• Economic and Environmental Geology
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• v.54 no.5
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• pp.495-503
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• 2021

Aggregate is a major natural resource used in SOC construction, such as housing, roads, ports, etc., and is a fundamental material for national construction. Although aggregates account for only about 4% of the construction cost, aggregates occupy about 80% of the construction volume and are essential factors that determine the quantity and quality of buildings. For river, underwater, riverbed, sea, and land aggregates, it is difficult to rapidly increase the production of aggregates when there is difficulty in supply and demand due to environmental problems and limited resources during production, whereas forest aggregates are relatively easy to increase production. Forest aggregates are considered promising as alternative aggregate resources in the future when reducing other aggregates due to their abundance of natural resources, and are an effective aggregate source that can flexibly respond to aggregate demand in accordance with well-organized plans and policies. This study proposed the plan for activating the development of forest aggregates in the case of long and short transport distances, which is a factor that has a great influence on the development, and measures for the current difficulties in forest aggregate development

• Journal of Korean Society for Quality Management
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• v.46 no.4
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• pp.899-910
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• 2018

Purpose: Generally, since the population density is lower in suburban areas, the distance to school is inevitably long. Therefore, schools in suburban areas often operate school buses to improve student welfare. However, since school buses are usually used only during going to and from school, the utilization rates are relatively low. Therefore, this study aims to establish integrated operation plan of public school bus covering all schools. Methods: It is necessary to decide which school buses will serve the specific demand node which want to go to certain school in order to design an integrated operation plan for school buses. Therefore, a mathematical model is developed for minimizing the total number of vehicles and the distance of transportation by reflecting the characteristics of school buses and students as constraints. To solve the proposed mathematical model, CPLEX, a commercial solver, is applied. Results: To validate and to confirm the proposed process, numerical example is designed with the comparison between before and after integrated operations of school buses in terms of total operation cost. The result shows that the integrated operation can lead the reduction of the number of school buses as well as the decreasing of the fuel cost. Conclusion: This study provides the quantitative method to perform the integrated operation of school buses in suburban areas. The optimal operation strategy is required because there are more complex decision-making elements considering the integrated operation. It is expected to apply this research result at real situation to expand this services based on an optimal operation.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.1D
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• pp.17-23
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• 2009

Due to the rapid increase of vehicles on the street, Korean society is facing worsening traffic congestions and air pollutions. Also, the oil price pickup has led to increasing need for the use of public transportation. In particular, transfering among public transportation may be a main factor for riders who are commuting for a long distance journey. In order to ensure such connectivity, transfer stations have been actively built in Korea. However, it would be necessary to shift those vehicles, from cars to public transportations by enhancing the users' satisfaction with public transportation through strategies for minimizing the users' waiting cost by building an efficient connective system between transportation modes as well as the preparation of aforementioned transfer stations. Therefore, this study aimed to develop an algorithm for minimizing transferring passengers' waiting costs based on service intervals of linked buses within the transfer facilities. In order to adjust the service interval, we calculated the total costs, involving the wait cost of transfer passengers and bus operation costs, and produced an allocation interval, that would minimize the costs. We selected a KTX departing from Seoul station, and a No. 6014 bus route in Gwangmyeong city where it starts from the Gwangmyeong station in order to for verifying the model. Then, the transfer passengers' total waitting cost was reduced equivalent to the maximum of 212 minutes, and it revealed that the model performed very effectively.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.837-847
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• 2019

Korea's long underground roads are being promoted around the metropolitan city center to realize advanced transportation networks. Many disaster prevention facilities are applied to secure fire safety of the closed and long-distance underground roads. As the facility response and fire suppression subjects are unclear, additional human and material damages from fire spread are inevitable. Therefore, in this study, we developed a remote automatic fire extinguishing system that uses the fire extinguishing water inside the fire hydrant to monitor the CCTV in the management room and sprays it directly to the fire site through automatic control. The design application method was studied through the performance improvement that can be put into practical use.

• Journal of Korean Society of Transportation
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• v.20 no.2
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• pp.47-58
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• 2002

This thesis is based on the speed variations which are observed both in a sing1e tunnel and a continuous tunnel. Kumdae II tunnel and Chiak I tunnel of Jungang Expressway are selected in order to analyze the characteristics of speed variations according to tunnel intervals I place importance on the computation of tunnel intervals according to the speed variations. there's a summary of the results. The results of the study reveal that speed changes occur both on 1km ahead of tunnel and within the tunnel. The speed change amounts to 7.1km/hr(6.7%) on these survey Points 2.7km/hr (2.9%) on access points, and from -3.6km/hr (-3.8%) to, +4.1km/hr(+4.7%) irregularly on egress points. The magnitude of speed chance appears small on the survey points where an interval of tunnel is short whereas the speed chance turn out to be rather significant on the points where the tunnel interval is long. The analysis of tunnel distances using multiple regression models shows that the appropriate tunnel distance turns out to be 732m. The distance of 732m seem to be providing a fecundation for uniform traffic flow in continuous tunnel conditions.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.4
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• pp.190-211
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• 2022

This study investigated the effect of the shape and height of road signs on detection performance when detecting road signs with LiDAR, which is recognized as an essential sensor for autonomous vehicles. For the study, four types of road signs with the same area and material and different shapes were produced, and a road driving test was performed by installing a 32Ch rotating LiDAR on the upper part of the vehicle. As a result of comparing the shape of the point cloud and the NPC according to the shape of the road sign, It is expected that a distance of less than 40m is required to recognize the overall shape of a road sign using 32Ch LiDAR, and shapes such as triangles and rectangles are more advantageous than squares in securing the maximum point cloud from a long distance. As a result of the study according to the height of the road sign, At short distances (within 20m), if the height of the sign is raised to more than 2m, it deviates from the vertical viewing angle of the LiDAR and cannot express the complete point cloud shape. However, it showed a negligible effect compared to the near-field height change. These research results are expected to be utilized in the development of road facilities dedicated to LiDAR for the commercialization of autonomous cooperative driving technology.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.209-221
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• 2009

Travel time estimation under given traffic conditions is important for providing drivers with travel time prediction information. But the present expressway travel time estimation process cannot calculate a reliable travel time. The objective of this study is to estimate the path travel time spent in a through lane between origin tollgates and destination tollgates on an expressway as a prerequisite result to offer reliable prediction information. Useful and abundant toll collection system (TCS) data were used. When estimating the path travel time, the path travel time is estimated combining the link travel time obtained through a preprocessing process. In the case of a lack of TCS data, the TCS travel time for previous intervals is referenced using the linear interpolation method after analyzing the increase pattern for the travel time. When the TCS data are absent over a long-term period, the dynamic travel time using the VDS time space diagram is estimated. The travel time estimated by the model proposed can be validated statistically when compared to the travel time obtained from vehicles traveling the path directly. The results show that the proposed model can be utilized for estimating a reliable travel time for a long-distance path in which there are a variaty of travel times from the same departure time, the intervals are large and the change in the representative travel time is irregular for a short period.

• Journal of the Korean association of regional geographers
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• v.6 no.1
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• pp.1-28
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• 2000

The purpose of this study is to clarify the suburbanization of manufacturing, and location and linkages of decentralized manufacturing from Metropolitan Pusan by means of case study on manufacturing location and linkages in the suburb of Metropolitan Pusan. Kimhae city and Yangsan-Gun toward which heavy decentralization of manufacturing from the Metropolitan Pusan has been done. Both hard data and soft data were used as the basic data. Hard data are the statistical data in statistical yearbooks and firm list in directories. The former consists of the number of establishments and employees classified by product type, firm size and unit area. The latter consists of owner's names, addresses, employee number, products and headquarters of firms. Soft data are the results of the interviews with the 242 owners of firms in the four case study areas selected by Proportional Stratified Sampling Method. The major findings are as follows: 1. The spatial variations of manufacturing in the suburb was regularized in the latter half of 1970's. The primary processes to decentralize manufacturing from Metropolitan Pusan were the birth, relocation and establishment of branches of the firms. Among them the relocation of small outer-oriented single-location firms from Pusan was the most important. 2. The spatial variations undergoing spatial expansion of manufacturing distribution and increase of agglomeration degree of manufacturing, proceeded from the adjacents of Metropolitan Pusan to the outer areas along the main transportation route. 3. The main factors which caused manufacturing to decentralize from the Metropolitan Pusan were firm policy and land for this policy. The main locational factors which induced the decentralizing manufacturing into the suburb were land, market and transportation. 4. The strength of linkages with the outside of the study area is stronger than that of linkages with the inside. There is distance-decay-function in the strength of linkages with the outside, and linkages with short distant areas are stronger than those with long distant areas. 5. The ranges of spatial linkages in procurement of materials, in subcontraction and in marketing are wider than those in ordering. 6. The main factors which cause the formation of linkages are different by types of linkages: monopolistic and oligopolistic supply are important in procurement linkages; characteristics of products and the subsequent marketing difficulties, in subcontraction linkages; fluctuation, cost reduction, insufficient facility and characteristics of products, in ordering linkages; subcontract, characteristics of product and the subsequent marketing difficulties, in marketing linkages. 7. The changes of linkages owing to locational changes of firms were great, and were greater in long distant areas than in short distant areas. 8. The main factor influencing on the changes of linkages was the easiness in the transportation of goods, movement of labour and contacts with customers. In conclusion, some facts described above were proved to be consistent with the results of proceeding studies in the other areas: influence of relocation of decentralizing firms on the suburbanization; the factors of manufacturing decentralization; spatial characteristics of linkages; linkage changes owing to relocation of firms. Some were proved to be partly consistent: locational factors inducing decentralized manufacturing into the suburb were proved to be inconsistent. I think that the results of previous studies on the other areas can be applicable to the explanation on the decentralization of Metropolitan manufacturing from the viewpoint of the suburb. For the better explanation on the decentralization of Metropolitan manufacturing, more empirical case studies on the suburbanization of manufacturing are necessary.

• Journal of Korea Port Economic Association
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• v.23 no.4
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• pp.91-114
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• 2007

With rapid economic development in China, cargoes from and to China are growing significantly. The 3 Northeast Provinces of China(named Liaoniang, Jilin, Heilongjiang provinces), bordering the Korean Peninsular, is not exception in development of international trade. However long distance from the 3 Northeast Provinces to seaports generates huge transit time and costs because Dalian port is far away almost 1,000km from Jilin and Heiloongjiang Provinces. The new intermodal transport route through the port of Jarubino located in the Russian Far East is under way to reduce the costs incurred from inland transport. This paper investigates the competitiveness of the new international intermodal transport route from the 3 Northeast Provinces in terms of transit time and transport costs. According to the results of this research, The establishment of the new international intermodal transport with development of Jarubino port is expected to increase the competitiveness of trade cargoes from the 3 Northeast Provinces while Korea has a good opportunity to join the port development in the Russian Far East. Futhermore the port of Busan is also benefited the growing transit cargoes from the new intermodal transport route.

• Journal of Korean Society of Transportation
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• v.31 no.3
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• pp.19-32
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• 2013

The study aims to find the characteristics of children's crossing behavior on crosswalk in school zones. It considers accident occurrence and physical form of school zones. Seven elementary school zones were investigated. Using data collected by field observation and video recording, statistical analysis, CHAID algorithm analysis, and pattern analysis were performed. As a result, it was found that children's waiting, attention and distraction were related to the accident occurrence. While 69.1% children showed waiting-before-crossing behavior in low-accident occurrence crosswalk, 83.6% children showed non waiting-before-crossing behavior in high-accident occurrence crosswalk. Moreover, the ratio of waiting, attention behavior was found to be higher when the width of the crosswalk was wide and the distance from the school's entrance to the crosswalk was long. These research findings showed that children's behavior-oriented approach was required to improve safety in school zone.