• Korean Journal of Clinical Laboratory Science
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• v.49 no.4
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• pp.366-373
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• 2017

Urinalysis is considered to be easier and simpler than other tests. It has been known to cause no burden to patients, while offering important information on diagnosing, treating, and determining the prognoses of kidney and urinary tract diseases. Urinary sediments are usually performed by microscopic examination of centrifuged urine by technologist. The guidelines proposed by the Korean Association of External Quality Assessment Service are actually different from those actually practiced by medical institutions and taught to biomedical students in textbooks. Therefore, we verified whether different sediment preparation methods lead different test results. Specimens that tested positive from the occult blood and leukocyte esterase in the urine dipstick test were randomly selected for a microscopic examination. The differences in the urine sediment preparation affected the sediment concentrations, which influenced the cell grade and cell number per HPF. The first factor in determining the sediment concentration is the centrifugal force. Many medical institutions use 1,500 rpm as the centrifugal speed without considering the radius of the centrifuge; such a value may not be accurate for 400 G. Consequently, there were differences in urine concentrations, which influenced the results. The second factor is the amount of sediment in urine. Different amounts of the remaining supernatant led to different sediment concentration factors, again, causing different results. Furthermore, not only by using a pipette to obtain an accurate amount as stipulated, but also by roughly obtaining a drop, the microscopic examination using such a volume of sediment examined affected the results. Therefore, this study highlights the importance of standardization of urine sediment preparation procedures to promote consistency and accuracy across institutions.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.95-105
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• 2005

Generally, a modified version of limit equilibrium method can be used to evaluate a slope stability of the geosynthetic reinforced soil slopes. In most cases, resisting effects of geosynthetic reinforcement are dealt with considering an increased shear strength on the potential slip surface. However, it is not clear that the methods satisfy all three equilibrium equations. As we know, the pattern of normal stress distribution along the slip surface is the key factor in calculating the safety factor of slopes. In this study, the new slope stability analysis method in which not only reinforcing effects of geosynthetics can be considered but also all three equilibrium equations can be satisfied was proposed with assuming the normal stress distribution along the slip surface as quadratic curve with horizontal $\chi-coordinate$. A number of illustrative examples, including published slope stability analysis examples for the reinforced and unreinforced soil slopes, loading test of large scale reinforced earth wall and centrifuge model tests on the geotextile reinforced soil slopes, were analyzed. As a result, it is shown that the newly suggested method yields a relatively accurate factor of safety for the reinforced and unreinforced soil slopes.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.27-38
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• 2009

In this study, a series of 1 g shaking table model pile tests were carried out in saturated dense and loose sand to evaluate dynamic p-y curves for various conditions of flexural stiffness of a pile shaft, acceleration frequency and acceleration amplitude for input loads. Dynamic p-y backbone curve which can be applied to pseudo static analysis for saturated dense sand was proposed as a hyperbolic function by connecting the peak points of the experimental p-y curves, which corresponded to maximum soil resistances. In order to represent the backbone curve numerically, empirical equations were developed for the initial stiffness ($k_{ini}$) and the ultimate capacity ($p_u$) of soils as a function of a friction angle and a confining stress. The applicability of a p-y backbone curve was evaluated based on the centrifuge test results of other researchers cited in literature, and this suggested backbone curve was also compared with the currently available p-y curves. And also, the scaling factor ($S_F$) to account for the degradation of soil resistance according to the excess pore pressure was developed from the results of saturated loose sand.