• Transactions of the Korean hydrogen and new energy society
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• v.28 no.4
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• pp.384-391
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• 2017

Effects of operating variables on solid circulation rate were measured and discussed using two-interconnected circulating fluidized bed system at ambient temperature and pressure. OCN 706-1100 particles were used as oxygen carrier. The measured solid circulation rates increased as the lower loop seal gas flow rates and the solid height in the fuel reactor increased. Suitable operating conditions to avoid choking of the air reactor were confirmed. Continuous long-term operations of steady-state solid circulation were also demonstrated at two different conditions based on the operating window.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.5
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• pp.46-52
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• 2009

In this study the predictions of NOx in methane-air lean premixed combustion in PSR were carried out with GRI 3.0 methane-air combustion mechanism and Zeldovich, nitrous oxide, prompt, and NNH NO formation mechanism by using CHEMKIN code. The results are compared to the JSR experimental data of Rutar for the validation of the model. This study concerns about the importance of the chemical pathways. The chemical pathway most likely to form the NO in methane-air lean-premixed combustion was investigated. The results obtained with the 4 different NO mechanisms for residence time(0.5-1.6ms) and pressure(3, 4.7, 6.5 atm) are compared and discussed.

• Journal of the Korean Applied Science and Technology
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• v.19 no.1
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• pp.33-42
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• 2002

Copolymerization of ${\alpha}$-Methylstyrene(AMS) with Acrylonitrile(AN) was carried out with benzoylperoxide(BPO) as an initiator in toluene at $80^{\circ}C$ in a continuous stirred tank reactor. Reaction volume and residence time were 0.6 liters and 3 hours, respectively. The monomer reactivity ratios, $r_{AMS}$ and $r_{AN}$ determined by both the Kele$T{\"{u}}d\"{o}s$ method and the Fineman-Ross method were $r_{AMS}$=0.16(0.14), $r_{AN}$=0.04(0.06). The cross-termination factor ${\Phi}$ of the copolymer over the entire AMS composition ranged from 0.75 to 0.92. The ${\Phi}$ factors of poly(AMS-co-AN) were increased with increasing AMS content. The simulated conversions and copolymerization rates were compared with the experimental results. It was observed that the average time to reach dynamic steady-state was three times the residence time.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.279-286
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• 2017

This review paper evaluates different kinds of synthesis methods for calcite precipitated calcium carbonates by using different materials. The various processing routes of calcite with different compositions are reported and the possible optimum conditions required to synthesize a desired particle sizes of calcite are predicted. This paper mainly focuses on that the calcite morphology and size of the particles by carbonation process using loop reactors. In this regard, we have investigated various parameters such as $CO_2$ flow rate, Ca $(OH)_2$ concentration, temperature, pH effect, reaction time and loop reactor mechanism with orifice diameter. The research results illustrate the formation of well-defined and pure calcite crystals with controlled crystal growth and particle size, without additives or organic solvents. The crystal growth and particle size can be controlled, and smaller sizes are obtained by decreasing the Ca $(OH)_2$ concentration and increasing the $CO_2$ flow rate at lower temperatures with suitable pH. The crystal structure of obtained calcite was characterized by using X-ray diffraction method and the morphology by scanning electron microscope (SEM). The result of x-ray diffraction recognized that the calcite phase of calcium carbonate was the dominating crystalline structure.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.7
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• pp.706-712
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• 2006

Recursive Partial Least Squares(RPLS) method has been used for processing the on-line available multivariate chemical process data and modeling adaptive prediction model for process changes. However, RPLS method is unstable in PLS model updating because RPLS method updates PLS model by merging past PLS model and new data. In this study, Adaptive Predictive Partial Least Squres(APPLS) method is suggested for more sensitive adaptation to process changes. By expanding APPLS method, block-wise Adaptive Predictive Partial Least Squares(block-wise APPLS) method is suggested for a lager scale data of chemical processes. APPLS method has been applied to predict the reactor properties and the product quality of a direct esterification reactor for polyethylene terephthalate(PTT), and block-wise APPLS method has been applied to predict the cetane number using NIR Diesel Spectra data. APPLS and block-wise APPLS methods show better prediction and updating performance than RPLS method.

• Korean Journal of Materials Research
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• v.18 no.8
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• pp.406-410
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• 2008

The properties of pyrolytic carbon (PyC) deposited from $C_2H_2$ and a mixture of $C_2H_2/C_3H_6$ on $ZrO_2$ particles in a fluidized bed reactor were studied by adjusting the deposition temperature, reactant concentration, and the total gas flow rate. The effect of the deposition parameters on the properties of PyC was investigated by analyzing the microstructure and density change. The density could be varied from $1.0\;g/cm^3$ to $2.2\;g/cm^3$ by controlling the deposition parameters. The density decreased and the deposition rate increased as the deposition temperature and reactant concentration increased. The PyC density was largely dependent on the deposition rate irrespective of the type of the reactant gas used.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.8
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• pp.613-621
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• 2009

Coal is the energy resource which is important with the new remarking energy resource. Coal combustion produces more NOx per unit of energy than any other major combustion technology. Pollutant emission associated with coal combustion will have a huge impact on the environment. Coal conversion has three processes which are drying, coal devolatilization and char oxidation. Coal devolatilization process is important because it has been shown that HCN which is converted from volatile N contributes 60 to 80% of the total NOx produced. This paper addresses mass release behavior of char, tar, gas and HCN in an experiment of Laminar Flow Reactor with two coals such as Roto middle coal (Sub-bituminous) and Anglo coal (Bituminous). The experiment is compared with the data predicted by CPD model for mass release of HCN about Roto south, Indominco, Weris creek and China orch coals. The results show that HCN increases as a function of decreasing the ratio of fixed carbon(FC)/ volatile matter(VM of the coals contain.)

• Bulletin of the Korean Chemical Society
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• v.24 no.11
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• pp.1623-1626
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• 2003

The dependency of the rate of $CO_2$ reforming of methane on the catalyst loading and the reactor size was examined at a fixed temperature of $750\;^{\circ}C$ and a fixed GHSV of 18000 mL(STP)/$g_{cat}.h$. The conversion of methane in $CO_2$reforming decreased with increase in the reactor size. The catalyst was severely deactivated with increase in the catalyst amount. The amount of carbonaceous species combustible below $550\;^{\circ}C$, determined by TPO experiments with the used catalyst samples increased with increase in the catalyst amount, which was again confirmed by XRD and TEM experiments. The increase of the carbonaceous species combustible below $550\;^{\circ}C$ may be due to the suppression of the reverse Boudouard reaction, since the $CO_2$ reforming of methane, a highly endothermic reaction, resulted in lowering the reaction temperature.

• Journal of the Korean Society of Safety
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• v.20 no.3 s.71
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• pp.84-90
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• 2005

Thermal decomposition of the copolymer of ${\alpha}$-Methylstyrene(AMS) with Acrylonitrile(AN) was investigated. The copolymer was synthesized in a continuous stirred tank reactor(CSTR) at $80^{\circ}C$ using toluene and benzoyl peroxide(BPO) as solvent and initiator, respectively. The reactor volume was 0.3 liters and residence time was 3 hours. The activation energy of thermal decomposition was in the ranges of $34{\sim}54$ kcal/mol for AMS with AN copolymer. The thermogravimetric trace curves were well agreed with the theoretical calculation.

• Environmental Engineering Research
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• v.24 no.2
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• pp.309-317
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• 2019

This study evaluated the kinetics of acrylamide (AM) biodegradation by mixed culture bacteria and Enterobacter aerogenes (E. aerogenes) in sequencing batch reactor (SBR) systems with AQUASIM and linear regression. The zero-order, first-order, and Monod kinetic models were used to evaluate the kinetic parameters of both autotrophic and heterotrophic nitrifications and both AM and chemical oxygen demand (COD) removals at different AM concentrations of 100, 200, 300, and 400 mg AM/L. The results revealed that both autotrophic and heterotrophic nitrifications and both AM and COD removals followed the Monod kinetics. High AM loadings resulted in the transformation of Monod kinetics to the first-order reaction for AM and COD removals as the results of the compositions of mixed substrates and the inhibition of the free ammonia nitrogen (FAN). The kinetic parameters indicated that E. aerogenes degraded AM and COD at higher rates than mixed culture bacteria. The FAN from the AM biodegradation increased both heterotrophic and autotrophic nitrification rates at the AM concentrations of 100-300 mg AM/L. At higher AM concentrations, the FAN accumulated in the SBR system inhibited the autotrophic nitrification of mixed culture bacteria. The accumulation of intracellular polyphosphate caused the heterotrophic nitrification of E. aerogenes to follow the first-order approximation.