• Journal of Environmental Science International
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• v.5 no.5
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• pp.561-567
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• 1996

A method for the simultaneous analysis of 31 residual organic chloride pesticides was studied using gas chromatography. Prepared analytical samples were injected to gas chromatography (HP 5890 Series II plus) on the Ultra-2 column with ECD. The packing materials for column were changed as the following reagents ; florisil and alumina N, The residual solution was loaded to column and was elected pith erection solvents ; ether : benzene (2 : 8) solution, hexane : benzene (1 : 1) solution, dichloromethane, acetone, and methanol. The analytical results showed that 6 kinds of organic chlorides were not detected when florisil (first condition) was used as the column packing material. The nondetected 6 kinds of organic chlorides in the first analytical condition were detected and the recoveries of thrin-pesticides were increased, in particular, captan and captafol, but the recoveries of benzene hexachloride compounds were decreased when dichloromethane and methanol were added as elution solvents (pac'king material was florisil as in the first condition). The recoveries of dichlornuanid, chlorofenvinfos, folpet, and dicofol were increased and that of aldrin was increased, but those of captan and captafol were not good when alumina N was used as the packing material. To detect simultaneously thrin-pesticides, captan, and captafol, florisil and alumina N were used as the packing materials. The elution result showed that captan and captafol were not detected. This was because the column was activated insufficiently. The analytical method was the best (31 kinds of organic chlorides in the residual pesticides were detected sharply and showed high sensitivity) when the column (packing materials were florisil and alumina N: together) was fuliy activated and the impurities were removed using various elution solvents.

• Journal of the Korean earth science society
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• v.26 no.7
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• pp.668-673
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• 2005

To collect or transfer samples of gaseous pollutants, various types of tubing are used. Hence, to analyze the uncertainties associated with the use of tubings, a series of comparative test were designed and conducted using the RSC standards with different concentration ranges. For the purpose of this study, we prepared tubings made of six different types of material which include: [1] silco-steel (S1), [2] stainless steel (S2), [3] silicone (S3), [4] PTFE Teflon (T1), [5] tygon (T2), and [6] brass (B). The patterns of RSC loss on to tubing walls, when compared on the basis of the least reactive material S1, exhibited that the extent of RSC loss varied dynamically. It was found that Teflon is highly stable. However, other materials tend to exhibit contrasting patterns of loss. S2 and B show significant loss of light RSC $(H_2S\;and\;CH_3SH)$, while S3 and T2 experience notable loss of heavy RSC (DMS and DMDS).

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.361-368
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• 2004

We separated the multilayer structure of CD-R(compact disk-recordable) and investigated optimal spot marking conditions and physical and chemical transitions in response to various laser beam energh levels. Spot marking(80 ${\mu}{\textrm}{m}$ spot size) was produced on the surface of each layer using a Q-switched Nd:YAG laser between 27 mJ and 373mJ. By investigating resulting pit formation with Optical Microscopy(OM) and Optical Coherence Tomography(OCT), we analyzed the formation process of spot marking in the multilayer structure of different chemical composition. The localized heating of the substrate in the multilayer thin film caused the short temporal thermal expansion, and absorbed optical energy between reflective and dye interfaces melted dye and increased the volume. During the cooling phase, formation of pit and surrounding rim can be explained by three distinct processes; effect of surface tension, evaporation by spontaneous temperature increase due to laser energy, and mass flow from the recoil pressure. Our results shows that the spot marking formation process in the multilayer thin film is closely related to the layers' physical, chemical, and optical properties, such as surface tension, melt viscosity, layer thickness, and chemical composition.

• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2000.11a
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• pp.41-41
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• 2000

부유부상 공정은 현재 신문고지와 사무용 고지의 탈묵을 통한 신문용지 및 화장지 제조 에 널리 사용되고 있는 고지재활용을 위한 핵심공정이다. 하지만 이들 공정은 갈수록 열악 해지는 국내 고지원료의 품질변화에 따라서 잉크 및 토너의 분리효율이 저하되고 있어 생산 되는 탈묵 펄프의 품질저하, 리젝트 발생량의 증대, 폐수 처리공정의 부하 증가 등 다양한 문제점을 발생시키고 있어 이에 대한 대책의 수립이 시급히 요청되고 있다. 현재와 같이 다양한 형태의 잉크 및 인쇄방식으로 인쇄된 많은 종류의 재활용지가 원료 로 투입되고 있는 경우 탈묵공정의 효율 향상을 위해서는 부유부상 공정에 대한 좀 더 체계 적이고 논리적인 접근이 필요하다. 이러한 문제점을 극복하기 위해 먼저 고지 재활용 공정 의 핵심 단위공정인 부유부상 공정에 관련된 복잡한 문제점을 단순화하여 고상 및 액상의 표면화학적 특성을 평가하고, 이에 따른 부유부상 공정의 효율을 분석하였다. 본 연구에서는 부유부상 공정을 기초과학적 측면에서 구명하기 위해 마이크로 크리스탈린 셀룰로오스(Microcrystalline cellulose: MCC)를 모델 물질로 사용하였고, 친수성 의 표면 특 성을 나타내는 MCC의 표면 특성을 바꾸기 위하여 AKD(alkyl ketene dimer)로 처리비율을 달리하여 사이징 처리하였다. 부유부상 실험에 사용된 MCC는 친수성을 띠는 것과 소수성 을 부여한 것을 구별하고 그 비율을 백색도를 통해 측정하기 위하여 자체적으로 친수성을 가지는 MCC는 세척 견뢰도가 높은 검은색 염료로 염색하였다. 준비된 친수성과 소수성 M MCC의 혼합비율 별로 패드를 작성하여 백색도를 측정함으로써 검량선을 작성하였다. 또한 부유부상 시간에 따른 제거효율을 알아보기 위하여 부유부상 시간별로 각각의 리젝트율과 수율올 측정하고, 리젝트 시료로부터 패드를 제조하여 백색도를 측정하였다. 실험 결과 소수성 MCC의 소수화 정도에 따라서 리젝트율이 증가하였으며, 이를 통해 표 면에 소수성을 띠는 입자는 소수성이 강할수록 부유부상공정에서 제거율이 증가한다는 것을 확인하였다. 부유부상 처리한 MCC로 패드를 제조한 뒤 백색도를 비교한 결과에서도 이를 확인하였다. 한편 리젝트로 함께 제거된 MCC 내에 존재하는 친수성 MCC의 양은 극히 미 세하였다. 또한 부유부상를 실시하는 초기에 상당량의 리젝트가 발생함을 확인하였는데, 이 는 전체 부유부상을 통해 제거되는 양의 45-68%였다. 한편 부유부상이 진행됨에 따라서 리젝트 양의 증가폭이 둔화되는 경향을 나타내었다. 이러한 경향은 MCC의 소수성이 강할 수록 더욱 뚜렷하게 나타났다. 이를 통해 계 내로부터 소수성인 물질이 급속하게 제거됨을 알 수 있었으며 필요 이상의 부유부상 처리는 잉크제거 효율을 높일 수는 있으나 소모되는 시간에 비하여 비효과적임을 알 수 있었다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.169-175
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• 1992

The Maximum Dry Density (${\gamma}_{dmax}$) and the Optimum Moisture Content (${\omega}_{opt}$) of the soil samples are determined from the compaction curve plotted with the laboratory compaction test results. But in this study three reported tests, and tests on the silty clay and the sandy silt samples are reviewed through the interpolation methods using an equation of the Moisture-Density relations induced from Lagrange's Interpolation Formula without drawing the compaction curves. As the results of the study ${\gamma}_{dmax}$ and ${\omega}_{opt}$, were calculated rapidly and simply using the equation and approached to the results from the compaction curves, and also due to the differences of the ${\gamma}_{dmax}$ and ${\omega}_{opt}$, calculated from the equation between the compaction curves were within $0.01g/cm^3$(0.5%) and 0.4% respectively the method in this study be recommended as a simple method determining ${\gamma}_{dmax}$ and ${\omega}_{opt}$, during the laboratory compaction tests.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.7 no.3
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• pp.175-182
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• 2009

The spent cationic exchange resins and anionic exchange resins were separated from mixed spent exchange resins by a fluidized bed gravimetric separator. The separated resins were identified by an elemental analysis and thermogravimetric analysis. The each test sample was prepared by diluting the slurry made by wet ball milling the cationic exchange resins and the anionic exchange resins separated as a spherical granular form for 24 hours. The resulting test samples showed a slurry form of less than $75{\mu}m$ of particle size and 25,000ppm of $COD_{cr}$. The decomposition conditions of each test samples from a thermal power plant were obtained with a lab-scale(reactor volume : 220mL) supercritical water oxidation(SCWO) facility. Then pilot plant(reactor volume : 24 L) tests were performed with the test samples from a thermal power plant and a nuclear power plant successively. Based on the optimal decomposition conditions and the operation experiences by lab-scale facility and the pilot plant, a commercial plant(capacity : 150kg/h) can be installed in a nuclear power plant was designed.

• Applied Chemistry for Engineering
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• v.23 no.4
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• pp.372-376
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• 2012

Carbon nanotubes (CNT) are considered as one of ideal nano-fillers in the field of composites with their excellent electrical, mechanical, and thermal properties. Therefore CNT composites are increasingly used in fabricating conductive materials, structural materials with high strength and low weight, and multifunctional materials. The main problem of the CNT composites is difficulty in the dispersion of CNT in the polymer matrix. In this study multi-walled carbon nanotubes (MWNT) were pretreated by the physical process utilizing a wrapping method. After the pretreatment polymer/MWNT nanocomposites were prepared by melt processing. The effect of functionalization MWNT by wrapping with styrene acrylonitrile (SAN) on the mechanical and electrical properties of acrylonitrile butadiene styrene resin (ABS)/MWNT composites was studied by comparing the properties of ABS mixed with the neat MWNT. Electrical and mechanical properties of ABS/MWNT nanocomposites were studied as a function of the functionalization and content of MWNT. The tensile strength of the ABS/MWNT nanocomposites increased, but the impact strength decreased. The polymer wrapping in ABS system has little effect on the improvement of electrical properties.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.39-39
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• 2018

최근 플라즈마 의학이 발달하면서 제트, 펜, 니들, 토치 등의 다양한 형태의 플라즈마 발생기가 개발되었으며 내부의 가스라인으로 가스의 종류, 유속, 조성 등을 조절하여 생물학적 효과를 극대화 할 수 있고 안정적으로 플라즈마 방전상태를 유지할 수 있으나 처리 면적이 좁아 실제 생물학적 시스템 (세포, 조직, 그리고 박테리아) 적용에 있어 한계점이 존재한다. 이러한 한계점을 극복하기 위해서 유전체격벽방전 (Dielectric barrier discharge, DBD) 방식을 이용한 플렉서블 활성종 발생기를 제작하고 생물학적 시스템에 적용하기 위한 방전 특성 평가를 진행하였으며, 간단한 in vitro 모델인 한천 젤을 이용하여 플라즈마 처리에 따른 전달물질의 침투거리를 확인하였다. 플라즈마 방전 시 생성되는 수산화기 [OH], 과산화수소 [$H_2O_2$], 초산소음이온 [$O_2{^-}$], 오존 [$O_3$], 그리고 산화질소 [$NO_x$]와 같은 산소 및 질소 활성종 (Reactive oxygen and nitrogen species, RONS)은 세포벽 또는 세포막의 주요 구성성분인 다당류와 인지질의 과산화 반응을 통해 구조를 변화시키고 생물학적 시스템의 표면의 pH를 낮춘다. 이러한 RONS의 작용은 살균, 소독 뿐만 아니라 약물의 침투를 돕는다. 일반적으로 한천 겔은 농도에 따라 생체 내 뇌 조직과 물리적 특성이 유사하고, 미생물학 기질, 방사선학 연구를 위한 조직모델로 사용되기 때문에 본 연구에서는 3%와 5% 농도의 한천 젤을 사용하여 침투거리를 확인하였다. 한천 젤은 $2.5{\times}2.5{\times}2.5cm^3$의 크기로 준비되었고 대조군으로 염료가 포함된 에멀젼을 0.01 g 도포하고, 실온에서 30분간 보존 후 단면을 잘라 현미경으로 침투거리를 확인하였으며, 실험군으로 플라즈마 전처리 후 에멀젼을 도포한 시표와 에멀젼 도포 후 플라즈마 처리한 시료에 대해 에멀젼 침투거리의 변화를 확인하였다. 본 연구의 플렉서블 활성종 발생기는 인체에 부착하여 사용되기 때문에 화상, 홍반을 유발을 방지하기위해 $40^{\circ}C$의 온도에서 실험을 진행하였고 이때에 플라즈마 방전조건은 $0.065W/cm^2$ 수준의 전력을 소모하는 1.7 kV의 전압, 16 kHz의 주파수로 10분간 처리하였다. 그 결과 3%의 한천 젤의 경우 침투거리 0.779 mm에서 0.826 mm, 0.942 mm까지 침투거리가 증가하였고 5%의 한천 젤의 경우 0.859 mm, 0.949 mm로 증가하였다. 이러한 침투거리 증가는 젤 표면의 다당류를 구성하고 있는 단량체가 플라즈마 처리시 화확적 구조가 끊어져 결론적으로 약물 침투가 증가된 것으로 판단된다.

• The Journal of the Petrological Society of Korea
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• v.25 no.2
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• pp.107-119
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• 2016

Trace element abundances in the igneous rocks are important data for petrogenetic interpretation. Their concentrations are generally measured using ICP-MS from the dissolved solution. The acid digestion of rock powder can be performed by conventional teflon vial or pressure bomb. In this paper, we investigated a problem that happened during acid digestion experiment using conventional teflon vial or pressure bomb of BCR2 and GSP2 USGS rock standard materials. The results show that the measured concentrations of the elements like Cr, Ni, Zn, Ta, W in the BCR2 are different from the recommended values of USGS whereas those of the elements like Rb, Sr, Zr, Hf, Ta, W in the GSP2 are different from those values. Our experiment shows that defect of specific elements like Cr, Ni may happen during the sample digestion. Our results also indicate that the Cr, Ni, W, Zr, Hf, Ta concentration obtained based on an acid digestion of geological samples need to be careful in their geochemical interpretation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.723-727
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• 2002

Conformational changes of allivin, a major allergen protein in garlic, by gamma irradiation were observed. Allium solution (3.0 mg/mL in 0.01 M PBS, pH 7.4) and raw garlic were irradiated in a gamma irradiation facility to be absorbed with doses of 2.5, 5.0, 7.5 and 10.0 kGy. After irradiation, a half of irradiated allivin solution was filtered through 0.22 ${\mu}{\textrm}{m}$ filtration kit. UV spectrum and SDS-PAGE were used for observing the conformational changes of allivin by gamma irradiation. Turbidity of allivin solution was increased by optical observation, and the result was validated by the increase of absorbance at 660 m. Turbidity of irradiated and filtered allivin solution significantly (p<0.05) decreased, and the concentration of soluble protein in the solution decreased by increase of the dose. Aggregation among allivin molecules was observed by SDS-PAGE, but irradiated and filtered samples showed decrease of allivin with reducing aggregation trend. SDS-PAGE profiles of irradiated raw garlic were not different. Results indicate that gamma irradiation can decrease the allivin in solution state which may impact on allergenic reaction of garlic.