• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.586-589
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• 2018

As the convergence of traffic system and Big-data technology, new convenient services which is helpful for drivers and pedestrian are appeared. Recently, the various researches about the traffic system, such as prediction of traffic jam and finding the shortest path, are studied. In this paper, we collect the data of taxi trips in Daegu City, and visualize them on the map of Daegu City. And then, we select specific sections of roads in the city, and by using the data of location and speed about taxis and the information of the road sections, calculate the traffic of that section and the average speed of cars on that section. As a result of this, we give help solving the problem of the specific road sections.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.233-236
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• 2010

This paper describes the packet traffic management of the Ubiquitous Healthcare System. In this system, ECG signal and accelerometer signal is transmitted from a wearable health shirt (WHS) to the base station. However, with the increment of users in this system, traffic over-load issue occurs. The main aim of this paper is to reduce the traffic over-load issue between sensor nodes by only transmitting the required signals to the base station when irregular activities are observed. In order to achieve this, in-network processing is adapted where the process of observation is conducted inside the sensor node of WHS. Results shows that irregular activities such as fall can be detected on real-time inside the sensor node and thus resolves traffic over-load issue.

• Journal of Advanced Navigation Technology
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• v.18 no.4
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• pp.278-287
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• 2014

ADS-B is a newly developed air surveillance technology to address the consistently increasing air traffic needs. ADS-B attracts attention for replacing or complementing a conventional radar since ADS-B can provide more accurate position information with a shorter interval when compared to the radar. However, as ADS-B uses wireless data links on exchanging information between an aircraft and a ground ADS-B system, and uses protocols without integrity support on exchanging information within the ground ADS-B system, a system which can monitor the operational status of an ADS-B system is essential. In this work, we design and implement an ADS-B monitoring system capable of displaying air traffic situation that can show the comprehensive air traffic situation while monitoring the operational status of the ADS-B system. The implemented ADS-B monitoring system has been verified with a configured ADS-B ground system by displaying ADS-B surveillance data, radar surveillance data, and flight information after receiving live surveillance data of in flight aircrafts, and virtual flight information data.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.2
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• pp.101-108
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• 2015

In this paper, a robust traffic light detection method is proposed by using vision sensor and DGPS(Difference Global Positioning System). The conventional vision-based detection methods are very sensitive to illumination change, for instance, low visibility at night time or highly reflection by bright light. To solve these limitations in visual sensor, DGPS is incorporated to determine the location and shape of traffic lights which are available from traffic light database. Furthermore the geometric relationship between traffic light and vision sensor is used to locate the traffic light in the image by using DGPS information. The empirical results show that the proposed method improves by 51% in detection rate for night time with marginal improvement in daytime environment.

• Journal of Advanced Navigation Technology
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• v.16 no.4
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• pp.611-618
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• 2012

ICAO has recommended the introduction of New CNS/ATM based on GNSS technologies and Data link communication to purpose increasing air traffic demand. The CNS/ATM is composed of communication, Navigation, Surveillance and Air Traffic Management. Cockpit Display Traffic Information(CDTI) that is equipment to share air traffic information to Pilot, Traffic Controller and ground vehicles has been built based on Automatic Dependent Surveillance-Broadcast(ADS-B) information in Surveillance field. This paper is research that what is the effect between pilot and controller through CDTI. Based on ATC communication between Pilot and Controller, We construct simulation environment and did a comparative analysis of it. according to result, We can verify that CDTI makes aircraft Call sign, Position, Altitude information read rate, and notice of air traffic information between Pilot and Controller more improve than ATC environment and Existing Radar System.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.05a
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• pp.199-202
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• 2009

The optimal path on real road network has been changed by traffic flow of roads frequently. Therefore a path finding system to find the optimal path on real network should consider traffic flow of roads that is changed on real time. The most of existing path finding methods do not consider traffic flow of roads and do not also perform efficiently if they use traffic information. In this paper, we propose an abstraction method of real road network based on the Terminal Based Navigation System (TBNS) with technique such as TPEG. TBNS can be able to provides quality of path better than before as using traffic information that is transferred by TPEG. The proposed method is to abstract real network as simple graph in order to use traffic information. It is composed boundary nodes based on real nodes, all boundary nodes that have the same of connection are merged together. The result of path finding on an abstract graph diminishes the search space.

• Journal of Navigation and Port Research
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• v.37 no.5
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• pp.447-452
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• 2013

Vessel traffic system uses multiple sea surveillance radars as a primary sensor to obtain maritime traffic information like as ship's position, speed, course. The systematic errors such as the range bias and the azimuth bias of the two-dimensional radar system can significantly degrade the accuracy of the radar image and target tracking information. Therefore, the systematic errors of the radar system should be corrected precisely in order to provide the accurate target information in the vessel traffic system. In this paper, it is proposed that the method compensates the range bias and the azimuth bias using AtoN information installed at VTS coverage. The radar measurement residual error model is derived from the standard error model of two-dimensional radar measurements and the position information of AtoN, and then the linear Kalman filter is designed for estimation of the systematic errors of the radar system. The proposed method is validated via Monte-Carlo runs. Also, the convergence characteristics of the designed filter and the accuracy of the systematic error estimates according to the number of AtoN information are analyzed.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.2
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• pp.135-144
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• 2003

Traffic performance in a microcellular system is much more affected by cell dwell time and channel holding time in each cell. Cell dwell time of a call is characterized by its mobility pattern, i.e., stochastic changes of moving speed and direction. Cell dwell time provides important information for other analyses on traffic performance such as channel holding time, handover rate, and the average number of handovers per call. In the next generation mobile communication system, the cell size is expected to be much smaller than that of current one to accommodate the increase of user demand and to achieve high bandwidth utilization. As the cell size gets small, traffic performance is much more affected by variable mobility of users, especially by that of pedestrians. In previous work, analytical models are based on simple probability models. They provide sufficient accuracy in a simple second-generation cellular system. However, the role of them is becoming invalid in a picocellular environment where there are rapid change of network traffic conditions and highly random mobility of pedestrians. Unlike in previous work, we propose an improved probability model evolved from so-called Random walk model in order to mathematically formulate variable mobility of pedestrians and analyze the traffic performance. With our model, we can figure out variable characteristics of pedestrian mobility with stochastic correlation. The above-mentioned traffic performance measures are analyzed using our model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.11
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• pp.4291-4310
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• 2015

This paper investigates the traffic offloading over unlicensed bands for two-tier multi-mode small cell networks. We formulate this problem as a Stackelberg game and apply a hierarchical learning framework to jointly maximize the utilities of both macro base station (MBS) and small base stations (SBSs). During the learning process, the MBS behaves as a leader and the SBSs are followers. A pricing mechanism is adopt by MBS and the price information is broadcasted to all SBSs by MBS firstly, then each SBS competes with other SBSs and takes its best response strategies to appropriately allocate the traffic load in licensed and unlicensed band in the sequel, taking the traffic flow payment charged by MBS into consideration. Then, we present a hierarchical Q-learning algorithm (HQL) to discover the Stackelberg equilibrium. Additionally, if some extra information can be obtained via feedback, we propose an improved hierarchical Q-learning algorithm (IHQL) to speed up the SBSs' learning process. Last but not the least, the convergence performance of the proposed two algorithms is analyzed. Numerical experiments are presented to validate the proposed schemes and show the effectiveness.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.12
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• pp.3154-3164
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• 1996

A major concern in a cellular mobile communication system is how to efficiently utilize the limited amount of frequencies. Various channel assignment methods and traffic sharing schemes have been proposed to improve system performance. However, these approaches suffer from complicated software and hardware requirements due to increased amount of traffic control In this paper, we propose a new method for improving system performance by controlling the powers of the set-up and voice channels of each cell site. We first show that the average number of blocked calls in a system is minimized when the traffic reates are made identical for all cell sites in a system. This result, together with the relationship between the channel powers and the service area, is used to determine the appropriate channel powers of each cell site. We also determine the upper limit on the channel power of each cell site considering co-channel interference and numerically show that the proposed method is effective in reducing the number of blocked calls without an excessive increase in the amount of system control.