PURPOSES : This study is conducted to evaluate the development of materials for extinguishing ESS(Energy Storage System) fires in electric vehicles using industrial byproducts. METHODS : Grout containing an appropriate amount of fly ash, silica fume, blast furnace slag powder, and ferronikel slag, which are industrial byproducts, was prepared. The fluidity, stress, and mechanical properties were evaluated in accordance with standard test methods. RESULTS : The fluidity of the materials used for the evolution of ESS fires differed depending on the material of the industrial byproducts. In the case of blast furnace slag, its fluidity is low owing to viscosity even when it content is high, and the use of ferronikelsrag is shown to be suitable for the evolution of ESS fires in fluidity and curing tests. CONCLUSIONS : Fire-extinguishing materials using industrial byproducts require a long curing time but exhibit the fluidity required for ESS fire extinguishment. In particular, the curing and fluidity of Peronikel slag and fly ash are suitable for ESS fire extinguishing.

It is highly challenging to measure the efficiency of electric vehicle charging stations (EVCSs) because factors affecting operational characteristics of EVCSs are time-varying in practice. For the efficiency measurement, environmental factors around the EVCSs can be considered because such factors affect charging behaviors of electric vehicle drivers, resulting in variations of accessibility and attractiveness for the EVCSs. Considering dynamics of the factors, this paper examines the technical efficiency of 622 electric vehicle charging stations in Seoul using data envelopment analysis (DEA). The DEA is formulated as a multi-period output-oriented constant return to scale model. Five inputs including floating population, number of nearby EVCSs, average distance of nearby EVCSs, traffic volume and traffic congestion are considered and the charging frequency of EVCSs is used as the output. The result of efficiency measurement shows that not many EVCSs has most of charging demand at certain periods of time, while the others are facing with anemic charging demand. Tobit regression analyses show that the traffic congestion negatively affects the efficiency of EVCSs, while the traffic volume and the number of nearby EVCSs are positive factors improving the efficiency around EVCSs. We draw some notable characteristics of efficient EVCSs by comparing means of the inputs related to the groups classified by K-means clustering algorithm. This analysis presents that efficient EVCSs can be generally characterized with the high number of nearby EVCSs and low level of the traffic congestion.

Evaluating the operational efficiency of electric vehicle charging stations (EVCSs) is important to understand charging network evolution and the charging behavior of electric vehicle users. However, aggregation of efficiency performance metrics poses a significant challenge to practitioners and researchers. In general, the operational efficiency of EVCSs can be measured as a complicated function of various factors with multiple criteria. Such a complex aspect of managing EVCSs becomes one of the challenging issues to measure their operational efficiency. Considering the difficulty in the efficiency measurement, this paper suggests a way to measure the operational efficiency of EVCSs based on data envelopment analysis (DEA). The DEA model is formulated as constant returns of output-oriented model with five types of inputs, four of them are the numbers of floating population and nearby charging stations, distance of nearby charging stations and traffic volume as desirable inputs and the other is the traffic speed in congestion as undesirable one. Meanwhile, the output is given by the charging frequency of EVCSs in a day. Using real-world data obtained from reliable sources, we suggest operational efficiencies of EVCSs in Seoul and discuss implications on the development of electric vehicle charging network. The result of efficiency measurement shows that most of EVCSs in Seoul are inefficient, while some districts (Nowon-gu, Dongdaemun-gu, Dongjak-gu, Songpa-gu, Guro-gu) have relatively more efficient EVCSs than the others.

In this study, the deformation of friction stir welding on the aluminum battery housing material(AL6063-T5) applied to the electric vehicle was effectively predicted through experiments and numerical simulations. The temperature data were measured during the friction stir welding experiment, and the numerical simulation was carried out using the experimental temperature data. In the heat transfer analysis, the temperature distribution of the structure over time was calculated using the Reynolds equation. The final friction stir welding deformation was calculated by performing the structural analysis using the calculated temperature distribution data over time. The thermal elasto-plastic analysis was performed according to the friction stir welding process conditions and the welding sequences. Finally, the optimum welding condition was derived that the welding speed is 1000 mm/min and the rotation speed of the tool is 2000 RPM.

Excellent plastic moldings is possible through optimization of many molding parameters. In particular, the deformation of a plastic part is affected by various factors during molding. Therefore, it is very important to select the optimum molding conditions that minimize the deformation of the molded part. Experimental design is used to select optimal molding conditions. In this study, the molding conditions were selected to minimize the deformation of the electric plastic plug of the electric vehicle using the Taguchi method in the experimental design method. Using the Taguchi Method, we found that the deformation of the plug moldings was reduced by about 7.2% compared to before optimization.

This research has been conducted to design upright parts of hand-made vehicles with the purpose of reducing material and machining cost while ensuring structural safety. Aluminum knuckles were modelled with three parts in order to enhance design flexibility as well as to reduce CNC machining cost. A vehicle model was constructed in CAD program and simulated in ADAMS View in order to estimate joint forces developing during 20 degree step steering condition at 60km/h. The joint forces obtained in the vehicle dynamics simulation were used for the structural analysis in ANSYS and dimensions of knuckle parts were adjusted until the lowest safety factor reached 2.0. The weight of knuckle decreased by 50% compared to the previous version that was designed without the structural analysis. The overall manufacturing cost decreased by 33% due to the reduction in the material as well as the CNC machining effort.

In South Korea, Jeju Island has a role as a test bed for electric vehicles (EVs). All conventional cars on the island are supposed to be replaced with EVs by 2030. Accordingly, how to effectively set up EV charging stations (EVCSs) that can charge EVs is an urgent research issue. In this paper, we present a case study on planning the locations of EVCS for Jeju Island, South Korea. The objective is to determine where EVCSs to be installed so as to balance the load of EVCSs while satisfying demands. For a public service with EVCSs by some government or non-profit organization, load balancing between EVCS locations may be one of major measures to evaluate or publicize the associated service network. Nevertheless, this measure has not been receiving much attention in the related literature. Thus, we consider the measure as a constraint and an objective in a mixed integer programming model. The model also considers the maximum allowed distance that drivers would detour to recharge their EV instead of using the shortest path to their destination. To solve the problem effectively, we develop a heuristic algorithm. With the proposed heuristic algorithm, a variety of numerical analysis is conducted to identify effects of the maximum allowed detour distance and the tightness of budget for installing EVCSs. From the analysis, we discuss the effects and draw practical implications.

Since the so-called diesel gates of German automobiles, interest in environmentally-friendly vehicles has been rising, among other alternatives, hydrogen-fueled electric vehicles with 0% vehicle emissions are expected to replace a significant portion of passenger cars. Here, we analyze trends of US, Europe, PCT (WO) 3-patent offices application of hydrogen-fueled electric vehicles and analyze the patent application trends of national and individual companies, the patent application trend of detailed technology through clustering analysis, technology competitiveness. The global market for hydrogen-fueled electric vehicles, which is currently only 0.01% of other alternatives, is expected to grow to several percent in 2020. Major automobile makers such as Japan, United States of America, Germany, and Korea continue to fiercely compete for eco-friendly vehicles.

Recently, as demand for Electric Car has been increasing, it has been a main factor that maximizing performance and ensuring the stability of the Electric Car battery to increase the reliability of Electric Car. Above all the study on thermal control in a big influence on the performance and battery life is growing in parallel. This study has compared cooling effect of an Electric Car battery between battery with Heat Sink and without Heat Sink for optimum design of Electric Car battery. Battery is simply modeled into four cells, divided into two cases of battery with Heat Sink that attached on the cell's side and without Heat Sink. And this research was conducted on forced convection. The battery which is designed by this way was numerically analyzed by CFX 14.5. Numerical results, revealed that the battery with Heat Sink was superior in terms of cooling effect. According to the numerical analysis by battery cell's temperature variations, the battery with Heat Sink turned out to be superior in cooling effect to the battery without Heat Sink.

현재 스마트폰을 비롯하여 전기자동차(EV), 드론, ESS(Energy Storage System) 등 여러 번 충·방전이 가능한 리튬이차전지가 들어가지 않는 첨단기기를 찾아보기 어려운 상황이다. 이와 같이 이차전지 시장이 크게 성장함에 따라 효용 만료, 폐기 등을 통해 폐배터리의 형태로 그 배출 또한 급증하고 있어 관리체계가 구축될 필요가 있다. 리튬이차전지는 기존 전지 대비 에너지 밀도가 3배 정도 높고 무게가 가벼워 널리 활용되고 있으나, 폭발 위험이 있어 안전 측면에서 관리가 필요하다. 해외 각국에서는 리튬이차전지 시장이 급속히 확대됨에 따라 향후 발생할 폐배터리의 배출에 대비하여 친환경적인 자원회수 및 유해물질 관리 등을 통하여 폐배터리가 환경에 미칠 영향을 최소화하고 원재료를 대체해나가고 있다. 미국의 경우, 연방법 ｢Mercury-Containing and Rechargeable Battery Management Act｣하에 폐리튬이차전지를 관리하고 있다. 유럽연합(EU) 역시 ｢Battery Directive｣를 통하여 폐배터리를 관리하고 있으며, 생산자책임제도에 기초하여 수거 및 재활용 체계를 구축하고 있다. 한편, 국내의 경우 ｢자원의 절약과 재활용 촉진에 관한 법률｣에 따라 생산자책임재활용제도(EPR)제도를 통하여 니켈카드뮴전지 등 폐배터리를 관리하고 있으나, 리튬이차전지는 포함되어 있지 않다. 또한 전기차 폐배터리(보조금 지급대상)의 경우 ｢대기환경보전법｣에 따라 지자체에 반납하도록 하고 있으나, 이후 관리체계가 부재한 상황이다. 이에, 본 연구에서는 전기차 폐배터리를 대상으로 배출-수거-자원회수-활용에 이르기까지 각 단계별 관리체계를 마련하고 자원순환성을 제고하기 위한 방안을 검토하였다.