• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.16 no.12S
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• pp.1181-1186
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• 2003

Chemical Mechanical Polishing (CMP) is an essential dielectric planarization in multilayer microelectronic device fabrication. In the CMP process, it is necessary to minimize the extent of surface defect formation while maintaining good planarity and optimal material removal rates. The polishing mechanism of W-CMP process has been reported as the repeated process of passive layer formation by oxidizer and abrasion action by slurry abrasives. Thus, it is important to understand the effect of oxidizer on W passivation layer, in order to obtain higher removal rate (RR) and very low non-uniformity (NU %) during W-CMP process. In this paper, we compared the effects of oxidizer or W-CMP process with three different kind of oxidizers with 5 wt% hydrogen peroxide such as Fe(NO$_3$)$_3$, H$_2$O$_2$, and KIO$_3$. The difference in removal rate and roughness of W in stable and unstable slurries are believed to caused by modification in the mechanical behavior of Al$_2$O$_3$ particles in presence of surfactant stabilizing the slurry.

• Polymer(Korea)
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• v.25 no.4
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• pp.528-535
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• 2001

Polyurethane specimens were mainly composed of polyol, MDI, silicone surfactant, and water. The effects of ethylene glycol on the cell size, forming magnification, cream time, gel time, take free time, final free rising height, and reactive temperature were investigated. The cyclopentane was used for PU foam as a physical blowing agent. The components were hand-mixed at about 5000 rpm within 4 seconds at room temperature. The mixtures with various ethylene glycol contents were foamed in the wood mold. When the index of isocyanate was fixed, as the amount of ethylene glycol increased, cell size and thermal conductivity were decreased by about 5.1% and 14%, respectively.

• Journal of Environmental Science International
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• v.22 no.7
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• pp.837-845
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• 2013

This study was designed to synthesize mesoporous carbon, porous carbonic material and to characterize its surface in an attempt to adsorption methane gas($CH_4$). Synthesis of mesoporous carbon was carried out under two steps ; 1. forming a RF-silica complex with a mold using CTMABr, a surfactant, and TEOS, raw material of silica, and 2. eliminating silica through carbonization and HF treatment. The mesoporous carbon was synthesized under various conditions of synthesis time and calcination. Eight different types of mesoporous carbon, which were designated as MC1, MC2, MC3, MC4, MCT1, MCT2, MCT3, and MCT4, were prepared depending upon preparation conditions. The analysis of mesoporous carbon characteristics showed that the calcination of silica stabilized the mixed structure of silica and carbonic complex, and made the particle uniform. The results also showed that hydrothermal synthesis time did not have a strong influence on the size of pore. The bigger specific surface area was obtained as the hydrothermal synthesis time was extended. However, the specific surface area was getting smaller again after a certain period of time. In adsorption experiments, $CH_4$ was used as adsorbate. For the case of $CH_4$, MCT3 showed the highest adsorption efficiency.

• Journal of the Korean Ceramic Society
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• v.45 no.1
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• pp.48-53
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• 2008

In order to reduce signal delay in ULSI, an intermetal material of low dielectric constant is required. Ordered mesoporous silica film is proper to intermetal dielectric due to its low dielectric constant and superior mechanical properties. The ordered mesoporous silica film prepared by TEOS (tetraethoxysilane) / MTES (methyltriethoxysilane) mixed silica precursor and Brij-76 surfactant was surface-modified by HMDS (hexamethyldisilazane) treatment to reduce its dielectric constant. HMDS can substitute $-Si(CH_3)_3$ groups for -OH groups on the surface of silica wall. In order to modify interior silica wall, HMDS was treated by two different processes except the conventional spin coating. One process is that film is dipped and stirred in HMDS/n-hexane solution, and the other process is that film is exposed to evaporated HMDS. Through the investigation with different HMDS treatment, it was concluded that surface modification in evaporated HMDS was more effective to modify interior silica wall of nano-sized pores.

• Bulletin of the Korean Chemical Society
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• v.16 no.7
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• pp.582-588
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• 1995

The preconcentration and determination of trace Cd(Ⅱ), Cu(Ⅱ), Pb(Ⅱ), Mn(Ⅱ) and Zn(Ⅱ) in water samples were studied by the precipitate flotation using La(OH)3 as a coprecipitant. The analytes were quantitatively coprecipitated by adding 3.0 mL of 0.1 M La(Ⅲ) solution in a 1,000 mL water sample and adjusting the pH to 9.5 with NaOH solution. After the addition of the 1:8 mixed surfactant solution of each 0.1% sodium oleate and sodium lauryl sulfate, the solution was stirred with a magnetic stirrer for 10 minutes. The precipitates were floated to the surface by bubbling with nitrogen gas and collected in a small sampling bottle. The precipitates were dissolved in nitric acid and then the solutions were diluted to 25.00 mL with a deionized water. The analytes were determined by flame atomic absorption spectrometry. This procedure was applied to the waste water analysis. This technique was simple, convenient and especially rapid for the analysis of a large volume of sample. And also, from the recoveries of better than 92% which were obtained from real samples, this method could be judged to be applicable to the preconcentration and quantitative determination of trace elements in water samples.

• Journal of Life Science
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• v.17 no.12
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• pp.1660-1668
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• 2007

The non-ionic surfactant (NIS) Tween 80 was evaluated for its ability to influence invitro cumulative gas production, dry matter digestibility, cellulolytic enzyme activities, anaerobic microbial growth rates, and adhesion to substrates by mixed rumen microorganisms on rice straw, alfalfa hay, cellulose filter paper and tall fescue hay. The addition of NIS Tween 80 at a level of 0.05% increased significantly (P<0.05) in vitro DM digestibility, cumulative gas production, microbial growth rate and cellulolytic enzyme activity from all of substrates used in this study. In vitro cumulative gas production from the NIS-treated substrates; rice straw, alfalfa hay, filter paper and tall fescue hay was significantly (P<0.05) improved by 274.8, 235.2, 231.1 and 719.5% compared with the control, when substrates were incubated for 48 hr in vitro. The addition of 0.05% NIS Tween 80 to cultures growing on alfalfa hay resulted in a significant increase in CMCase (38.1%), xylanase (121.4%), Avicelase (not changed) and amylase (38.2%) activities after 36 h incubation. These results indicated that the addition of 0.05% Tween 80 could greatly stimulate the release of some kinds of cellulolytic enzymes without decreasing cell growth rate in contrast to trends reported with aerobic microorganism. Our SEM observation showed that NIS Tween. 80 did not influence the microbial adhesion to substrates used in the study. Present data clearly show that improved gas production, DM digestibility and cellulolytic enzyme activity by Tween 80 is not due to increased bacterial adhesion on the substrates.

• KSBB Journal
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• v.14 no.4
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• pp.445-451
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• 1999

Glutathione production was carried out using mixed cells of E. coli TG1/pDG7 $\alpha$ and bakers yeast in an Aerated Slurry Bioreactor. Glutathione-producing enzymes were stable for 34 hours, yielding 4.6 mM glutathione in suspension reaction. Glutahione production with high density mixed cells was studied as a function of flow rate in an Aereated Slurry Bioreactor. Glutathione concentration was higher than that in suspension reaction for 32 hours at the substrate feeding rate of 5.2 mL/hr with cell recycle in continuous Aerated Slurry Bioreactor. It was for 42 hours at 2.6 mL/hr and 22 hours at 5.2 mL/hr without cell recycle. Glutahione productivity was 25.7 mg/g wet $cell{\cdot}hr$ at the substrate feeding rate of 10.4 mL/hr with cell recycle, but 5.28 mg/g wet $cell{\cdot}hr$ at 5.2 mL/hr and 1.65 mg/g wet $cell{\cdot}hr$ at 2.6 mL/hr without cell recycle. Effective production time increased from 25 to 45 hours, by using a surfactant, tween 80. As a purfing gas, nitrogen was tested instead of air to avoid a possible oxidizing effect on glutathione-producing enzymes, resulting in the increase of effective production time to 40 hours.

• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.118-124
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• 2009

The values of critical micelle concentration (CMC) and counter ion binding constants (B) in a micellar state of CPC (1-hexadecylpyridinium chloride) with Brij 35 (polyoxyethylene(23) lauryl ether) in water were determined as a function of ${\alpha}_1$ (the overall mole fraction of CPC) by the use of electric conductivity method. Various thermodynamic parameters ($X_i,\;{\gamma}_i,\;C_i,\;a_{i}^{M},\;\beta,\;and\;{\Delta}H_{mix}$) were calculated and analyzed by means of the equations derived from the non-ideal mixed micellar model. And thermodynamic parameters (${\Delta}{G^o}_m,\;{\Delta}{H^o}_m,\;and\;{\Delta}{S^o}_m$) for the micellization of CPC/Brij 35 mixtures were also calculated from the temperature dependence of the CMC values. The values of ${\Delta}{G^o}_m$ are all negative, but the values of ${\Delta}{S^o}_m$ and ${\Delta}{H^o}_m$ are positive or negative, depending on the measured temperature and ${\alpha}_1$.

• Journal of the Korean Society of Urban Environment
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• v.18 no.4
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• pp.429-437
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• 2018

In this study, the mixed toxicity of heavy metals (Cu, Pb, Hg) and surfactants (SLS, ALS) was evaluated by using Vibrio fischeri and Daphnia magna. The sensitivity of ecotoxicity to heavy metals was sensitive to daphnia but the case of surfactants were more sensitive to Vibrio fischeri. Experimental results of Vibrio fischeri show that the toxicity value P(O) was lower than the predicted value P(E), and the antagonistic effect was observed when the heavy metal and the surfactant were mixed. It seems that SLS and ALS, which are anionic surfactants, have anionic form on the hydrophilic head, so that they have an antagonistic effect that they are bonded with heavy metal ion which is a cation type and the actual toxicity is lowered. In Daphnia magna, the results showed that antagonistic, additive and synergistic effects were in order as concentrations increased. As the concentration increases, Daphnia magna, which is highly sensitive to heavy metals, seems to have a synergistic effect with a rapid increase in mortality.

• Journal of Soil and Groundwater Environment
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• v.11 no.2
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• pp.13-21
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• 2006

Polycyclic aromatic hydrocarbons (PAHs) are widespread soil contaminants and major environmental concerns. PAHs have extremely low water solubility and are strongly sorbed to soil. A potential technology for remediation of PAHcontaminated soils is a soil washing with surfactant solutions. While the use of surfactants significantly enhances the performance of soil remediation, operation costs are increased. Selective adsorption of PAHs by activated carbons is proposed to reuse the surfactants in the soil-washing process. The adsorption isotherms of pure chemicals (Triton X-100 and phenanthrene) onto three granular activated carbons were obtained. The selective adsorption of phenanthrene in mixed solution was examined at various concentrations of phenanthrene and Triton X-100. The selectivity results were discussed with pore size distribution of activated carbons and molecular sizes of phenanthrene and the Triton X-100 monomer. The selectivity for phenanthrene was much larger than 1 regardless of the particle size of activated carbons. The selective adsorption using activated carbons with proper pore size distribution would greatly reduce the material cost for the soil washing process by the reuse of the surfactants.