• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.65 no.12
• /
• pp.2046-2052
• /
• 2016

Ramp metering is one of the most efficient and widely used control methods for an intelligent transportation management system on a freeway. Its objective is to control and upgrade freeway traffic by regulating the number of vehicles entering the freeway entrance ramp, in such a way that not only the alleviation of the congestion but also the smoothing of the traffic flow around the desired density level can be achieved for the maintenance of the maximum mainline throughput. When the cycle of the signal detection is larger than that of the system process, the density tracking problem needs to be considered in the form of the discrete-time system. Therefore, a discrete-time sliding mode control method is proposed for the ramp metering problem in the presence of both input constraint in the on-ramp and exogenous disturbance in the off-ramp considering the random behavior of the driver. Simulations were performed using a validated second-order macroscopic traffic flow model in Matlab environment and the simulation results indicate that proposed control method can achieve better performance than previously well-known ALINEA strategy in the sense that mainstream flow throughput is maximized and congestion is alleviated even in the presence of input constraint and exogenous disturbance.

• International Journal of Highway Engineering
• /
• v.16 no.1
• /
• pp.111-118
• /
• 2014

PURPOSES : This study performs fundamental research on ramp-metering design criteria. METHODS : We carefully review previous studies in terms of ramp-metering design criteria and then consider applicability in Korea. For this, traffic simulation model is employed to analyze actual effect according to specific location of stop-line when implementing ramp-metering. RESULTS : When a stop-line moving forward with a 50m interval, travel speed at mainline relative to current stop-line location tends to decrease. However, traveling speed at approach roads increase about 5~18% under the same condition. When a stop-line location moving backward with a 50m interval, mainline travel speed increase approximately 17~32% whereas traveling speed at approach roads decrease. All cases are compared with the current stop-line location. CONCLUSIONS : We believe that both cases are useful with respect to freeway management. For example, moving forward a stop-line case can be used management for queuing area at ramp section and approach roads. Moving backward a stop-line case can be used for traffic control, focusing on mainline of freeways.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.15 no.6
• /
• pp.102-115
• /
• 2016

In this study, a scheme of ramp metering that uses Off-ramp Exit Percentage instead of the O/D table required for systems of integrated control of ramps at the target freeway segment is presented. The segment from Gyeyang IC to Jangsu IC on the Seoul Outer Ring Expressway was selected for the study because the segment frequently shows large volume of traffic on the short distance between the two ICs requiring an integrated on-ramp control by taking the traffic situation on an entire expressway into account despite an unavailability of O/D data. Thus the information of Off-ramp Exit Percentage at each IC were collected instead of securing the O/D table through actual survey, and the congestion on the segment was analyzed to identify the validity of the use of off-ramp traffic instead of O/D data. In addition, the scheme of ramp metering that exploits the off-ramp traffic information was prepared through simulations conducted in a way supporting the traffic control for respective access roads thereof by taking traffic situations and queues on each ramp into account. The results obtained from the simulation analyses revealed an improved level of travel speed and traffic volume on the main line and validated the use of off-ramp traffic instead of the O/D table for the ramp metering.

• The Journal of The Korea Institute of Intelligent Transport Systems
• /
• v.10 no.2
• /
• pp.9-21
• /
• 2011

The ramp metering strategy is one of the effective ways to solve the freeway traffic congestion in peak time periods. The study was initiated with assurance that the traffic conditions of ramp and mainline that mitigate the congestion would exist. Under the moderate traffic volume levels, ramp metering is expected to improve the quality of freeway operation. To derive a range of traffic condition, three operation strategies(Do nothing, ramp metering, minimum ramp control) were set up and the ALINEA algorithm was implemented with microscopic traffic simulator "VISSIM". The volumes of mainline and ramp are key parameters for the simulation scenarios. Measures of effectiveness for the study include mainline density and average vehicle speed. Operation boundaries in terms of traffic volume were proposed for operating ramp metering strategy. The results show that under the proposed traffic conditions the ramp metering was more successful to increase average vehicle speeds. Traffic controls under the operation boundaries of traffic levels give significant effects for density and average vehicle speed. The outcomes of this study would be useful to improve the performance of ramp metering strategies.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.39 no.2
• /
• pp.361-367
• /
• 2019

Ramp metering is a traffic management technique that reduces the congestion of Expressway by controlling vehicles entering the highway. It is widely used outside the country, and Korea is also operating in seven sites (Seoul Ring Expressway). Ramp metering has the advantage of reducing congestion of Expressway, but there are disadvantages, as queuing occurs because vehicles are waiting for ramp, and the ramp queue affects adjacent roads at rush hour. To solve this problem, we improved the ramp metering algorithm to reduce the metering rate more spaces on ramp and to increase the metering rate less spaces. In order to evaluate this, the combined evaluation index was used and it was found that the result satisfied the equity and efficiency at the same time.

• Journal of Digital Convergence
• /
• v.12 no.1
• /
• pp.405-414
• /
• 2014

It is very important to IT users that the Cloud service provides dynamic extension of IT resources and cost-saving. However, the reliability for Cloud service hinders utilizing Cloud service actively. Existing studies on assessment program for Cloud Service are executed by extracting information security assessment articles and adding features of cloud services by referencing ISO/IEC 27001:2005. This paper will review the recently released ISO/IEC 27001:2013 for the addition, reduction, and changing of articles for Controls and Control objectives. Comparative analysis for the Controls of ISO/IEC 27001:2013 with those of CSA CCMv.3, FedRAMP which is an assessment program for Cloud service will suggest Control Objects of Information Security Management System for related Cloud service. The suggestion of Controls will be an important reference index for the security policy of companies which manage the information security management system based on Cloud service.

• Journal of Korean Society of Archives and Records Management
• /
• v.14 no.2
• /
• pp.61-82
• /
• 2014

Archival authority records support users in accessing and understanding archival information. The creator of the archives, on the other hand, is also the creator of other informative materials, including published products, and the users want to access information in a seamless manner. Moreover, the authority record has common attributes with the authority records for bibliographic control as well as its distinctive characteristics. Therefore, this research aims to link legacy authority records for constructing and expanding archival authority records and provide the expanded archival records to the Web environment, including Wikipedia, for data sharing. Finally, some issues and suggestions for further research based on the findings that resulted from experimental linking and sharing are discussed.

• Journal of Korean Society of Transportation
• /
• v.28 no.3
• /
• pp.29-37
• /
• 2010

Ramp metering control is the most representative strategy of uninterrupted flow control and management system. Ramp metering is to adjust vehicles entering an expressway in such a way that expressway mainline maintains flow stability by regulating ramp vehicles. The effect of two metering strategies, single-entry metering and platoon metering, on mainstream under the same metering rate with pre-timed metering are analyzed by micro-simulation. Platoon metering shows lower performance than single-entry metering under the same metering rate in terms of speed, density, and delay, causes earlier breakdown than single-entry metering. It indicates that the selection of metering type has critical importance as the flow of mainline is high.

• Journal of Korean Society of Transportation
• /
• v.17 no.4
• /
• pp.59-69
• /
• 1999

A Freeway corridor is a network consisting of a few Primary longitudinal roadways (freeway or major arterial) carrying a major traffic movement with interconnecting roads which offer the motorist alternative paths to his/her destination. Control measures introduced to ameliorate traffic performance in freeway corridors typically include ramp metering at the freeway entrances, and signal control at each intersections. During a severe freeway incident, on-ramp metering usually is not adequate to relieve congestion effectively. Diverting some traffic to the Parallel surface street to make full use of available corridor capacity will be necessary. This is the purpose of the traffic management system. So, an integrated traffic control scheme should include three elements. (a)on-ramp metering, (b)off-ramp diversion and (c)signal timing at surface street intersections. The purpose of this study is to develop an integrated optimal control model in a freeway corridor. By approximating the flow-density relation with a two-segment linear function. the nonlinear optimal control problem can be simplified into a set of Piecewise linear programming models. The formulated optimal-control Problem can be solved in real time using common linear program. In this study, program MPL(ver 4.0) is used to solve the formulated optimal-control problem. Simulation results with TSIS(ver 4.01) for a sample network have demonstrated the merits of the Proposed model and a1gorithm.

• Journal of the Korean Society of Safety
• /
• v.34 no.5
• /
• pp.119-131
• /
• 2019

Among the themes for CSR(Corporate Social Responsibility), consumer issues include protecting the health and safety of consumers who purchase and use the products. In particular, ensuring product safety is a major theme of consumer issues for corporate social responsibility. Currently, the government implements the Electrical Appliances and Consumer Products Safety Control Act for product safety management and selects products that may harmful to consumers as safety control items, and manages the products by designating them as 4 types of safety certification, safety confirmation, supplier conformity verification, and safety standard compliance. In this paper, we propose management plans for the establishment of a more reasonable classification type of safety management target for 48 items of consumer products to be controlled by the act, and confirm the validity of the plan. First, we perform cluster analysis using data for CISS (Consumer Injury Surveillance System) to derive a new classification type of the safety management target. Next, we compare the results of the cluster analysis with the classification type of the act and the existing scenario classification method RAS (Risk Assessment by Scenario) and the causal network method RAMP (Risk Assessment Method based on Probability). Based on these results, we propose two new plans of safety management target classification and verify its validity.