• KEPCO Journal on Electric Power and Energy
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• v.6 no.3
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• pp.315-319
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• 2020

The modern transportation and mobility sector is expected to encounter high penetration of Electric Vehicles (EVs) because EVs contribute to reducing the harmful emissions from fossil fuel-powered vehicles. With the prospective growth of EVs, sufficient and convenient facilities for fast charging are crucial toward satisfying the EVs' quick charging demand during their trip. Therefore, the Fast Electric Vehicle Charging Stations (FECS) will be a similar role to gas stations. In this paper, we study a charging scheduling problem for the FECS with solar photovoltaic (PV) and an Energy Storage System (ESS). We formulate an optimization problem that minimizes the operational costs of FECS. There are two cost and one revenue terms that are buying cost from main grid power, ESS degradation cost, and revenue from the charging fee of the EVs. Simulation results show that the proposed scheduling algorithm reduces the daily operational cost by effectively using solar PV and ESS.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.2
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• pp.222-227
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• 2015

This paper presents the optimal energy generation systems for economical EVs(Electric Vehicles) charging stations located in an island area. The system includes grid electricity, diesel generator and renewable energy sources of wind turbines and PV(Photovoltaic) panels. The independent generation system is designed with data resources such as annual average wind speed, solar radiation and the grid electricity price by calculating system cost under different structures. This sensitive analysis on the varying data resources allows for the configuration of the most economical generation system for charging stations by comparing initial capital, operating cost, NPC(Net Present Cost) and COE(Cost of Energy). Depending on the increase of the grid cost, the NPC variation of the most economical system which includes renewable energy generations and grid electricity can be smaller than those of other generation systems.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.4
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• pp.356-361
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• 2019

Since the government announced the roadmap to revitalize the hydrogen economy, we are constantly making the effort to expand the use of fuel cell electric vehicles (FCEV) and hydrogen charging stations. There is however a significant issue to build and operate the hydrogen charging station due to the lack of the profit model. Many researchers believe that the supply of FCEV will be increased in the near future and finally ensure the economy of hydrogen charging stations. This study shows that the sales changes of hydrogen gas and consumption patterns by the operation of the hydrogen charging station in Changwon City. The results will be used as the evidence to support for operating the hydrogen charging station by private businesses and the validity of additional establishment of hydrogen charging stations.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.44 no.2
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• pp.1-14
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• 2021

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.

• Korean Chemical Engineering Research
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• v.58 no.4
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• pp.573-580
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• 2020

Hydrogen emerged as a sustainable transport energy source. To increase hydrogen utilization, hydrogen refueling stations must be available in many places. However, this requires large-scale financial investment. This paper proposed a methodology for selecting the optimal location to maximize the use of hydrogen charging stations. The location of gas stations and natural gas charging stations, which are competing energy sources, was first considered, and the expected charging demand of hydrogen cars was calculated by further reflecting data such as population, number of registered vehicles, etc. Using k-medoids clustering, one of the machine learning techniques, the optimal location of hydrogen charging stations to meet demand was calculated. The applicability of the proposed method was illustrated in a numerical case of Seoul. Data-based methods, such as this methodology, could contribute to constructing efficient hydrogen economic systems by increasing the speed of hydrogen distribution in the future.

• Journal of the Korean Society of Safety
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• v.34 no.4
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• pp.6-14
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• 2019

There are about 38,977 CNG cars and 247 natural gas vehicle charging stations in operation in order to improve the urban air environment. With the introduction of natural gas vehicles, the atmospheric environment, which was the main cause of air pollution in the metropolitan area, was remarkably improved. However, unlike these positive effects, CNG bus accidents, which occurred more than 10 times since 2005, have caused concern among the majority of citizens using public transportation. It is necessary to make a judgment on the feasibility and future direction of CNG pressure vessel safety management that can safeguard the safety of CNG pressure vessel at the time of starting. In this study, we investigates production and use of CNG vessel, the current status of safety management of CNG bus transportation companies & charging stations and then proposes measures to prevent accident recurrence and safety management based on the actual situation investigation and analysis.

• Transactions of the Korean hydrogen and new energy society
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• v.33 no.5
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• pp.463-469
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• 2022

After reviewing the current status of hydrogen buses and hydrogen charging stations in the United States, as well as related laws and programs, it was found that the federal and state governments supported the supports of hydrogen buses and the deployment of hydrogen charging infrastructure through various policies and programs. In order to promote the spread of domestic and overseas hydrogen buses and hydrogen charging infrastructure, it is necessary to develop and apply various legal systems and programs that can provide incentives to hydrogen bus manufacturers, hydrogen charging station installers, hydrogen bus operating organizations and entities. It is necessary to develop and apply various legal systems and programs that can provide incentives to hydrogen bus manufacturers, hydrogen charging station installers, hydrogen bus operating organizations and entities.

• Journal of Internet Computing and Services
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• v.24 no.2
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• pp.47-56
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• 2023

Hydrogen energy is an eco-friendly energy that produces heat and electricity with high energy efficiency and does not emit harmful substances such as greenhouse gases and fine dust. In particular, smart hydrogen energy is an economical, sustainable, and safe future smart hydrogen energy service, which means a service that stably operates based on 'data' by digitally integrating hydrogen energy infrastructure. In this paper, in order to implement a data-based hydrogen charging station demand forecasting model, three hydrogen charging stations (Chuncheon, Sokcho, Pyeongchang) installed in Gangwon-do were selected, supply and demand data of hydrogen charging stations were secured, and 7 machine learning and deep learning algorithms were used. was selected to learn a model with a total of 27 types of input data (weather data + demand for hydrogen charging stations), and the model was evaluated with root mean square error (RMSE). Through this, this paper proposes a machine learning-based hydrogen charging station energy demand prediction model for optimal hydrogen energy supply and demand.

• Journal of the Korean Institute of Gas
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• v.22 no.1
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• pp.53-59
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• 2018

In Korea, The number of installed LPG Charging stations is about 2000, increasing by 26 every year. In these, about 500 charging stations are older above 15 year, accounting about 25% of total stations. About 86% of them are located in the city, which is causing serious damage if accident occurs. In this paper, we developed a duel gas sensor module and integrated control system software that can prevent and correspondence to gas leaks and fire accidents at LPG/CNG charging stations. The dual type sensor module has the function of collecting and transmitting the measured data to the sensors of methane, butane and hydrogen through RF433Mhz communication. In addition, each sensor is attached with two to improve stability and accuracy. The integrated control system software detects real-time data of the devices measured by the sensors and it send to the PC and smart phone of manager. Therefore, if accident occurs, the manager can check the status of the charging station regardless of time and place.

• Journal of Korean Society of Transportation
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• v.35 no.3
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• pp.210-219
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• 2017

Electric vehicles, which are attracting attention as eco-friendly vehicles, have been increasing in number since 2011 in Korea. The purpose of this study is to analyze the efficient operation of existing charging stations and factors to consider when installing additional charging stations based on the case of Jeju Island where the electric vehicle penetration rate is high and the charging infrastructure is relatively well established. The characteristics of using electric car charging stations by region, type of facility, and time of day are analyzed. As a result of analyzing the frequency of using the charger installed in Jeju Island, the utilization of both the fast charger and the slow charger is found to be concentrated in a specific area. The usage rate of charger installed in a business facility and a public parking lot is high in both fast charger and slow charger. However, according to the usage rate by time of day, the fast charger has a high utilization rate throughout the afternoon, while the use of a slow charger is concentrated in the morning. In order to enable users to utilize the electric vehicle charging station efficiently, it is necessary to provide a publicity guide for the charging station having a low utilization rate, a notice for using the charger, and a notification of completion of charging. Considering the charging demand, the area where the charger is not yet installed should be considered as the area to install the charger, and in addition, the additional installation should be considered in the area and the facility where the amount of charge is large. Service improvement is expected to be possible by utilizing actual electric vehicle charging behavior analysis result.