• Journal of Environmental Science International
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• v.28 no.1
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• pp.65-73
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• 2019

The catalytic activity of Ni-0.2%YSZ (Yttria-Stabilized Zirconia) with different promoters was evaluated for $CO_2$ methanation. The catalysts were weighed for mixing and they were dried at $110^{\circ}C$ for molding into disks. The concentration of $CO_2$ and $CH_4$ for conducting of $CO_2$ methanation were analyzed by gas chromatography and the physical characteristics of the disk-type catalyst formed were analyzed by X-ray diffraction, scanning electron microscope and energy dispersive x-ray spectrometer. The addition of $CeO_2$ as a promoter for Ni-0.2%YSZ (denoted as Ni-5%Ce-0.2%YSZ) resulted in the highest $CO_2$ methanation. It also showed catalytic activity at a low temperature($200^{\circ}C$). Following this, $ZrO_2$, $SiO_2$, $Al_2O_3$ and $TiO_2$ were added to Ni-5%Ce-0.2%YSZ to compare the $CO_2$ methanation, and the highest efficiency was found for. Ni-1%Ti-5%Ce-0.2%YSZ Then, the concentration of Ti was increased to 10% and the catalytic activity was estimated using seven different types of commercial $TiO_2$. In conclusion, ST-01 $TiO_2$ showed the highest efficiency for $CO_2$ methanation.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1275-1284
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• 2022

This study provides an investigating the electrolyte reaction characteristics during thermal runaway of a lithium-ion battery(LIB). Dimethyl carbonate(DMC) is known as the main substance that makes up the electrolyte. The mono-molecular decomposition characteristics of DMC were derived through numerical analysis. Cobalt oxide can release oxygen under high temperature conditions. Also, DMC is converted to CH₄, H₂, CO, and CO₂. Especially, it was found that the decomposition of the DMC begins at a temperature range of 340-350℃, which dramatically increases the internal pressure of the LIB. In the by-products gases, the molar ratio of CO and CO₂ changed according to the molecular structure of DMC and temperature conditions. The correlation of the [CO]/[CO₂] ratio according to the temperature during thermal runaway was derived, and the characteristics of the reaction temperature could be estimated using the molar ratio as an indicator. In addition, the oxidation and decomposition characteristics of DMC according to the residence time for each temperature were estimated. When DMC is exposed to low temperature for a long time, both oxidation and decomposition may occur. There is possibility of not only increasing the internal pressure of the LIB, but also promoting thermal runaway. In this study, internal environment of LIB was identified and the reaction characteristics between the active materials of the cathode and electrolyte were investigated.

• Clean Technology
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• v.30 no.1
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• pp.37-46
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• 2024

Environmental problems caused by plastic waste have been continuously growing around the world, and plastic waste is increasing even faster after COVID-19. In particular, PP and PE account for more than half of all plastic production, and the amount of waste from these two materials is at a serious level. As a result, researchers are searching for an alternative method to plastic recycling, and plastic pyrolysis is one such alternative. In this paper, a numerical study was conducted on the pyrolysis behavior of non-condensable gas to predict the chemical reaction behavior of the pyrolysis gas. Based on gas products estimated from preceding literature, the behavior of non-condensable gas was analyzed according to temperature and residence time. Numerical analysis showed that as the temperature and residence time increased, the production of H₂ and heavy hydrocarbons increased through the conversion of the non-condensable gas, and at the same time, the CH₄ and C₆H₆ species decreased by participating in the reaction. In addition, analysis of the production rate showed that the decomposition reaction of C₂H₄ was the dominant reaction for H₂ generation. Also, it was found that more H₂ was produced by PE with higher C₂H₄ contents. As a future work, an experiment is needed to confirm how to increase the conversion rate of H₂ and carbon in plastics through the various operating conditions derived from this study's numerical analysis results.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.8
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• pp.1111-1119
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• 2016

Mao seed is a by-product of the wine and juice industry, which could be used in animal nutrition. The current study was designed to determine the effect of supplementation of mao (Antidesma thwaitesianum Muell. Arg.) seed meal (MOSM) containing condensed tannins (CT) on rumen fermentation, nitrogen (N) utilization and microbial protein synthesis in goats. Four crossbred (Thai Native${\times}$Anglo Nubian) goats with initial body weight (BW) $20{\pm}2kg$ were randomly assigned to a $4{\times}4$ Latin square design. The four dietary treatments were MOSM supplementation at 0%, 0.8%, 1.6%, and 2.4% of total dry matter (DM) intake, respectively. During the experimental periods, all goats were fed a diet containing roughage to concentrate ratio of 60:40 at 3.0% BW/d and pangola grass hay was used as a roughage source. Results showed that supplementation with MOSM did not affect feed intake, nutrient intakes and apparent nutrient digestibility (p>0.05). In addition, ruminal pH and ammonia nitrogen ($NH_3$-N) were not influenced by MOSM supplementation, whilst blood urea nitrogen was decreased quadraticly (p<0.05) in goats supplemented with MOSM at 2.4% of total DM intake. Propionate was increased linearly with MOSM supplementation, whereas acetate and butyrate were remained the same. Moreover, estimated ruminal methane ($CH_4$) was decreased linearly (p<0.05) when goats were fed with MOSM at 1.6% and 2.4% of total DM intake. Numbers of bacteria and protozoa were similar among treatments (p>0.05). There were linear decreases in urinary N (p<0.01) and total N excretion (p<0.01) by MOSM supplementation. Furthermore, N retention was increased linearly (p<0.05) when goats were fed with MOSM supplementation at 1.6% and 2.4% of total DM intake. Microbial protein synthesis were not significantly different among treatments (p>0.05). From the current study, it can be concluded that supplementation of MOSM at 1.6% to 2.4% of total DM intake can be used to modify ruminal fermentation, especially propionate and N utilization in goats, without affecting the nutrient digestibility, microbial populations and microbial protein synthesis.

• Korean Journal of Plant Tissue Culture
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• v.27 no.3
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• pp.155-161
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• 2000

This experiment was carried out to examine the effects of culture medium on cell growth of the viola (Viola patrinii DC.) suspension culture. The results are as follows: The greatest cell growth rates were found with MS medium suggesting that this medium could be recommendable for the viola suspension cell culture. When the nitrogen sources (NH$_4$NO$_3$ and KNO$_3$) of MS salts were diluted at half concentrations, the cell growth rates were slightly increased, but when the combined concentration rations of NH$_4$+ and NO$_3$ions were 25 to 75 the greatest cell growth rates were obtained. This result imply that the nitrogen ion sources had slight influence on the rates. Another feature was obtained. This result implys that the nitrogen ion sources had slight influence on the rates. Another feature was that as the concentration of NH$_4$+ ion lowered, the callus color changed to pale yellow with some red spots. The addition of casein hydrolysate (5 g/L) was more effective for the cell growth. On the basis of microscopic observation, the highest cell growth rates were detected during 2-4 weeks culture and after 6 weeks of the culture, some elongated and vacuolated cells were determined.

• Journal of the Korean Chemical Society
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• v.42 no.6
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• pp.618-628
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• 1998

Pure CaO, Mn-doped CaO, Mn/CaO, and K/CaO catalysts were prepared and tested as catalysts for the oxidative coupling of methane in the temperature range of 600 to 800$^{\circ}C$ to investigate the effects of Mn- and K-addition on the catalytic activity of calcium oxide. To characterize the catalysts, X-ray powder diffraction(XRD), XPS, SEM, DSC, and TG analyses were performed. The catalytic reaction was carried out in a single-pass flow reactor using on-line gas chromatography system. Normalized reaction conditions were generally $p(CH_4)/p(O_2)=250$ Torr/50 Torr, total feed flow rate=30 mL/min, and 1 atm of total pressure with He being used as diluent gas. Among the catalysts tested, 6.3 mol% Mn-doped CaO catalyst showed the best $C_2$ yield of 8.0% with a selectivity of 43.2% at 775$^{\circ}C$. The $C_2$ selectivity increased on lightly doped CaO catalysts, while decreased on heavily doped CaO([Mn] > 6.3 mol%) catalysts. 6 wt.% Mn/CaO and 6 wt.% K/CaO catalysts showed the $C_2$ selectivities of 13.2% and 30.9%, respectively, for the reaction. Electrical conductivities of CaO and Mn-doped CaO were measured in the temperature range of 500 to 1000$^{\circ}C$ at Po2's of $10^{-3}\; to\;10^{-1}\;atm.$ The electrical conductivity was decreased with Mn-doping and increased with increasing $P0_2$in the range of $10^{-3}\;to\;10^{-1}\;atm,$ indicating the specimens to be p-type semiconductors. It was suggested that the interstitial oxygen ions formed near the surface can activate methane and the formation of interstitial oxygen ions was discussed on the basis of solid-state chemistry.

• Polymer(Korea)
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• v.32 no.5
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• pp.465-469
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• 2008

Hybrid thin films composed of block copolymer(BCP) and $TiO_2$ with various morphologies on the nanoscale were fabricated using self-assembly of block copolymer combined with sol-gel process. The factors governing morphology changes considered in this study are block copolymer composition, selectivity of solvent and the inclusion of an additive. We also investigated the efficiency of photoluminescence for selected films with different morphologies. Micelle or nanowire structure can be derived from the self-assembly of poly (styrene-block-4-vinyl pyridine) (PS-b-P4VP) depending on the relative selectivity of the solvent for the two blocks, and the titanium tetraisopropoxide ($Ti{OCH (CH_3)_2}_4$, TTIP) is coordinated with nitrogen in P4VP block. Addition of a third component 3-pentadecylphenol into the BCP/sol-gel mixture solution induces morphology change as a result of the change of relative volume fraction of the BCP. We confirmed that the efficiency of $TiO_2$ fluorescence changes for films depending on morphologies.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.4
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• pp.351-357
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• 1987

A laboratory experiment was conducted to find out the effect of organic fertilizer as Bio-com$^{(R)}$ on the changes of pH and Eh values, gas evolution, ammonification and nitrification, and microbial population with farmer's compost and refused mushroom compost in submerged paddy condition. The results obtained are summarized as follows: 1. Application of compost and refused mushroom compost was increased the pH values than that of NPK alone. Organic fertilizer of Bio-com$^{(R)}$ showed the same results of the farmer's compost or refused mushroom compost. 2. Population of soil microbes as bacteria, actinomycetes and fungi was increased by application of compost, refused mushroom compost and Bio-com$^{(R)}$. Moreover, the results were pronounced more with the addition of NPK. 3. The application of Bio-com$^{(R)}$ was effected to the increase of the amount of $NO_3-N$ and the rate of nitrification than NPK, farmer's compost or refused mushroom compost. 4. The amounts of evolved gases as $CH_4$, $CO_2$, and $N_2O$ were not much differed with application of kinds of compost and NPK, but little increasing tendency was observed in application of NPK than that of NPK+kinds of compost.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.1
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• pp.29-36
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• 2021

In spite of the highest energy potential among all domestic organic solid wastes. the research on biogas production from cattle manure is limited. In particular, effects of organic content degradation and sawdust addition during storage on biomethane potential have never been investigated. In the present work, we investigated the change of organic content during storage of cattle manure under different temperatures (20℃ and 30℃), and its impact on biomethane potential and odor emissions. 90 days of investigation results showed that 10% of organics in terms of VS and COD were degraded at 20℃ during storage, while 30% were degraded at 30℃. This result impacted on biomethane potential, while 10-13% and 24% reduction were observed from beef and dairy cattle manure, respectively. The temperature also affected on CH4 and odor emissions during storage by 3.3-3.8 times and 29 times. The effect of sawdust on lowering down biomethane potential was found to be substantial, reducing 61-75% compared to the control.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.479-486
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• 2023

In this study, we investigated the effect of the Ce_xZr_1-xO₂ (CZ) addition onto Ni/Al₂O₃ catalysts on the catalytic performance in methane steam reforming. In the reaction results, the CZ-added Ni/Al₂O₃ catalyst showed higher CH₄ conversion and H₂ yield under the same reaction conditions than Ni/Al₂O₃. From the characterization data, the two catalysts had similar support porosity and Ni dispersion, confirming that the two properties could not determine the catalytic performance. However, the oxygen vacancy over the CZ-added Ni/Al₂O₃ catalyst induced an efficient steam activation at low reaction temperatures, resulting in an increase in the catalytic activity and H₂ yield.