• Korean Journal of Ecology and Environment
• /
• v.33 no.4 s.92
• /
• pp.358-365
• /
• 2000

To evaluate the influences of stocking and removal of silver carp on plankton communities and physicochemical parameters, fish biomanipulation was conducted in six enclosures constructed on the coast of a hypertrophic lake during the summer of 1997. Of these, three enclosures were established for the fish-stocking experiment; one fishless enclosure used as a control and two enclosures with high and low densities of fish. The other three enclosures for the fish-removal experiment were prepared in an entirely converse process compared to that for fish stocking. The results of randomized intervention analysis (${\alpha}=0.05$) showed significant changes in several physicochemical parameters and plankton communities after fish stocking and removal. Fish stocking decreased water transparency, DO, pH and chi-a (> $40\;{\mu}m$), while increasing the concentration of nitrogen and chi-a (<$2\;{\mu}m$). However, water transparency did not increase by fish removal. Small plankton communities, such as picocyanobacteria, eukaryotic picoplankton and ciliates (<$2\;{\mu}m$) showed significant reciprocal changes after both fish treatments: increase by the presence of fish and decrease by the absence of fish. No count of large sized phytoplankton and zooplankton showed significant change in the presence of fish, while large zooplankton, Diaphanosoma, Cyclopida and nauplii were significantly increased by fish removal. Although the frequent heavy-winds and endless supply of phosphorus from the lake sediment strongly disturbed the fish behavior and enclosure management, the stocking and removal of silver carp showed an obvious reciprocal influences on plankton communities and its physico-chemical parameters in a shallow-hypertrophic lake.

• Journal of the Microelectronics and Packaging Society
• /
• v.9 no.4
• /
• pp.11-16
• /
• 2002

In this study, the dry etching characteristics of $SrBi_2Ta_2O_9$ (SBT) thin films were investigated by using ICP-RIE (inductively coupled plasma-reactive ion etching). The etching damage and degradation were analyzed with XPS (X-ray photoelectron spectroscopy) and C-V (Capacitance-Voltage) measurement. The etching rate increased with increasing the ICP power and the capacitively coupled plasma (CCP) power. The etch rate of 900$\AA$/min was obtained with 700 W of ICP power and 200 W of CCP power. The main problem of dry etching is the degradation of the ferroelectric material. The damage-free etching characteristics were obtained with the $Ar/C1_2/CHF_3$ gas mixture of 20/14/2 when the ICP power and CCP power were biased at 700 W and 200 W, respectively. The experimental results show that the dry etching process with ICP-RIE is applicable to the fabrication of the single transistor type ferroelectric memory device.

• Journal of agriculture & life science
• /
• v.45 no.2
• /
• pp.35-41
• /
• 2011

This study was carried out to investigate the relation of acid depositions and chlorophyll concentration in the Pinus thunbergii leaves. pH of throughfall in Pinus thunbergii forest was 4.20 at industrial sites, and 4.87 at urban sites. Total chlorophyll concentration in leaves were 0.5984 at industrial sites, and 0.6784 at urban sites. The average $SO_2$ concentration in air was 0.029ppm at industrial sites, and 0.011ppm at urban sites. Correlation between chlorophyll concentration in the Pinus thunbergii leaves and acid depositions was pH (r=-0.8769), ${NO_3}^-$ (r=0.6983), ${SO_4}^{2-}$ (r=0.8929), $SO_2$ (r=0.8738), and $NO_2$ (r=0.8523) (p<0.001). respectively. The estimation equation of chlorophyll concentration in the Pinus thunbergii leaf (Y) were given by Y=4.8979 + 0.7698pH + $0.8412{SO_4}^2$ + $0.8673SO_2$, + $0.8767NO_2$+ $0.8767{NO_3}^-$ ($r^2$=0.8873), which coefficients of determination was 0.88.

• Korean Journal of Mineralogy and Petrology
• /
• v.33 no.4
• /
• pp.391-405
• /
• 2020

Leaching chracteristics of Andong-dam sediment was conducted for heavy metal and nutrients. Five mixed sediment samples were prepared and leaching was conducted under aerobic and anaerobic condition for 60 days. Cd, Cu, Pb, Cr, Zn, Hg, As, Fe, Mn, phosphorus, and nitrogen were analyzed at each sampling time. The leaching rate of phosphorus was higher in anaerobic condition comparing with that of under aerobic condition. Some samples showed higher than the water-quality level IV. In case of As and Cd which showed highest contamination level in the sediment, leached concentration were 0.028 mg/L and 0.003 mg/L in maximum, respectively. The leached concentration is below than the lake water quality standard of Korea. Other heavy metals including Cu, Pb, and Cr also showed similar trend. Five step sequential extraction showed that easily extractable 1-2 step portion such as ion-exchangeable and adsorbed one was less than 10% and the most of the portion was residual. For As and Cd, the residual portion were 80% and 95% respectively indicating the risk by the heavy metal leaching into the lake for a short period was not high in comparing with the contamination levels.

• Journal of the Korean Society of Radiology
• /
• v.17 no.7
• /
• pp.1157-1164
• /
• 2023

This study measures the additional dose for each treatment area using kV X-ray based OBI (On-Board Imager) and CBCT (Cone-Beam CT), which have excellent spatial resolution and contrast, and evaluates the adequacy and stability of radiation management aspects of IGRT. The subjects of the experiment were examined with OBI and CBCT attached to a linear accelerator (Clinac IX), and ring-shaped Halcyon CBCT under imaging conditions for each treatment area, and the dose at the center was measured using an ion chamber. OBI single fraction dose was measured as 0.77 mGy in the head area, 3.04 mGy in the chest area, and 7.19 mGy in the pelvic area. The absorbed doses from the two devices, Clinac IX CBCT and Halcyon CBCT, were measured to be similar in the pelvic area, at 70.04 mGy and 70.45 mGy. and in chest CBCT, the Clinac IX absorbed dose (70.05 mGy) was higher than the Halcyon absorbed dose (21.01 mGy). The absorbed dose to the head area was also higher than that of Clinac IX (9.08 mGy) and Halcyon (5.44 mGy). In kV X-ray-based IGRT, additional radiation exposure due to photoelectric absorption may affect the overall volume of the treatment area, and caution is required.

• Korean Journal of Environmental Agriculture
• /
• v.19 no.4
• /
• pp.276-283
• /
• 2000

This study was carried out to investigate distribution of epilithic algal and chemical contents of irrigation water influencing in the Seomjin River from March to October in 1996 and 1997. In the water quality of the Seomjin River, the monthly average contents of $NH^+\;_4-N,\;SO_4\;^{2-}$ and $Cl^-$ showed the lowest peak in July and August while that of $NO_3-N$ showed the highest peak in June. The water quality of the Seomjin River was deteriorated by inflow of Yo-cheon and Sosi-cheon in the middle stream. The concentration of anions and cations of the Seomjin River was $Cl^->SO_4\;^{2-}>NO_3\;^->PO_4\;^{3-}\;and\;Ca^{2+}>Na^+>Mg^{2+}>K^+>NH_4\;^+$, respectively. The epilithic algal community identified 339 taxa consisting of 7 forma, 42 varieties and 290 species in 6 classes. In species composition, green algae and diatoms were heavily dominated which were evaluated 50.4% and 31.3% of total classification, respectively. In seasonal distribution, 219 species presented in summer but, 147 species were in winter. In this study, dominant species were Cocconeis placentula var. euglypta and Cosmarium furcatospermum in spering. Cyclotella meneghinasa and Synedra ulna, Scenedesmus ecornis in summer. Melosira varians, Achnathes minutissima in autumn and Gomphonema parvulum in winter were dominated. Finally, the dominant indices in this study have ranged 0.10-0.43.

• Korean Journal of Soil Science and Fertilizer
• /
• v.43 no.2
• /
• pp.147-152
• /
• 2010

The investigations were conducted to improve the fertilizer use in upland soil on the different topographies, and crops at 163 upland fields located in the parts of Gyengsangbuk-do area. The soil distribution was based on crops, and topographiese. Soils from these fields were analyzed for pH, organic mater, available phosphorus ($P_2O_5$), exchangeable potassium, calcium and magnesium, and found to have pH5.9, organic mater 23.2 g $kg^{-1}$, $P_2O_5$ 549 mg $kg^{-1}$, exchangeable potassium, calcium and magnesium were 0.9, 5.6, and 2.3 $cmol^+\;kg^{-1}$, respectively. The excessive distribution percent of soil samples for crops were higher than the optimum range in $P_2O_5$, and exchangeable potassium. The content of organic matter, $P_2O_5$, exchangeable potassium, calcium, and magnesium were increased with the decreasing slope. The major chemical components in fans topographies were 28.4 g $kg^{-1}$ for organic matter, 700 mg $kg^{-1}$ for $P_2O_5$, and 1.0 $cmol_c\;kg^{-1}$ for exchangeable potassium relatively higher in comparison with other topographies. The content of $P_2O_5$ were lower in diluvium, and hilly areas than other topographies. The soil of red pepper was more influenced by the amount of applied fertility than the slope, and topographies, On the other hand the crops like soybean and sesame, were more affected by the slope, and topographies.

• Journal of Bio-Environment Control
• /
• v.16 no.4
• /
• pp.407-414
• /
• 2007

In order to evaluate the physicochemical properties of sludge compost and to identify the effects water-extracts from sludge compost in 2, 6, 8, 12 weeks of decomposing process on seed germination and root elongation in cabbage, lettuce, soybean and barley plants was investigated. The content of total nitrogen in sludge compost increased slightly in 6 weeks decomposing process, and then decreased gradually. Organic matter content decreased continuously overall decomposing process. As decomposition was processing, pH of sludge compost decreased slightly, and EC increase within 6 weeks decomposing process, and then decreased. The content of nitrogen in water-extracts from sludge compost increased within 8 weeks decomposing process and decreased in 12 weeks decomposing process. The content of ammonium nitrogen was similar with that of total nitrogen, and the ratio of ammonium and nitrate increased within 8 weeks, and then decreased. Cation content and EC decreased the late of decomposing process and pH didn't change. The water-extracts from sludge compost during decomposing process inhibited seed germination and root elongation in cabbage (Brassica campestris), lettuce (Lactuca sativa), barley (Hordeum vulgare) and soybean (Glycine max). The inhibition of root elongation in cabbage was greater than that of relative seed germination, whereas relative seed germination in lettuce was more inhibit than root elongation. Relative seed germination and root elongation in soybean were inhibited slightly, but those of in barley was inhibited strongly. In this study, we would identify the effects of water-extracts from sludge compost on seed germination and root elongation was different to the species of seed. The inhibition of seed germination and root elongation treated with the water-extracts which extracted from sludge compost in the early stage of decomposing process was greater than that of in the late stage of decomposing process.

• Economic and Environmental Geology
• /
• v.38 no.4 s.173
• /
• pp.435-450
• /
• 2005

The purpose of the study is to analyze the hydrogeochemical characteristics by multivariate statistical method, to interpret the hydrogeochemical processes for the new variables calculated from principal components analysis (PCA), and to infer the groundwater flow and circulation mechanism by applying the geostatistical methods for each element and principal component. Chloride and nitrate are the most influencing components for groundwater quality, and the contents of $NO_3$ increased by the input of agricultural activities show the largest variation. The results of PCA, a multivariate statistical method, show that the first three principal components explain $73.9\%$ of the total variance. PC1 indicates the increase of dissolved ions, PC2 is related with the dissolution of carbonate minerals and nitrate contamination, and PC3 shows the effect of cation exchange process and silicate mineral dissolution. From the results of experimental semivariogram, the components of groundwater are divided into two groups: one group includes electrical conductivity (EC), Cl, Na, and $NO_3$, and the other includes $HCO_3,\;SiO_2,$ Ca, and Sr. The results for spatial distribution of groundwater components showed that EC, Cl, and Na increased with approaching the coastal line and nitrate has close relationship with the presence of agricultural land. These components are also correlated with the topographic features reflecting the groundwater recharge effect. The kriging analysis by using principal components shows that PC 1 has the different spatial distribution of Cl, Na, and EC, possibly due to the influence of pH, Ca, Sr, and $HCO_3$ for PC1. It was considered that the linear anomaly zone of PC2 in western area was caused by the dissolution of carbonate mineral. Consequently, the application of multivariate and geostatistical methods for groundwater in the study area is very useful for determining the quantitative analysis of water quality data and the characteristics of spatial distribution.

• Analytical Science and Technology
• /
• v.20 no.5
• /
• pp.383-392
• /
• 2007

The water soluble components were analyzed in the $PM_{2.5}$ fine particles collected at the 1100 site of Mt. Halla for the spring seasons between 1998 and 2004. The $PM_{2.5}$ mass concentrations were within $13.4{\pm}9.6{\sim}21.7{\pm}20.0{\mu}g/m^3$, and the concentrations of ionic components were in the order of nss-$SO{_4}^{2-}$ > $NH{_4}{^+}$ > $NO{_3}{^-}$ > $Ca^{2+}$ > $K^+$ > $Na^+$ > $Cl^-$ > $Mg^{2+}$, in which the concentration of nss-$SO{_4}^{2-}$($3.41{\pm}2.42{\mu}g/m^3$) was the highest. The concentrations of $NH{_4}{^+}$, $SO{_4}^{2-}$, and $NO{_3}{^-}$, the secondary pollutants, were respectively 0.60~1.50, 2.86~4.42, and $0.24{\sim}1.57{\mu}g/m^3$, which had occupied 88 % of the total ionic components, on the other hand, the concentrations of marine species were less than 5 %. The nss-$SO{_4}^{2-}$ showed the high correlation with $NH{_4}{^+}$, $K^+$, so that $NH{_4}{^+}$ and nss-$SO{_4}^{2-}$ might exist in the form of $(NH_4)_3H(SO_4)_2$ and $(NH_4)_2SO_4$ in fine particles. From the backward trajectory analysis, in case of high concentrations of $NH{_4}{^+}$ and nss-$SO{_4}^{2-}$ simultaneously, the air masses were originated and stagnated at the east region of China for a while, then moved into the atmosphere of Jeju. However, in case of $NO{_3}{^-}$ and nss-$Ca^{2+}$, the air masses originated at China and Siberia were moved into Jeju via the eastern China.