• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2012.06a
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• pp.172-174
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• 2012

The maritime traffic system research has been studied for the safety and efficiency of the Marine Navigation. In order to evaluate the maritime traffic system, the vessel traffic observation is playing important roll. Recently, the way of collecting the vessel traffic information has been become fixed by using the radar, the AIS and the visual observations. However, it is still difficult to get the information about ships without the AIS. In this paper, the past vessel traffic observation results are shown. From those data and introducing the way of Japanese traffic survey, the recent matters of the vessel traffic observation are discussed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.1
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• pp.151-156
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• 2006

Accurate vessel traffic observation is indispensable to carry out vessel traffic management, design of vessel traffic route, planning of port construction, etc. In order to observe the vessel traffic accurately without many efforts such as the use of a ship or car equipped with special radar observation system and the preparation of observation staff, the authors have been developing completely automated remote radar/AIS network system covering the main traffic area in Tokyo Bay. The composite radar image observed at Yokosuka and Kawasaki radar stations with AIS information can be seen on web site of Internet. In addition to the development of radar/AIS observation system, the software to analyze observed vessel traffic flow has been developed. This software has various functions such as automatic tracking of ship's positions, automatic estimation of ship's size, automatic integration of radar image and AIS data, animation of ships' movements, extraction of dangerous ship encounters, etc. The configuration and functions of the developed remote radar/AIS network system are shown first in this paper. Then various functions of the software to analyze vessel traffic are introduced, and some analyzed results on the vessel traffic in Tokyo Bay are described demonstrating the effectiveness of the developed system.

• Journal of Navigation and Port Research
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• v.29 no.4
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• pp.313-318
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• 2005

Usually marine traffic survey has been conducted by some methods like an ocular observation using portable RADAR, a questionnaire, etc. But these should have expended a lot of manpower and expenses. In this paper, we have developed new observation module which could capture the RADAR image using PC camera simply, and allowed as to track targets on the PC monitor directly. And it has been programmed to make a database of RADAR image, target's track and information, and analyze the marine traffic tendency in various ways like vessel number crossed over gate line, vessel's velocity distribution in gate line, traffic density distribution, etc. We have confirmed that this module could observe and analyze the marine traffic efficiently and economically through several on-the-spot experiments.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.08a
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• pp.208-216
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• 2004

Since 2000, the authors have been developing remote radar network system to observe the vessel traffic in Tokyo Bay. In December 2002, the first operational remote radar station was set at the National Defense Academy in Yokosuka, and vessel traffic observation was started. However, it was impossible to perform accurate observation in the northern part of Tokyo Bay by this Yokosuka radar station only. In September 2003, the second remote radar station and AIS receiving station were installed at Higashi Ogishima in Kawasaki. This second radar enabled us to carry out accurate observation in that area. Both radars can be remotely controlled from the monitoring station in Tokyo University of Marine Science and Technology. On September 30 and October 1,2003, the vessel traffic observation was carried out using both radars. Combining radar images observed by both radars, the ships' tracks were taken and the dangerous ships were extracted by using SJ value and Bumper Model. The time changes of dangerous ship density in some areas in Tokyo Bay and utilization ratio of the traffic routes were also investigated. In addition, analyzing the AIS date received at Kawasaki station, the positions and speed vectors of the ships equipped with AIS were shown.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.4
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• pp.397-402
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• 2015

This study is to compare variation indexes by monthly, weekly and hourly using AIS data, which was collected for 365 days from January 1st to December 31st, 2013 at Mokpo Port and then, computed the maximum standard error by observation days. The comparison of monthly variation indexes showed that the monthly variation indexes for September and February were 1.11 and 0.84, respectively, in turn revealing that the maritime traffic in September was about 32.1 % larger than February. Also, the daily variation indexes for Tuesday and Sunday were 1.05 and 0.92, respectively, in turn revealing that the maritime traffic in Tuesday was about 14.1 % larger than Sunday. When the maritime traffic investigation is executed for at least 1 week in consideration of the daily variation index, it is possible to reduce the maximum standard error rate to be within 21 %. Therefore, if the maritime traffic investigation is made in the month and week with low maritime traffic, each variation index should be applied to reflect the actual maritime traffic.

• The Korean Journal of Applied Statistics
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• v.25 no.4
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• pp.621-632
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• 2012

Recurrent event data can be easily found in longitudinal studies such as clinical trials, reliability fields, and the social sciences; however, there are a few observations that disappear temporarily in sight during the follow-up and then suddenly reappear without notice like the Young Traffic Offenders Program(YTOP) data collected by Farmer et al. (2000). In this article we focused on inference for a cumulative mean function of the recurrent event data with these incomplete observation gaps. Defining a corresponding risk set would be easily accomplished if we know the exact intervals where the observation gaps occur. However, when they are incomplete (if their starting times are known but their terminating times are unknown) we need to estimate a distribution function for the terminating times of the observation gaps. To accomplish this, we treated them as interval-censored and then estimated their distribution using the EM algorithm proposed by Turnbull (1976). We proposed a nonparametric estimator for the cumulative mean function and also a nonparametric test to compare the cumulative mean functions of two groups. Through simulation we investigated the finite-sample performance of the proposed estimator and proposed test. Finally, we applied the proposed methods to YTOP data.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.111-119
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• 2013

PURPOSES: Though the situation that the roundabouts are actively constructed, researches on the effect of the roundabouts focus mainly on the analysis of the expected effects of using only traffic simulation on the operation. Considering such problems, this study is conducted to analyze the effects of the various aspects based on field observation studies. METHODS: This study evaluated and analyzed the effects from the aspects of traffic operation, traffic safety, and traffic behavior by performing field observation studies with six roundabouts with/without signal controls on the pilot project areas for the roundabouts installed in 2010. RESULTS: Through the study results, it was found that the average travel time decreases by 14.7% and 2.4% on the signalized intersections and unsignalized intersections, respectively. The average travel speed increases by 9.7 and 5.8km/h on the roundabouts with/without signal lights. Regarding traffic safety, the speed deviation among individual vehicles decreases by approximately 18.4 to 32.7km/h, thus confirming the safety effects. As the decrease of the number of conflicts, it might be explained that car crashes and collision with pedestrians decreased by 62.2% and 66.7%. Also the result shows that the lowest point of speed in roundabouts appears near the yield line on the entry area on the roundabouts. When passing through the roundabouts, vehicles enter at a speed of 20-30km/h, which is the design speed of the circulatory lane and drive out the roundabout with a higher speed than the entry speed. CONCLUSIONS: When a roundabout is introduced at the intersections below certain traffic volume there are effects of traffic operation, traffic safety, and traffic behavior.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.9
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• pp.1139-1145
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• 2019

In order to efficiently use defined satellite network resources, it is a priority to understand the performance and usage of the network. In this paper, in order to analyze the operational efficiency and stability of the system in the satellite communication system operated by K-water flood forecast and alarm network, FTP and ping testing and network traffic analysis methods of measuring download and upload speed between central and observational countries were introduced. As a result of measuring the transmission speed by the introduced test method, the effects of TCP accelerators have been improved by 120% upon download from the observational station. Through the performance test and traffic analysis of the satellite hydrologic observation system introduced, environmental improvement and improvement points of the satellite communication system were derived so that the operational efficiency and stability of the communication network could be expected.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.502-506
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• 2007

Railway accidents/incidents occur because of many reasons. Human error by the railway staff or personnel takes a major part of those reasons. In order to reduce and prevent railway accidents/incidents, appropriate measures should be developed to remove root causes induced in human error. A systematic study for analysing causes of human errors and for developing an effective management is necessary. Detailed analysis of the railway traffic signaller's tasks should be preferentially performed for this purpose. This paper introduces the results of analysis for the types and characteristics of the railway traffic signaller's tasks. As a result of the analysis, the railway traffic signaller's tasks can be decomposed into 24 tasks in total, and also be divided into the general task and the emergency task. The railway traffic signaller's tasks are characterized to require continual confirmation and observation activities, and sometimes immediate decision and action.

• Communications for Statistical Applications and Methods
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• v.10 no.3
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• pp.795-804
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• 2003

In this article, a tomography for the estimation of the origin-destination(OD) traffic intensities in dynamic routing network is considered. Vardi(1996)'s approach based on fixed route is not directly applicable to dynamic routing protocols, which arises from the fact that we cannot access the route at every observation time. While it uses link-wise traffics as the observations, the proposed method considers the triple of ingress/outgress/relayed traffics data at each node so that we can transform the problem into a routing-independent tomography. An EM algorithm for implementation and some simulated experiments are provided.