• Journal of Information Processing Systems
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• v.17 no.4
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• pp.801-817
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• 2021

Network virtualization technologies have played efficient roles in deploying cloud, Internet of Things (IoT), big data, and 5G network. We have conducted a survey on network virtualization technologies, such as software-defined networking (SDN), network functions virtualization (NFV), and network virtualization overlay (NVO). For each of technologies, we have explained the comprehensive architectures, applied technologies, and the advantages and disadvantages. Furthermore, this paper has provided a summarized view of the latest research works on challenges and solutions of security issues mainly focused on DDoS attack and encryption.

• Knowledge Management Research
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• v.18 no.4
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• pp.287-306
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• 2017

This research focus on the effect of developers' participation structure in knowledge creation and knowledge sharing activities in open source software development projects. Based on preferential selection theory, hypotheses of relationship between a developers' concentration of knowledge creation/sharing activities and collaboration performance was derived. To verify the hypotheses, we use the Gini coefficient in the commit contribution of the developers (knowledge creation) and the centralization index in the repository issue network (knowledge sharing network). Using social network analysis, this paper calculates centralization index from developers in the issue boards in each repository based on data from 837 repositories in GitHub, a leading open source software development platform. As a result, instead of all developers creating and sharing knowledge equally, only a few of developers creating and sharing knowledge intensively further improve the performance of the open collaboration. In other words, a few developers predominantly providing commit and actively responding to issues raised from other developers enhance the project performance. The results of this study are expected to be used by developers who manage open source software project as a governance strategy, which could improve the performance of open collaboration.

• Journal of Mechanical Science and Technology
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• v.20 no.10
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• pp.1576-1589
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• 2006

Most of surface water ways in Egypt suffer from the infestation of aquatic weeds especially submerged ones which cause lots of problems for the open channels and the water structures such as increasing water losses, obstructing the water flow, and reducing the efficiency of the water structures. Accurate simulation of the water flow behavior in such channels is very essential for water distribution decision makers. Artificial Neural Network (ANN) has been widely utilized in the past ten years in civil engineering applications for the simulation and prediction of the different physical phenomena and has proven its capabilities in the different fields. The present study aims towards introducing the use of ANN technique to model and predict the impact of the existence of submerged aquatic weeds on the hydraulic performance of open channels. Specifically the current paper investigates utilizing the ANN technique in developing a simulation and prediction model for the flow behavior in an open channel experiment that simulates the existence of submerged weeds as branched flexible elements. This experiment was considered as an example for implementing the same methodology and technique in a real open channel system. The results of current manuscript showed that ANN technique was very successful in simulating the flow behavior of the pre-mentioned open channel experiment with the existence of the submerged weeds. In addition, the developed ANN models were capable of predicting the open channel flow behavior in all the submerged weeds' cases that were considered in the ANN development process.

• Smart Media Journal
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• v.4 no.4
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• pp.24-32
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• 2015

Recently, SDN is actively used as datacenter networks and gradually increase its applied areas. Along with this change of networking environment, research of deploying network security systems on SDN becomes highlighted. Especially, systems for detecting network flooding attacks by monitoring every packets through ports of OpenFlow switches have been proposed. However, because of the centralized management of a SDN controller which manage multiple switches, it may be substantial overhead that the attack detection system continuously monitors all the flows. In this paper, a sampling based network flooding attack detection and prevention system is proposed to reduce the overhead of monitoring packets and to achieve reasonable functionality of attack detection and prevention. The proposed system periodically takes sample packets of network flows with the given sampling conditions, analyzes the sampled packets to detect network flooding attacks, and block the attack flows actively by managing the flow entries in OpenFlow switches. As network traffic sampler, sFlow agent is used, and snort, an opensource IDS, is used to detect network flooding attack from the sampled packets. For active prevention of the detected attacks, an OpenDaylight application is developed and applied. The proposed system is evaluated on the local testbed composed with multiple OVSes (Open Virtual Switch), and the performance and overhead of the proposed system under various sampling condition is analyzed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1097-1103
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• 2015

In order to build network infrastructure to implement the aforementioned advantages enabling smart device users to work anywhere, professional support and expensive VPN devices are required. This is a barrier to supplying VPN devices to small and medium-sized institutes. To address this issue, this study aims to implement OpenVPN, OpenSSH and iproute based on the OpenWRT platform which is an embedded OS for open networks in affordable open wired/wireless gateway H/W platforms to support the inter-network VPN. In addition, the network environment can be maintained optimal by applying a "multi-queuing real-time traffic shaping technology" to VPN tunnels, although channel quality changes.

• Journal of Korea Multimedia Society
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• v.17 no.8
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• pp.988-994
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• 2014

Software Defined Network (SDN) is a new technology in computer network area which enables user to centralize control plane. The security issue is important in computer network to protect system from attackers. SYN flooding attack is one of Distributed Denial of Service attack methods which are popular to degrade availability of targeted service on Internet. There are many methods to protect system from attackers, i.e. firewall and IDS. Even though firewall is designed to protect network system, but it cannot mitigate DDoS attack well because it is not designed to do so. To improve performance of DDOS mitigation we utilize another mechanism by using SDN technology such as OpenFlow and sFlow. The methodology of sFlow to detect attacker is by capturing and sum cumulative traffic from each agent to send to sFlow collector to analyze. When sFlow collector detect some traffics as attacker, OpenFlow controller will modify the rule in OpenFlow table to mitigate attacks by blocking attack traffic. Hence, by combining sum cumulative traffic use sFlow and blocking traffic use OpenFlow we can detect and mitigate SYN flooding attack quickly and cheaply.

• 한국HCI학회:학술대회논문집
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• 2008.02b
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• pp.656-661
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• 2008

There are many sociological methodology for the study on cyber community. Especially for the online social network which is constructed by the notion of the social network, the social network analysis can be a superior methodology for the understanding of the general phenomenon and the solutions for the problematic issues. As pointed by Manuel Castells, the problem of the unification and the fragmentation, which is came after the participation and the openness, is prevailed in cyber community by its characteristics. However, computational properties that exceed the limitation of the time and space can bestow other alternatives. The Open API in the social network services that is more popular in these days is the one of those alternatives. Therefore, the purpose of this study is to investigate the problematic phenomenon of online social network and to search the solutions for those problems with the acceptance of Open API technology.

• Journal of Korea Technology Innovation Society
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• v.8 no.3
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• pp.1139-1156
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• 2005

The explosive growth in wireless networks and Internet services has created considerable demand for mobile Internet services based on the mobile phone. Mobile Internet has become the new business model in telecommunication market, therefore the open network policy for mobile Internet has been formulated and implemented by the government in Korea. In spite of the open network policy for mobile Internet, there has been no systematic analysis of the various interconnection issues, including pricing, in mobile Internet network. This paper aims to suggest the interconnection pricing methods for mobile Internet network by reviewing the current pricing models for various communications services, and adapting them to mobile Internet communications circumstances. Results of this paper can be used as a guideline for government policy directions and management decision making after the introduction of the open network policy for mobile Internet.

• Journal of the Korea Society of Computer and Information
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• v.4 no.3
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• pp.107-113
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• 1999

Banking and financial areas are facing on social upheavals by a rapidly advanced Open Network such as Internet, and the crest of a digital boom in the economic side for the 21th century. Electronic banking services has been remarkably changed from the Closed Network into the Open Network which is motivated by the low-cost internet services. This Open Network leads clients to choose banks that offer the best services and goods on the basis of the internet market. Therefore, capability of coping with clients' needs will be rising as one of the main strategies for competitive internet banking system in the near future. For this reason this thesis focuses on issues for banking services that internet influences, internet banking strategy of a developed bank, and expanding services and goods marketing through the internet.

• ETRI Journal
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• v.41 no.4
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• pp.473-482
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• 2019

High availability and reliability have been considered promising requirements for the support of seamless network services such as real-time video streaming, gaming, and virtual and augmented reality. Increased availability can be achieved within a local area network with the use of the virtual router redundancy protocol that utilizes backup routers to provide a backup path in the case of a master router failure. However, the network may still lose a large number of packets during a failover owing to a late failure detections and lazy responses. To achieve an efficient failover, we propose the implementation of fast detection with virtual router redundancy protocol (FDVRRP) in which the backup router quickly detects a link failure and immediately serves as the master router. We implemented the FDVRRP using open neutralized network operating system (OpenN2OS), which is an open-source-based network operating system. Based on the failover performance test of OpenN2OS, we verified that the FDVRRP exhibits a very fast failure detection and a failover with low-overhead packets.