• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1D
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• pp.45-51
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• 2010

Traffic volume is essential data for traffic control or maintenance and rehabilitation planning. The volume especially with respect to the type of vehicles can facilitate to those road operations. In this research, a method for vehicle classification was developed using skewed sensors which can generate traffic signatures. In order to characterize vehicle types, the method investigates whether the second axle of each vehicle consists of dual tires. The presence of dual tire is determined by the discriminate function obtained from discriminant analysis. The validation using 1,878 vehicles recorded from a highway using a CCTV camera indicated significantly accurate results: 96.92% for class 1, 82.91% for class 3 and 79.13% for class 4.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.543-546
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• 1996

Recently, some research has been done to analyze the asymptotic behavior of queue length distribution in ATM (Asynchronous Transfer Mode) multiplexer. In this paper, we relate this asymptotic behavior with the asymptotic behavior of decreasing cell loss probability when the buffer capacity is increased. We find with reasonable assumptions that the asymptotic rate of queue length distribution is the same as that of decreasing cell loss probability. Even under different priority control schemes and traffic classes, we find that this asymptotic rate of the individual cell loss probability of each traffic class does not change. As a consequence, we propose the upper bound of cell loss probability of each traffic class when a priority control scheme is employed. This bound is computationally feasible in a real-time. The numerical examples will be provided to validate this finding.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.21 no.4
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• pp.939-951
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• 1996

The previous study of virtual path design for one traffic class with ATM DCS only should be generalized to that for the multiple traffic class cases of being given neither virtual path candidate set nor end nodes o each virtual path. In this paper, a design model of virtual paths for the general case with multiple traffic classes is suggested. The model is represented as an optimization rpoblem with a special structure. It is solved by SQA algorithm, which is developed by authors in [3, 4]. The model and the algorithm are applied to a numerical example, and results are shown.

• Journal of Korea Planning Association
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• v.54 no.1
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• pp.52-66
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• 2019

Travel is a factor that stimulates the vitality of the urban and is widely used as an indicator of sustainable growth of the region. In Korea, however, no studies has been made to predict changes in traffic and calculate the accessibility of the region by comprehensively considering the socio-economic conditions of the travelers. The purpose of this study is to classify commuters according to the household income and to analyse the traffic characteristics of each class. The analysis results are aggregated into two. First, the analysis of study found different transport characteristics for different income classes. This is the result that underpins the argument of a previous study that suggested that a discriminatory approach is necessary for each income in determining the accessibility of the region. Second, this study calculated utility values differently for each income class based on the transit time and cost required between each zone. Through these measures, transport characteristics were analyzed by income class using indicators that considered transportation infrastructure, and socio-economic conditions of the travelers. This study is meaningful in that it provided the basis for calculating the accessibility that could take into account the activities of the housing consumers in establishing domestic housing policies.

• Journal of applied mathematics & informatics
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• v.8 no.3
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• pp.1035-1045
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• 2001

We present two decomposition approximations for the mean sojourn times in open single class queing networks. If there is a single bottleneck station, the approximations are asymptotically exact in both light and heavy traffic. When applied to a Jackson network or an M/G/1 queue, these approximations are exact for all values of the traffic intensity.

• Journal of Preventive Medicine and Public Health
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• v.40 no.1
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• pp.7-15
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• 2007

Objectives : This study investigated the relationship of occupational class and educational background with proportional mortality ratios in Korea. Methods : Mortality was investigated using the entire registered death data from 1993 to 2004, obtained from the Korean National Statistics Office. Proportional mortality ratios (PMRs) for specific diseases were calculated according to the occupational class and educational background of men aged 20-64. Results : Manual workers were found to have higher PMRs for liver disease and traffic accidents, as did the lower educated group. Especially, this study showed trends of an increasing of the wide gap between lower and higher socioeconomic stati for liver disease, traffic accidents, diabetes mellitus and cerebral vascular disease. The mortality for cerebrovascular disease, diabetes mellitus, heart disease, traffic accident and liver disease showed increasing trends according to the calendar year for the lower than the higher social class. Conclusions : The specific conditions that had higher PMRs in the Korean lower social class were liver disease and traffic accidents. Especially, there was an increasing trend for a widening of the gap between manual and non-manual groups in relation to mortality from liver disease, diabetes mellitus and traffic accidents.

• Journal of Korean Society of Transportation
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• v.22 no.5
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• pp.123-137
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• 2004

The study on traffic assignment is actively being performed which reflect networks status using time. Its background is increasing social needs to use traffic assignment models in not only hardware area of road network plan but also software area of traffic management or control. In addition, multi-class traffic assignment model is receiving study in order to fill a gap between theory and practice of traffic assignment model. This model is made up of two, one of which is multi-driver class and the other multi-vehicle class. The latter is the more realistic because it can be combined with dynamic model. On this background, this study is to build multidynamic model combining the above-mentioned two areas. This has been a theoretic pillar of ITS in which dynamic user equilibrium assignment model is now made an issue, therefore more realistic dynamic model is expected to be built by combining it with multi-class model. In case of multi-vehicle, FIFO would be violated which is necessary to build the dynamic assignment model. This means that it is impossible to build multi-vehicle dynamic model with the existing dynamic assignment modelling method built under the conditions of FIFO. This study builds dynamic network model which could relieve the FIFO conditions. At the same time, simulation method, one of the existing network loading method, is modified to be applied to this study. Also, as a solution(algorithm) area, time dependent shortest path algorithm which has been modified from existing shortest path algorithm and the existing MSA modified algorithm are built. The convergence of the algorithm is examined which is built by calculating dynamic user equilibrium solution adopting the model and algorithm and grid network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.8B
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• pp.707-715
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• 2003

In this paper, we propose a new MAC(Medium Access Control) protocol using Movable-boundary, which tries to guarantee Qos for multimedia traffic in the slotted CDMA system. In this scheme, the traffic scheduler assigns channel resource according to the packet priority per service class and adapts the Movable-boundary concept in which the minimum resource is assigned to each traffic class; the remaining resource if it is available can be assigned dynamically according to the temporal demand of other traffic classes. For performance analysis, we performed computer simulations to obtain throughput and packet loss rate and compared the results with Fixed-boundary system. We observed that the error rate of voice traffic could be maintained below a prescribed value while bursty traffic such as video source shares the same channel. In comparison with Fixed-boundary scheme, our protocol exhibits better throughput and packet loss rate performance.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.2
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• pp.191-195
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• 2008

This paper proposes a technique for improving IEEE 802.11e EDCA's performance by dynamically adjusting each class's contention window size based on each class's traffic amount. For providing differentiated service differently from 802.11, 802.11e EDCA maintains four classes each of which specifies different static minimum and maximum contention window sizes. Since the initial window sites significantly affect the 802.11e performance, several window adjustment schemes have been proposed. One of the schemes known as CWminAS (CWmin Adaptation Scheme) dynamically and synchronously determines the four windows' site based on the periodically measured collision rate. This method, however, can lower the send probability of high priority classes since it can't differentiate their collisions from those of low priority classes, leading to the channel underutilization. For solving this problem, we propose ACATICT(Adaptive Contention-window Adjustment Technique based on Individual Class Traffic) algorithm which adapts each class window size based on each individual collision rate rather than one average collision rate. Our simulation experiments show that ACATICT achieves better utilization by around 10% at maximum.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.6
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• pp.96-106
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• 2020

To solve the limitation of traffic monitoring that occur from embedded sensor such as loop and piezo sensors, the thermal imaging camera was installed on the roadside. As the length of Class 1(passenger car) is getting longer, it is becoming difficult to classify from Class 3(2-axle truck) by using an embedded sensor. The collected images were labeled to generate training data. A total of 17,536 vehicle images (640x480 pixels) training data were produced. CNN (Convolutional Neural Network) was used to achieve vehicle classification based on thermal image. Based on the limited data volume and quality, a classification accuracy of 97.7% was achieved. It shows the possibility of traffic monitoring system based on AI. If more learning data is collected in the future, 12-class classification will be possible. Also, AI-based traffic monitoring will be able to classify not only 12-class, but also new various class such as eco-friendly vehicles, vehicle in violation, motorcycles, etc. Which can be used as statistical data for national policy, research, and industry.