PURPOSES : This study aims to understand the characteristics of accidents involving autonomous vehicles and derive the causes of accidents from road spatial information through autonomous vehicle accident reports. METHODS : For this study, autonomous vehicle accident reports collected and managed by the CA DMV were used as data sources. In addition, spatial characteristics and geometric data for accident locations were extracted by Google maps. Based on the collected data, the study conducted general statistics, text embedding, and cross-analysis to understand the overall characteristics of autonomous vehicle accidents and their relationship with road spatial features. RESULTS : The analysis results for characteristics of autonomous vehicle accidents, applying statistical analysis and text embedding techniques, reveal that the damages caused by autonomous vehicle accidents are often minor, and approximately half of the accidents are triggered by other vehicles. It is noteworthy that accidents where autonomous vehicles are at fault are not uncommon, and when the cause of the accident is within the autonomous vehicle, the accident risk can increase. The accident analysis results using spatial data showed that the severity of accidents increases when on-street parking is present, when dedicated lanes for bicycles and buses exist, and when bus stops are present. CONCLUSIONS : Through this study, geometric and spatial elements that appear to have an impact on autonomous driving systems have been identified. The findings of this study are expected to serve as foundational data for improving the safety of autonomous vehicle operations in the future.

The interest in greenhouse gases (GHG) emitted from all industries is emerging as a very important issue worldwide. This is affecting not only the global warming, but also the environmentally friendly competitiveness of the industry. The fisheries sector is increasingly interested in greenhouse gas emissions also due to the Paris Climate Agreement in 2015. Korean industry and government are also making a number of effort to reduce greenhouse gas emissions so far, but the effort to reduce GHG in the fishery sector is insufficient compared to other fields. Especially, the investigation on the GHG emissions from Korean fisheries did not carry out extensively. The studies on GHG emissions from Korean fishery are most likely dealt with the GHG emissions by fishery classification so far. However, the forthcoming research related to GHG emissions from fisheries is needed to evaluate the GHG emission level by species to prepare the adoption of Environmental labels and declarations (ISO 14020). The purpose of this research is to investigate which degree of GHG emitted to produce the species (swimming crab and snow crab) from various fisheries. Here, we calculated the GHG emission to produce the species from the fisheries using the life cycle assessment (LCA) method. The system boundary and input parameters for each process level are defined for LCA analysis. The fuel use coefficients of the fisheries for the species are also calculated according to the fuel type. The GHG emissions from sea activities by the fisheries will be dealt with. Furthermore, the GHG emissions for producing the unit weight species and annual production are calculated by fishery classification. The results will be helpful to establish the carbon footprint of seafood in Korea.

PURPOSES : The turning movement of vehicles is directly affected by such factors as vehicle length, wheelbase, steering angle, articulated angle, and wheel steering. Therefore, it is necessary to analyze the impact of changes in each factor on the turning of the vehicle. Because a vehicle with a long body, such as an articulated bus, makes a wide turn, this study analyzes the swept path of the driving vehicle considering the specifications of the vehicle. METHODS : This study was conducted by dividing driving routes into four routes of two-lane four-way roundabouts, and the turning conditions were examined for six types (Type 1–6) that simulated actual articulated bus data. The same vehicle specifications as those of the actual articulated bus were applied to the road design simulation (AutoTURN Pro), and the width of the swept path for the articulated bus was investigated based on the wheel steering control. Using a virtual reference line for dividing the inscribed circle into lanes of the roundabout by 5°, the driving width of the swept path was measured and the angle at which the driving width was largest during driving through the turning intersection was examined. In addition, the changes in the driving width of the swept path according to the wheel steering control under the same wheel turning conditions, as well as the articulated and steering angles, were investigated. RESULTS : The driving width of the swept path for the vehicle (Type 1) with the front wheel control function being an all-wheel system was less than that of an articulated bus with the largest driving width of 15° after entering the roundabout and 15° before entering the roundabout (Type 2). Furthermore, although the specifications of the vehicles were the same, it was determined that Type 5 was superior to Type 6 after reviewing the driving width in light of changes in the steering and articulated angles. CONCLUSIONS : The results of this study are expected to contribute to the field of road design considering traffic safety when large vehicles, such as articulated buses, turn on roundabouts or curved road sections.

PURPOSES : This study was conducted to analyze the driving width of the vehicle body and off-track width of front-rear tires when a large vehicle or an articulated bus passes through a roundabout. METHODS : The driving width was measured using two methods considering the off-tracking tire and the size of the vehicle body. The test conditions of the roundabout were considered as follows: number of entry/exit sections (three-legs roundabout and four-legs roundabout), number of lanes (one lane and two lanes), driving speed (10 km/h, 20 km/h, and 30 km/h), driving trajectory (centerline and maneuver), and driving path (right turn, straight, left turn, and U-turn). The driving trajectories of large buses or articulated buses were analyzed using a road design simulation tool (AutoTURN Pro). RESULTS : Consequently, it was observed that the driving width calculated using the off-track width of the front and rear tires was lower than that analyzed for the vehicle body. The width was smaller in the case of driving in the one-lane roundabout than that in the two-lane roundabout. In particular, it was analyzed that the situation in which the turning path invades the lane appeared in left-turn (East → South) and U-turn (East → East) situations. The width was narrower in the case of driving in the one-lane roundabout than that in the two-lane roundabout. CONCLUSIONS : The study results are expected to be applied for designing roads when large buses or articulated buses are selected as design vehicles.

In supply chain, there are a variety of different uncertainties including demand, service time, lead time, and so forth. The uncertainty of demand has been commonly studied by researchers or practitioners in the field of supply chain. However, the uncertainty of upstream supply chain has also increased. A problem of uncertainty in the upstream supply chain is the fluctuation of the lead time. The stochastic lead time sometimes causes to happen so called the order crossover which is not the same sequences of the order placed and the order arrived. When the order crossover happens, ordinary inventory policies have difficult to find the optimal inventory solutions. In this research, we investigate the lead time distribution in case of the order crossover and explore the resolutions of the inventory solution with the order crossover.

PURPOSES: This study aimed to analyze traffic accidents at circular intersections, and discuss accident reduction strategies based on land use and vehicle type. METHODS : Traffic accident data from 2010 to 2014 were collected from the “traffic accident analysis system”(TAAS) data set of the Road Traffic Authority. To develop the accident rate model, a multiple linear regression model was used. Explanatory variables such as geometry and traffic volume were used to develop the models. RESULTS: The main results of the study are as follows. First, it was found that the null hypotheses that land use and vehicle type do not affect the accident rate should be rejected. Second, 16 accident rate models, which are statistically significant (with high R2 values), were developed. Finally, the area of the central island, number of speed humps, entry lane width, circulatory roadway width, bus stops, and pedestrian crossings were analyzed to determine their effect on accidents according to the type of land use and vehicle. CONCLUSIONS: Through the developed accident rate models, it was revealed that the accident factors at circular intersections changed depending on land use and vehicle type. Thus, selecting the appropriate location of bus stops for trucks, widening entry lanes for cars, and installing splitter islands and optimal lighting for motorcycles were determined to be important for reducing the accident rate. Additionally, the evaluation showed that commercial and mixed land use had a weaker effect on accidents than residential land use.

PURPOSES : In this study, the effects of installation of diagonal crosswalks on traffic flow depending on the types of intersections are analyzed. METHODS : Scrambled crosswalks have advantages in the traffic safety. Therefore, a comparative analysis of the overall average delay before and after installation of the scrambled crosswalk was conducted using VISSIM. RESULTS: The overall average delay for the scrambled crosswalk decreased when the traffic volume ratio of the major to the minor street is 1: 6 in 2-by-1 and 3-by-1 types of intersections. The scrambled crosswalk improved efficiency of traffic operation in intersections: higher traffic volume for a major street, lower traffic volume for a minor street, and longer cross-distance for a major street. CONCLUSIONS: This study can be used to determine when a scrambled crosswalk should be installed to improve operational efficiency.

PURPOSES : Because elderly drivers are more prone to becoming confused when approaching an urban intersection and thus may yield prolong judgment and decision times than non-elderly drivers, to increase the comfort and safety of the intersection environment for elderly drivers, this study applied autonomous driving tests at an urban intersection to examine their driving characteristics. METHODS: To obtain a more comprehensive understanding of driving features, this study collected drive data of non-elderly drivers and elderly drivers via an autonomous experiment using OBD2 and an eye-tracker, in addition to performing a literature review on the measured visibility range of elderly drivers at intersections. This literature review was conducted considering the general knowledge of elderly drivers having relatively reduced visibility. Additionally, as they are commonly more vulnerable, this study analyzes characteristics of elderly drivers as compared to those of non-elderly drivers. CONCLUSIONS: The results of this study can be summarized as follows: 1) the peripheral visible distance of elderly drivers is reduced as compared to that of non-elderly drivers; 2) elderly drivers approach and proceed through intersections at slower speeds than non-elderly drivers; and 3) elderly drivers yield increased driving distances when performing a right or left turn as compared to non-elderly drivers as a result of their reduced speed and acceleration and larger turning radii relative to non-elderly drivers.

PURPOSES: The goal of this study is to analyze the operational efficiencies of special roundabouts using simulated programs. METHODS: This study primarily focuses on comparing the delays and traffic flow disturbances occurring at special roundabouts. In this study, the operational efficiencies of 450 scenarios (5 roundabout types × traffic volumes × directional ratios × measures) are analyzed according to the corresponding delays and traffic flow disturbances using VISSIM and SSAM. RESULTS : The main results are as follows: 1) the Hamburger roundabouts are determined to yield the least common-type delays, 2) the amount of delays at Turbo and Flower roundabouts with respect to relatively increased right-turn-type delays, in addition to the amount of delays at the Left-turn slip-lane roundabout with respect to relatively increased left-turn-type delays, are found to be reduced as compared to the common-type delays. Lastly, common- and increased right-turn-type traffic flow disturbances at the Turbo roundabout and increased left-turntype traffic flow disturbances at the Left-turn slip-lane roundabout are determined to be the most infrequent. CONCLUSIONS: This study comparatively analyzes five roundabout types: standard, Flower, Turbo, Hamburger, and Left-turn slip-lane. The effectiveness of roundabouts can increase according to given traffic volume, directional ratio, and measure of effectiveness.

실내 공기질 관리의 중요성이 대두되면서 쾌적한 실내환경에 도움을 주는 공기청정 기능과 습도 조절 기능을 동시에 갖춘 제습기와 공기청정기가 각광받고 있다. 하지만 오랜 기간 동안 공기정화제품을 사용하게 될 시에는 필터가 오염되어 본연의 기능을 상실하게 되는 것으로 알려져 있지만 이에 대한 구체적인 연구나 보고는 드문 편이다. 이에 본 연구에서는 가정과 사무실 등에서 사용한 공기정화제품을 수거하여 주요 부위별 미생물 오염도 및 주요 오염 미생물들을 분석하였다. 그 결과, 4 종류의 공기정화제품에서 오염도가 높은 부위는 필터부위, 물이 직접 닿는 부위 및 공기가 외부로부터 직접적으로 들어오는 입구부위 등에서 미생물학적 오염도가 가장 높았다. 하지만 공기정화제품은 사용하는 환경과 조건에 따라서 미생물학적 오염도 및 오염 미생물의 성상은 각각 다르게 나타났다. 하지만 이들 공기정화제품들에는 공통적으로 Staphylococcus sp., Micrococcus sp. 그리고 Bacillus sp.의 세균과 Cladosporium sp. 및 Penicillium sp.의 진균이 공통적으로 오염되어 있는 우점종인 것으로 분석되었다.

교차로 신호계획 수립은 여러 가지 중요한 요소를 포함하고 있다. 특히 부도로의 녹색시간은 주도로를 횡단하는 보행자의 녹색시간에 영향을 받는다. 주도로의 녹색시간 또한 부도로를 횡단하는 보행자의 녹색 시간에 영향을 받지만, 도로위계상 주도로는 부도로에 비해 교통량이 많고 부도로는 비교적 차로수가 적 기 때문에 부도로의 횡단시간에 영향을 크게 받지 않는다. 그러나 부도로의 좌회전 또는 직진 교통류의 녹색시간은 최소한 주도로를 횡단하는 보행녹색시간보다 커야 한다. 이로 인해 부도로에서 진출하는 교통 량이 많지 않더라도 일정시간 이상의 녹색시간을 부여하여야 하므로 신호계획에 있어서 불필요한 시간이 발생하게 된다. 따라서 주도로의 용량이 초과되어 전체 교차로 서비스수준(LOS)은 감소하게 된다. 일반적으로 대각선횡단보도는 전체 교차로의 지체를 발생시킨다. 그러나 대각선횡단보도를 설치하게 되면 보행전용현시에서 횡단보행자를 모두 소거시킬 수 있기 때문에 위와 같은 최소녹색시간의 제약을 받 지 않고 부도로의 실제 교통량에 따라 신호계획을 수립할 수 있는 장점이 있다. 따라서 본 연구에서는 VISSIM 프로그램 분석을 통해 대각선횡단보도 설치 전․후의 평균차량지체(sec/veh)를 비교분석하였다. 분석결과를 토대로 대각선횡단보도를 설치함으로써 교차로 서비스수준(LOS)을 향상시킬 수 있는 교차로 유형과 주도로 및 ․부도로 교통량 비율을 제시하는 것을 목적으로 한다. 분석결과, 편도 2*1 교차로와 편도 3*1 교차로에서 부도로와 주도로의 교통량비가 1:6 이상일 경우 대 각선횡단보도를 설치하여도 평균차량지체가 감소하게 되는 것으로 나타났다. 즉 부도로의 교통량이 많지 않고, 주도로의 교통량이 많고 부도로보다 차로폭이 클 경우 대각선횡단보도를 설치하면 차량소통측면에 서 효과를 볼 수 있다. 본 연구의 결과는 대각선 횡단보도를 설치 시 효율적인지를 결정할 수 있는 기초결 과로 제공될 것으로 기대된다.

평면교차로의 원활한 운영에 대한 판단기준은 보통 서비스수준(LOS)을 따른다. 신호교차로는 신호주기 와 현시 조정 여부 등 처리효율에 따른 여러 변수에 대해서도 영향을 받겠지만, 주로 교통량이 증가할수 록 서비스수준 효과척도(MOE)인 평균지체시간이 대체로 증가하며 이는 극심한 교통정체로 이어지기도 한다. 우리나라는 교통 안전성과 효율성 확보를 위해 교차로 설계 지침서로써 전 건설교통부, 국토해양부 (현 국토교통부)는“평면교차로 설계지침”,“입체교차로 설계지침”,“회전교차로 설계지침” 등을 각각 발 간하고 도로설계 가이드라인으로 제시하고 있지만, 평면 신호교차로에서 입체교차로-주로 단순입체교차 -로 전환이 요구되는 사업 추진 시 고려해야할 기준은 명확히 제시된 바가 없다. 따라서 본 연구는 국외 입체교차로(grade separated intersection, overpass or underpass, interchange) 설계기준을 중심으 로 평면신호교차로에서 입체교차로로 전환기준에 대하여 검토, 분석하여 현 입체교차로 설계지침이 가지 고 있는 문제점 및 개선점을 도출하고자 하였다. 현 지침에서 제시하는 3가지 설계 기준은 (1) 도로 등급 과 교차형식 결정, (2) 교통량과 입체교차와의 관계, (3) 경제성을 고려한 입체교차로 구분할 수 있는데, 이 중 (2)와 (3)의 기준을 중심으로 문제점을 검토하고 이를 경기도 남양주시 삼패동에 소재한 평면신호 교차로인 삼패사거리에 적용하여 각 기준에 대한 적정성을 분석하였다. 2015년 현장 조사를 통해 수집된 교통량과 속도 자료를 기반으로 SYNCHRO와 VISSIM 활용 시뮬레이 션 분석을 실시하였는데, 먼저 교통 운영적인 측면인 교통량과의 관계에서 살펴본 결과 해당교차로는 2035년 기준 현 교차로 운영을 유지한다면 LOS가 FFF로 매우 저하되는 것으로 나타났으며, 이를 단순입 체로 전환한다면 2035년 단년 기준 감소된 평균지체시간을 비용으로 산정된 통행시간 절감편익이 총 공 사비용 및 유지비용과 대등한 것으로 나타나 입체교차로로의 전환이 시급히 요구되는 것으로 나타났다. 따라서 사례연구를 통해 입체교차로 전환기준 결정을 위한 주/부도로 교통량 관계로 보완하고, 경제성 분 석에 대한 개선안을 마련하는데 일조하고자 할 예정이다.

일반적으로 회전교차로의 유형은 기본유형과 특수유형으로 분류할 수 있으며 특수유형의 회전교차로는 설치형태에 따라 초소형 회전교차로, 평면형 회전교차로, 입체형 회전교차로로 구분한다.(ʻ회전교차로 설 계지침ʼ(국토교통부,2014), ʻ도로용량편람ʼ(국토해양부,2013)) 또한 행정안전부에서는 생활도로형 회전교 차로를 1차로형 회전교차로와 2차로형 회전교차로의 두 가지 유형으로 분류하였다. 생활도로형 회전교차 로란 현재까지 회전교차로로 관련된 연구를 검토해보면 주로 기본유형에 관련된 분석이 많았다. 일부 소 형 회전교차로, 생활형 회전교차로 관련 연구들도 있지만 기본유형에 해당하는 회전교차로에 대한 분석에 비해 적은 수의 연구가 진행되었다. 하지만 국내에서도 최근 교통 정온화 사업이 확산됨에 따라 기존 대 형차량의 통행이 적은 주거지역의 진입로를 회전교차로로 전환시켜 지역주민들의 안전성 확보 및 미관 향 상에도 긍정적인 효과를 거두고 있다. 따라서 이 연구에서는 교통 시뮬레이션 프로그램 VISSIM을 이용하여 생활도로형 회전교차로에서의 교 통량별 평균지체를 분석하였다. 교차로의 유형은 행정안전부에서 제시한 생활도로형 회전교차로의 설계 기준에 따라 1차로형과 2차로형으로 나누어 지체를 분석하였고 회전교차로가 아닌 비신호의 3지와 4지 교차로와 지체도를 비교하여 효과를 분석하였다. 진입 교통량은 4지교차로에서는 시간당 100대~1000대 까지 100대씩 증가시켜 분석하였고, 3지교차로는 120대~900대까지 90대씩 증가시켜 총 60개의 시나리 오가 분석하였다.(10×6) 분석결과는 기존 운영되던 비신호 교차로보다 생활도로형 회전교차로에서 평균 지체의 감소효과를 보일 것으로 예측된다. 이 연구는 특수유형의 회전교차로 중에서 특수유형 회전교차로 중에서도 생활도로형 회전교차로의 지 체를 유형별로 분석하였다. 이는 대형차량의 통행이 적은 이면도로나 주거지역의 진입로에 회전교차로 설 치하는데 적합한 기준이 될 것으로 예측된다. 나아가 다양한 유형의 회전교차로 설치 증대에 의미 있는 연구가 될 것으로 기대된다.

2010년 회전교차로 설계지침 발간 이후 국내 회전교차로의 도입이 활발히 이루어졌다. 안전행정부에 따르면 2013년까지 전국 364개의 회전교차로가 설치되었으며, 향후 2022년까지 1,592개소를 설치할 예 정이라고 밝혔다(안전행정부, 2014). 그러나 회전교차로의 경우 특징이 설치조건 및 운영특성이 명확하기 때문에 도입 가능한 교차로가 한정되어 있다. 최근 국토교통부에서는 2015년부터는 1일 15,000대 미만인 구간을 대상으로 회전교차로의 확대가 이루어질 것으로 밝힌 것도 이와 같은 맥락이라 볼 수 있다. 그러나 국내와는 달리 회전교차로가 일찍이 도입되어 왔던 미국, 유럽 등 세계 여러나라의 경우 기존에 도입되고 있던 표준적인 회전교차로에서 많은 진전이 이루어져 왔다. 2차로 회전교차로의 단점을 극복한 Turbo형 회전교차로, Flower형 회전교차로, Target형 회전교차로가 개발되었다. 또한 높은 진입교통량 으로 인한 지체증가의 문제점 해결을 위해 신호형 회전교차로가 운영되고 있다. 이 외에도 자전거 이용자 들과 진입차량의 합리적인 이용을 위한 C-Roundabout, 교통량 방향비에 따라 설치되는 햄버거형, 좌회 전 Slip-lane형 등 다양한 유형의 회전교차로가 존재한다. 이처럼 많은 유형의 회전교차로가 개발되어 왔음에도 불구하고 아직 국내에서는 표준적인 회전교차로 의 도입만이 이루어지고 있다. 이는 국내 회전교차로 도입이 최근에 이루어졌으며, 아직 정착단계에 이르 고 있기 때문이라고 할 수 있다. 그러나 정착단계 이후에 회전교차로의 운영효과를 극대화하기 위해서는 다양한 유형의 회전교차로 연구가 지속적으로 이루어져야 하며, 향후 국내 정서에 적합한 회전교차로의 개발이 이루어져야 한다. 이러한 점에 착안하여 본 연구는 다양한 특수유형의 회전교차로를 소개하며, 이 중 기존 회전교차로와 기 하구조 및 운영방식이 상이한 Target형 및 Turbine형 회전교차로의 운영효과를 분석하는데 목적이 있다.

PURPOSES : This study evaluated the feasibility of implementing protected-permissive left-turn (PPLT) signals at three-leg signalized intersections. METHODS: A three-leg signalized intersection with permissive left-turn was first selected. A VISSIM simulation model was constructed using data collected from the test site. The VISSIM network was calibrated by adjusting related parameter values in order to minimize the difference between the simulated and surveyed critical gap. The calibrated network was validated by the number of waiting left-turning vehicles per cycle. Finally, the mobility and safety measures were extracted from simulation runs in which permissive, protected left turns as well as PPLTs were realized based on diverse traffic volume scenarios. RESULTS : The mobility-related measures of effectiveness (MOEs) of the case with PPLT outperformed the other two left-turn treatment scenarios. In particular, the average waiting time per cycle for the left-turn vehicles in the case with PPLT was reduced by 30 s. The safetyrelated MOEs of the case with PPLT were somewhat higher than those in the case with protected left-turns and much higher than those in the case with permissive left-turns. CONCLUSIONS : Based on the mobility- and safety-related MOEs generated from the VISSIM simulation runs, the use of PPLT seems to be feasible at three-leg signalized intersections where the left-turn is permissive and a pedestrian signal exists at the conflicting approach. However, in order to use the PPLT in earnest, it is necessary to revise the road traffic act, traffic signs, and related manuals.

PURPOSES: This study dealt with traffic accidents occurring within roundabouts. The objective of this study was to analyze safety effect by introduction of roundabouts. METHODS: In pursuing the above, traffic accident data on roundabouts are collected and compared. For the analysis, collected data were separated as all intersection points, turning lane accident, approach lane accident by geometric design. RESULTS : Through the study results, it was found that the total accidents decreased by 55 accidents/2 year with safety effect of roundabouts. Also the result shows that accidents by point of two-lane roundabout at turning lane(0.26) and approach lane(0.27) is risky than total accidents by point(0.09). Moreover, accidents by point shows high value as diameter of a roundabout is bigger. CONCLUSIONS: When a roundabout is introduced at the intersections there are safety effects by reduction of traffic accidents.

PURPOSES : The purposes of this study are to compare the day and night characteristics and to develop the models of traffic accidents. in Rural Signalized Intersections METHODS : To develop day and night traffic accident models using the Negative Binomial Model, which was constructed for 156 signalized intersections of rural areas, through field investigations and casualty data from the National Police Agency. RESULTS : Among a total of 17 variances, the daytime traffic accident estimate models identified a total of 9 influence factors of traffic accidents. In the case of nighttime traffic accident models, 11 influence factors of traffic accidents were identified. CONCLUSIONS: By comparing the two models, it was determined that the number of main roads was an independent factor for daytime accidents. For nighttime accidents, several factors were independently involved, including the number of entrances to sub-roads, whether left turn lanes existed in major roads, the distances of pedestrian crossings to main roads and sub-roads, lighting facilities, and others. It was apparent that if the same situation arises, the probability of an accident occurring at night is higher than during the day because the speed of travel through intersections in rural areas is somewhat higher at night than during the day.