• Resources Recycling
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• v.15 no.5 s.73
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• pp.17-25
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• 2006

Al-MCM-48 was used as a catalyst to decompose high density polyethylene(HDPE). Catalytic activity of Al-MCM-48 was compared with those of Al-MCM-41, Beta, and ZSM-5. Catalytic decomposition rate over Al-MCM-48 was much higher than at of non-catalytic pyrolysis only. Compared to other catalysts, Al-MCM-48 revealed the little higher activation energy value. The progressive deactivation behavior of the catalysts has also studied. ZSM-5 and Al-MCM-48 showed slower deactivation rates than Al-MCM-41 and Beta. Pyrolysis coupled with gas chromatographic separation and flame ionization detection (Py-GC/ FID) was also performed to assess the characteristics of pyrolysis products. ZSM-5 gave a higher fraction of gaseous products ($C_1-C_4$). Al-MCM-41 and Beta produced mainly $C_5-C_{12}$ products. The selectivity to oil product ($C_5-C_{22}$) obtained with Al- MCM-48 is higher an that with the other catalysts employed in this study.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.687-692
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• 1997

During the hydrogenation of rapeseed oil, reaction kinetics and physicochemical characteristics with catalysts (UP9900, DM3, Nysosel 222) were determined. Hydrogenation reaction rates for the UP 9900, Nysel DM3 and Nysosel 222 were $1.6{\pm}0.1\;({\times}10^{-2}),\;1.2{\pm}0.1\;(10^{-2}),\;1.2{\pm}0.1\;(10^{-2})$, respectively. The selectivities for the linoleic acid and oleic acid were determined to be $0.9{\sim}1.5\;and\;39{\sim}44$ at 20 min. From these results, the use of catalysts was shown to be non-selective. Trans isomer content in Nysosel 222 was 32% when the reduction rate of iodine value was 38%, that in Nysel DM3 was 28% at the reduction rate of 45%. UP9900 showed no influence on the trans isomer content. Below the melting point of $35^{\circ}C$, oleic acid and trans isomer acid were increased. On the other side, over the melting point of $35^{\circ}C$, oleic acid was decreased and trans isomer acid was constant. And this tendency was also appeared at the reduction rate of iodine value of 38%.

• Journal of Korean Society of Environmental Engineers
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• v.38 no.6
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• pp.291-298
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• 2016

Electrochemical water treatment process as a useful treatment method for the removal of non-degradable matter has been consistently studied for several decades. Key process of electrochemical water treatment are oxidation reaction from an anode and reduction from a cathode. In this study, the effect of pre-treatment methods in the insoluble electrode manufacturing process for the water treatment has been evaluated for the life time of electrode The results of this study showed that pre-treatment methods of a base metal such as surface roughness, clean method and interlayer formation influenced to life time of electrode when the same condition (catalyst electrode layer coating method and material system) was applied for pre-treatment methods. This study was conducted by using $IrO_2/Ti$ electrode In the test of sand-blasting process, an electrode manufactured by using sanding media of different sizes resulted in the most effective electrode life time when the size of alumina was used for $212{\sim}180{\mu}m$ praticle size (#80). The most effective method was considered using arc plasma in the additional roughness control and cleaning process, sputtering method to form Ta type interlayer formation process.

• Polymer(Korea)
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• v.29 no.5
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• pp.457-462
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• 2005

Polyurethane foams (PUFs) were prepared from polymeric 4,4'-diphenylmethane diisocyanate (PMDI), mixed polyol with OH value of 480, silicone surfactant, three catalysts, and hydrofluorocarbon(HFC) as blowing agent. Balance (PC-8), gelling (33LV), and trimerization (TMR-2) catalysts were used. The effect of the catalysts on the physical properties of PUF with increase of isocyanate (NCO) index and aging time was investigated. The cell size of the PUF with PC-8 and 33LV slightly increased with an increase in NCO index from 100 to 170 but compressive strength did not change significantly. In case of trimerization catalyst, the compressive strength of PUF increased from 8.75 to 1$10.5 kg_f/cm^2$ and the cell size decreased with an increase in NCO index. The compressive strength of the PUF with 33LV increased from 9.21 to $10.15 kg_f/cm^2$ with an increase in aging time. However, there was no detectable change in the compressive strength of PUF with TMR-2. A possible interpretation of the results includes an additional cross-link reaction of non-reacted MDI and FTIR spectrum illustrated the change of NCO peak.

• Applied Chemistry for Engineering
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• v.9 no.5
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• pp.704-709
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• 1998

Non-linear optical polymer based on poly (${\alpha}$-methylstyrene-co-maleic anhydride) (MSMA) substrate polymer was prepared by polymer reaction method and its thermal and electro-optic properties were examined. In the polymer reaction between MSMA substrate polymer and 2-[4-(4-nitrophenylazo)-N-ethylphenylamino]ethanol (DR1) chromophore, the degree of substitution of DR1 into MSMA was higher with the 4-dimethylaminopyridine (DMAP) as catalyst and 3-dicyclohexyl carbodiimide (DCC) as dehydrating agent (sample, MSMA-DC) than the one with just 4-dimethylaminopyridine as catalyst (sample, MSMA-D). The synthesized NLO polymer (MSMA-DC) exhibited electro-optic coefficient of 18 pm/V (632.8 nm) and glass transition temperature ($T_g$) of about $175^{\circ}C$.

• Journal of the Korean Electrochemical Society
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• v.24 no.4
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• pp.106-112
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• 2021

Catalyst poisoning by ionomers in membrane electrode assemblies of alkaline membrane fuel cells has been reported recently. We tried to improve the membrane electrode assembly's performance by controlling the solvent's ratio during electrode manufacturing. 4 Different mixing ratios of N-Methyl-2-pyrrolidone (NMP) and ethylene glycol (EG) gave four different cathode electrodes with platinum and Fuma-Tech ionomers. The electrode with higher EG improved polarization performance by about 36% compared to the NMP-based commercial ionomer. The dependence of the ionomer's dispersibility on the solvent seems responsible for the difference, which means that the non-uniform distribution of ionomers improves the performance of the electrode. High-frequency resistance, internal resistance corrected polarization curve, Tafel slope, mass activity, and impedance spectroscopy characterized the electrode. We can find that the existence of poor solvent improves cathode electrode performance. It seems to be the result of reduced poisoning of the catalyst according to the particle size distribution of the ionomer.

• Journal of the Korean Society of Earth Science Education
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• v.16 no.2
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• pp.234-246
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• 2023

This study uses Gagne's 'Differentiated Model of Giftedness and Talent (DMGT)' to collect and extract major life events of Jang Young-sil, and to investigate how giftedness was formed and developed in his life history, and what factors enabled him to demonstrate his talent in the field of science and technology. In addition, based on the framework of Gagne's Differentiation Model for Giftedness and Talent(DMGT), we analyzed the mechanism of giftedness manifestation of Jang Young-sil and sought to explore the direction of gifted education based on this. To sum up the results of the study, first, in Giftedness(G), it was found that Jang Young-sil had excellent scientific and technological skills. Second, motivation, determination, self-management, and personality factors that constitute the inner catalyst(IC) of the individual have had an impact on the development of giftedness. Third, it influenced the social environment and peer giftedness in environmental catalysis(EC). Fourth, the catalyst of chance or chance(C) was the factor that had the greatest influence on Jang Young-sil's manifestation of giftedness. Fifth, informal learning and non-institutional formal learning in the developmental process(LP) influenced the manifestation of giftedness. In this way, the talent development factors of people such as Jang Young-sil provide implications for the need to understand the manifestation mechanism of giftedness in the future, develop examination tools that can detect giftedness, and develop customized programs that can develop giftedness.

• Economic and Environmental Geology
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• v.52 no.6
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• pp.627-635
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• 2019

Cement-asbestos slate is the main asbestos containing material. It is a product made by combining 10~20% of asbestos and cement components. Man- and weathering-induced degradation of the cement-asbestos slates makes them a source of dispersion of asbestos fibres and represents a priority cause of concern. When the asbestos enters the human body, it causes cellular damage or deformation, and is not discharged well in vitro, and has been proven to cause diseases such as lung cancer, asbestos, malignant mesothelioma and pleural thickening. The International Agency for Research on Cancer (IARC) has designated asbestos as a group 1 carcinogen. Currently, most of these slats are disposed in a designated landfill, but the landfill capacity is approaching its limit, and there is a potential risk of exposure to the external environment even if it is land-filled. Therefore, this study aimed to exam the possibility of detoxification of asbestos-containing slate by using exothermic reaction and heat treatment. Cement-asbestos slate from the asbestos removal site was used for this experiment. Exothermic catalysts such as calcium chloride(CaCl₂), magnesium chloride(MgCl₂), sodium hydroxide(NaOH), sodium silicate(Na₂SiO₃), kaolin[Al₂Si₂O₅(OH)₄)], and talc[Mg₃Si₄O₁₀(OH)₂] were used. Six catalysts were applied to the cement-asbestos slate, respectively and then analyzed using TG-DTA. Based on the TG-DTA results, the heat treatment temperature for cement-asbestos slate transformation was determined at 750℃. XRD, SEM-EDS and TEM-EDS analyses were performed on the samples after the six catalysts applied to the slate and heat-treated at 750℃ for 2 hours. It was confirmed that chrysotile[Mg₃Si₂O₅(OH₅)] in the cement-asbestos slate was transformed into forsterite (Mg₂SiO₄) by catalysts and heat treatment. In addition, the change in the shape of minerals was observed by applying a physical force to the slate and the heat treated slate after coating catalysts. As a result, the chrysotile in the cement-asbestos slate maintained fibrous form, but the cement-asbestos slate after heat treatment of applying catalyst was broken into non-fibrous form. Therefore, this study shows the possibility to safely verify the complete transformation of asbestos minerals in this catalyst- and temperature-induced process.

• The Journal of Natural Sciences
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• v.17 no.1
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• pp.13-29
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• 2006

Most redox-active proteins have thiol-bearing cysteine residues that are sensitive to oxidation. Cysteine thiols oxidized to sulfenic acid are generally unstable, either forming a disulfide with a nearby thiol or being further oxidized to a stable sulfinic acid, which have been viewed as an irreversible protein modification. However, recent studies showed that cysteine residues of certain thiol peroxidases (Prxs) undergo reversible oxidation to sulfinic acid and the reduction reaction is catalyzed by sulfiredoxin (Srx1). Specific Cys residues of various other proteins are also oxidized to sulfinic acid ($Cys-So_2H$). Srxl is considered one of the oxidant proteins with a role in signaling through catalytic reduction of oxidative modification like in the reduction of glutathionylation, a post-translational, oxidative modification that occurs on numerous proteins. In this study, the role of sulfiredoxin in cellular processes, was investigated by studying its interaction with other proteins. Through the yeast two-hybrid system (Y2HS) technique, we have found that Ams1 is a potential and novel interacting protein partner of Srxl. $\alpha$-mannosidase (Ams1) is a resident vacuolar hydrolase which aids in recycling macromolecular components of the cell through hydrolysis of terminal, non-reducing $\alpha$-D-mannose residues. It forms an oligomer in the cytoplasm and under nutrient rich condition and is delivered to the vacuole by the Cytoplasm to Vacuole (Cvt) pathway. Aside from the role of Srxl as a catalyst in the reduction of cysteine sulfenic acid groups, it may play a completely new function in the cellular process as indicated by its interaction with Ams1 of the yeast Saccharomyces cerevisiae.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1215-1220
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• 2004

Reactive distillation (RD) is a combination process where both separation and reaction are considered simultaneously in a single vessel. This kind of combination to enhance the overall performance is not a new attempt in the chemical engineering areas. The recovery of ammonia in the classic Solvay process for soda ash of the 1860s may be cited as probably the first commercial application of RD. The RD system has been used for a long time as a useful process and recently the importance of the RD is enlarged more and more. In addition to that, the application fields of RD are diversely diverged. To make the most of the characteristic of RD system, we must decide the best operating condition under which the process shows the most effective productivity and should decide the best control algorithm which satisfies an optimal operating condition. Phosgene which is a highly reactive chemical is used for the production of isocyanates and polycarbonates. Because it has high reactivity and toxicity, its utilization is increasingly burdened by growing safety measures to be adopted during its production. Dimethyl Carbonate (DMC) was proposed as a substitute of phosgene because it is non-toxic and environmentally benign chemical. In this study, RD is used for DMC production process and the transesterification is performed inside of column to produce DMC. In transesterification, the methanol and ethylene carbonate (EC) are used as the reactants. This process use homogeneous catalyst and the azeotrope exists between the reactant and product. Owing to azeotrope, we should use two distillation columns. For this DMC production process, we can suggest two configurations. One is EC excess process and the other is methanol excess process. From the comparison of steady state simulation results where the Naphtali-Sandholm algorithm is used, it showed the better performance to use the methanol excess process configuration than EC excess process. Then, the dynamic simulation was performed to be based on the steady state simulation results and the optimal control system was designed. In addition to that, the optimal operating condition was suggested from previous results.