In the evaluation of crashworthiness of roadside safety features, full-scale impact tests are generally required according to the established test protocols. Since the tests are expensive, it is useful to predict the crash responses of a vehicle from the other size test vehicles. This concept was used in the Manual for Assessing Safety Hardware (MASH) of American Association of State Highway and Transportation Officials (AASHTO) to decide whether mid-size vehicle tests are necessary for an attenuator system design in addition to the small car and pickup truck tests. The general applicability of this procedure in the estimation of impact responses of one vehicle from the tested vehicle is studied using the crash test data of 11 crash cushions tested by the Korea Expressway Corporation Research Institute (KECRI). Each of the 11 crash cushions has two sets of test data from 1.3 and 0.9 ton vehicles tested with an impact speed of 80 or 100 km/h depending on the class of each system. Using the procedure, for each of the 11 systems, 1.3 ton crash data were transformed into the 0.9 ton crash data, then the estimated 0.9 ton crash data were compared with the 0.9 ton test data. It was found that the crash data predictions deviated from the test data, leading to overly conservative estimation of safety risk factors. The procedure was also found inapplicable in estimating crash data of a large vehicle (1.3 ton) from the test data of a small vehicle (0.9 ton). New procedure to estimate the crash data of a vehicle from the test vehicle regardless of their relative mass size was developed and the method was validated using the crash test data of 11 different crash cushions. In the new procedure developed, pivoting the velocity trace of test vehicle was utilised. The new procedure showed favourable results in estimating the crash data of a small vehicle (0.9 ton) from the crash data of a large test vehicle (1.3 ton). It can also be applied in reverse case estimation where the predicting vehicle (1.3 ton) was larger than the test vehicle (0.9 ton).

Two-dimensional (2D) materials and their heterostructures are promising for next-generation optoelectronics, spintronics, valleytronics, and electronics. Despite recent progress in various growth studies of 2D materials, mechanical exfoliation of flakes is still the most common method to obtain high-quality 2D materials because precisely controlling material growth and synthesizing a single domain during the growth process of 2D materials, for the desired shape and quality, is challenging. Here, we report the nucleation and growth behaviors of monolayer MoS2 by sulfurizing a faceted monoclinic MoO2 crystal. The MoS2 layers nucleated at the thickness steps of the MoO2 crystal and grew epitaxially with crystalline correlation to the MoO2 surface. The epitaxially grown MoS2 layer expands outwardly on the SiO2 substrate, resulting in a monolayer single-crystal film, despite multiple nucleations of MoS2 layers on the MoO2 surface owing to several thickness steps. Although the photoluminescence of MoS2 is quenched owing to efficient charge transfer between MoS2 and metallic MoO2, the MoS2 stretched out to the SiO2 substrate shows a high carrier mobility of (15 cm2 V–1 s–1), indicating that a high-quality monolayer MoS2 film can be grown using the MoO2 crystal as a seed and precursor. Our work shows a method to grow high-quality MoS2 using a faceted MoO2 crystal and provides a deeper understanding of the nucleation and growth of 2D materials on a step-like surface.

Satisfying the large car impact condition of the high level SB5-B for "SMART Highway" longitudinal barriers, the possibility of increase of the small car impact velocity from 120km/h to 130km/h was investigated. Through computer simulation using input parameters calibrated to full-scale crash test results, various longitudinal semi-rigid barrier models were improved such that for the small car impact speed of 120km/h the change of longitudinal and transverse velocities of the impact vehicle can satisfy the  limit. The barrier model determined through this process satisfied the performance assessment criteria for SB5-B impact conditions. Varying the wing angle of slip block-outs of the passed barrier model, the possibility of increase of the small car impact velocity was investigated by FEA and a full-scale crash test was conducted. It has been shown that the possibility to increase the small car impact speed to 130km/h is high if the test facility condition for 130km/h impact velocity is better equipped.

It is possible to set up the Roadside Barrier which is suitable for Performance Evaluation Criteria by domestic standard. But a number of section of expressway roadside have old guardrail that was installed before reform the guideline. These poor performance guardrails threaten driver s life. There is lots of difficult problem to change old guardrails that are installed 2,777km in expressway of whole road side at the same time. Especially budget problem. The purpose of study is to develop performance improvement guardrails by the minimum reinforcement. In this study, guardrail improvement method(SB1, 3, 5 grade) is developed through crash simulation using LS-DYNA 3D and vehicle crash test. And it's expected not only to decrease of collision accident but to increase safe level. Of course one thing that can t be missing is to reduce a lot of budget of guardrail change.