• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.5
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• pp.26-37
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• 2009

This paper suggests a sensor's placement method for detecting the dilemma zone problem when real-time driver's safety service is provided at signalized intersections by multiple pointed traffic sensors using USN environments. For detecting the dangerous situations from vehicles accelerating through yellow intervals, red-light running and stopping abruptly like as dilemma zone problem, VISSIM(microscopic, behavior-based multi-purpose traffic simulation program) is used to perform a real-time multiple detection situation by changing the input data like as various inflow-volume, design speed change, driver perception and response time. As a result, the optimal interval of traffic sensors is 20~27m, and the initialized sensor location from stop-line is different according to road design speed. Moreover, the pattern of detection about dilemma zone is also different according to inflow-volumes. This paper shows that the method is useful to evaluate the sensor's placement problem based on micro-simulation and the results can be used as the basic research for USN services.

• Journal of Korean Society for Geospatial Information Science
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• v.10 no.1 s.19
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• pp.59-66
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• 2002

The rapid change of industrial structure causes to increase distribution cost and requires necessity of physical distribution system urgently. Traffic situation is getting extremely worse and traffic jam has led to increasing expense of physical distribution delivery which dominates 20% of distribution cost. In this situation, the shortest and most suitable path search system is required by modern people who must waste a lot of time for moving with a car or on the street as well as many companies. for these reasons, we developed the shortest-path-searching system applying the dijkstra algorithm which is one of the effective shortest path algorithm to GIS, and it was constructed by considering realistic urban traffic and the pattern of street in a physical situation. Also, this system was developed to be updated weight data automatically, considering the dynamic change of traffic situation such as a traffic information service which will be served in real time. Finally, we designed this system to serve on web by using MapObjects IMS.

• International Journal of Highway Engineering
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• v.9 no.4
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• pp.129-134
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• 2007

In general, based on traffic data in a ideal traffic condition, BPR cost function is used to a variety of transportation policies. However, Some researchers have reported that BRP cost function is not appropriate for analyzing traffic pattern as well as forecasting future demand.(Spiess, 1989 ; Singh, 1999) Therefore, in this paper to solve this problem, a methodology based on data through Micro traffic Simulator Based(MSB) is developed. As a result following outputs are obtained ; (1) presenting a methodology to develop a travel cost function through VISSIM in order to assess transportation policies and (2) developing BRP cost function and MSB cost function from data analysis through VISSIM and verifying availability of MSB function by comparative analysis.

• Journal of Korea Port Economic Association
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• v.22 no.3
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• pp.79-96
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• 2006

In this paper, using the gravity model, I examined that the port traffic in the port of Pusan have been influenced by GDP of South Korea, GDP of trading countries, an agreement on maritime transport, maritime transport charge and the local economic integration, etc. In view of the policy implication based on the result of analysis by the gravity model, the port traffic and the transshipment in the port of Pusan is positively influenced by GDP of South Korea, GDP of trading countries and countries on the way of main sea route(LINE). But it is negatively influenced by maritime transport charge. Especially, when a maritime transport charge goes up 1 percentage point, it is estimated that a transshipment decreases about 0.586-0.895 percentage point. So, a maritime transport charge was found to have more effect on a transshipment than a port traffic(except transshipment).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.762-777
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• 2014

With the increasing usage of cloud applications such as MapReduce and social networking, the amount of data traffic in data center networks continues to grow. Moreover, these appli-cations follow the incast traffic pattern, where a large burst of traffic sent by a number of senders, accumulates simultaneously at the shallow-buffered data center switches. This causes severe packet losses. The currently deployed TCP is custom-tailored for the wide-area Internet. This causes cloud applications to suffer long completion times towing to the packet losses, and hence, results in a poor quality of service. An Explicit Congestion Notification (ECN)-based approach is an attractive solution that conservatively adjusts to the network congestion in advance. This legacy approach, however, lacks scalability in terms of the number of flows. In this paper, we reveal the primary cause of the scalability issue through analysis, and propose a new congestion-control algorithm called FaST. FaST employs a novel, virtual congestion window to conduct fine-grained congestion control that results in improved scalability. Fur-thermore, FaST is easy to deploy since it requires only a few software modifications at the server-side. Through ns-3 simulations, we show that FaST improves the scalability of data center networks compared with the existing approaches.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.105-114
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• 1999

The pattern of traffic streams in residential streets is different from the ordinary roads separated by pedestrian and car lanes. Such fact makes it difficult to evaluate the new counter-measures with existing indices and methods. In this study, a unified, consistent new method is introduced as Time-Space Occupancy (TSO) concept. An application of TSO concept will suggest a TSO exposure volume index which can show the decree of danger in residential streets where vehicles, pedestrian and other traffic streams are interacted. The validity of TSO exposure volume index will be verified through the survey conducted in Seoul and the subjects will be the residents who live at various kinds of residential streets.

• Journal of the military operations research society of Korea
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• v.2 no.1
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• pp.177-184
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• 1976

As the organizational size of a military service or business increases and its management becomes complex, the success in its management depends less on static type of management but more on careful, dynamic type of management. In this thesis, an operations research technique is applied to the problems of determining optimal air traffic control rule and of optimal capacity of air base for a military air base. An airport runway is regarded as the service facility in a queueing mechanism, used by landing, low approach, and departing aircraft. The usual order of service gives priority different classes of aircraft such as landings, departures, and low approaches; here service disciplines are considered assigning priorities to different classes of aricraft grouped according to required runway time. Several such priority rules are compared by means of a steady-state queueing model with non-preemptive priorities. From the survey conducted for the thesis development, it was found that the flight pattern such as departure, law approach, and landing within a control zone, follows a Poisson distribution and the service time follows an Erlang distribution. In the problem of choosing the optimal air traffic control rule, the control rule of giving service priority to the aircraft with a minimum average waiting cost, regardless of flight patterns, was found to be the optimal one. Through a simulation with data collected at K-O O Air Base, the optimal take-off interval and the optimal capacity of aircraft to be employed were determined.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.2B
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• pp.111-119
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• 2011

As Green-IT has attracted a lot of attention in recent years, many researches have been interested in reducing the energy consumption of network equipments. In this paper, we analyze the energy saving ratio and delay performance according to various traffic patterns and burst assemble algorithms in OBS network with sleeping mode. To do this, we design the traffic generators, which are based on exponential distribution and Pareto distribution, and the router model, which has the time based and length based burst assemble algorithms by using OPNET modeler. Through OPNET simulator, we evaluate the energy saving performance in terms of the sleeping time, the number of transitions and packet delay.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.74-77
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• 2000

Since the opening of the mobile telecommunications market to new entrants in 1996, the mobile telecommunications industry in Korea has transformed into a severely competitive market. Although there are numerous methods to evaluate the effects of the competition policy, the most relevant would be to measure the decreased degree of mobile service tariff. Also, after the Introduction of competition in the market, most carriers launched a variety of new tariff plans, which would satisfy the users′ traffic volume and pattern. Therefore, it is necessary to develop a "mobile tariff index" that would collectively consider all the various tariff plans. This paper aims to develop a mobile tariff Index that would accommodate all the various tariff plans provided by mobile carriers. To develop this mobile tariff index, mobile user′s will first be classified by their traffic volume, and then calculate the average tariffs per minute of each group of users, and lastly weight-average those tariffs per minute. And finally, this paper shows the mobile tariff index by considering those averaged tariffs and the carriers′ market shares to reflect the contribution of individual carriers and the users′ traffic volume.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.11
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• pp.1017-1021
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• 2013

The traffic signal has been widely used in the transport system with a fixed time interval currently. This kind of setting time was determined based on experience for vehicles to generate a waiting time while allowing pedestrians crossing the street. However, this strict setting causes inefficient problems in terms of economic and safety crossing. In this research, we propose a monitoring algorithm to detect, track and check pedestrian crossing the crosswalk by the patterns of behavior. This monitoring system ensures the safety for pedestrian and keeps the traffic flow in efficient. In this algorithm, pedestrians are detected by using HOG feature which is robust to illumination changes in outdoor environment. According to a complex computation, the parallel process with the GPU as well as CPU is adopted for real-time processing. Therefore, pedestrians are tracked by the relationship of hue channel in image sequence according to the predefined pedestrian zone. Finally, the system checks the pedestrians' crossing on the crosswalk by its HOG based behavior patterns. In experiments, the parallel processing by both GPU and CPU was performed so that the result reaches 16 FPS (Frame Per Second). The accuracy of detection and tracking was 93.7% and 91.2%, respectively.