• 한국기계가공학회지
• /
• 제7권4호
• /
• pp.115-120
• /
• 2008

The fatalities of pedestrian accounted for about 40.0% of all fatalities in Korea (2005 year). In pedestrian involved accident, the most important data to inspect accident is throw distance of pedestrian. The throw distance of pedestrian can be influenced by many variables, such as vehicular frontal shape, vehicular impact speed, the offset of impact point, the height of pedestrian, and road condition. The trajectory of pedestrian after collision can be influenced by vehicular frontal shape classified into sedan type, box type, SUV type and van type. Many studies have been done about pedestrian accident with passenger car model and bus model for simple factors. But the study of pedestrian accident by van type vehicle was much insufficient, and even that the influence of multiple factors such as the offset of impact point was neglected. In this paper, a series of pedestrian kinetic simulation were conducted to inspect relationship between throw distance and multiple factors with using PC-CRASH s/w, a kinetic analysis program for a traffic accident for van type. By based on the simulation results, multi-variate regression was conducted, and regression equation was presented.

• 한국도로학회논문집
• /
• 제15권2호
• /
• pp.131-138
• /
• 2013

PURPOSES : The intents of the study are to identify the accident factors and to demonstrate the potentials of tobit model as a tool to study the number of accidents on arterial roads segments. METHODS : This paper uses a tobit regression as a methodology to analyze the factors affecting the number of accidents. In pursuing the above goal, this study gives particular attentions to analyzing the data of 2,446 accidents (1,610 in major arterial roads and 836 in minor arterial roads) occurred on arterial roads in 2007 to 2010. RESULTS : First, 3 accident models which were classified by total arterial roads, major arterial roads and minor arterial roads, and were all statistically significant were developed. Second, the exclusive right-turn lane as common variable, and the number of accident, traffic volume, number of lanes, link length, rate of median, number of entrances, number of pedestrian crossings, number of curves, number of bus stops and exclusive left-turn as specific variables of the models were selected. Finally, the paired sample t-test could not be rejected the null hypotheses of three types of models. CONCLUSIONS : Using data from vehicle accidents on arterial roads, the estimation results show that many factors related to roadway geometrics and traffic characteristics significantly affect to the number of accidents.

• 한국도로학회논문집
• /
• 제11권4호
• /
• pp.1-7
• /
• 2009

고령화가 진행될수록 고령운전자의 수 역시 증가될 것으로 예상되어 향후 고령운전자에 의한 교통사고는 급증할 것으로 판단된다. 본 연구는 고속도로 교통사고 발생시 고령층과 비고령층의 구분에 따른 교통사고 특성을 분석하였다. 분석결과 비고령층에 비해 고령층에 작용하는 영향요인이 다르게 나타남을 알 수 있었다. 로짓모형을 통해 비고령층과 고령층의 Odds Ratio를 분석하여 사고영향요인에 따른 차이점을 알아보았으며 고령운전자의 사고 분석 모형을 개발하였다. 비고령층에 비해 곡선구간 및 절토구간, 노면의 습기상태일 때 고령운전자의 사고위험이 높은 것으로 나타났다.

• Nuclear Engineering and Technology
• /
• 제51권3호
• /
• pp.723-730
• /
• 2019

Acquiring instrumentation signals generated from nuclear power plants (NPPs) is essential to maintain nuclear reactor integrity or to mitigate an abnormal state under normal operating conditions or severe accident circumstances. However, various safety-critical instrumentation signals from NPPs cannot be accurately measured on account of instrument degradation or failure under severe accident circumstances. Reactor vessel (RV) water level, which is an accident monitoring variable directly related to reactor cooling and prevention of core exposure, was predicted by applying a few signals to deep neural networks (DNNs) during severe accidents in NPPs. Signal data were obtained by simulating the postulated loss-of-coolant accidents at hot- and cold-legs, and steam generator tube rupture using modular accident analysis program code as actual NPP accidents rarely happen. To optimize the DNN model for RV water level prediction, a genetic algorithm was used to select the numbers of hidden layers and nodes. The proposed DNN model had a small root mean square error for RV water level prediction, and performed better than the cascaded fuzzy neural network model of the previous study. Consequently, the DNN model is considered to perform well enough to provide supporting information on the RV water level to operators.

• 한국도로학회논문집
• /
• 제17권5호
• /
• pp.39-46
• /
• 2015

PURPOSES: The operational characteristics of roundabouts are generally influenced by location as well as traffic volume. The goal of this study is to develop urban and rural roundabout accident models and to discuss safety improvement guidelines based on the model. METHODS : To analyze accidents, count data models are utilized in this study. This study used accident data from 2010 to 2013 for 56 roundabouts collected from the Traffic Accident Analysis System (TASS) of Road Traffic Authority. Poisson and negative binomial regression models were developed for this study using NLOGIT 4.0. RESULTS : The main results are as follows. First, the hypotheses that there are distributional differences in the number of accidents and injuries/fatalities among rural and urban roundabouts were accepted. Second, Poisson and negative binomial regression accident models, which were all statistically significant, were developed. Seven independent variables, which were statistically significant, were adopted. Third, the common variable of models was evaluated to be traffic volume. CONCLUSIONS : This study developed two negative binomial roundabout accident models and suggested some accident reduction strategies. The results are expected to give some implications to the safety improvement of roundabout.

• 한국ITS학회 논문지
• /
• 제19권5호
• /
• pp.1-14
• /
• 2020

본 연구는 고속도로 교통사고의 사고차량대수에 따른 요인의 영향을 분석하기 위해 다항로짓모형을 이용하여 연구를 수행하였다. 기존의 교통사고 심각도 연구에서는 사고차량대수에 대한 분석이 미흡하였다. 그러나 다중추돌사고는 인명피해 사고로 이어질 가능성이 높고, 사고 지속시간과 사고처리를 위한 사회적 비용이 크기 때문에, 다중추돌사고에 영향을 미치는 요인을 파악하는 것이 중요하다. 따라서 본 연구에서는 사고차량대수를 사고의 요인이 아닌 사고의 결과로 해석하고, 이에 미치는 사고요인별 영향을 분석하였다. 분석결과, 야간사고와 고속도로 본선, 터널, 교량에서 발생한 사고, 운전자과실, 도로장애물, 노면문제로 인한 사고, 내리막 경사, 중차량 연관 사고가 다중추돌사고로 이어질 가능성이 높은 것으로 분석되었다.

• Nuclear Engineering and Technology
• /
• 제55권3호
• /
• pp.999-1008
• /
• 2023

Deformed fuel rods can cause a partial blockage of the flow area in a subchannel. Such flow blockage will influence the core coolant flow and further the core heat transfer during the reflooding phase and subsequent severe accidents. Nevertheless, most of the system analysis codes simulate the accident process based on the assumed flow blockage ratio, resulting in inconsistencies between simulated results and actual conditions. This paper aims to study the influence of flow blockage in severe accident scenario of the CAP1400 reactor. First, the flow blockage model of ISAA code is improved based on the FRTMB module. Then, the ISAA-FRTMB coupling system is adopted to model and calculate the QUENCH-LOCA-0 experiment. The correctness and validity of the flow blockage model are verified by comparing the peak cladding temperature. Finally, the DVI Line-SBLOCA accident is induced to analyze the influence of flow blockage on subsequent CAP1400 reactor core heat transfer and core degradation. From the results of the DVI Line-SBLOCA accident analysis, it can be concluded that the blockage ratio is in the range of 40%-60%, and the position of severe blockage is the same as that of cladding rupture. The blockage reduces the circulation area of the core coolant, which in turn impacts the heat exchange between the core and the coolant, leading to the early failure and collapse of some core assemblies and accelerating the core degradation process.

• 대한교통학회지
• /
• 제23권6호
• /
• pp.103-113
• /
• 2005

교통사고 중 차대보행자 사고의 원인분석은 차대차 사고에 비해 관련 연구가 미흡한 실정이다. 국내에서도 차대차 사고의 경우에는 실차충돌실험을 통해 많은 자료를 축척하고 이를 체계화하여 다각적인 방법으로 실제 교통사고에 적용하려는 노력이 있으나 차대보행자 사고의 경우에는 아직 시작단계라고 볼 수 있다. 선진국에서는 차대보행자 사고에 대하여 더미를 이용한 실차충돌실험을 통해 많은 모형을 개발하였고, 이를 보행자사고의 정확한 원인분석을 위해 활용하고 있다. 국내에서는 차대보행자 사고의 해석과 관련된 모형이 개발되지 않아 외국의 모형을 그대로 활용하는 것이 일반적이다. 그러나 외국의 모형을 이용하게 되면 차량과 보행자의 체위특성이 다른 경우 왜곡된 결과가 도출될 가능성이 많게 된다. 이러한 문제점을 해결하기 위해 본 연구에서는 그 동안 수집된 보행자 사고자료를 이용하여 국내 실정에 적합한 차대보행자 충돌모형을 개발하였다. 그 결과 차량의 속도에 따라 외국의 모형과는 다소 상이한 결과를 보이는 것으로 나타났다. 외국의 모형 중에서는 차량 및 보행자의 체위 특성이 유사한 일본의 모형과 가장 흡사한 것으로 나타났다. 이 연구 결과는 수십개의 자료를 이용한 것으로 장래에 보다 폭넓은 자료를 통하여 모형의 신뢰성을 높이는 노력이 필요하다고 판단된다.

• 한국항해항만학회지
• /
• 제35권4호
• /
• pp.281-287
• /
• 2011

According to the Marine Traffic Safety Law, revised in 2009, Marine Traffic Safety Audit is introduced to secure the safe navigation, to prevent the marine accident and to maximize the efficiency of the port. In this audit system, marine traffic safety assessment is the most important scheme because the primary purpose of the audit system is to identify potential risk elements affecting safe navigation. Even though the reliability of audit result depends on the selection of assessment models, there are no independent assessment models for Korean coastal waters and most of models used in Korea currently are developed by foreign countries. Therefore, the development of the independent assessment model for Korean coastal water is required. This study, prior to the development of independent assessment model, aims to provide a basic data by comparing two foreign assessment models in Ulsan port area with marine accident statistics data.

• 한국안전학회지
• /
• 제28권6호
• /
• pp.84-89
• /
• 2013

The main causes of traffic accidents can be classified by 3 factors - human error, vehicle deficiency and road environmental problem and most accidents occurs not only 1 factor but combination of 2 or 3-factors. Among these factors, road environmental factor is the most important factor due to influence the behavior of cars and road users and road environmental factor affects 30% of total accidents approximately. The 5 years traffic accidents data analyzed to verify the accidents severity on Korea National Highways. In order to analyze the severity, Ordered Probit Model was used. As a independent variables of this model the number of lane, neighbor road environments, sight distance, vertical grade, lane width, shoulder width and traffic volume were used and as a dependent variables the minor injuries, serious injuries and fatalities were used. Research results shows that sight distance and lane width are identified as significant factors for the traffic accident severity and lesser sight distance and lane width shows greater traffic accident severity.