• 자원리싸이클링
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• 제25권1호
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• pp.60-67
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• 2016

망간단괴 매트상 침출액 조성으로 제조 된 모의 용액(Cu 10.5 g/L, Co 2.0 g/L, Ni 15.0 g/L, Fe 0.2 g/L)으로부터 용매추출-전해채취 연속공정을 통해 구리를 분리-회수하기 위하여 규모 확대용 용매추출장치인 6단 혼합-침강기(mixer-settler : 추출 4단, 탈거 2단)와 전해조를 이용하였다. 용매추출의 경우 추출제로는 40%(v/v)의 LIX 84I, 탈거용액은 전해폐액(Cu 35.0 g/L, $H_2SO_4$ 180 g/L)을 사용하였으며 추출단과 탈거단의 O/A 비는 각각 1/1과 1.5/1 이었다. 용매추출공정의 구리의 추출율과 탈거율은 각각 96.7%와 91.0%이었으며 탈거액(전해액)의 구리, 니켈, 코발트 그리고 철의 농도는 각각 50~51 g/L, 25 ppm, 5 ppm 그리고 3 ppm 이었다. 전해채취공정은 $1.50A/dm^2$의 전류밀도에서 98.9%의 전류효율을 나타내었으며, 99.833% 순도의 금속 구리를 얻었다.

• 한국세라믹학회지
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• 제29권12호
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• pp.997-1003
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• 1992

Ultra-fine hydroxyapatite powders were synthesized by the hydrothermal reaction of Ca(OH)2 suspension or Ca(NO3)2$.$4H2O solution with (NH4)2HPO4 solution, and the powders were characterized for each synthetic condition. Crystalline hydroxyapatite powders have average grain size of less than 50 nm. By increasing the reaction pressure, the crystallinity was improved, and the crystals were preferentially growing along c-axis. When Ca(NO3)2$.$4H2O of high solubility was used, hydroxyapatite of single phase was produced. However when Ca(OH)2 of low solubility was used more than 0.334 mol/ι, unreacted Ca(OH)2 remained. Diffraction spot patterns of transmission electron microscope show that powders synthesized by the hydrothermal reaction were composed of single crystals of hexagonal phase.

• Macromolecular Research
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• 제11권6호
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• pp.495-500
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• 2003

UV-induced graft polymerization of glycidyl methacrylate (GMA) to a polypropylene (PP) membrane was carried out in the vapor phase with benzophenone (BP) as a photoinitiator. Attenuated total reflection Fourier transform infrared spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM) were utilized to characterize the copolymer. The degree of grafting increased with increasing reaction time, increased UV irradiation source intensity, and increased immersion concentration of the BP solution. The optimum synthetic condition for the PP-g-GMA membrane was obtained with a reaction time of 2 hrs, a UV irradiation source intensity of 450 W, and an immersion concentration of the BP solution of 0.5 mol/L. The pure water flux decreased upon increasing the degree of grafting and increasing the amount of diethylamino functional group introduced. The analysis of AFM and SEM images shows that the graft chains and diethylamino groups of PP-g-GMA grew on the PP membrane surface, resulting in a change in surface morphology.

• 한국전기전자재료학회논문지
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• 제18권10호
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• pp.929-935
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• 2005

In this paper, synthetic conditions of titania nanparticle was investigated to enhance its uniformity of the particle size as a child particle on organic mother particle of liquid powder type electronic paper. The physical properties are very important to improve the uniformity of electrical charging properties Concentration of titania raw material ($C_9H_{19}NO_4Ti$) in the ethanol solvent, pH, and concentration of the solution in the D.I. water were selected as parameters. As a result, ultrafine and well crystallized titania nanoparticle with good uniformity could be synthesized as the concentration of the $C_9H_{19}NO_4Ti$ in the ethanol solvent, pH of the solution, and the amount of the D.I. water were increased. Using the optimized conditions, the titania nanparoticle with uniformly ultrafime size of 10 nm could be synthesized.

• 한국암석학회:학술대회논문집
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• 한국암석학회 1999년도 춘계학술대회
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• pp.25-29
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• 1999

Manganese (Mn) oxides in soils and sediments differ in structure and composition. The influence of that diversity on the chromium (Cr) oxidation is the subject of this report. Oxidation of Cr(III) to Cr(VI) by coarse clay size Mn oxides (synthetic pyrolusite and natural lithiophorite, todorokite, and bimessite) was studied. Chromium oxidation by Mn oxides was initially fast and followed by a slow reaction. More Cr was oxidized by the Mn oxides at lower pH and higher initial Cr(III) concentration in solution. Birnessite had the highest chromium oxidation capacity per unit external surface area (COCUESA) and lithiophorite had the lowest COCUESA. The kinetics of Cr oxidation and COCUESA of Mn oixdes were apparently controlled by reactivity of surface Mn, mineralogy, and solution properties (pH and Cr(III) concentration).

• 한국환경과학회지
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• 제12권1호
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• pp.87-92
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• 2003

Synchronous spectrofluorimetry was carried out for the simultaneous determination of various polycyclic aromatic hydrocarbons(PAHs) in aqueous solution by fluorescence spectrometry have been studied. The optimal wavelength interval(${\triangle}{\lambda}$) for synchronous spectra of acenaphthene, anthracene, benzo[a]anthracene, fluorene and pyrene were investigated in the presence of surfactants. The great enhancement of the fluorescence of these PAHs in Triton X-100 was obtained and optimal wavelength was 50 nm. The calibration curves in synthetic mixture solution of 5 PAHs were linear over the range from $1.0{\times}10^{-8}M$ to $1.0{\tiems}10^{-4}M$. Under the optimal experimental conditions, the detection limits were $4.9{\tiems}10^{-9}M$,\;7.0{\times}10^{-9}M,\;4.7{\tiems}10^{-9}M,\;1.6{\tiems}10^{-9}M$ and $3.2{\tiems}10^{-9}M$ for acenaphthene, anthracene, benzo[a]anthracene, fluorene and pyrene, respectively.

• 한국의류학회지
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• 제28권9_10호
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• pp.1312-1319
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• 2004

Underwear is laundered frequently and most of them is made of cotton, but a cotton fiber is more difficult to modify than a synthetic fiber. We have attempted to determine the optimum conditions necessary whereby the lowest concentration of silver solution is needed to produce the greatest antimicrobial properties of cotton fabrics. For this study, colloidal silver was made by electrolysis. The concentration of colloidal silver was increased by increasing the area of the silver plates submerged in the water, the water temperature, the water hardness and the flow time of the water per 1l. However, the colloidal silver concentration was decreased by extending a space between the silver plates and increasing the water velocity. Cotton fabrics treated in the washing machine with 1.3 ppm colloidal silver solution for 10 minutes had effective microbial properties and an unperceivable reduction of reflectance.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2007년도 공동학술대회 논문집
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• pp.167-172
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• 2007

The frequency-domain small-loop electromagnetic (EM) instruments are increasingly used for shallow environmental and geotechnical surveys because of their portability and speed. However, it is well known that the data quality is generally so poor that quantitative interpretation of the data is not justified in many cases. We present an inversion method that allows the correction for the calibration errors and also constructs multidimensional resistivity models. The key point in this method is that the data are collected at least at two different heights. The forward modeling used in the inversion is based on an efficient 3-D finite-difference method, and its solution was checked against 2-D finite-element solution. The synthetic and real data examples demonstrate that the joint inversion recovers reliable resistivity models from multi-frequency data severely contaminated by the calibration errors.

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.173-176
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• 2014

The hollow $SiO_2$ spheres with uniform size were synthesized by a modified Stober method under the control of polyelectrolytes (PSS and PAA) as templates. This synthetic route includes the formation of spherical colloid micelle in ethanol solution, hydrolysis of TEOS under control of ammonia, and the removal of polyelectrolyte by washing or calcination. Hollow silica spheres with controllable core diameters between 100 and 270 nm and wall thickness between 15 and 50 nm have been synthesized. The influence of template solution concentration and solvent and dispersant on the formation of silica hollow spheres is studied and reported in detail.

• 멤브레인
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• 제6권4호
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• pp.273-283
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• 1996

Polystyrene(PS)과 poly(sodium 4-styrene sulfonate)(PSS)를 이용하여 양이온 교환분리막을 제조하였다. PS 분리막은 divinylbenzene(DVB)의 양에 의하여 가교도를 조절하였으며, 이때 casting 용액 내의 PSS 농도를 변화하여 그 구조를 관찰하였다. PS-DVB RO 분리막이 PSS의 첨가에 의하여 MF 용도로 활용될 수 있음을 보여 주었으며, PSS의 sulfonate group으로 인하여 투과수의 증가를 보여주었다. DVB 5%, PSS 3%의 casting 용액으로부터 최적의 MF 구조를 갖는 분리막이 제조되었다.