• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.3
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• pp.545-550
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• 2017

As an alternate technique for water softening, high voltage impulse (HVI) is introduced and verified if it can control the $CaCO_3$ scale formation in industrial water treatment. After HVI was applied to the artificial hard water containing $100{\pm}5mg/L$ $Ca^{2+}$ for 4 hours, the $Ca^{2+}$ concentration and the electrical conductivity were measured. The concentration of $Ca^{2+}$ was reduced from 94.5 to 86.3 mg/L (8.7% reduction) after 4 hour contact of HVI under 5 kV condition. The $Ca^{2+}$ was decreased from 92 to 77.7 mg/L (15.6% reduction) at 8kV and from 90.1 to 75.4 mg/L (16.3% reduction) at 12 kV condition. Both of the contact time and the applied voltage were important parameters affecting the calcium ion reduction. With these results, it was verified that HVI technique could be potential candidate for control of $CaCO_3$ scale formation.

• Korean Journal of Materials Research
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• v.26 no.11
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• pp.628-634
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• 2016

The cold rolling workability and mechanical properties of two new alloys, designed and cast Al-5.5Mg-2.9Si and Al-7Mg-0.9Zn alloys, were investigated in detail. The two alloy sheets of 4 mm thickness, 30 mm width and 100 mm length were reduced to a thickness of 1 mm by multi-pass rolling at ambient temperature. The rolling workability was better for the Al-7Mg-0.9Zn alloy than for the Al-5.5Mg-2.9Si alloy; in case of the former alloy, edge cracks began to occur at 50% rolling reduction, and their number and length increased with rolling reduction; however, in the latter alloy, the sheets did not have any cracks even at higher rolling reduction. The mechanical properties of tensile strength and elongation were also better in the Al-7Mg-0.9Zn alloy than in Al-5.5Mg-2.9Si alloy. Work hardening ability after cold rolling was also higher in the Al-7Mg-0.9Zn alloy than in the Al-5.5Mg-2.9Si alloy. At the same time, the texture development was very similar for both alloys; typical rolling texture developed in both alloys. These differences in the two alloys can primarily be explained by the existence of precipitates of $Mg_2Si$. It is concluded that the Al-7Mg-0.9Zn alloy is better than the Al-5.5Mg-2.9Si alloy in terms of mechanical properties.

• Korean Journal of Microbiology
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• v.36 no.4
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• pp.279-284
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• 2000

Simultaneous reduction of Cr(VI) and degradation of phenol was observed in batch and bench-scale continuous stirred tank reactors using Rhodococcus sp. CP01 isolated from leachate. The strain CP01, which was capable of utilizing phenol as a sole source of carbon and energy, completely reduced added hexavalent chromium (0.25 mM) to its trivalent form during 60 hr batch assay under optimal conditions (pH 7.0 and 1,000 mg/L of phenol concentration). The rates of Cr(VI) reduction and phenol degradation were estimated as 4.17 $\mu$M Cr(VI) and 38.4 mg phenol.$L^{-1}{\cdot}hr^{-1}$, respectively. The continuous culture experiment was conducted for 46 days using synthetic feed containing different levels of chromate (0.0625 to 0.25 mM) and phenol(1,000 to 4,000 mg/L). With a hydraulic retention time of 100 hr, Cr(VI) reduction efficiency was mostly 100% for influent Cr(VI) and phenol concentrations of 0.125 mM and 3,000 mg/L, respectively. During quasi-steady-state operation, specific rate of Cr(VI) reduction was calculated as 0.34 mg Cr(VI).g $protein^{-1}{\cdot}hr^{-1}$ which was comparable to reported values obtained by using glucose as growth substrate. The results suggest the potential application of biological treatment for detoxification of wastewater contaminated simultaneously with Cr(VI) and pheonol.

• KSBB Journal
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• v.19 no.2
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• pp.154-158
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• 2004

Recycled packed-bed reactor emploring immobilized microorganism was suggested in this paper for efficient denitrification. In the batch reactor, the effects of initial oxidation-reduction potential and nitrate concentration on denitrification were investigated. As the initial oxidation-reduction potential was decresed to -70 mV from ＋40 mV, the removal rate of nitrate was increased to 3.33 from 1.25 m9 NO$_3$$\^$-/-N/min under the experimental conditions. As the initial nitrate-N concentraion was increased to 200 mg/l, the removal rate of nitrate was proportional to the concentration of nitrate. When the concentration of nitrate-N was 400 mg/min, nitrite was detected, and when the initial nitrate-N concentration was reached at 1,000 mg/l, it took longer time for the complete nitrate removal. In order to decrease the initial oxidation-reduction potential and the nitrate-N concentration in the feed stream, the effluent was recycled to the influent stream in the packed-bed reactor. In the case of recycling, the initial oxidation-reduction potential was decreased to 30 mV from 150 mV, and the initial nitrate concentration could be decreased to 85 from 120 mg NO$_3$$\^$-/-N/l. As the result of recycling, the removal rate of nitrate was increased to 91.7% from 49.2%.

• YAKHAK HOEJI
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• v.25 no.3
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• pp.109-114
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• 1981

The authors investigated drug interaction of ibuprofen and prednisolone in antiinflammatory and antipyretic activities. We have found significant differences of the antiinflammatory and antipyretic activities between single and concurrent administration of ibuprofen and prednisolone, using Sprague-Dawley Strain rats, carrageenin as a phlogistic agent and brewer's yeast as a fever inducing agent. 1) Ibuprofen(20mg/kg) was administered to the rats orally and resulted in significant reduction of (31.70 %) the swelling of rat paw induced by carrageenin, 2) prednisolone (9mg/kg) showed significant reduction of (45.76%) the swelling, 3) concurrent administration of ibuprofen (20mg/kg) and prednisolone (9mg/kg) also reduced (57.40%) the swelling. In ibuprofen (125mg/kg) administration, the inhibition rate of edema was 39.32% and in prednisolone (1mg/kg) administration, the rate was 39.04%. In concurrent administration of ibuprofen (125mg/kg) and prednisolone (1mg/kg), the inhibition rate of edema was 63.09%. Concurrent administration of ibuprofen and prednisolone showed more anti-inflammatory effects than single administration of ibuprofen and prednisolone respectively. Prednisolone itself did not show antipyretic effect, but concurrent administration of ibuprofen and prednisolone showed more antipyretic effects than ibuprofen single administratron.

• Journal of Powder Materials
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• v.20 no.1
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• pp.43-47
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• 2013

The extraction of metallic pure vanadium powder from raw oxide has been tried by Mg-reduction. In first stage, $V_2O_5$ powders as initial raw material was reduced by hydrogen gas into $V_2O_3$ phase. $V_2O_3$ powder was reduced in next stage by magnesium gas at 1,073K for 24 hours. After reduction reaction, the MgO component mixed with reduced vanadium powder were dissolved and removed fully in 10% HCl solution for 5 hours at room temperature. The oxygen content and particle size of finally produced vanadium powders were 0.84 wt% and 1 ${\mu}m$, respectively

• Journal of Microbiology and Biotechnology
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• v.20 no.8
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• pp.1230-1239
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• 2010

Five bacterial species, capable of degrading the recalcitrant organic compounds (ROCs) diethyleneglycol monomethylether (DGMME), 1-amino-2-propanol (APOL), 1-methyl-2-pyrrolidinone (NMP), diethyleneglycol monoethylether (DGMEE), tetraethyleneglycol (TEG), and tetrahydrothiophene 1,1-dioxide (sulfolane), were isolated from an enrichment culture. Cupriavidus sp. catabolized $93.5{\pm}1.7$ mg/l of TEG, $99.3{\pm}1.2$ mg/l of DGMME, $96.1{\pm}1.6$ mg/l of APOL, and $99.5{\pm}0.5$ mg/l of NMP in 3 days. Acineobacter sp. catabolized 100 mg/l of DGMME, $99.9{\pm}0.1$ mg/l of NMP, and 100 mg/l of DGMEE in 3 days. Pseudomonas sp.3 catabolized $95.7{\pm}1.2$ mg/l of APOL and $99.8{\pm}0.3$ mg/l of NMP. Paracoccus sp. catabolized $98.3{\pm}0.6$ mg/l of DGMME and $98.3{\pm}1.0$ mg/l of DGMEE in 3 days. A maximum $43{\pm}2.0$ mg/l of sulfolane was catabolized by Paracoccus sp. in 3 days. When a mixed culture composed of the five bacterial species was applied to real wastewater containing DGMME, APOL, NMP, DGMEE, or TEG, 92~99% of each individual ROC was catabolized within 3 days. However, at least 9 days were required for the complete mineralization of sulfolane. Bacterial community diversity, analyzed on the basis of the TGGE pattern of 16S rDNA extracted from viable cells, was found to be significantly reduced in a conventional bioreactor after 6 days of incubation. However, biodiversity was maintained after 12 days of incubation in an electrochemical bioreactor. In conclusion, the electrochemical reduction reaction enhanced the diversity of the bacterial community and actively catabolized sulfolane.

• Journal of Environmental Health Sciences
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• v.27 no.2
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• pp.73-81
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• 2001

The purpose of this study was to determine the adverse effects of methylmercuric chloride(MMC) against the fetal growth and the ossification rate of fetal pectoral and pelvic girdle, stermebrae, ribs and tail in pregnant Fischer 344 rats administered orally on day 7 of gestation. The resulted obtained are as follows. The weight and size of fetus were highly reduced by MMC. The reduction of fetal weight and size were 16. 2%~24.5%(p<0.01), and 34.1%~48.8%(p<0.01), and that of the litter’s weight were 67.0%(p<0.01) and 89.2%(p<0.01) by 20 and 30mg/kg MMC, respectively. Ossification centers were never formed in pectoral and pelvic phalanges and sternebrae, and was reduced as much as 70% in tail by 30mg/kg MMC. And also those were 82.4%~ 91.2%(p<0.01) in ischium, and 52.4~66.7%(p<0.01) in the others(ilium, fenur, tibia, fibula, metatarsals)of pelvic girdle by 30 mg/kg MMC. Ossification of sternebrae was terrible. 5th bone of sternebrae was not ossificated by 20 and 30 mg/kg MMC(p<0.01), and 2nd was also not ossificated by 30 mg/kg MMC(p<0.01).And reduction of ossification rate was 84.8~97.8%(p<0.01) in the others of sternebrae by 30 mg/kg MMC. And then, the reduction of ossification rate was 26.65~49.8%(p<0.01) in fetal ribs by 30 mg/kg MMC, and they were trend to increased as following from center to each edge. In conclusion, it was observed that fetal weight, size, and ossification of each bone were highly significantly reduced by the increased dosage of MMC.

• KSBB Journal
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• v.11 no.6
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• pp.630-635
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• 1996

Blood plasma proteins dissolved in isotonic phosphate-buffered saline were found to be adsorbed to red blood cell ghosts suspended in the solution. This was evidenced by concentration reduction of the plasma proteins in the bulk solution. For initial concentration of 0.1mg/mL immuno globulin, concentration reduction increased from 14% to 45% as the volume fraction of red blood cell ghosts in the solution increased from 5% to 45%. For initial concentration of 0.075mg/mL albumin, the concentration reduction increased from 12% to 47% as the volume fraction of red blood cell ghosts in the solution increased from 5% to 70%. The concentration reduction of plasma proteins in hardened red blood cell ghosts was higher than that in red blood cell ghosts. The number of adsorbed protein molecules per a red blood cell ghost were reduced as volume fraction of the ghosts in the solution increased.

• Journal of Korea Foundry Society
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• v.26 no.3
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• pp.146-151
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• 2006

In this study, effects of CaD and Ca addtions on microstructure and ignition resistance of pure Mg were investigated. With increasing Ca and CaO contents, the grains in Ca and CaO added Mg were refined and ignition temperatures of CaO and Ca added Mg increased, too. As a result of phase analysis, CaO seemed to be reduced to Ca. $Mg_2Ca$ phase was formed even in 0.1 wt%CaO added pure Mg by reduction mechanism, while $Mg_2Ca$ phase was formed in over 1.35 wt% Ca added pure Mg. Thermodynamical consideration for the reduction mechanism of CaO in pure Mg was carried out.