• International Journal of Control, Automation, and Systems
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• v.5 no.3
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• pp.317-323
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• 2007

Quality of Service (QoS) in the Internet depends on queuing and sophisticated scheduling in routers. In this paper, we address the issue of managing traffic flows with different priorities. In our reference model, incoming packets are first classified based on their priority, placed into different queues with different capacities, and then multiplexed onto one router link. The fuzzy nature of the information on Internet traffic makes this problem particularly suited to fuzzy methodologies. We propose a new solution that employs a fuzzy inference system to dynamically and efficiently schedule these priority queues. The fuzzy rules are derived to minimize the selected Lyapunov function. Simulation experiments show that the proposed fuzzy scheduling algorithm outperforms the popular Weighted Round Robin (WRR) queue scheduling mechanism.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.364-367
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• 2008

Many different types of network equipments are deployed in a large-scale IP network. In this operating environment, network service providers suffer from difficulty in controlling various equipments simultaneously in case network faults happen in their overall or regional network due to physical link failure or abnormal traffic. This paper presents a policy-based methodology to control many different types of network equipments at the same time in abnormal cases. The key idea is that NMS(Network Management System) keeps vendor-neutral control policies in normal times and that when an abnormal case occurs in network, NMS transforms the selected policy into vendor-specific control commands and enforces them to various equipments simultaneously.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.889-898
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• 2000

In order to support various broadband multimedia servies in the future, we designed a well balanced WDM backbone network. In Korean network traffic environment, six regional centers are selected, link capacities between the regional centers are estimated from the PDI traffic model, and the overall network configuration is designed for the all-optical backbone network. Also, we designed a basic configuration to be able to protect minimum communication capability against link failure. A simulation study is carried out to verify the desired performance of the designed WDM backbone network. Simulation results show that performance of the backbone network is well balanced to support various communication services in Korea in the mid 2000s

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.4
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• pp.335-342
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• 2000

This study is to integrate and to analyzegraphic and attribute data in features which should be preceding for the ITS construction. A 1:5000 scale map as a national basemap was used and was checked for feasibility. For the convenience of position confirmation, the analysis component was developed and was linked to addresses. Also, the attribute information was considered on the shortest route, and optimal route was selected by investigating traffic volumes on main crossroads depending on the time zone. The optimal route could be selected by analyzing user's demands, position and statistical data, and the position information could be provided efficiently by combining the graphic information with the land register information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.183-191
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• 2004

Single shortest path routing is known to perform poorly for Internet traffic engineering (TE) where the typical optimization objective is to minimize the maximum link load. Splitting traffic uniformly over equal cost multiple shortest paths in OSPF and IS-IS does not always minimize the maximum link load when multiple paths are not carefully selected for the global traffic demand matrix. However, among all the equal cost multiple shortest paths in the network, a set of TE-aware shortest paths, which reduces the maximum link load significantly, can be found and used by IP routers without any change of existing routing protocols and serious configuration overhead. While calculating TE-aware shortest paths. the destination-based forwarding constraint at a node should be satisfied, because an IP router will forward a packet to the next-hop toward the destination by looking up the destination prefix. In this paper, we present a problem formulation of finding a set of TE-aware shortest paths in ILP, and propose a simple heuristic for the problem. From the simulation results, it is shown that TE-aware shortest path routing performs better than default shortest path routing and ECMP in terms of the maximum link load with the marginal configuration overhead of changing the next-hops.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.111-120
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• 2018

This study focuses on utilizing drones for performance evaluation of ITS detectors and analyzing economic feasibility when performance evaluation is conducted by the traffic management center's own personnel using drones. The study sites were selected from DSRC, video detector, and radar detector locations and drone filming was conducted to obtain travel speed, queue length, and delay time and compare with the detector data. It was shown that drones can be very effectively used to evaluate performance of major ITS detectors such as DSRC and video detectors. In addition, it was analyzed that a drone operated by the traffic management center's own personnel provides very economic solution for ITS detector performance evaluation when compared to consignment by external agencies.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.1
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• pp.1-16
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• 2020

With the advent of the fourth industrial revolution era, there has been a growing interest in deep learning using big data, and studies using deep learning have been actively conducted in various fields. In the transportation sector, there are many advantages to using deep learning in research as much as using deep traffic big data. In this study, a short -term travel speed prediction model using LSTM, a deep learning technique, was constructed to predict the travel speed. The LSTM model suitable for time series prediction was selected considering that the travel speed data, which is used for prediction, is time series data. In order to predict the travel speed more precisely, we constructed a model that reflects both temporal and spatial effects. The model is a short-term prediction model that predicts after one hour. For the analysis data, the 5minute travel speed collected from the Seoul Transportation Information Center was used, and the analysis section was selected as a part of Gangnam where traffic was congested.

• Korean Management Science Review
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• v.17 no.3
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• pp.61-71
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• 2000

Due to the potential growing capability that reflects future value, the market value of internet business companies (IB) are still evaluated high although major players like Amazon continuously suffer losses. Then, how do investors valuate the potential growing capabilities given that traditional financial/accounting based valuation approaches seem to be inappropriate for IB. This study attempts to provide an answer to this issue. We, therefore, analyzed the predictability of various accounting and non-accounting variables for IB value. These include book value, net income, unique visitors, page view, reach rate, public float and institutional holdings. Because of being in infant stage and difficulties in obtaining necessary web traffic data, sample of 20 pure IB were selected from Korea Stock Exchange Market, KOSDAQ, and informal market. The results of this study showed that web traffic date had the strongest relationship with IB value. In particular, unique visitors and reach rate were found to be best predictors for IB value while page view was reasonable indicator. Interestingly, net income was not found to related to IB value. This calls for an attention to the typical characteristics of IB that my hinder the usage of traditional valuation approaches for IB. Another results revealed that none of both public float and institutional holdings was significantly associated with IB value, indicating market’s supply-demand factors were less important than traffic information.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.5
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• pp.148-162
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• 2023

The objective of this study is to derive the appropriate perception location for changes in driving behavior of autonomous vehicles in urban road environments based on traffic safety signs. For this purpose, 32 types of signs that induce changes in driving behavior were selected from currently used traffic safety signs and classified as three types according to changes in driving behavior. Based on this, three scenarios were designed: stop, speed change, and lane change scenarios. These were used to confirm the impact on traffic flow. As a result of the analysis, it was found that each scenario needs to receive information on traffic safety signs in advance to ensure changes in traffic flow and safety. Consequently, the appropriate perception location can be used as a basis for establishing standards for delivering message sets to autonomous vehicles or revising traffic safety signs for them. In addition, this study is expected to contribute to the establishment of safe and efficient driving strategies on urban roads as autonomous vehicles are introduced in the future.

• Journal of Auto-vehicle Safety Association
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• v.9 no.1
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• pp.19-24
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• 2017

This paper present a performance evaluation scenarios to assess the safety performance of autonomous emergency braking (AEB) system for cyclist collision. To guarantee the safety performance of AEB for cyclist, AEB system should be tested in various scenarios which can be occurred in real driving condition. For this, real-traffic car-to-cyclist collision data are analyzed to classify the real traffic collision scenarios. Using this information, typical car-to-cyclist collision scenarios are selected. Also, in order to develop the detail features of these collision scenarios, several accident cases related with these scenarios are explained. Based on these information, test scenarios which can describe the car-to-cyclist collisions occurred in Korea are proposed. For practicality and feasibility of the test scenarios, proposed scenarios should be designed to assess the safety performance of AEB system effectively. For this, some test scenarios are combined or removed based on the consideration about the effectiveness of each scenario to the assessment of the performance of AEB system. To confirm that the proposed test scenarios are realistic and physically meaningful, simulation is conducted using simple AEB system in proposed test scenarios.