• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.2
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• pp.687-708
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• 2017

The machine-to-machine (M2M) communication is featured by tremendous number of devices, small data transmission, and large uplink to downlink traffic ratio. The massive access requests generated by M2M devices would result in the current medium access control (MAC) protocol in LTE/LTE-A networks suffering from physical random access channel (PRACH) overload, high signaling overhead, and resource underutilization. As such, fairness should be carefully considered when M2M traffic coexists with human-to-human (H2H) traffic. To tackle these problems, we propose an adaptive Slotted ALOHA (S-ALOHA) and time division multiple access (TDMA) hybrid protocol. In particular, the proposed hybrid protocol divides the reserved uplink resource blocks (RBs) in a transmission cycle into the S-ALOHA part for M2M traffic with small-size packets and the TDMA part for H2H traffic with large-size packets. Adaptive resource allocation and access class barring (ACB) are exploited and optimized to maximize the channel utility with fairness constraint. Moreover, an upper performance bound for the proposed hybrid protocol is provided by performing the system equilibrium analysis. Simulation results demonstrate that, compared with pure S-ALOHA and pure TDMA protocol under a target fairness constraint of 0.9, our proposed hybrid protocol can improve the capacity by at least 9.44% when ${\lambda}_1:{\lambda}_2=1:1$and by at least 20.53% when ${\lambda}_1:{\lambda}_2=10:1$, where ${\lambda}_1,{\lambda}_2$ are traffic arrival rates of M2M and H2H traffic, respectively.

• Journal of Korean Port Research
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• v.13 no.1
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• pp.101-112
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• 1999

Traffic accidents increase with the increase of the vehicles in operation on the street. Especially big traffic accidents composed of over 3 killed or 20 injured accidents with the property damage become one of the serious problems to be solved in most of the cities. The purpose of this study is to build the discrimination model on big traffic accidents using the Quantification II theory for establishing the countermeasures to reduce the big traffic accidents. The results are summarized as follows. 1)The existing traffic accident related model could not explain the phenomena of the current traffic accident appropriately. 2) Based on the big traffic accident types vehicle-vehicle, vehicle-alone, vehicle-pedestrian and vehicle-train accident rates 73%, 20.5% 5.6% and two cases respectively. Based on the law violation types safety driving non-fulfillment center line invasion excess speed and signal disobedience were 48.8%, 38.1% 2.8% and 2.8% respectively. 3) Based on the law violation types major factors in big traffic accidents were road and environment, human, and vehicle in order. Those factors were vehicle, road and environment, and human in order based on types of injured driver’s death. 4) Based on the law violation types total hitting and correlation rates of the model were 53.57% and 0.97853. Based on the types of injured driver’s death total hitting and correlation rates of the model were also 71.4% and 0.59583.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.311-326
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• 2023

This paper proposes a plan to improve the installation and operation of traffic safety facilities using a microscopic simulation by confirming the difference in the perception method and range of autonomous vehicles and human vehicles. In this study, the existing 『Traffic Safety Sign Installation·Management Guidelines』 was reviewed, and safety signs among traffic safety facilities were classified according to changes in vehicle behavior. Subsequently, for the classified facilities, the installation location of the traffic sign was changed through simulation experiments, and the optimal location was inferred to suggest an improvement plan. This study confirmed how traffic safety facilities installed based on the visibility of human drivers affect road efficiency and safety in mixed traffic flow with autonomous vehicles and human-controlled vehicles. The optimal location derived through this study is meaningful because it can be used as the basis for revising the guidelines on the installation and management of traffic safety facilities.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.4
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• pp.34-41
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• 2014

Aviation safety issues have drawn much attention from the international community due to the growing demand for air travel. Although it is a widely accepted fact that human-related factors are closely linked to aviation safety, there is lack of understanding what roles those factors play in aviation, in the field of air traffic control in particular. It has been reported that the role of air traffic controllers significantly affects air safety. This review will discuss cognitive aspects of expertise in air traffic control including time perception, working memory, reasoning, perception, attention, scanning/vigilance, decision making, and planning with examples of how each aspect can be dealt with in performing air traffic control duties. The relevant studies in psychology have also been briefly reviewed in the interest of enhancing understanding of characteristics of air traffic control tasks and the related human factors. This review concludes with a call for more in-depth research into cognitive factors in air traffic control.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1881-1903
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• 2015

With the fast-developing of mobile terminals, positioning techniques based on fingerprinting method draws attention from many researchers even world famous companies. To conquer some shortcomings of the existing fingerprinting systems and further improve its performance, we propose a radio map building and updating technique, which is able to customize the spatial and temporal dependency of radio maps. The method includes indoor propagation and penetration modeling and the analysis of human traffic. Based on the combination of Ray-Tracing Algorithm, Finite-Different Time-Domain and Rough Set Theory, the approach of indoor propagation modeling accurately represents the spatial dependency of the radio map. In terms of temporal dependency, we specifically study the factor of moving people in the interest area. With measurement and statistics, the factor of human traffic is introduced as the temporal updating component. We improve our existing indoor positioning system with the proposed building and updating method, and compare the localization accuracy. The results show that the enhanced system can conquer the influence caused by moving people, and maintain the confidence probability stable during week, which enhance the actual availability and robustness of fingerprinting-based indoor positioning system.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.22 no.4
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• pp.1-7
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• 2014

The purpose of study is to investigate the current user interface level of air traffic control system with the usability analysis and satisfaction survey questionnaire on user satisfaction. Think aloud protocol is used to identify not only task analysis, but also the level of user-friendliness of the FIMS and ASDE system, and the user interface questionnaires was conducted by QUIS. We collected data from 6 controllers for Think aloud protocol and 15 controllers for QUIS in Incheon airport. The results showed that the system was the valuable tool for ensuring human performance with the support of memory and the facilitation of decision-making tasks. It helps air traffic controllers perform better and minimize errors in a congested time. The human-computer interface system design, however, was not applied, which led to the increase of workload. Air traffic controller participation in software development provided excellent examples for applications in terms of software in FIMS. Based on these results, the study provided that the usability of system interface was necessary to take into account human factors. The development and design of system was discussed in User Interface environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.1
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• pp.114-130
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• 2021

With the drastic growth of Information and Communication Technology (ICT) industry, global energy consumption is exponentially increased by mobile communications. The huge energy consumption and increased environmental awareness have triggered great interests on the research of dynamic distribution of cell user and traffic, and then designing the energy efficient cellular network. In this paper, we explore the temporal and spatial characteristics of human mobility and traffic distribution using real data set. The analysis results of cell traffic illustrate the tidal effect in temporal and spatial dimensions and obvious periodic characteristics which can be used to design Base Station (BS) dynamic with sleeping or shut-down strategy. At the same time, we designed a new Cell Zooming and BS cooperation mode. Through simulation experiments, we found that running in this mode can save about 35% of energy consumption and guarantee the required quality of service.

• The Journal of the Korea Contents Association
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• v.7 no.2
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• pp.63-72
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• 2007

The traffic sign on the road should be easy to distinguishable even from far, and should be recognized in a short time. As traffic sign is a very important object which provides important information for the drivers to enhance safety, it has to attract human's attention among any other objects on the road. This paper proposes a new method of detecting the area of traffic sign, which uses attention module on the assumption that we attention our gaze on the traffic sign at first among other objects when we drive a car. In this paper, we analyze the previous studies of psycophysical and physiological results to get what kind of features are used in the process of human's object recognition, especially color processing, and with these results we detected the area of traffic sign. Various kinds of traffic sign images were tested, and the results showed good quality(average 97.8% success).

• Korean Journal of Culture and Social Issue
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• v.16 no.3
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• pp.267-287
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• 2010

This study aimed to improve the Traffic Accident Management System's validity and reliability, so the system could help classify and judge the human factors that correlate with traffic accidents. We took traffic accident research and analysis systems of United States and United Kingdom and certain related, former studies into account in building our test system. Next, we used the test system's criteria to re-analyze 502 Gyeonggi province accident records from 2008. We compared the results to existing systems' results to verify the test system's validity and reliability. These results indicated the necessity of removing some uncertain items from the existing systems and adding in some new items from the test system. This should help improve understanding of what happens at traffic accident scenes and of the sources of drivers' abnormal, reckless behavior. We introduce suggestions for improving the Traffic Accident Management System and research concepts for further studies.

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.50-50
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• 2018