The practical application of lithium–sulfur batteries (LSBs) is limited by the shuttle effect of lithium polysulfides (LiPSs), large volume expansion, and sluggish conversion kinetics of sulfur. Herein, the crystallinity regulation of NixFey alloy anchored on oxidized carbon nanotube/nitrogen‐doped graphene (NixFey@OCNT/NG) for application of a functional separator into LSBs is demonstrated. A low crystalline NixFey@OCNT/NG (LC‐NixFey@OCNT/NG) modified polypropylene separator is systematically compared with its highly crystalline counterpart (HC‐NixFey@OCNT/NG), demonstrating superior LiPS absorbability, redox mediating capability into facilitated conversion kinetics, and uniform flux of Li+ into the anode. Furthermore, theoretical calculations confirm that the LC‐NixFey alloy features high adsorption energies and low diffusion energy barriers toward LiPSs, as well as a decreased energy gap and larger electron density near Fermi level. Accordingly, the LSB cells with LC‐NixFey@OCNT/NG modified separators deliver a high specific capacity of 1379.13 mA h g−1 at 0.1 C and a low decay ratio of 0.04%/cycle over 600 cycles at 5.0 C with a high capacity of 410 mA h g−1. Even under high sulfur loading (5.37 mg cm−2) and lean electrolyte (E/S = 4.9 µL mg−1) conditions, the LSB cells with LC‐NixFey@OCNT/NG/PP deliver a high areal capacity of 4.1 mAh cm−2 at 0.2 C.

-There is an increasing interest in research to help overcome the energy crisis that has been focused on energy storage applications in various parts of power systems. Energy storage systems are good at enhancing the reliability or improving the efficiency of a power system by creating a time gap between the generation and the consumption of power. As a contribution to the various applications of storage devices, this paper describes a novel algorithm that determines the power and storage capacity of selected energy storage devices in order to improve upon railroad system efficiency. The algorithm is also demonstrated by means of simulation studies for the Korean railroad lines now in service. A part of this novel algorithm includes the DC railroad powerflow algorithm that considers the mobility of railroad vehicles, which is necessary because the electric railroad system has a distinct distribution system where the location and power of vehicles are not fixed values. In order to derive a more accurate powerflow result, this algorithm has been designed to consider the rail voltage as well as the feeder voltage for calculating the vehicle voltage. By applying the resultant control scheme, the charging or discharging within a specific voltage boundary, energy savings and a substation voltage stabilization using storage devices are achieved at the same time.

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A newly-built inverter has to undergo a series of stress tests in the final stage of production line. This can be achieved by connecting it to a dynamometer consisting of a three-phase machine joined by a rigid shaft to a DC load machine. The latter is controlled to create some specific load characteristic needed for the test. In this paper a test method is proposed, in which no mechanical equipment is needed. The suggested test stand consists only of a inverter to be tested and a simulator converter. Both devices are connected back-to-back on the AC-side via smoothing reactors.The simulator operates in real-time as an equivalent load circuit, so that the device under test will only notice the behavior of a three-phase machine under consideration of the load. In order to prove rightness of the suggested test method, the simulation and actual experiment carried out emulation for a 2.2kW induction motor.

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The purpose of this research was to derive promising technologies for the transport of hydrogen fuel cells, thereby supporting the development of research and development policy and presenting directions for investment. We also provide researchers with information about technology that will lead the technology field in the future. Hydrogen energy, as the core of carbon neutral and green energy, is a major issue in changing the future industrial structure and national competitive advantage. In this study, we derived promising technology at the core of future hydrogen fuel cell transportation using the published US patent and paper databases (DB). We first performed text mining and data preprocessing and then discovered promising technologies through generative topographic mapping analysis. We analyzed both the patent DB and treatise DB in parallel and compared the results. As a result, two promising technologies were derived from the patent DB analysis, and five were derived from the paper DB analysis.

Smart transportation technologies are being rapidly developed for enhancing the smart grid establishment. Such technologies are mostly focused on electric vehicles. However, the electric railroad has advantages in various aspects such as facility construction and utilization over an electric vehicle. Therefore, in this paper, we introduce the train-to-grid system using the electric railroads for the smart grid, and propose a reduction method for the electricity prices. The proposed method obtains actual data from the currently operating railroad systems. Furthermore, the number of trains for charging and discharging batteries is decided by using the time-of-use price and the number of railroad operations. The electricity prices are then determined by the energy consumption calculated using the number of trains used for charging and discharging and the capacity of the energy storage system in the trains. The proposed method is simulated using real data, and its superiority is verified by comparing its electric prices with the conventional electricity prices.

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