• Proceedings of the Korean Information Science Society Conference
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• 2000.04a
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• pp.310-312
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• 2000

명시적인 자원 할당과 스케줄링에 의해 QoS를 제공 할 수 있는 방안으로 RSVP가 제안되었으나 내부 구조 변경이나 확장성의 문제를 내포하고 있다. 그래서 IETF에서는 차등 서비스(Differentiated Service)를 이용하여 서비스 영역을 확장하려는 연구가 활발히 진행중이다. DiffServ는 확장성을 고려하여 RSVP와 같은 개별 flow에 대한 QoS 제공이 아닌 flow들의 집합(aggregated)으로 차등적인 서비스를 제공하는 방법이다. 본 논문에서는 aggregated flow로 서비스를 제공할 때 불특정 flow에 대한 QoS 손실을 막기 위해 Token Bucket Meter 처리 전에 사전 모니터링에 의해 자원공유의 공정성과 처리 속도를 향상시킬 수 있는 TC(Traffic Conditioner)를 설계, 구현하여 다수 subnetwork에서의 flow가 자원을 공정하게 공유함을 결과로 보였다.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.652-653
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• 2015

This study investigates the effect of real-time traffic information on the traffic flows in Korea. Recently, the development of smartphones has made it easier to use the route guidance service based on real-time traffic information. By the Big Data analysis in the study, it was found that the number of postings on the web community sites increased sharply in 2010 and 2011 when the smartphones spread widely. In the analysis of the traffic speeds by time, the average traffic speeds for morning and evening rush hours on weekdays from 2009 to 2014 of the 142 sections in the 6 national highways in Gyeonggi-do, Korea were used. From the results of the analysis, it was found that the percentage of the number of sections with the improved traffic flows increased greatly in 2012 compared to 2011. The findings of the study indicate the effect of the real-time traffic information on improving traffic flows.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.5 no.9
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• pp.1492-1512
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• 2011

Due to multiple hops, mobility and time-varying channel, supporting delay sensitive real-time traffic in wireless local area network-based (WLAN) mesh networks is a challenging task. In particular for real-time traffic subject to medium access control (MAC) layer control overhead, such as preamble, carrier sense waiting time and the random backoff period, the performance of real-time flows will be degraded greatly. In order to support real-time traffic, an efficient adaptive packet scheduling (APS) scheme is proposed, which aims to improve the system performance by guaranteeing inter-class, intra-class service differentiation and adaptively adjusting the packet length. APS classifies incoming packets by the IEEE 802.11e access class and then queued into a suitable buffer queue. APS employs strict priority service discipline for resource allocation among different service classes to achieve inter-class fairness. By estimating the received signal to interference plus noise ratio (SINR) per bit and current link condition, APS is able to calculate the optimized packet length with bi-dimensional markov MAC model to improve system performance. To achieve the fairness of intra-class, APS also takes maximum tolerable packet delay, transmission requests, and average allocation transmission into consideration to allocate transmission opportunity to the corresponding traffic. Detailed simulation results and comparison with IEEE 802.11e enhanced distributed channel access (EDCA) scheme show that the proposed APS scheme is able to effectively provide inter-class and intra-class differentiate services and improve QoS for real-time traffic in terms of throughput, end-to-end delay, packet loss rate and fairness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.9A
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• pp.1285-1294
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• 1999

In this paper we consider the performance of TCP video traffic over ABR with Long-Range Dependent VBR traffic. As compressed coded video traffics are increasing rapidly over Internet, lots of studies are being done for transmitting those traffics efficiently using limited network resources. We consider here the transmitting video service over ABR service in ATM networks, especially satellite networks. CBR or VBR services are suggested in transmitting the video traffic in ATM Forum TM 4.0. But ABR service connection, which is considered as appropriate service for data traffic, can be established with a small amount of bandwidth, MCR (Minimum cell rate). Furthermore ABR service can control the source's transmitting rate using feedback mechanism. Using this feature ABR service can be used in some applications which can control their quality of services corresponding to network loads. Compressed video sources with MPEG-2 are used for Long-Range Dependent VBR traffic here. We model the compressed video source to resemble the MPEG-2 transport streams. These compressed video traffic streams are consisted of three different frames, I-frame, P-frame, and B-frame. So when a network are overloaded, we can control the quality of service using this traffic features. TCP Traffics over ABR need large buffers in ATM switch to satisfy their QoS with background VBR traffics, which have high deviations in bandwidth. Furthermore satellite ATM networks with large feedback delay need large buffers corresponding RTT delay. The performance comparisons among EFCI and ER switch (ERICA+) switches in the network circumstances described above were shown in this paper. We also considered the case with ON-OFF VBR traffics.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11B
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• pp.1007-1015
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• 2003

In this Paper, we propose a method of determining the price for the elastic traffic in the current or future Internet services. First, we investigate the behavior in the consumption of bandwidth of elastic traffic in IP network. Next, we propose a new method to relate the bandwidth usage with the pricing for the elastic traffic, which is based partially or fully on the usage rate of the network bandwidth. Next, we propose an optimal charging function for elastic traffic, which is applicable to any Internet services. Finally, we will illustrate the implication of the work via simple numerical experiments.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.565-567
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• 2002

DDOS공격은 최근 인터넷 환경에서 큰 위험요소로 부각되고 있다. 하지만, DDOS공격을 완벽하게 막아내는 것은 현재까지 알려진 방법으로는 거의 불가능하다. 그 이유는DDOS 공격이 Vulnerability Exploit을 이용한 공격방법이 아니라 Network Resource를 고갈시켜서 공격대상 호스트의 서비스를 차단하기 때문이다. 그래서, DDOS공격을 방어하기 위해서는 DDOS공격 트래픽에 대한 정확한 분석과 탐지가 선행되어야 한다. 본 논문을 통해서 여러 가지 DDOS공격 Traffic의 특징을 살펴보고, Web traffic과의 차이를 통해 DDOS traffic을 탐지하는 방법을 제안하고자 한다.

• Proceedings of the KAIS Fall Conference
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• 2003.11a
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• pp.236-242
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• 2003

ATM ABR service controls network traffic using feedback information on the network congestion situation in order to guarantee the demanded service qualities and the available cell rates. In this paper we apply the control method using queue length prediction to the formation of feedback information for more efficient ABR traffic control. If backward node receive the longer delayed feedback information on the impending congestion, the switch can be already congested from the uncontrolled arriving traffic and the fluctuation of queue length can be inefficiently high in the continuing time intervals. The feedback control method proposed in this paper predicts the queue length in the switch using the slope of queue length prediction function and queue length changes in time-series. The predicted congestion information is backward to the node. NLMS and neural network are used as the predictive control functions, and they are compared from performance on the queue length prediction. Simulation results show the efficiency of the proposed method compared to the feedback control method without the prediction. Therefore, we conclude that the efficient congestion and stability of the queue length controls are possible using the prediction scheme that can resolve the problems caused from the longer delays of the feedback information.

• The Transactions of the Korea Information Processing Society
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• v.3 no.7
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• pp.1880-1893
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• 1996

In this paper, we propose the fuzzy traffic control method in ABR service for the effective use of ATM link. This method, a modified version of EPRCA which is one of rate control methods in ABR service, controls the values of the transmission rates of source by using the fuzzy traffic inference based on switch buffer size and buffer variate rate. For this method, we developed a model and algorithm of the fuzzy traffic control method and a fuzzy traffic controller, after studying fuzzy and neural networks which applied to ATM traffic control and EPRCA. For the fuzzy traffic controller, we also designed a membership function, fuzzy control rules and a max-min inferencing method. We conducted a simulation and compared the link utilization of the fuzzy traffic control method with that of the EPRCA method. The results of the simulation indicated that, compared to EPRCA, the fuzzy traffic control method improves the link utilization by 2.3% in a normal distribution model and by 2.7% in the MMPP model of the source.

• Journal of Advanced Navigation Technology
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• v.20 no.2
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• pp.141-147
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• 2016

Stable and reliable air traffic service is required for users (aircraft pilot, air traffic controller, airlines and public) through enhancing capability related to airport operation and continuously improving air navigation system. ASMS (air navigation service provider (ANSP) safety maturity survey) is to determine the level of management and safety requirement such as organization, risk, policy, process, training and environment in Air traffic service field. We designed and developed the survey (26 study areas of management part and 23 study areas of safety part) considering global best practices (Eurocontrol and FAA) and customizing domestic circumstances with quantitative level assessment regarding management and safety issue of Air navigation system. The survey enables the performance of Air navigation system to enhance and prevents from occurring accident or incident. Therefore, we provides best information with users as well as high quality Air traffic service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.12
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• pp.1160-1167
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• 2012

Identifying traffic is an important issue for many networking applications including quality of service, firewall enforcement, and network security. Once we know the purpose of using the traffic in the firewall, we can allow or deny it and provide quality of service, and effective operation in terms of security. However, a number of applications encrypts traffics in order to enhance security or privacy. As a result, effective traffic monitoring is getting more difficult. In this paper, we analyse SSH encrypted traffic and identify differences among SSH tunneling, SFTP, and normal SSH traffics. By using EM clustering, we identify traffics and validate experiment results.