• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.63-67
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• 2009

In this paper we propose a QoS policy, which is based on both DSCP and SPQ, appropriate to TPS users on optical subscriber network. Then we experiment and evaluate QoS policy through the test bed which emulates real optical subscriber network. In order to perform effective and real experiment on test bed we make test traffic equivalent to 400 TPS users and give it to test bed. The experimental result shows that no packet loss in real time service traffic such as voice, IPTV occurs during more than 4 hours. We think that our proposed QoS policy is a proper method which guarantees the service quality of real time services on optical subscriber network.

• Journal of Korean Society of Transportation
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• v.33 no.1
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• pp.14-28
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• 2015

Numerous research has been conducted using internet search data since the mid-2000s. For example, Google Inc. developed a service predicting influenza patterns using the internet search data. The main objective of this study is to prove the hypothesis that highway traffic indices are similar to the internet search patterns. In order to achieve this objective, a model to predict the number of vehicles entering the expressway and space-mean speed was developed and the goodness-of-fit of the model was assessed. The results revealed several findings. First, it was shown that the Google search traffic was a good predictor for the TCS entering traffic volume model at sites with frequent commute trips, and it had a negative correlation with the TCS entering traffic volume. Second, the Naver search traffic was utilized for the TCS entering traffic volume model at sites with numerous recreational trips, and it was positively correlated with the TCS entering traffic volume. Third, it was uncovered that the VDS speed had a negative relationship with the search traffic on the time series diagram. Lastly, it was concluded that the transfer function noise time series model showed the better goodness-of-fit compared to the other time series model. It is expected that "Big Data" from the internet search data can be extensively applied in the transportation field if the sources of search traffic, time difference and aggregation units are explored in the follow-up studies.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.45-48
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• 2002

This paper presents a QoS-guaranteed traffic control system which supports QoS of realtime packet transmission for the multimedia communication. The traffic control system presented in this paper applies the integrated service model and provides QoS o(packet transmission by means of determining the packet transmission rate with the policy of network manager and the optimal resource allocation according to the end-to-end traffic load. It also provides QoS for the realtime packet transmission through the AWF2Q+ Scheduling algorithm and per-class queuing method.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.1
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• pp.31-38
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• 2012

Next generation cellular applications and smart phone usage generate very heavy wireless data traffic. It becomes ineluctable for mobile network operators to have multiple core network entities such as Serving Gateway and Packet Data Network Gateway in 4G-LTE to share this high traffic generated. A typical configuration consists of multiple serving gateways behind a load-balancer which would determine which serving gateway would service a end-users'request. Such hardware is expensive, has a rigid policy set, and is a single point of failure. Another perspective of today's increasingly high data traffic is that besides it is being widely accepted that the high bandwidth L TE provides is creating bottlenecks for service providers by the increasing user bandwidth demands without creating any corresponding revenue improvements, a hidden problem that is also passively advancing on the newly emerging 4G-LTE that may need more immediate attention is the network signaling traffic, also known as the control-plane traffic that is generated by the applications developed for smartphones and tablets. With this as starting point, in this paper, we propose a solution, by a new approach considering OpenFlow switch connected to a controller, which gains flexibility in policy, costs less, and has the potential to be more robust to failure with future generations of switches. This also solves the problem of scaling the control-plane traffic that is imperative to preserve revenue and ensure customer satisfaction. Thus, with the proposed architecture with OpenFlow, mobile network operators could manipulate the traffic generated by the control-plane signaling separated from the data-plane, besides also reducing the cost in installing multiple core-network entities.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.9
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• pp.89-96
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• 2016

According to the promoting policy for bicycle riding, the bicycle road infrastructure in Korea has been widely established. As the number of bicycle rider increases, bicycle traffic accidents also increase year after year. In this paper, we analyze bicycle traffic accident data from 2007 to 2014 which is provided by Road Traffic Authority and present statistical results of bicycle traffic accidents. And also regression analysis is applied to predict the number of daily traffic accidents in Seoul using ASOS(Automated Synoptic Observing System) climate data observed in the Seoul sector which are provided by Korea Meteorological Administration. In addition, decision tree analysis techniques are used to forecast the level of traffic accidents severity. In the analytic results of this research, we expect that it will be helpful to establish the collective policy of bicycle accident data and protective strategy in order to reduce the number of bicycle accidents.

• The Korean Journal of Air & Space Law and Policy
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• v.18
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• pp.105-134
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• 2003

This paper describes generic cognitive aspects of the air traffic controller's performance and perceptive activities unveiled through the past literature study. which underlines mental modelling and mental picture presented in the middle of complicated situational awareness and decision making process when air traffic controller comes to determine the distance between aircraft under control to maintain air traffic in a safe, orderly and expeditious way. It also describes human limit in terms of human memory in conjunction with relative workloads and environmental factor. In conclusion, It suggest that ATC authority will take into account the qualitatiive adjustment of training requirement necessary for ATC facility rating and refresher training to allow them more preparedness for better situational awareness and optimal decision making. In this paper controller's behavioral activators affecting their job performance are addressed in perspective of aviation safety.

• Journal of Environmental Health Sciences
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• v.30 no.3
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• pp.283-292
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• 2004

Valid evaluation of community reaction to road-traffic noise exposure is important for the policy making and quality of life. The purpose of this study is to evaluate the relationship between community reaction and nighttime road-traffic noise. The study measured nighttime roadside noise caused by high traffic which is greater than LAeq(22:00-07:00) 65dB(A) and lower than 65dB(A) at Chonju city, from March to April, 2003. Three hundred sixty seven subjects, aged from 20 to 65, were selected from those who are residing close to the major roads. They were asked to answer the questions regarding noise source, stress(PWI-SF), annoyance, disturbance of specific activity, disturbance of sleep, somatic symptom, and four suggested confounding factors. The relationship between annoyance, somatic symptom and noise exposure was not significant. Adjusted odds ratio(95% C.I.) for disturbance of communication　 and disturbance of attention and rest　 were 1.59(1.03-2.71), 1.64(1.06-2.81), respectively. On the other hand sleep disturbance　 was indicated as 1.34(0.77-2.32). The results suggested that federal policy-making about road-traffic noise should consider community reaction evaluated by various perspective including annoyance, disturbance of specific activity, disturbance of sleep, and confounding factors.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.10
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• pp.817-823
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• 2013

This paper examined the performance of differentiated services applied to each different traffic. For this purpose, we used three traffics which have a different quality of service and generate packets from a specific source to destination. To allocate a proper code point according to QoS, a common policy which is the simple policy model of time sliding window with 3 color marking (TSW3CM) was established to each traffic. To evaluate the performance, we investigate and compare code points to each traffic. Simulation results using NS-2 showed that the code points 10, 11, and 12 can be differently allocated to each traffic according to its sending rates 1Mbps, 2.5Mbps, and 4Mbps.

• Transportation Technology and Policy
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• v.12 no.1
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• pp.83-92
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• 2015

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.6
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• pp.1297-1308
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• 2015

In Korea, the local traffic safety master plan has been established and implemented according to the Traffic Safety Act. Each local government is required to establish a customized traffic safety policy and share roles for improvement of traffic safety and this means that local governments lead and promote effective local traffic safety policies fit for local circumstances in substance. For implementing efficient traffic safety policies, which accord with many-sided characteristics of local governments, the prediction of community-based traffic accidents, which considers local characteristics and the analysis of accident influence factors must be preceded, but there is a shortage of research on this. Most of existing studies on the community-based traffic accident prediction used social and economic variables related to accident exposure environments in countries or cities due to the limit of collected data. For this reason, there was a limit in applying the developed models to the actual reduction of traffic accidents. Thus, this study developed a local traffic accident prediction model, based on smaller regional units, administrative districts, which were not omitted in existing studies and suggested a method to reflect traffic safety facility and policy variables that traffic safety policy makers can control, in addition to social and economic variables related to accident exposure environments, in the model and apply them to the development of local traffic safety policies. The model development result showed that in terms of accident exposure environments, road extension, gross floor area of buildings, the ratio of bus lane installation and the number of crossroads and crosswalks had a positive relation with accidents and the ratio of crosswalk sign installation, the number of speed bumps and the results of clampdown by police force had a negative relation with accidents.