• Proceedings of the Korean Environmental Sciences Society Conference
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• 2005.05a
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• pp.313-315
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• 2005

비이온성 계면활성제의 화학적 구조에 따른 리모넨의 유화분산시 입경변화와 세정성을 비교검토한 결과 리모넨과 계면활성제의 사용비가 30:1의 소량을 사용하여도 충분한 세정성을 보였으며, 에스테르 구조를 가진 계면활성제가 유화능력이 우수하여 에멀젼 입경이 작고 접착력은 크며, 접촉각이 작아 가장 우수한 세정성을 나타내었다. 그리고 에테르 구조의 계면활성제간 비교로부터 방향족 고리 구조보다 지방족 사슬구조가 에멀젼의 입경이 작고 세정성이 우수하였다. 에멀젼의 안전성은 에스테르계가 가장 우수하였다.

• Applied Chemistry for Engineering
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• v.4 no.4
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• pp.683-691
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• 1993

All the activities and physical properties including surface tension, foaming power, foam stability, emulsifying power, dispersion effect, wettability and solubilization of sodium dodecyl polyoxyethylene ${\alpha}$-sulfo alkanoates aqueous solution were measured and critical micelle concentration was evaluated. Their cmc ebaluated by the surface tension method was $10^{-4}{\sim}10^{-5}mol/{\ell}$, and surface tension of the aqueous solution was decreased to 30~70dyne/cm. The experimental results for foaming power, foam stability, emulsifying power in benzene or soybean oil, dispersion effect in calcium carbonate, wettability and solubilization showed a good and efficient surface active properties, and then it would be expected that these products could be applied as O/W type emulsifier, dispersion agent.

• Applied Chemistry for Engineering
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• v.21 no.5
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• pp.514-521
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• 2010

A new one-shot process was employed to fabricate proton exchange membranes (PEMs) over conventional solvent-casting process. Here, PEMs containing nano-dispersed silica nanoparticles were fabricated using one-shot process similar to the bulk-molding compounds (BMC). Different components such as reactive dispersant, urethane acrylate nonionmer (UAN), styrene, styrene sulfuric acid and silica nano particles were dissolved in a single solvent dimethyl sulfoxide (DMSO) followed by copolymerization within a mold in the presence of radical initiator. We have successfully studied the water-swelling and proton conductivity of obtained nanocomposite membranes which are strongly depended on the surface property of dispersed silica nano particles. In case of dispersion of hydrophilic silica nanoparticles, the nanocomposite membranes exhibited an increase in water-swelling and a decrease in methanol permeability with almost unchanged proton conductivity compared to neat polymeric membrane. The reverse observations were achieved for hydrophobic silica nanoparticles. Hence, hydrophilic and hydrophobic silica nanoparticles were effectively dispersed in hydrophilic and hydrophobic medium respectively. Hydrophobic silica nanoparticles dispersed in hydrophobic domains of PEMs largely suppressed swelling of hydrophilic domains by absorbing water without interrupting proton conduction occurred in hydrophilic membrane. Consequently, proton conductivity and water-swelling could be freely controlled by simply dispersing silica nanopartilces within the membrane.

• Applied Chemistry for Engineering
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• v.1 no.2
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• pp.224-231
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• 1990

To improve the dispersion of platinum catalyst, the effects of carbon black surface treatment, solvents, surfactants, and ultrasonic homogenizing were examined. Upon introducing the hydrophilic groups acting as an anchorage center of the catalyst on the surface of carbon black by oxidation, the migrating and growing of platinum particles(or ions) during reduction could be restricted. When mixed solvents, surfactants, or ultrasonic homogenizer were used to disperse catalysts on the carbon black, the dispersion of catalyst could be improved, due to the good permeation of chloroplatinic acid through the pore of carbon black. Among the impregnation methods, the method using ultrasonic homogenizer with mixed solvent was the most excellent. Using this method the particle sized could be minimized in less than $30A^{\circ}$ and distributed homogeneously.

• Applied Chemistry for Engineering
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• v.9 no.6
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• pp.846-851
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• 1998

An experimental research on the preparation of zinc oxide fine particles in w/o emulsions was conducted. Precipitation solutions were zinc nitrate aqueous solutions with hexamethylenetetramine(HMTA) as precipitant. The precipitation solutions formed stable w/o emulsions with kerosine in the presence of Span 80. Homogeneous precipitation reaction occurred in the w/o emulsion after the resultant w/o emulsion was heated above the decomposition temperature of HMTA and zinc oxide particles were precipitated. In some case, zinc oxide particles of bi-modal distribution were obtained. However, zinc oxide fine particles of narrow particle size distribution could be obtained, even when the initial zinc concentration of precipitation solution and the conversion to zinc oxide are both higher that those in bulk homogeneous precipitation.

• Korean Chemical Engineering Research
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• v.51 no.3
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• pp.364-369
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• 2013

Oxidative dehydrogenation of n-butane over mesoporous Cr catalysts were studied. Catalysts were prepared by Cr impregnated method over Ti or Zr dispersed mesoporous support such as SBA-15, ${\gamma}$-alumina and characterized by XRD, SEM, TEM, FT-IR UV-Vis and ICP-AES. The effect of high surface area was not noticed appreciably in terms of conversion, but for Cr catalysts with Ti and Zr-incorporated on SBA-15 and ${\gamma}$-alumina. showed high selectivity of trans-2-butene.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.1
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• pp.63-68
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• 2010

CNT and permalloy composite plating was investigated. CNTs were pretreated prior to electroplating to disassemble the tangled CNT lumps. The ball milling as a physical pretreatment and the acid treatment as a chemical pretreatment were used. 10M nitric acid and 10 M sulfuric acid were used for the chemical pretreatment. Sulfuric acid was more effective than nitric acid to disassemble CNT lumps. To disperse CNT in the solution, surfactants were used. SDS, Triton X-100 and PAA were used for this purpose. More CNTs were incorporated in permalloy coating when PAA was used as a surfactant. The surface morphologies were observed with FESEM after electroplating CNT and permalloy. The current densities were varied from 10 to $80\;mA/cm^2$ and the concentration of PAA was fixed at 2 g/L. The optimum current density without surface cracks was $20\;mA/cm^2$. The crystallinity of the deposit was analyzed with XRD and the surface hardness was analyzed with Vicker's hardness tester. The corrosion behavior was analyzed with polarization plot. The physical properties of permalloy were not improved with CNT composite plating.

• Analytical Science and Technology
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• v.5 no.1
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• pp.103-110
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• 1992

Chemical homogeneity and dispersoid formation in mechanically alloyed Al-Ti composite metal powders were investigated in order to fabricate the high temperature Al-Ti alloys. The homogeneity of composite particles was able to be obtained by MA milling time more than 10 hours with the milling velocity of 400 rpm. The amounts of titanium, carbon and oxygen elements in MA Al-Ti alloys by chemical analysis were 8.2, 1.135 and 0.233 wt.%, respectively. The amount of carbon analyzed corresponds to 90 pet. of carbon contained the PCA of stearic acid. TEM analysis has revealed the presence of the rounded $Al_3Ti$ dispersoids with the size of 250nm and the $Al_4C_3$ dispersoids of cylindrical shape with a size of 50nm in thickness and 150nm in length. Also, the some rounded $Al_2O_3$ dispersoids with a size of about 20nm were found in grain boundaries as well as in matrix.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.4
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• pp.293-300
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• 2016

Purpose: The purpose of this study is finding proper bonding agents to be used when adding bis-acryl composite provisional materials. Materials and Methods: Three bonding agents with different chemical compositions were included in this study. Forty disk shaped specimens of bis-acryl composite provisional material were prepared and divided into 4 groups according to the bonding agents. Control group didn't have bonding agent. Through the Teflon mould with 4.0 mm diameter hole with 4.0 mm thickness the same bis-acryl composite provisional material was added on the disks after the surface of each specimen was treated with designated bonding agent according to the manufacturer's instructions. Shear bond test was performed and the fractured surfaces were inspected with a microscope. One-way analysis of variance was conducted and the result was further analysed with Turkey post hoc test at the significance level of 0.05. Results: The highest strength was acquired from the specimens bonded with chemical cure system and it was statistically significant (P < 0.05). This group showed 100% cohesive failures. The lowest bonding strength was recorded from the specimens used conventional light cure bonding agent, and this group's result was similar with the control group. The group used a light cure bonding agent claiming improved compatibility revealed significantly higher bond strength to the traditional light cure bonding agent group in a statistically significant way (P = 0.043). Conclusion: According to the bonding agent used the shear bond strength was significantly affected. Therefore the choice of proper bonding agent is important when hiring a bonding agent to add bis-acryl composite provisional materials.

• Applied Chemistry for Engineering
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• v.22 no.3
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• pp.272-276
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• 2011

The separation of metallic and semiconducting single-wall carbon nanobubes (SWCNTs) by agarose gel method was carried out in this study. The effect of concentration of agarose, SDS (sodium dodecyl sulfate), and pH in the solution on separation behavior was investigated. With increasing the concentration of agarose in the solution, it showed that the ratio of metallic SWCNTs, which was analyzed from UV-vis-NIR spectroscopy, was increased in the solution phase, while the overall concentration of SWCNTs was decreased. With increasing the concentration of SDS, we could observe that the ratio of metallic SWCNTs was increased due to more affinity between SDS molecules and metallic SWCNT. The highest metallic SWCNTs ratio was reached up to 58.4% when the pH of solution was 8.2.