• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10B
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• pp.1971-1978
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• 1999

In this paper, we study the effects of long-range dependence (LRD) in VBR video traffic on queueing system. This paper consists of Part I and II. In Part I, we present a (LRD) video traffic model based on the shifting-level (SL) process. We observe that the ACF of an empirical video trace is accurately captured by the shifting-level process with compound correlation (SLCC): an exponential function in short range and a hyperbolic function in long range. We present an accurate parameter matching algorithm for video traffic. In the Part II, we offer the queueing analysis of SL/D/1/K called ‘quantization reduction method’. Comparing the queueing performances of the DAR(1) model and the SLCC with that of a real video trace, we identify the effects of SRD and LRD in VBR video traffic on queueing performance. Simulation results show that Markoivian models can estimate network performances fairly accurately under a moderate traffic load and buffer condition, whereas LRD may have a significant effect on queueing behavior under a heavy traffic load and large buffer condition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.39 no.6
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• pp.869-875
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• 2019

The service level of the roundabout is estimated through an analytic model using the geometrical characteristics and parameter values obtained from the observations. Although a lot of researches have been conducted on the rotational intersection through an analytical model, the case of variable combinations is enormous, suggesting the range and service level of appropriate traffic volume according to the case study or limited characteristics through simulation. Therefore, in this study, the roundabout analysis model was constructed by using Visual Basic Application to make variable adjustment more easily. The constructed model analyzes traffic conditions according to various situations and analyzes the characteristics of roundabouts. As the result of analysis, the more the ratio of left turn and U-turn, the more the traffic distribution of each approached road was biased to one side, the limit traffic volume of the roundabout decreased and congestion appeared quickly. In particular, the more uneven the distribution of traffic was, the less the Saturation traffic volume was affected by the turnover rate.

• Journal of Korean Society of Transportation
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• v.32 no.5
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• pp.497-502
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• 2014

As ground air traffic control at the airport is one of the most important tasks in air transport, attention to the development of a related simulator has expanded all around the world. For this reason, this research describes the characteristics and advantages of this advanced aerodrome traffic control simulator, developed in South Korea, as well as its linkage with A-SMGCS, which is planned to be developed in the future. One of the characteristics of this simulator is that it is possible to train an air traffic controller independently, especially under various conditions such as in different weathers and normal or abnormal circumstances. Therefore, this aerodrome traffic control simulator, through the comprehensive training under various conditions, will contribute to aviation safety and airport capacity enhancement training.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2022.10a
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• pp.110-113
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• 2022

Nowadays, breaking through the conventional traffic signal control method based on mathematical optimization, artificial intelligence began to be used in the area. In response to this trend, many studies are ongoing to figure out how to utilize AI technology properly for traffic signal optimization. They just simply focus on which method will work well besides lots of machine learning techniques and abandon the reward function engineering. In many cases, the reward function consists of the average delay of the vehicles in the intersection. However, this may lead to AI's misunderstanding about the traffic signal control: what AI regards as a good situation may not be realistic. Even the reward function itself may not meet the service level. Therefore, this study analyzes the problems of previous reward functions and will suggest how to reward function can be enhanced.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.2
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• pp.1-5
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• 2007

Wavelength-division multiplexed (WDM) networks are emerging to be the right choice for the future transport networks. In WDM networks, the optical layer provides circuit-switched lightpath services to the client layer such as IP, SONET and ATM. The set of lightpaths in the optical layer defines the virtual topology. Since the optical switches are reconfigurable, the virtual topology can be reconfigured in accordance with the changing traffic demand pattern at theclient layer in order to optimize the network performance. We present a new approach to the virtual topology reconfiguration and loadbalancing problem for wavelength-routed, optical wide-area networks under dynamic traffic demand. By utilizing the measured Internet backbone traffic characteristics, our approach follows the changes in traffic without assuming that the future traffic pattern is known. For the simulation traffic modeling, we collected the data from real backbone traffic. Experiments show that the standard deviation compared to previous technique is reduced.

• Journal of Korean Institute of Industrial Engineers
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• v.23 no.1
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• pp.235-247
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• 1997

In this study, the performance of ATM multiplexer with MPEG(Motion Pictures Experts Group) video is analyzed by considering the effect of the MPEG GOP(Group of Pictures) structure. By assuming that frame starting times are synchronized, aggregated traffics are considered to be transmitted at the beginning of each frame time units. The aggregated number of cells generated during a frame time unit is, therefore, derived from distributions of individual sources. The stationary probability of buffer occupancy can be easily obtained by using a property of the periodicity of aggregated traffics. Simulation approach is also used to determine the traffic load for a given probability of satisfying QoS(Quality of Service).

• Journal of the Korea Society for Simulation
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• v.18 no.4
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• pp.39-47
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• 2009

Recently, the threat of DDoS attacks is increasing and many companies are planned to deploy the DDoS defense solutions in their networks. The DDoS attack usually transmits heavy traffic data to networks or servers and they cannot handle the normal service requests because of running out of resources. Since it is very hard to prevent the DDoS attack beforehand, the strategic plan is very important. In this work, we have conducted modeling and simulation of the DDoS attack by changing the number of servers and estimated the duration that services are available. In this work, the modeling and simulation is conducted using OPNET Modeler. The simulation result can be used as a parameter of trade-off analysis of DDoS defense cost and the service's value. In addition, we have presented a way of estimating the cost effectiveness in deployment of the DDoS defense system.

• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.959_960
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• 2009

Worldwide problem, due to the depletion of energy to power more efficient use of the same capacity to improvise for the use of LED brightness is growing. Recent advances in LED technology have lead to LEDs' widespread use in outdoor-signal applications, such as in traffic and railroad signals. Likewise, for large system design and production of issues leading to the simulation should be performed with less effort than to create a system that is reliable. In this paper a wide field of use to more accurately simulate a LED, and easy to use PSPICE can be used as general-purpose use of the LED device modeling. According to a particular LED, the device easy to use basic input variables to the values of library. In order to determine the behavior of the library to provide basic diode device, compared with PSPICE simulations confirm the accuracy of the simulation was performed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.5
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• pp.37-45
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• 2004

As Internet technologies are mature, many new applications that are different characteristics are emerging. Recently we see wide use of P2P(Peer to Peer) applications of which traffic shows different statistical characteristics compared with traditional application such as web(HTTP) and FTP(File Transfer Protocol). In this paper, we measured subscriber network of KT(Korea Telecom) to analyze P2P traffic characteristics. We show flow characteristics of measured traffic. We also estimate Hurst parameter of P2P traffic and compare self-similarity with web traffic. Analysis results indicate that P2P traffic is much bustier than web traffic and makes both upstream traffic and downstream traffic be symmetric. To predict parameters related QoS such as packet loss and delays we model P2P traffic using two self-similar traffic models and predict both loss probability and mm delay then compare their accuracies. With simulation we show that the self-similar traffic models we derive predict the performance of P2P traffic accurately and thus when we design a network or evaluate its performance, we can use the P2P traffic model as reference input traffic.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.295-303
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• 2004

In this Paper, we discuss an active TCP link of unsynchronized transmission mode network in two-way traffic and the Improvement of its traffic patron thorough the network pathway of protocol is shown. This is because the traffic pattern is performed on the basis of existing windows which are distributing information in several periods of time in the way of interfacing LTS control module, which is controlling by an information of exceeding the time limit of feedback loop determined by RTP, with TCP. The simulation to utilize this efficiently is performed with the circumstance of bench mark based on physical modeling of the self-similarity traffic in the performance of TCP. In this paper, we use a methodology to understand and evaluate the effect of change of transmitting protocol in sticks under the condition of the self-similar traffic in two-way network and it is shown that an improvement of congestion control by self-similarity under a heavy condition.