• The KIPS Transactions:PartC
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• v.15C no.2
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• pp.93-102
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• 2008

The network weather map and bandwidth time-series graph are popularly used to understand the current and past traffic condition of NSP, ISP, and enterprise networks. These systems collect traffic performance data from a SNMP agent running on the network devices such as routers and switches, store the gathered information into a DB, and display the network performance status in the form of a time-series graph or a network weather map using Web user interface. Most of current enterprise networks are constructed in the form of a hierarchical tree-like structure with multi-Gbps Ethernet links, which is quietly different from the national or world-wide backbone network structure. This paper focuses on the network weather map for current enterprise network. We start with the considering points in developing a network weather map system suitable for enterprise network. Based on these considerings, this paper proposes the best way of using SNMP in constructing a network weather map system. To prove our idea, we designed and developed a network weather map system for our campus network, which is also described in detail.

• Journal of Internet Computing and Services
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• v.22 no.4
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• pp.123-134
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• 2021

This paper suggests that the Internet is not free through analysis of U.S. Internet history and lawsuits related to the Charter merger in 2016. Generally speaking, the players in internet connectivity market agree to Non-Disclosure Agreement, when connecting their facilities and networks each other. So, I adopted the case study & analysis as research methodologies due to limitation of collecting the transaction data between them. The former finds that Internet access has never been free in U.S Internet history. As we know, some including Content Providers(CPs) argue that the Internet is a free network and there are many cases to use the internet for free, so they came to conclusion that ISPs have no right to charge the users like CPs. This study refutes these arguments in two ways. One is that using the internet has never been free. From ARPANET, known as the beginning of the U.S. Internet, to the commercialization of backbone, no Internet has been considered or implemented for free since the early Internet network was devised. Also, the U.S government was paying subsidies or institutions were paying fees to secure network operations for the NSFNET backbone. the other is that "free peering" refers to barter transactions between ISPs, not to free access to counterpart internet networks. Second, this study analyze the FCC' executive order of conditioned merger approval and the court's related ruling and verify that using the internet is not free. According to the analysis, this study finds that it's real situation to make paid settlements between ISP-CPs (including OTTs) in the US Internet market at the moment. This study concludes that the Internet has never been free in terms of its technical characteristics, network structure, network operation, and system. Also it proposes how to improve the domestic settlement system between ISPs-CPs in terms of policy and regulation.

• Journal of Korea Multimedia Society
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• v.6 no.3
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• pp.496-507
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• 2003

Rapidly increasing Internet traffic demands require IP protocol based on high quality networking technology. Accordingy, our Internet has evolved from best-effort service toward differentiated service framework so as to implement QoS as prerequisite to a series of new applications. In addition, it is forecasted that existing transport network will be reorganized into DWDM-based optical Internet sooner or later under the influence of Internet demands for higher bandwidth based on QoS. This study shows a way to an effective implementation in some aspects: QoS implementation on DWDM-based optical Internet network, control protocol, backbone network architecture and switching technology for the Next Generation Internet (NGI).

• Journal of Applied Reliability
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• v.1 no.2
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• pp.121-138
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• 2001

Due to large demand for high speed and great capacity for data transfer, WDM, which uses the wavelength division multiplexing technique, is known as alternative way to satisfy those demand for its flexible network operation and management, easy network expansion with existing networks, and enhancement of efficient data transfer rate. For these reasons, a new high capacity WDM optical communication network plan was established. Therefore, the quality of currently deployed optical cables with 81.6 km in length should be assessed to ensure if high capacity WDM system could be implemented on existing optical cables. Two important characteristic parameters, Transfer Loss and PMD (Polarization Mode Dispersion), were measured to evaluate quality of existing optical cable. Transfer Loss was measured at 0.244 dB per kilometer, which is lower than the design standard value at 0.275 dB/km. The measured PMD value gave at 0.030ps/km, and it, therefore, satisfies the value recommended by ITU-T (International Telecommunication Union-T) of 0.5ps/km. In addition, the transfer characteristic for existing 2.5 Gbps and 10 Gbps system were measured and evaluated, and the results showed that error-free transfer is very much feasible. Computer simulation for DWDM system, which is likely be a future backbone network in Korea, to assess the transfer characteristic using the same condition employed for 2.5 Gbps and 10 Gbps was carried out as well. The simulation verified that a stable network operation and reliable service could be provided.

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.501-508
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• 2011

In this paper, we propose a channel allocation algorithm of MSAP(Mobile Subscriber Access Point) and data delivery scheme exploiting the symbol level network coding. The network is comprised of TS(Tactical Switch) as a backbone node, MSAPs, and TMFTs(Tactical Multi-Function Terminal). The TS performs the channel allocation considering the communication range overlapping between the neighboring MSAPs and applies the symbol level network coding, if necessary, depending on the position of the TMFTs. Assuming the number of available antennas of TMFT and MSAP will be extended to two from one, we propose two schemes: single mode and dual mode. Through the simulation, we show that the proposed delivery scheme provides higher delivery ratio and lower delivery delay compared with the legacy store-and-forward scheme.

• Journal of Communications and Networks
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• v.17 no.6
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• pp.558-567
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• 2015

In recent years, we have seen a proliferation of mobile-network-enabled smart objects, such as smart-phones and smart-watches, that form a cyber-physical integrated network to connect the cyber and physical worlds through the capabilities of sensing, communicating, and computing. Discovery of the relationship between smart objects is a critical and nontrivial task in cyber-physical integrated network applications. Aiming to find the most stable relationship in the heterogeneous and dynamic cyber-physical network, we propose a distributed and efficient relationship-discovery algorithm, called dynamically maximizing remaining unchanged time with minimum connected dominant set (DMRUT-MCDS) for constructing a backbone with the smallest scale infrastructure. In our proposed algorithm, the impact of the duration of the relationship is considered in order to balance the size and sustain time of the infrastructure. The performance of our algorithm is studied through extensive simulations and the results show that DMRUT-MCDS performs well in different distribution networks.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.1-5
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• 2007

Wavelength-division multiplexed (WDM) networks are emerging to be the right choice for the future transport networks. In WDM networks, the optical layer provides circuit-switched lightpath services to the client layer such as IP, SONET and ATM. The set of lightpaths in the optical layer defines the virtual topology. Since the optical switches are reconfigurable, the virtual topology can be reconfigured in accordance with the changing traffic demand pattern at theclient layer in order to optimize the network performance. We present a new approach to the virtual topology reconfiguration and loadbalancing problem for wavelength-routed, optical wide-area networks under dynamic traffic demand. By utilizing the measured Internet backbone traffic characteristics, our approach follows the changes in traffic without assuming that the future traffic pattern is known. For the simulation traffic modeling, we collected the data from real backbone traffic. Experiments show that the standard deviation compared to previous technique is reduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.3A
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• pp.287-295
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• 2010

In wireless sensor networks(WSNs), the studies that support sink mobility without global position information exploit a Backbone-based Virtual Infrastructure (BVI) which considers one-hop clusters and a backbone-based tree. Since the clusters of a sink and a source node are connected via flooding into the infrastructure, it causes high routing cost. Although the network could reduce the number of clusters via multi-level clusters, if the source nodes exist at nearest clusters from the cluster attached by the sink and they are in different branches of the tree, the data should be delivered via detour paths on the tree. Therefore, to reduce the number of clusters, we propose a novel multi-hop cluster based communication protocol supporting sink mobility without global position information. We exploit a rendezvous cluster head for sink location service and data dissemination but the proposed protocol effectively reduces data detour via comparing cluster hops from the source. Simulation shows that the proposed protocol is superior to the existing protocols in terms of the data delivery hop counts.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.11A
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• pp.1101-1112
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• 2006

With the recent growth in demand for high-data rate multimedia services in the wireless environments, the Mobile Broadband Wireless Access (MBWA) technologies, such as WiBro (Wireless Broadband internet) system, are gradually coming into the spotlight. Unlike the conventional mobile communication networks based on cellular system, the WiBro system basically consists of IP based backbone networks that will be ultimately deployed by Ipv6 (IP version six) based backbone networks according to the All-IP trend for the network evolution. In such wireless mobile environments, it is needed to support the mobility management protocol on network layer as well as physical layer and Medium Access Control (MAC) layer in WiBro system. Accordingly, in this paper, we propose a fast handover scheme for improving the handover performance in IPv6 based WiBro system and show that the proposed scheme achieves loss-free and low handover latency during inter-subnet movement of the mobile stations through the simulation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.4
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• pp.511-523
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• 2023

Research on the integration of unmanned aerial vehicles and deep learning for reinforced concrete damage detection is actively underway. Convolutional neural networks have a high impact on the performance of image classification, detection, and segmentation as backbones. The MobileNet, a pre-trained convolutional neural network, is efficient as a backbone for an unmanned aerial vehicle-based damage detection model because it can achieve sufficient accuracy with low computational complexity. Analyzing vanilla convolutional neural networks and MobileNet under various conditions, MobileNet was evaluated to have a verification accuracy 6.0~9.0% higher than vanilla convolutional neural networks with 15.9~22.9% lower computational complexity. MobileNetV2, MobileNetV3Large and MobileNetV3Small showed almost identical maximum verification accuracy, and the optimal conditions for MobileNet's reinforced concrete damage image feature extraction were analyzed to be the optimizer RMSprop, no dropout, and average pooling. The maximum validation accuracy of 75.49% for 7 types of damage detection based on MobilenetV2 derived in this study can be improved by image accumulation and continuous learning.