• Journal of information and communication convergence engineering
• /
• v.2 no.1
• /
• pp.15-21
• /
• 2004

One of the most important issues in designing a network and realizing a service is dealing with traffic characteristics. Recent experimental research on LAN, WAN, and VBR traffic properties has highlighted that real traffic specificities can not be displayed because the current models based on the Poisson assumption under estimate the long range dependency of network traffic and self-similar peculiarities. Therefore, a new approach using self-similarity characteristics as a real traffic model was recently developed. In This paper we discusses the definition of self-similarity traffic. Moreover, real traffic was collected and we generated self-similar data traffic like real traffic to background load. On the existing ABR congestion control algorithm transmission throughput with the representative ERICA, EPRCA and NIST switch algorithm show the efficient reaction about the burst traffic.

• Journal of KIISE:Information Networking
• /
• v.29 no.5
• /
• pp.553-561
• /
• 2002

We present a novel service discipline, called linear service discipline, to serve multiple QoS queues sharing a resource and analyze its properties. The linear server makes the output traffic and the queueing dynamics of individual queues as a linear function of its input traffic. In particular, if input traffic is Gaussian, the distributions of queue length and output traffic are also Gaussian with their mean and variance being a function of input mean and input power spectrum (equivalently, autocorrelation function of input). Important QoS measures including buffer overflow probability and queueing delay distribution are also expressed as a function of input mean and input power spectrum. This study explores a new direction for network-wide traffic management based on linear system theories by letting us view the queueing process at each node as a linear filter.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.4
• /
• pp.895-909
• /
• 2013

Distributed Denial-of-Service (DDoS) attacks towards name servers of the Domain Name System (DNS) have threaten to disrupt this critical service. This paper studies the vulnerability of the cache server to the flooding DNS query traffic. As the resolution service provided by cache server, the incoming DNS requests, even the massive attacking traffic, are maintained in the waiting queue. The sojourn of requests lasts until the corresponding responses are returned from the authoritative server or time out. The victim cache server is thus overloaded by the pounding traffic and thereafter goes down. The impact of such attacks is analyzed via the model of queuing process in both cache server and authoritative server. Some specific limits hold for this practical dual queuing process, such as the limited sojourn time in the queue of cache server and the independence of the two queuing processes. The analytical results are presented to evaluate the impact of DDoS attacks on cache server. Finally, numerical results are provided for further analysis.

• Journal of the Society of Naval Architects of Korea
• /
• v.60 no.6
• /
• pp.473-481
• /
• 2023

In this study, a simulation system was developed to verify autonomous navigation algorithm in complex maritime traffic areas. In particular, real-world maritime traffic scenario was applied by considering near real-time maritime traffic information provided by Korean e-Navigation service. For this, a navigation simulation system of Unmanned Surface Vehicle (USV) was integrated with an e-Navigation equipment, called Electronic Chart System (ECS). To verify autonomous navigation algorithm in the simulation system, initial conditions including initial position of an own ship and a set of paths for the ship to follow are assigned by an operator. Then, considering real-world maritime traffic information obtained from the service, the simulation is implemented in which the ship repeatedly travels by avoiding surrounding obstacles (e.g., approaching ships). In this paper, the developed simulation system and its application on verification of the autonomous navigation algorithm in complex maritime traffic areas are introduced.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.21 no.1
• /
• pp.103-118
• /
• 1996

With the advent of B-ISDN based on ATM technonlogy, ther are increasing needs for the interconnection of existing LAN/MAN's through ATM networks. ATM networks, therefore, must provide connectionless service. In this paper, the traffic distributio scheme using multi-path is proposed to support efficient connectionless service in ATM networks. Because the proposed scheme distributed the bursty traffic arrived in the interworking unit (IWU) and the connectionless server (CLS) from LAN-terminals, it alleviates the packet loss ratio caused by buffer overflow at IWU/CLS and is able to use nettowrk resources efficiently according to the network conditions and the amount of the traffic arrived at IWU/CLS. This paper presents the distribution algorithm and the IWU/CLS, CLS-CLS closed-loop rate control scheme.

• Journal of Navigation and Port Research
• /
• v.46 no.5
• /
• pp.392-399
• /
• 2022

With digitalization accelerated by the 4th industrial revolution, the marine traffic environment is also expected to change rapidly. The purpose of this study was to derive a new service for Aids to Navigation (AtoN) to respond to a new marine traffic environment and suggest service requirements from the perspective of the ship's operator. For this purpose, a survey of ship operators was conducted and IPA analysis was performed. Marine traffic intelligence and information services and Image-based ocean environment information services were deduced as high-priority services from the perspective of ship operators. Thus, the derived results can serve as basic data for developing new AtoN services and determining policy directions.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.26 no.4
• /
• pp.415-421
• /
• 2008

The purpose of this study is to provide a sensor based service model for traffic facilities in u-City through analysing the present condition of urban infrastructure, especially traffic facilities management. In order to achieve this purpose, we did a comparative analysis of internal and external situation of ITS(Intelligent Transport System) and classified service for traffic facilities to 3 categories, namely traffic flow management, traffic information offering, formation of road structure. Also, we examined technological trend of USN(Ubiquitous Sensor Network). Through this process, we present a sensor based service model of traffic facilities for building sustainable road environment.

• Proceedings of the KOR-KST Conference
• /
• 2007.05a
• /
• pp.399-408
• /
• 2007

Dedicated Short Range Communications(DSRC) is a block of spectrum in the 5.8GHz band. DSRC is the useful technology of ITS Service. Japan operates ETCS, VICS by DSRC technology and DSRC technology is used ETCS Standard in Korea. There are many kind of utilization of DSRC in ITS. This is a study for traffic information service and collection with DSRC. Traffic management server service traffic information to driving vehicle by RSE(Road Side Equipment). OBU(Onboard Unit) in vehicle send the information to PDA(Personal Digital Assistant). Client S/W show the information to driver by text, pictogram, sound and return PDA H/W ID to OBU. Server make section traffic information by the PDA H/W ID information.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.7 no.1
• /
• pp.38-55
• /
• 2013

Wireless network systems provide fast data transmission rates and various services to users of mobile devices such as smartphones and smart pads. Because many people use high-performance mobile devices, the use of real-time multimedia services is increasing rapidly. However, the preoccupation of resources by real-time traffic users is causing harm to other services-for example, frequent call interference, lowered service quality, and poor network performance. This paper suggests a resource allocation algorithm for effective traffic service support in a hybrid network. The main objective is to obtain an optimum value of data rates by comparing user requirements with the amount of resources that can be allocated. A new mechanism based on Adaptive-Quality of Service (QoS) and a monitoring system based on Queue-Aware are proposed. Adaptive-QoS supports effective resource control according to the type of traffic service, and the monitoring system based on Queue-Aware measures the amount of resources in order to calculate the maximum that can be allocated. We apply our algorithm to a test system and use Qualnet 4.5.1 to evaluate its performance.

• ETRI Journal
• /
• v.24 no.1
• /
• pp.43-55
• /
• 2002

This paper proposes a flow-based admission control algorithm through an Asynchronous Transfer Mode (ATM) based Multi-Protocol Label Switching (MPLS) network for multiple service class environments of Integrated Service (IntServ) and Differentiated Service (DiffServ). We propose the Integrated Packet Scheduler to accommodate IntServ and Best Effort traffic through the DiffServ-aware MPLS core network. The numerical results of the proposed algorithm achieve reliable delay-bounded Quality of Service (QoS) performance and reduce the blocking probability of high priority service in the DiffServ model. We show the performance behaviors of IntServ traffic negotiated by end users when their packets are delivered through the DiffServ-aware MPLS core network. We also show that ATM shortcut connections are well tuned with guaranteed QoS service. We validate the proposed method by numerical analysis of its performance in such areas as throughput, end-to-end delay and path utilization.