• YAKHAK HOEJI
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• v.37 no.1
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• pp.66-75
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• 1993

Dental abrasive, dicalcium phosphate dehydrate (DCPD) was prepared and the several important factors affecting on the quality of toothpaste were investigated by means of set test, glycerine absorption, Coulter counter test, color difference, BET adsorption, mercury porosimetery, and rheogram comparing with two foreign DCPDs, MFO4 and Dentphos K. Sample DCPD was prepared by reaction between 85% H$_{3}$PO$_{4}$ and 15% milk of lime at $39^{\circ}C$ (pH6.5), and stabilized with TSPP and TMP. The physicochemical properties of Sample DCPD were obtained as follows: whiteness (98.99), average particle size (15.5 $\mu\textrm{m}$), pH (7.9), remainder particle weight (0.49w/w%), glycerine absorption value (64 ml), and set test (passed). N$_{2}$ adsorption curves (BET) of three kinds of DCPD showed non-porous type III isotherm. BET adsorption parameters of sample DCPD showed that surface area was 24.9 m$^{2}$/g, total pore volume 0.09 cm$^{3}$/g and average pore radius 72.0 $\AA$. The rheogram of the toothpaste containing each DCPD showed bulged plastic flow with yield vlaue and thixotropic behavior. These results meet standard requirements as abrasive standard, and suggested that synthesized sample DCPD could be used a dental abrasive such as a high quality grade in practice as foreign DCPDs.

• Journal of Environmental Science International
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• v.5 no.1
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• pp.43-50
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• 1996

Thiobacillus neopolitanus R-10, which produces a active thiosulfate oxidase was isolated from nightsoil. The optimal culture conditions of Thiobacillus neopolitanus R-10 for the production of enzyme was determined as followed: 0.8% $Na_2S_2O_3$, 0.2% $KH_2PO_4$, 0.2% $K_2HPO_4$, 0.04% $Na_2CO_3$, 0.02% $MgSO_4$.$7H_2O$, 2ml trace elements solution, ann PH 6.5 at 3$0^{\circ}C$ and 72hr cultivation. The oxidase was successively purified 83 folds yield by ${(NH_2)}_2SO_4$ fractionation, DEAE-Cellulose, Sephadex A-50 column chromatogrophy and gel Sephadex G-150 gel filteration with yield of 5.9%. The molecular weight of purified enzyme was estimated to be 43.000 dalton by SDS-polyacrylamide gel electrophoresis and gel filteration column chromatography The enzyme activity was highest at 40t and PH 7.0 The enzyme activity was relatively high by $\beta$-mercaptoethanol but strongly inhibited by cysteine.

• Journal of the Korean Ceramic Society
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• v.44 no.5 s.300
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• pp.144-147
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• 2007

Calcium metaphosphate (CMP) nanofibers with a diameter of ${\sim}600nm$ were prepared using electrospun CMP/polyvinylpyrrolidone (PVP) fibers through a process of drying for 5 h in air followed by annealing for 1 h at $650^{\circ}C$ in a vacuum. The viscosity of the CMP/PVP precursor containing 0.15 g/ml of PVP was 76 cP. Thermal analysis results revealed that the fibers were crystallized at $569^{\circ}C$. The crystal phase of the as-annealed fiber was determined to be ${\delta}-CMP\;({\delta}-Ca(PO_3)_2)$. However, the morphology of the fibers changed from smooth and uniform (as-spun fibers) to linked-particle characteristics with a tubular form most likely due to the decomposition of the inner PVP matrix. It is expected that this large amount of available surface area has the potential to provide unusually high bioactivity and fast responses in clinical hard tissue applications.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.560-566
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• 1996

A strain capable of producing thermostable chitinase suitable for chitooligosaccharide production was isolated from high temperature environment and identified as Bacillus licheniformis. The chitinase from Bacillus licheniformis KFB-Cl4 was only induced by addition of colloidal thitin into the basal medium as carbon source, showing the decrease of the chitinase production by supplernental addition of other carbon sources into the medium containing 1.0% colloidal chitin. Among organic and inorganic nitrogen sources, yeast extract was the most effective for the increase of total activity and specific activity, and had high affinity for the enzyme production. The optimum temperature of cell growth and thermostable chitinase production was 55$\circ$C. The optimum culture medium was composed of 1.2% colloidal chitin, 0.15% K$_{2}$HPO$_{4}$, 0.05% KH$_{2}$PO$_{4}$, 0.01% MgSO$_{4}$-7H$_{2}$O, 0.1% yeast extract (pH 6.5). Bacillus licheniformis KFB-C14 produced the thermostable chitinase of 3.89 units per ml culture fluid and 7.4 units per mg protein under rotary shaking at 150 rpm for 40 hr.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.22-30
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• 1982

Water quality of downstream of the Nagdong river, using for agricultural irrigation of the Gimhae plain, were observed. Water temperature, turbidity, residue, pH, BOD, COD, DO, hardness, chloride, sulphate, phosphate, inorganic nitrogenous compounds, sodium, general bacteria, E. coli and heavy metals of the water were investigated at Daejeo, Sikman, Bongrim, Noksan, Machal and Jangyou pumping stations in the Gimhae plain in May, July and October, 1981. The results obtained were as follows; 1) Average value of analyzed components of the water at all sampling sites were 7.8 pH, 6.3 ppm BOD, 6.5 ppm COD, 6.4 ppm DO, 231 ppm hardness, 582 ppm Cl-, 412 ppm $SO_4--$, 2.32 ppm $PO_4---$, 3.8 ppm $NH_4+,\;478\;ppm\;Na+$, 2964 No. /100 ml total coliform, 0.0040 ppm Cd, 0.0066 ppm Pb, respectively. 2) The most heavily polluted site of all investigated ones was Sikman. It seemed to be caused by the vast quantity of wastewater discharged from industrial district in Gimhae city. The next polluted sites were Bongrim, Daejeo and Noksan, and comparatively less polluted sites were Machal and Jangyou, judging from both appearance and physicochemical observation. 3) At Sikman, the most heavily polluted site, average value of components were 8.0 pH, 8.1 ppm BOD, 8.2 ppm COD. These values were close to the limit point of agricultural water quality standard of 8.0 ppm BOD (COD). 4) Any apparent variation was not observed by the sampling season in most components except DO and $NH_4+$. DO of October was higher than that of May or July but $NH_4+$ was low. 5) $NH_4+$ content was comparatively high in downstream of the Nagdong river of which water is used as the agricultural irrigation in the Gimhae plain. Therefore, fertilizer application on the farming land must make account of nitrogen content of the irrigation water 6) It was considered that chloride and sodium contents would not influence the crop cultivation in common season, but in dry season irrigation must be done carefully.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.317-323
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• 2014

Violacein has received much attention due to its various important biological activities, including broad-spectrum antibacterial and antifungal activity, anti-malarial, anti-tumoral, anti-oxidant, and anti-diarrheal activities. EP15224 strain isolated from forest soils in Korea was found to be a new species belonged to the genus Massilia based on its 16S ribosomal DNA sequences. The 16S ribosomal DNA of strain EP15224 displayed 97% homology with Massilia sp. BS-1, the nearest violacein-producing bacterium. Strain EP15224 produced bluish-purple pigment well in a synthetic MM2 medium containing glucose, $(NH_4)_2SO_4$, $Na_2HPO_4{\cdot}7H_2O$, $KH_2PO_4$, $MgSO_4{\cdot}7H_2O$, and 1 mM $\small{L}$-tryptophan. The chemical analysis of the pigment by LC/MS/MS showed that it is violacein with molecular weight of 343.34. This is the second report on the production of violacein by a Massilia species. In this study, the optimal culture conditions for violacein production were established under which 280 mg/l crude violacein was produced : glucose 2 g/l, $(NH_4)_2SO_4$ 1 g/l, $Na_2HPO_4{\cdot}7H_2O$ 2 g/l, $KH_2PO_4$ 1 g/l, $MgSO_4{\cdot}7H_2O$ 0.1 g/l, L-tryptophan 0.24 g/l, 25 ml medium in a 250 ml flask, with an inoculumn size of 10% (v/v), 72 h of cultivation with 250 rpm at $25^{\circ}C$.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.6
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• pp.511-522
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• 1984

The Nagdong is one of the biggest rivers in Korea, which is very important water source not only for tap water of Pusan city but also for the industrial water. Therefore, authors tried to check the water quality year by year. In this experiment one hundred and twenty water samples collected from August 1983 to July 1984 were analyzed bacteriologically and physiologically. Fifteen sampling stations were established between near Samrangjin and estuary of the river. To evaluate the water quality, temperature, pH, chloride ion, salinity, chemical oxygen demand (COD), electrical conductivity, nutrients, total coliform, fecal coliform, fecal streptococcus, viable cell count and bacterial flora were observed. The variation of water temperature was ranged $-1.5{\sim}29.0^{\circ}C$ (Mean value $13.9{\sim}16.5^{\circ}C$), it in spring was higher as $10{\sim}15^{\circ}C$ about $10^{\circ}C$ than in winter and it in autumm was very stabilized as about $20^{\circ}C$ at each station. The pH variation of the samples was ranged $6.68{\sim}9.15$. The range of concentration of chloride ion and salinity varied $7.4{\sim}l,020.5$ mg/l and $1.05{\sim}33.0\%0$, respectively. Especially, salinity of the 3rd water war was the higher than others as $25.76{\sim}31.58\%0$. COD was ranged $1.45{\sim}14.94$ mg/l and the lower part of the Nagdong River was heavily contaminated by domesitc sewage and waste water from the adjacent factor area. The range of electrical conductivity was $1.360{\times}10^2{\sim}5.650{\times}10^4{\mu}{\mho}/cm$ and that was by far higher the estuary than the upper. Concentration of nutrients were $0.008{\sim}0.040$ mg/l (Mean value $0.019{\sim}0.068$ mg/l) for $NO_2-N,\;0.038{\sim}5.253$ mg/l ($0.351{\sim}2.347$ mg/l) for $NO_3-N,\;0.100{\sim}2.685$ mg/l($0.117{\sim}1.380$ mg/l) for $NH_4-N,\;0.003{\sim}0.084$ mg/l($0.014{\sim}0.065$ mg/l) for $PO_4-P$ and $0.154{\sim}6.123$ mg/l ($1.165{\sim}3.972$ mg/l) for $SiO_2-Si$, respectively. Usually nutrients contents of the water in the upper part(included station 1 to 5) were higher than those of the estuarine area. The bacterial density of the samples ranged 7.3 to 460,000/100 ml for total coliforms, 3.6 to 460,000/100 ml for fecal coliform, $0{\sim}46,000/100ml$ for fecal streptococcus and $<30{\sim}1.2{\times}10^5/ml$ for viable cell count. Composition of coliform was $28\%$ Escherichia coli group, $18\%$ Citrobacter freundii group, $31\%$ Enterobacter aerogenes group and $22\%$ others. Predominant species among the 659 strains isolated from the samples were Pseudomonas spp. ($42\%$), Flavobacterium spp. ($20\%$) and Moraxella spp. ($12\%$).

• Applied Biological Chemistry
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• v.41 no.6
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• pp.465-470
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• 1998

For the need of bio-degradable flocculant in stage of wastewater treatment, some cultural conditions of bioflocculant production were optimized with Aeromonas hydrophila KH-54. About 260 strains of type culture and bacteria isolated from marsh, pond, activated sludge, etc were examined for their ability to flocculate kaolin particles and swine wastewater. Among them, KH-54 showed the highest flocculating activity and was identified as Aeromonas hydrophila according to the cultural, morphological and physiological properties. The maximum production of the flocculant secreted by Aeromonas hydrophila KH-54 was observed in culture medium containing 2.0% mannitol, 0.05% ammonium chloride, 0.02% potassium phosphate dibasic, 0.01% $MgSO_4{\cdot}7H_2O$ and 0.05% yeast extract at initial pH 7.0 when cultured on rotary shaker controlled at $25^{\circ}C$ and 150 rpm. Under the optimized condition, the flocculating ability reached to 770 units/ml of kaolin flocculating activity and 81% of NTU removal efficiency against swine wastewater after 4 days cultivation. The bioflocculant was also effective on various organic wastewaters other than swine wastewater, showing NTU removal rate ranging from 92% to 34%.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.4
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• pp.347-355
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• 1986

The Sonakdong river is very important water source not only for agricultural water of Kimhae field but also for fishery water. Recently the middle and lower areas of the river have the tendency to be heavily contaminated by domestic sewage and agricultural chemicals. Fifty six water samples were collected from 8 stations from July to December in 1985 for the experiment (Fig. 1). To evaluate the water quality, pH, water temperature, electrical conductivity, chloride ion, nutrients ($NO^{-}_{2}-N,\;NO^{-}_{3}-N,\;NH^{+}_{4}-N,\;PO^{3-}_{4}-P,\;SiO_2-Si$), total coliform, fecal coliform, and fecal streptococcus were determined. Range and mean value of the samples were as follows; pH $6.3{\sim}9.4$, 7.91; water temperature $6.1{\sim}34.8^{\circ}C,\;23.88^{\circ}C$; electrical conductivity (from St. A to G) $1.575{\times}10^2{\sim}30.50{\times}10^2{\mu}{\mho}/cm,\;6.57{\times}10^2{\mu}{\mho}/cm$; chloride ion $23.5{\sim}14,300mg/l$, 770.0mg/l; nitrite-nitrogen $0.007{\sim}0.110mg/l$, 0.053mg/l; nitrate-nitrogen $0.001{\sim}1.638mg/l$, 0.649 mg/l; ammonia-nitrogen $0.017{\sim}4.200mg/l$, 0.497mg/l; phosphate-phoshorus $0.011{\sim}0.281mg/l$, 0.086mg/l; and silicate-silicious $2.4{\sim}6.5mg/l$, 4.43mg/l. Electrical conductivity and chloride ion of the station F(Chomanpo) were $2.676{\times}10^2{\mu}{\Omega}cm$ and 123.99mg/l which were lower than those of others. Among the analyzed nutrients, silicate-silicious concentration was the highest through all the samples. The bacterial density of the samples ranged $36{\sim}110,000/100ml$ for total coliform, $15{\sim}46,000/100ml$ for fecal coliform and $3.6{\sim}15,000/100ml$ for fecal streptococcus. The range and the mean of the TC/FC ratio were $3.0{\sim}9.6$, 5.51 and those of the FC/FS ratio were $1.1{\sim}9.2$, 6.19, respectively. On the other hand, fecal coliform was not detected in about $78\%$ of the water samples examined. Composition of coliform was $52\%$ Escherichia coli group, $3\%$ Citrobacter freundii group, $13\%$ Enterobacter aerogenes group and $31\%$ others.

• Applied Biological Chemistry
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• v.14 no.1
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• pp.9-18
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• 1971

In order to obtain basic information on the production of single cell protein from petroleum, more than 400 yeast strains were isolated from various soil samples in Korea utilizing petroleum hydrocarbon as the sole carbon source. A yeast strain showing the highest cell yield among the isolated strains was selected and identified. The optimal culture condition was searched in the flasks shaken throughout the procedure. And the growing characteristics for the selected yeast strain and chemical analysis of the yeast cell component were carried out. The results obtained were as follows: 1. The selected yeast strain was identified as Candida curvata and we named it Candida curvata-SNU 70. 2. The composition of the medium proposed for the present yeast strain is: Light Gas Oil 30ml, Urea 400mg, Ammonium sulfate 100mg, Potasium phosphate (monobasic) 670mg, Sodium phosphate (dibasic) 330mg, Magnesium sulfate 500mg, Calcium carbonate 3g, Yeast extract 50mg, Tween 20 0.05ml, Tap water 1,000ml. 3. Other culture conditions employed for the yeast were pH 5.5-7.0, temp. $30^{\circ}C$ under an affluent aerobic state. 4. Addition of light gas oil in portions to the culture media as the growth proceeded was more effective, especially in the cultivation on the higher oil concentration media. 5. Studies on the propagation of the yeast cells in the light gas oil medium revealed that the yeast has the lag phase lasted 16 hours and the logarithmic growth phase covered 16 to 28 hours. The specific growth rate was about $0.22\;hr^{-1}$ and doubling time was 3.2 hrs. during the logarithmic growth phase. 6. Under the cultural condition employed, the cell yield against the amount of light gas oil (wt%) was 16.1% and the protein content of the dried yeast cells was 48.4%.