• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.337-343
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• 2009

To apply to novel two-interconnected fluidized beds system for selective solid circulation, a solid separator and a solid circulation system were developed. The solid separation rate increased as the gas velocity through the solid injection nozzle, solid height, and diameter of solid injection nozzle increased. However, the effect of the fluidization velocity was negligible. Coarse($212{\sim}300{\mu}m$) and fine($63{\sim}106{\mu}m$) particles were separated using the solid separator and the solid separation rate was ranged from 66 to 453 g/min. The solid circulation rate increased as the gas velocity through the solid injection nozzle, solid height, and the number of solid intake holes increased. However, the effect of the fluidization velocity was negligible. Fine particle was circulated using the solid circulation system and the solid circulation rate was ranged from 65 to 390 g/min. We also proposed two interconnenced fluidized beds system for selective solid circulation equipped with the developed solid separator and the solid circulation system. Long-term operation of continuous solid circulation up to 20 hours has been performed to check feasibility of stable operation. The pressure drop profiles in two beds and the solid separation rate were maintained steadily, and therefore, we could conclude that solid circulation was smooth and stable.

• Korean Journal of Agricultural and Forest Meteorology
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• v.9 no.2
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• pp.75-87
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• 2007

Groundwater recharge rates were estimated and compared in a headwater catchment at the Gwangneung Supersite using three different methods: water-table fluctuation (WTF), mass balance, and hydrograph separation techniques. Data were obtained during the rainy season from June to September 2005. Two different WTF methods estimated the groundwater recharge rate as 25.9% and 23.6%. The mass balance calculation of chloride ions indicated recharge rates of 13.4% on average. Baseflow separation using chloride ion as a tracer from six storm hydrographs produced a 14.0% net baseflow rate on average. Because of the implicit assumption of a long-term steady state without storage change, recharge rates calculated by mass balance and hydrograph separation were smaller than those done with WTF methods, which include the amount of increased storage due to the water-level rise. Subsequently, the WTF method is superior to others in the estimation of groundwater recharge rate to comprehend the dynamic characteristics of the hydrologic cycle.

• Textile Coloration and Finishing
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• v.17 no.4 s.83
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• pp.15-20
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• 2005

Poly(ethylene-co-vinylacetate)(EVA) microspheres were prepared by thermally induced phase separation in toluene. The microsphere formation occurred by the nucleation and growth mechanism in metastable region. The effects of the polymer or pigment weight percentage and cooling rate on microsphere formation were investigated. The microsphere formation and growth were followed by the cloud point of the optical microscope measurement. The microsphere size distribution, which was obtained by particle size analyzer, became broader when the polymer concentration was higher, the pigment concentration and the cooling rate of EVA copolymer solution were lower.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.41 no.3
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• pp.228-231
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• 2008

Two methods for separating dinoflagellate cysts from marine sediments were compared: panning and sodium polytungstate (SPT). After pretreatment with the SPT solution, Protoperidinium species had a high germination rate and cell growth rate. The germinated cells grew continuously, even in a low nutrient environment. Alexandrium cysts did not germinate, because their germination is usually active in winter. Using SPT solution, the separation process was easier, quicker, and caused much less eye fatigue than the panning method. Therefore, SPT solution offers a convenient way of pretreating dinoflagellate cysts for separation and analysis.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.279-280
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• 2006

In the present study the flow fields around pitching foils have been visualized by using a Schlieren method with a high speed camera in a wind tunnel at low Reynolds number regions. It has been observed that small vortices are shed discretely from the leading and trailing edge and that they stand in line on the integrated streakline of separation shear layer. By counting vortices in the VTR frames it was clarified that the number of vortex shedding from the leading and trailing edge during one pitching cycle strongly depends on the non-dimensional pitching rate.

• Proceedings of the Membrane Society of Korea Conference
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• 1995.10a
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• pp.45-46
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• 1995

Generally, two different techniques have been employed for the precipitation of membranes from a polymer casting solution. In the first method, a precipitant is introduced from a vapor phase. In this case the precipitaion rate is very slow and a more or less symmetric structure is formed. In the second method, a precipitant is added to a casting solution by immersing the cast polymer film in a nonsolvent bath. In this case the precipitation rate is very fast and a skinned asymmetric membrane structure is obtained. In this study, we introduced water-vapor to PSf/NMP solution and took photographs of phase separation phenomena of polymer lean phase.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.30B no.4
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• pp.76-84
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• 1993

In this thesis, general method using autoregressive model in the functional separation of the myoelectric signal of human arm movements are suggested. Covariance method and sequential least squares algorithm were used to determine the model parameters and the order of signal model to describe six arm movement patterns` the forearm flexion and extension, the wrist pronation and supination, rotation-in and rotation out. The confidence interval to classify the functions of arm movement was defined by the mean and standard deviation of total squares error. With the error signals of autoregressive(AR) model, the result showed that the highest success, rate was abtained in the case of 4th order, and success rate was decreased with increase of order. This technique might be applied to biomedical-and rehabilitation-engi-neering.

• Progress in Superconductivity and Cryogenics
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• v.21 no.2
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• pp.26-30
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• 2019

Coal is the most abundant fossil fuel on Earth and is used in a wide range of applications. The direct combustion of high-sulfur coal produces a large amount of sulfur dioxide, which is a toxic and corrosive gas. A new superconducting high gradient magnetic separation (HGMS) technology was studied to remove sulfur from high sulfur coal. The magnetic separation concentrate was obtained under the optimum parameters, such as a particle size of -200 mesh, a magnetic field strength of 2.0 T, a slurry concentration of 15 g/L, and a slurry flow rate of 600 ml/min. The removal rate of sulfur is up to 59.9%. The method uses a magnetic field to remove sulfur-containing magnetic material from a pulverized coal solution. It is simple process with, high efficiency, and is a new way.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.615-619
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• 2009

(+)-$Tr{\ddot{o}}ger$'s base in $Tr{\ddot{o}}ger$'s base racemates that inhibits thromboxane A2($T{\times}A2$) synthase has been used to treat arteriosclerosis. Separation of (+)-$Tr{\ddot{o}}ger$'s base by chromatography has become a major concern. However separation experiments of (+)-$Tr{\ddot{o}}ger$'s base need time and consumables so that simulation with Aspen Chromatography could save time and costs by predicting the efficiency of separation. Injection amount and eluent flow rate were varied to compare the resolutions and yields of TB(-) and TB(+). Highest resolution and yield were attained at the eluent rate of 0.25 mL/min. Isotherms representing the relationship between mobile phase concentration and stationary phase concentration were changed to get the best separation with Ideal Adsorbed Solution(IAS) Statistical Lanmuir isotherms.

• Korean Journal of Food Science and Technology
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• v.19 no.3
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• pp.225-230
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• 1987

The foam separation of bovine serum proteins was investigated and the protein fractionation by foam separation was analyzed by PAG electrophoresis. The protein concentration for the surface excess formation of bovine serum was in the range of $20-800\;{\mu}g/ml$. At pH 5, the foamate volume was maximum, but the enrichment ratio minimum. As the temperature was elevated, the foamate volume decreased and the enrichment ratio increase. As the gas flow rate increased from 25 to 100 ml/min, the foamate volume decreased and the enrichment ratio increased. The enrichment ration became maximum when the added ionic strength of serum solution was in the range of 1-3 by the addition of different types of salts, and this was related to the reduction of surface tension of the solution. In general, BSA, ${\alpha}_1$, and ${\alpha}_2-globulins$, which have relatively small molecular weight and high hydrophobicity, moved easily to the foam, and the separation of protein fractions in the serum varied with the changes in pH, temperature, gas flow rate and ionic strength of the solution.