• Title/Summary/Keyword: Large-scale network

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Delay Control using Fast TCP Prototype in Internet Communication (인터넷 통신에서 고속 TCP 프로토타입을 이용한 지연 제어)

  • 나하선;김광준;나상동
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.7 no.6
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    • pp.1194-1201
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    • 2003
  • Measurements of network traffic have shown that self-similarity is a ubiquitous phenomenon spanning across diverse network environments. We have advance the framework of multiple time scale congestion control and show its effectiveness at enhancing performance for fast TCP prototype control. In this paper, we extend the fast TCP prototype control framework to window-based congestion control, in particular, TCP. This is performed by interfacing TCP with a large time scale control module which adjusts the aggressiveness of bandwidth consumption behavior exhibited by TCP as a function of "large time scale" network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by RTT. Performance evaluation of fast TCP prototype is facilitated by a simulation bench-mark environment which is based on physical modeling of self-similar traffic. We explicate out methodology for discerning and evaluating the impact of changes in transport protocols in the protocol stack under self-similar traffic conditions. We discuss issues arising in comparative performance evaluation under heavy-tailed workload. workload.

Differences in Large-scale and Sliding-window-based Functional Networks of Reappraisal and Suppression

  • Jun, Suhnyoung;Lee, Seung-Koo;Han, Sanghoon
    • Science of Emotion and Sensibility
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    • v.21 no.3
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    • pp.83-102
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    • 2018
  • The process model of emotion regulation suggests that cognitive reappraisal and expressive suppression engage at different time points in the regulation process. Although multiple brain regions and networks have been identified for each strategy, no articles have explored changes in network characteristics or network connectivity over time. The present study examined (a) the whole-brain network and six other resting-state networks, (b) their modularity and global efficiency, which is an index of the efficiency of information exchange across the network, (c) the degree and betweenness centrality for 160 brain regions to identify the hub nodes with the most control over the entire network, and (d) the intra-network and inter-network functional connectivity (FC). Such investigations were performed using a traditional large-scale FC analysis and a relatively recent sliding window correlation analysis. The results showed that the right inferior orbitofrontal cortex was the hub region of the whole-brain network for both strategies. The present findings of temporally altering functional activity of the networks revealed that the default mode network (DMN) activated at the early stage of reappraisal, followed by the task-positive networks (cingulo-opercular network and fronto-parietal network), emotion-processing networks (the cerebellar network and DMN), and sensorimotor network (SMN) that activated at the early stage of suppression, followed by the greater recruitment of task-positive networks and their functional connection with the emotional response-related networks (SMN and occipital network). This is the first study that provides neuroimaging evidence supporting the process model of emotion regulation by revealing the temporally varying network efficiency and intra- and inter-network functional connections of reappraisal and suppression.

An Energy Efficient Group-Based Cluster Key Management for Large Scale Sensor Networks (대규모 센서 네트워크에서 그룹을 기반으로 한 에너지 효율적인 클러스터키 관리 방안)

  • Kim, Jin-Su
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.11
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    • pp.5487-5495
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    • 2012
  • The important issue that applies security key are secure rekeying, processing time and cost reduction. Because of sensor node's limited energy, energy consumption for rekeying affects lifetime of network. Thus it is necessary a secure and efficient security key management method. In this paper, I propose an energy efficient group-based cluster key management (EEGCK) in the large scale sensor networks. EEGCK uses five security key for efficient key management and different polynomial degree using security fitness function of sector, cluster and group is applied for rekeying and security processing. Through both analysis and simulation, I also show that proposed EEGCK is better than previous security management method at point of network energy efficiency.

Estimation Modelling of Energy Consumption and Anti-greening Impacts in Large-Scale Wired Access Networks (대규모 유선 액세스 네트워크 환경에서 에너지 소모량과 안티그리닝 영향도 추정 모델링 기법)

  • Suh, Yuhwa;Kim, Kiyoung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.8
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    • pp.928-941
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    • 2016
  • Energy consumption of today's wired data networks is driven by access networks. Today, green networking has become a issue to reduce energy wastes and $CO_2$ emission by adding energy managing mechanism to wired data networks. However, energy consumption and environmental impacts of wired access networks are largely unknown. In addition, there is a lack of general and quantitative valuation basis of energy use of large-scale access networks and $CO_2$ emissions from them. This paper compared and analyzed limits of existing models estimating energy consumption of access networks and it proposed a model to estimate energy consumption of large-scale access networks by top-down approach. In addition, this work presented models that assess environmental(anti-greening) impacts of access networks using results from our models. The performance evaluation of the proposed models are achieved by comparing with previous models based on existing investigated materials and actual measured values in accordance with real cases.

Modeling and Implementation of Firewall and IPS for Security Simulation on Large-scale Network Using SSFNet (SSFNet을 이용한 대규모 네트워크상에서의 보안 시뮬레이션을 위한 방화벽과 IPS모듈의 모델링 및 구현)

  • Kim, Yong-Tak;Kwon, Oh-Jun;Kim, Tai-Suk
    • Journal of Korea Multimedia Society
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    • v.9 no.8
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    • pp.1037-1044
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    • 2006
  • It's difficult to check cyber attacks and the performance of a security system in a real large-scale network. Generally, a new security system or the effect of a new security attack are checked by simulation. We use SSFNet to simulate our security system and cyber attack. SSFNet is an event-driven simulation tools based on process, which has a strength to be capable of expressing a large-scale network. But it doesn't offer any API's which can manipulate not only the related function of security but also the packet. In this paper, we developed a firewall and IPS class, used for a security system, and added to them components of SSFNet. The firewall is modelled a security system based on packet filtering. We checked the function of the firewall and the IPS with network modelled as using our SSFNet. The firewall blocks packets through rules of an address and port of packets. The result of this simulation shows that we can check a status of packets through a log screen of IPS installed in a router and confirm abnormal packet to be dropped.

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A Study of Developing Variable-Scale Maps for Management of Efficient Road Network (효율적인 네트워크 데이터 관리를 위한 가변-축척 지도 제작 방안)

  • Joo, Yong Jin
    • Journal of Korean Society for Geospatial Information Science
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    • v.21 no.4
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    • pp.143-150
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    • 2013
  • The purpose of this study is to suggest the methodology to develop variable-scale network model, which is able to induce large-scale road network in detailed level corresponding to small-scale linear objects with various abstraction in higher level. For this purpose, the definition of terms, the benefits and the specific procedures related with a variable-scale model were examined. Second, representation level and the components of layer to design the variable-scale map were presented. In addition, rule-based data generating method and indexing structure for higher LoD were defined. Finally, the implementation and verification of the model were performed to road network in study area (Jeju -do) so that the proposed algorithm can be practical. That is, generated variable scale road network were saved and managed in spatial database (Oracle Spatial) and performance analysis were carried out for the effectiveness and feasibility of the model.

Utilization of Heat from Waste-Incineration Facility for Heating Large-Scale Horticultural Facilities (소각시설 여열을 이용한 대규모 시설원예 단지의 난방 시스템 적용 가능성 평가)

  • Lee, Jaeho;Hyun, Intak;Lee, Kwang Ho
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.27 no.8
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    • pp.418-425
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    • 2015
  • The Korean government plans to establish large-scale horticultural facilities using reclaimed land to improve the competitiveness of the national agricultural sector at the government level. One of the most significant corresponding problems is the ongoing dependence of these facilities on fossil fuel, whereby constant heating is necessary during the winter season to provide the necessary breeding conditions for greenhouse crops. In particular, high-level energy consumption is incurred from the use of heating-related coverings with large heat-transmission coefficients such as those composed of vinyl and glass. This study investigated the potential applicability of waste-incineration heat for use in large-scale horticultural facilities by evaluating the hot-water temperature, heat loss, and available greenhouse area as functions of the distance between the incineration facility and the greenhouse. In conclusion, waste-incineration heat from a HDPE pipe can heat a horticultural facility of 10 ha if the distance is less than 8 km.

Impact of Human Mobility on Social Networks

  • Wang, Dashun;Song, Chaoming
    • Journal of Communications and Networks
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    • v.17 no.2
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    • pp.100-109
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    • 2015
  • Mobile phone carriers face challenges from three synergistic dimensions: Wireless, social, and mobile. Despite significant advances that have been made about social networks and human mobility, respectively, our knowledge about the interplay between two layers remains largely limited, partly due to the difficulty in obtaining large-scale datasets that could offer at the same time social and mobile information across a substantial population over an extended period of time. In this paper, we take advantage of a massive, longitudinal mobile phone dataset that consists of human mobility and social network information simultaneously, allowing us to explore the impact of human mobility patterns on the underlying social network. We find that human mobility plays an important role in shaping both local and global structural properties of social network. In contrast to the lack of scale in social networks and human movements, we discovered a characteristic distance in physical space between 10 and 20 km that impacts both local clustering and modular structure in social network. We also find a surprising distinction in trajectory overlap that segments social ties into two categories. Our results are of fundamental relevance to quantitative studies of human behavior, and could serve as the basis of anchoring potential theoretical models of human behavior and building and developing new applications using social and mobile technologies.

A Survey on Key Management Strategies for Different Applications of Wireless Sensor Networks

  • Raazi, Syed Muhammad Khaliq-Ur-Rahman;Lee, Sung-Young
    • Journal of Computing Science and Engineering
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    • v.4 no.1
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    • pp.23-51
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    • 2010
  • Wireless Sensor Networks (WSN) have proved to be useful in applications that involve monitoring of real-time data. There is a wide variety of monitoring applications that can employ Wireless Sensor Network. Characteristics of a WSN, such as topology and scale, depend upon the application, for which it is employed. Security requirements in WSN vary according to the application dependent network characteristics and the characteristics of an application itself. Key management is the most important aspect of security as some other security modules depend on it. We discuss application dependent variations in WSN, corresponding changes in the security requirements of WSN and the applicability of existing key management solutions in each scenario.