• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.1
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• pp.265-275
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• 2023

The purpose of this paper is to devise an optimal route allocation algorithm for automated vehicle(AV) in monitoring quality of road infrastructure to support the road safety. The tasks of an AV in this paper include visiting node-links at least once during its operation and checking status of road infrastructure, and coming back to its depot.. In selecting optimal route, its priority goal is visiting the node-links with higher risks while reducing costs caused by operation. To deal with the problem, authors devised reward maximizing algorithm for AVs. To check its validity, the authors developed simple toy network that mimic node-link networks and assigned costs and rewards for each node-link. With the toy network, the reward maximizing algorithm worked well as it visited the node-link with higher risks earlier then chinese postman route algorithm (Eiselt, Gendreau, Laporte, 1995). For further research, the reward maximizing algorithm should be tested its validity in a more complex network that mimic the real-life.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.21 no.6
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• pp.299-310
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• 2022

The ability of an automated driving system is based on vehicle sensors, judgment and control algorithms, etc. The safety of automated driving system is highly related to the operational status of the road network and compliant road infrastructure. The safe operation of automated driving necessitates continuous monitoring to determine if the road and traffic conditions are suitable and safe. This paper presents a node and link system to build a road monitoring system by considering the ODD(Operational Design Domain) characteristics. Considering scalability, the design is based on the existing ITS standard node-link system, and a method for expressing the monitoring target as a node and a link is presented. We further present a technique to classify and manage hazard risk into five levels, and a method to utilize node and link information when searching for and controlling the optimal route. Furthermore, we introduce an example of system implementation based on the proposed node and link system for Sejong City.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.102-113
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• 2023

With the increasing use of E-scooters, there is an urgent need for research into their driving risks because of the rising number of related accidents. Existing theoretical analysis methods are primarily vehicle-centered and do not adequately reflect the lightweight and compact characteristics of E-scooters. This study was conducted on real roads to analyze the risk and stable speeds of drivers on longitudinal slopes, considering the unique attributes of E-scooters. The risk speed on slopes was, on average, 21 km/h, with the initial risk speed decreasing as the slope became steeper. The stable speed was determined to be an average of 17 km/h, except on slopes of 1-2%, which presented a relatively low risk. These results are expected to contribute to the academic foundation for policies aimed at reducing the top speed of personal mobility, as is currently being promoted in Korea.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.2
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• pp.167-175
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• 2020

The Two-fluid Model, proposed by Herman and Prigogine in 1979, is a macroscopic model for describing network operability in urban networks. Since the Two-fluid Model parameters change according to the traffic flow characteristics, it is necessary to identify the cause of flow change when analyzing the operability using the parameters. This study compared the crash risk according to rainfall using the Two-fluid Model parameters, and explained that the driving behavior affects the operability of the urban network. The results of the parameters estimation showed poor network operation under rainfall condition. The factors of drivers' crash risk perception model were calculated, and driving behavior was analyzed due to crash risk according to rainfall. In both the morning and evening, drivers tended to slow down their speeds to reduce the crash risk, because the risk on rainy days could be high when the speed was the same as on a sunny days. However, the crash risk was still higher on rainy days than sunny. In the future, it is necessary to analyze the relationship between the network operation and the crash risk in various networks and to improve both.

• Proceedings of the KAIS Fall Conference
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• 2009.12a
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• pp.864-867
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• 2009

고속도로를 주행하는 차량에 작용하는 순간적인 강풍은 차량의 주행경로이탈, 차체의 수평회전 과다와 전도를 발생시키는 원인이 되며, 이로 인한 교통사고는 치명적인 대형사고로 이어질 가능성이 높다. 최근에 건설되거나 추진중인 고속도로는 고속운행에 필요한 도로선형을 확보하기 위해 계곡부를 통과하는 높은 위치에 교량을 건설하거나 산악터널을 내는 경우가 많으며, 지형적인 특성으로 발생하는 국지적인 강풍의 영향이 매우 크기 때문에 적극적인 강풍저감대책이 필요하다. 본 연구에서는 강풍 발생지역을 주행중인 차량의 안전성 및 쾌적성확보를 위하여 차량의 동역학적 거동을 규명하고 차종별 주행속도와 순간풍속의 상관관계를 정립하였다. 또한 차량사고의 영향인자별 분석을 통하여 기존에 제시된 연구결과와 기준안에 대한 고찰을 실시하였고, 강풍발생 지역을 통과하는 차량에 대한 규제와 운영방법에 대해 위험풍속을 정의하고 차량속도규제(안)을 제시하였다.

• Journal of Platform Technology
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• v.11 no.3
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• pp.24-31
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• 2023

Recently, interest in UAM (Urban Air Mobility, UAM), which can take off and land vertically in the operation of urban air transportation systems, has been increasing. Therefore, various start-up companies are developing related technologies as eco-friendly future transportation with advanced technology. However, studies on ways to increase safety in the operation of UAM are still insignificant. In particular, efforts are more urgent to improve the safety of risks generated in the process of attempting to land in the city center by UAM equipped with autonomous driving. Accordingly, this study proposes a plan to safely land by avoiding dangerous region that interfere when autonomous UAM attempts to land in the city center. To this end, first, the latitude and longitude coordinate values of dangerous objects observed by the sense of the UAM are calculated. Based on this, we proposed to convert the coordinates of the distorted planar image from the 3D image to latitude and longitude and then use the calculated latitude and longitude to compare the pre-learned feature descriptor with the HOG (Histogram of Oriented Gradients, HOG) feature descriptor to extract the dangerous Region. Although the dangerous region could not be completely extracted, generally satisfactory results were obtained. Accordingly, the proposed research method reduces the enormous cost of selecting a take-off and landing site for UAM equipped with autonomous driving technology and contribute to basic measures to reduce risk increase safety when attempting to land in complex environments such as urban areas.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.8
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• pp.287-300
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• 2021

Collaborative Cyber-Physical Systems (CCPS) are those systems that contain tightly coupled physical and cyber components, massively interconnected subsystems, and collaborate to achieve a common goal. The safety of a single Cyber-Physical System (CPS) can be achieved by following the safety standards such as ISO 26262 and IEC 61508 or by applying hazard analysis techniques. However, due to the complex, highly interconnected, heterogeneous, and collaborative nature of CCPS, a fault in one CPS's components can trigger many other faults in other collaborating CPSs. Therefore, a safety assurance technique based on fault criticality analysis would require to ensure safety in CCPS. This paper presents a Fault Criticality Matrix (FCM) implemented in our tool called CPSTracer, which contains several data such as identified fault, fault criticality, safety guard, etc. The proposed FCM is based on composite hazard analysis and content-based relationships among the hazard analysis artifacts, and ensures that the safety guard controls the identified faults at design time; thus, we can effectively manage and control the fault at the design phase to ensure the safe development of CPSs. To justify our approach, we introduce a case study on the Platooning system (a collaborative CPS). We perform the criticality analysis of the Platooning system using FCM in our developed tool. After the detailed fault criticality analysis, we investigate the results to check the appropriateness and effectiveness with two research questions. Also, by performing simulation for the Platooning, we showed that the rate of collision of the Platooning system without using FCM was quite high as compared to the rate of collisions of the system after analyzing the fault criticality using FCM.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.44 no.1
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• pp.63-73
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• 2024

Autonomous vehicles at Levels 3 to 5, currently under global research and development, seek to replace the driver's perception, judgment, and control processes with various sensors integrated into the vehicle. This integration enables artificial intelligence to autonomously perform the majority of driving tasks. However, autonomous vehicles currently obtain temporary driving permits, allowing them to operate on roads if they meet minimum criteria for autonomous judgment abilities set by individual countries. When autonomous vehicles become more widespread in the future, it is anticipated that buyers may not have high confidence in the ability of these vehicles to avoid hazardous situations due to the limitations of temporary driving permits. In this study, we propose a method for grading the judgment abilities of autonomous vehicles based on a driving simulator experiment comparing and evaluating drivers' abilities to avoid hazardous situations. The goal is to derive evaluation criteria that allow for grading based on specific scenarios and to propose a framework for grading autonomous vehicles. Thirty adults (25 males and 5 females) participated in the driving simulator experiment. The analysis of the experimental results involved K-means cluster analysis and independent sample t-tests, confirming the possibility of classifying the judgment abilities of autonomous vehicles and the statistical significance of such classifications. Enhancing confidence in the risk-avoidance capabilities of autonomous vehicles in future hazardous situations could be a significant contribution of this research.

• Proceedings of the KOR-KST Conference
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• 1999.10a
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• pp.141-146
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• 1999

본 연구는 평면곡선부의 차량속도변화와 교통사고에 대한 영향을 분석하기 위해 수행되었으며, 이를 위해 곡선반경별로 진입부 직선도로 - 곡선부 - 이탈부 직선도로로 구분하여 각 주행속도를 산정하였다. 본 연구에서는 선행차량에 의해 영향을 받지 않는 속도를 이용하여 평면곡선부 기하구조의 영향을 분석하였다. 이러한 곡선부의 주행 속도를 분석한 결과, 곡선반경별 최저속도와 그 속도가 나타나는 위치를 분석하였고, 해당 도로구간의 교통사고자료를 분석하여 평면곡선부의 차량주행속도변화와 교통사고 발생간의 관계를 규명하였다. 연구 결과는 다음과 같다. 첫째, 운전자들은 곡선시작지점에 도착하기 전에 충분히 속도를 줄이고, 곡선부에서 가장 낮은 속도가 나타나는 위치는 곡선시점의 후방에서 나타나고 이는 운전자의 시거에 의한 영향이다. 둘째, 곡선부에서의 속도변화폭이 클수록 사고위험성은 크고 실제 교통사고의 발생건수는 높다. 본 연구의 결과에 의해 도로 주행의 안전성을 고려한 평가지표를 개발할 수 있으며, 이에 의한 일관성 있는 도로설계를 유도할 수 있다.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.1
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• pp.17-26
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• 2010

This study presents a decision making process for installation of wind barrier which is used to reduce the wind acting on running vehicle on expressway. At the first stage of this study, the lateral deviations of running vehicles under side winds were computed from the commercial softwares, CarSim and TruckSim, and then the critical wind speeds for car accident were evaluated from predefined risk index. To determine whether it is needed to install wind barrier or not, cost and benefit from wind barrier are calculated during lifetime. In obtaining car accidental risk, probabilistic distribution of wind speed, daily traffic volume, mixture ratio in the volume, and duration time for wind speed range are considered. It is recommended to install wind barrier if benefit from the barrier installation exceed construction cost. In the numerical examples, case studies were shown for risk and benefit calculation and main risky regions on Korean highway were all evaluated to identify the number of installation sites.