A Method for Improvement of Mining Engineering Desi...

Jo May 10, 2024

Nowadays numerical simulation is an essential tool for stability analysis of mining engineering, and constructing a more realistic numerical model is important to ensure the accuracy and reliability of mining engineering design.

In recent years, many researchers have made significant progress in the study to quickly obtain more realistic structural elements of stopes and to apply them to production practice by performing numerical simulations of mining areas with FLAC3D. However, the model construction parts in these programs are quite difficult to use for building large and complex 3D mining models, particularly, for multi-seam and multi-boundary geological bodies.

Han Un Chol, a researcher at the Science Engineering Institute has proposed a new method of quickly converting a 3D solid model into a numerical one for stability analysis of geotechnical and mining structures by combining ANSYS, FLAC3D and SURPAC.

First, he carried out a detailed analysis of the data structure used in these three programs and presented a transformation technique between the data. Then, he converted the integrated 3D solid model made by SURPAC into a numerical model of ANSYS, and meshed it as tetrahedral elements, and consecutively, converted the meshed model of ANSYS into a grid model of FLAC3D for numerical simulation.

Finally, he applied the proposed method to numerical analysis of pillar stability in the sublevel open stopes in the target mine. It was shown that the model transformation time can be reduced to 1/50 and the accuracy of the numerical model can be increased by more than 20%.

Party for Hundred-day-old Baby and Snow-white Steam...

Jo May 9, 2024

Steamed rice cake (paeksolgi in Korean where paek means ‘white’) is named after its colour which is as white as snow. It was first introduced as paeksolgo in “Kyuhapchongso”, a book of the early nineteenth century.

Snow-white steamed rice cake reflects our people’s honesty and faithfulness. Steamed rice cake has been regarded as indispensable for several occasions like a party given to a hundred-day-old baby, the first birthday of a baby, a wedding, etc.

The custom of preparing steamed rice for hundred-day-old babies is associated with parents’ wish for them to grow up healthily and honestly like snow-white steamed rice cake.

Sharing with neighbors the dishes including steamed rice cake prepared for the day, Korean people have exchanged congratulatory remarks and shared joy with one another for good harmony and unity. Such beautiful characteristics are still being handed down.

Characteristics Improvement of Weld Joint of Low Al...

Jo May 6, 2024

To estimate the lifetime of welding joints of steam pipes working at high temperatures and high pressures is of great importance for the stability and maximum economic efficiency of steam power plants.7Long-term exposure of heat-resistant steels at high temperature leads to deterioration in the mechanical properties because of the changes in the microstructure. Alloying elements and microstructures significantly affect the heat resistance in the welds of low alloy heat resistant steel at high temperature.

In order to illustrate the changing nature of heat resistance, Ri Won Jun, a researcher at the Faculty of Materials Science and Technology, investigated the mechanical properties (ultimate strength, yield strength, elongation, hardness, etc.) of pipe materials and their welding joints with respect to the content of elements in carbides, their morphology and change in the metallic structures. Also, he conducted an experiment by using zirconium instead of vanadium for electrodes to evaluate the microstructure of deposited metal, mechanical properties at room temperature, metallic structures analysis, carbide analysis, scale resistance, short-term creep strength and long-term creep strength.

As a result, he drew the following conclusions.

First, the metallographic study showed that Zr series has less migrant tendency of the grain boundary than V series at high temperatures for a long time. And the comparison of mechanical properties with hybrid carbides showed that Zr series is superior to V series in all indices.

Second, the experiment for oxidation inclination at high temperature showed that the value of scale oxidation of Zr series is 1.4 times higher than that of V series, indicating that Zr series is more stable at high temperature.

Third, the metal deposited by the stick electrode coated with Zr has no ferrite segregation and the primary structure is refiner than that with V.