• KLA journal
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• no.5-6
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• pp.2-7
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• 1958

• Journal of the Korean Institute of Telematics and Electronics T
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• v.35T no.2
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• pp.66-71
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• 1998

A compact ESP of two-stage type is widely used with positive corona discharge in working environment where the production of ozone is extreamly prohibited. Since there are few scientific reports on a compact ESP, we have investigated the fundamental characteristics of a two-stage ESP. A model two-stage ESP is made with simple structure in order to simplify theoretical analysis and the relative position of the ionizer and collector section can be changed. The experimental investigation revealed many interesting facts.: The electric field in the collector electrodes affects the corona discharge of the ionizer. The concentration of particles after collector remarkably varied in the region between the high voltage and grounded electrodes. The collection efficiency right behind the high voltage electrode is much greater than that behind the grounded one. The total collection efficiency, calculated by integrating the particle concentration in whole measuring region, is greater when the high voltage electrode of the collector is located behind the discharge electrode of ionizer. Thus, the relative position of the ionizer and collector electrodes affects the precipitation characteristics.

• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.704-709
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• 2011

Depolymerization of fucoidan induced by contact glow discharge electrolysis(CGDE) was investigated. To utilize fucoidan as a functional food material after CGDE, organic acids were used as a electrolyte in CGDE process. Experimental results showed that CGDE using organic acid reduced the molecular weight of fucoidan effectively. As electrolyte concentration increased, onset voltage of glow discharge decreased and onset current of glow discharge increased. From the variation of molecular weight of fucoidan with the reaction time, it was demonstrated that the degradation of fucoidan followed a first-order rate law. Molecular weight of fucoidan treated with CGDE using organic acid was about 77 times lower compared to initial fucoidan with little free sulfate.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.4
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• pp.295-302
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• 2014

This study demonstrates a double-path CDI as an alternative of advanced wastewater treatment process. While the CDI typically consists of many pairs of electrodes connected in parallel, the new double-path CDI is designed to have series flow path by dividing the module into two stages. The CFD model showed that the double-path had uniform flow distribution with higher velocity and less dead zone compared with the single-path. However, the double-path was predicted to have higher pressure drop(0.7 bar) compared the single-path (0.4 bar). From the unit cell test, the highest TDS removal efficiencies of single- and double-path were up to 88% and 91%, respectively. The rate of increase in pressure drop with an increase of flow rate was higher in double-path than single-path. At 70 mL/min of flow rate, the pressure drop of double-path was 1.67 bar, which was two times higher than single-path. When the electrode spacing was increased from 100 to $200{\mu}m$, the pressure drop of double-path decreased from 1.67 to 0.87 bar, while there was little difference in TDS removal. When proto type double-path CDI was operated using sewage water, TDS, $NH_4{^+}$-N, $NO_3{^-}$-N and $PO_4{^{3-}}$-P removal efficiencies were up to 78%, 50%, 93% and 50%, respectively.

• Korean Chemical Engineering Research
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• v.46 no.5
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• pp.886-891
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• 2008

Contact glow discharge electrolysis(CGDE) is an unconventional electrolysis where plasma is sustained by D.C. glow discharge between an electrode and the surface of electrolyte surrounding it at high voltage. In this study, the behavior of CGDE in NaCl solution and the depolymerization of fucoidan by CGDE were investigated. After onset of CGDE, increase of voltage enhanced Glow discharge which resulted in low current density and low temperature in NaCl electrolyte. From the variation of molecular weight of fucoidan with the reaction time, it was demonstrated that the degradation of fucoidan followed a first-order rate law. Molecular weight of fucoidan treated with CGDE was about 40 times lower compared to initial fucoidan without content decrease of sulfate and fucos.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.604-609
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• 2012

Properties of fucoidan used for functional cosmetic ingredients and the effect of fucoidan molecular weight on the cosmetic functions were studied. Fucoidan was extracted from Undaria pinnatifida sporophylls and molecular weight (35~160 kDa) of fucoidan was controlled by contact glow discharge electrolysis (CGDE). To test possibility of fucoidan as a cosmetics material, tyrosinase inhibition property, water-holding property, elastase activity inhibition property and DPPH free radical scavenging property were measured. Water-holding property of fucoidan was higher than that of hyaruronic acid, which is known as the one of the best water-holding material. The water-holding strength of fucoidan slightly increase as molecular weight of fucoidan decrease. Elastase activity inhibition (anti wrinkle effect) of fucoidan was higher than that of adenosine using standard material for anti wrinkle test. Optimum molecular weight of fucoidan to obtain highest tyrosin inhibition effect, elastase inhibition effect and radical scavenger effect is 100 kDa.

• Korean Chemical Engineering Research
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• v.48 no.1
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• pp.27-32
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• 2010

Properties of fucoidan used for functional cosmetics agents were studied. Fucoidan was extracted from Undaria pinnatifida sporophylls. To test possibility of fucoidan as a cosmetics material, water-holding property measurement, DPPH free radical scavenging assay and MTT assay were done. Water-holding property of fucoidan was higher than that of hyaruronic acid, which is known as the one of the best water-holding material. The water-holding strength of fucoidan slightly increase as molecular weight of fucoidan decrease. Fucoidan showed high stability from MTT assay and good anti-oxidation property from DPPH assay. To evaluate the effect of water-holding property and anti-alergy property of fucoidan on the atopic dermatitis(AD), 46 AD patients were treated with fucoidan cream. After 6 weeks treatment, Investigation Global Assessment(IGA) scores decreased from 3.04 to 2.15, that is fucoidan cream had a 39.8% benefit effect on atopic dermatitis.

• Microbiology and Biotechnology Letters
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• v.20 no.6
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• pp.668-676
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• 1992

For the purpose of optimizing poly-l3-hydroxybutyrate (PHB) production from Alcaligenes eutrophus, two-stage fed-batch culture was adopted. In this system, specifk growth rate was maximized during the first stage whereas specific production rate was maximized during the second stage. The optimal concentrations of glucose and ammonium chloride were 16.6 and 0.54 g/I in the growth stage and 20.0 and 0.07 g/l in the production stage, respectively. Proportional feedback control considering time lag was suggested for PHB production process and a simulator was developed for real-time control purpose.

• KSBB Journal
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• v.15 no.5
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• pp.489-496
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• 2000

Several culture systems including batch, two-stage CSTR, semi-fed batch, and two-stage cyclic fed-batch were investigated for the efficient production of the Fab fraction of PDC-E2 specific human monoclonal antibody using high cell density recombinant E. coli. A two-phase batch system and a two-stage continuous system were examined to overcome plasmid instability problems, by separating the growth and the production stages. The cell density and productivity of the two-stage continuous culture was better than that of the two-phase batch fermentation. In the two-stage continuous culture system with DO-stat, the cell growth and the productivity were superior to those of the system without the DO control. Also, almost total plasmid stability was maintained in the two-stage continuous culture system. Modified M9 medium was selected as an optimum feeding medium for the fed-batch process, and the optimum C/N ratio determined to be 2:3. The optimum feeding rate was $0.6g/\ell/hr$ for a constant feeding strategy in semi-fed batch system. When the feeding medium was fed by pulsing, it was observed that more frequent pulsing resulted in improved cell growth. The linear feeding method was the most efficient of the various feeding methods tested. Finally, high cell density culture using a two-stage cyclic fed batch system with pH-stat was tried because the linear feeding method showed limitations in terms of obtaining high cell densities, and a cell density of $54 g/\ell$ was achieved. It was concluded that the two-stage cyclic fed batch system was the most efficient system for high cell density culture of the systems tested. However, productivity improvements were lower than expected due to the extremely high accumulations of acetate, although the low levels of residual glucose were maintained.

• Tunnel and Underground Space
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• v.20 no.5
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• pp.360-368
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• 2010

The paper presents a case study from a surface mine where the controlled augmentation of throw and drop of the blasted muck piles was warranted to spread the muck piles on the lower berm of the bench. While the augmentation of throw increased the lateral spread and the looseness of the broken muck, the augmentation of drop significantly lowered the muck pile height for easy excavation by the excavators. In this light, the present paper highlights and discusses some pertinent changes in the blast design parameters for such specialized application of cast blasting in a surface mine, where a sandstone bench, with average height of 22-24 m was to be made amenable for excavation by 10 m3 rope shovels, which possessed maximum digging capability of up to 14 m. The results of tailoring the blast design parameters for augmentation of throw and drop are compared with the baseline blasts which were earlier practiced on the same bench by dividing the full height of the bench in 2-slices; upper slice (10-14 m high) and lower slice (12-15 m high). Results of fragment size, its distribution and total cycle time of excavator (shovel) are presented, and discussed.