• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.6 no.4
• /
• pp.609-619
• /
• 1996

Experimental study on effects of factors on the reaction crystallization of silver chloride in rushton type reactor. The size and size distributions of the silver chloride crystals were observed to be markedly affected by the agitation speed of solution, and feeding rate, feeding mode and concentration of reactants. From experimental data it was inferred that in the reaction crystallization of silver chloride the supersaturation level of silver chloride and concentration of excess ions in the solution, and mass transfer rate around the crystals were implicitly interrelated with factors and directly affected on the crystal nucleation and grwoth processes. However, the morphology of the silver chloride crystal was not changed by factors.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.11 no.6
• /
• pp.496-502
• /
• 2006

Off-flavors and unfavorable odors in tuna fish oil were successfully removed and identified using supercritical carbon dioxide extraction, while retaining variable compounds, polyunsaturated fatty acids such as EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). Samples of oil were extracted in a 100 mL semi-batch stainless steel vessel under conditions which ranged from 8 to 20 MPa and $20\;to\;60^{\circ}C$ with solvent ($CO_{2}$) flows from 10 g/min. GC-MS was used to identify the main volatile components contributing to the off-flavors and odors which included 2-methyl-1-propanol, 2,4-hexadienal, cyclopropane, and octadiene. Analyses of oil extracted at $40^{\circ}C$, 20 MPa showed a 99.8% reduction in dimethyl disulfide. Other significant off-flavors identified were 2-methyl-butene, 3-hydroxy butanal and ethylbenzene.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.53 no.1
• /
• pp.63-69
• /
• 2011

The green algae Scenedesmus acuminatus was cultured in different media: animal wastewater and an artificial culture medium in order to evaluate potential use for tertiary treatment. The experiments were conducted with air flowrate 1~2 L/min at $28{\sim}30^{\circ}C$. The nitrogen and phosphorus showed very similar removal efficiencies (68~77 % and 69~80 % for nitrogen and phosphorus respectively). The optimal fed period was estimated as three days in the semi-continuous experiment. The effects of $CO_2$ (4.5 %) injection on nutrient uptake from animal wastewater (biological treatment effluent) were compared to an air injection under the same conditions of light and photoperiod. The uptake rates of nutrient with air injection were observed 0.009 gN/gChl-a/day, 0.028 gN/gChl-a/day and T-P 0.003 gP/gChl-a/day for nitrate, total nitrogen and phosphorus respectively. The rates were enhanced by addition of $CO_2$ to 0.026 gN/gChl-a/day, 0.076 gN/gChl-a/day and T-P 0.018 gP/gChl-a/day. This study establishes that $CO_2$ addition during nutrient deprivation of microalgal cells may accelerate tertiary wastewater treatment.

• Korean Journal of Materials Research
• /
• v.4 no.7
• /
• pp.808-816
• /
• 1994

The work present here shows the technique to produce p-Doped polypyrrole particles by semibatch dispersion polymerization using steric-stabilizer. Monomer-starved polymerization process was successful to increase the particle size up to 50 nm in case of polyvinylalcohol (PVA) stabilizer, and up to 95 nm in case of methylcellulose stabilizer. The particle size and the bulk conductivity changed with the feed rates of monomer, the concentrations of initiator (dopant) and the type, molecular weight, concentrations of steric-stabilizer.

• Journal of the Korean Applied Science and Technology
• /
• v.19 no.2
• /
• pp.131-136
• /
• 2002

As model waterborne acrylic coatings, mono-dispersed poly(butyl acrylate-methyl methacrylate) copolymer latexes of random copolymer and core/shell type graft copolymer were prepared by seeded multi-staged emulsion polymerization with particle size of $180{\sim}200$ nm using semi-batch type process. Sodium lauryl sulfate and potassium persulfate were used as an emulsifier and an initiator, respectively. The effect of particle texture including core/shell phase ratio, glass transition temperature and crosslinking density, and film forming temperature on the film formation and final properties of film was investigated using SEM, AFM, and UV in this study. The film formation behavior of model latex was traced simultaneously by the weight loss measurement and by the change of tensile properties and UV transmittance during the entire course of film formation. It was found that the increased glass transition temperature and higher crosslinking degree of latex resulted in the delay of the onset of coalescence of particles by interdiffusion during film forming process. This can be explained qualitatively in terms of diffusion rate of polymer chains. However, the change of weight loss during film formation was insensitive to discern each film forming stages-I, II and III.

• Korean Journal of Agricultural Science
• /
• v.11 no.2
• /
• pp.322-327
• /
• 1984

As a basic studies for the laboratory scale production of alfalfa inoculum, Rhizobium meliloti M14 was characterized for its carbon and nitrogen sources, and some parameters for broth cultivation in a chemostat were studied by semi-continuous operation. The result s obtained were as follows. 1. Growth rate of the strain was increased by disaccharides than by monosaccharides tested, and pentoses resulted in poor growth than hexoses. Sugar alcohols including inositol supported the best growth among sugars. 2. Mannitol in the yeast-mannitol-broth was substituted by natural carbon sources such as malt extract or molasses. 3. Ten per cent of fresh yeast water appeared to supply enough amount of growth factor s for the strain, and the effect was equivalent to 0.24 percent of the commercial yeast extract powder. 4. Batch growth of the stain in a chemostat, New Brunswick Micro Ferm 28L, reached in the early stationary growth phase of $5{\sim}7{\times}10^9cells/ml$ after 36 hours of incubation. The culture at this stage was switched to semi-continuous cultivation, and the culture broth of four-fifth of the working volume was recovered every 24 hours when the maximal count was obtained.

• KSBB Journal
• /
• v.23 no.5
• /
• pp.413-418
• /
• 2008

The production of 1,3.propanediol (1,3-PD) was investigated with Klebsiella pneumoniae DSM2026 and K. pneumoniae DSM4799 using crude glycerol obtained from biodiesel industry. Crude glycerol was used without prior purification to investigate effects of impurities in crude glycerol on 1,3-PD production. In the batch cultures, 1,3-PD production with crude glycerol was $1.1{\sim}2.5$ times higher than that with pure glycerol, indicating that crude glycerol is even a better substrate than pure glycerol for 1,3-PD fermentation. When glucose was added, 1,3-PD production and yield decreased in spite of enhanced cell growth. Furthermore, the addition of glucose was found to increase 2,3-butanediol, a by-product, significantly because of the change in metabolism in the presence of glucose. In semi-batch cultures without glucose addition, 26 g/L 1,3-PD was produced with crude glycerol, which was $2{\sim}3$ times higher than that with pure glycerol. Based on our results, it was clearly shown that crude glycerol is an effective substrate for biological 1,3-PD production, making it more feasible to produce 1,3-PD at a lower price.

• Journal of Adhesion and Interface
• /
• v.24 no.3
• /
• pp.77-85
• /
• 2023

In this research, polymeric anionic surfactants having various molecular weights and acid values were synthesized using a continuous stirred tank reactor (CSTR). The CSTR has an advantage of higher production rate and more constant product properties compared to batch and semi-batch reactors. The polymeric surfactants were made using butyl acrylate as a hydrophobic group and acrylic acid as a hydrophilic group. The synthesized polymeric surfactants were ionized with alkali solution and were used as an anionic surfactant. To investigate the properties as a surfactant, the properties of the synthesized surfactant, such as acid value, critical micelle concentration (CMC) and molecular weight, were measured. The results showed that the acid values of the polymeric surfactants were 60 to 380 and a number average molecular weight were 8,000 to 13,000 g/mol. Also, it was found that the CMC was around 0.01 g/ml, which showed similar level values with ordinary surfactant. To prove the performance of the polymeric surfactant, acrylic emulsion PSAs were synthesized using the acquired polymeric surfactant. The results showed that the maximum peel strength of 21.24 N/25mm when acid value was 150 and molecular weight was 8,500 g/mol. The values of peel strength and initial tack of acrylic emulsion PSAs using polymeric surfactant synthesized in this study showed much higher than those of reference PSAs synthesized using ordinary anionic surfactant, SDS (Sodium Dodecyl Sulfate) and SDS/TRX (Triton X-100).

• Journal of Microbiology and Biotechnology
• /
• v.23 no.5
• /
• pp.689-698
• /
• 2013

The production and characterization of an active recombinant N-acetylgalactosamine-6-sulfate sulfatase (GALNS) in Escherichia coli BL21(DE3) has been previously reported. In this study, the effect of the signal peptide (SP), inducer concentration, process scale, and operational mode (batch and semi-continuous) on GALNS production were evaluated. When native SP was presented, higher enzyme activity levels were observed in both soluble and inclusion bodies fractions, and its removal had a significant impact on enzyme activation. At shake scale, the optimal IPTG concentrations were 0.5 and 1.5 mM for the strains with and without SP, respectively, whereas at bench scale, the highest enzyme activities were observed with 1.5 mM IPTG for both strains. Noteworthy, enzyme activity in the culture media was only detected when SP was presented and the culture was carried out under semi-continuous mode. We showed for the first time that the mechanism that in prokaryotes recognizes the SP to mediate sulfatase activation can also recognize a eukaryotic SP, favoring the activation of the enzyme, and could also favor the secretion of the recombinant protein. These results offer significant information for scaling-up the production of human sulfatases in E. coli.

• Journal of the Korean Applied Science and Technology
• /
• v.22 no.3
• /
• pp.289-297
• /
• 2005

In order to improve resistant properties of water-borne acrylic pressure sensitive adhesives(PSAs) for automobiles, this study was carried out. Removable PSAs for automobiles were synthesized by emulsion polymerization of monomers, n-butyl acrylate(BA), n-butyl methacrylate(BMA), acrylonitrile(AN), acrylic acid(AA) and 2-hydroxyethyl methacrylate(2-HEMA), and AA and 2-HEMA could act as functional monomers for crosslink. Emulsion polymerization was carried out in a semi-batch type reactor. Water resistance, heat resistance, acid resistance, alkali resistance and smoke resistance were examined. As a result, water resistance increased with the amount of BMA, however, the effect of BMA content on the water resistance was insignificant at a range of over 14 wt%. The water resistance also increased with the amount of functional monomers, AA and 2-HEMA. The prepared PSAs satisfied all the standard for automobiles except heat resistance. However, the heat resistance comes nearly up to the standard. Also, acid resistance, alkali resistance and smoke resistance of the prepared PSAs satisfied with the standard.