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고상추출카트리지를 이용한 잔류농약 다중분석과정에서 정제용매에 따른 회수율 비교
두옥주,정보경,김경식,정의근,김진곤,김명희 한국환경농학회 2002 한국환경농학회지 Vol.21 No.2
채소류 중 비교적 matrix효과가 적고, 수분 함량이 적절하여 회수율이 양호한 오이를 대상으로 하여 총 16종의 농약 성분을 A, B 두 group으로 나누어, 농약의 동시 다성분 분석의 전처리 과정 중 정제에 사용하는 용출용매로서 5%~20%의 acetone/hexane과 5%~20%의 ethyl acetate/hexane을 사용하여 각각의 회수율을 분석하여 얻은 결과는 다음과 같다. Acetone/hexane을 사용한 경우 5% acetone에서 총 16종의 농약 성분 중 ethalfluralin, trifluralin, chlorothalonil 등 11종의 농약은 높은 회수율을 보였으나, alachlor와 iprodione, endosulfan sulfate, bifenthrin, fenarimol은 매우 낮은 회수율을 나타내었고, 10% 이상의 acetone/hexane에서는 bifenthrin과 fenarimol 제외한 14종의 농약에서 높은 회수율을 얻을수 있었다. 그러나 bifenthrin은 20%의 acetone/hexane을 사용한 경우는 용출되지 않았고, fenarimol은 10% 이하의 acetone/hexane을 사용하였을 때는 낮은 회수율을 나타냈었다. Ethyl acetone/hexane을 사용하여 총 16 종의 농약 성분의 회수율 분석을 한 결과, 5% ethyl acetone에서 ethalfluralin, α-endosulfan, β-endosulfan (A group), vinclozolin, tetradifon, cyprethrin, fenvalerate (B group)에서만 70% 이상의 회수율을 얻었다. 10%의ethyl acetone/hexane을 사용하여 분석한 경우는 trifuralin, chlorothalonil, α-endosulfan, β-endosulfan, endosulfan sulfate(A group), vinclozolin, procymidone, tetradifon, cypermethrin, 그리고 fenvalerate(B group) 에서는 70% 이상의 회수율을 얻었고, 20%의 cthyl acetone/hexane 을 사용하여 분석한 경우는 5%나 10%의 ethyl acetone/hexan 을 사용하여 분석했을 때보다 좋은 결과를 나타내어 전체 16종의 농약 중 14종에서 75% 이상의 회수율을 얻었으나, alachlor와 bifenthrin은 매우 낮은 회수율을 보여서 ethyl acetate 와 hexane의 혼합용매가 이들 두 농약성분의 분석에는 적합하지 않은 용출 용매임을 알 수 있었다. A study was carried out to optimize the cleanup step using a solid-phase extraction (SPE) cartridge, SupelClean^(TM) Florisil, for multiresidue analysis of 16 pesticides in cucumber matrix. Eluting efficiencies of two solvent systems including acetone/n-hexane and ethyl acetate/n-hexane mixtures were critically evaluated by recoveries of target anaytes from the SPE Florisil column. Based on the recovery as a measure of eluting efficiency, an acetone/n-hexane (20/80,v/v) mixture provided more than 80% recovery for 15 pesticides except bifenthrin. In case of ethyl acetate/n-hexane, 14 pesticides showed recoveries higher than 75%, while those for alachior and bifenthrin were less than 30%.
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유상근,정윤진,허관용,정의근 대한상하수도학회 1997 상하수도학회지 Vol.11 No.2
The purpose of this study is to get optimum operating factors of Upflow Anaerobic Sludge Blanket (UASB) reactor by introducing methods that make it to reduce inhibition possible in each process wastewater treatment. The used substrates, concentrated corn starch liquid (CSL) wastewater, modified starch, filtering and decoloring wastewater, ion refining wastewater, and mixed wastewater including modified starch and not including modified starch, are generated from molasses process. The seeding sludge is the digested sludge that had been applied to molasses wastewater. Batch test to reduce the inhibition factors that might be existed in each wastewater was examined. Based on the this test, the optimum operating factors according to alkalinity and pH variation was studied through the continuous test using three 5.5 L UASB reactor. The first reactor added NaHCO_3 to control alkalinity. The hydraulic retention time (HRT) reduced to 8 hours and the organic loading rate increased gradually. The second reactor changed the pH of influent from 7.0 to 6.0 using NaOH. The third reactor was operated without changes to compare the above two reactors. As the result, the inhibition in concentrated CSL wastewater was removed by adding iron (II). When trace metals were added to mixed wastewater not including modified starch, the digestability by gas production rate increased to more fifty percentage than mixed wastewater that was not adding the trace metals. The reason that the inhibition did not decreased in spite of adding trace metals and nutrients was influenced by high concentration generated during the acid fermentation. The UASB reactors using the mixed wastewater with the most effective performance were operated as 500 mg/L as CaCO_3 alkalinity and 6.0 pH at steady state, and at this time, the gas production rates were 283 and 311mL gas/g COD_added. The COD removal rates were 84.7 and 86.3%, respectively.
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알루미늄 고진공 다이캐스팅 공법을 적용한 전륜 서브프레임 개발
윤석진(Sukjin Yoon),김성구(Seonggoo Kim),김규록(Gyurok Kim),정의근(Euikeun Jeong),이용욱(Yonguk Lee),조영건(Younggun Cho) 한국자동차공학회 2020 한국자동차공학회 학술대회 및 전시회 Vol.2020 No.11
In the automobile industry, many parts are manufactured by applying aluminum materials to improve fuel efficiency and reduce vehicle weight. In particular, in order to design and manufacture future electric vehicles, the weight reduction of vehicles is receiving more and more challenges. In the case of a suspension part, since it is located in the lower part of the vehicle, it has a great advantage of improving fuel economy due to weight reduction. This paper describes the development stage of a front wheel subframe with a welded structure of aluminum high vacuum die casting method and extrusion method. The result of the aluminum subframe study showed that the weight was reduced by 5.6㎏ and natural frequency was improved by 16㎐ compared with the steel subframe.
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황영숙(Yuong-Sook Hwang),김양숙(Yang-Suk Kim),이성득(Sung-Deuk Lee),백수현(Soo-Hyun Baek),김경식(Gyung-Sig Kim),두옥주(Ok-Ju Tu),정보경(Bo-Kyung Jung),조진호(Jin-Ho Cho),정애희(Ae-Hee Chung),정의근(Eui-Geun Jung),장미라(Mi-Ra Jang),윤 환경독성보건학회 2003 환경독성보건학회지 Vol.18 No.4
This study was carried out to investigate the 106 kinds of pesticide residues in agricultural products (n =3,614) by GC, for the northern area of Seoul from March (1999) to December (2000). The detection rate of pesticide residues in samples was 5.0% (mean: 2.86±7.22 mg/kg, n=180). The order of the agricultural products in which pesticide residues were detected was korean lettuce> perilla leaf, pepper> chinese cabbage> leek> spinach. The percentage of the agricultural products in excess of MRL was 2.0% (n=73). The agricultural products in excess of MRL were korean lettuce(n=15), perilla leaf(n=13), leek (n=6), spinach(n=6), pepper (n=5). chwinamul (n=5), etc. The order of the pesticide residues which were detected in agricultural products was procymidone, endosulfan, chlorpyrifos, vinclozolin, chlorothalonil and diazinon. The average residual values of procymidone, endosulfan, chlorpyrifos, vinclozolin, chlorothalonil and diazinon were 4.07, 1.24, 1.27, 2.83, 17.71 and 1.48 respectively. The pesticide residues in excess of MRL were chlorpyrifos (n=19), endosulfan (n=12), procymidone (n=9), vinclozolin (n=6), etc, and the measured concentration ranges of chlorpyrifos, endosulfan, procymidone, vinclozolin, pyrazophos, diazinon and EPN were 0.03-6.72, 0.18-5.8, 2.0-60.8, 1.70-20.33, 0.26-1.21, 0.59-4.3 and 0.28-4.19 respectively.
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