• Journal of Broadcast Engineering
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• v.10 no.3
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• pp.297-312
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• 2005

The multimedia traffic of continuous video and audio data via streaming service accounts for a significant and expanding portion of the Internet traffic. This streaming data delivery is mostly based on RTP with UDP. However, UDP does not support congestion control. For this reason, UDP causes the starvation of congestion controlled TCP traffic which reduces its bandwidth share during overload situation. In this paper, we propose a new TCP-friendly rate control scheme called 'TF-RTP(TCP-Friendly RTP)'. In the congested network state, the TF-RTP exactly estimates the competing TCP's throughput by using the modified parameters. Then, it controls the sending rate of the video streams. Therefore, the TF-RTP adjusts its sending rate to TCP-friendly and fair share with competing TCP traffics. Through the simulation, we prove that the TF-RTP correctly estimates the TCP's throughput and improves the TCP-friendliness and fairness.

• Journal of KIISE:Information Networking
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• v.29 no.4
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• pp.437-446
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• 2002

In order to reduce the increasing packet loss rates caused by an exponential increase in network traffic, the IETF (Internet Engineering Task Force) is considering the deployment of active queue management techniques such as RED (Random Early Detection). While active queue management in routers and gateways can potentially reduce packet loss rates in the Internet, this paper has demonstrated the inherent weakness of current techniques and shows that they are ineffective in preventing high loss rates. The inherent problem with these queue management algorithms is that they all use static parameter setting. So, in case where these parameters do not match the requirement of the network load, the performance of these algorithms can approach that of a traditional Drop-tail. In this paper, in order to solve this problem, a new active queue management algorithm called ARED (Active RED) is proposed. ARED computes the parameter based on our heuristic method. This algorithm can effectively reduce packet loss while maintaining high link utilizations.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11S
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• pp.3723-3731
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• 2000

Recently, the growth of applications and services over high-speed Internet increase, ATM networks as wide area back-bone has been a major solution. The conventional TCP suite is still the standard protocol used to support upper application on current Internet and uses a window based protocol for flow control in the transport layer. When TCP data uses the UBR service in ATM layer, the control method is also buffer management. If a cell is discarded in ATM layer. one whole packet of TCP will be lost. Which is responsible for most TCP performance degradation and do not offer sufficiently QoS. To solve this problem, Several dropping strategies, such as Tail Drop, EPD, PPO, SPD, FBA, have been proposed to improve the TCP performance over ATM. In this paper, to improve the TCP fairness of end to end, we propose a packet dropping scheme algorithm using two fixed threshold. Under similar condition, we compared our proposed scheme with other dropping strategies. Although the number of VC is increased, simulation results showed that the proposed scheme can allocate more fairly each VC than other schemes.

• Convergence Security Journal
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• v.20 no.5
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• pp.3-10
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• 2020

Recently, the Internet and networks are regarded as essential infrastructures that constitute society, and security threats have been constantly increased. However, the network switch that actually transmits packets in the network can cope with security threats only through firewall or network access control based on fixed rules, so the effective defense for the security threats is extremely limited in the network itself and not actively responding as well. In this paper, we propose an in-network security framework using the high-level data plane programming language, P4 (Programming Protocol-independent Packet Processor), to deal with DDoS attacks and IP spoofing attacks at the network level by monitoring all flows in the network in real time and processing specific security attack packets at the P4 switch. In addition, by allowing the P4 switch to apply the network user's or administrator's policy through the SDN (Software-Defined Network) controller, various security requirements in the network application environment can be reflected.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.316-318
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• 2005

무선 ad-hoc 네트워크는 중앙 집중화된 관리 시스템이나 지원 서비스 없이 동적으로 임시 네트워크를 구성하는 이동 호스트(MH)들의 집합이다. 이러한 네트워크는 백본 호스트나 다른 MH로의 연결을 제공하기 위한 고정된 제어장치를 갖지 않으며, 각 MH가 라우터로 동작하며 전달받은 패킷을 다른 MH로 전달한다. 이러한 무선 ad-hoc 네트워크에서 단순히 최선의 서비스만을 제공하던 기존의 방법과 달리, 많은 사용자가 요구하는 QoS 서비스를 지원하기 위하여 기존 네트워크를 효율적으로 최대 활용하는 방안에 대한 연구가 활발히 진행되고 있다. 본 논문에서는 무선 ad-hoc 네트워크 내에서 QoS 서비스를 제공하기 위한 기법으로 각각의 이동 호스트들은 QoS DAG 그래프를 유지하며 이러한 그래프를 바탕으로 만들어진 QoS 정보 패킷을 이웃 이동 호스트들에게 지역 브로드캐스트 함으로써 전역적인 QoS 정보의 검색과 운용없이, 유용한 QoS 정보를 전역적으로 각 이동 호스트가 유지할 수 있고 이를 바탕으로 효율적인 QoS 라우팅이 수행되어지는 기법이다.

• Convergence Security Journal
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• v.6 no.1
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• pp.33-43
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• 2006

RFID System has an advantage that it need not touch an objects for identification of many objects. Because it is working through wireless communication. Also, So many objects can be identified with RFID System at once. However, although RFID System has convenience like above, it has serious privacy concern at the same time. If RFID System is working with an target object through wireless communication, other objects will respond to RFID System signal as well as a target object. Hence, RFID System can be easily exposed user privacy by attacker. In this paper, We propose RFID system authentication model in order to protecting user privacy and traking. Proposed RFID system is operating that not only server authenticate RFID reader but also RFID reader and tag authenticate mutually by using symetric cryptography that operating with tiny and simple processing.

• Convergence Security Journal
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• v.6 no.1
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• pp.55-63
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• 2006

In this paper, an algorithm that provisions absolute differentiation of packet delays is proposed with an objective for enhancing quality of service (QoS) in future packet networks. It features an adaptive scheme that compensates the deviation for prediction on the traffic to be arrived continuously. It predicts the traffic to be arrived at the beginning of a time slot and measures the actual arrived traffic at the end of the time slot, and derives the deviation between the two quantity. The deviation is utilized to the delay control operation for the next time slot to offset it. As it compensates the prediction error continuously, it shows superior adaptability to the bursty traffic as well as the constant rate traffic. It is demonstrated through simulation that the algorithm meets the quantitative delay bounds and shows superiority to the traffic fluctuation in comparison with the conventional mechanism.

• Journal of Internet Computing and Services
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• v.5 no.5
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• pp.39-48
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• 2004

For transporting real-time multimedia traffic, RTP is considered as one of the most promising protocols operating at application layer. In order to manage and control the real-time multimedia traffic within networks, network managers need to monitor and analyze the traffic delivering through their networks. However, conventional traffic analyzing tools can not exactly classify and analyze the real-time multimedia traffic using RTP on the basis of real-time as well as non-real-time operations. In this paper, we propose an efficient online classification method of RTP packets, which can be used on high-speed network links. The accuracy and efficiency of the proposed methodhave been tested using captured data from a KIX node with 100 Mbps links, which interconnects between domestic and overseas Internet networks and is operated by NCA.

• Proceedings of the Korean Information Science Society Conference
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• 2007.06d
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• pp.477-482
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• 2007

최근 다양한 P2P 프로그램을 많이 사용함에 따라 네트워크에서 생겨나는 트래픽의 상당 부분이 P2P가 발생시키는 트래픽으로 이미 HTTP, FTP의 양을 훨씬 뛰어넘고 있다. 현재 인터넷 환경에서 방화벽을 통과하기 위해 포트번호를 변경하여 통신을 하는 새로운 P2P응용들의 행동들은 전통적인 well-known port 기반의 응용프로그램을 구분하는 단순한 분석 방법만으로 신뢰하기가 어렵다. 새로운 P2P 응용들과 같은 트래픽 모니터링의 정확도를 높이기 위해서는 TCP/IP 헤더만이 아니라 패킷이 담고 있는 페이로드 내용에 대한 조사 차원의 모니터링 방법이 필요하다. 본 논문에서는 TCP/IP 헤더 정보와 더불어 패킷의 페이로드 내용을 조사하여 P2P 트래픽을 탐지하는 모니터링 기법을 제안한다. 이어 탐지되는 P2P 트래픽에 대하여 Linux Netfilter Framework의 Queuing Discipline에서 제공하는 계층적인 우선순위 큐를 사용하여 일정한 양의 대역폭을 할당하는 정책을 적용함으로써 안정적이면서 효율적인 네트워크 운용 방안을 제시한다.

• The Journal of the Korea Contents Association
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• v.8 no.1
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• pp.169-176
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• 2008

In this paper, we develop radio resource management queueing model in IEEE 802.IS networks considering both connection and packet level. In the upper level connection, we model connection admission control depending on availability of bandwidth and priority queue in each service class. In the lower level packet, we model dynamic bandwidth allocation considering threshold and availability of bandwidth in each service class simultaneously. Hierarchical model is built using an extended Petri Nets, SRN (Stochastic Reward Nets). Bandwidth utilization and normal throughput as performance index for all service classes of traffic are calculated and numerical results are obtained.