• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.4
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• pp.1442-1462
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• 2014

Packet classification is a key technology of the Internet for routers to classify the arriving packets into different flows according to the predefined rulesets. Previous packet classification algorithms have mainly focused on search speed and memory usage, while overlooking update performance. In this paper, we propose PreCuts, which can drastically improve the update speed. According to the characteristics of IP field, we implement three heuristics to build a 3-layer decision tree. In the first layer, we group the rules with the same highest byte of source and destination IP addresses. For the second layer, we cluster the rules which share the same IP prefix length. Finally, we use the heuristic of information entropy-based bit partition to choose some specific bits of IP prefix to split the ruleset into subsets. The heuristics of PreCuts will not introduce rule duplication and incremental update will not reduce the time and space performance. Using ClassBench, it is shown that compared with BRPS and EffiCuts, the proposed algorithm not only improves the time and space performance, but also greatly increases the update speed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.1
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• pp.147-153
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• 2015

Since the DoS(Denial of Service) attack is still an important vulnerable element in many web service sites, sites including public institution should try their best in constructing defensive systems. Recently, DDoS(Distributed Denial of Service) has been raised by prompting mass network traffic that uses NTP's monlist function or DoS attack has been made related to the DNS infrastructure which is impossible for direct defense. For instance, in June 2013, there has been an outbreak of an infringement accident where Computing and Information Agency was the target. There was a DNS application DoS attack which made the public institution's Information System impossible to run its normal services. Like this, since there is a high possibility in having an extensive damage due to the characteristics of DDoS in attacking unspecific information service and not being limited to a particular information system, efforts have to be made in order to minimize cyber threats. This thesis proposes a method for using TTL (Time To Live) value in IP header to detect DDoS attack with IP spoofing, which occurs when data is transmitted under the agreed regulation between the international and domestic information system.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.1 no.1
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• pp.51-64
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• 2002

This paper analyzes performance measures of a Bluetooth_based mobile home network system. The home network system consists of terminals with Bluetooth interfaces, access points (AP), a home PC, and a gateway A mobile host in wireless terminals uses Mobile IP for supporting the mobility This paper considers four types of data traffic, which are new connection traffic, handoff traffic, Internet data traffic, and control data traffic and suggests a queueing system model of the home network system, where the AP and the home PC are modeled as M/G/1 with four priority queues and the gateway is modeled as M/G/1 with a single queue The generation rate and service time of individual traffic influence their performance measures. Based ell the suggested model, we propose the elapsed time of data traffic in terms of the number of cells, the number of Home PCs, arrival rates of four types of traffic and the service rates of AP/Home PCs/Gateway To analyze influences on the elapsed time with respect to arrival rate of four types of traffic, some examples are given.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.163-168
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• 2000

This paper proposes the new concept & design method and implementation of LonWorks network system for remote monitoring & lighting dimming control and telemetry using Web network. The Experimental LonWorks network system for telemetry & remote monitoring and control are designed and fabricated. As a result, it is verified that LonWorks is open, interoperable, reliable network system from the experimental results, especially, it seamlessly links the data and control networks, allowing the IP(internet) network to be treated as an extension of the LonWorks networks, and vice versa.

• The Journal of the Korea institute of electronic communication sciences
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• v.3 no.3
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• pp.188-194
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• 2008

In this paper, we propose for improving QoS in Hospital wireless network using Cellular-IP/PRC(Paging Route Cache) with Paging Cache and Route Cache in Cellular-IP and propose for performance of realtime and non-real time handoff service using Handoff state machine Paging Route Cache. Although the Cellular-IP/PRC technology is devised for mobile internet communication, it has its vulnerability in frequent handoff environment. This handoff state machine using differentiated handoff improves quality of services in Cellular-IP/PRC Suggested algorithm shows better performance than existing technology in wireless mobile internet communication environment. When speech quality is secured considering increment of interference to receive in case of suppose that proposed acceptance method grooves base radio station capacity of transfer node is plenty, and moat of contiguity cell transfer node was accepted at groove base radio station with a blow, groove base radio station new trench lake acceptance method based on transmission of a message electric power estimate of transfer node be. Do it so that may apply composing PC(Paging Cache) and RC(Routing Cache) that was used to manage paging and router in radio Internet network in integral management and all nodes as one PRC(Paging Router Cache), and add hand off state machine in transfer node so that can manage hand off of transfer node and Roaming state efficiently, and studies so that achieve connection function at node. Analyze benevolent person who influence on telephone traffic in system environment and forecasts each link currency rank and imbalance degree, forecast most close and important lake interception probability and lake falling off probability, GoS(Grade of Service), efficiency of cell capacity in QoS because applies algorithm proposing based on algorithm use gun send-receive electric power that judge by looking downward link whether currency book was limited and accepts or intercept lake and handles and displays QoS performance improvement.

• Journal of Satellite, Information and Communications
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• v.2 no.2
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• pp.85-91
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• 2007

The satellite networks provide global coverage. The integration of terrestrial networks with a satellite network is the most attractive approach to develop a global communication system. The IP Multimedia Subsystem (IMS) is intended to be the system that will merge the internet with the telecom world. A user with a dual-mode terminal can access both the satellite network and terrestrial network. The seamless handoff between two networks and a user's QoS level is the major issue concerning this integration. In this paper, we propose IMS-based satellite/terrestrial integrated network architecture for a global communication system. Based on the proposed architecture, an inter-network handoff and end-to-end soft QoS procedure is discussed. Our proposed soft QoS scheme is also analyzed to calculate the number of rejected calls.

• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.101-107
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• 2007

In this paper, we have presented the results of Wavelength Division Multiplexing-Passive Optical Network (WDM-PON) based fiber-to-the-home (FTTH) field trial test which was held in the city of Gwangju. We have implemented an injection locked Fabry-Perot Laser Diode (FP-LD) based WDM-PON system and reliably delivered Internet Protocol TV (IP-TV), networked Personal Video Recorder (N-PVR), High-Definition Video on Demand (HD-VoD), Education on Demand (EoD) and Internet service as FTTH service through the system during the field trial test. We have also verified that the WDM-PON system worked well to provide quality of service (QoS) guaranteed 100Mbps bandwidth per subscriber. Furthermore, we have presented network designing issues in Outside Plant (OSP) and Customer Premises Network (CPN) that should be overcome to efficiently deploy FTTH service. Finally, based on the field trial test results, we proposed FTTH service deployment strategies.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.1A
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• pp.57-65
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• 2007

The overlay multicast that has been recently presented as IP alternative for the IP multicast has been getting much persuasion by the computing power of the hardware and the advancement of the network techniques to enforce Routing in application-level. In an overlay multicast, the system resource and the network bandwidth must be utilized efficiently to service real-time HDTV images. Specifically, the system must consider the delay and the jitter that can be incurred at the application-level. In this paper, we implement a server and a client to broadcast HDTV, in the session composed by the existing overlay multicast protocol. The broadcasting server performs the service using a TV tuner, An HDTV camcorder, and files, clients constituting a multicast group relay the received data to other clients. At this time, the information that the clients report periodically, including their delay and the network state, to the server is used as an important information to maintain an overlay session. The implementation is based on the DirectX and its performance is evaluated by the LAN test bed that has been set.

• Journal of Information Processing Systems
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• v.6 no.1
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• pp.1-20
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• 2010

Due to the convergence of voice, data, and video, today's telecom operators are facing the complexity of service and network management to offer differentiated value-added services that meet customer expectations. Without the operations support of well-developed Business Support System/Operations Support System (BSS/OSS), it is difficult to timely and effectively provide competitive services upon customer request. In this paper, a suite of NGOSS-based Telecom OSS (TOSS) is developed for the support of fulfillment and assurance operations of telecom services and IT services. Four OSS groups, TOSS-P (intelligent service provisioning), TOSS-N (integrated large-scale network management), TOSS-T (trouble handling and resolution), and TOSS-Q (end-to-end service quality management), are organized and integrated following the standard telecom operation processes (i.e., eTOM). We use IPTV and IP-VPN operation scenarios to show how these OSS groups co-work to support daily business operations with the benefits of cost reduction and revenue acceleration.

• Journal of Navigation and Port Research
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• v.44 no.2
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• pp.136-143
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• 2020

Maritime autonomous surface ships (MASS) has been developed over the years. But, there are many unresolved problems. To overcome these problems, this study proposes connected ship navigation system. The system comprises a slave ship and a master ship that leads the slave ship. To implement this system, communication network, route planning algorithms, and controllers are designed. The communication network is built using the transmission control protocol/Internet protocol (TCP/IP) socket communication method to exchange data between ships. The route planning algorithms calculate the course and distance of the slave ship using the middle latitude sailing method. Nomoto model is used as the mathematical model of the slave ship maneuvering motion. Then, the autoregressive with exogenous variables (ARX) model is used to estimate the parameters of Nomoto model. Based on the above model, the automatic steering controller is designed using a proportional-derivative (PD) control. Also, the speed controller is designed for the slave ship to maintain constant distance from the master ship. Sea experiments are conducted to verify the proposed system with two remodeled boats.