• Korean Journal of Organic Agriculture
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• v.6 no.1
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• pp.63-75
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• 1997

This study aims to find out the devices to minimize the amount of nitrate ingested from kimchi, the main way of vegetable intake for Koreans, and the basic data to deliver to calculate the total daily intake for Korean, investigating the year-round changes of nitrate content in vegetables for Kimche raw material, and changes of nitrate content by salting of chinese cabbage, and stewed kimchi through the use of different cooking methods. The results obtained were summarized as follow: over between 205-6655mg/kg f.w. in chinese cabbage, 480-3970mg/kg f.w. in chinese radish, 157-5820mg/kg f.w. in lettuce and 29-520mg/kg f.w. in cucumber respectively. Therefore it was strongly adviced to introduce the nitrate limit value of vegetables in Korea if the nitrate content in Kimchi should be reduced to meet the nitrate ADI(Acceptable Daily Intake, 219mg60kg b.w) of FAO.WHO, because the nitrate content in Kimchi reflects the nitrate content in vegetables. In order to keep the low nitrate content in Kimchi. it was adviced to remove the outer leaf which contains 2-3 times higher nitrate content compare to the inner leaf at the time of preparation, i.e. chinese cabbage, before the soaking treatment in salt solution for Kimchi making process. The dehydration by soaking treatment in salt solution occurred at 0.9%~4.7% in leaf midrib and more than 13%~24% in leaf blade. The nitrate content after soaking in salt solution was increased 107%~123% compared with before soaking, increasing rates of nitrate content in the outer and inner leaf midrib were higher than those in leaf blade. The increase of nitrate content in salt solution after soaking due to the dehydration of chinese cabbage by soaking treatment. The Kimchi stew(Kimchi JJige) was processed with and without animal oil, but the amount of nitrate in kimchi stew did not decrease both treatments, but it increased after the processing since the water in Kimchi stew has got low by boiling.

• Korean Journal of Organic Agriculture
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• v.19 no.spc
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• pp.238-241
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• 2011

An average Korean known to ingest 3.4 times of the nitrate ADI level are found to have taken in 97% of nitrates through vegetables. This study analyzed the contents of nitrates and chlorophyll in organic Chinese cabbages, a major favorite vegetable for Koreans, with a view to lowering daily intake of nitrate. Our findings show that, in organically cultivated cabbages, the further outward the leaf was located, the more significantly the contents of nitrates increased, with the midrib and leaf blade showing positive relationship of $r=0.789^{**}$, and $r=0.659^{**}$, respectively. In the case of the midrib, the contents increased as high as 79 times ranging from 40ppm for the innermost leaf to 3, 177ppm for the outermost one, and when it comes to the leaf blade, the contents rose as high as 87 times, showing a range of 40 ~ 3,481ppm. Our findings also suggest that it is advisable to discard 1/3 of the outermost leaves before eating Chinese cabbages, since the outer leaves with known high contents of chlorophyll also have high contents of nitrates.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.436-441
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• 2008

This work experimentally determined the effect of operating parameters such as temperature and solid retention time (SRT) on the phosphorus removal of municipal wastewater with waste-tire media. The experiments were carried out in pilot-scale moving bed biofilm reactor filled at a 0.15 filling ratio with the media. Total phosphorus (TP) removal efficiency was $91{\pm}5$, $75{\pm}16$, and $59{\pm}14%$ at the temperature of 9~10, 10~20, and $20{\sim}26^{\circ}C$, respectively. TP removal efficiency was $71{\pm}17$, $74{\pm}16$, $74{\pm}16$, and $68{\pm}18%$ at the SRT of 3.5~5, 5~10, 10~15, and 15~20 days, respectively. At the nitrate concentration of 1~3, 3~6, and 6~9 mg/L, TP removal efficiency was $82{\pm}9$, $68{\pm}18$, $47{\pm}7%$, respectively. The concentration of total phosphorus in the effluent was $0.1{\sim}1.8(0.8{\pm}0.4)mg/L$ regardless of operating conditions, which meets Korean phosphorus limit value, 2 mg/L, for discharge into receiving waters.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2358-2366
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• 2013

Iron oxide (ferrihydrite, hematite, and magnetite) coated silica gels were prepared using a low-cost, easily-scalable and straightforward method as the adsorbent material for arsenic removal application. Adsorption of the anionic form of arsenic oxyacids, arsenite ($AsO^{2-}$) and arsenate ($AsO{_4}^{3-}$), onto hematite coated silica gel was fitted against non-linear 3-parameter-model Sips isotherm and 2-parameter-model Langmuir and Freundlich isotherm. Adsorption kinetics of arsenic could be well described by pseudo-second-order kinetic model and value of adsorption energy derived from non-linear Dubinin-Radushkevich isotherm suggests chemical adsorption. Although arsenic adsorption process was not affected by the presence of sulfate, chloride, and nitrate anions, as expected, bicarbonate and silicate gave moderate negative effects while the presence of phosphate anions significantly inhibited adsorption process of both arsenite and arsenate. When the actual efficiency to remove arsenic was tested against 1 L of artificial arsenic-contaminated groundwater (0.6 mg/L) in the presence competing anions, the reasonable amount (20 g) of hematite coated silica gel could reduce arsenic concentration to below the WHO permissible safety limit of drinking water of $10{\mu}g/L$ without adjusting pH and temperature, which would be highly advantageous for practical field application.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.18 no.4
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• pp.293-302
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• 2008

Lead chromate is made by sodium dichromate and lead acetate, and has being used widely in the part of pigment, paints, inks, plastics and so on. Even though lead chromate has health hazards which like both lead and chromium, there are a few study about pigment workplaces using lead chromate in Korea. The purpose of this study is to evaluate workers' exposure levels and airborne lead and chromium concentration in the pigment workplaces using lead chromate. There are 20 workers in the total 5 workplaces. 10 workers(50%) have been exposed to lead and 3 workers(15%) have been exposed to chromium, which exceeded the American Conference of Governmental Industrial Hygienists(ACGIH) Threshold Limit Value (Pb: $0.05\;mg/m^3$, Cr: $0.012\;mg/m^3$) and Korean Ministry of Labor's Standard. Geometric mean (GM) of airborne lead was highest in pigment ($0.0421\;mg/m^3$), paint ($0.0020\;mg/m^3$) and PVC coloring ($0.0007\;mg/m^3$), respectively(p<0.05). The result of airborne chromium concentration was paint ($0.0033\;mg/m^3$), paint ($0.0004\;mg/m^3$) and PVC coloring ($0.0003\;mg/m^3$). Also the lead and chromium concentration in the manual process is each 30 times and 10 times higher than the value in automatic process(p<0.01). In the classified process by detail, the concentration of airborne lead was $0.0638\;mg/m^3$ in grinding & packaging, mixture & after-measuring ($0.0436\;mg/m^3$), filtration & drying ($0.0402\;mg/m^3$), lead nitrate & dissolution($0.0129\;mg/m^3$), pigment commitment & mixture ($0.0013\;mg/m^3$) and dispersion & grinding ($0.0010\;mg/m^3$) (p<0.05). Moreover the concentration of a sample in weighting & packaging was $0.0023\;mg/m^3$. The concentration of lead in workers' blood was pigment (15.12 ug/dl), paint (4.74 ug/dl) and PVC coloring (2.50 ug/dl), and some samples have exceeded biological exposure limit. In conclusion, the depending on their work industry and process, workers have been exposed to the high lead chromate.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.28 no.4
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• pp.475-488
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• 1995

In order to see the seasonal variation of nutrients and the limiting factors to the primary production in Deukryang Bay, both dissolved inorganic nutrients and salinity were measured in the surface waters during the periods from July 1992 to March 1993. The mean value of salinity was the lowest in ?all and the highest in early spring. Dissolved inorganic nitrogen (DIN) was the highest in winter and the lowest in summer. However, both phosphate and silicate were the highest in summer and the lowest in fall. Salinity was generally higher in the outer region than in the inner region of the bay.DIN content was nearly depleted (less than $2{\mu}M$) in summer. From fall to spring, DIN content was nearly depleted in the inner region and relatively high in the outer region of the Day. Phosphate was the highest in summer showing an opposite distribution pattern to salinity, and it was nearly depleted (less than $0.1{\mu}M$) in fall and winter. In spring, however, phosphate content was slightly high in the outer region. Silicate content showed an opposite distribution pattern to salinity in summer. in other seasons, However, the distribution pattern of silicate was similar to the salinity. DIN seemed to be a limiting factor for the primary production at all area of the bay in summer and at the inner region in other season. However, phosphate seemed to be a limiting factor at all area of the bay in fall and winter and at the inner region in spring. Silicate may limit the production of diatoms at the inner region of the bay in winter and spying. Both phosphate and silicate showed a good inverse relationship with salinity in summer, which indicates inputs of these nutrients from the freshwater runoff. In the other seasons, both nitrate and silicate showed a positive linear relationship with salinity in the outer region of the bay, suggesting that these two nutrients were mainly supplied by the inflow of the offshore costal water which had high nitrate content associated with vertical mixing.