• Journal of Microbiology and Biotechnology
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• v.17 no.7
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• pp.1139-1146
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• 2007

Cultures of Saccharomyces cerevisiae were subjected to the effect of PEF (pulse electric field) and a source of selenium. The culture period after which yeast cells were subjected to PEF treatment was optimized, as was the duration of the exposure. Optimization of the nutrient medium composition in S. cerevisiae cultures resulted in an over 1.8-fold increase in selenium accumulation with relation to cultures on the initial substrate. Optimization of the pH value and of culture duration resulted in selenium accumulation increase by approximately 78%. A significant correlation was found between the accumulation of selenium in yeast cells and its concentration in the culture substrate. The highest accumulation of selenium in the biomass of yeast, approx. $240\;{\mu}g/g$ d.m., was obtained after 15-min exposure to PEF on a 20-h culture. An approx. 50% higher content of selenium in cells was recorded, as compared with the control culture without the application of PEF.

• Fisheries and Aquatic Sciences
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• v.6 no.2
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• pp.81-87
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• 2003

Experiments were carried out to investigate the accumulation and the histopathological changes in liver of juvenile rockfish, S. schlegeli, after sub-chronic dietary Cu (0, 50, 125, 250 and 500mg/kg) exposure for 60 days. Cu accumulation in liver was significantly increased with dietary exposure period and concentration for 60 days, and has a linear relation with dietary exposure days. After 60 days of Cu dietary exposure, the Cu concentration in the liver was $75.9\pm12.05,\;126.29\pm22.11\;and\;360.44\pm45.26\;{\mu}g/g$ dry weight and was approximately 11-fold, 18-fold and 51-fold higher than in the control diet group at 125, 250 and 500 mg/kg Cu diet group. The accumulation factors were increased with the dietary exposure period in liver of rockfish. In the primary exposed stage, the effect of hepatic tissue in the rockfish exposed to dietary Cu observed enlargement of hepatocytes nuclei, activity of hepatic cells and the swelling of hepatic cells. While exposed time and concentration were increased, the distinct granulation, irregular shape and necrosis of hepatic cells were observed. It was observed that granule degeneration and necrosis showed a part of cells in hepatic tissue after 60 days at 500 mg/kg.

• Fisheries and Aquatic Sciences
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• v.6 no.4
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• pp.213-219
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• 2003

Experiments were carried out to investigate the accumulation and elimination changes in the tissue of juvenile rockfish (Sebastes schlegeli) after sub-chronic dietary Cu (0, 50, 125, 250 and 500 mg/kg) exposure for 60 days and depuration for 30 days. The profile of Cu accumulation in the tissue of rockfish was dependent on the exposure periods and Cu concentration. Liver of rockfish is a more important storage tissue than other tissues, and the order of Cu accumulation in tissues was liver > intestine > kidney > gill > muscle. The accumulation factors were increased with the exposure period in gill, intestine, liver, kidney and muscle. An inverse relationship was observed between the accumulation factor and the exposure concentrations in the gill, kidney and muscle. Cu elimination in tissues of rockfish were decreased with periods for the 30 days of depuration except kidney and muscle. The order of Cu elimination in organs during depuration was intestine > liver > gill.

• Journal of the korean society of oceanography
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• v.39 no.3
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• pp.197-206
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• 2004

Mussel, Mytilus galloprovincialis, was transplanted reciprocally between contaminated site (St. STP) and relatively less contaminated site (St. UB) in Onsan Bay, Korea in order to estimate heavy metal accumulation and release. Transplanted and indigenous mussels were collected 8 times over 108 days deployment at both sites and analyzed for Cd, Cu, Pb and Zn using ICP/MS. Cu and Zn concentration did not show any significant differences between transplanted and indigenous mussels throughout the experiment period, although dissolved Cu and Zn concentrations in seawater were significantly higher at contaminated site. Pb accumulated rapidly, while Cd did not show any accumulation in the mussels transplanted from St. UB to St. STP. These accumulation patterns might reflect the variation of dissolved metal concentration; dissolved Pb concentration was significantly higher in St. STP than St. UB, while dissolved Cd concentration was similar between both sites throughout this experiment. Release of Cd and Pb in the mussels transplanted from St. STP to St. UB was not significant during the transplantation period. The levels and variation of Pb and Cd concentrations in mussels transplanted from St. STP to St. UB were similar to those in the indigenous mussels at St. STP throughout the period. Therefore, Cd and Pb accumulated in indigenous mussels may indicate the integrated metals throughout their lives, not responding to the present status of seawater because the release of accumulated metals in mussels occurs very slowly when the seawater metal levels are lowered. On the other hand, since the transplanted mussels can respond immediately to the levels of metals in seawater, it may be suggested that the present status of heavy metals in seawater can be only acquired from the metal levels of mussels transplanted from clean environments.

• Asian Journal of Turfgrass Science
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• v.5 no.1
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• pp.47-53
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• 1991

A laboratory experiment was conducted in order to learn the effect of a number of organic matters on the ammonification and nitrification of urea, and the reaction of soil, applied to a loamy upland soil poor in orgnic matter(<1.5%, without plants 1.The ammonification of urea was most pronounced in one week period immediatly after fertilizer and water treated, after which a rapid decrease of it was followed showing no accumulation at the end of 3rd week. Owing to the accumlation of ammonium, pHs of treated soils were read 7.0 to 7.3 from 6.8~6.9. 2.Nitrification was also progressed rapidly in the first one week period so that the accumulation of NO$_3$-N surpassed that of ammonia during this period. After the 1st week the accumulation of N0$_3$-N was continuously increased showing the maximum at the end of 4 weeks following a sharp decrease at the end of 5th weeks. The accumulation of NO$_3$-N dropped soil pH from 6.8-7.0 to 6. 0-6.2,but the decrease of NO-N at the end of 5th weeks brought up soil pH to 6.4-6.6. again. 3.Amino acid fermentation byproduct rich in salt, paticularly chloride, slowed down the ammonification and nitrification of urea. 4.The application of organic matter diminished the acidifying effect of chemical fertilizers. The diminishing effect of soluble humic acid and amion acid fermentation byproduct showed greater than that of solid organic matter in this experiment, which might be own to the application of a rather small amount of water soluble organic matters. Rice straw powder among solid organic matters appeared to be the least in the diminishing effect above. It may be reasoned that these soluble organic matters decomposes rapidly so as to affect Soil pH, but solid organic matters, particularly the rice straw powder, form acidic humus.

• Environmental Engineering Research
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• v.20 no.3
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• pp.246-253
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• 2015

The effects of carbon-to-nitrogen (C/N) ratio in simulated rice straw hydrolysates using glucose and ammonium chloride on polyhydroxyalkanoates (PHA) accumulation by Cupriavidus necator was investigated. In general, PHA accumulation rate was higher under higher degrees of N-deficient conditions (e.g., C/N ratio of 360:1) than lower degrees of N-deficient conditions (e.g., C/N ratio of 3.6:1 and 36:1). Also, the most PHA accumulation was observed during the first 12 h after the PHA accumulation initiation. This study showed that the similar PHA accumulation could be achieved by using different accumulation periods depending on C/N ratios. N source presence was important for new cell production, supported by approximately ten times greater PHA accumulation under the N-deficient condition ($NH_4Cl$ 0.01 g/L) than the N-free (without $NH_4Cl$) condition after 96 h. C/N ratio of the rice straw hydrolysate was approximately 160:1, based on the glucose content, and this accumulated $0.36{\pm}0.0033g/L$ PHA with PHA content of $21{\pm}3.1%$ after 12 h. Since external C or N source addition for C/N ratio adjustment increases production cost, an appropriate accumulation period may be used for PHA accumulation from organic wastes, based on the PHA accumulation patterns observed at various C/N ratios and C and N concentrations.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.896-906
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• 2020

Wood deterioration experiments were carried out for 6 months in an intertidal zone of South Korea to monitor the changes in the chemical properties of two types of species, Korean red pine and sawtooth oak. The results of FT-IR spectra and XRD patterns have shown that the chemical properties of the wood did not change significantly during the 6-month burial period. However, the brightness of the surface decreased after burial; the value of the sawtooth oak sample was lower than that of the Korean red pine sample owing to an accumulation of inorganic compounds in cell lumen as observed by ICP analysis. Among the inorganic compounds, sodium and sulfur concentrations increased significantly over the burial period compared with the control. Further, the maximum moisture content decreased from 199% to 136% in the Korean red pine and 62% to 60% for the sawtooth oak. Nevertheless, the major chemical composition of both the wood species did not change significantly during the 6-month burial period, whereas, the crystallinity decreased with an increasing burial period owing to an accumulation of inorganic compounds in the lumen.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.349-349
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• 2023

In recent years, urban floods have become more frequent, causing significant harm to society and resulting in substantial losses to the national economy and people's lives and property. To assess the impact of floods on people's safety and property in Seoul, annual precipitation data from 1980 to 2020 was analyzed for return periods of 5, 10, 20, 50, and 100 years. A rainfall runoff simulation model for Seoul was established using HEC-HMS and HEC-RAS models. The study revealed that at a 5-year return period, water began to accumulate in Seoul, but it was not severe. However, at a 10-year return period, the water accumulation was relatively serious, and inundation began to occur. At a 20-year return period, there was serious water accumulation and inundation in Seoul. During a 50-year return period, Seoul suffered from severe inundation in commercial areas, resulting in substantial losses to the local economy. The findings indicate that Seoul City faces high flood risks, and measures should be taken to mitigate the impact of floods on the city's residents and economy.

• Journal of Environmental Health Sciences
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• v.34 no.5
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• pp.351-360
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• 2008

These experiments were conducted to determine the effects of Gamdutang on the accumulation of cadmium in the body of groups of rats that received an 8-week administration of 1.7, 3.4 and $6.8{\mu}g$/g/day of cadmium, respectively, while the other groups of rats received an 8-week administration of a mixture of cadmium by concentration and Gamdutang. A comparative analysis of these groups was conducted in respect of weight, accumulated cadmium in blood and diverse organs and pathological findings from the kidneys. As for the cadmium accumulation in blood, livers, kidneys, and testis, with the lengthening of the experiment period, the cadmium and Gamdutang mixture-administered groups tended to have reduced accumulation levels compared with the groups exclusively administered cadmium. Histopathological observation of the kidneys, observed in the cadmium exclusively administered groups showed hemorrhagic necrosis in glomeruli, swelling of tubules, epithelial shedding and necrosis of tubules; however, only mild tissue lesions were observed in the cadmium and Gamdutang mixture-administered groups. Given the above results, Gamdutang is deemed to have the effects of reducing the accumulation of cadmium in blood, liver, and testis when low-concentration cadmium is administered to rats.

• Journal of Institute of Control, Robotics and Systems
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• v.10 no.1
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• pp.96-102
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• 2004

For sensitivity enhancement, the general assisted-GPS acquisition method adopts not only the coherent accumulation technique but also the non-coherent accumulation technique since the long coherent accumulation period increases the number of frequency search cells. But the non-coherent accumulation technique causes tile squaring loss, which is a dominant factor among the acquisition losses of assisted GPS dealing with weak GPS signals. This paper derives the squaring loss of the previous assisted-GPS acquisition method and proposes an assisted-GPS acquisition method for solving the problem of squaring loss in weak signal environment. In this paper, it is explained that the proposed assisted-GPS acquisition method prevents the squaring loss using a coupled coherent accumulation technique and the number of search cells of the proposed assisted-GPS acquisition method is much smaller than that of the previous assisted-GPS acquisition method. Finally, through the simulation by the GPS simulator, the acquisition success rate of the proposed assisted-GPS acquisition method is compared with that of the previous assisted-GPS acquisition method and the acquisition improvements are shown in weak signal environment.