• Journal of the Korean Geotechnical Society
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• v.18 no.2
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• pp.137-146
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• 2002

Field piezocone dissipation tests are performed, and the results are compared to the Rowe cell consolidation tests results to investigate the consolidation characteristics of soft marine deposit at the same location in Korea. From these results, statistical formula fur the relation between the coefficients of horizontal consolidation$(c_r)$ from Rowe cell consolidation tests and $t_{50}$ from pore pressure dissipation tests by Piezocone is suggested through the regression analysis. The results are also compared to the existing theoretical formula. It is also shown that suggested formula is similar to Torstensson's(1977) formula based on cylindrical cavity expansion theory and Houlsby and Teh's(1988) formula based on strain path method.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.185-191
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• 2021

The characteristics of the foundry sand were analyzed for water jacket core required to prevent structural deformation from the heat generated in the cylinder bore during the casting of the cylinder block of an automobile. The sand core tensile strength tester, AFS-GFN, and optical microscope were used to evaluate the its properties. If the SiO2 content is high in the foundry sand, the dimensional defects and veining defects occur due to high temperature expansion. Also, if it is too low, the core breakage, porosities, chemical burn-on defects occur. The particle size index and grain shape influenced the core strength and resin consumption, resulting in fluctuations in defect types. The higher the alkalinity of the dried sand, the lower the core strength. And the more basic, the lower the core strength. At the resin content of 1.6~1.8%, the increase in core strength after 1 hour curing was approximately at its maximum.

• Explosives and Blasting
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• v.34 no.2
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• pp.31-38
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• 2016

The hydrodynamics code is a numerical tool developed for modeling high velocity impacts where the materials are assumed to behave like fluids. The hydrodynamics code is widely used for solving impact problems, such as rock blasting using explosives. For a realistic simulation of rock blasting, it is necessary to model explosives numerically so that the interaction problem between rock and explosives can be solved in a fully coupled manner. The equation of state of explosives, which describes the state of the material under given physical conditions, should be established. In this paper, we introduced the hydrodynamics code used for explosion process modeling, the equation of state of explosives, and the determination of associated parameters.

• Journal of the Korean Society of Propulsion Engineers
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• v.21 no.4
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• pp.52-62
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• 2017

The study for the performance characteristics of the nozzleless booster used in ramjet booster was carried out. Performances related to pressure and thrust for nozzleless booster are lower than classical motor those because of absence of convergent and divergent sections of nozzle. To solve this problem, it developed a high-performance propellant with maximum impulse density included Al as metal fuel. Using the nozzleless booster casted the propellant, ground test of it was carried out by varying the length-to-diameter ratio (L/D ratio) of the propellant. Specific impulse of nozzleless booster was limited to about 75 percents of its value compared with that of classical motor adapted nozzle in the same propellant and propellant length and will be estimated approximately 85 percents of its value compared with that of classical motor at same average pressure in terms of the curve fitting by our test results.