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%.

New Application of Clay Filler for Carbon/Carbon Composites and Improvement of Filler Effect by Clay Size Reduction

Eui-Gyung Jeong,Jin-Hoon Kim,Young-Seak Lee 한국탄소학회 2010 Carbon Letters Vol.11 No.4

To investigate new potential application of a clay material for C/C composites, illite added C/C composites were prepared with various illite contents. The improvement of filler effect by illite size reduction was also investigated using wet ballmilling by evaluating illite/phenolic resin infiltration using bulk density and porosity measurements, chemical structural changes of the composites using XRD, and thermal oxidation stability in air of the composites using TGA. The size reduction of illite resulted in narrower particle size distribution and improved illite infiltration into carbon preform. And the resultant C/C composites prepared with illite had even more improved thermal oxidation stability in air, showing more increased IDTs up to 100℃, compared to those of the C/C composites with pristine illite, due to the SiC formation through carbothermal reduction between illite and carbon materials. The illite induced delay in oxidation of the illite-C/C composites was also observed and the delayed oxidation behavior was attributed to the layered structure of illite, which improved illite/phenol resin infiltration. Therefore, the potential use of illite as filler to improve oxidation stability of C/C composite can be promising. And the size reduction of illite can improve its effect on the desired properties of illite-C/C composites even more.

Effects of heat-treatment temperature on carbon-based composites with added illite

Eui-Gyung Jeong,Jin-Hoon Kim,Young-Seak Lee 한국탄소학회 2011 Carbon Letters Vol.12 No.2

To investigate new applications for illite as an additive for carbon-based composites, the composites were prepared with and without illite at different heat-treatment temperatures. The effects of the heat-treatment temperature on the chemical structure, microstructure, and thermal oxidation properties of the resulting composites were studied. As the heat-treatment temperature was increased, silicon carbide SiC formation via carbothermal reduction increased until all the added illite was consumed in the case of the samples heat-treated at 2,300℃. This is attributed to the intimate contact between the SiO2 in the illite and the phenol carbon precursor or the carbon fibers of the preform. Among composites prepared at all temperatures, those with illite addition exhibited fewer pores, voids, and interfacial cracks, resulting in larger bulk densities and lower porosities. A delay of oxidation was not observed in the illite-containing composites prepared at 2,300℃, suggesting that the illite itself absorbed energy for exfoliation or other physical changes. Therefore, if the illite-containing C/C composites can reach a density generally comparable to that of other C/C composites, illite may find application as a filler for C/C composites. However, in this study, the illite-containing C/C composites exhibited low density, even when prepared at a high heat-treatment temperature of 2300℃, although the thermal oxidation of the resulting composites was improved.

불소화 일라이트/폴리프로필렌 복합섬유 형성 및 열 및 기계적 특성

정의경 ( Eui Gyung Jeong ),이영석 ( Young Seak Lee ) 한국공업화학회 2011 공업화학 Vol.22 No.5

본 연구에서는 천연물을 이용한 기능성 섬유를 제조하기 위하여 미처리 및 불소화 일라이트를 첨가하여 일라이트/PP 복합섬유를 용융방사로 제조하고 그 물리적 특성을 고찰하였다. 복합필라멘트 형성 시 층상구조를 가지는 일라이트의 윤활특성으로 순수 PP 필라멘트에 비해 복합필라멘트의 직경이 감소하는 현상이 나타났으며, 불소화의 효과로 인한 계면 친화성 향상 및 분산성 향상으로 불소화 일라이트/PP 복합필라멘트의 직경이 순수 PP 필라멘트의 2/3 정도로 감소하였다. 미처리 및 불소화 일라이트 모두 일라이트/PP 복합필라멘트의 열안정성을 향상시키는 효과가 있는 것으로 확인되었다. 또한, 미처리 일라이트/PP 복합필라멘트는 연신 공정을 거칠 때 절사가 발생하여, 복합섬유로서 활용 될 수 없었으나, 불소화 일라이트/PP 복합필라멘트는 연신 후 순수 PP 필라멘트와 비슷한 인장강도를 가지고, 50%정도 증가한 탄성률을 가지는 것으로 보아 복합섬유로서 사용될 수 있음을 확인할 수 있었다. 일라이트/PP 복합필라 멘트를 형성 시, 불소화를 통하여 일라이트/PP간의 계면 친화성이 향상되고 고분자 내 분산성은 향상이 되었으나, 층간 결합력이 강한 비팽윤성 일라이트 고유의 성질로 인하여 일라이트의 박리나 PP의 일라이트 내 층간삽입이 충분히 발생하지 않은 것으로 보아 나노복합체가 아닌 마이크로 복합체를 형성하는 것으로 여겨진다. This study investigated illite/polypropylene (PP) composite filament formation via melt-spinning and evaluated their physical properties to prepare functional fibers using natural materials. When composite filaments were formed, the composite filaments exhibited smaller fiber diameters compared to that of neat PP filament because of the lubricant effect of illite induced by its layered structure. Moreover, fluorination effect increased interfacial affinity and dispersion in the polymer, resulting in smaller diameter of fluorinated illite/PP composite filament, which was 2/3 of the neat PP filament diameter. Addition of raw and fluorinated illite improved thermal stability of illite/PP composite filament. Raw illite/PP composite filament cannot be used for a practical application, because it broke during drawing process, whereas the fluorinated illite/PP composite filament can be used for a practical application, because it exhibited similar tensile strength of the neat PP filament and 50% increased modulus. Even with improved illite/PP interfacial affinity and illite dispersion in the polymer, illite/PP composite filament formed microcomposite, because non-expandable illite had strongly bound layers, resulting in only a little illite exfoliation and PP intercalation into illite.

Investigation of β-Lactamase-producing Multidrug-resistant Pseudomonas aeruginosa Isolated from Non-Tertiary Care Hospitals in Korea

( Eui Suk Sohn ),( Jeong Sik Yoo ),( Jeom Kyu Lee ),( Kyeong Min Lee ),( Gyung Tae Chung ),( Eun Shim Shin ),( Sun Young Han ),( Sang Hee Lee ),( Joon Kim ),( Yeong Seon Lee ) 한국미생물생명공학회 2007 Journal of microbiology and biotechnology Vol.17 No.10

Preparation and Characterization of Electrospun TiO<SUB>2</SUB>-Activated Carbon Complex Fiber as Photocatalyst

Min-Jung Jung,Eui-Gyung Jeong,Jeen-Seok Jang,Young-Seak Lee 한국탄소학회 2010 Carbon Letters Vol.11 No.1

In this study, TiO2-Activated carbon (AC) complex fibers were prepared by electrospinning for the synergetic effect of adsorption and degradation of organic pollutant. The average diameter of these fibers increased with increasing the amount of AC added, except for 1AC-TOF (AC/TiO2 =1/40 mass ratio). After calcinations at 500℃, long as-spun fibers were broken and their average diameter was slightly decreased. The resultant fibers after calcination had rough surface and sphere shapes like a peanut. From XRD results, it was confirmed that as-spun fibers were changed to anatase TiO2 fiber after calcinations at 500℃. The prepared TiO2-AC complex fibers could remove procian blue dyes by solar light irradiation with high removal property of 94~99%. The PB dye was rapidly removed by adsorption during the initial 5 minutes. But after 5 minutes, dye removal was occurred by photodegradation. In this study, the most efficient AC/TiO2 ratio of TiO2-AC complex fibers was 5/40, showing the synergetic effect of adsorption and photodegradation. It is expected that the TiO2-AC complex fibers can be used to remove of organic pollutants in water system.

Application and evaluation of boron nitride-assisted liquid silicon infiltration for preparing Cf/SiC composites

Jin-Hoon Kim,Eui-Gyung Jeong,Se-Young Kim,Young-Seak Lee 한국탄소학회 2011 Carbon Letters Vol.12 No.2

C/SiC composites were prepared by boron nitride (BN)-assisted liquid silicon infiltration (LSI), and their anti-oxidation and mechanical properties were investigated. The microstructures, bulk densities, and porosities of the C/SiC composites demonstrated that the infiltration of liquid silicon into the composites improved them, because the layered-structure BN worked as a lubricant. Increasing the amount of BN improved the anti-oxidation of the prepared C/SiC composites. This synergistic effect was induced by the assistance of BN in the LSI. More thermally stable SiC was formed in the composite, and fewer pores were formed in the composite, which reduced inward oxygen diffusion. The mechanical strength of the composite increased up to the addition of 3% BN and decreased thereafter due to increased brittleness from the presence of more SiC in the composite. Based on the anti-oxidation and mechanical properties of the prepared composites, we concluded that improved anti-oxidation of C/SiC composites can be achieved through BN-assisted LSI, although there may be some degradation of the mechanical properties. The desired anti-oxidation and mechanical properties of the composite can be achieved by optimizing the BN-assisted LSI conditions.

과전압 보호용 황동전극 기체방전관의 절연파괴 특성

김민일 ( Min Il Kim ),정의경 ( Eui Gyung Jeong ),이세현 ( Sei Hyun Lee ),이영석 ( Young Seak Lee ) 한국공업화학회 2010 공업화학 Vol.21 No.2

공업화학(전기화학, 분석화학 포함) 촉매/반응공학 혼성반도체로 제조된 염료감응형 태양전지의 전기화학적 특성

이성규 ( Sung Kyu Lee ),정의경 ( Eui Gyung Jeong ),임지선 ( Ji Sun Im ),이영석 ( Young Seak Lee ) 한국화학공학회 2011 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.49 No.2

In this study, the TiO2/V2O5 hybrid semiconductors were prepared by mixing TiO2 and V2O5, and a subsequent smash process to reduce the recombination of electron and improve the efficiency of solar cells. Dye-sensitized solar cells were constructed using the resultant hybrid semiconductor, and their electrochemical properties were also investigated. The photocurrent-voltage curve obtained with the cells indicated a significant increase in the efficiency from 2.9 to 5.7% by the factor of 2 compared to the result obtained only with TiO2. It is believed that the introduction of V2O5 effectively transport electrons in the TiO2 conduction band to FTO glass and suppress recombination with the dye and/or the electrolyte, thus yielding an efficient performance of the dye sensitized solar cell. The impedance values also indicated a decrease of resistance in the interface of TiO2/dye/electrolyte supporting the constructive contributions of the smashed TiO2/V2O5 hybrid semiconductors for the efficiency.

Effect of Exopolymers of Aureobasidium pullulans on Improving Osteoporosis Induced in Ovariectomized Mice

( He Bok Song ),( Dong Chan Park ),( Gyung Min Do ),( Seung Lark Hwang ),( Won Kyu Lee ),( Heun Soo Kang ),( Bok Ryun Park ),( Hee Jeong Jang ),( Chang Woo Son ),( Eui Kyun Park ),( Shin Yoon Kim ),( 한국미생물생명공학회 2006 Journal of microbiology and biotechnology Vol.16 No.1