• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• v.10 no.1
• /
• pp.83-93
• /
• 2006

This paper introduces rule-based reasoning (RBR) based self-recovery system for network fault in ubiquitous computing. This system is fault management system for fault recovery of rule-based for self-recovery in ubiquitous computing environment. We proposed rules of network fault recovery applied the system as a distinguished reason of network fault. And, in this paper, the network fault self-recovery system proved the rules that applied each situatpion through the simulation.

• Structural Monitoring and Maintenance
• /
• v.7 no.2
• /
• pp.109-124
• /
• 2020

Benefiting from the massive monitoring data collected by the Structural health monitoring (SHM) system, scholars can grasp the complex environmental effects and structural state during structure operation. However, the monitoring data is often missing due to sensor faults and other reasons. It is necessary to study the recovery method of missing monitoring data. Taking the structural temperature monitoring data of Nanjing Dashengguan Yangtze River Bridge as an example, the long short-term memory (LSTM) network-based recovery method for missing structural temperature data is proposed in this paper. Firstly, the prediction results of temperature data using LSTM network, support vector machine (SVM), and wavelet neural network (WNN) are compared to verify the accuracy advantage of LSTM network in predicting time series data (such as structural temperature). Secondly, the application of LSTM network in the recovery of missing structural temperature data is discussed in detail. The results show that: the LSTM network can effectively recover the missing structural temperature data; incorporating more intact sensor data as input will further improve the recovery effect of missing data; selecting the sensor data which has a higher correlation coefficient with the data we want to recover as the input can achieve higher accuracy.

• 한국정보통신설비학회:학술대회논문집
• /
• 2009.08a
• /
• pp.285-288
• /
• 2009

The emergency recovery scheme in time of a disaster or accident up to now has been focused on how to build a backup for the public service or communication network in national scale, also, all the mobile operators have done as recovery scheme for the equipment failure in their network was to make a backup copy of billing data or package data, and they have usually studied only on the backup and failure recovery scheme in the circuit-switched network. However, since it has become more probable recently that a disaster or accident could occur in the switching office buildings, a recovery scheme in time of the failure of these entire switching offices became necessary. The purpose of this paper is to propose various recovery schemes, and by having checkups on many issues that could arise while carrying out these schemes, it presents the best solution for each issue. Moreover, it presents the future tasks that need to be studied as well as initial study directions.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.47 no.2
• /
• pp.50-54
• /
• 2010

Soft recovery (SR) quasi-resonant converter (QRC) including a Folding snubber network (FSN) is introduced. It is obtained by combining normal quasi-resonant converter with folding snubber network of which the surrounding components are composed of passive devices only (diodes and capacitors). The reverse recovery loss of the main rectifier diode is eliminated by this method utilizing quasi resonance with Folding snubber network. By realizing soft switching condition, the proposed converter has PWM capability with high efficiency and is suitable for high output current and high power DC to DC converter application.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.13 no.9
• /
• pp.4572-4586
• /
• 2019

Mobile Edge Computing (MEC) and Information-Centric Networking (ICN) are essential network architectures for the future Internet. The advantages of MEC and ICN such as computation and storage capabilities at the edge of the network, in-network caching and named-data communication paradigm can greatly improve the quality of video streaming applications. However, the packet loss in wireless network environments still affects the video streaming performance and the existing loss recovery approaches in ICN does not exploit the capabilities of MEC. This paper proposes a Deep Learning based Loss Recovery Mechanism (DL-LRM) for video streaming over MEC based ICN. Different with existing approaches, the Forward Error Correction (FEC) packets are generated at the edge of the network, which dramatically reduces the workload of core network and backhaul. By monitoring network states, our proposed DL-LRM controls the FEC request rate by deep reinforcement learning algorithm. Considering the characteristics of video streaming and MEC, in this paper we develop content caching detection and fast retransmission algorithm to effectively utilize resources of MEC. Experimental results demonstrate that the DL-LRM is able to adaptively adjust and control the FEC request rate and achieve better video quality than the existing approaches.

• Journal of Korea Multimedia Society
• /
• v.24 no.3
• /
• pp.431-439
• /
• 2021

Since the sensor nodes are randomly arranged in the region of interest, it may happen that the sensor network area is separated or there is no sensor node in some area. In addition, after the sensor nodes are deployed in the sensor network, a coverage hole may occur due to the exhaustion of energy or physical destruction of the sensor nodes. The coverage hole can greatly affect the overall performance of the sensor network, such as reducing the data reliability of the sensor network, changing the network topology, disconnecting the data link, and worsening the transmission load. Therefore, sensor network coverage hole recovery has been studied. Existing coverage hole recovery studies present very complex geometric methods and procedures in the two-step process of finding a coverage hole and recovering a coverage hole. This study proposes a method for discovering and recovering a coverage hole in a sensor network, discovering that the sensor node is a boundary node by itself, and determining the location of a mobile node to be added. The proposed method is expected to have better efficiency in terms of complexity and message transmission compared to previous methods.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.9 no.12
• /
• pp.5116-5134
• /
• 2015

In this paper, due to the network security defense is mainly static defense, a dynamic classification network security defense strategy model is proposed by analyzing the security situation of complex computer network. According to the network security impact parameters, eight security elements and classification standard are obtained. At the same time, the dynamic classification algorithm based on fuzzy theory is also presented. The experimental analysis results show that the proposed model and algorithm are feasible and effective. The model is a good way to solve a safety problem that the static defense cannot cope with tactics and lack of dynamic change.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.11
• /
• pp.5200-5222
• /
• 2017

The separation of control plane and data plane in Software Defined Network (SDN) makes it flexible to control the network behavior, while also causes some inconveniences to the link failure recovery due to the delay between fail point and the controller. To avoid delay and packet loss, pre-defined backup paths are used to reroute the disrupted flows when failure occurs. However, it may introduce large overhead to build and maintain these backup paths and is hard to dynamically construct backup paths according to the network status so as to avoid congestion during rerouting process. In order to realize congestion aware fast link failure recovery, this paper proposes a novel method which installs multi backup paths for every link via source routing and per-hop-tags and spread flows into different paths at fail point to avoid congestion. We carry out experiments and simulations to evaluate the performance of the method and the results demonstrate that our method can achieve congestion aware fast link failure recovery in SDN with a very low overhead.

• Journal of Korea Game Society
• /
• v.15 no.1
• /
• pp.171-184
• /
• 2015

Looking at the existing game-related research, innumerable researches such as game acceptance, user satisfaction, continuance intention, wold-of-mouse intention have been carried out. However, there was no cases that applying the concept of service recovery in game researches. The purpose of this study is to evaluate the impact on the characteristic of the mobile social network game that based on domestic mobile social network game platform which focusing on KakaoTalk games on the service recovery. In addition, the study analyzed the characteristic factors of mobile social network game on the basis of Organizational Equity Theory and Innovation Diffusion Theory to identified the causal relationship between those factors and service recovery. As a result, except the independent variable-compatibility, all of the characteristics factors of mobile social network game showed direct or indirect effects on service recovery. The results of this study are expected as a reference for presenting a new business model, reducing risk factors and enriching the related research of the gaming industry.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.29 no.7B
• /
• pp.650-659
• /
• 2004

Domestic wireless network environment is changing rapidly while adapting to meet service requirements of users and growth of market. As a result, reliable data transmission using TCP is also expected to increase. Since TCP assumes that it is used in wired networt TCP suffers significant performance degradation over wireless network where packet losses are not always result of network congestion. Especially RTO imposes a great performance degradation of TCP. In this paper, we propose DAC$^{＋}$ and EFR in order to prevent performance degradation by quickly detecting and recovering loss without RTO during fast recovery. Compared with TCP NewReno, proposed scheme shows improvements in steady-state in terms of higher fast recovery Probability and reduced response time.