• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권2호
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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.

• 한국항만학회지
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• 제13권1호
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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.

• 한국ITS학회 논문지
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• 제22권1호
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• pp.311-326
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• 2023

본 연구는 자율주행차량과 일반차량의 인지 방식과 범위의 차이를 비교하고 미시적 교통시뮬레이션을 활용한 교통안전시설의 설치 및 운영 개선방안을 제안하는 것을 목적으로 하였다. 연구에서는 기존 교통안전표지 설치·관리 업무편람을 검토하고 교통안전시설 중 안전표지를 차량의 행동 변화에 따라 분류하였다. 이후, 분류된 시설에 대해 가상환경에서 시뮬레이션 실험을 통해 안전표지의 설치 위치를 변경해가며 최적 설치지점을 추론하여 개선방안을 제시하였다. 본 연구는 일반 운전자의 시인성을 기준으로 설치된 교통안전시설이 자율주행차량과 일반차량이 혼재된 상황에서 도로 효율성과 안전성에 어떠한 영향을 주는지 확인하였다. 본 연구를 통해 도출한 교통안전시설의 인지에 대한 임곗값은 교통안전시설의 설치·관리에 관한 규칙의 개정 근거로 활용될 수 있다는 데 의의가 있다.

• 한국항공운항학회지
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• 제22권4호
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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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• 제9권5호
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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.

• 한국항공운항학회지
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• 제22권4호
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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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• 제15권1호
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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.

• 한국콘텐츠학회논문지
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• 제7권2호
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• pp.63-72
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• 2007

교통 표지판은 먼거리에서도 교통 표지라는 것을 쉽게 판별하여 단시간 내에 그 내용을 파악할 수 있어야 한다. 교통 표지판의 도로의 안전 주행에 있어 아주 중요한 객체로 도로 상의 다른 그 무엇보다도 먼저 인간의 시선을 잡아끌어야 한다. 이에 본 논문에서는 인간의 도로 상의 어떤 물체보다도 교통 표지판에 가장 먼저 시선을 집중한다는 가정하에 주의 모듈(Attention Module)을 사용하여 교통 표지판 영역을 추출하는 시스템을 제안하고자 한다. 특히 본 논문에서는 인간의 대상(object)인식과정, 특히 색상처리과정에서 어떠한 특징들이 사용되어지는지를 기존의 정신물리학적, 생리학적 실험결과를 통해 분석하였고, 이 분석결과를 통해 얻어진 특징들을 사용하여 교통 표지판 영역을 추출하였다. 실제 도로위에서 찍은 실영상을 대상으로 실험하였으며, 실험을 통하여 평균 97.8%의 탐지율을 보임을 확인하였다.

• 한국심리학회지 : 문화 및 사회문제
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• 제16권3호
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• pp.267-287
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• 2010

본 연구는 우리나라의 교통사고 조사양식을 개선하고 이를 통해 사고조사 자료의 신뢰성을 확보하여 인적 사고관련 요인 판단에 도움을 줄 수 있는 방안을 모색하기 위해 실시되었다. 먼저 교통사고 조사양식 개선안을 만들기 위해 미국과 영국에서 사용하고 있는 조사양식 및 관련 연구들이 제시한 항목들을 분석하였다. 또, 이렇게 만들어진 조사양식 개선안이 충분한 사고설명력을 가지는지 알아보기 위해 2008년 한 해 동안 경기도에서 발생한 사망사고 중 502건을 새로 분석하여 기존 항목에 의한 분석결과와 비교하였다. 분석결과, 도로환경 부문과 운전자 요인 부문에서 일부 불명확한 내용의 기존항목이 제거되고, 새로운 내용들이 사고조사 양식에 반영되어야 할 필요성이 제기되었다. 본 연구결과를 바탕으로 인적요인을 고려한 교통사고 조사양식 개선안과 추후 연구과제들을 논의와 부록자료를 통해 제안하였다.

• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2018년도 공동국제학술발표회
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• pp.50-50
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• 2018