• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.406-408
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• 2001

이 논문에서는 TCP의 최근 버전인 TCP Reno 버전의 동작을 모델링 하는 방법을 통하여 살펴본다. 이 논문에서 사용한 방법은 하나의 소스를 마코비안 모델을 사용하여 ON-OFF 형태로 구성하며 이 방법을 통하여 빠르고 정확한 TCP 성능 측정 도구를 구성하고자 한다. 결과적으로 이러한 접근은 네트워크 성능과 관련된 출력률, 지연, 패킷 손실률 등을 측정할 수 있다. 또한 이렇게 얻어진 결과는 동일한 트래픽 설정을 사용한 시뮬레이션을 통하여 유효성을 증명하여 본다.

• The Journal of the Korea Contents Association
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• v.10 no.8
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• pp.73-83
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• 2010

This paper investigates protocol architecture of a Web-ZigBee gateway for interconnecting TCP/IP-based networks and ZigBee/IEEE802.15.4-based wireless sensor networks. The Web-ZigBee gateway delivers data between the TCP/IP network and the ZigBee network. Since those two networks have different communication protocols, a protocol translation mechanism is needed. Herein, we propose a method to deliver query messages from the Internet to the sensor network and receive data from sensors. The protocol translation is performed in the translation layer that is placed above the two application layers, i.e., the Internet application layer and ZigBee application layer. Among various interfaces, we use CGI programming to take care of translation functions efficiently. The CGI manages query information from a client on the Internet and data from the ZigBee sensor network. Whereas the TCP/IP enabled sensor network overlays two heterogeneous communication protocols, overlaying layers increase the complexity and cost of implementing the sensor network. On the contrary, the sensors in our gateway-based system are not only light (because each communication protocol works independently without overlaying), but also efficient because the translation layer mostly alleviates header overloading.

• Journal of Korea Multimedia Society
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• v.12 no.11
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• pp.1521-1529
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• 2009

There is a serious unfairness problem between upstream and downstream flows of AP in IEEE 802.11 Wireless LAN. This problem is because Wireless LAN's DCF MAC protocol provides AP with equal channel access priority to mobile noded. Also, it makes this problem worse that the TCP's Data segment loss is more effective on throughput than the TCP's ACK segment. In this paper, we first make several simulations to analysis the unfairness in the various point of view and to find reasons of the unfairness. Also, this paper presents AP's scheduling scheme to alleviate the unfairness problem and evaluate the scheme through ns2 simulator.

• Journal of Korea Multimedia Society
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• v.12 no.5
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• pp.617-632
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• 2009

In this paper we propose a technique of implementing the reconfigurable network protocol stack that allows for partitioning network protocol functions into software and hardware tasks on a SoC (System on Chip) platform. Additionally, we present a method that guarantees the deadline of both an individual task and messages exchanging among tasks in order to meet the deadline of real-time multimedia and networking services. The proposed real-time message exchange method guarantees the deadline of messages generated by multimedia services that are required to meet the real-time properties of multimedia applications. After implementing the networking functions of TCP/IP protocol suite into hardware and software tasks, we verify and validate their performance on the SoC platform. Experimental results indicate that the proposed technique improves the performance of TCP/IP protocol suit as well as application service satisfaction in application-specific real-time.

• Journal of the Korea Society of Computer and Information
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• v.9 no.2
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• pp.7-17
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• 2004

It requires that user have to verify and conform with user authentication Protocol on non-meet face to face internet services offered by mobile terminal which user make known user's own intention, and user be using the normal. It is more operation time authentication protocol than Access control Protocol. That is what need to be user authentication protocol have verified security. non-reputation, and improved high-performance in operation time for mobile terminal. In order to solve the above demand, in this paper, we would design for mobile terminal of TCP User Authentication ECC Algorithm Protocol with a performance test. Algorithm has 160 bit key and designed IPv4 & IPv6 frame architecture. We should conclude that the proposed protocol have more verified security, non-reputation, confidentiality, and improved high-performance in operation time of mobile terminal from 1 to 17 times than before.

• Journal of KIISE
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• v.45 no.1
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• pp.76-85
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• 2018

Governments and public agencies try to use the cloud to carry out their work and provide public services. However, a public cloud is vulnerable to security side because it has a structure to support services using public networks (i.e, the internet). Thus, this paper finds the general security vulnerabilities of a network and compares and analyzes the characteristics of transport protocols (UDP, TCP, SCTP, and MPTCP) on the basis of their security vulnerabilities. This paper uses a reliability and security factor for the comparative analysis, evaluates the security exposure, and chooses a suitable protocol considering the security of the transport protocols in the cloud circumstance.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.509-516
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• 2018

TCP is a well-known communication protocol which is widely used for reliable message transmissions. The urgent mechanism of TCP plays a key role to transmit messages with a high priority. If a high priority message occurs at the transmitting node, the urgent mechanism informs the receiving node about the presence of a high priority message prior to its transmission so that the receiving node can be prepared for handling this message in advance. This implies that the existing urgent mechanism of TCP does not guarantee an immediate or faster delivery of the high priority message itself. Therefore, the ability of priority-based transmission is required on TCP not only to ensure reliable transmissions of normal messages but also to offer a differentiated service according to the priority of message. This paper presents a priority-based transmission algorithm over TCP using a priority queue in a multi-threaded environment. The effectiveness of the proposed algorithm is explored using an experimental setup in which various messages with different priority levels are transmitted.

• The KIPS Transactions:PartC
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• v.11C no.2
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• pp.245-252
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• 2004

Stream Control Transmission Protocol(SCTP) is a new connection-oriented, reliable delivery transport protocol operating on top of an unreliable connectionless packet service such as IP. It inherits many of the functions developed for TCP, including flow control and packet loss recovery functions. In addition, it also supports transport layer multihoming and multistreaming In this paper, we study the impact of multi-homing on the performance of SCTP. We first compare performance of single-homed SCTP. multi-homed SCTP, TCP Reno and TCP SACK. We, then describe potential flaw in the current SCTP retransmission policy, when SCTP host is multihomed. Our Results show that SCTP performs better than TCP Reno and TCP SACK due to several changes from TCP in its congestion control mechanism. In particular. multi-homed SCTP shows the best result among the compared schemes. Through experimentation for multi-homed SCTP, we found that the current SCTP retransmission policy nay deteriorate the perfomance when the retransmission path it worse than the original path. Therefore, the condition of retransmission path is a very important factor In SCTP performance and a proper mechanism would be required to measure the condition of the retransmission path.

• 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.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.363-373
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• 2010

The existing QoS mechanisms for video streaming are short of the consideration for various user environments and the characteristic of streaming applying programs. In order to overwhelm this problem, studies on the video streaming protocols exploiting scalable video coding (SVC), which provide spatial, temporal, and qualitative scalability in video coding, are progressing actively. However, these protocols also have the problem to deepen network congestion situation, and to lower fairness between other traffics, as they are not equipped with congestion control mechanisms. SVC based streaming protocols also have the problem to overlook the property of videos encoded in SVC, as the protocols transmit the streaming simply by extracting the bitstream which has the maximum bit rate within available bandwidth of a network. To solve these problems, this study suggests TCP-friendly network adaptive SVC streaming(T-NASS) protocol which considers both network status and SVC bitstream property. T-NASS protocol extracts the optimal SVC bitstream by calculating TCP-friendly transmission rate, and by perceiving the network status on the basis of packet loss rate and explicit congestion notification(ECN). Through the performance estimation using an ns-2 network simulator, this study identified T-NASS protocol extracts the optimal bitstream as it uses TCP-friendly transmission property and perceives the network status, and also identified the video image quality transmitted through T-NASS protocol is improved.