• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.588-594
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• 1997

Gelation time, gel structure and volatility of by-products during gelation of PZT sol-gel processing were investigated by FT-IR spectroscopy. FT-IR spectroscopic study was performed on PZT gels with the various H₂O contents (1, 2 and 3 mol) and the several types (HNO₃, NH₄OH) and amounts (0.1, 0.2 mol) of catalysts, monitoring temporal (0, 1, 3, 10 weeks, 3 months and 3 years) and thermal (100-700 ℃) changes of FT-IR spectra. The interpretation of temporal change of the spectra revealed two trends. One is under the condition of 1 mol H₂O, 1 mol H₂O+0.1 mol HNO₃, 3 mol H₂O and the other is for 1 mol H₂O+0.1 mol NH₄OH, 2 mol H₂O, 1 mol H₂O+0.2 mol HNO₃. The gel structures and the gelation times for these conditions were discussed in comparison with the reported results of SiO₂, and we suggested the reaction mechanisms for these structural characteristics. Thermal variation of FT-IR spectra was interpreted as the evolution processes of gel by investigating the evaporation of solvent and the decomposition of organic residues.

• Journal of the Korean institute of surface engineering
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• v.52 no.2
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• pp.96-102
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• 2019

Magnesium and its alloys are prone to be corroded, thus surface treatments improving corrosion resistance are always required for practical applications. As a surface treatment of magnesium alloys, plasma electrolytic oxidation (PEO), creating porous stable oxide layer by a high voltage discharge in electrolyte, enhances the corrosion resistance. However, due to superhydrophilicity of the porous oxide layer, which easily allow the penetration of corrosive media toward magnesium alloys substrate, post-treatments inhibiting the transfer of corrosive media in porous oxide layer are required. In this work, we employed a hydrophobizing method to enhance the corrosion resistance of PEO treated Mg alloy. Three types of hydrophobizing techniques were used for PEO layer. Thin Teflon coating with solvent evaporation, self-assembled monolayer (SAM) coating of octadecyltrichlorosilane (OTS) based on solution method and SAM coating of perfluorodecyltrichlorosilane (FDTS) based on vacuum method significantly enhances corrosion resistance of PEO treated Mg alloy with reducing the contact of water on the surface. In particular, the vacuum based FDTS coating on PEO layer shows the most effective hydrophobicity with the highest corrosion resistance.

• Membrane and Water Treatment
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• v.10 no.6
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• pp.441-449
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• 2019

In this study, cellulose acetate (CA) / nylon66 (NYL66) (95/5) blend membranes with different thicknesses were prepared by a solvent evaporation method. The effects of membrane thickness (almost $7-25{\mu}m$), feed concentration (70-95 wt.% isopropanol), and feed temperature ($30-60^{\circ}C$) were investigated on the performance of membrane in the separation of isopropanol-water mixtures. With regard to the results of sorption experiments, it was found that the increase of feed temperature enhanced the overall sorption while by increasing feed concentration, the overall sorption passed through a maximum value at 70 wt. % isopropanol (IPA). The best separation factor 3080.51 was gained at high isopropanol concentration 95 wt.%, low feed temperature $30^{\circ}C$, and high membrane thickness $24.62{\mu}m$. Regarding the pervaporation separation index, the obtained results showed that proper values for the thickness of membrane, feed temperature, and isopropanol concentration in feed were $24.62{\mu}m$, $40^{\circ}C$, and 70 wt.%, respectively.

• Resources Recycling
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• v.15 no.5 s.73
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• pp.26-32
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• 2006

The waste solution discharged from the LCD manufacturing process contains acids like nitric, acetic and phosphoric acid and metal ions such as Al, Mo and other impurities. It is important to remove impurities less than 1 ppm in phosphoric acid to reuse as an etchant because the residual impurities even in sub-ppm concentration in semiconductor materials play a major role on the electronic properties. In this study, a mixed system of solvent extraction, diffusion dialysis and ion-exchange was developed to commercialize in an efficient system fur recovering the high-purity phosphoric acid. By vacuum evaporation, almost 99% of nitric and acetic acid was removed. And by solvent extraction method with tri-octyl phosphate (TOP) as an extractant, the removal of acetic and nitric acid from the acid mixture was achieved effectively at the ratio A/O=1/3 with 4th stage of extraction stage. About 97.5% of Al and 36.7% of Mo were removed by diffusion dialysis. Essentially almost complete removal of metal ions and purification of high-purity phosphoric acid could be obtained by using ion exchange.

• Membrane Journal
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• v.28 no.3
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• pp.187-195
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• 2018

In this work, the morphology of polyvinylidene-co-hexafluoropropylene (PVDF-co-HFP) membranes were systemically investigated using phase inversion technique, to target membrane contactor applications. As the presence of macrovoids degrade the mechanical integrity of the membranes and jeopardize the long-term stability of membrane contactor processes (e.g. wetting), a wide range of dope compositions and casting conditions was studied to eliminate the undesired macrovoids. The type of solvent had significant effect on the membrane morphology, and the observed morphology were correlated to the physical properties of the solvent and solvent-polymer interactions. In addition, to fabricate macrovoid-free structure, the effects of different coagulation temperatures, inclusion of additives, and addition of nonsolvents were investigated. Due to the slow crystallization rate of P(VDF-co-HFP) polymer, it was found that obtaining porous membrane without macrovoids is difficult using only nonsolvent-induced phase separation method (NIPS). However, combined other phase inversion methods such as evaporation-induced phase separation (EIPS) and vapor-induced phase separation (VIPS), the desired membrane morphology can be obtained without any macrovoids.

• Analytical Science and Technology
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• v.6 no.5
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• pp.521-530
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• 1993

According to the Montreal Protocol, CFC 113, one of the ozone-depleting substances, will be prohibited to use as a cleaning solvent essentially in the electronic industry. Therefore, the development of the alternative cleaning solvents to CFC 113 is being accelerated. A number of the alternative cleaning solvents are avialable on the market. The alternatives of Axarel 32(DuPont), Cleanthru 750H(KAO Chemical), and EC-Ultra(Petroferm) are chosen for the comparison of cleaning performance with CFC 113. The test methods for measuring the cleaning performance were composed of the measurement of the physical properties, the experiments on the material compatibility with cleaning solvents, the measurement of the evaporation rate, and finally the experiments of the removal efficiency. Normally the basic physical properties of the alternatives had higher boiling points, viscosity and surface tension, which were quite different to those of CFC 113. In terms of solubility of rosin-based flux, the solubilities of abietic acid (nonpolar organic) were similar, but those of the activator (polar organic) in the alternatives were better than CFC 113. The evaporation of the alternatives was very slow, compared to CFC 113, which had much lower boiling point. All the cleaning solvents showed the good material compatibility with FR4 and Cu-coated PCB. The better removal efficiencies of abietic acid were obtained when using the ultrasonic mechanical energy over the dipping method. The experiments also indicated the very slow-eavaporating solvent was not desirable with the dipping cleaning method, and the differences in the removal efficiency of the alternatives with the ultrasonic cleaning method were negligible. Among the alternatives, the overall cleaning performances were obsorved as almost similar. Before selecting the ultimate cleaning solvent, the application of cleaning machine, environmental issues, and economics are simultaneously considered with the cleaning performance.

• Applied Biological Chemistry
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• v.12
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• pp.89-97
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• 1969

These studies were made on coating of fresh fruits and vegetables with PVC under view on preservation of fresh fruits and vegetables due to restrain water evaporation of them and control gas metabolisms. The results obtained, as selection of PVC materials availble for preservation of them, procedure of the coating, useful organic solvents, concentration of PVC solution and the time of dipping, and effects of the preservation of them, were summarized as follows: 1) PVC powder 222 and PVC powder 443 were surveyed as suitable materials for coating apple, and later was excellent in lustrous aspect. 2) The coating procedure which dipt into PVC solution was suitable to treat much within a short space of time, and using of ventillator accelerate rather evaporation of the organic solvent. 3) Aceton and methyethylketon as solvent of the PVC were, in purpose of storage only, avaible, while aceton was, in view ef taste, better. 4) 10% of the PVC solutions were better to preserve the freshness of apple and 5, 4, 1 and 0.5% of them in order were gradually decreased in preservability, and 15% of them as high concentration were looked like fermentation in one week after the coating. 5) The dipping time was also better n minute than 10 seconds in a preservation but 1-2 minutes could be applied owing to be not affected of the taste due to coating. 6) The freshness of treatment groups were extend about 48 days after coating in room temperature but control lost market value with 12 days. 7) Weight of control was decreased to 10-13% but treatment which was dipped into 10% of coating solution for one minute was decreased to 3.5-4.6% and treatment for four minutes was did to 2.9-3.0%. 8) Change in respiration was less is treatment groups than control in exhaustion of $CO_2$, and water soluble sugar, reduced sugar and pH were not changed almost due to coating. 9) Pannel discussion of the taste was indicated that control was better than treatments soon after coating, but treatments were rather than control last period of storage and treatment with aceton solvent specially was better than others.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.255-255
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• 2016

Resistive random access memory (ReRAM)는 낮은 동작 전압, 빠른 동작 속도, 고집적화 등의 장점으로 인해 차세대 비휘발성 메모리 소자로써 많은 관심을 받고 있다. 최근에 ReRAM 절연막으로 NiOx, TiOx, AlOx TaOx, HfOx와 같은 binary metal oxide 물질들을 적용하는 연구가 활발히 진행되고 있다. 특히, HfOx는 안정적인 동작 특성을 나타낸다는 점에서 ReRAM 절연막 물질로 적합하다고 보고되고 있다. ReRAM 절연막을 형성할 때, 물리 기상 증착 방법 (PVD)이나 화학 기상 증착법 (CVD)과 같은 방법이 많이 이용된다. 이러한 증착 방법들은 고품질의 박막을 형성시킬 수 있는 장점이 있다. 하지만, 높은 온도에서의 공정과 고가의 진공 장비가 이용되기 때문에 경제적인 문제가 있으며, 기판 또는 금속에 플라즈마 손상으로 인한 문제가 발생할 수 있다. 따라서 이러한 문제점들을 개선하기 위해 용액 공정이 많은 관심을 받고 있다. 용액 공정은 공정과정이 간단할 뿐만 아니라 소자의 대면적화가 가능하고 공정온도가 낮으며 고가의 진공장비가 필요하지 않은 장점을 가진다. 따라서 본 연구에서는, 용액공정을 이용하여 HfOx 기반의 ReRAM 제작하였고 $25^{\circ}C$와 $85^{\circ}C$에서 ReRAM의 동작특성에 미치는 compliance current의 영향을 평가하였다. 실험 방법으로는, hafnium chloride (0.1 M)를 2-methoxyethanol에 충분히 용해시켜서 precursor를 제작하였다. 이후, p-type Si 기판 위에 습식산화를 통하여 300 nm 두께의 SiO2 절연층을 성장시킨 후, 하부전극을 형성하기 위해 electron beam evaporation을 이용하여 10/100 nm 두께의 Ti/Pt 전극을 증착하였다. 순차적으로, 제작된 산화물 precursor를 이용하여 Pt 위에 spin coating 방법으로 1000 rpm 10 초, 6000 rpm 30초의 조건으로 두께 35 nm의 HfOx 막을 증착하였다. 최종적으로, solvent 및 불순물을 제거하기 위해 $180^{\circ}C$의 온도에서 10 분 동안 열처리를 진행하였으며, 상부 전극을 형성하기 위해 electron beam evaporation을 이용하여 Ti와 Al을 각각 50 nm, 100 nm의 두께로 증착하였다. ReRAM 동작에서 compliance current가 미치는 영향을 평가하기 위하여 compliance current를 10mA에서 1mA까지 변화시키면서 측정한 결과, $25^{\circ}C$에서는 compliance current의 크기와 상관없이 일정한 메모리 윈도우와 우수한 endurance 특성을 얻는 것을 확인하였다. 한편, $85^{\circ}C$의 고온에서 측정한 경우에는 1mA의 compliance current를 적용하였을 때, $25^{\circ}C$에서 측정된 메모리 윈도우 크기를 비슷하게 유지하면서 더 우수한 endurance 특성을 얻는 것을 확인하였다. 결과적으로, 용액공정 방법으로 제작된 ReRAM을 측정하는데 있어서 compliance current를 줄이면 보다 우수한 endurance 특성을 얻을 수 있으며, ReRAM 소자의 전력소비감소에 효과적이라고 기대된다.

• Food Science and Preservation
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• v.12 no.6
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• pp.600-607
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• 2005

This study was conducted to prepare high quality grape seed oils by solvent extraction and chemical refining process. Additionally, quantitative analysis of several functional components in grope seed was carried out to compare quality characteristics of grape seeds from grapes grown by conventional and organic agricultural practices. There are no significant differences in several functional constituents of grape seeds between conventionally cultivated- and organically cultivated-grapes, although some functional compositions of grape seeds are different between two cultivation methods. The dried grape seed was pretreated with roasting heating for 5 min, milled and then extracted twice with n-hexane under reflux at $50^{\circ}C$ for overnight, followed by filtration and evaporation. The crude grape seed oil was successively purified by degumming with $0.1\%\;H_3PO_4$, deaciding with $20\%\;NaOH$, and then decoloring and deodorization by a steam distillation, and thereby producing purified grape seed oil(yield: $5.0\%/dried$ grape seed). Physicochemical characteristics of the purified grape seed oil were comparable to those of the imported grape seed oils.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.8
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• pp.403-409
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• 2018

Inconel 713C which of a commercial Ni super alloy have the composition of 70 % Ni, 12 % Cr, 6 % Al and 4 % Mo. Mo is very expensive and have some economic value to recover in the alloy. In this study, liquid-liquid exraction(solvent extraction and stripping) has been performed to separate Mo from the synthetic leaching solution of spent Inconel 713C alloy and prepare to Mo powder by dying, evaporation and heat treatment. The experiments were conducted by using synthetic leaching solution which was prepared $NaMoO_4$ $2H_2O$ by dissolved in distilled water. Alamine336 and Cyanex272 dissolved in kerosene were used as extractants. The extraction percentage of Mo by Alamine336 is 99 % in the condition of the range of pH 1 to 4 and 1 % of concentration of Alamine336. The stripping solutions are used by HCl, $H_2SO_4$ and $HNO_3$ solutions and the concentrations were controlled by distilled water. The concentrations of HCl, $H_2SO_4$ and $HNO_3$ as stripping solutions are increased, the stripping percentages of Mo are increased and the stripping percentage of Mo by $HNO_3$ is higher than other stripping solutions. After liquid-liquid extraction and heat treatment, $MoO_3$ powder which of the purity of 97.5 % was prepared.