본 연구는 농약 허용물질목록관리제도(PLS) 도입이 농산물 중 잔류농약 부적합에 어떠한 영향을 미쳤는지 확인 하기 위해 2018년부터 2020년까지 서울 강서지역에서 유통되는 농산물을 대상으로 잔류농약을 검사하였다. 농산물 8,081건을 대상으로 340종의 동시분석 농약에 대해 GCMS/ MS, GC-MSD, HPLC-MS/MS를 이용하여 분석하였고, 부적합 농산물은 2018년 67건(2.5%), 2019년 49건(1.9%), 2020년 39건(1.4%)으로 나타났다. PLS제도 도입 전과 도입 후의 잔류농약 부적합 증감효과를 알아보기 위해 카이 제곱 검정을 통한 교차분석 결과에서 χ2=8.383, P=0.015 (95% 신뢰수준)를 나타내어 PLS 제도 도입 후에 부적합률이 유의하게 감소함을 알 수 있었다.

A method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for neonicotinoid pesticide analysis in agricultural products. Four compounds (imidacloprid, clothianidin, acetamiprid, thiacloprid) were extracted with acetonitrile from agricultural products and cleaned up by NH2 solid-phase extraction procedure, and eluted with 0.1% formic acid in methanol/dichloromethane (5/95, v/v). The limit of detection and quantification were 0.0001-0.0005 mg/kg and 0.001 mg/kg, respectively. The mean recoveries of neonicotinoid pesticide from agricultural products were in the range of 90.7-100.9% and 94.4-99.8%, as spiked at 0.2 mg/kg and 0.02 mg/kg, respectively. This validation satisfied the national criteria for pesticide analytical methods. In summary, The present method is fast, precise and sensitive enough for the Positive List System (PLS), and we conclude that the method is also suitable for neonicotinoid pesticide determination in a wide range of agricultural products.

A sintering process for copper based films using a rapid thermal process with infrared lamps is proposed to improve the electrical properties. Compared with films produced by conventional thermal sintering, the microstructure of the copper based films contained fewer internal and interfacial pores and larger grains after the rapid thermal process. This high-density microstructure is due to the high heating rate, which causes the abrupt decomposition of the organic shell at higher temperatures than is the case for the low heating rate; the high heating rate also induces densification of the copper based films. In order to confirm the effect of the rapid thermal process on copper nanoink, copper based films were prepared under varying of conditions such as the sintering temperature, time, and heating rate. As a result, the resistivity of the copper based films showed no significant changes at high temperature (300 oC) according to the sintering conditions. On the other hand, at low temperatures, the resistivity of the copper based films depended on the heating rate of the rapid thermal process.

The effective use of disinfection and sterilization is important in preventing healthcare associated infections. Especially, multi-drug resistant organism and spore-forming bacteria are serious pathogens. Therefore, control of a nosocomial infection is emerging as a big problem. It is efficiently necessary to eliminate the pathogen. In this study, the components of sterilant were optimized. The optimized sterilant was applied for efficiency of sterilization using G. stearothermophilus E. coli, S. aureus as a standard microorganism. Our results were shown as follows : The decomposition or loss of potency of sterilant in small containers did not appeared for one month at ambient temperature. All of hydrogen peroxide 0.5%, peracetic acid 0.01%, and IPA 60% was effective for sterilization of E. coli, S. aureus using dilution method. Two kinds of sterilants(hydrogen peroxide 2%+peracetic acid 0.1%+IPA 0.5%, hydrogen peroxide 4%+peracetic acid 0.06%+IPA 1%) were bacteriocidal(> 6 log reduction). Microorganisms(E. coli, S. aureus) which treated with these sterilants for 2min were not grown in LB broth at 7 days culture. The gas plasma system for sterilization was applied. The sterilant solution(hydrogen peroxide 20%+IPA 5%) was vaporized in the sterilization chamber. The vaporized sterilant was bacteriocidal and sporocidal(> 6 log reduction) using G. stearothermophilus E. coli, S. aureus as biological indicators

In the present work, physicochemical treatments were introduced for de-aggregation and stable dispersion of detonation nanodiamonds (DND) in polar solvents. The DNDs in water exhibited a particle size of 138 nm and high dispersion stability without particular treatment. However, the DNDs in ethanol were severely aggregated to several micrometers in size and showed poor dispersion stability with time. To break down aggregates of DNDs and enhance the dispersion stability of them in ethanol, mechanical force and chemical surfactant were introduced as functions of zirconia ball size, kind of surfactant and amount of surfactant added. From the analyses of average particle size and Turbiscan results, it was suggested that the size of DNDs in ethanol can be reduced by only mechanical force; however, the DNDs were re-aggregated due to high surface activity. The long-term dispersion stability can be achieved by applying mechanical force to break down the aggregates of DNDs and by preventing re-aggregation of them using proper surfactant.

Multi-source evaporation is one of the methods to improve the thickness uniformity of thin films deposited by evaporation. In this study, a simulator for the relative thickness profile of a thin film deposited by a multi-source evaporation system was developed. Using this simulator, the relative thickness profiles of the evaporated thin films were simulated under various conditions, such as the number and arrangements of sources and source-to-substrate distance. The optimum conditions, in which the thickness uniformity is minimized, and the corresponding efficiency, were obtained. The substrate was a 5th generation substrate (dimensions of 1300 mm × 1100 mm). The number of sources and source-to-substrate distance were varied from 1 to 6 and 0 to the length of the major axis of the substrate (1300 mm), respectively. When the source plane, the area on which sources can be located, is limited to the substrate dimension, the minimum thickness uniformity, obtained when the number of sources is 6, was 3.3%; the corresponding efficiency was 16.6%. When the dimension of the source plane is enlarged two times, the thickness uniformity is remarkably improved while the efficiency is decreased. The minimum thickness uniformity, obtained when the number of sources is 6, was 0.5%; the corresponding efficiency was decreased to 9.1%. The expansion of the source plane brings about not only the improvement of the thickness uniformity, but also a decrement of the efficiency and an enlargement of equipment.

In the present work, bismuth nanopowders with various particle size distributions were synthesized by controlling argon (Ar) gas flow rate and chamber pressure of a gas condensation (GC) apparatus. From the analyses of transmission electron microscopy (TEM) images and nitrogen gas adsorption results, it was found that as Ar gas flow rate increased, the specific surface area of bismuth increased and the average particles size decreased. On the other hand, as the chamber pressure increased, the specific surface area of bismuth decreased and the average particles size increased. The optimum gas flow rate and chamber pressure for the maximized electrochemical active surface area were determined to be 8 L/min and 50 torr, respectively. The bismuth nanopowders synthesized at the above condition exhibit 13.47 of specific surface area and 45.6 nm of average particles diameter.

In the present work, ethylene glycol-based (EG) copper oxide nanofluids were synthesized by pulsed wire evaporation method. In order to explode the pure copper wire, high voltage of 23 kV was applied to the both ends of wire and argon/oxygen gas mixture was used as reactant gas. EG-based copper oxide nanofluids with different volume fraction were prepared by controlling explosion number of copper wire. From the transmission electron microscope (TEM) image, it was found that the copper oxide nanoparticles exhibited an average diameter about 100 nm with the oxide layer of 2~3 nm. The synthesized copper oxide consists of CuO/ phases and the Brunauer Emmett Teller (BET) surface area was estimated to be . From the analyses of thermal properties, it is suggested that viscosity and thermal conductivity of EG-based copper oxide nanofluids do not show temperature-dependent behavior over the range of 20 to . On the other hand, the viscosity and thermal conductivity of EG-based copper oxide nanofluids increase with volume fraction due to the active Brownian motion of the nanoparticles, i.e., nanoconvection.

Ethylene glycol-based Cu nanofluids were prepared by pulsed wire evaporation (PWE) method. The structural properties of Cu nanoparticles were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The average diameter and Brunauer Emmett Teller (BET) surface area of Cu nanoparticles were about 100 nm and , respectively. The thermal conductivity and viscosity of copper nanofluid were measured as functions of Cu concentration and temperature. As the volume fraction of Cu nanoparticles increased, both the enhanced ratios of thermal conductivity and viscosity of Cu nanofluids increased. As the temperature increased, the enhanced ratio of thermal conductivity increased, but that ratio of viscosity decreased.

The silver nanofluids were synthesized by the pulsed wire evaporation (PWE) method in a liquid-gas mixture. The size and microstructure of nanoparticles in the deionized water were investigated by a particle size analyzer (PSA), transmission electron microscope (TEM), and scanning electron microscope (SEM). Also, the synthesized nanofluids were investigated in order to assess the stability of dispersion of nanofluid by the zetapotential analyzer and dispersion stability analyzer. The results showed that the spherical silver nanoparticle formed in the deionized water and mean particle size was about 50 nm. Also, when explosion times were in the range of 20~200 times, the absolute value of zeta potential was less than -27 mV and the dispersion stability characteristic of low concentration silver nanofluid was better than the high concentration silver nanofluid by turbiscan.

In this paper, the electrochemical non-enzyme immunosensor has been developed for the determination of salmonella antigen, using inverse voltammetry. For the estimation of salmonella antigen concentration, the nanoparticles synthesized by microemulsion method were conjugated with salmonella antigen. Then, the immunocomplex between antibody immobilized on the transducer surface and antigen containing a magnetic nanoparticles was formed. From the linear relationship between the reduction peak current of Fe(III) and salmonella antigen concentration, it is suggested that the electrochemical non-enzyme biosensor is applicable to detect salmonella antigen in the concentration range of