• Corrosion Science and Technology
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• v.17 no.4
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• pp.176-182
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• 2018

Corrosion of the Cu alloy with 10wt% Ni in stagnant seawater with residual free chlorine was investigated. Despite that fact that Cu alloys are widely used for seawater applications due to their stubborn resistance to chloride attack, not much is known as to how the residual free chlorine in seawater affects corrosion of Cu and its alloys. In this work, immersion tests were conducted in the presence of different levels of chlorine for 90-10 Cu-Ni samples, one of the most frequently used Cu alloys for seawater application, mostly in shipbuilding. The results revealed no evidence for accelerated corrosion of the Cu-Ni alloy even in the presence of 5 ppm residual chlorine in seawater, signifying that the Cu-Ni alloy can be more tolerant to residual chlorine that has been commonly cited by the shipbuilding industry. However, comparison of polarization behavior of the alloy samples in the presence of different electrolytes with different concentrations of residual chlorine suggests that higher concentration of chlorine could increase the corrosion rate of the Cu-Ni alloy. Furthermore, it is suggested that microorganisms in the seawater could increase the corrosion rate of the Cu-Ni alloy by encouraging exfoliation of the corrosion product off the metal surface.

• Korean Journal of Veterinary Service
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• v.25 no.2
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• pp.141-151
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• 2002

In order to know the depletive changes of sulfadimethoxine and oxytetracycline residues in se겨m of dairy cattle intramusculally administered with sulfadimethoxine sodium(SDS) and oxytetracycline(OTC), the concentration of sulfadimethoxine and oxyteracycline was measured in serum of dairy cattle with using high performance liquid chromatography(HPLC). SDS and OTC was intramuscularlly administrated to dairy cattle at the rate of 10mg/kg(SDS) and 10mg/kg(OTC) body weight(recommended therapeutic dose) once to four dairy cattle. There were investigated the depletive changes of the sulfadimethoxine and oxytetracycline in serum of dairy cattle at the time 2, 4, 8 hours, 1st, 2nd, 3rd, 4th and 5th day after administration SMS and OTC, respectively. The results obtained were summarized as follows; 1. After intramuscularlly administration of the SMS, the mean concentrations of sulfamethazine in serum according to the time lapsed were showed 33.964 $\pm$ 4.435ppm at the 4 hours after withdrawal of medicated sulfadimethoxine sodium. And gradually according to the time lapsed, the concentrations of sulfadimethoxine residues in serum were significantly (p<.05) decreased 6.596 $\pm$ 3.402 ppm at 1st day, 0.217 $\pm$ 0.119 ppm at 3rd day and 0.057 $\pm$ 0.032 ppm at 4th day, respectively. 2. The mean residual concentration of OTC in serum according to the time lapsed after intramuscularly administration OTC were showed 0.743 $\pm$ 0.368ppm at the 8 hours. And gradually according to the time lapsed, the mean concentrations of OTC residues in serum of dairy cattle were significantly(p<.05) decreased such as 0.057 $\pm$ 0.047ppm at 3rd day and 0.039 $\pm$ 0.016ppm at the 5th day, respectively. In conclusion, this study could be suggested the relationship between administrated period, sulfonamides and tetracycline residual aspects in serum, and the importance of observing ceasing period of antibiotic drugs before forwarding livestocks to slaughter, Thus, this results would be able to be used the basic index for prevention of sulfonamides and tetracycline residues in dairy breedings.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.705-714
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• 2010

The residual oil concentrations in seawater and sediments were investigated along the Taean coast of Korea, following the Hebei Spirit oil spill, which occurred on 7 December 2007. The oil concentration in seawater ranged from 0.059 to $0.866\;{\mu}g/L$ for the tidal flat culture grounds and from 0.016 to $0.943\;{\mu}g/L$ in the fish cage areas in 2008. These were dominated by the seawater temperature relationship. Polycyclic aromatic hydrocarbons (PAHs) in sediments were also analyzed and the concentrations ranged from 3.4 to 509.7 ng/g dry weight. The average PAH level was higher in seawater from the Sinduri area than the Padori area, while the average PAH level in sediments was higher in Padori. The diagnostic ratio of PAHs was investigated to determine the origins of the PAHs. The PAHs in the Seongam area, which was not affected by the oil spill, are of pyrolytic origin, while the PAHs in Padori and Sinduri were of petrogenic origin. The residual oils in the areas affected by the oil spill tended to decrease over time, except in summer. The oils in pore water remained 6- to 16-fold higher, as compared to the seawater overlying the tidal flat, implying that residual oils will continue to influence the affected region for the foreseeable future.

• Environmental Engineering Research
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• v.25 no.4
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• pp.614-621
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• 2020

Antibiotic pollution is one of the factors contributing to the spread of antibiotic-resistant bacteria in the environment. Advanced oxidation and irradiation processes have been introduced to eliminate antibiotics from water and wastewater. However, few studies have reported the toxic effects of residual antibiotics and their byproducts induced by a treatment system. In this study, we compared the efficacies of chemical (high-performance liquid chromatography (HPLC)) and biological (antimicrobial susceptibility test) assays for measuring the concentrations of residual antibiotics after gamma irradiation for degrading amoxicillin, cephradine, lincomycin, and tetracycline. The concentrations of residual antibiotics estimated using the two assay methods were almost identical, except cephradine. In the case of cephradine, inhibited bacterial growth was observed that was equivalent to twice the concentration measured by HPLC in the samples subjected to gamma irradiation. The observed inhibition of bacterial growth suggested the generation of potentially toxic intermediates following antibiotic degradation. These results indicate that biological and chemical assays should be used in concert for monitoring antibiotic contamination and the toxic derivatives of antibiotic degradation. The results demonstrate that these four antibiotics can be decomposed by 2.0 kGy gamma-irradiation without toxic effects of their byproducts.

• Journal of Korean Society of Water and Wastewater
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• v.34 no.5
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• pp.311-321
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• 2020

In this study, a model to optimize residual chlorine concentrations in a water supply system was developed using a multi-objective genetic algorithm. Moreover, to quantify the effects of optimized residual chlorine concentration management and to consider customer service requirements, this study developed indices to quantify the spatial and temporal distributions of residual chlorine concentration. Based on the results, the most economical operational method to manage booster chlorination was derived, which would supply water that satisfies the service level required by consumers, as well as the cost-effectiveness and operation requirements relevant to the service providers. A simulation model was then created based on an actual water supply system (i.e., the Multi-regional Water Supply W in Korea). Simulated optimizations were successful, evidencing that it is possible to meet the residual chlorine concentration demanded by consumers at a low cost.

• Journal of Korean Society on Water Environment
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• v.30 no.3
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• pp.298-303
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• 2014

We measured by electrochemical method for TRC (total residual chlorine) in ocean. From the results of Au electrode used for working electrode through cyclic voltammetry test, we obtained charge in voltage ranged from 0.0V-1.0V, and analyzed correlations of charge for TRC. Reduction peak TRC was investigated to be approximately 0.65 V vs. Ag/AgCl, and in the case that salt concentrations and temperatures in ocean appeared different, charge was analyzed for being different in the same TRC. However, in the case that each condition was constant, charge was measured at highly correlations for TRC.

• Journal of Korean Society on Water Environment
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• v.40 no.1
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• pp.1-10
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• 2024

Algal blooms occur seasonally in the eutrophicated rivers or reservoirs, and some harmful cyanobacteria species produce toxic substances, which are directly or indirectly harmful to the ecosystem and terrestrial animals. So, the monitoring and control of harmful cyanobacteria occurrence and toxins residual in the aquasystem are important to preserve the water environment and secure public health. In this study, the four harmful cyanobacteria occurrences and toxic substance concentrations of two agricultural reservoirs in the southern part of Gyeonggi Province were investigated from August to October 2022. Among four harmful cyanobacteria (Microcystis sp., Anabaena sp., Oscillatoria sp., Aphanizomenon sp.), three kinds of cyanobacteria except Oscillatoria sp. were observed, and Microcystis sp. was the dominant cyanobacteria except for Anabaena sp. dominant result of a sample collected on October at reservoir B. The cell density of cyanobacteria was influenced by season and weather due to the length of daytime and concentrations of organic carbon and nitrogen. Three kinds of microcystin and anatoxin-a were quantitatively analyzed as total (in the cell body and water) and extracellular (in water) concentrations. The maximum total concentrations of anatoxin-a, microcystin-LR, microcystin-RR, and microcystin-YR were 0.1291 ㎍/L, 0.2776 ㎍/L, 0.3721 ㎍/L, and 0.0306 ㎍/L, respectively, in reservoir A and 0.3274 ㎍/L, 0.1495 ㎍/L, 0.2037 ㎍/L, and 0.0153 ㎍/L, respectively, in reservoir B.

• Journal of Soil and Groundwater Environment
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• v.10 no.3
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• pp.1-8
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• 2005

Fractional compositions and leaching potentials of Cd, Cu and Zn were investigated in the soils which had been disposed with the metal processing wastes, tungsten mine tailings and low quality coal mine area. Total concentrations of metals in these soils were higher than in non-polluted paddy and upland soils. Fractions of Cd, Cu and Zn were mostly reducible, organic and residual forms, but varied with origins of wastes. Residual fraction was a predominant form in the nonpolluted soils. Leaching potentials of metals were higher in polluted soils than in non-polluted soils. Metals leached were higher at pH 4.0 than 7.0 and increased with the duration time. After 25 to 35 hrs, metals released from soils reached a pseudoequilibrium. Leaching potential of metals in non-polluted soils was low due to high percentage of residual fractions.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.93-102
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• 2011

In this study, experiments on total digestion and sequential extraction were conducted in order to understand total metal contents, and mobility, bioavaliability and toxicity of metals in marine dredged sediment from Busan New Port. The total concentrations of arsenic and heavy metals in the dredged sediment were relatively low as follows: Al (2.36~2.96 wt.%), As (1.6~3.3 mg/kg), Ba (30.0~33.8 mg/kg), Cd (0.12~0.18 mg/kg), Cr (27.5~35.0 mg/kg), Cu (11.3~15.0 mg/kg), Fe (2.91~3.51 wt.%), Mn (324~408 mg/kg), Ni (18.8~23.8 mg/kg), Pb (23.8~31.3 mg/kg), and Zn (70.0~86.3 mg/kg). In addition, it was found that most of Al (87.5~95.9%), As (74.1~93.8%), Ba (71.8~77.6%), Cr (69.5~94.3%), Cu (50.0~78.7%), Fe (70.8~87.6%), Ni (64.5~75.3%), Pb (53.4~64.3%), and Zn (62.5~81.7%) existed in the residual fraction, meaning that those elements might come from natural sources. On the other hand, Cd and Mn were present mainly in the non-residual fraction. Due to low concentrations of toxic heavy metals and high percentage of residual fraction, it could be possible to reuse the dredged sediment for bricks, pavement base material, etc.

• Textile Coloration and Finishing
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• v.34 no.2
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• pp.93-101
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• 2022

In this study, the dyeing properties of supercritical fluid dyed cotton fabrics were investigated which use two types of dyes, such as C.I. Disperse orange and C.I. Disperse red 167. Dyeing temperature, pressure and leveling time were equally applied at 130 ℃, 250 bar, and 60 minutes with reference to the related literature, and experiments were performed at concentrations of 0.04, 0.1, 0.4 and 0.8 % o.w.f with different concentrations. Dyeability was confirmed through measurement of washing fastness and color coordinate, and a calibration curve of each dye was drawn up and the absorbance of the residual dye was measured to confirm the amount of residual dye and the dye exhaustion rate at the corresponding concentration. As a result of color difference measurement, as the concentration increased, the L^* value decreased and the K/S value increased. However, as the concentration increased, the increase in K/S value decreased compared to the input amount, and this tendency was more obvious in C.I. Disperse red 167 than in C.I. Disperse orange 155. The dye exhaustion rate which was calculated by using the amount of residual dye in the pot was also C.I. Disperse orange 155 was 96.16 % and C.I. Disperse red 167 was 94.57 %. However, as the dyeing concentration increased, the dye exhaustion rate decreased, that C.I. Disperse orange was 95.33 % and C.I. Disperse red 167 was 90.63 %. As a result of the washing fastness test for both dyes, dyed samples of which concentrations were 0.4 and 0.8 % o.w.f decreased by 0.5 ~ 1.0 grade. This is predicted because the dye did not completely adhere to the amorphous region of the cotton fiber and the dye simply adsorbed. The fastness to rubbing also maintained at least grade 3-4 up to the 0.1 % o.w.f concentration, but at the concentration of 0.4 % o.w.f or higher, it fell to grade 1 or lower, showing a very poor friction fastness.