Speeding is one of the principal causes of traffic accidents that harm not only the safety of pedestrians but also the driver himself and others. However, empirical studies on speeding behavior are mostly survey research and identification of cause-and-effect relationship is unclear. Also the reliability of the study results cannot be verified using retrospective methods. To complement this point, it is important to conduct an experimental study, but realworld field research using real vehicles is almost impossible to apply equally to all subjects by controlling surrounding vehicles and signal systems. Therefore, in this study, we compared the overspeed characteristics of high risk driver types using driving simulator. The high risk driver types were divided in to four types: elderly driver, commercial driver, driver with more than 10 years of driving experience, and driver within 2 years of license acquisition. The overspeed characteristics were identified by using an index called Accumulated Speeding (AS). Based on overspeed characteristics differences between driver types, it is expected that additional education by driver type will be possible in the safety education using Driving Simulator.

Demand Responsive Transport (DRT) for the disabled is a special transportation mode for people with disabilities who have difficulties in moving. DRT for the disabled is one of the most important means of transportation for people with disabilities using wheelchairs because it provides door-to-door service with vehicles equipped with wheelchair boarding facilities. The Seoul city operated DRT for the disabled for the first time in Korea in 2003 and currently operates 487 vehicles. This study compared DRT for the disabled with domestic and foreign cases and analyzed usage pattern of DRT for the disabled in Seoul for the frequency of service use and waiting time. The DRT for the disabled usage pattern in Seoul showed that the number of use of weekends was smaller than that of weekdays, and it was used most at noon by the time of day. In the case of waiting time, days except Saturday were similar. On Saturday, the traffic jam was more severe than other days, so waiting time was higher than other days. By the time of day, the waiting time was higher due to the reduction of the number of vehicles in the evening and the nighttime, not the noon which had the highest number of use. As a result of analyzing day by day in four-time zones, it was analyzed that there were spatial differences in waiting time by time zone. This study is expected to be used to reduce the waiting time of DRT for the disabled through DRT for the disabled usage pattern analysis.

Car-sharing is one of the most popular cases of a shared economy. It is a sustainable service that enhances mobility by renting shared vehicles to meet user's purpose in short-time. Car-sharing has known that it is effective in reducing ownership of passenger cars, reducing traffic congestion, and improving the environment. In Korea, a variety of car-sharing services have been launched, and since 2012, Korea Land & Housing Corporation (LH) has started to introduce HappyCar service for residents of public rental housing complexes nationwide. Public rental housing complexes have three types of complexes, one of which is complex for the low-income households. The purpose of this study is to find out the factors affecting the use of carsharing for low-income people using Poisson regression analysis with 2017 HappyCar usage data. Data including outliers was filtered and explanatory variables (age, sex, and accessibility of public transportation around rental housing complexes) were selected through correlation analysis. The results of this study are expected to be useful for analysis of carsharing low-income users' behavior, demand forecasting, and the establishment of shared transportation policies in the future.

Human umbilical cord is easy to obtain because it is discarded after birth, so that ethical issues can be avoided. Chondrogenesis studies using MSCs from bone marrow, cord blood, and adipose have indicated that TGFβ3 and BMP6 stimulate chondrogenesis. Therefore, we investigated chondrogenesis of hUC-MSCs on TGFβ3, BMP6, and combination of the two growth factors. We initiated chondrogenesis of cells by application of physical forces to form 3D cell clusters. After initiation, we designated four experimental groups for differentiation of cells, as follows: control, 10 ng/mL TGFβ3, 100 ng/mL BMP6, and the combination of 5 ng/mL TGFβ3 and 50 ng/mL BMP6. For analysis of chondrogenesis, GAG contents, mRNA expression, histological analysis and immunohistochemistry (IHC) were performed. For analysis of GAG contents, GAG assay was performed and RT-PCR was performed for determination of chondrogenic markers. Histological analysis was performed through safranin O, alcian blue, and IHC was performed using collagen type I and II. GAG contents were increased 184% by TGFβ3, 147% by BMP6, and 189% by the combination of TGFβ3 and BMP6, compared to control. The growth factors improved collagen II and aggrecan expression; in particular, TGFβ3 and BMP6 showed a synergistic effect, compared to only TGFβ3 or BMP6 treated. The results of histological and IHC analysis indicated that chondrogenic differentiation in TGFβ3 and the combination of TGFβ3 and BMP6 showed more cartilage deposition. In conclusion, TGFβ3 and BMP6 differentiated hUC-MSCs into chondrogenic clusters of the combination treatment of the two growth factors showed more efficient chondrogenic ability.