• Journal of the Korean Geotechnical Society
• /
• 제24권12호
• /
• pp.13-22
• /
• 2008

Fourteen calibration ehamber tests were performed using one cylindrical and two tapered piles with different taper angles to investigate the changes of the bearing capacity of tapered piles with soil state and taper angle of piles. The results of calibration chamber tests show that the ultimate base resistance of tapered piles increases with increasing mean stress and relative density of soil. It also increases with increasing taper angle for medium sand, but with decreasing taper angle for dense sand. The ultimate shaft resistance of tapered piles increases as vertical and horizontal stresses, relative density and taper angle increase. Based on the results of model pile load tests, a new design method with shape factors for estimation of the bearing capacity of tapered piles is proposed considering the effect of soil state and taper angle on bearing capacity of tapered piles. In order to check the accuracy of predictions calculated using the new method, middle-scale field pile load tests were also conducted on cylindrical and tapered drilled shafts in clayey sand. Comparison of calculated values with measured ones shows that the new design method produces satisfactory predictions tor tapered piles.

• Journal of Korean Society of Disaster and Security
• /
• 제11권2호
• /
• pp.29-35
• /
• 2018

This study is an experimental comparison on the fact that the sinusoidal load, which has been used so far in the laboratory cyclic test, which is an important part of the liquefaction triggering study, is somewhat different from the phenomenon that causes the soil liquefaction during the earthquake loading. To this end, this study proposes a new type of combined sinusoidal load and compares it with experimental results to load the conventional sine wave. In the comparison, the shaking table tests were carried out and the sample in the tests was remolded with the relative density of 40%, which is a condition where liquefaction is easy to occur. Firstly, the conventional cyclic test was carried out under the condition that with the amplitude of sine wave was 0.3 g. Additionally, 3 types of tests were performed using the combination loads made up with 0.03 g sinusoidal load and 0.3g sinusoidal load. At that time, the loading time for the first sinusoidal load were changed with 5 seconds, 10 seconds, and 15 seconds. As a result, the test with the conventional sine wave and the test with the first sinusoidal loading for 5 seconds showed that the change of the pore water pressure gradually increased. But in the tests with the combined sinusoidal load which changed the first sinusoidal loading time with 10 and 15 seconds, it was found that the pore water pressure suddenly rose at a certain instant and liquefaction occurs. From the experimental comparison, it is judged that it is appropriate that the time of the first sine wave is over 10 seconds at the proposed combined load for the soil condition with relative density 40%.

• Journal of Microbiology and Biotechnology
• /
• 제18권3호
• /
• pp.477-482
• /
• 2008

A variety of bacterial strains were isolated from waste disposal sites of Uttaranchal, India, and some from artificially developed soil beds containing maleic anhydride, glucose, and small pieces of polyethylene. Primary screening of isolates was done based on their ability to utilize high- and low-density polyethylenes (HDPE/LDPE) as a primary carbon source. Thereafter, a consortium was developed using potential strains. Furthermore, a biodegradation assay was carried out in 500-ml flasks containing minimal broth (250ml) and HDPE/LDPE at 5mg/ml concentration. After incubation for two weeks, degraded samples were recovered through filtration and subsequent evaporation. Fourier transform infrared spectroscopy (FTIR) and simultaneous thermogravimetric-differential thermogravimetry-differential thermal analysis (TG-DTG-DTA) were used to analyze these samples. Results showed that consortium-treated HDPE (considered to be more inert relative to LDPE) was degraded to a greater extent (22.41% weight loss) in comparison with LDPE (21.70% weight loss), whereas, in the case of untreated samples, weight loss was more for LDPE than HDPE (4.5% and 2.5%, respectively) at $400^{\circ}C$. Therefore, this study suggests that polyethylene could be degraded by utilizing microbial consortia in an eco-friendly manner.

• The Korean Journal of Quaternary Research
• /
• 제18권2호통권23호
• /
• pp.3-3
• /
• 2004

One short core with length of 146cm(HB-107, at coordinates of $N51^{\circ}$11'37.5";$E100^{\circ}$24'45.6", from 229m water depth was subject of the present study. The sub-samples of the core were analyzed for the water contents (WC%), biogenic silica, identification of the main phases, grain size distribution, geochemistry and some physical properties of sediment(Wet density and Magnetic susceptibility) with aims of recording palaeo-environmental changes in Northem Mongolia. The evaluation of the geochemical and mineralogical proxies on palaeo-climated and palaeo-environmental changes are based on comparison to the behvior of biogenic silica through core, as later one had been showed itself, as good indicator of the climate and environmental fluctuation. Age model of the investigating core based on previously C 14 dated core HB105 taken from the central part of the Hobsgol Lake and the result had been published elsewhere. The core consists of two litological varieties : upper diatomaceous silt, lower clay. According to the age model the upper diatomaceous silt formed during the Holocene, lower caly-during the late Pleistocene glacial period. The geochemistry and phase identification analysis on the core samples are resulted in determining main minerals that form the bottom sediments and their geochemistry. The main include quartz, felspar, muscovite, clinochlore, amphibole and carbonate phase(dolomite and calcite). Through the core not only occur the relative quantitative changes of the main phases, but also happen that the carbonate phase completely disappear in diatomaceous silt. This is believed to be related to the lake water salinity changes, which occurred during the trassition period from Pleistocene glacial-to the Holocene interglacial. These abrupt changes of the mineralogy have been clearly traced in geochemistry of sediments, specially in calcium concentration, which is high in lower clay and low in upper diatomaceous silt. That means, geochemistry and mineralogy of the bottom sediments can be used as proxy data on palaeo-climate and palaeo-environmental changes.

• Journal of Ecology and Environment
• /
• 제36권4호
• /
• pp.255-265
• /
• 2013

This study was conducted to determine the extent of drought resistance based on physiological responses of Calystegia soldanella under water deficit. In order to investigate the changes of plant growth, stomatal density, photosynthesis, chlorophyll fluorescence, the contents of chlorophyll and carotenoid, osmolality, total ion contents, the contents of carbohydrate and proline, C. soldanella was grown under well watered and drought stressed conditions for 12 days. In this study, water-deficit resulted in remarkable growth inhibition of C. soldanella. The effect of water-deficit on plant growth was associated with low osmotic potential of soil. On day 12 after drought treatment, dry weight, relative water contents, number and area of leaves and stem length were lower than those of control. The stomatal conductance and net photosynthetic rate were significantly reduced in water stressed plant to regulate inner water contents and $CO_2$ exchange through the stomatal pore. Chlorophyll fluorescence and chlorophyll contents were not different in comparison with the control, indicating that the efficiency of photosystem II was not affected by drought stress. This results could be explained that water-deficit in C. soldanella limits the photosynthetic rate and reduces the plant's ability to convert energy to biomass. A significant increase in total ion contents and osmolality was observed on day 7 and day 12. Accumulation of proline in leaves is associated with the osmotic adjustment in C. soldanella to soil water-deficit. Consequently, this increase in osmolality in water stressed plant can be a result in the increase of ion contents and proline.

• Asian Pacific Journal of Cancer Prevention
• /
• 제16권15호
• /
• pp.6407-6412
• /
• 2015

Purpose: To predict prostatic carcinoma using a logistic regression model on prebiopsy peripheral blood samples. Materials and Methods: Data of a total of 873 patients who consulted Urology Outpatient Clinics of Fatih Sultan Mehmet Training and Research Hospital between February 2008 and April 2014 scheduled for prostate biopsy were screened retrospectively. PSA levels, prostate volumes, prebiopsy whole blood cell counts, neutrophil and platelet counts, neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), biopsy results and Gleason scores in patients who had established diagnosis of prostate cancer (PCa) were evaluated. Results: This study was performed on a total of 873 cases, with an age range 48-76 years, divided into three groups as for biopsy results. with diagnoses of benign prostatic hyperplasia (BPH) (n=304, 34.8 %), PCa (n=265, 30.4 %) and histological prostatitis (n=304; 34.8 %). Intra- and intergroup comparative evaluations were performed. White blood cell and neutrophil counts in the histological prostatitis group were significantly higher than those of the BPH and PCa groups (p=0.001; p=0.004; p<0.01). A statistically significant intergroup difference was found for PLR (p=0.041; p<0.05) but not lymphocyte count (p>0.05). According to pairwise comparisons, PLR were significantly higher in the PCa group relative to BPH group (p=0.018, p<0.05, respectively). Though not statistically significant, higher PLR in cases with PCa in comparison with the prostatitis group was remarkable (p=0.067, and p>0.05, respectively). Conclusions: Meta-analyses showed that in patients with PSA levels over 4 ng/ml, positive predictive value of PSA is only 25 percent. Therefore, novel markers which can both detect clinically significant prostate cancer, and also prevent unnecessary biopsies are needed. Relevant to this issue in addition to PSA density, velocity, and PCA3, various markers have been analyzed. In the present study, PLR were found to be the additional predictor of prostatic carcinoma.

• Journal of the Korean Geotechnical Society
• /
• 제20권6호
• /
• pp.137-150
• /
• 2004

Aging effect of sands showed insignificant result in comparison with that of clay, so that it has not been studied so far. But, as penetration resistance increase has been observed with the lapse of time after deposition and disturbance, aging effect of sands has been actively investigated by field tests, and recently many researchers are performing not oかy field tests but also laboratory tests on sands, so aging effects of sands have been also examined by laboratory tests. In this study, to observe the aging effect of undrained static shear behavior for Nak-Dong River sand, undrained static triaxial tests were performed with changing relative density$(D_r)$, consolidation stress ratio$(K_c)$, and consolidation time. These tests showed that modulus within elastic section increased as consolidation time increased, and in addition, phase transformation point strength$(S_{PT})$ and critical stress ratio point strength $(S_{CSR})$ also increased. But pore water pressure ratio$(u/{p_c}')$ decreased as consolidation time increased, so with this various result, aging effect of static shear for sands can be observed as well.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• 제19권1호
• /
• pp.44-51
• /
• 2005

In this paper, reduction characteristics of the AC and DC flashover voltage in the horizontal air gap of sphere-sphere electrode system were investigated when the combustion flame was present near the high voltage electrode. The voltage and current waveforms were measured, when the flashover is occurred, in order to examine the flashover polarity by flame. The reduction characteristics of AC flashover voltage were discussed with the thermal ionization process, the relative air density and the deflection phenomena in the shape of flames that caused by the coulomb's force. As the results of an experimental investigation, It was found that the reduction of flashover voltages in sphere-sphere system, in comparison with the no flame case, are $79.9[\%]$ for k=0, $82.9[\%]$ for k=0.5, $87.5[\%]$ for k=1.0, $85.0[\%]$ for h=0[cm], $40.8[\%]$ for h=5[cm] and $28.2[\%]$ for h=9[cm] when ac voltage is applied. The influence for thermal ionization process of the combustion flame in small scale no particular change is recognized.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• 제44권1호
• /
• pp.71-77
• /
• 2011

The effects of temperature, light, and salinity on the growth of Costaria costata and Undaria pinnatifida juveniles were examined in laboratory cultures. In a cultivation farm, the monthly yield and density were also investigated between December and April for C. costata and between December and March in 2007 and 2008 for U. pinnatifida. The relative growth rates (RGRs) were greater at $20{\sim}60\;{\mu}mol$ photons $m^{-2}s^{-1}$ than at low ($0{\sim}10\;{\mu}mol$ photons $m^{-2}s^{-1}$) and high ($100{\sim}180\;{\mu}mol$ photons $m^{-2}s^{-1}$) irradiance levels. The optimal growth conditions for the two species were $17^{\circ}C$, 35 psu, $60\;{\mu}mol$ photons $m^{-2}s^{-1}$, and a daylength of 12 h, indicating that C. costata and U. pinnatifida have very similar growth responses to temperature, light, and salinity. However, the growth responses of the two species to various environmental factors were different; C. costata grew faster than U. pinnatifida but the latter species grew well at low salinity. The monthly yield of C. costata and U. pinnatifida increased steadily over the study period, and it was maximal in March for both species, but the yield of U. pinnatifida was greater than that of C. costata.

• Journal of Powder Materials
• /
• 제23권2호
• /
• pp.95-101
• /
• 2016

Carbon nanofiber (CNF) composites coated with spindle-shaped $Fe_2O_3$ nanoparticles (NPs) are fabricated by a combination of an electrospinning method and a hydrothermal method, and their morphological, structural, and chemical properties are measured by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. For comparison, CNFs and spindle-shaped $Fe_2O_3$ NPs are prepared by either an electrospinning method or a hydrothermal method, respectively. Dye-sensitized solar cells (DSSCs) fabricated with the composites exhibit enhanced open circuit voltage (0.70 V), short-circuit current density ($12.82mA/cm^2$), fill factor (61.30%), and power conversion efficiency (5.52%) compared to those of the CNFs (0.66 V, $11.61mA/cm^2$, 51.96%, and 3.97%) and spindle-shaped $Fe_2O_3$ NPs (0.67 V, $11.45mA/cm^2$, 50.17%, and 3.86%). This performance improvement can be attributed to a synergistic effect of a superb catalytic reaction of spindle-shaped $Fe_2O_3$ NPs and efficient charge transfer relative to the one-dimensional nanostructure of the CNFs. Therefore, spindle-shaped $Fe_2O_3$-NP-coated CNF composites may be proposed as a potential alternative material for low-cost counter electrodes in DSSCs.