• Applied Chemistry for Engineering
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• v.25 no.4
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• pp.430-436
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• 2014

Allura Red (AR) is a water-soluble harmful tar-based food colorant (FD & C Red 40). Batch adsorption studies were performed for the removal of AR using bituminous coal based granular activated carbon as adsorbent by varying the operation parameters such as adsorbent dosage, initial concentration, contact time and temperature. Experimental equilibrium adsorption data were analyzed by Langmuir, Freundlich and Temkin isotherms. The equilibrium process was described well by Freundlich isotherm. From determined separation factor ($R_L$), adsorption of AR by granular activated carbon could be employed as effective treatment method. Temkin parameter, B was determined to 1.62~3.288 J/mol indicating a physical adsorption process. By estimation of adsorption rate experimental data, the value of intraparticle diffusion rate constant ($k_m$) increased with the increasing adsorption temperature. The adsorption process were found to confirm to the pseudo second order model with good correlation. Thermodynamic parameters like change of free energy, enthalpy, and entropy were also calculated to predict the nature adsorption in the temperature range of 298~318 K. The negative Gibbs free energy change (${\Delta}G$ = -2.16~-6.55 kJ/mol) and the positive enthalpy change (${\Delta}H$ = + 23.29 kJ/mol) indicated the spontaneous and endothermic nature of the adsorption process, respectively.

• Korean Chemical Engineering Research
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• v.57 no.5
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• pp.679-686
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• 2019

Characteristics of adsorption equilibrium, kinetic and thermodynamic of aniline blue onto activated carbon from aqueous solution were investigated as function of initial concentration, contact time and temperature. Adsorption isotherm of aniline blue was analyzed by Langmuir, Freundlich, Redlich-Peterson, Temkin and Dubinin-Radushkevich models. Langmuir isotherm model fit better with isothermal data than other isotherm models. Estmated Langmuir separation factors ($R_L=0.036{\sim}0.068$) indicated that adsorption process of aniline blue by activated carbon could be an effective treatment method. Adsorption kinetic data were fitted to pseudo first order model, pseudo second order model and intraparticle diffusion models. The kinetic results showed that the adsorption of aniline blue onto activated carbon well followed pseudo second-order model. Adsorption mechanism was evaluated in two steps, film diffusion and intraparticle diffusion, by intraparticle diffusion model. Thermodynamic parameters such as Gibbs free energy, enthalpy and entropy for adsorption process were estimated. Enthalpy change (48.49 kJ/mol) indicated that this adsorption process was physical adsorption and endothermic. Since Gibbs free energy decreased with increasing temperature, the adsorption reaction became more spontaneously with increasing temperature. The isosteric heat of adsorption indicated that there is interaction between the adsorbent and the adsorbate because the energy heterogeneity of the adsorbent surface.

• Korean Journal of Food Science and Technology
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• v.25 no.6
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• pp.794-800
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• 1993

A lipid producing yeast was screened from leaves of Albabiscus and was identified as a Rhodotorula graminis SW 214. During the shakining incubation of 8 days at $25^{\circ}C$, the yeast produced extracellular lipids of 7.3g/l of the media. The relative concentration of carbon and nitrogen sources in the media influenced the extracellular lipid production greatly. When with nitrogen sources in the media were almost exhausted for growth of the yeast the sufficient carbon sources, the lipid production proceeded vigorously. Eight days of batch cultivation with 8% glucose, 2.5g/l of yeast extract, $KH_{2}PO_{4}(1g/l)\;MgSO_{4}\;(0.2g/l)$ and pH 6 gave maximum biomass and extracellular lipid production of 8.05g/l and 8.89g/l, respectively. The acid value, saponificatio value, the iodine value, ad the unsaponifiable matter of the extracellular lipids of Rhodotorula graminis SW 214 were 2.6, 534, 5.1 and 2.4, respectively. Lipid was constituted 75.2% triglyceride, 5.9% free fatty acid, 10.8% phospholipid, 4.9% esterified sterol and 3.3% free sterol. Major fatty acids found were 3-hydroxypentadecanoate, 3-hydroxyhexadecanate, trans-9-octadecanate, cis-9-hexadecanate (hydroxy palmitic), 15-methylhexadecanate (oleic), 18-methylno-nadecanate, octadecanate (stearic) and 3-hydroxytridecante.

• Journal of Energy Engineering
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• v.24 no.4
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• pp.89-96
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• 2015

Recently, much research has been put into finding the causes and solutions of slagging/fouling problems that occur at the end of the boiler. This slagging/fouling, caused by low-rank coal's ash, disturbs the thermal power and greatly reduces efficiency. In environmental aspects, such as NOx pollution, governments have been implementing restrictions on the quantity of emission gases that can be released into the atmosphere. To solve these problems, research on Ash Free Coal (AFC), which eliminates ash from low-rank coal, is in progress. AFC has advantages over similar high-rank coals because it increases the heating value of the low grade coal, reduces the contaminants that are emitted, and decreases slagging/fouling problems. In this study, using a DTF, the changes of NOx emissions, unburned carbon, and the characteristics of ash deposition were identified. KCH raw coal, AFC extracted from KCH, residue coal, Glencore, and Mixed Coal (Glencore 85wt% and residue coal 15wt%) were studied. Results showed that AFC had a significantly lower emission of NOx compared to that of the raw coal and residue coal. Also, the residue coal showed a higher reactivity compared to raw coal. And finally, In the case of the residue coal and mixed coal, they showed a lower ash deposition than that of low-rank coal.

• Steel and Composite Structures
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• v.29 no.3
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• pp.405-422
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• 2018

In this research, experimental tensile test and manufacturing of carbon nanotube reinforced composite beam (CNTRC) is presented. Also, bending, buckling, and vibration analysis of CNTRC based on various beam theories such as Euler-Bernoulli, Timoshenko and Reddy beams are considered. At first, the experimental tensile tests are carried out for CNTRC and composite beams in order to obtain mechanical properties and then using Hamilton's principle the governing equations of motion are derived for Euler Bernoulli, Timoshenko and Reddy theories. The results have a good agreement with the obtained results by similar researches and it is shown that adding just two percent of carbon nanotubes increases dimensionless fundamental frequency and critical buckling load as well as decreases transverse deflection of composite beams. Also, the influences of different manufacturing processes such as hand layup and industrial methods using vacuum pump on composite properties are investigated. In these composite beams, glass fibers used in an epoxy matrix and for producing CNTRC, CNTs are applied as reinforcement particles. Applying two percent of CNTs leads to increase the mechanical properties and increases natural frequencies and critical buckling load and decreases deflection. The obtained natural frequencies and critical buckling load by theoretical method are higher than other methods, because there are some inevitable errors in industrial and hand layup method. Also, the minimum deflection occurs for theoretical methods, in bending analysis. In this study, Young's and shear modulli as well as density are obtained by experimental test and have not been used from the results of other researches. Then the theoretical analysis such as bending, buckling and vibration are considered by using the obtained mechanical properties of this research.

• Transactions of the Korean hydrogen and new energy society
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• v.24 no.3
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• pp.230-236
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• 2013

In this study, successive coating and co-sintering techniques have been used to fabricate LSM/GDC based cathode supported direct carbon fuel cells. The porous LSM/GDC cathode substrate, dense, thin and crack free GDC and ScSZ layers as bi-layer electrolyte, and a porous Ni/ScSZ anode layer was obtained by co-firing at $1400^{\circ}C$. The porous structure of LSM/GDC cathode substrate, after sintering at $1400^{\circ}C$, was obtained due to the presence of GDC phase, which inhibits sintering of LSM because of its higher sintering temperature. The electrochemical characterization of assembled cell was carried out with air as an oxidant and carbon particles in molten carbonate as fuel. The measured open circuit voltages (OCVs) were obtained to be more than 0.99 V, independent of testing temperature. The peak power densities were 116, 195 and $225mWcm^{-2}$ at 750, 800 and $850^{\circ}C$, respectively.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.10
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• pp.1330-1336
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• 2008

Here we studied the changes on quality characteristics of Dongchimi by supercritical carbon dioxide to manufacture Dongchimi of high quality. There were no distinctive changes of acidity, pH, color difference, free sugar and organic acid of the Dongchimi treated with supercritical $CO_2$, compared to the control. The content of vitamin C in Dongchimi, which was treated with supercritical $CO_2$ (at 25 MPa, $35^{\circ}C$) was 0.826 mg/mL, and was similar to that of 0.1 MPa. Unpleasant volatile compounds such as dimethyl disulfide, metyl trisulfide and methyl propyl disulfide in Dongchimi were decreased by supercritical $CO_2$; also, treatment of supercritical $CO_2$ was useful to improve flavor of Dongchimi. Polygalacturonase activity was decreased 40.3% after supercritical carbon dioxide treatment at 25 MPa and $55^{\circ}C$.

• Korean Chemical Engineering Research
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• v.53 no.1
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• pp.64-70
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• 2015

Batch experiment studies were carried out for adsorption of congo red using granular activated carbon with various parameters such as activated carbon dose, pH, initial dye concentration, temperature and contact time. Equilibrium experimental data are fitted to the Langmuir, Freundlich, Temkin and Dubin-Radushkevich isotherm equations. From Freundlich's separation factor (1/n) estimated, adsorption could be employed as effective treatment method for adsorption of congo red from aqueous solution. Base on Temkin constant (B) and Dubinin-Radushkevich constant (E), this adsorption process is physical adsorption. Adsorption kinetics has been tested using pseudo-first order and pseudo second order models. The results followed pseudo second order model with good correlation. Adsorption process of congo red on granular activated carbon was endothermic (${\Delta}H$=42.036 kJ/mol) and was accompanied by decrease in Gibbs free energy (${\Delta}G$=-2.414 to -4.596 kJ/mol) with increasing adsorption temperature.

• The Korean Journal of Ceramics
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• v.2 no.1
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• pp.19-24
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• 1996

The phase distribution and interface chemistry by the solid-state reaction between SiC and nickel were studied at temperatures between $550 \;and\; 1250^{\circ}C$ for 0.5-100 h. The reaction with the formation of silicides and carbon was first observed above $650^{\circ}C$. At $750^{\circ}C$, as the reaction proceeded, the initially, formed $Ni_3Si_2$ layer was converted to $Ni_2$Si. The thin nickel film reacted completely with SiC after annealing at $950^{\circ}C$ for 2 h. The thermodynamically stable $Ni_2$Si is the only obsrved silicide in the reaction zone up to $1050^{\circ}C$. The formation of $Ni_2$Si layers with carbon precipitates alternated periodically with the carbon free layers. At temperatures between $950^{\circ}C$ and $1050^{\circ}C$, the typical layer sequences in the reaction zone is determined by quantitative microanalysis to be $SiC/Ni_2$$Si+C/Ni_2$$Si/Ni_2$$Si+C/…Ni_2$Si/Ni(Si)/Ni. The mechanism of the periodic band structure formation with the carbon precipitation behaviour was discussed in terms of reaction kinetics and thermodynamic considerations. The reaction kinetics is proposed to estimate the effective reaction constant from the parabolic growth of the reaction zone.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.1-10
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• 2018

The amount of biogas increases as the amount of organic waste increases. Recently, biogas from organic waste have been made much efforts to utilize as a energy. In particular, the concentration of $CH_4$ and $CO_2$ generated from sewage sludge and livestock manure treatment are 60-70% and 30-35%, and $CH_4$ and $CO_2$ generated from food wastes are 60-80% and 20-40%. In case of landfill gas, $CH_4$ and $CO_2$ have a concentration of 40-60% and 40-60% respectively. Therefore, in order to use the biogas more widely, it is necessary to convert the biogas to methanol, LNG or DME. In this study, experiments were conducted to produce hydrogen and carbon monoxide through various biogas reforming reactions on $Ni/Ce-ZrO_2/Al2O3$ catalysts. The experiment of synthetic gas synthesis was carried out on a wide concentrations of methane and carbon dioxide, which were the major constituents of biogas from various organic wastes. The effect of $(O_2+CO_2)/CH_4$ (=R') on the yields of hydrogen and carbon monoxide, the conversion rate of methane and carbon dioxide was investigated. Also simulation for syngas synthesis on the $CO_2$ reforming of $CH_4$ was computed by employing total Gibbs free energy minimization method using PRO/II simulator, and compared with the experimental results on wet and dry reforming reaction of biogas.