• Journal of KIISE:Information Networking
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• v.31 no.1
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• pp.70-80
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• 2004

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). But, RED configuration has been a problem since its first proposal. This problem is that proposed configuration is only good for the particular traffic conditions studied, but may have detrimental effects if used in other conditions. 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 unstable for tile various traffic conditions. The inherent problem with these queue management algorithms is that they all use static parameter setting. In this paper, in order to solve this problem, a new active queue management algorithm called SQM(Stabilized Queue Management) is proposed. This paper shows that it is easy to parameterize SQM algorithm to perform well under different congestion scenarios. This algorithm can effectively reduce packet loss while maintaining high link utilizations and is good for the various traffic conditions.

• Journal of Information Technology Applications and Management
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• v.20 no.3_spc
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• pp.201-217
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• 2013

This paper analyzes the effect of network neutrality regulation on social welfare using the two-sided market under the network congestion. This paper deals with zero price rule regulation which means the price regulation on the side of content. The results are as follows : First, under the monopoly platform, internet use price, contents price, and the number of internet user and content provider are all decreasing as the network congestion increases. Second, under the monopoly platform internet use price, contents price, and the number of internet user and content provider are all increasing as the network capacity increases. Third, the price of internet use and contents internet use which maximize social welfare are increasing and the number of internet user and content provider are decreasing as the network congestion increases. Fourth, optimal network capacity for monopoly platform provider is less than socially optimal network capacity. Fifth, if network neutrality regulation is enforced, the price of internet use is higher than monopoly platform provider and the price of contents is lower than monopoly platform provider. Also, the number of internet user is less than monopoly platform provider and the number of content provider is more than that. By the way, when network congestion increases, internet use price, the number of internet user, and the number of content provider are decreasing. Sixth, network neutrality regulation is more effective for internet user side than contents provider when network congestion is considered. This means that network neutrality regulation is not effective for contents market side when network congestion is seriously large.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.6
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• pp.68-77
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• 2013

This study suggested experimental study results of congestion detection method for intruding vehicle enforcement system. This congestion detection method is developed to determine optimal operation criteria of intruding vehicle enforcement system as detecting traffic congestion. In ITS sector, traffic management systems generally have used a sectional travel speed for congestion detection. However, image sensors have high error rate of congestion detection because of speed error. This study suggested comprehensive congestion detection criteria based on speed and occupancy rate using field studies. As field study results, the proposed intruding vehicle enforcement system using image sensor is capable of accurately detecting the traffic congestion using sectional speed of 20km/h and occupancy rate of 60% as congestion detection criteria.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.177-183
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• 2007

Active queue management (AQM) refers to a family of packet dropping mechanisms for router queues that has been proposed to support end-to-end congestion control mechanisms in the Internet. The proposed AQM algorithm by the IETF is Random Early Detection (RED). The RED algorithm allows network operators simultaneously to achieve high throughput and low average delay. However. the resulting average queue length is quite sensitive to the level of congestion. In this paper, we propose the Refined Adaptive RED(RARED), as a solution for reducing the sensitivity to parameters that affect RED performance. Based on simulations, we observe that the RARED scheme improves overall performance of the network. In particular, the RARED scheme reduces packet drop rate and improves goodput.

• Korean Management Science Review
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• v.29 no.1
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• pp.131-141
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• 2012

The automated material handling systems today are playing ever more important roles in semiconductor/LCD fabrication facilities. Recently they became more flexible, intelligent, and speedy than in the past. The facilities have been fully automated because the size and weight of the unit loads used in the facilities were being increased beyond the limits that a human operator can handle. This research develops an efficient procedure to streamline the delivery of unit loads by the automated material handling system (AMHS). For this task, the research employs the event scheduling theory that has been successfully used in the both academia and industry. The developed procedure was applied to an actual LCD fabrication facility and improved the performance of an existing material handling system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4977-4996
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• 2016

The existence of excessively large and too filled network buffers, known as bufferbloat, has recently gained attention as a major performance problem for delay-sensitive applications. Researchers have made three types of suggestions to solve the bufferbloat problem. One is End to End (E2E) congestion control, second is deployment of Active Queue Management (AQM) techniques and third is the combination of above two. However, these solutions either seem impractical or could not obtain good bandwidth utilization. In this paper, we propose a Transmission Control Protocol（TCP）delayed window update mechanism which uses a congestion detection approach to predict the congestion level of networks. When detecting the network congestion is coming, a delayed window update control strategy is adopted to maintain good protocol performance. If the network is non-congested, the mechanism stops work and congestion window is updated based on the original protocol. The simulation experiments are conducted on both high bandwidth and long delay scenario and low bandwidth and short delay scenario. Experiment results show that TCP delayed window update mechanism can effectively improve the performance of the original protocol, decreasing packet losses and queuing delay while guaranteeing transmission efficiency of the whole network. In addition, it can perform good fairness and TCP friendliness.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.437-447
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• 2003

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) algorithm. However, RED algorithm simple but does not protect traffic from high-bandwidth flows, which include not only flows that fail to use end-to-end congestion control such as UDP flow, but also short round-trip time TCP flows. In this paper, in order to solve this problem, we propose a simple fairness queue management scheme, called AFQM(Approximate Fair Queue Management) algorithm, that discriminate against the flows which submit more packets/sec than is allowed by their fair share. By doing this, the scheme aims to approximate the fair queueing policy Since it is a small overhead and easy to implement, AFQM algorithm controls unresponsive or misbehaving flows with a minimum overhead.

• Journal of Korean Society of Transportation
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• v.17 no.1
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• pp.173-185
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• 1999

The purpose of this study is to develope a forecasting model to implement short-term Congestion Management Program (CMP) based on TDM strategies in Seoul. The CMP is composed of three elements: 1) setting a goal of short-term traffic management. 2) developing a model to forecast the impacts of TDM alternatives, and 3) finding TDM measures to achieve the goal To Predict the impacts of TDM alternatives, a model called SECOMM (SEoul COngestion Management Model) is developed. The model assumes that trip generation and distribution are not changing in a short term, and that only mode split and traffic assignment are affected by TDM. The model includes the parameter values calibrated by a discrete mode choice model, and roadway and transit networks with 1,020 zones. As a TDM measure implement, it affects mode choice behavior first and then the speeds of roadway network. The chanced speed again affects the mode choice behavior and the roadway speeds. These steps continue until the network is equilibrated. The study recommends that CMP be introduced in Seoul, and that road way conditions be monitored regularly to secure the prediction accuracy of SECOMM. Also, TDM should be the major Policy tools in removing short-term congestion problems in a big city.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.5
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• pp.1384-1396
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• 1998

This paper ivestigates the performance of a relative rate (RR) switch algorithm for the rate-based available bit rate (ABR) flow control in asynchronous transfer mode (ATM) networks. A RR switch may notify the network congestion status to the source by suing the congestion indication (CI) bit or no increase (NI)bit in the backward RM (BRM) cells. A RR switch can be differently implemented according to the congestion detectio and notification methods. In this paper, we propose three implementation schemes for the RR switch with different congestion detection and notification methods, and analyze the allowed cell rate (ACR) of a source and the queue length of a switch in steady state. In addition, we derive the upper and lower bounds for the maximum and minimum queue lengths for each scheme respectively, and evaluate the effects of the ABR parameter values on the queue length. Furthermore, we suggest the range of the rage increase factor (RIF) and rate decrease factor (RDF) parameter values which can prevent buffer overflow and underflow at a switch.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.74-79
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• 2016

The Seoul Metropolitan Subway, which started operating in 1974, plays a major role in transporting 7,289 thousands passengers daily. This trend of a steadily increase in passengers from 2012 has increased the congestion rate because of the limited capacity and time. To solve this problem, Seoul city is consistently working on improving the subway facilities, such as the construction of a detour path. This project, however, has only a slight effect on improving the congestion rate and is too expensive to construct the facilities. Hence, this study suggests The Congestion Standardization System based on the IoT for improving the subway congestion rate. Based on the system, the expected effect analysis was performed, which resulted in a decrease in ride passengers from 34 to 20. In addition, this expected effect analysis shows that the number of subway vehicles can increase from 20 to 24. The suggested system will have a significant effect on the efficiency of the management system.