• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.337-343
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• 2015

This paper investigates the ventilation characteristics in a two-dimensional underground network junction composed of four main lines interconnected by eight ramps. Simple one-dimensional models cannot be applied to network junctions since there are interferences of traffic piston effects in the main lines and at the ramps. A numerical algorithm was developed to analyze the pressure and airflow distributions iteratively. The Darcy-Weisbach equation was used to calculate the piston effects by traffic flows, and a Hardy Cross iteration was conducted for network analysis at the interconnected junction. The results show interesting ventilation characteristics and CO concentration distributions depending on system parameters such as vehicle speed, tunnel diameter, and other junction configurations.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.31 no.3
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• pp.229-238
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• 2013

Development of methodologies to generate the small scale map from the large scale map using map generalization has huge importance in management of the digital topographic map, such as producing and updating maps. In this study, the selection methodology of map generalization for the road network data in digital topographic map is investigated and evaluated. The existing maps with 1:5,000 and 1:25,000 scales are compared and the criteria for selection of the road network data, which are the number of objects and the relative importance of road network, are analyzed by using the T$\ddot{o}$pfer's radical law and Logit model. The selection model derived from the analysis result is applied to the test data, and the road network data of 1:18,000 and 1:72,000 scales from the digital topographic map of 1:5,000 scale are generated. The generalized results showed that the road objects with relatively high importance are selected appropriately according to the target scale levels after the qualitative and quantitative evaluations.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.2
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• pp.307-318
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• 2015

In this study, the efficiency of two-dimensional inundation analysis using road network was demonstrated in order to reduce the simulation time of numerical model in urban area. For this objective, three simulation conditions were set up: Case 1 considered only inundation within road zone, while Case 2 and 3 considered inundation within road and building zone together. Accordingly, Case 1 used grids generated based on road network, while Case 2 and 3 used uniform and non-uniform grids for whole study area, respectively. Three simulation conditions were applied to Samsung drainage where flood damage occurred due to storm event on Sep. 21, 2010. The efficiency of suggested method in this study was verified by comparison the accuracy and simulation time of Case 1 and those of Case 2 and 3. The results presented that the simulation time was fast in the order of Case 1, 2 and 3, and the fit of inundation area between each case was more than 85% within road zone. Additionally, inundation area of building zone estimated from inundation rating index gave a similar agreement under each case. As a result, it is helpful for study on real-time inundation forecast warning to use a proposed method based on road network and inundation rating index for building zone.

• Tunnel and Underground Space
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• v.28 no.1
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• pp.111-124
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• 2018

The purpose of this study is to analyze ventilation design factor for network-type double-deck road tunnel that have been developed actively around the world. A numerical analysis was carried out through computational fluid dynamics (CFD) to derive shock loss coefficient that occurs due to the change in cross sectional area at both merging section and diverging section. The model used for the numerical analysis is real-scale model and the reliability of the result is secured by comparing with the coefficient of the previous studies. As a result of this study, shock loss coefficient was calculated depending on the change in cross-sectional area ratio and was higher than the result of previous studies in case of both merging section and diverging section. It is considered that the characteristics of the geometrical structure of network-type double-deck road tunnel have a great impact on shock loss coefficient. Therefore, the result of this study is expected to be helpful for more accurate ventilation design of network-type double-deck road tunnel.

• Journal of Environmental Impact Assessment
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• v.14 no.5
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• pp.317-335
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• 2005

This paper is primarily intended to propose a new concept of "aggregate control of road density" which is defined as the area-wide road surface per watershed area. An empirical study for experimental sites was conducted to confirm how a standard GIS technology can be used to assist in estimating the road density in terms of total volume threshold control. Guidelines for a replicable methodology are presented to provide a strong theoretical basis for the standardization of factors involved in the estimation of the road space threshold; the meaningful classification of road types, delination of watershed boundary, interpretation for distribution trends of road density etc. A variety of visual maps using overlay analysis can be generated over large areas quickly and easily to show the fact that some degree of road space already exists in the experimental sites. They could be used as an evidence to limit further construction of road network in comparison with other tributary watershed. It is anticipated that this research output could be used as a valuable reference to confirm the potential of introducing the new concept of "site specific road density" to support more scientific and objective decision-making in the process of road construction project.

• Journal of Korean Society of Forest Science
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• v.102 no.1
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• pp.143-155
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• 2013

In order to establish efficient timber harvesting system and provide the necessary data for the system establishment, the techniques to identify areas possible of the yarding-operation and design forest-road networks were newly developed and the applicability of the techniques are tested in this study. The new techniques were developed based on ArcGIS, particularly with utilizing the Viewshed Analysis Tool. From the results of the identification of the possible yarding-operation areas, it is found that the percentage of possible yardingoperation area decreases with the increment of maximum yarding distance due to terrestrial effects. When forest road networks are extended in impossible yarding-operation sites, the area of possible yarding-operation sites increases. If a forest road network is newly designed, its overall extension is altered, resulting in changes in the possible yarding-operation areas. Through the comparative analysis among the different possible yardingoperation areas from different forest road networks, the maximization of the yarding-operation possible area can be achieved. The results from this study can be utilized for establishing more efficient timber-harvesting system and developing GIS-based programs to manage the system.

• Journal of Korean Society for Geospatial Information Science
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• v.21 no.4
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• pp.143-150
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• 2013

The purpose of this study is to suggest the methodology to develop variable-scale network model, which is able to induce large-scale road network in detailed level corresponding to small-scale linear objects with various abstraction in higher level. For this purpose, the definition of terms, the benefits and the specific procedures related with a variable-scale model were examined. Second, representation level and the components of layer to design the variable-scale map were presented. In addition, rule-based data generating method and indexing structure for higher LoD were defined. Finally, the implementation and verification of the model were performed to road network in study area (Jeju -do) so that the proposed algorithm can be practical. That is, generated variable scale road network were saved and managed in spatial database (Oracle Spatial) and performance analysis were carried out for the effectiveness and feasibility of the model.

• The Journal of Bigdata
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• v.2 no.2
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• pp.1-7
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• 2017

Intelligent transportation system (ITS) has been introduced to maximize the efficiency of operation and utilization of the urban traffic facilities and promote the safety and convenience of the users. With the expansion of ITS, various traffic big data such as road traffic situation, traffic volume, public transportation operation status, management situation, and public traffic use status have been increased exponentially. In this paper, we derive structural characteristics of urban traffic according to the vehicle flow by using big data network analysis. DSRC (Dedicated Short Range Communications) data is used to construct the traffic network. The results can help to understand the complex urban traffic characteristics more easily and provide basic research data for urban transportation plan such as road congestion resolution plan, road expansion plan, and bus line/interval plan in a city.

• Journal of Korean Society for Atmospheric Environment
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• v.29 no.4
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• pp.447-458
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• 2013

The present operating system for the atmospheric monitoring network in the city of Seoul, Korea, has been established since the late 90s by the Korean Ministry of Environment (KMOE). In this research, it was evaluated by the multi-statistical approaches through combinations of time series analysis, correlation matrix, and multiple cluster analysis. Finally, road traffic including resuspended materials can be one of the main sources of particulate matter in the atmosphere. Based on its importance, it will be significant challenges in quantitative evaluation of its contribution to airborne concentrations. The future directions for their amendments such as a new management plan for the source of road dust (including car emissions) were devised and proposed based on the statistical judgements derived in this research.

• Structural Monitoring and Maintenance
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• v.5 no.3
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• pp.363-377
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• 2018

The proper functioning of critical points on transport infrastructure is decisive for the entire network. Tunnels and bridges certainly belong to the critical points of the surface transport network, both road and rail. Risk management should be a holistic and dynamic process throughout the entire life cycle. However, the level of risk is usually determined only during the design stage mainly due to the fact that it is a time-consuming and costly process. This paper presents a simplified quantitative risk analysis method that can be used any time during the decades of a tunnel's lifetime and can estimate the changing risks on a continuous basis and thus uncover hidden safety threats. The presented method is a decision support system for tunnel managers designed to preserve or even increase tunnel safety. The CAPITA method is a deterministic scenario-oriented risk analysis approach for assessment of mortality risks in road tunnels in case of the most dangerous situation - a fire. It is implemented through an advanced risk analysis CAPITA SW. Both, the method as well as the resulting software were developed by the authors' team. Unlike existing analyzes requiring specialized microsimulation tools for traffic flow, smoke propagation and evacuation modeling, the CAPITA contains comprehensive database with the results of thousands of simulations performed in advance for various combinations of variables. This approach significantly simplifies the overall complexity and thus enhances the usability of the resulting risk analysis. Additionally, it provides the decision makers with holistic view by providing not only on the expected risk but also on the risk's sensitivity to different variables. This allows the tunnel manager or another decision maker to estimate the primary change of risk whenever traffic conditions in the tunnel change and to see the dependencies to particular input variables.