, and the average generation time of one node was between 0.238 and 0.28 us. ultimately, There is no problem even if a simulation network with a large number of nodes is created, so it can be sufficiently introduced at the time of simulation.

• Journal of information and communication convergence engineering
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• 제7권2호
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• pp.185-192
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• 2009

In wireless mesh networks multi-rate technology environment, a mesh node can dynamically modify the data transmission rate on a particular link, in response to link distance, or more accurately, the perceived SNR ratio between neighbor nodes. In such networks, existing route selection schemes use a link quality metric. Thus, these schemes may easily result in the network being overloaded. In this paper, a new route metric is proposed; it considers both per-hop service delay and link quality at mesh nodes. In addition, the Load-Aware AODV (LA-AODV) protocol using the proposed metric is presented. The performance evaluation is performed by simulation using the OPNET simulator. It is demonstrated that the LA-AODV protocol outperforms the existing routing protocols using other existing route metrics in multi-rate WMN environment.

• Journal of Communications and Networks
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• 제8권4호
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• pp.410-421
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• 2006

In this work, we propose an analytic framework for dimensioning the link capacity of broadband access networks which provide universal broadband access services to a diverse kind of customers such as patient and impatient customers. The proposed framework takes into account the flow-level quality of service (QoS) of a connection as well as the packet-level QoS, via which a simple and systematic provisioning and operation of the network are provided. To that purpose, we first discuss the necessity of flow-aware network dimensioning by reviewing the networking technologies of the current and future access network. Next, we propose an analytic model for dimensioning the link capacity for an access node of broadband convergence networks which takes into account both the flow and packet level QoS requirements. By carrying out extensive numerical experiment for the proposed model assuming typical parameters that represent real network environment, the validity of the proposed method is assessed.

• 한국산업융합학회 논문집
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• 제6권4호
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• pp.339-345
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• 2003

The purpose of this thesis is to develop a simulation model to estimate link travel speed applicable to urban street transportation planning for interrupted traffic flow, influenced by signalized intersection. This link travel speed model is expected to be a better and more than previous studies.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2013년도 추계학술발표대회
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• pp.400-401
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• 2013

Mobility in a network causes link disconnections and link recovery is vital for reliability of a network. A link failure affects all the preceding nodes on a damaged routing path; creates communication delay, throughput degradation, and congestion. This paper proposes link recovery mechanisms in CCN based networks. Packet overhearing is used to update neighboring nodes information. The recovery is done by forwarding node resulting in low control overhead, and better efficiency. The proposed mechanisms increase overall performance of a typical CCN and simulation results show that our proposed scheme works very well in densely populated networks with high mobility.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권3호
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• pp.816-839
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• 2023

In a random vector functional link (RVFL) network, shortcomings such as local optimal stagnation and decreased convergence performance cause a reduction in the accuracy of illumination correction by only inputting the weights and biases of hidden neurons. In this study, we proposed an improved regularized random vector functional link (RRVFL) network algorithm with an optimized grey wolf optimizer (GWO). Herein, we first proposed the moth-flame optimization (MFO) algorithm to provide a set of excellent initial populations to improve the convergence rate of GWO. Thereafter, the MFO-GWO algorithm simultaneously optimized the input feature, input weight, hidden node and bias of RRVFL, thereby avoiding local optimal stagnation. Finally, the MFO-GWO-RRVFL algorithm was applied to ameliorate the performance of illumination correction of various test images. The experimental results revealed that the MFO-GWO-RRVFL algorithm was stable, compatible, and exhibited a fast convergence rate.

• International Journal of Reliability and Applications
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• 제9권1호
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• pp.1-5
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• 2008

A heuristic algorithm for reliability optimization of a distributed network system is developed so that the reliability of a large system can be determined efficiently. This heuristic bases on the determination of maximal reliability set of maximum node capacity, maximal link reliability and maximal node degree.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2008년도 추계학술발표대회
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• pp.1314-1315
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• 2008

Recent research work has unearthed that multi-radio multi-channel wireless mesh networks offer considerable capacity gains over single-radio wireless mesh networks. In this paper, we present a new routing metric for multi-radio multi-channel wireless mesh networks. The goal of the metric is to choose multiple link/node disjoint paths between a source and destination node that, when used concomitantly, impart high end-to-end throughput. The proposed metric selects high fidelity paths that will produce elevated throughput with maximum fault tolerance.

• 한국정보시스템학회지:정보시스템연구
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• 제9권1호
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• pp.27-44
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• 2000

The structure of neural networks is represented by a weighted directed graph with nodes representing units and links representing connections. Each link is assigned a numerical value representing the weight of the connection. In learning process, the values of weights are adjusted by errors. Following experiment results, the interval of adjusting weights, that is, epoch size influenced neural networks＇ performance. As epoch size is larger than a certain size, neural networks＇performance decreased drastically. And the number of hidden layer＇s node also influenced neural networks＇performance. The networks＇performance decreased as hidden layers have more nodes and then increased at some number of hidden layer＇s node. So, in implementing of neural networks the epoch size and the number of hidden layer＇s node should be decided by systematic methods, not empirical or heuristic methods.

• 한국멀티미디어학회논문지
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• 제10권10호
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• pp.1347-1355
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• 2007

센서 네트워크는 관심 지역을 감지하도록, 작은 센서를 배치하여 센서가 감지한 작업을 수집하여 사용자에게 제공하는 기능을 가진다. 감지 작업을 보고할 때 노드간의 라우팅 경로는, 베이스 스테이션의 요청이 있는 경우 경로 설정이 이루어지는데, 이 때 경로는 노드의 한정된 에너지를 고려하여 에너지 소모를 최소화하는 형태로 이루어진다. 또한 노드가 가지는 낮은 용량, 한정된 자원, 이동성 등의 이유로, 감지 작업을 보고할 경우 베이스 스테이션의 요청에 따라 라우팅 경로를 재설정하게 된다. 본 논문에서는 싱크(Sink) 노드가 감지작업을 요청할 경우, 각 노드는 자신의 링크 정보를 보고하게 되고, 싱크 노드는 전체 토폴로지 정보를 수집하고 관리하여 각 노드와의 협상 없이 라우팅 경로를 설정한다. 그러면 설정된 경로의 손실이 발생하는 경우와 지속적인 감시 작업등의 상황에서 노드간의 협상을 통한 라우팅 경로 설정 과정을 거치지 않고 자신의 라우팅 경로 정보를 이용하여 주경로 및 대체 경로를 쉽게 찾을 수 있게 된다. 싱크 노드에게 보고하는 노드의 연결 정보는 각 노드가 주기적으로 신호를 주고받아 보관하므로 경로 정보를 수집하는데 소요되는 부하를 줄일 수 있다. 본 논문에서 제안하는 라우팅 알고리즘은, 경로 설정에 필요한 라우팅 메시지를 초기에 주고받아 경로를 설정함으로써 설정된 경로가 실패되더라도 노드가 가지는 토폴로지 정보를 이용하여 대체 경로를 설정함으로써, 경로 설정에 필요한 라우팅 메시지를 줄이게 되고 재경로 탐색이 쉽게 이루어지게 된다. 이는 노드의 소실이 많은 지역이나 모니터링 환경에 적합하다.