• Clean Technology
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• v.20 no.1
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• pp.64-71
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• 2014

We have investigated the effects of various additives on Eco coal gasification under $CO_2$ atmosphere. The temperature ranges from $750{\sim}900^{\circ}C$ and the gasification experimental was carried out with Eco coal adding 7 wt% $K_2CO_3$, $Na_2CO_3$, $CaCO_3$, Dolomite, and non-additive under $N_2$ and $CO_2$ gas mixture. At $850^{\circ}C$, we observed that the reaction rate increased when the concentration of $CO_2$ increased. However, we also observed that the increment of reaction rate was small at more than 70% of the concentration of $CO_2$. The additives activity was ranked as 7 wt% $Na_2CO_3$ > 7 wt% $K_2CO_3$ > non-additive > 7 wt% Dolomite > 7 wt% $CaCO_3$ at $850^{\circ}C$. At the temperatures of $750^{\circ}C$, $800^{\circ}C$, $850^{\circ}C$, and $900^{\circ}C$, when the temperature increased, the gasification rate increased. The gasification was suitably described by the volumetric reaction model. Using volumetric reaction model, the activation energy of Eco coal including 7 wt% $Na_2CO_3$ gasification was 83 kJ/mol, which was the lowest value among all the alkaline additives.

• Resources Recycling
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• v.5 no.3
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• pp.65-72
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• 1996

Colloidal calcium wrbonate(diametcr 0.02-0 09 m~wja s developed to maintain the mamenl of pnriide formatio~>w ~lhoutsurlace trealment. The control factors of particle size and optimum condiliuna for compound fam*tition has not bccn studiedyet. This shldy war aimed at developing a method fur compounding colloidal calcium carbonfcte to cnl~hol cubic calciumcarbonate, and then compounding the b-o types oI precipitated calcium wrbonatc under optimum wndilrans Calc~umhydroxide was calcinated at 1, lWC far two hours, md then hydrated for 30 minutes at t i i O rprn and ambiznt temperahlle.Two-liter suspension was subjected to the contact with carbon dioxide at l5"C, 600 ipxn and C0= injection in the rate of 1 Umin Two types of dcium carbonate(cuhic calcium carbonatc(0 24.9 pm) md collnidd calcium mhnnate (0.02-0 09 pm))were compounded by "wing the concentrations of calcium oxide and ihe suspension were compounded. It was found that theoptimum concentrations of each suspensions were 5 wt % and 2.5 \I*.% respectively. ' h c key control factor af thc parlicle slzcdislribution was the concenkation al the suspension. The size of compounded particles was measured by a Zcla S k r 'fieaverage particle size of the cubic calcium carbonate aas 223.4 nm(0.223 pm), and that of thc colloidal a~lciumc arbonate was93.6 nm (0.093 km). Ihe particle sizc was evenly cantlolled on a stdblc basis in an H, O reaction system.asis in an H, O reaction system.

• Applied Biological Chemistry
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• v.39 no.3
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• pp.245-248
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• 1996

Thermal stability of the major color component, cyanidin 3-glucoside, isolated from Korean pigmented rice (Oryza sativa var. Suwon 415) were investigated to explore possible application of value-added natural colors as food additives. The anthocyanin showed red and blue color with maximum absorption peaks at 511 nm and 572 nm in acidic (pH 2.0) and alkaline (pH 9.0) buffer solutions, respectively, and the thermal degradation reactions were carried out with different temperature ranges at $50{\sim}95^{\circ}C$. Degree of degradation was determined with UV/Vis spectra which indicate characteristic absorption patterns with sharp isosbestic points at 350 nm (pH 2.0), and 275, 310, and 405 nm (pH 9.0). Thus the reaction follows simple first-order kinetics. The anthocyanin was very stable against heat at acidic pH and relatively stable at alkaline pH with half-life values of 50.3 hr and 0.6 hr at $70^{\circ}C$, respectively. The activation energies and Arrhenius frequency factors of the pigment were 26.9 kcal $mol^{-1}\;and\;6.0{\times}10^{11}\;s^{-1}$, at pH 2.0, and 15.2 kcal $mol^{-1}\;and\;1.4{\times}10^{6}\;s^{-1}$, pH 9.0, and respectively.

• Applied Chemistry for Engineering
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• v.33 no.2
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• pp.151-158
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• 2022

In this paper, parameter characteristics such as pH effect, isotherm, kinetic and thermodynamic parameters and competitive adsorption of dyes including malachite green (MG), direct red 81 (DR 81) and thioflavin S (TS), which have different functional groups, being adsorbed onto activated carbon were investigated. Langmuir, Freundlich and Temkin isotherm models were employed to find the adsorption mechanism. Effectiveness of adsorption treatment of three dyes by activated carbon were confirmed by the Langmuir dimensionless separation factor. The mechanism was found to be a physical adsorption which can be verified through the adsorption heat calculated by Temkin equation. The adsorption kinetics followed the pseudo second order and the rate limiting step was intra-particle diffusion. The positive enthalpy and entropy changes showed an endothermic reaction and increased disorder via adsorption at the S-L interface, respectively. For each dye molecule, negative Gibbs free energy increased with the temperature, which means that the process is spontaneous. In the binary component system, it was found that the same functional groups of the dye could interfere with the mutual adsorption, and different functional groups did not significantly affect the adsorption. In the ternary component system, the adsorption for MG lowered a bit, likely to be disturbed by the other dyes meanwhile DR 81 and TS were to be positively affected by the presence of MG, thus resulting in much higher adsorption.

• Korean Chemical Engineering Research
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• v.52 no.5
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• pp.657-666
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• 2014

Coal gasification technology is considered as next generation clean coal technology even though it uses coal as fuel which releases huge amount of greenhouse gas because it has many advantages for carbon capture. Coal or pet-coke slurry gasification is very attractive technology at present and in the future because of its low construction cost and flexibility of slurry feeding system in spite of lower efficiency compared to dry feeding technology. In this study, we carried out gasification experiment using bituminous coal slurry sample by integrating coal slurry feeding facility and slurry burner into existing dry feeding compact gasifier. Especially, our experiment was conducted under fairly lower operation temperature than that of existing entrained-bed gasifier, resulting in partial slagging operation mode in which only part of ash was converted to slag and the rest of ash was released as fly ash. Carbon conversion rate was calculated from data analysis of collected slag and ash, and then cold gas efficiency, which is the most important indicator of gasifier performance, was estimated by carbon mass balance method. Fairly high performance considering pilot-scale experiment, 98.5% of carbon conversion and 60.4% of cold gas efficiency, was achieved. In addition, soundness of experimental result was verified from the comparison with chemical equilibrium composition and energy balance calculations.

• Journal of Life Science
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• v.25 no.10
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• pp.1148-1155
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• 2015

Commercial complete feeds contain enough nutrients to support animal growth and it is easy to be spoiled under proper temperature and humid conditions. The aim of this study was to investigate microbiological and chemical changes on complete feed for milking cow under open-air exposure with moisture 33% at 30℃ during 15 days. pH decreased 6.29 to 4.66 and water activity decreased gradually 0.99 to 0.95. Bacteria increased 6.2×10⁶~1.6×10⁷ to 2.1×10⁹ CFU/g at 5 days and showed 10⁸ CFU/g until 15 days. Fungi increased 10³ CFU/g to 8.0×10⁴ CFU/g. During the processing of spoilage, bacteria such as Acinetobacter oleivorans, Pediococcus acidilactici, Acinetobacter oleivorans, Weissella cibaria, and Methylobacterium komagatae were identified and fungi such as Fusarium sp. and Mucor sp. were also identified. Moisture content increased until 10 days (p<0.01). Crude protein was not changed so much whereas crude fat decreased 6.0% to 5.5% (p<0.01). Crude fiber and crude ash changed 2.0~ 3.0% and 4.5~ 4.8% levels with no significance, respectively. Gross energy was not almost changed at 4,400 kcal/g. During spoilage, lactate and propionate increased whereas acetate was not detected. Protease and lipase activities increased significantly during spoilage (p<0.01). Zearalenone content increased 59.2 μg/kg to 623.8 μg/kg, showing 10.5 times more production. During feed spoilage, pH decreased with microbial growth and various chemical changes were occurred.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.5
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• pp.383-391
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• 1992

A comparative study of enzymatic properties between the trypsin from the cat-shark Cephaloscyllium umbratile ( C-T) and the two trypsins from the mackerel Scomber japonicus $(M-T_A\;and\;M-T_B)$ was carried out following after the previous paper(Pyeun et al., 1991). Trypsin from cat-shark(C-T) showed the higher heat stability compared to the others $(M-T_A\;and\;M-T_B)$ and its denaturation constant$(K_D)$ was $10.68\times10^{-4}\;sec^{-1}\;at\;55^{\circ}C$ with BA-p-NA substrate. The activation energies(Ea) of the trypsins measured at a temperature range from $30^{\circ}C\;to\;50^{\circ}C$ were estimated to be 4.07 kcal/mole for C-T, 11.61 kcal/mole for $M-T_A$, and 8.43kcal/mole for $M-T_B$, respectively. The Km values were $24.9\times10^{-5}\;M\;for\;C-T,\;5.37\times10^{-5}\;M\;for\;M-T_A,\;and\;9.65\times10^{-5}\;M\;for\;M-T_B$. On the other hand, the Ki values for TLCK and DFP determined by Dixon plot were $1.50\times10^{-6}\;M\;and\;9.28\times10^{-6}\;M\;for\;C-T\;2.86\times10^{-6}\;M\;and\;2.11\times10^{-4}\;M\;for\;M-T_A\;and\;3.90\times10^{-6}\;M\;and\;1.60\times10^{-4}\;M\;for\;M-T_B$ Similar amino acid profiles were showed between three trypsins each other, with few exceptions of $M-T_B$ containing higher amount of arginine, and the smaller amount of tryptophan in C-T than the others.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.1
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• pp.68-77
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• 2022

The human thermal environment in an apartment complex located in Seoul was quantitatively analyzed to devise methods to modify human heat-related stresses in landscape and urban planning. Microclimatic data (air temperature, relative humidity, wind speed, and short- and long-wave radiation) were collected at 6 locations [Apt-center, roof (cement), roof (grass), ground, playground, and a tree-lined road] in the late spring and summer, and the data were used to estimate the human thermal sensation, physiological equivalent temperature (PET) and universal thermal climate index (UTCI). As a result, the playground location had the highest thermal environment, and the roof (grass) location had the lowest. The mean difference between the two locations was 0.8-1.1℃ in air temperature, 1.8-4.0% in relative humidity, and 7.5-8.0℃ in mean radiant temperature. In open space locations, the wind speed was 0.4-0.5 ms-1 higher than others. Also, a wind tunnel effect happened at the Apt-center location during the afternoon. For the human thermal sensation, PET and UTCI, the mean differences between the playground and roof (grass) locations were: 5.2℃ (Max. 11.7℃) in late spring and 5.4℃ (Max. 18.1℃) in summer in PET; and 3.0℃ (Max. 6.1℃) in late spring and 2.6℃ (Max. 9.8℃) in summer in UTCI. The mean differences indicated a level change in PET and 1/2 level in UTCI, and the maximum differences showed greater changes, 2-3 levels in PET, and 1-1.5 levels in UTCI. Moreover, the roof (grass) location gave 4.6℃ PET reduction and a 2.5℃ UTCI reduction in late spring, and a 4.4℃ PET reduction and a 2.0℃ UTCI reduction in the summer when compared with the roof (cement) location, which results in a 2/3 level change in PET and a 1/3 level in UTCI. Green infrastructure locations [roof (grass), ground, and a tree-lined road] were not statistically significant in the reduction of PET and UTCI in thermal environment modifying effects. The implementation of green infrastructure, such as rooftop gardens, grass pavement, and street tree planting, should be adopted in landscape planning and be employed for human thermal environment modification.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.2
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• pp.101-112
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• 2016

This study investigated the removal of Sr, which was one of the high radioactive nuclides, by adsorption with Barium (Ba) impregnated 4A zeolite (BaA) from high-radioactive seawater waste (HSW). Adsorption of Sr by BaA (BaA-Sr), in the impregnated Ba concentration of above 20.2wt%, was decreased by increasing the impregnated Ba concentration, and the impregnated Ba concentration was suitable at 20.2wt%. The BaA-Sr adsorption was added to the co-precipitation of Sr with $BaSO_4$ precipitation in the adsorption of Sr by 4A (4A-Sr) within BaA. Thus, it was possible to remove Sr more than 99% at m/V (adsorbent weight/solution volume)=5 g/L for BaA and m/V >20 g/L for 4A, respectively, in the Sr concentration of less than 0.2 mg/L (actual concentration level of Sr in HSW). It shows that BaA-Sr adsorption is better than 4A-Sr adsorption in for the removal capacity of Sr per unit gram of adsorbent, and the reduction of the secondary solid waste generation (spent adsorbent etc.). Also, BaA-Sr adsorption was more excellent removal capacity of Sr in the seawater waste than distilled water. Therefore, it seems to be effective for the direct removal of Sr from HSW. On the other hand, the adsorption of Cs by BaA (BaA-Cs) was mainly performed by 4A within BaA. Accordingly, it seems to be little effect of impregnated Ba into BaA. Meanwhile, BaA-Sr adsorption kinetics could be expressed the pseudo-second order rate equation. By increasing the initial Sr concentrations and the ratios of V/m, the adsorption rate constants ($k_2$) were decreased, but the equilibrium adsorption capacities ($q_e$) were increasing. However, with increasing the temperature of solution, $k_2$ was conversely increased, and $q_e$ was decreased. The activation energy of BaA-Sr adsorption was 38 kJ/mol. Thus, the chemical adsorption seems to be dominant rather than physical adsorption, although it is not a chemisorption with strong bonding form.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.1
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• pp.85-92
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• 2005

The performance of a novel fermentation process, adopting a sludge blanket type configuration for higher hydrolysis/acidogenesis of the municipal primary sludge, was investigated under batch and semi-continuous conditions with various pH and temperature conditions. This acid elutriation slurry reactor provided higher system performance with a short HRT (5 days) and higher acidogenic effluent quality under pH 9 and thermophilic ($55^{\circ}C$) conditions. The hydrolysis of the sludge was revealed to be significantly dependent on seasonal effects for sludge characteristics but with little impact on acidogenesis. Based on the rainy season at the optimum conditions, VFA production and recovery fraction ($VFA_{COD}/COD$) were $0.18\;g\;VFA_{COD}\;g^{-1}\;VSS_{COD}$ and 63%. As byproducts, nitrogen and phosphorus releasing were $0.006\;g\;N\;g^{-1}\;VSS_{COD}$ and $0.003\;g\;P\;g^{-1}\;VSS_{COD}$, respectively. For the mass balance in a full-scale plant($Q=158,880\;m^3\;day^{-1}$) based on the rainy season, the VFA and non-VFA(as COD) production were $3,110\;kg\;VFA_{COD}\;day^{-1}$ and $1,800\;kg\;COD\;day^{-1}$, resulting in an increase of organics of $31\;mg\;COD\;L^{-1}$ and $20\;mg\;VFA_{COD}\;L^{-1}$ and nutrients of $0.7\;mg\;N\;L^{-1}$ and $0.3\;mg\;P\;L^{-1}$ in the influent sewage. The economical benefit from this process application was estimated to be about $67 per $1,000m^3$ of sewage except for energy requirements and also, better benefits can be expected during the dry season. Also, the results revealed that the process has various additional advantages such as pathogen-free stabilized solids production, excellent solids control and economical benefits.