Keyword Network Analysis of Domestic Research Articles for Determining Recent Trends of Hydrogen Refueling Stations

Global climate change has caused various natural disasters, which has resulted in serious damage to the society. Therefore, there has been a growing interest in utilizing eco-friendly energy sources such as hydrogen fuel. Hydrogen vehicles and infrastructures have been studied extensively. However, the research trends of hydrogen refueling stations have not been systematically analyzed using text mining with domestic research articles. The keyword network and research topics were analyzed based on the Korea Citation Index (KCI) data of the past 10 years. The analysis revealed that “hydrogen refueling station,” “fuel cell,” and “charging station” are new research keywords. Furthermore, topics such as “hydrogen storage,” “hydrogen and electric vehicle,” and “safety in hydrogen refueling station” are becoming increasingly popular. These quantitative analysis results provide an insight on the development of hydrogen infrastructure and research policy.

Deformation and damage of nuclear power station fuel elements under cyclic loading

Deformation and damage of nuclear power station fuel element shells under irradiation and cyclic loading due vibrations are studied. Constitutive equations include dependencies for a creep-damage equation with a scalar damage parameter, as well as terms for thermal and irradiation creep strains, elastic, thermal, and swelling strains. The acceleration of the creep-damage process due to cyclic variation of internal pressure is considered with a dynamic creep model, for which constitutive equations are derived using the method of asymptotic expansions and averaging over a period of cyclic loading. Stress and strain states in the fuel element shell are determined by use of an in-house finite element method creep-damage code for shells of revolution. Results show the essential variation in the initially symmetric fuel element shell form, as well as the acceleration of creep-damage processes due to the cyclic pressure.