• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.10
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• pp.4754-4773
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• 2018

In sensor medium access control (SMAC) protocol, sensor nodes can only access the channel in the scheduling and listening period. However, this fixed working method may generate data latency and high conflict. To solve those problems, scheduling duty in the original SMAC protocol is divided into multiple small scheduling duties (micro duty MD). By applying different micro-dispersed contention channel, sensor nodes can reduce the collision probability of the data and thereby save energy. Based on the given micro-duty, this paper presents an adaptive duty cycle (DC) and back-off algorithm, aiming at detecting the fixed duty cycle in SMAC protocol. According to the given buffer queue length, sensor nodes dynamically change the duty cycle. In the context of low duty cycle and low flow, fair binary exponential back-off (F-BEB) algorithm is applied to reduce data latency. In the context of high duty cycle and high flow, capture avoidance binary exponential back-off (CA-BEB) algorithm is used to further reduce the conflict probability for saving energy consumption. Based on the above two contexts, we propose an improved SMAC protocol, micro duty adaptive SMAC protocol (MDA-SMAC). Comparing the performance between MDA-SMAC protocol and SMAC protocol on the NS-2 simulation platform, the results show that, MDA-SMAC protocol performs better in terms of energy consumption, latency and effective throughput than SMAC protocol, especially in the condition of more crowded network traffic and more sensor nodes.

• Journal of KIISE:Information Networking
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• v.33 no.3
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• pp.201-217
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• 2006

In this paper, we collected the physical traces from high speed Internet backbone traffic and analyze the various characteristics of the underlying packet traces. Particularly, our work is focused on analyzing the characteristics of an anomalous traffic. It is found that in our data, the anomalous traffic is caused by UDP session traffic and we determined that it was one of the Denial of Service attacks. In this work, we adopted the unsupervised machine learning algorithm to classify the network flows. We apply the k-means clustering algorithm to train the learner. Via the Cramer-Yon-Misses test, we confirmed that the proposed classification method which is able to detect anomalous traffic within 1 second can accurately predict the class of a flow and can be effectively used in determining the anomalous flows.

• The Journal of Pediatrics of Korean Medicine
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• v.26 no.2
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• pp.35-46
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• 2012

Objectives The purpose of this study was to find out the characteristics of children patients who had been treated in the Oriental Medical Hospital due to traffic accidents. Methods The study was carried out with 121 children patients who visited the Oriental Medical Hospital from April 2011 to March 2012 and was analyzed by reviewing the patients' charts. Results In the distribution of sex the ratio between boys and girls were similar, but regarding the age, 0~6 year-old group was more than that of 7~15 year-old group. In the traffic accident patterns, 87.6% of the entire children patients were injured by car crash. The highest type in the collision between cars was rear-ending impact. The most patients (48.8%) visited our hospital for oriental medical treatment in less than 3 days after the traffic accident. The number of the first visitors in the Oriental Medical Hospital were 77 (63.6%) and those who visited other western hospitals before and were 44 (36.4%). The most frequent duration of admission and treatment in OPD was less than 7 days. Sleeping disorders (37.1%) were diagnosed the highest in 0~6 year-old group and C-spine sprain (49.0%) was diagnosed the highest at 0~7 years-old group. Herb medications were prescribed to relieve anxiety for 0~6 year-old group and for 7~15 year-old group, those were prescribed to activate blood eliminating phlegm and to normalize Qi flow. The highest effective treatment period was less than 7 days. Conclusions This data suggested that the oriental medical care could be more effective in treating children victims of traffic accidents by confirming many different symptoms depending on the age.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.1
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• pp.69-74
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• 2021

Internet access is also increasing as online activities increase due to the influence of Corona 19. However, network attacks are also diversifying by malicious users, and DDoS among the attacks are increasing year by year. These attacks are detected by intrusion detection systems and can be prevented at an early stage. Various data sets are used to verify intrusion detection algorithms, but in this paper, CICIDS2017, the latest traffic, is used. DDoS attack traffic was analyzed using the decision tree. In this paper, we analyzed the traffic by using the decision tree. Through the analysis, a decisive feature was found, and the accuracy of the decisive feature was confirmed by proceeding the decision tree to prove the accuracy of detection. And the contents of false positive and false negative traffic were analyzed. As a result, learning the feature and the two features showed that the accuracy was 98% and 99.8% respectively.

• Journal of Korean Society of Transportation
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• v.33 no.1
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• pp.90-99
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• 2015

The climate of Korea has clear rainy and dry season due to seasonal wind. In general, The rainy season in Korea is from early summer through to early fall. And precipitation accounted for more than half of the total annual rainfall in this period. This study is aiming to analysis of variation in saturation flow rate at signalized intersection during rainfall. The range of spatial is urban signalized intersections in Seoul and temporal is rainfall or ideal condition in daylight. Traffic data are collected through CCTV of Seoul Metropolitan Police Agency, and on-site video recordings directly. Weather condition data are collected from the Korea Meteorological Administration. In addition, the value of saturation headway and saturation flow rate, in rainfall condition, are derived through video frame analysis. As a results of analysis, decrease of saturation flow rate and increase of saturation headway during rainfall were confirmed by comparison with non-rainfall. The higher rainfall rate is, the more decreased saturation flow rate at the intersections. Rainfall rate is divided three area by the results of statistical test, and saturation flow rate decrease 7%, 17%, 21%, respectively.

• Journal of Korean Society of Transportation
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• v.27 no.4
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• pp.115-126
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• 2009

The lane-change behavior usually consists of discretionary lane-change and mandatory lane-change types. For the first type, drivers change lanes selectively to maintain their own driving condition and the second type is the case that the drivers must change the current lane, which can occur in recurrent congestion sections like merging and weaving sections. The mandatory lane-change behavior have a great effect on the operation condition of freeway. In this paper, we first generate data such as traffic volumes, speeds, densities, and the number of lane-change within the merging and weaving sections using the data of individual vehicle collected from time-lapse aerial photography. And then, the data is divided into the stable and congested flow by analyzing the speed variation pattern of individual vehicles. In addition, the number of lane-changing from ramp to mainline within every 30-meter interval is investigated before and after traffic congestion at study sites and the distribution of lane-changing at each 30-meter point is analyzed to identify the variation of lane-changing ratio depending on the stable and congested flows. To recognize the effect of mainline flow influenced by ramp flow, this study also analyzes the characteristics of the lane-changing distributions within the lanes of mainline. The purpose of this paper is to present the basic theory to be used in developing a lane-changing model at the merging and weaving sections on freeways.

• International Journal of Highway Engineering
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• v.20 no.3
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• pp.85-92
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• 2018

PURPOSES : In this study, analyze the characteristics of IOC indicator 'threshold' which is needed when evaluating the traffic signal operation status with ESPRESSO in various grade road traffic environment of Seoul metropolitan city and derive suggested value to use in field practice. METHODS : Using the computerized database program (Postgresql), we extracted data with regional characteristics (Arterial, Collector road) and temporal characteristics (peak hour, non-peak hour). Analysis of variance and Duncan's validation were performed using statistical analysis program (SPSS) to confirm whether the extracted data contains statistical significance. RESULTS : The analysis period of the main and secondary arterial roads was confirmed to be suitable from 14 days to 60 days. For the arterial, it is suggested to use 20 km/h as the critical speed for PM peak hour and weekly non peak hour. It is suggested to use 25 km/h as the critical speed for AM peak hour and night non peak hour. As for the collector road, it is suggested to use 20 km/h as the critical speed for PM peak hour and weekly non peak hour. It is suggested to use 30 km/h as the critical speed for AM peak hour and night non peak hour. CONCLUSIONS : It is meaningful from a methodological point of view that it is possible to make a reasonable comparative analysis on the signal intersection pre-post analysis when the signal operation DB is renewed by breaking the existing traffic signal operation evaluation method.

• Journal of Korean Society of Transportation
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• v.29 no.3
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• pp.73-82
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• 2011

Recent advancement in traffic surveillance systems has allowed the researchers to obtain more detailed vehicular movement such as individual vehicle trajectory data. Understanding the characteristics of interactions between leading and following vehicles in the traffic flow stream is a backbone for designing and evaluating more sophisticated traffic and vehicle control strategies. This study proposes a methodology for estimating rear-end crash potential, as a probabilistic measure, in real-time based on the analysis of vehicular movements. The methodology presented in this study consists of three components. The first predicts vehicle position and speed every second using a Kalman filtering technique. The second estimates the probability for the vehicle's trajectory to belong to either 'changing lane' or 'going straight'. A binary logistic regression (BLR) is used to model the lane-changing decision of the subject vehicle. The other component calculates crash probability by employing an exponential decay function that uses time-to-collision (TTC) between the subject vehicle and the front vehicle. The result of this study is expected to be adapted in developing traffic control and information systems, in particular, for crash prevention.

• Journal of Korean Society for Atmospheric Environment
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• v.18 no.E2
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• pp.69-77
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• 2002

The nationwide NO$_2$monitoring program has been carried out using the passive sampler in Korea since 1993. During the sixteenth periods of measurement, total 26,474 sites of data were collected through eight years. In this paper, the roadside NO$_2$concentration of six major cities were analyzed. As results, the most frequent NO$_2$concentration of Seoul, Incheon, and Daegu ranged from 40 to 60 ppb, and that of Pusan, Kwanju, and Daejeon was from 20 to 40 ppd. Despite that the automobile number of Incheon was less than that of Daegu and Pusan, the exceedence rate of Korean national ambient air quality standard and ninetieth percentile concentration of Incheon were almost the same level as Seoul. In addition, the mean and standard deviation of roadside NO$_2$concentration of Seoul and Incheon was also appeared to be higher than that of other cities. These results indicates that NO$_2$concentration on roadside was affected by the traffic volumes and the traffic flow conditions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.87-92
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• 2013

This study is to analyze the impacts of different High-Pass lane speed limits. Paramics, microscopic simulation software, was used to perform microscopic simulations. For the simulations, Incheon toll gate traffic count data was used. The Paramics simulation results show that higher High-Pass speed limit (70Km/h) produced better traffic flow condition and less air pollution cost compared to existing High-Pass speed limit (30Km/h).