• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.3
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• pp.236-242
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• 2002

This paper presents some advanced and supplemental methods to enhance the accuracy In case of calculating geometric divergence attenuation, attenuation by multiple screening structures, ground attenuation at unflat surfaces of sound during propagation outdoors by the methods specified in ISO 9613-2. Moreover, a calculation method for considering short-term wind effect, specified in ASJ Model-1998, is also introduced. To verity the accuracy of adopted methods, we have carried out highway traffic noise prediction and measurement at tile twelve locations appearing representative road shapes and structures, such as flat, retained cut, elevated, barrier-constructed roads. From the results, we have confirmed the predicted results show good correspondence with the measured at direct, diffracted and reflected sound fields within 30 m from the center of near side lane.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.1
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• pp.22-33
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• 2020

Due to recent increased air traffic,, air traffic controllers in charge of en-route and approach control have faced huge increase in both workload and its intensity. The purpose of this paper is to analyze how much safety culture of air traffic controllers has effect on their complexity mitigation strategies during their duties. It could be expected complexity mitigation improve air traffic flow resulting in enhancing safety eventually. According to empirical analysis against air traffic controllers in civil aviation and air force in South Korea, it was proven safety culture had a statistically positive effect on complex mitigation strategies through safety behavior. In safety culture among air traffic controllers, intrinsic culture had a positive effect on extrinsic value of safety culture. Intrinsic value of safety culture led to air traffic controllers' safety behavior which created work complexity mitigation strategies. Among work complexity mitigation strategies, communication and cooperation was proven to be the most important factor effected by safety culture and behavior. It was implied that enhancing the intrinsic values of safety culture would cause to improve extrinsic safety culture and air traffic controller's work efficiency.

• Asian Journal of Business Environment
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• v.11 no.4
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• pp.5-16
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• 2021

Purpose: This study aims to investigate the impact of auditor-client traffic convenience on accrual -based and real earnings management of the client firms. Research design, data and methodology: Using a sample of firms listed in Shanghai and Shenzhen Stock Exchanges over the period of 2007 to 2018, this paper empirically investigates the association between auditor-client traffic convenience and earnings management. We use three measures of auditor-client traffic convenience: railway traffic convenience, expressway traffic convenience, and air traffic convenience. The accrual-based earnings management is measured by abnormal accruals estimated by industry and year using the Modified Jones Model. Results: Findings indicate that traffic convenience is conducive to detecting and restraining positive accrual earnings management and real earnings management. After changing the measurement of independent variable and dependent variable, including potential omitted variables, the results are statistically unchanged. Further, the research shows that traffic convenience can not only improve audit quality, but also lead to higher fee premiums. Auditors didn't share with clients the cost reduction benefits caused by traffic convenience. Conclusions: Traffic convenience provides auditors with easy access to the client firms, alleviating the information asymmetry and improving corporate earnings quality. The findings have implications for regulators, audit practitioners and stakeholders.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.397-404
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• 2009

In this paper, we propose a method of monitoring traffic and analyzing information of handover in mobile IPv6 networks. Our proposed method analyzes handover latency through monitoring packets at routers without installing monitoring applications at mobilenodes. For this purpose, we employ a flow-based traffic monitoring standard called IPFIX to perform the traffic measurement function the packets at the routers. Therefore, our method is useful in that we could easily obtain information regarding handover of mobile nodes by only monitoring traffic at the routers. In order to verify the proposed method, we carried out experiments in a real 802.11-based mobile IPv6 network testbed. From our experimental results, it was shown that the calculated handover latency for uploading traffic is accurate with less accuracy of analyzing the handover latency for downloading traffic.

• Journal of the Korea Society of Computer and Information
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• v.26 no.9
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• pp.133-141
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• 2021

The development and demand for the system that provides users with traffic information and efficient road use have continued. also, this system provides the basic technology of the Intelligent Transport System (ITS). The most used traffic information collection tools are Vehicle detectors (VDS) and short-range wireless communication (DSRC) on express way. In order to generate reliable traffic information, it is necessary to efficiently manage and utilize the collected data as well as high-quality traffic data collection and processing technology. In this study, traffic information collection·processing·provision systems were investigated, and analyze the current status and problems of traffic information collected through VDS. Based on this, we would like to present an improved collection algorithm that utilizes the Kalman filter for vehicle information measurement of VDS data. By using the algorithm of this study, it is possible to minimize the time delay of the estimated value as well as the noise removal that inevitably occurs during measurement.

• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1788-1796
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• 1997

In this paper, we propose a new connection admission control(CAC) algorithm for traffic control in ATM network in which traffic estimation is performed based on user-specified parameters at every moment of connection request or connection release by recursive formula which makes real-time calculation possible. And traffic estimation using cell flow measurement is carried out when the number of connectioned calls does not change during a measurement reflection period. Performance analysis of the proposed method is carried out using several aspects for homogeneous and heterogeneous bursty traffic. The results showed that the proposed CAC method revealed better performance, than conventional CAC method for burst model in both utilization and QoS point of view.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.3
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• pp.37-44
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• 2011

Recently malicious activities that is a DDoS, spam, propagation of malware, steeling person information, phishing on the Internet are related malicious botnet. To detect malicious botnet, Many researchers study a detection system for malicious botnet, but these applies specific protocol, action or attack based botnet. In this reason, we study a selection of measurement to detec malicious botnet in this paper. we collect a traffic of malicious botnet and analyze it for feature of network traffic. And we select a feature based measurement. we expect to help a detection of malicious botnet through this study.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2006.11a
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• pp.30-33
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• 2006

The purpose of this study is the improvement of the prediction model of highway noise. It includes the measurement and analysis of the highway noise for various types of roads and environments. The results of the measurement are compared with the noise levels predicted by highway noise prediction models including domestic and foreign ones and any recommendation to improve the accuracy of the models should be provided.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.23 no.1
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• pp.82-96
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• 2024

While analyzing traffic flow, speed, traffic volume, and density are important macroscopic indicators, and acceleration and spacing are the important microscopic indicators. The speed and traffic volume can be collected with the currently installed traffic information collection devices. However, acceleration and spacing data are necessary for safety and autonomous driving but cannot be collected using the current traffic information collection devices. 'You Look Only Once'(YOLO), an object recognition technique, has excellent accuracy and real-time performance and is used in various fields, including the transportation field. In this study, to measure acceleration and spacing using YOLO, we developed a model that measures acceleration and spacing through changes in vehicle speed at each interval and the differences in the travel time between vehicles by setting the measurement intervals closely. It was confirmed that the range of acceleration and spacing is different depending on the traffic characteristics of each point, and a comparative analysis was performed according to the reference distance and screen angle to secure the measurement rate. The measurement interval was 20m, and the closer the angle was to a right angle, the higher the measurement rate. These results will contribute to the analysis of safety by intersection and the domestic vehicle behavior model.

• Journal of Environmental Health Sciences
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• v.34 no.5
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• pp.395-402
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• 2008

Road traffic noise causes considerable disturbance and annoyance in exposed inhabitants. Particularly, arterial road noise is a significant environmental problem in many urban areas in which higher traffic volume and higher car speed occur. Arterial road noise became the target of this investigation in Seoul, South Korea. Noise levels were measured at four points that were based on distance from roadside at the same measurement site and under the conditions as reported by the National Institute of Environmental Research (NIER) in 1999. The average noise levels ($L_{eq,1h}$) of the arterial road was 80.3 dBA at 5 m, 77.4 dBA at 10 m, 73.7 dBA at 20 m, 70.9 dBA at 30 m. A comparison between 1999 and 2008's measurement values has shown that in 2008 noise level is up by about 1.5 dBA, traffic volume has increased by about 15.7%, while car speed has decrease by about 8%. The relationship between 2008' measured values and predicted values using the NIER Equation is low under 10 m from the roadside. The influence range of arterial noise is calculated at 26 m for road noise limits in daytime. In relation to the comparison between traffic volume and noise level, the equivalence in traffic volume (Light car+10xHeavy car) is higher than other variables.