• 인터넷정보학회논문지
• /
• 제16권6호
• /
• pp.57-67
• /
• 2015

This paper proposes an Fuzzy-based Risk Reasoning Driving Strategy on VANET. Its first reasoning phase consists of a WC_risk reasoning that reasons the risk by using limited road factors such as current weather, density, accident, and construction, a DR_risk reasoning that reasons the risk by combining the driving resistance with the weight value suitable for the environment of highways and national roads, a DS_risk reasoning that judges the collision risk by using the travel direction, speed. and distance of vehicles and pedestrians, and a Total_risk reasoning that computes a final risk by using the three above-mentioned reasoning. Its second speed reduction proposal phase decides the reduction ratio according to the result of Total_risk and the reduction ratio by comparing the regulation speed of road to current vehicle's speed. Its third risk notification phase works in case current driving speed exceeds regulation speed or in case the Total_risk is higher than AV(Average Value). The Risk Notification Phase informs rear vehicles or pedestrians around of a risk according to drivers's response. If drivers use a brake according to the proposed speed reduction, the precedent vehicles transfers Risk Notification Messages to rear vehicles. If they don't use a brake, a current driving vehicle transfers a Risk Message to pedestrians. Therefore, this paper not only prevents collision accident beforehand by reasoning the risk happening to pedestrians and vehicles but also decreases the loss of various resources by reducing traffic jam.

• Wind and Structures
• /
• 제37권4호
• /
• pp.275-287
• /
• 2023

Subgrade differential settlement of high-speed railways was a pivotal issue that could increase the risk of trains operation. The risk will be further increased when trains in the subsidence zone are affected by crosswinds. In this paper, the computational fluid dynamics (CFD) model and finite element (FE) model were established, and the data transmission interface of the two models was established by fluid-solid interaction (FSI) method to form a systematic crosswind-train-track-subgrade dynamic model. The risk of high-speed train encountering crosswind in settlement area was analyzed. The results showed that the aerodynamic force of the trains increased significantly with the increase in crosswind speed. The aerodynamic force of the trains could reach 125.14 kN, significantly increasing the risk of derailment and overturning. Considering the influence of crosswind, the risk of train operation could be greatly increased. The safety indices and the wheel-rail force both increased with the increase of the wind speed. For the high-speed train running at 350 km/h, the warning value of wind speed was 10.2 m /s under the condition of subgrade settlement with wavelength of 20 m and amplitude of 15 mm.

• 한국안전학회지
• /
• 제31권5호
• /
• pp.149-157
• /
• 2016

This paper presents the traffic speed limit of heavy vehicles at each wind velocity region, which is based on their accident risk analysis under cross-wind. The variables for the accident risk analysis are overall height, overall length, intake weight, and friction coefficient of the road surface. It was confirmed from analysis results that the risk of overturning increased with higher overall height and length, and the risk of sliding decreased with higher intake weight. The risk of sliding was largest at the friction coefficient of 0.1, and the risk of overturning was lagest at friction coefficient more than 0.25. Finally, traffic speed limit was proposed by using the accident risk analysis.

• Annals of Geriatric Medicine and Research
• /
• 제21권1호
• /
• pp.17-23
• /
• 2017

Background: In at-risk older adults, gait speed is an important factor associated with quality of life and falling risk. In this study, we assessed whether therapeutic exercise could improve gait speed. Methods: We conducted a meta-analysis to evaluate the 'best' therapeutic exercise method by analyzing each exercise in terms of intensity, type, and several gait speed indices. For the analysis, we gathered 122 papers through a database search and selected 9 (n=627) that were appropriate for the meta-analysis. Results: In 8 of the 9 included papers, gait speed improved with therapeutic exercise. Usual gait speed (n=246) improved more than maximal gait speed (n=574). A resistance program was more effective than a nonresistance program for improving maximal, but not usual, gait speed. We also found that the effects of therapeutic exercise were greater in noncommunity than in community-dwelling elderly people. Conclusion: In conclusion, therapeutic exercise was effective in improving gait speed.

• 대한교통학회지
• /
• 제29권1호
• /
• pp.95-102
• /
• 2011

본 연구에서는 Solomon이 제안한 속도편차 (주행속도와 평균속도와의 차) 개념을 이용하여 주행위험도를 정립하고, 순서프로빗모형을 이용하여 주행속도선택 기반 주행위험도평가모델을 개발한다. 제안모델을 고속도로의 차내 교통안전정보 제공효과 평가실험에 적용하여, 주행위험에 미치는 다양한 요인의 효과를 분석한 결과, 다음과 같은 연구결과가 도출되었다. 첫째, 남성이 여성보다, 경력 운전자가 초보 운전자보다, 교통사고의 경험이 적은 운전자가 고속도로를 안전하게 주행할 확률이 높다. 둘째, 고속도로를 오후에 주행하는 경우, 도로표면이 젖어있는 경우, 교통량이 한산하여 서비스수준이 너무 좋은 경우 주행위험도는 증가한다. 셋째, 경사진 회전구간을 주행하는 경우와 도로연장이 긴 곡선부 구간을 주행하는 경우 주행위험도는 증가한다. 한편, 주행위험도 증가는 차내 교통안전정보를 제공함으로써 어느 정도 감소될 수 있는 것으로 나타나 차내 교통안전정보의 제공의 중요성이 확인되었다. 본 제안 모델은 새로 도입된 교통안전시설물의 교통안전도 효과를 평가 시 교통사고 자료가 부족하거나 없는 경우 교통안전도를 평가하는데 활용할 수 있다.

• 한국항해항만학회지
• /
• 제28권9호
• /
• pp.799-802
• /
• 2004

Evaluation of the quantitative risk of collision plays a key role in developing the expert system of navigation and collision avoidance. This study analysed thoroughly how to determine the threshold of avoidance sector as described in the new evaluation of collision risk, and suggested the collision risk obtained by the alteration of course and/or speed in order to pass clear qf each danger zone as the threshold of avoidance sector.

• Earthquakes and Structures
• /
• 제24권4호
• /
• pp.275-288
• /
• 2023

Based on the crucial role of high-speed railway bridges (HSRBs) in the safety of high-speed railway operations, it is an important approach to mitigate earthquake hazards by proceeding with seismic risk assessments in their whole life. Bridge seismic risk assessment, which usually evaluates the seismic performance of bridges from a probabilistic perspective, provides technical support for bridge risk management. The seismic performance of bridges is greatly affected by the degradation of material properties, therefore, material damage plays a nonnegligible role in the seismic risk assessment of the bridge. The effect of material damage is not considered in most current studies on seismic risk analysis of bridges, nevertheless. To fill the gap in this area, in this paper, a nonlinear dynamic time-history analysis has been carried out by establishing OpenSees finite element model, and a seismic vulnerability analysis is carried out based on the incremental dynamic analysis (IDA) method. On this basis, combined with the site risk analysis, the time-dependent seismic risk analysis of an offshore three-span HSRB in the whole life cycle has been conducted. The results showed that the seismic risk probabilities of both components and system of the bridge increase with the service time, and their seismic risk probabilities increase significantly in the last service period due to the degradation of the material strength, which demonstrates that the impact of durability damage should be considered when evaluating the seismic performance of bridges in the design and service period.

• 해양환경안전학회지
• /
• 제24권1호
• /
• pp.36-42
• /
• 2018

이 연구는 운항자가 항해 중 위험을 느끼는 고정 및 이동 물표에 대한 해상교통위험성평가에 대한 것이다. 이를 위해 선박 길이와 속력, 선박조종성능이 고려된 동적선박영역을 기초로 한 충돌위험평가식을 구하였다. 특히, 동적선박영역과 충돌위험평가식을 하이브리드 결합하여 자선의 크기, 속력 등의 영향을 정량적으로 지표화한 항해위험성평가모델을 검토 및 개선하고자 한 것이다. 기존 항해위험성평가 모델에 적용이 부족한 속장비(speed length ratio) 즉, 선박의 길이와 속력에 대한 비가 고려된 새로운 형태의 해상교통위험성평가 모델을 제안하고자 한다. 그 결과 무차원 속력 즉, 속장비가 클수록 CJ 값이 크며, CJ 값은 속장비에 의해 잘 표현되고 있다. 또한, 속장비가 크면 속장비가 작은 경우보다, 보다 먼 거리에서부터 [주의], [경계], [위험] 또는 [매우위험]상태에 도달한다. 이 연구의 결과는 위험항로 회피 또는 최적항로 구축, 방파제폭이나 교량경간 등을 포함한 항로나 항만개발, 연안항해용 안전해도 개발 및 향후 자율운항선박과 같은 스마트선박의 운항 중 충돌방지와 최적항로 선정에 자료로 사용될 수 있을 것이다.

• 한국도로학회논문집
• /
• 제15권1호
• /
• pp.127-134
• /
• 2013

PURPOSES: Speeding is often the primary contributor to fatal crashes. Surprisingly, driving behaviors are indirectly affected by personal factors such as law-abidance, risk sensitivity, and situational adaptability. This research aims to verify the effectiveness of pavement markings at reducing the speeds of high-risk drivers. The purpose of this study is to establish how drivers (including law-abiding or law-breaking, high-risk or low-risk) react to different pavement markings in a driving simulator. METHODS: The five different pavement markings were selected from markings used in other nations. The forty-two drivers were then surveyed, via questionnaires, and placed into the corresponding groups. Finally, statistical analysis was conducted to determine the extent of speed reduction for each pavement marking. RESULTS: Higher speeds were linked to the high-risk drivers. Furthermore, after analysis of the mean difference of average speeds by pavement marking, it was determined that Dragon's Teeth had the greatest speed reducing effect on these drivers. CONCLUSIONS: Perceptual countermeasures are unlikely to strongly affect high-risk drivers' perception of speed on the curves. This statistically demonstrates that Dragon's Teeth have a subtle effect on reducing speeds in the driving simulator. This study's significance lies in the improved understanding of high-risk drivers in terms of road facilities. It approaches the effects of various patterns of pavement markings for high-risk drivers.

• International Journal of Safety
• /
• 제9권1호
• /
• pp.47-53
• /
• 2010

The speed difference in mountainous area is known causing traffic conflicts and accidents. Thus, climbing lanes have popularly been installed in mountainous roads around the world. In the present paper, vehicle speeds within and around climbing lanes of Ho-nam and Jung-ang expressway were collected and evaluated. The evaluation was performed in terms of coefficient of variations which represent dispersion of vehicle speed in climbing lanes. Results show that speed dispersion is more significant at segments before and after climbing lanes than those within climbing lanes. The estimated accident risk was evaluated using The Solomon's u-shaped curve. It was identified that the accident risk is also a lot significant at the same segments as much as 2.2 times greater than those of climbing lanes.