• Journal of Institute of Control, Robotics and Systems
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• v.13 no.3
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• pp.263-267
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• 2007

This study proposes a new methodology to estimate the traffic capacity of a personal rapid transit(PRT) system. The proposed method comprises three steps. The first step models the guideway network(GN) of PRT as a digraph, where its node and link represent a station and a one-way guideway link between two stations, respectively. Given local vehicle control strategies, the second step formulates the local traffic capacities through the nodes and links of the GN model. The third step estimates the worst-case local traffic demands based on a shortest-path routing algorithm and an empty vehicle allocation algorithm. By comparing the traffic estimates to the local traffic capacities, we can determine the feasibility of the given GN in traffic capacity.

• Proceedings of the IEEK Conference
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• 2003.07a
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• pp.477-480
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• 2003

Packet losses in the Internet can dramatically degrade quality of multimedia streams. Forward Error Correction (FEC) is one of the best methods that can protect data from packet erasures by means of sending additional redundant information. Proposed control algorithm provides the possibility of receiving real-time multimedia streams of given quality wifth minimal traffic overhead. The traffic optimization is reached by adjusting packet size as well as block code parameters. Calculations and simulation results show that for non-bursty network conditions traffic optimization can lead to more than 50% bandwidth reduction.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.2 no.3
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• pp.389-399
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• 1998

The DMR-II shared-medium access control protocol was developed for the ATM access network users to supper the isochronous traffic and the non-isochronous traffic simultaneously under the bandwidth-skating environment. In this paper we analyze the performance of the DMR-II protocol by using both the analytical analysis and the simulation method. Under the ATM access network environment, the performance analysis result shows that the DMR-II protocol maintains the delay variation of the isochronous traffic beyond the threshold value, and satisfies the delay time criteria of the non-isochronous traffic by supporting the priority service. Moreover the result shows high network utilization over 130% due to the destination release mechanism of the DMR-II protocol.

• Journal of Korean Society of Transportation
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• v.27 no.1
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• pp.27-34
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• 2009

The operational effect of traffic signal control improvement was evaluated using the Two-Fluid Model. The parameters engaged in the Two-Fluid Model becomes food indicators to measure the quality of traffic flow due to the improvement of traffic signal operation. A series of experiment were conduced for the 31 signalized intersections in Uijeongbu City. To estimate the parameters in the Two-Fluid Model the trajectory informations of individual vehicles were collected using the CORSIM and Run Time Extension. The test results showed 35 percent decrease of average minimum trip time per unit distance. One of the parameters in the Two-Fluid Model is a measure of the resistance of the network to the degraded operation with the increased demand. The test result showed 28 percent decrease of this parameter. In spite of the simulation results of the arterial flow, it was concluded that the Two-Fluid Model is useful tool to evaluate the improvement of the traffic signal control system from the macroscopic aspect.

• Journal of Digital Contents Society
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• v.5 no.2
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• pp.151-156
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• 2004

This paper presents process model to accomplish traffic engineering in Internet. The process model consists of 4 stages. The first stage is the formulation of a control policy dominated network operation. The second stage is the observation of the network state through a set or monitoring functions. The third stage is the characterization or traffic and analysis or the network state. The final stage is the optimization of network performance. the four stages of the process model defined above are iterated.

• Journal of Computing Science and Engineering
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• v.1 no.1
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• pp.31-55
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• 2007

Contemporary end-servers and network-routers rely on traffic shaping to deal with server overload and network congestion. Although such traffic shaping provides a means to mitigate the effects of server overload and network congestion, the lack of cooperation between end-servers and network-routers results in waste of network resources. To remedy this problem, we design, implement, and evaluate NetDraino, a novel mechanism that extends the existing queue-management schemes at routers to exploit the link congestion information at downstream end-servers. Specifically, NetDraino distributes the servers' traffic-shaping rules to the congested routers. The routers can then selectively discard those packets-as early as possible-that overloaded downstream servers will eventually drop, thus saving network resources for forwarding in-transit packets destined for non-overloaded servers. The functionality necessary for servers to distribute these filtering rules to routers is implemented within the Linux iptables and iproute2 architectures. Both of our simulation and experimentation results show that NetDraino significantly improves the overall network throughput with minimal overhead.

• Journal of Korea Society of Digital Industry and Information Management
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• v.18 no.4
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• pp.23-30
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• 2022

Recently, traffic congestion and environmental pollution have occurred due to population concentration and vehicle increase in large cities. Various studies are being conducted to solve these problems. Most of the traffic congestion in cities is caused by traffic signals at intersections. This paper proposes a dynamic traffic light control (DTLC) scheme to support safe vehicle operation and smooth traffic flow using real-time traffic information based on VANET. DTLC receives instantaneous speed and directional information of each vehicle through road side units (RSUs) to obtain the density and average speed of vehicles for each direction. RSUs deliver this information to traffic light controllers (TLCs), which utilize it to dynamically control traffic lights at intersections. To demonstrate the validity of DTLC, simulations were performed on average driving speed and average waiting time using the ns-2 simulator. Simulation results show that DTLC can provide smooth traffic flow by increasing average driving speed at dense intersections and reducing average waiting time.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3098-3103
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• 2009

In this paper, self-similar characteristics over statistical approaches and real-time Ethernet network traffic measurements are estimated. It is also shown that the self-similar traffic reflects real Ethernet traffic chareacteristics by comparing TCP-MT source model which is exactly self-similar model to the traditional Poisson model.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.05a
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• pp.1397-1400
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• 2005

Multiprotocol Label Switching is an initiating IETF that integrated Layer2 information network links(bandwidth, latency, utilization) to Layer 3(IP) with a particular autonomous system(or ISP) in order to simplify and improve IP-packet exchange. MPLS gives network operators a grate deal of flexibility to divert and route traffic around link failures, congestion, and bottlenecks. The MPLS has advantages that will be able to solve existing problem of Network that ISP have had IP, QoS, Gigabit forwarding and traffic engineering. The purpose of this study is to measure Access-list and the capacities of PE Router that would operate as MPLS. Many ISP using MPLS service to handle high-speed internet traffic with apply to firewall in future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.3
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• pp.417-423
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• 2024

This study compared and analyzed the importance of command priority between railway traffic controllers through pairwise comparison of AHP analysis. 27 railway traffic controllers working on metropolitan railway control center, urban railway control center, and unmanned driving control center responded. As a result of the analysis, all the railway traffic controllers generally recognized the train driving control and train signal control as the most important priorities. For the controller in the manned driving system, a train driving control was the highest at 0.375. On the other hand, the controller based on unmanned driving recognized train signal control as the highest priority at 0.469. In the result of the AHP analysis considering all the variables, the braking system was the highest priority at 0.19 based on manned train driving. On the other hand, the controller based on unmanned train driving recognized wired and wireless network systems and SCADA as the highest priority at 0.267.