• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1997.06a
• /
• pp.43-48
• /
• 1997

The video transmission for real-time viewing over the Internet is a core operation for the multimedia services. However, its realization is very difficult because the Internet has two major problems, namely, very narrow endpoint-bandwidth and the network jitter. We already proposed a scalable video transmission method in [8] which used MPEG-4 video VM(Verification Model) 2.0[3] for very low bit rate coding and an adaptive temporal rate control of video objects to overcome the network jitter problem. In this paper, we present the improved adaptive temporal rate control scheme for the scalable transmission. Experimental results for three test video sequences show that the adaptive temporal rate control can transfer the video bitstream at source frame rate under variable network condition.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.9 no.1
• /
• pp.45-57
• /
• 2005

In this paper, we extend the performance of bidirectional TCP connection over end-to-end network that uses transfer rate-based flow and congestion control. The sharing of a common buffer by TCP packets and acknowledgement has been known to result in an effect called ack compression, where acks of a connection arrive at the source bunched together, resulting in unfairness and degraded throughput. The degradation in throughput due to bidirectional traffic can be significant. Even in the simple case of symmetrical connections with adequate window size, the connection efficiency is improved about 20% for three levels of background traffic 2.5Mbps, 5.0Mbps and 7.5Mbps. Otherwise, the throughput of jitter is reduced about 50% because round trip delay time is smaller between source node and destination node. Also, we show that throughput curve is improved with connection rate algorithm which is proposed for TCP congetion avoidance as a function of aggressiveness threshold for three levels of background traffic 2.5Mbps, 5Mbps and 7.5Mbps. By analyzing the periodic bursty behavior of the source IP queue, we derive estimated for the maximum queue size and arrive at a simple predictor for the degraded throughput, applicable for relatively general situations.

• Journal of Korea Multimedia Society
• /
• v.5 no.3
• /
• pp.249-254
• /
• 2002

We consider a buffer-constrained adaptive quantization algorithm for image compression. Buffer control algorithm was considered with source coding scheme by some researchers and recently a formal description of the algorithm in terms of rate-distortion has been developed. We propose a buffer control algorithm that incorporates the buffer occupancy into the Lagrange multiplier form in a rate-distortion cost measure. Although the proposed algorithm provides the suboptimal performance as opposed to the optimal Vieterbi algorithm, it can be implemented with very low computaional complexity. In addition stability of this buffer control algorithm has been mentioned briefly using Liapnov stability theory.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.22 no.2
• /
• pp.259-267
• /
• 1997

The advent of B-ISDN using ATM(asynchronous transfer mode) made possible a variety of new multimedia services, however it also created a problem of congestion control due to bursty nature of various traffic sources. To tackle this problem, UPC/NPC(user parameter control/network parameter control) have been actively studied and DRLB(dynamic rate leaky bucket) algorithm, in which the token generation rate is changed according to states of data source andbuffer occupancy, is a good example of the UPC/NPC. However, the DRLB algorithm has drawbacks of low efficiency and difficult real-time implementation for bursty traffic sources because the determination of token generation rate in the algorithm is based on the present state of network. In this paper, we propose a more plastic and effective congestion control algorithm by combining the DRLB algorithm and neural network based prediction to remedy the drawbacks of the DRLB algorithm, and verify the efficacy of the proposed method by computer simulations.

• Proceedings of the SAREK Conference
• /
• 2009.06a
• /
• pp.77-82
• /
• 2009

If we can supply accurate minute flow rate to the households, we can solve many problems that are occurring in consequences of uncontrolled flow rate for the households. Therefore, this paper presents an innovative solution to the source of the problems by illustrating how we can control the flow rate to the household. This paper proves such problems even can be solved in a case when there is a room turned off the heating.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 1997.06a
• /
• pp.31-36
• /
• 1997

Bit allocation is a critical problem in video encoding such as MPEG. To improve the quality of the reconstructed sequence for a given bit rate, the assigned target bits for a group of pictures (GOP) must be allocated to each picture efficiently. In this paper, we derive a target bit allocation algorithm for more efficient rate control, by assuming that the average rate-distortion curve for an input source is logarithmic. This target bit allocation is based on Shannon's rate-distortion theory, which deals with the minimization of source distortion subject to a channel rate constraint. Simulation results show that the proposed target bit allocation algorithm provides better performance than the one in MPEG-2 Test Model 5 (TM5).

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.1371-1376
• /
• 2003

In the thermal power plant, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, Strictly maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature, the change of the dynamic characteristics in the reheater. Up to the present time, PID Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on tuning of the 2-DOF PID Controller on the DCS for steam temperature control using immune based multiobjective approach. The stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Therefore tuning technique of multiobjective based on immune network algorithms in this paper can be used effectively in tuning 2-DOF PID controllers.

• Journal of the Korea Society of Computer and Information
• /
• v.7 no.4
• /
• pp.188-198
• /
• 2002

In this paper, we propose an active network to support reliable data transmission in the mobile ad-hoc network. The active network uses DSR(Dynamic Source Routing) protocol as its basic routing protocol, and uses source and destination nodes as key active nodes. For reliable improvement the source node is changed to source active node to add function that its buffer to store the last data with the flow control for data transmission per destination node. The destination node is changed to destination active node to add function that it requests the re-transmission for data that was not previously received by the destination active node with the flow control for data reception per source active node As the result of evaluation. we found the proposed active network guaranteed reliable data transmission with almost 100% data reception rate for slowly moving mobile ad-hoc network and with more 95% data reception rate, which is improvement of 3.5737% reception rate compared with none active network, for continuously fast moving mobile ad-hoc network.

• Journal of the Korea Society of Computer and Information
• /
• v.4 no.4
• /
• pp.140-147
• /
• 1999

ABR uses the extra network resource more efficiently which uses not the guaranteed service in ATM and supports the best effort which the characteristics of application is bursty and maximum transfer rate is high. Switches for using ABR flow control differentiate EFCI switches (which supply only the congestion state information) from ER switches (which supply fair rate to source). This paper analyses the switches operation technique for efficiently managing ABR traffic in case which the network mixes EFCI switches and ER switches in ATM.

• Journal of KSNVE
• /
• v.8 no.3
• /
• pp.485-493
• /
• 1998

Many of the adaptive noise control systems utilize a form of the least mean square (LMS) algorithms. In the active control of noise, it is common practice to locate an error microphone far from the control source to avoid the near-field effects by evanescent waves. Such a distance between the control source and the error microphone makes a certain level of time-delay inevitable and, hence, may yield undesirable effects on the convergence properties of control algorithms such as filtered-x LMS. This paper discusses the dependence of the convergence rate on the acoustic error path in these popularalgorithms and introduces new algorithms which increase the convergence region regardless of the time-delay in the acoustic error path. Performances of the new LMS algorithms are presented in comparison with those by the conventional algorithms based on computer simulations and experiments.