• Nuclear Engineering and Technology
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• v.53 no.1
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• pp.188-198
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• 2021

A modern approach to nuclear energy involves reprocessing like transmutations of spent nuclear fuel products to reduce their radiotoxicity and time needed for their storage. For this purpose, they are immobilized in inert matrices made of zirconia and can be "burned" in fast neutron reactor or Accelerator Driven System. These matrices in spherical form can be obtained by sol-gel process. The paper presents a method of microspheres fabrication based on the combined Complex Sol-Gel Process and double extraction process consisting in the preparation of zirconium-ascorbate sol and simultaneous extraction of water and nitrates. The procedure allows obtaining gel microspheres with a diameter of 50 ㎛, which after heat treatment are processed into the final product. The synthesis of zirconia microspheres with Yttrium by internal gelation process is well known for over a decade now. However, the explanation and characterization of synthesis of such material by extraction of water process is rarely found. Parameters such as: pH, viscosity, shape, sphericity and crystal structure have been determined for synthesized products and semi-products. In addition, preliminary research consisting in irradiation of the obtained materials in fast and thermal neutron flux was carried out. The obtained results are presented and described in this work.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.551-557
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• 2024

Hydrogen is a renewable energy source with various characteristics such as clean, carbon-free and high-energy, and is internationally recognized as a "future energy". With the rapid development of the hydrogen energy industry, more hydrogen infrastructure is needed to meet the demand for hydrogen. However, hydrogen infrastructure accidents have been occurring frequently, hindering the development of the hydrogen industry. HyRAM+, developed by Sandia National Laboratories, is a software toolkit that integrates data and methods related to hydrogen safety assessments for various storage applications, including hydrogen refueling stations. HyRAM+'s physics mode simulates hydrogen leak results depending on the hydrogen refueling station components, graphing gas plume dispersion, jet frame temperature and trajectory, and radiative heat flux. In this paper, hydrogen leakage data was extracted from a hydrogen refueling station in Samcheok, Gangwon-do, using HyRAM+ software. A hydrogen leakage simulator was developed using data extracted from HyRAM+. It was implemented as a dashboard that shows the data generated by the simulator using a database and Grafana.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.4
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• pp.457-463
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• 2012

Current refrigerators are designed to have thin doors and walls to facilitate user convenience and increase inner storage space. However, the thin doors and walls gives rise to the problem of dew generation on the outer surface of a refrigerator due to a large critical temperature difference between the outer wall and the room air; So far, an electric heater is commonly used for making the dew to evaporate; in this case, the heater inevitably requires additional electrical power. We propose a new approach to reduce the dew generation in a refrigerator by redesigning the gasket and varying the thickness of the inner case of the refrigerator. The results of simulations performed in this study indicate that the surface temperature in the region where dew was generated was increased by approximately $0.39{\sim}3.07^{\circ}C$ without the use of a heater.

• Fire Science and Engineering
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• v.31 no.3
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• pp.1-10
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• 2017

This study examined the risk of accidents when handling hazardous materials in hazardous materials storage facilities without safety facilities. In the case of illegal dangerous cargo containers, the burning rate is very fast in the case of fire, which leads to explosions, that are damaging and difficult to control. In addition, accidents that occur in flammable liquid hazardous materials are caused mostly by accidents that occur in the space due to leakage. Therefore, the variables that affect these accidents were derived and the influence of these variables was investigated. Numerical and computational fluid dynamics programs were used to obtain the following final results. First, when a flammable liquid leaks into a specific space, it is influenced by temperature and relative humidity until a certain concentration (lower limit of combustion) is reached. In the case of temperature, it was found that the reaching time was shorter than the flash point In addition, the effect of variables on pool fire accidents of leakage tanks is somewhat different, but the variables that have the largest influence are the wind speed. Therefore, it is expected that the results of this study will be used as basic data for similar numerical analysis and it will provide useful numerical information about the accidental leakage of hazardous materials under various research conditions.