• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.380-383
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• 2000

The effect of on the cell growth, the elaboration of pullulan, the morphology and were the effect of on the molecular weight of pullulan were investigated. A. pullulans showed maximum pullulan production when initial pH 6.5 was 11.98 g/l in shake-flask culture. In batch culture, the maximum pullulan production of 15.16 g/l was obtained at an aeration rate of 0.5 vvm. The mixture of yeast-like form and mycelial form of cells was found at the constant pH 4.5, at which condition, the elaboration of pullulan was high, about 13.31 g/l. However, pullulan with its higher molecular weight (>1,000,000) was produced at the constant pH 6.5.

• Journal of the Korean Mathematical Society
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• v.56 no.4
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• pp.869-915
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• 2019

Let H be a Krull monoid with class group G such that every class contains a prime divisor. Then every nonunit $a{\in}H$ can be written as a finite product of irreducible elements. If $a=u_1{\cdot}\;{\ldots}\;{\cdot}u_k$ with irreducibles $u_1,{\ldots},u_k{\in}H$, then k is called the length of the factorization and the set L(a) of all possible k is the set of lengths of a. It is well-known that the system ${\mathcal{L}}(H)=\{{\mathcal{L}}(a){\mid}a{\in}H\}$ depends only on the class group G. We study the inverse question asking whether the system ${\mathcal{L}}(H)$ is characteristic for the class group. Let H' be a further Krull monoid with class group G' such that every class contains a prime divisor and suppose that ${\mathcal{L}}(H)={\mathcal{L}}(H^{\prime})$. We show that, if one of the groups G and G' is finite and has rank at most two, then G and G' are isomorphic (apart from two well-known exceptions).

• Proceedings of the Korean Society of Crop Science Conference
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• 2001.05a
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• pp.142-143
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• 2001

• Horticultural Science & Technology
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• v.16 no.2
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• pp.239-241
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• 1998

The experiments were carried out to improve culture efficiency of rhizome and mericlone propagation through settlement of problems occurring during culture period of temperate Cymbidium species. Shooting efficiency from rhizome of C. forrestii 'Nokwoon' was improved, when cultured in $H_3P_4$ medium (Hyponex 3+peptone 4g/L) supplemented with 170mg/L $NaH_2PO_4{\cdot}H_2O$ and 0.4mg/L Thiamin e HCl, but the other varieties were not influenced to shooting efficiency by additives. Medium in which rhizome of C. nishiuchianum 'Hodukjiwha' was cultured became less browned in $H_3P_4$ medium added with 150mg/L PVP, but the other treatments of antioxidants was failed to prevent the medium browning. Re-formation of rhizome from young shoots of C. forrestii 'Sojub', 5.5cm in length occured in $H_3P_4$ enriched with 2.0 mg/L NAA and 1.0 mg/L BA under darkness, but axillary buds were elongated in the medium with 1.0 mg/L NAA and 3.0 mg/L BA under light condition. On the other hand, rhizomes from young shoot of C. forrestii 'Seosinmae' and 'Songmae', 5.5cm and 2.5cm in length respectively were reformed in 2.0 mg/L NAA and 5.0mg/L kinetin under darkness, but multishoot from young shoot were emerged in 2.0mg/L NAA and 3.0mg/L BA.

• Proceedings of the Korean Society of Computational and Applied Mathematics Conference
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• 2003.09a
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• pp.4.1-4
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• 2003

Given operators X and Y acting on a Hilbert space H, an interpolating operator is a bounded operator A such that AX= Y. An interpolating operator for n-operators satisfies the equation AXi= Yi, for i = 1,2,...,n, In this article, we showed the following : Let H be a Hilbert space and let L be a subspace lattice on H. Let X and Y be operators acting on H. Assume that rangeX is dense in H. Then the following statements are equivalent : (1) There exists an operator A in AlgL such that AX = Y, A$\^$*/=A and every E in L reduces A. (2) sup｛(equation omitted) : n $\in$ N f$\sub$I/ $\in$ H and E$\sub$I/ $\in$ L｝<$\infty$ and = for all E in L and all f, g in H.

• Food Science of Animal Resources
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• v.30 no.5
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• pp.717-721
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• 2010

The objective of this study was to evaluate the inhibition of Listeria monocytogenes growth by oleanolic acid under sublethal stresses of NaCl and pH. L. monocytogenes ATCC15313 (6 log CFU/mL) was inoculated in microplate wells containing brain heart infusion (BHI) broth supplemented with oleanolic acid in various amounts (0, 0.25, 0.5, 1.0, 1.5, 2.0, and $4.0\;{\mu}g/mL$), and different pHs (5 and 7) and NaCl concentrations (0, 3, and 6%), followed by incubation under accelerated storage condition ($37^{\circ}C$, 48 h). The optical density (OD) of the samples was measured at 0, 6, 12, 24, and 48 h at 600 nm. After the lag phase duration was observed at the early stage of incubation, the OD values of L. monocytogenes significantly increased (p<0.05) in BHI broth formulated with 0 and 3% of NaCl during accelerated storage at pH 5 and 7. However, the growth of L. monocytogenes in 6% NaCl and at less than $0.5\;{\mu}g/mL$ of oleanolic acid had no growth at pH 5 and only gradual growth at pH 7. Moreover, L. monocytogenes generally had lower OD values as the concentrations of oleanolic acid increased. As expected, the OD values of L. monocytogenes were generally higher (p<0.05) at pH 7 than at pH 5. These results indicate that oleanolic acid should be useful in inhibiting the growth of L. monocytogenes.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.4
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• pp.326-329
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• 2004

Corynebacterium acetoacidophilum RYU3161 was cultivated in a L-histidine-limited fed-batch culture. To investigate the effect of cell growth on the L-proline production, 5 L fed-batch culture was performed using an exponential feeding rate to obtain the specific growth rates $(\mu)$ of 0.04, 0.06, 0.08, and 0.1 $h_1$. The results show that the highest production of L-proline was obtained at $\mu$ = 0.04 $h_1$. The specific L-proline production rate $(Q_p)$ increased pro-portionally as a function of the specific growth rate, but decreased after it revealed the maxi-mum value at $\mu$ = 0.08 $h_1$. Thus, the highest productivity of L-proline was 1.66 g $L^-^1 h^-^1$ at $\mu$ = 0.08 $h_1$. The results show that the production of L-proline in C. acetoacidophilum RYU3161 has mixed growth-associated characteristics.

• Journal of environmental and Sanitary engineering
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• v.12 no.1
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• pp.85-95
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• 1997

Behavior of Listeria monocytogenes in Skim milk during fermentation by Lactobacillus bulgaricus YI-2 and Streptococcus lactis FYI-1 were determined. Autoclaved skim milk was inoculated with ca. 10$^{3}$ L. monocytogenes (Strain LM91-1 or LM 96-2) cells/ml, and with 5.0, 1.0, 0.5 or 0.1% of a milk culture of either L. bulgaricus TI-2 or S. lactis FYI-1. Skim milk containing ca. 10$^{3}$ L. monocytogenes was incubated at 37 or 42$\circ $C for 15 h with L. bulgaricus YI-2, and at 21 or 30$\circ $C for 15 h with S. lactis FYI-1. Cultured skim milks were stored at 4$\circ $C in the refrigerater. Samples were plated on Oxford Agar with oxford antimicrobic supplement to enumerate L. monocytogenes and on either modified MRS agar to enumerate lactic acid bacteria. L. monocytogenes survived the 15-h fermentation with S. lactis FYI-1 in all combinations of level of inoculum and temperature of incubation, but inhibition of growth ranged from 94 to 100%. When incubated with over the 1.0% of L. bulgaricus, L. monocytogenes inhibited or disappeared in fermented skim milk from 9 h after incubation. Especially, incubation at 42$\circ $C with 5.0% L. bulgaricus YI-2 as inoculum appeared to be the most effective inhibitory combination for strain LM 91-1, causing 100% inhibition in growth based on maximum papulation attained. In most instances of incubated with L. bulgaricus YI-2, growth of the pathogene appeared to be completely inhibited when the pH dropped below 4.38.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.3
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• pp.399-405
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• 2011

In a desalination technology using RO membranes, chemical cleaning makes damage for membrane surface and membrane life be shortened. In this research cleaning technology using direct osmosis (DO) was introduced to apply it under the condition of high pH and high concentration of feed. When the high concentration of feed is injected to the concentrate side after release of operating pressure, then backward flow occurred from treated water toward concentrated for osmotic pressure. This flow reduces fouling on the membrane surface. Namely, flux of DO was monitored under pH 3, 5, 10 and 12 conditions at feed concentrations of NaCl 40,000 mg/L, 120,000 mg/L and 160,000 mg/L. As a result, DO flux in pH 12 increased about 21% than pH 3. DO cleaning was performed under the concentrate NaCl 160,000 mg/L of pH 12 during 20 minutes. Three kinds of synthetic feed water were used as concentrates. They consisted of organic, inorganic and seawater; chemicals of SiO2 (200 mg/L), humic acid (50 mg/L) sodium alginate (50 mg/L) and seawater. As a result, fluxes were recovered to 17% in organic fouling, 15% in inorganic fouling and 14% of seawater fouling after cleaning using DO under the condition of concentrate NaCl 160,000 mg/L of pH 12.

• KSBB Journal
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• v.17 no.6
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• pp.509-514
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• 2002

Experiments were carried out to optimize the fermentation conditions for the production of erythritol by salt-tolerant mutant, Candida magnoliae M26. The optimum conditions of erythritol production showed a 1.0 vvm aeration and 500 rpm agitation at 28$\^{C}$ with an initial medium pH of 7.0. The pH control during the fermentation did not improve the erythritol yield and productivity. The maximum erythritol concentration of 143.3 g/L was obtained with 57% yield and 0.70 g/L-h productivity from 250 g/L of glucose and 5 g/L of yeast extract under an optimum fermentation conditions. The medium containing 0.5 M KCl or 0.5 M NaCl enhanced the production of erythritol and glycerol. However, glycerol production increased and erythrtiol production decreased by increasing the concentration of NaCl or KCl.