• Applied Biological Chemistry
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• v.30 no.1
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• pp.77-87
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• 1987

The mutant with high productivity, X. malvacearum SNUF 560-6, was acquired from the X. malvacearum SNUF 560 with low productivity by UV-light irradiation. It was preserved is lyophilized stock culture and it was transferred to PDA slant to maintain viability fortnightly. Fermentations were started by retransfering to MY agar slant from PDA stok culture. The experiments for optimal xanthan gum production were studied in a chemically defined medium. Of the carbon and nitrogen sources tested, 0.4% sucrose medium and 10mM glutamic acid medium yielded the highest xanthan gun production respectively. The addition of 10g/l succinic acid stimulated xanthan gum production. Also 65mM $PO_4\;^{-3}\;(12.6g/l\;KH_2PO_4)$ was effective on xanthan gum production. Finally, medium 1 and medium 2 which have high xanthan gum production potencies were achieved in this stud. The components of medium 1 and medium 2 were as follows: Medium 1 : sucrose 40g/l glutamate 10mM $PO_4\;^{-3}\;54mM\;(KH_2PO_4\;12.65g/l)$ Citrate 2g/l $MgSO_4{\cdot}7H_2O\;0.2g/l$ $H_3BO_3\;0.005/l$ ZnO 0.006/l $FeCl_2{\cdot}6H_2O\;0.0024g/l$ $CaCO_3\;0.02g/l$ Medium 2 : $Sucrose\;40g/l\;(NH_4)_2SO_4\;2g/l$ $PO_4\;^{-3}\;65mM\;(KH_2PO_4\;12.65g/l)$ Succinate 10g/l $MgSO_4{\cdot}7H_2O\;0.02g/l$ $H_3BO_3\;0.06g/l$ ZnO 0.006g/l $FeCl_2{\cdot}6H_2O\;0.0024g/l$ $CaCO_3\;0.02g/l$.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.89-89
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• 2019

Several studies report the anticancer effect of Glycyrrhiza glabra (G. glabra), Glycyrrhiza uralensis (G. uralensis) and their compounds. However, the anticancer effect of Glycyrrhiza cultivar roots are limited. In this study, we compared the anticancer effect of Glycyrrhiza cultivar (Wongam and Shinwongam) extracts with G. glabra and G. uralensis extracts in breast cancer cell lines. Freeze dried Glycyrrhiza root extracts were dissolved in cell culture media at 2 mg/mL and filtered by $0.2{\mu}m$ filter. Glycyrrhiza root extracts were serially diluted at the concentrations of $10{\mu}g/mL$, $100{\mu}g/mL$, $200{\mu}g/mL$, $400{\mu}g/mL$, $800{\mu}g/mL$, $1000{\mu}g/mL$ and $2000{\mu}g/mL$. MCF-7 and MDA-MB-231 breast cancer cells were treated with different concentrations of Glycyrrhiza root extracts and the cell viability was measured using MTT assay. In MCF-7 cells, G. glabra showed no significant difference with Wongam and showed significant difference with Shinwongam at $1000{\mu}g/mL$ (G. glabra 101.2% and Shinwongam 82.68%) and $2000{\mu}g/mL$ (G. glabra 83.07% and Shinwongam 54.05%). G. uralensis showed significant difference with Wongam at $2000{\mu}g/mL$ (G. uralensis 66.48% and Wongam 95.02%) and showed no significant difference with Shinwongam. In MDA-MB-231 cells, G. glabra showed no significant difference with both Wongam and Shinwongam. G. uralensis showed significant difference with Wongam at $2000{\mu}g/mL$ (G. uralensis 72.59% and Wongam 93.47%) and showed no significant difference with Shinwongam. In conclusion, the current study demonstrated that G, glabra and G. uralensis compared with Wongam, and Shinwongam at low concentrations ($10{\mu}g/mL{\sim}800{\mu}g/mL$) display similar cytotoxic potency.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.4
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• pp.41-49
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• 2023

This study examined the effect of input substrate concentration on hydrogen production of microbial electrolysis cells. To compare the performance of MEC according to the input substrate concentration, six laboratory-scale MEC reactors were operated by sequentially increasing the input substrate concentration from 2 g/L of sodium acetate, to 4 g/L, and 6 g/L. The current density, hydrogen production, and SCOD removal rate were analyzed, and energy efficiency and cathodic hydrogen recovery were calculated to compare the performance of MEC. The maximum volumetric current density was obtained at 4 g/L condition (76.3 A/m³) and it decreased to 19.0 A/m³, when the input concentration was increased to 6 g/L, which was a 75% decrease compared to the 4 g/L input condition. Maximum hydrogen production was obtained also at 4 g/L condition (47.3 ± 16.8 mL), but maximum hydrogen yield was obtained at 2 g/L input condition (1.1 L H₂/g COD_in). Energy efficiencies were also highest in 2 g/L condition; the lowest result was observed at 6 g/L condition. Maximum electrical energy efficiency was 76.4%, and the maximum overall energy efficiency was 39.7% at 2 g/L condition. However, when the substrate concentration increased to 6 g/L, the performance was drastically decreased. Cathodic hydrogen recovery also showed a similar tendency with energy efficiency, with the lowest concentration condition showing the best performance. It can be concluded that operating at low input substrate concentration might be better when considering not only hydrogen yield but also energy efficiency.

• Bulletin of the Korean Mathematical Society
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• v.32 no.2
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• pp.221-231
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• 1995

Let $Z_1, Z_2, \ldots, Z_l$ be random set functions or intergrals. Then it is possible to discuss their products. In the case of random integrals, $Z_i$ is a random set function indexed y a family, $G_i$ say, of real valued functions g on $S_i$ for which the integrals $Z_i(g) = \smallint gdZ_i$ are well defined. If $g_i = \in g_i (i = 1, 2, \ldots, l) and g_1 \otimes \cdots \otimes g_l$ denotes the tensor product $g(s) = g_1(s_1)g_2(s_2) \cdots g_l(s_l) for s = (s_1, s_2, \ldots, s_l) and s_i \in S_i$, then we can defined $Z(g) = (Z_1 \times Z_2 \times \cdots \times Z_l)(g) = Z_1(g_1)Z_2(g_2) \cdots Z_l(g_l)$.

• Journal of Life Science
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• v.21 no.3
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• pp.335-340
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• 2011

Glucose and xylose are the most abundant materials in nature which can be used to produce ethanol by yeast fermentation. Three combinations of cultivation with glucose and xylose were carried out; separated, co-culture, and sequential fermentation with Saccharomyces cerevisiae and Pichia stipitis. In the separated fermentation, S. cerevisiae fermented glucose to produce 14.5 g/l ethanol from 29.4 g/l glucose but hardly used xylose. However, P. stipitis utilized not only glucose but also xylose to produce ethanol 11.9 g/l and 11.6 g/l from 29.4 g/l glucose and 29.0 g/l xylose, respectively. In the mixture of glucose and xylose, P. stipitis fermented both sugars, producing 21.1 g/l ethanol while S. cerevisiae fermented only glucose, producing 13.4 g/l ethanol. In the co-culture and sequential fermentation, the co-culture showed more efficient ethanol productivity with 18.6 g/l ethanol than the sequential fermentation with 12.4 g/l ethanol. To investigate the effect of nutrients in the growth of microorganisms and ethanol production, yeast nitrogen base (YNB) was used in the sequential fermentation with S. cerevisiae and P. stipitis. YNB supplemented some nutrients which S. cerevisiae used up in the broth and the culture showed increased growth rate, increased consumption of xylose, and increased ethanol productivity producing 22.5 g/l ethanol from 54.6 g/l sugar with a yield of 0.41 g/g.

• Korean Journal of Environmental Biology
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• v.21 no.1
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• pp.72-76
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• 2003

We investigated the effects of molting-hormone insecticide tebufenozide on fourth larvae of the midge C. flaviplumuon in growth development from fourth-instar to adult. Fourth-instar larvae were exposed test concentrations were chosen control, 10 $\mu\textrm{g}$$L^{-1}$, 30 $\mu\textrm{g}$$L^{-1}$, 60 $\mu\textrm{g}$$L^{-1}$ and 100$\mu\textrm{g}$$L^{-1}$. In control and 10 $\mu\textrm{g}$$L^{-1}$, 10~20% individuals succeed adults while low emergence rates were observed surplus 30 $\mu\textrm{g}$$L^{-1}$. Death larvae appeared a various day along the concentration. We observed the converged day: control, 10 $\mu\textrm{g}$$L^{-1}$, 30 $\mu\textrm{g}$$L^{-1}$ and 60~100 $\mu\textrm{g}$$L^{-1}$ were day 4 to day 18, day 13 to day 16, day 9 to day 17 and day 9 to day 15, respectively. Therefore we concerned a tendency that exposure concentration was high, death period was short. Also, due to molting hormone disruption, development of midge was postponed relatively low concentration such as 10 $\mu\textrm{g}$$L^{-1}$. The converged days of pupa stage revealed control, 10 $\mu\textrm{g}$$L^{-1}$, 30 $\mu\textrm{g}$$L^{-1}$ and 60~100$\mu\textrm{g}$$L^{-1}$ were day 11~15, day 16~20, day 9~15 and day 5~9, respectively. About 10% individuals grow up the pupa-stage in 60~100 $\mu\textrm{g}$$L^{-1}$ condition. Sex ratio of the emerged adults was not different in this study. Death pupae frequently appeared in day 13~16 in control, day 6~23 in 10 $\mu\textrm{g}$$L^{-1}$, day 13~16 in 30 $\mu\textrm{g}$$L^{-1}$ and day 6~16 in 60~100 $\mu\textrm{g}$$L^{-1}$.

• Journal of Environmental Health Sciences
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• v.12 no.1
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• pp.69-78
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• 1986

In order to determine the content levels of trace metals in cow's milk, 79 market milk samples were collected from markets in major cities of Korea from July to August, 1985 and analyzed for content levels of Cu, Fe, Zn, Mn, Pb, Cd. The Results were as follows Cu, average 43.5 $\mu$g/l range 14 ~ 172.7 $\mu$g/l Fe, average 398.4 $\mu$g/l range 35 ~ 1,873 $\mu$g/l Zn, average 2.917 mg/l range 1.233 ~ 7.46 mg/l Mn, average 26.74 $\mu$g/l range 7.6 ~ 102 $\mu$g/l Pb, average 33.9 $\mu$g/l range N.D. ~ 105 $\mu$g/l Cd, average 1.73 $\mu$g/l range N.D. ~ 5.4 $\mu$g/l

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.268-272
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• 2003

Experiments were carried out to investigate the selection of industrial medium and optimization of fermentation process for the production of erythritol by Candida magnoliae SR101. In the batch fermentation, light steep water(LSW) was the best nitrogen source for the industrial production of erythritol. For the optimization of culture condition, the batch culture was performed. When the concentration of LSW was 65 mL/L in the defined medium containing 250 g/L of glucose, 44% of erythritol yield with 110 g/L of erythritol concentration and 0.66 g/L-hr of productivity, respectively were obtained. Two-stage fed-batch culture was performed to improve the volumetric productivity of erythritol. High density cell culture in the growth stage was performed by batch type with 100 g/L glucose and 500 mL/L LSW concentration, respectively. The cell yield was 0.72 g-cell/g-glucose. Productivity of erythritol was increased and concentration of organic acids such as gluconic acid and acetic acid were decreased when initial pH of 6.5 controlled by 28% ammonia water For increasing yield of erythritol, glucose concentration in the production stage was tested. 37% of total erythritol yield with 186 g/L of erythritol concentration and 1.66 g/L-hr of erythritol productivity were obtained when 820 g of glucose powder was directly added for making up 450 g/L of glucose at production stage.

• KSBB Journal
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• v.5 no.2
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• pp.167-173
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• 1990

This study is to investigate for obtaining the operating conditions of continuous vinegar production using fluidized bed reactor by Acetobacter aceti cell immobilized in Ca-alginate gel. The optimum conditions obtaining by batch fermentation using fluidized bed reactor were as follows; The fermentation temperature and aeration rate were 3$0^{\circ}C$ and 1.0VVM and the initial concentration of ethanol and acetic acid in medium were 33g/l and 27g/l respectively. The amount of bead used was 25%(w/v). The overall acetic acid productivities of batch fermentations by free cell and immobilized cell were 0.31g/l-hr and 0.48g/l-hr, respectively, at the final acetic acid concentration of 50g/l. In the continuous vinegar production using fluidized bed reactor by immobilized cell under optimum conditions, it was possible to produce 23g/l acetic acid continuously up to 90 days with maximum acetic acid productivity of 2.76g/l-hr at dilution rate 0.12hr-1.

• KSBB Journal
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• v.22 no.1
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• pp.1-6
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• 2007

The optimum liquid culture conditions were investigated for cell growth and polysaccharide production from liquid culture of Lentinus edodes. In flask culture, the optimal medium compositions for the polysaccharide production contained glucose 60 g/L, yeast extract 10 g/L, $KH_2PO_4$ 2.0 g/L, and $MgSO_4{\cdot}7H_2O$ 1.0 g/L. The maximum mycelial growth and polysaccharide production were 11.01 g/L and 1.64 g/L, respectively. In bioreactor, through the variation of aeration in order to increase mycelial growth and polysaccharide production, the maximum mycelial growth and polysaccharide production were 55.9 g/L at 8th day and 7.34 g/L at 7th day of cultivation with 1.5 vvm, respectively.