• Journal of the Korean GEO-environmental Society
• /
• v.16 no.9
• /
• pp.33-41
• /
• 2015

The vertical bearing capacity of a bucket foundation installed in sand can be calculated as sum of the skin friction and end bearing capacity. However, the current design equations are not considering the non-associated flow characteristics of sand and the reduction in the skin friction and increase in the end bearing capacity when the vertical load is applied. In this study, we perform two-dimensional axisymmetric finite element analyses following non-associated flow rule and calculate the vertical bearing capacity of circular bucket foundation of various sizes installed in sand of different friction angles. After calculating the skin friction and end bearing force at the ultimate state, design equations are derived for each. The skin friction of bucket foundation is shown significantly small compared to the end bearing capacity. Considering the difference with the available design equation for piles, it is recommended that the equation for piles is used for the bucket foundation. A new shape-depth factor ($s_q{\cdot}d_q$) for bucket foundation is recommended which also accounts for the increment of the end bearing capacity due to skin friction. Additionally, the shape and depth factor of embedded foundation proposed from the associated flow rule can overestimate the bearing capacity in sand, so it is more adequate to use the shape-depth factor proposed in this study.

• Solar Energy
• /
• v.13 no.1
• /
• pp.22-30
• /
• 1993

This Paper deals with the experimental study of the axisymmetric air jet impinging vertically on the flat heating surface with and without swirl. The purpose of this study is to investigate the characteristics of flow, augmentation of heat transfer rate, turbulent intensity, and the comparison of heat transfer rate, the optimal swirling condition about the swirl and nonswirl axisymmetric air jet. In order to augment the heat transfer on the flat heating surface without introducing any additional power, the technique used in the present work was placement of twisted tape inserted pipe in front of the nozzle exit in order to make a swirl. The effect of swirl degree is investigated in case of S=0., 0.056, 0.111, 0.222 and the velocity of the jet was 14, 20, 26, 32, 38, 44m/s. The distance between the nozle exit and the stagnation point on the impinging plate was the H/D=$1{\sim}14$. In order to analyze of the flow structure which increase heat transfer, the velocity and the turbulent intensity of the axisymmetric jet was measured by a hot wire anemometer according to the swirl number and H/D.

• Journal of the Korean Chemical Society
• /
• v.55 no.4
• /
• pp.603-611
• /
• 2011

Ethoxylacetyl oxime ligands [HL, (1) and $H_2L^1$, (3)] react with copper(II) acetate monohydrate yield octahedral and square planar complexes, respectively. The complexes have been postulated due to elemental analyses, IR, UVVis. spectra, magnetic susceptibility, conductivity and ESR spectra. Molar conductance of the complexes in DMF indicates a non-ionic character. The ESR spectra of [$(L)_2Cu(H_2O)_2$], (2) complex at room temperature and 77K are characteristic of an axial symmetry ($d_{x2-y2}$) with covalent bond character and have a large line width typical of dipolar interactions. However, [$(L^1)Cu$], (4) complex in the solid state showed spectra of marked broadening and loss of hyperfine splitting confirming spinexchange interactions between the copper(II) sites. The spectrum of the doped copper(II) complex at room temperature showed super-hyperfine splitting from coordinated nitrogen atoms and it has an axial type ($d_{x2-y2}$) with covalent bond character and an essentially square-planar arrangement around the copper(II) ion. The spectrum of [$(L^1)Cu$], (4) in frozen methanol at 77K was characteristic of the triplet state of a dimer species and the distance found between the two copper(II) centers was calculated and is equal to 4.8 ${\AA}$.