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Research on digital twins (DTs) in the power system field has mainly focused on implementing DTs for specific resources, while few studies on electric vehicle (EV)-based DT implementation have considered integration and interoperability between systems. This study introduces a DT-based EV system operation framework to address the aforementioned research gap. The framework implements individual EVs, charging stations, and charging station operators (CPOs) as DTs, enabling integrated operation with the power grid. The DT-based EV agent supports independent decision-making on power service participation by considering location information, distance, charging amount, spare time, and incentives. In addition, the CPO can establish an optimal incentive strategy to induce EV users to participate in grid power services. The proposed DT systems map information between EVs, charging stations, and the grid, enabling analysis and verification of the impact of participants on charging station operation, grid stability, and economic efficiency in an independent environment. The effectiveness and usability of the proposed framework were verified through a case study on an incentive-based demand response program.

Research on digital twins (DTs) in the power system field has mainly focused on implementing DTs for specific resources, while few studies on electric vehicle (EV)-based DT implementation have considered integration and interoperability between systems. This study introduces a DT-based EV system operation framework to address the aforementioned research gap. The framework implements individual EVs, charging stations, and charging station operators (CPOs) as DTs, enabling integrated operation with the power grid. The DT-based EV agent supports independent decision-making on power service participation by considering location information, distance, charging amount, spare time, and incentives. In addition, the CPO can establish an optimal incentive strategy to induce EV users to participate in grid power services. The proposed DT systems map information between EVs, charging stations, and the grid, enabling analysis and verification of the impact of participants on charging station operation, grid stability, and economic efficiency in an independent environment. The effectiveness and usability of the proposed framework were verified through a case study on an incentive-based demand response program.

This study covers the structural optimization of vertical axis wind turbines (VAWTs) that can operate reliably for long periods of time in marine environments, as well as simulation analysis to evaluate their fatigue and strain resistance. Due to the nature of the marine environment, strong wind speeds and constant wave loads are applied, and VAWTs are likely to suffer from fatigue build-up and deformation problems in the long term. In this study, detailed numerical simulations were performed using ANSYS software (2024 R2) to analyze the effects of different airfoil shapes, material choices, tip speed ratios (TSRs), and foundation types on the turbine’s stress distribution and fatigue resistance. The results showed that NACA 0030 airfoil, composite steel, and single-pile foundation performed best under TSR 1.8 conditions, with the potential to reduce strain by approximately 30% and fatigue damage by approximately 25% compared to conventional structures. With this optimized combination, it was found that maintenance costs could be significantly reduced while maintaining structural stability at sea. These results could make an important contribution to the economical and durable design of VAWTs in the future.

This study covers the structural optimization of vertical axis wind turbines (VAWTs) that can operate reliably for long periods of time in marine environments, as well as simulation analysis to evaluate their fatigue and strain resistance. Due to the nature of the marine environment, strong wind speeds and constant wave loads are applied, and VAWTs are likely to suffer from fatigue build-up and deformation problems in the long term. In this study, detailed numerical simulations were performed using ANSYS software (2024 R2) to analyze the effects of different airfoil shapes, material choices, tip speed ratios (TSRs), and foundation types on the turbine’s stress distribution and fatigue resistance. The results showed that NACA 0030 airfoil, composite steel, and single-pile foundation performed best under TSR 1.8 conditions, with the potential to reduce strain by approximately 30% and fatigue damage by approximately 25% compared to conventional structures. With this optimized combination, it was found that maintenance costs could be significantly reduced while maintaining structural stability at sea. These results could make an important contribution to the economical and durable design of VAWTs in the future.

Hydrogen fuel cell vehicles are expected to play an important role in the future and thus have improved significantly over the past years. Hydrogen fuel cell motorcycles with a small container for compressed hydrogen gas have been developed in Japan along with related regulations. As a result, national regulations have been established in Japan after discussions with Japanese motorcycle companies, stakeholders, and experts. The concept of Japanese regulations was proposed internationally, and a new international regulation on hydrogen-fueled motorcycles incorporating compressed hydrogen storage systems based on this concept are also established as United Nations Regulation No. 146. In this paper, several technical regulations on hydrogen safety specific to fuel cell motorcycles incorporating compressed hydrogen storage systems are summarized. The unique characteristics of these motorcycles, e.g., small body, light weight, and tendency to overturn easily, are considered in these regulations.

Hydrogen fuel cell vehicles are expected to play an important role in the future and thus have improved significantly over the past years. Hydrogen fuel cell motorcycles with a small container for compressed hydrogen gas have been developed in Japan along with related regulations. As a result, national regulations have been established in Japan after discussions with Japanese motorcycle companies, stakeholders, and experts. The concept of Japanese regulations was proposed internationally, and a new international regulation on hydrogen-fueled motorcycles incorporating compressed hydrogen storage systems based on this concept are also established as United Nations Regulation No. 146. In this paper, several technical regulations on hydrogen safety specific to fuel cell motorcycles incorporating compressed hydrogen storage systems are summarized. The unique characteristics of these motorcycles, e.g., small body, light weight, and tendency to overturn easily, are considered in these regulations.

The increasing burden on shipowners and shipping companies due to environmental regulations imposed by the International Maritime Organization (IMO) has led to the adoption of various compliance strategies, including the use of low-sulfur fuel, installation of scrubbers, and the use of liquefied natural gas (LNG) as an alternative fuel. LNG is particularly prevalent in dual-fuel propulsion ships, with the IMO Type C tank being the most commonly used storage facility. The structure of the IMO Type C tank comprises a pressure vessel and supporting saddles, which can be integrated or separate systems. Despite being manufactured within specified tolerances, welding-induced deformation of the tank and saddle is inevitable since the saddle is welded directly onto the hull. In integrated tank–saddle systems, this deformation can lead to cracks in the epoxy resin, which has lower strength and stiffness, as well as burn damage to the resin and wooden blocks from welding heat. In separate tank–saddle systems, installation difficulties can arise due to interference between the fuel tank system and adjacent structures, such as insulation or the fuel preparation room (FPR), resulting from saddle deformation caused by welding. This study analyzes the sensitivity of all weld lines involved in saddle installation using the direct inherent strain (DIS) method. Based on this analysis, the initial welding deformations are evaluated in relation to the welding direction and sequence. Finally, an optimized method for saddle installation is proposed to minimize deformation.

The increasing burden on shipowners and shipping companies due to environmental regulations imposed by the International Maritime Organization (IMO) has led to the adoption of various compliance strategies, including the use of low-sulfur fuel, installation of scrubbers, and the use of liquefied natural gas (LNG) as an alternative fuel. LNG is particularly prevalent in dual-fuel propulsion ships, with the IMO Type C tank being the most commonly used storage facility. The structure of the IMO Type C tank comprises a pressure vessel and supporting saddles, which can be integrated or separate systems. Despite being manufactured within specified tolerances, welding-induced deformation of the tank and saddle is inevitable since the saddle is welded directly onto the hull. In integrated tank–saddle systems, this deformation can lead to cracks in the epoxy resin, which has lower strength and stiffness, as well as burn damage to the resin and wooden blocks from welding heat. In separate tank–saddle systems, installation difficulties can arise due to interference between the fuel tank system and adjacent structures, such as insulation or the fuel preparation room (FPR), resulting from saddle deformation caused by welding. This study analyzes the sensitivity of all weld lines involved in saddle installation using the direct inherent strain (DIS) method. Based on this analysis, the initial welding deformations are evaluated in relation to the welding direction and sequence. Finally, an optimized method for saddle installation is proposed to minimize deformation.