• Journal of Korean Society of Environmental Engineers
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• v.28 no.11
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• pp.1180-1185
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• 2006

Lab-scale batch experiments using several 25-L transparent acrylic reactors were conducted to develop optimum capping materials that can reduce phosphorus released from polluted sediments. The sediment used in the experiment was very fine clay(8.8 $\Phi$ in mean grain size), and organic carbon($C_{org}$) content was as high as 2%. Four kinds of batches with different capping materials Brucite($Mg(OH)_2$), Sea sand($SiO_2$), Granular-gypsum($CaSO_4{\cdot}2H_2O$), Double layer(brucite+sand), and one control batch were operated for 30 days. Phosphorus fluxes released from bottom sediments in the control batch were estimated to be 14.6 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, while 9.5 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, 5.2 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, 4.2 $mg{\cdot}m^{-2}{\cdot}d^{-1}$, and 3.1 $mg{\cdot}m^{-2}{\cdot}d^{-1}$ in the batch capped with Sea sand, Granular-gypsum, Double layer, and Brucite, respectively. The results obtained from lab-scale batch experiments show that there were 70% reduction of phosphorus for some materials such as Brucite, Double layer(brucite+sand), and whereas sea sand only about 35%. The pH range of surface sediment to which Brucite was applied showed about $8.0{\sim}9.5$ in the weak alkaline state. This effect can prevent liberation of $H_2O$. The addition of gypsum into the sediment can reduce the progress of methanogenesis because of fast early diagenesis and sufficient supply of $SO_4^{2-}$ to the sediments, stimulate the SRB highly. Therefore, the application of Brucite and Gypsum can reduce phosphorus release from the sediment as a result of formation of $Mg_5(OH)(PO_4)_3$, pyrite($FeS_x$), and apatite-mineral.

• Korean Journal of Soil Science and Fertilizer
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• v.31 no.1
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• pp.51-55
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• 1998

The experiment was conducted to elucidate the growth response of rice seedling to heavy metals, copper and zinc. The copper and zinc concentration in rice seedling was 50mg/l and 100mg/l, respectively. Germination. chlorophyll and organic compounds were investigated in seedling of rice with or without heavy metals. Root growth and germination were inhibited at 50mg/l Cu and at 100mg/l compared to control and such reduction in growth was more remarkable at 100mg/l Zn than at 50mg/l Cu. Chlorophyll content was slightly reduced at both 50mg/l Cu and 100mg/l Zn. Malic acid was remarkably increased at 50mg/l Cu compared with that at Zn 100mg/l regardless of rice cultivars. The content of organic acids such as succinic, citric, and malic acid and free proline was increased with treatment of copper and zinc.

• Korean Journal of Environmental Biology
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• v.36 no.3
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• pp.385-391
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• 2018

Toxic assessment of PBDEs (BDE-47, BDE-209) has carried out using the rates of population growth in marine phytoplankton, Skeletonema costatum. The population growth rate (r) in S. costatum was determined after 96 hours of exposure to BDE-47 (2,2'4,4'-Tetrabromodiphenyl ether) and BDE-209 (2,2', 4,4'-Decabromodiphenyl ether). It was observed that r-value in the controls (absence PBDEs) was greater than 0.04 and further a decrease was observed in a dose-dependent manner. BDE-47 reduced population growth rate in a dose-dependent manner and a significant reduction occurred at a concentration greater than $0.31mgL^{-1}$, but BDE-209 had no effect on population growth rate even at concentrations greater than $125mgL^{-1}$. The population growth rate in the presence of BDE-47 and BDE-209, $EC_{50}$ values were $0.55mgL^{-1}$ and >$125mgL^{-1}$, and NOEC values were $0.16mgL^{-1}$ and >$125mgL^{-1}$, respectively. Therefore, BDE-47 is considered to be about over 80 times more harmful than BDE-209. In this study, the ecotoxic assessment based on population growth rate in S. costatum can be used as a baseline data for establishment of environment standard quality of BDE-47 and BDE-209 in the marine environment.

• Korean Journal of Remote Sensing
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• v.36 no.6_3
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• pp.1669-1679
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• 2020

This study examines the washing effect of precipitation on particulate matter (PM) and the rainwater quality (pH, electrical conductivity (EC), water-soluble ions concentration). Of six rain events in total, rainwater samples were continuously collected every 50 mL from the beginning of the precipitation using rainwater collecting devices at Pukyong National University, Busan, South Korea, from March 2020 to July 2020. The collected rainwater samples were analyzed for pH, EC, and water-soluble ions (cations: Na+, Mg2+, K+, Ca2+, NH4+, and anions: Cl-, NO3-, SO42-). The concentrations of particulate matter were continuously measured during precipitation events with a custom-built PM sensor node. For initial rainwater samples, the average pH and EC were approximately 4.3 and 81.9 μS/cm, and the major ionic components consisted of NO3- (5.4 mg/L), Ca2+ (4.2 mg/L), Cl- (4.1 mg/L). In all rainfall events, rainwater pH gradually increased with rainfall duration, whereas EC gradually decreased due to the washing effect. When the rainfall intensities were relatively weak (<5 mm/h), PM10 reduction efficiencies were less than 40%. When the rainfall intensities were enhanced to more than 7.5 mm/h, the reduction efficiencies reached more than 60%. For heavy rainfall events, the acidity and EC, as well as ions concentrations of initial rainwater samples, were higher than those in later samples. This appears to be related to the washing effect of precipitation on PM10 in the atmosphere.

• Ecology and Resilient Infrastructure
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• v.9 no.1
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• pp.1-14
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• 2022

The total maximum daily load (TMDL) implemented in Korea mainly manages the mainstream considering a single common pollutant and river discharge, and the river system is divided into unit watersheds. Changes in the water quality of managed rivers owing to the water quality management in tributaries and unit watersheds are not considered when implementing the TMDL. In addition, it is difficult to consider the difference in the load of pollutants generated in the tributary depending on the conditions of the water quality change in each unit watershed, even if the target water quality was maintained in the managed water system. Therefore, it is necessary to introduce the total maximum load management at tributaries to manage the pollution load of tributaries with a high degree of pollution. In this study, the HSPF model, a watershed runoff model, was applied to the target areas consisting of 53 sub-watersheds to analyze the effect of water quality changes the in tributaries on the mainstream. Sub-watersheds were selected from the three major areas of the Paldang water system, including the drainage basins of the downstream of the South Han-River, Gyeongan stream, and North Han-River. As a result, BOD ranged from 0.17 mg/L to 4.30 mg/L, and was generally high in tributaries and decreased in the downstream watershed. TP ranged from 0.02 mg/L - 0.22 mg/L, and the watersheds that had a large impact on urbanization and livestock industry were high, and the North Han-River basin was generally low. In addition, a pollution source reduction scenario was selected to analyze the change in water quality by the amount of pollution load discharged at each unit watershed. The reduction rate of BOD and TP according to the scenario changes was simulated higher in the watershed of the downstream of the North Han-River and downstream and midstream of the Gyeongan stream. It was found that the benefits of water quality reduction from each sub-watershed efforts to improve water quality are greatest in the middle and downstream of each main stream, and it is judged that it can be served as basic data for the management of total tributaries.

• KSBB Journal
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• v.24 no.5
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• pp.425-431
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• 2009

Hepatocyte growth factor (HGF) and its receptor play an important role in the formation and progression of glioma. In this study, I investigated the ability of HGF to recover of the PSA siRNA-suppressed cell proliferation, migration and invasion in U-251-MG cells. PSA siRNA-transfected U-251-MG cells showed the reduction of the proliferation, migration and invasion with compared to control. Treatment of HGF on the PSA siRNA-transfected U-251-MG cells recovered the ability of proliferation, migration and invasion. These data suggest that PSA and HGF may use unique and parallel signaling cascade leading to the proliferative, migrative and invasive phenotype of U-251-MG cells. I also showed that PSA cooperated with HGF to a migrative and invasive phenotype via the increased secretion of matrix metalloproteinase-2 (MMP-2) and MMP-9.

• Korean Journal of Animal Reproduction
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• v.18 no.1
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• pp.63-70
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• 1994

Thirty ewes received typical trauma to their oviducts and uterine horns from surgical embryo collection procedures. Ten percent Dexamethasone was used as an irrigant on the exposed abdominal tissue prior to closing the incision. The treatment group received 17mg colchicine Om! lewe) and the control group was administered a 1.0ml placebo(PSS). Fifteen ewes that were initially treated with 17mg /im colchicine showed acute colchicine toxicity within 2-5 days after initial treatment and were removed from the study. Due to acute colchicine toxicity at 17mg, the colchicine level was lowered to 8, 4 and 2mg(4 ewes/group). Treatments consisted of daily injections of colchicine. One ewe in the 8mg group developed toxicity on day 5. Therefore, ewes were then administered colchicine every other day from day 6 to day 14 postsurgeryat 4 and 2 mg. the second laparotomy was performed 9 weeks after first treatment. Following second laparotomy, the treatment group(n=5) received 4 mg colchicine every day for 14 days and there was no clinical symptoms of colchicine toxicity. The third laparotomy was performed by the same operators 5 weeks after final treatment and the adhesions scored. Adhesion grading was based on a scale of 0-4, with 4 being the most severe. The results of adhesion grading(> 3) at second laparotomy were not significantly different(P>0.05)between the two groups. Adhesion formation observed at third laparotomy showed a reduced, but not significant reduction (P>0.05) in the colchicine-treated ewes when compared with the controls. Ten ewes(5 control and 5 treatment)were examined cytogenetically by bone marrow analysis five days post-treatment. There was no difference(P>0.05)in the incidence of numerical or structural aberrations between the two groups.

• Journal of the Korea Institute of Building Construction
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• v.15 no.3
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• pp.281-289
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• 2015

Carbonation of concrete causes reduction of pH and subsequently causes steel corrosion for reinforced concrete structure. However, for plain concrete structure or PC product, it can lead to a decrease in porosity, high density, improvement of concrete, shrinkage-compensation. Recently, based on this theory, research of $CO_2$ curing effect has been performed, but it was mainly focused on its effects on compressive strength using only ordinary portland cement. Researches on $CO_2$ curing effect for concrete containing $CO_2$ reactive materials such as ${\gamma}-C_2S$, MgO haven't been investigated. Therefore, this study has performed experiments under water-binder ratio 40%, and the replacement ratios of ${\gamma}-C_2S$ and MgO were 90%. Micro-chemical analysis, measurement of compressive strength according to admixtures and $CO_2$ curing were investigated. Results from this study revealed that higher strength was measured in case of $CO_2$ curing compared with none $CO_2$ curing for plain specimen indicating difference between 1.08 and 1.26 times, in case of ${\gamma}-C_2S$ 90, MgO 90 specimen, incorporating high volume replaced as much as 90%, it was proven that when applying $CO_2$ curing, higher strength which has difference between 14.56 and 45.7 times, and between 6.5 and 10.37 times was measured for each specimen compared to none $CO_2$ curing. Through micro-chemical analysis, massive amount of $CaCO_3$, $MgCO_3$ and decrease of porosity were appeared.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.2
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• pp.527-534
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• 2019

Japanese sumac (Rhus javanica) is one of the common herbaceous plants growing over the country. This study was conducted to investigate the extraction characteristics and physiological activities inluding nitrite scavenging ability of the water extracts from leaf, fruit and bark of Japanease sumac. Extraction yield was 6.62~13.84%, free amino acids were detected as 24 kinds with 37.9 mg/100g in leaf extract, 23 kinds with 27.0 mg/100g in fruit extract and 27 kinds with 39.0 mg/100g in bark extract, respectively, and seven kinds essential amino acids were detected. Total contents of flavonoids equivalent to naringin were 587.2 mg/100g in bark extract, 557.3 mg/100g in fruit extract and 379.9 mg/100g in leaf extract, respectively. Total contents of phenolics equivalent to gallic acid were 111.2 mg/100g in leaf extract, 108.4 mg/100g in fruit extract and 80.4 mg/100g in bark extract, respectively. The nitrite scavenging ability of extracts was order of 61.93% in bark extract>57.38% in fruit extract>55.49% in leaf extract, and was 78.1~100% of those of BHT (butylated hydroxytoluene) equivalents at pH 1.2. The electron donating ability was order of 47.38% in fruit extract>43.06% in leaf extract>38.55% in bark extract, and was compared to 65.6%, 58.8% and 53.6% of those of BHT equivalents, respectively. The reduction power was evaluated to 37% higher in leaf extract, 43% higher in fruit extract and 46% higher in bark extract than those of BHT equivalents. The metal chelating ability of extracts was considerably low and was order of 27.3% in bark extract>20.6% in leaf extract>11.2% in fruit extract.

• Journal of Korean Society on Water Environment
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• v.27 no.1
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• pp.19-29
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• 2011

In order to assess the influences of bottom sediment on water quality, following measurement were made. (1) Estimations of pollutant loads from the bottom sediment based on mass balance concept, (2) measurements of pollutant concentrations in the sediment to assess the pollution level and influence potential, (3) in situ and laboratory measurements of Sediment Oxygen Demants (SOD) and pollutant load (sediment release) from bottom sediment. Analyses of inflow and outflow loadings using simple mass balance show that there are some variations found according to the pollutants. However, there is no consistent evidence that the sediment can be a source of pollutants. Pollutant concentrations in the sediment range 16~724.8 mg/kg (COD), 1.68 ~12.64 mg/kg (T-P), 5.6~76.8 mg/kg (T-N), 0.32~21.6 mg/kg ($NH_3$-N), 0.092~0.544 mg/kg ($NO_2$-N), 4.8~18.4 mg/kg ($NO_3$-N), and 1.59~11.23 mg/kg ($PO_4$-P). Measured SOD ranges $0.190{\sim}0.802g{\cdot}m^{-2}{\cdot}d^{-1}$ and measured release rate ranges $-1618.42{\sim}10mg/m^2{\cdot}d$(COD), $-12{\sim}16mg/m^2{\cdot}d$(T-P), $-197.37{\sim}140mg/m^2{\cdot}d$(T-N), $0.4{\sim}74.32mg/m^2{\cdot}d$($NH_3$-N), $-2.04{\sim}0.8mg/m^2{\cdot}d$ ($NO_2$-N), $-70{\sim}40mg/m^2{\cdot}d$ ($NO_3$-N), and $-26.11{\sim}28.55mg/m^2{\cdot}d$($PO_4$-P). All study results indicate that bottom sediments in the Seoha weir show only limited effects on the water quality. It implies that sediment dredging is not an effective option or management measure to reduce pollutant loading.