• Korean Journal of Food Science and Technology
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• v.26 no.5
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• pp.484-489
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• 1994

Solubilization of plant ceil wall(tofu-residue) using enzyme complex obtained by Aspergillus niger CF-34 was attempted. The hydrolysis reaction was done at pH 4.0, $50^{\circ}C$, which were optimum pH and temperature of the enzyme, respectively. At the enzyme dosage of 2.5% (in terms of solid content of tofu-residue) and reaction time of 3 hr, the solubilizing percent of protein and carbohydrate were 62% and 50% respectively. Homogenization prior to enzyme reaction did not have much effect on tofu-residue solubilization. To improve solubility of tofu-residue, additional treatment such as alkali with 0.1% NaOH solution was found to be useful. The results showed that tofu-residue, which mainly consists of cell wall component of cellulose and hemicellulose, was not accessible to enzyme reaction and some prior treatment is required to enhance enzyme hydrolysis.

• Membrane Journal
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• v.27 no.6
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• pp.499-505
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• 2017

The increasing number of natural disasters resulting from anthropogenic greenhouse gas emissions has prompted the development of a gas separation membrane. Carbon dioxide ($CO_2$) is the main cause of global warming. Organic polymeric membranes with inherent flexibility are good candidates for use in gas separation membranes and poly(dimethyl siloxane)(PDMS) specifically is a promising material due to its inherently high $CO_2$ diffusivity. In addition, poly(vinyl pyrrolidine)(PVP) is a polymer with high $CO_2$ solubility that could be incorporated into a gas separation membrane. In this study, poly(dimethyl siloxane)-poly(vinyl pyrrolidine)(PDMS-PVP) comb copolymers with different compositions were synthesized under mild conditions via a simple one step free radical polymerization. The copolymerization of PDMS and PVP was characterized by FTIR. The morphology and thermal behavior of the produced polymers were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Composite membranes composed of PDMS-PVP on a microporous polysulfone substrate layer were prepared and their $CO_2$ separation properties were subsequently studied. The $CO_2$ permeance and $CO_2/N_2$ selectivity through the PDMS-PVP composite membrane reached 140.6 GPU and 12.0, respectively.

• Economic and Environmental Geology
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• v.36 no.6
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• pp.469-480
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• 2003

Laboratory leaching experiment study carried out to estimate a extent of heavy metals that could be leached out when acid rain(pH 5.0-3.0) and strong acidic solution(pH 2.5-1.0) reacted with tailings and contaminated soils from abandoned metal mines. In slightly to moderately acid conditions(pH 5.0-3.0), As, Pb and Zn dissolutions became significantly increased with decreased pH in tailing, while dissolution of these elements was very limited in contaminated soil. These results suggested that moderately acid rainwater leaches Pb, As and Zn from the tailings, while these elements would remain fixed in contaminated soil. In the pH range of 2.5-1.0(strongly acid condition), Zn, Cd and Cu concentrations of leachate rapidly increased with decreased pH in contaminated soil, while Pb, As and Co dissolutions became importantly increased in tailings. The experimental solubility of Zn. Cd and Cu was very low even at very low pH values(up to pH 1), except for CY4(Cheongyang mine). These can result from an incomplete dissolution or the presence of less soluble mineral phases. So, the solubility of heavy metals depends not only on the pH values of leachate but also on the speciation of metals associated with contaminated soils and tailings. The relative mobility of each element within failings at the pH 5.0-3.0 of the reaction solution was in the order of Pb>Zn>Cd>Co=Cu>As. In case of pH 2.5-1.0 of the reaction solution, the relative mobility of each element within contaminated soils and tailings were in the order of Zn＞Cd>Cu>Co>Pb=As for contaminated soils, and Pb>Zn>Cd>hs>Co>Cu for tailings. The obtained results could be useful for assessing the environmental effects and setting up the restoration plan in the areas.

• Clean Technology
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• v.24 no.1
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• pp.50-54
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• 2018

In this work, N-methyl-2-pyrrolidone (NMP) was added into diethylenetriamine (DETA) aqueous solution for high $CO_2$ loading via phase splitting of absorbents during $CO_2$ absorption. Immiscible two phases were formed in the range of more than 30 wt% of NMP in 2 M DETA + NMP + water absorbents because of low solubility of DETA-carbamate in NMP solution. As the composition of NMP in the absorbents increased, the difference of $CO_2$ loading between each phase increased and the volume of bottom phase decreased. In $CO_2$ absorption in packed column by 2 M DETA + NMP + water absorbents, the absorption rate decreased in the range of more than 40 wt% of NMP. It is due to the increasing of mass transfer resistance in liquid film of absorbents at the high concentration of NMP. DETA + NMP + water absorbent is expected as the promising one for reducing the regeneration energy of absorbents according to volume reduction of $CO_2-rich$ phase.

• Journal of the Korean Society for Marine Environment & Energy
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• v.8 no.1
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• pp.39-45
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• 2005

In the situation which Russia's ratification of the Kyoto protocol at February,2004, ANNEX I nations must reduce GHG(Green House Gas) discharge rate from 2008 by 2012 to the reduction level at 1990. We introduce the CO₂ ocean sequestration that is one of promising method for getting the stable CO₂ concentration in the atmosphere. There are four categories : ocean transportation technique, ocean initial dissolution technique, ocean deep current evaluation technique, and ocean biological evaluation technique. In this paper, we carried out the fundamental numerical study on the ocean initial dissolution technique, when the Liquidized CO₂ is emitted at the deep ocean, It is very important to the dissolution rate of movable CO₂ interface because it Is directly impact to the ocean organism. In order to investigate the relation of the interface movement and rate of the dissolution, we develope CR(Computational Fluid Dynamics) code that was constructed by the finite volume method based on the unstructured mesh, and a droplet's boundary surface can move and one direction dissolution from disperse phase into continuous phase adopted as its physics be. This study clarifies hydrodynamic relation between solubility and movement of the droplet through the verification of the Cm code.

• Clean Technology
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• v.10 no.4
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• pp.221-228
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• 2004

Ethoxylated Nonyl Phenol Series (NP-series), nonionic surfactants, were applied for forming microemulsions in supercritical $CO_2$. Measurement results of the solubility in supercritical $CO_2$ are in the following; NP-series were high soluble in carbon dioxide in spite of the fact that those were not $CO_2$-philic surfactants traditionally well known. Water in $CO_2$ microemulsions were also formed stably. A complexation of hydrophilic lengths for $CO_2$-philic parts of NP-Series surfactants was optimized by NP-4 surfactant(N=4) for forming the microemulsions through the experiments. Formation of microemulsions was confirmed by measuring the UV-Visible spectrum through a spectroscopic method and existence of water in the microemulsions was confirmed as well. In order to apply it for a metal surface treatment or electroplating, an experiment for forming acid(organic, inorganic) solution in $CO_2$ microemulsions was carried out. Ionic surfactant in the reaction to an acid solution became unstable to form microemulsions, however, nonionic surfactant was formed stably in the reaction. Results of the study will be utilized for expanding the application scope of supercritical $CO_2$ which is an environmental-friendly solvent.

• Membrane Journal
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• v.34 no.3
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• pp.192-203
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• 2024

The advancement of commercially viable gas separation membranes plays a pivotal role in improving CO₂ separation efficiency. High-molecular-weight poly(ethylene oxide) (high-Mw PEO) emerges as a promising option due to its high CO₂ solubility, affordability, and robust mechanical attributes. However, the crystalline nature of high-Mw PEO hinders its application in gas separation membranes. This study proposes a straightforward blending approach by incorporating various polymeric additives into high-Mw PEO to address this challenge. Four commercially available, water-soluble polymers, i.e. poly(ethylene glycol) (PEG), poly(propylene glycol) (PPG), poly(acrylic acid) (PAA), and poly(vinyl pyrrolidone) (PVP) are examined as additives to enhance membrane performance by improving miscibility and reducing PEO crystallinity. Contrary to expectations, PEG and PPG fail to inhibit the crystalline structure of PEO and result in membrane flaws. Conversely, PAA and PVP demonstrate greater success in altering the crystal structure of PEO, yielding defect-free membranes. A thorough investigation delves into the correlation between changes in the crystalline structure of high-Mw PEO blend membranes and their gas separation performance. Drawing from our findings and previously documented outcomes, we offer insights into designing and selecting additive polymers for high-Mw PEO, aiming at the creation of cost-effective, commercially viable CO₂ separation membranes.

• Ocean Science Journal
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• v.40 no.2
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• pp.61-66
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• 2005

Benthic amphipod, Grandidierella japonica widely inhabits the Korean coastal waters and is developed as a standard test species for sediment toxicity tests. We exposed G. japonica to various pollutants including 4 kinds of inorganic metals (Ag, Cd, Cu and Hg), tributyltin [TBT], ammonia and 7 polycyclic aromatic hydrocarbon (PAH) compounds (acenaphthene, chrysene, fluoranthene, fluorene, naphthalene, phenanthrene and pyrene) to estimate the no observed effect concentration (NOEC) and the median lethal concentration (LC50) of each pollutant during the 96-hour acute exposure. Among all tested pollutants, TBT was most toxic to G. japonica, and Rg was most toxic among inorganic metals. The toxicity of pyrene to G. japonica was greatest among PAH compounds, followed by fluoranthene, phenanathrene, acenaphthene, fluorene and naphthalene. The toxicity of PAH compounds was closely related to their physico-chemical characteristics such as $K_ow$ and water solubility. G. japonica responded adequately to pollutant concentrations and exposure durations, and the sensitivity of G. japonica to various inorganic and organic pollutants was generally comparable to other amphipods used as standard test species in ecotoxicological studies, indicating this species can be applied in the assessment of environments polluted by various harmful substances.

• Journal of the Semiconductor & Display Technology
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• v.4 no.4 s.13
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• pp.19-26
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• 2005

The process optimization of ozone concentration and half life time was investigated in ultra pure water and alkaline solutions for the wet cleaning of silicon wafer surface at room temperature. In the ultra pure water,. the maximum concentration (35 ppm) of ozone was measured at oxygen flow rate of 3 liters/min and ozone generator power over 60%. The half life time of ozone increased at lower power of ozone generator. Additive gases such as $N_2$ and $CO_2$ were added to increase the concentration and half life time of ozone. Although the maximum ozone concentration was higher with the addition of $N_2$ gas, a longer half life time was observed with the addition of $CO_2$. When $NH_4OH$ of 0.05 or 0.10 vol% was added in DI water, the pH of the solution was around 10. The addition of ozone resulted in the half life time less than 1 min. In order to maintain high pH and ozone concentration, ozone was continuously supplied in 0.05 vol% ammonia solutions. 3 ppm of ozone was dissolved in ammonia solutions. The static contact angle of silicon wafer surface became hydrophilic. The particle removal was possible alkaline ozone solutions. The organic contamination can be removed by ozonated ultra pure water and then alkaline solution containing ozone can remove the particles on silicon surface at room temperature.

• Journal of the Korean Society of Industry Convergence
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• v.6 no.3
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• pp.171-176
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• 2003

The poly(triazine bissulfide) synthesized from 6-dibutylamino-1,3,5-triazine-2,4-dithiol with bis(4-chloro-3-nitrophenyl) sulfone in the presence of the phase transfer catalyst, the maximum algebra viscosity (0.57 dL/g) is stable at reaction temperature of $60^{\circ}C$ overall. We could not acquire the good result about solubility, thermal property, and molecular weight to make cast film, we made base for the synthesis of functionalization polymer material.