Stainless steel is used in many industrial fields due to its excellent properties such as workability, strength, ductility, and corrosion resistance, and various properties required in the manufacturing field depending on the constituent components. pump impellers used in seawater and underwater require high corrosion resistance and high rigidity to prevent corrosion and damage, so they are a representative part group to which Stainless materials are applied. Through the introduction of the CMT(Cold Metal Transfer) process, a manufacturing method through WAAM(Wire Arc Additive Manufacturing) technology, which has advantages of lower production cost and excellent fatigue strength compared to the existing casting method, is being proposed. Recently, prior research on the WAAM process has been conducted on various materials, but most of the research results published so far are focused on the DED(Direct Energy Deposition) process, and a good WAAM shape design study using austenitic stainless steel is lacking. in this study, using the CMT process, the relationship between the change in bead shape and process parameters was confirmed in the BoP(Bead on Plate) welding experiment using wire made of austenitic stainless steel STS-308.

PURPOSES: The purpose of this study is to develop a traffic accident prediction model using statistical data, to analyze child traffic accidents in school zones. Furthermore, we analyze the factors affecting child traffic accidents, as obtained from the results of the developed model. METHODS : From the literature review, we obtained data for child traffic accidents and various variables relating to road geometry and traffic safety facilities in school zones. We used these variables and data to develop a child traffic accident analysis model. The model was then developed into three types using the Limdep 9.0 statistical tool. RESULTS: As a result of the overdispersion test, the Poisson regression model was applied to all types of models with an overdispersion coefficient of close to zero. The results of the model development are as follows. The main model (all scope of analysis) was for a kindergarten, considering a local roadway, the accessibility of the roadway, the number of unsignalized intersections, and the school zones in commercial area as variables that increase traffic accidents. Sub-model typeⅠ(only the roadway connected to the main entrance) was for a kindergarten, considering a local roadway, skid resistant pavement, no-parking signs, the number of unsignalized intersections, and the number of commercial facilities as variables that increase traffic accidents. The main model and sub-model type Ⅰ showed a reduction in accidents when using forward-type traffic signals. Sub-model typeⅡ(only the roadway not connected to the main entrance) shows that the local roadway is the variable that most increases the probability of traffic accidents. However, when the roadway and walkway are separated, the probability of traffic accidents decreases significantly, by up to 90%. CONCLUSIONS: The results of this study demonstrate the need to restructure the method used to improve school zones. Moreover, the effect of various traffic safety facilities was quantitatively analyzed.

PURPOSES: The purpose of this study is to investigate factors that affect the severity of children’s traffic accidents using the ordered probit model, and to contribute to a safer road environment for children. METHODS: This study used children’s traffic accident data during the last four years in the Incheon Metropolitan area. At this point, to analyze only the direct damage caused to children, the analysis was made of accidents where the victim was under 13 years old. Data from a total of 1,110 accidents was collected. When the model was constructed, as it was judged that there could be a difference in factors affecting accident occurrence depending on the zone characteristics, the model was divided into school and non-school zones. RESULTS: The accident content (severity) is divided into four stages (fatal injury, serious injury, minor injury and injury report) to construct the order-typed probit model. For the analysis, 65 variables of 17 categories were included in the model. The statistical package STATA 13.1 was used to analyze the variables affecting the accident severity with a confidence level of 90% (α·=0.1). Consequently, a total of 15 variables were found to have a statistically significant effect on accident severity in a school zone. In contrast, a total of 22 variables were found to have a statistically significant effect on accident severity in non-school zones. Four variables (daytime, weekday, victim age, intersection) were significant in both models. CONCLUSIONS: Among the significant variables found in school zones, signal violation and type of vehicle (line bus, rent car, bus, business other vehicles) had a relatively greater effect on the accident severity than the other variables. In non-school zones, eight variables comprising daytime, head-on collision, crossing, over-speed, gender of victim (male), victim age, type of vehicle (construction machinery), driver age (50-59) were found to be significant variables. In conclusion, as well as eliminating factors that can lead to accident reductions, it is necessary to consider zone characteristics to reduce the severity of children’s accidents and promote children’s traffic safety.

PURPOSES: This study aims to contribute to a better road environment, which can result in accident reduction from two-wheeled vehicles, by analyzing factors affecting the two-wheeled vehicles’ accident severities in Incheon Metropolitan City. METHODS: In this study, the two-wheeled vehicles’ accident severity was classified into four categories (fatal injury, serious injury, minor injury, and injury report) as a dependent variable, and 97 independent variables out of 14 categories were considered to construct an ordered probit model. To determine the factors affecting accident severity, the statistical package LIMDEP was used. RESULTS: Among the variables used in the analysis, variables related to accident occurrence date (first quarter), region (8-district), accident type (passing the edge of the road of the vehicle for a pedestrian accident, fixed object collision, and overturn of vehicle-only accident), violation type (unobtained safety distance, failure to perform safe driving, violation of intersection driving, and violation of others), the type of road (at the intersection, near the intersection, at the crosswalk, near the crosswalk, etc.), gender of assailant (male), vehicle of victim (pedestrian and motorcycle), and age of victim (under 20) were found to have a statistically significant effect on the severity of the accident. CONCLUSIONS: The variables related to accident type (fixed object collision and overturn of vehicle-only accident), gender of assailant (male), and vehicle of victim (pedestrian and motorcycle) have turned out increasing the accident severity. In addition, accident occurrence for two-wheeled vehicles is more diverse and vulnerable to damage than automobile accidents. Therefore, it is time to recognize the seriousness of two-wheeled vehicle accidents and to improve the environment and systems for safe driving.

PURPOSES: The purpose of this study is to develop a crash prediction model at signalized intersections, which can capture the randomness and uncertainty of traffic accident forecasting in order to provide more precise results. METHODS: The authors propose a random parameter (RP) approach to overcome the limitation of the Count model that cannot consider the heterogeneity of the assigned locations or road sections. For the model’s development, 55 intersections located in the Daejeon metropolitan area were selected as the scope of the study, and panel data such as the number of crashes, traffic volume, and intersection geometry at each intersection were collected for the analysis. RESULTS: Based on the results of the RP negative binomial crash prediction model developed in this study, it was found that the independent variables such as the log form of average annual traffic volume, presence or absence of left-turn lanes on major roads, presence or absence of right-turn lanes on minor roads, and the number of crosswalks were statistically significant random parameters, and this showed that the variables have a heterogeneous influence on individual intersections. CONCLUSIONS : It was found that the RP model had a better fit to the data than the fixed parameters (FP) model since the RP model reflects the heterogeneity of the individual observations and captures the inconsistent and biased effects.

최근 도로에서 발생하는 교통사고가 많이 줄어들긴 하였으나, 여전히 OECD 국가 중 높은 순위를 차지 하고 있는 현실 속에서 안전한 도로환경 조성을 위하여 많은 노력이 필요하다. 이러한 노력은 차량 성능, 운전문화, 제도 개선 등 많은 부분에서 적극적인 노력이 필요하지만, 특히, 도로상에 설치된 도로안전시 설은 사고의 심각도 및 사고 발생 가능성을 낮추어 주는 역할을 하는 중요한 시설로써, 도로상에서 발생 하는 교통사고에 가장 중요한 역할을 하는 것은 부인할 수가 없다. 그리고 도로안전시설은 시대의 요구 및 변화를 수용할 수 있도록 그 기능이 향상되어야 함과 동시에 제대로 설치가 되어야 원래의 기능을 발 휘할 수 있다. 이를 위하여, 국토교통부는‘도로안전시설 설치 및 관리지침ʼ을 1995년에 제정하여, 시대의 흐름에 부 합함과 동시에 도로안전시설의 설치 및 관리를 위하여 지속적인 개정을 하고 있다. 지침의 개정은 누구나 가 인정할 수 있도록 합리적으로 정립되어야 하고, 무엇보다도 도로안전시설 본연의 기능을 제대로 발휘 할 수 있도록 하는 것이 중요하다. 본 발표에서는 도로안전시설 지침에 대한 전반적인 내용, 현재 진행 중인 몇 가지 안전시설 개정(안)의 소개와 더불어 향후 개정에 대한 방향을 제시하고자 한다.

PURPOSES : This study tries to develop the accident models of 4-legged signalized intersections in Busan Metropolitan city with random parameter in count model to understanding the factors mainly influencing on accident frequencies. METHODS: To develop the traffic accidents modeling, this study uses RP(random parameter) negative binomial model which enables to take account of heterogeneity in data. By using RP model, each intersection’s specific geometry characteristics were considered. RESULTS : By comparing the both FP(fixed parameter) and RP modeling, it was confirmed the RP model has a little higher explanation power than the FP model. Out of 17 statistically significant variables, 4 variables including traffic volumes on minor roads, pedestrian crossing on major roads, and distance of pedestrian crossing on major/minor roads are derived as having random parameters. In addition, the marginal effect and elasticity of variables are analyzed to understand the variables’impact on the likelihood of accident occurrences. CONCLUSIONS :This study shows that the uses of RP is better fitted to the accident data since each observations’specific characteristics could be considered. Thus, the methods which could consider the heterogeneity of data is recommended to analyze the relationship between accidents and affecting factors(for example, traffic safety facilities or geometrics in signalized 4-legged intersections).

해마다 도로상에서 교통사고가 22만 건 이상이 발생하고, 이로 인하여 5천여 명이 사망하고 부상자는 34만 명이 넘고 있다. 다행히 최근에는 교통사고가 감소 추세에 있지만, OECD 중 최하위에 머물고 있는 정도로 심각한 수준이다. 교통사고로 인한 사회적 비용은 연간 20조 원 이상에 달하는 등 교통사고는 인 적·물적 피해뿐만 아니라 사회·경제적으로도 막대한 손실을 초래하고 있으며, 이는 국민의 건강과 사회 복지 차원에서 가장 중대한 문제이다. 도로상의 교통사고는 사람, 도로, 차량, 제도 등 여러 가지 요인에 의해 일어나는 것이지만, 도로 구조 자체와 각종 도로교통 안전시설의 설치를 포함한 안전한 도로환경의 조성은 우선되어야 한다. 이중 도로 안전시설은 교통사고 예방 및 치명도 감소를 위해 중요한 시설이다. 도로안전시설의 적합한 설치와 관리를 위하여 국토교통부는 ʻ도로안전시설 설치 및 관리 지침ʼ을 1995 년부터 제정 운영해 오고 있으며, 새로운 기술발전에 부합하고 시설물 성능 향상을 위해서 지속적인 지침 의 개정과 관리를 해오고 있다. 이들 지침의 내용은 합리적으로 정립되어야 하며, 한편 지침의 적합한 현 장 적용이 무엇보다도 중요하다. 본 발표는 도로안전시설과 시설의 설치에 대한 관계자의 이해를 높이기 위하여 그 기본에 대해서 정리 해 보았다. 또한 합리적인 안전시설 지침 개발을 위하여 연구 방법론에 대해서 살펴보았으며, 제 ․ 개정된 지침을 적용하는 방안과 지침 개정에 따른 현장의 후속 조치방안에 대해서 논하고자 한다. 끝으로 도로안전성을 높이기 위하여 도로안전시설 관련 업무에서의 발전 방안을 제시하고자 한다.

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.

PURPOSES : The purpose of the study is to a) explore the operating speed of trucks on rural highways affected by road geometry, and thereby b) develop a predictive model for the operating speed of trucks on rural highways. METHODS: Considering that most of the existing studies have focused on cars, the current study aimed to predict the operating speed of trucks by conducting linear regression analysis on the speed data of trucks operating on the linear-curved-linear portions of the road as a single set. RESULTS: The operating speed in the plane curve portion increased with the length of the curve, and decreased with a lower vertical grade and a smaller curve radius. In the straight plane portion, the operating speed increased with a larger curve radius(upstream), and decreased with an increase in the change of the vertical grade, depending on the length of the vertical curve. CONCLUSIONS: This study developed estimation models of truck for operational speed and evaluated the degree of safety for horizontal and vertical alignments simultaneous. In order to represent whole area of the rural highway. the models should be ew-analyzed with vast data related with road alignment factor in the near future

PURPOSES : The objective was to develop the advanced method which could not explain each observation’s specific characteristic in the present negative binomial method that results in under-estimation of the standard error(t-value inflation) and affects the confidence of whole derived results. METHODS : This study dealt with traffic accidents occurring within interchange segment on highway main line with RPNB(Random Parameter Negative Binomial) method that enables to take account of heterogeneity. RESULTS : As a result, AADT and lighting installation type on the road were revealed to have random parameter and in terms of other geometric variables, all were derived as fixed parameter(same effect on every segment). Also, marginal effects were adapted to analyze the relative effects on traffic accidents. CONCLUSIONS : This study proves that RPNB method which considers each observation’s specific characteristics is better fitted to the accident data with geometrics. Thus, it is recommended that RPNB model or other methods which could consider the heterogeneity needs to be adapted in accident analysis.

온실가스 배출로 인한 지구 온난화는 인류의 생존문제와 직결되어 있다. 온실가스 배출순위 세계10위 인 우리나라에서도 문제의 심각성에 대처하고 국제적인 노력에 공조하고자 온실가스와 관련된 모든 분야 에서 배출량을 줄이기 위해 많은 노력을 하고 있다. 우리나라 온실가스 배출량의 16%를 차지하고 있는 도 로분야에서도 ʻ탄소중립형 도로 기술개발 연구단ʼ이 2011년 11월에 발족되어 도로분야에서 발생하는 온실 가스를 줄이기 위한 관련 기술 및 법/제도안을 개발하는 연구를 진행하고 있다. 건축과 도시계획분야에서 는 이미 녹색도시/탄소제로도시 등을 목표로 활발한 연구가 진행 중이지만, 상당량의 온실가스를 배출하 고 있는 도로분야에서의 노력은 미흡하였다. 도로분야에서 배출되는 온실가스를 줄이는 노력은 탄소중립 형 도로를 매개체로 하여, 궁극적으로는 한국형 녹색도로(Green Highway)를 구현하는 것으로, 이는 도 로의 미래 모습일 것이다. 본 연구단에서 정의하는 녹색도로는 ʻ에너지와 자원을 효율적으로 사용하여 온 실가스 및 오염물질의 배출을 최소화하면서 안전하고 쾌적한 이동성을 확보하는 도로ʼ이다. 녹색도로를 통해 도로의 기본기능(이동 및 안전)을 유지하면서, 도로와 관련된 전과정(계획/건설/운영/유지)에서 발 생되는 온실가스의 발생을 최소화 할 수 있도록 관리해 나가야 한다. 녹색도로를 위한 첫 번째 단계인 탄 소중립형 도로구현을 위해 활성산업부산물을 활용한 탄소흡수용 도로 재료 개발, DAC(Direct Air Capture) 기술을 활용한 도로 CO2 흡수 기술개발, LCA를 고려한 탄소저감형 도로 설계 기술개발과, 이 러한 기술들의 실용성 및 적용을 위한 투자평가 시스템 및 법/제도 정립을 위한 연구가 진행되고 있다. 이에 본 논문에서는 현재 개발 중인 기술의 범위를 살펴보고, 이를 바탕으로 도로가 앞으로 나아가야할 미래지향적인 녹색도로의 추진 및 발전 방향을 제시하고자 한다.

본 연구에서는 피로 손상된 용접이음의 피로수명 향상을 위한 방법으로 햄머피닝 처리법의 적용성을 검토하기 위하여 면외거셋 필렛 용접이음과 하중비전달형 리브 필렛 용접이음의 피로실험을 실시하였다. 본 실험에서는 면외거셋과 리브를 필렛 용접한 후 햄머피닝 처리를 하지 않은 용접그대로의 시험편, 용접후 햄머피닝 처리한 시험편, 그리고 용접그대로 시험편의 피로수명의 50% 시점에 햄머피닝 처리를 한 시험편의 피로실험을 실시하였다. 그리고 햄머피닝 처리에 의한 면외거셋과 리브 용접토우부의 형상 및 표면응력의 변화를 측정하였다. 그 결과, 햄머피닝처리에 의해 30~83MPa의 압축잔류응력이 도입 되었으며, 이로 인하여 강구조물의 제작시 용접후에 햄머피닝 처리를 실시하면 피로수명을 크게 향상 시킬 수 있을 뿐만 아니라, 이를 공용기간이 예상 피로수명의 50% 이하인 강구조물의 용접이음에 적용하여도 최소 1.3배 이상의 피로수명과 피로한계 향상효과를 기대할 수 있음을 제시하였다.

To improve fatigue strength of fillet-welded joints by hammer-peening treatment, fatigue tests were carried out on three types of longitudinal out-of-plane gusset fillet-welded joints and transverse non-load carrying cruciform rib fillet-welded joints: as-welded joints, post-weld hammer peened joints and hammer peened joints at 50% of as-welded joint’s fatigue life. From the test results, the effect of hammer-peening treatment on fatigue behavior of the fillet-welded joints were presented