• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.185-188
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• 2003

The possible inhibitory effect of wood hydrolyzate in lactic acid fermentation was partially decreased by adaptation of Enterococcus faecalis RKY1 to wood hydrolyzate-based medium. The strain RKY1 grown on wood hydrolyzate-based medium was tolerant to wood hydrolyzate medium with fermentation efficiency being improved to approximately 20% higher than that obtained with the strain RKY1 grown on glucose-based medium.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.1
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• pp.52-60
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• 2004

The optimized in vitro culture system was investigated for improvement of regeneration efficiencies by observing the responses of scutella-derived callus of Korean rice (Oryza sativa L.). Large variations of callus induction (43.9-93.9%) and shoot regeneration (0-88.7%) were observed among the rice cultivars depending on medium. However, shoot regeneration was significantly improved by selected utilization of basal medium, growth regulators, and carbon sources. N6 basal medium was more efficient for embryogenic callus induction than MS or LS basal medium, while MS was superior to N6 for shoot regeneration. The calli of highly regenerative cultivars grew faster and showed higher rates of green tissue formation (GT) and shoot regeneration (SR) and lower rate of callus browning (CB) than those of recalcitrant cultivars. Although a higher level of kinetin stimulated the GT and SR in highly regenerative cultivars, $10\textrm{mgL}^{-1}$ kinetin generally suppressed the GT and SR, while CB was accelerated compared to $2\textrm{mgL}^{-1}$ kinetin. Additional benefits of sorbitol combined with maltose (or sucrose) under $5\textrm{mgL}^{-1}$ kinetin were certainly confirmed on regeneration efficiencies compared to sucrose alone as carbon source and osmotic regulator. This combination showed high rate of GT and SR with multiple shoots while low rate of CB. With MSRK5SM-Pr medium ($5\textrm{mgL}^{-1}$ kinetin, 3% sorbitol, 2% maltose, $500\textrm{mgL}^{-1}$ proline), the regeneration efficiencies of total 17 out of 24 cultivars were practically improved 160% on average compared to MSRK2S ($2\textrm{mgL}^{-1}$ kinetin, 3% sucrose) control medium. Especially, the medium was most effective to the cultivars showing a medium level of regenerability such as Daesanbyeo and Dongjinbyeo and Suwon477, enhancing efficiencies more than 300-600% compared to MSRK2S medium.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.153-156
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• 2003

The MRS medium is widely used as an optimized medium for the growth of Lactobacillus spp. and also used for the growth of Leuconostoc spp. Leuconostoc mesenteroides shows quite different physicochemical properties compared to Lactobacilli spp. and it is one of the major strain of kimchi fermenting microorganisms with its usefulness in our traditional foods and availability in biotechnology in the future, specifically tailor-made medium is necessary for the growth of Leuconostoc mesenteroides. Sequential experimental designs (Plackett-Burman, fractional factorial, steepest ascent, central composite design and response surface methodology) were introduced to optimize and improve the Leuconostoc medium. Fifteen medium ingredients were investigated and fructose, sodium acetate and ammonium citrate were determined to give a critical and positive effect for cell-growth. The yield of biomass using the optimal medium was improved more than that of the MRS medium and the result of fed-batch culture showed the capability of the improvement in cell mass similar to the E.coli system.

• ALGAE
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• v.37 no.2
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• pp.175-183
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• 2022

Polar microorganisms produce physiologically active substances to adapt to harsh environments, and these substances can be used as biomedical compounds. The green microalga Micractinium variabile KSF0031, which was isolated from Antarctica, produced phytol, a natural antimicrobial agent. Furthermore, several polyunsaturated fatty acids (PUFAs), including omega-3, exhibit antioxidant properties. Here statistical methods (Plackett-Burman design and Box-Behnken design) were used to optimize the culture medium of KSF0031 to improve biomass production, and K₂HPO₄, MgSO₄·7H ₂O, and ammonium ferric citrate green (AFCg) were selected as significant components of the culture medium. Changes in the concentration of K₂HPO₄ and MgSO₄·7H ₂O as positive factors and AFCg as a negative factor affected cell growth to a remarkable degree. The biomass production in a 100 L culture using the optimized medium for 24 d at 18℃ was improved by 37.5% compared to that obtained using the original BG-11 medium. The quantities of PUFAs and phytol obtained were 13 mg g^-1 dry cell weight (DCW) and 10.98 mg g^-1 DCW, which represent improved yields of 11.70% and 48.78%, respectively. The results of this study could contribute to an improved production of phytol and fatty acids from Antarctic microalgae in the biomedical industry.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.293-296
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• 2002

Hyperosmotic pressure increased specific antibody productivity ($q_{Ab}$) of recombinant CHO cells (SH2-0.32) while it depressed cell growth. Thus, the use of hyperosmolar medium did not increase the maximum antibody concentration substantially. To overcome this drawback, the feasibility of biphasic culture strategy was investigated. In the biphasic culture, cells were first cultivated in the standard medium with physiological osmolality(294 mOsm/kg) for cell growth. When cells reached the late exponential phase of growth, the spent standard medium was replaced with the fresh hyperosmolar medium (522 mOsm/kg) for antibody production. The ($q_{Ab}$) in growth phase with the standard medium was 2.1 ${\mu}g/10^6cell/day$ while the ($q_{Ab}$) in antibody production phase with the hyperosmolar medium (522 mOsm/kg) was 11.1 ${\mu}g/10^6cell/day$. Northern blot analysis showed a positive relationship between the relative contenet of Ig mRNA and ($q_{Ab}$), indicating that transcriptional regulation was involved in the response of rCHO cells to hyperosmotic pressure. Due to the enhanced ($q_{Ab}$) and increased cell concentration in biphasic culture, the maximum antibody concentration obtained in biphasic culture with 522 mOsm/kg medium exchange was 161% higher than that obtained in batch culture with the standard medium. Taken together, simple biphasic culture strategy based on hyperosmotic culture for improved foreign protein production from rCHO cells is effective in improving antibody production of rCHO cells.

• KSBB Journal
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• v.22 no.4
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• pp.185-190
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• 2007

Productivity of secreted recombinant protein depends largely on its stability in the extracellular environment with protease. Most hGM-CSF produced by transgenic tobacco cell cultures and secreted to the medium was confirmed to be rapidly degraded by protease in medium. To increase the productivity, therefore, various protein stabilizers such as gelling agents such as carrageenan and alginate, polymers, polyols, and amino acids have been tested. The stability of hGM-CSF in spent medium without cells was improved by the presence of gelling agents. However, the reason for the enhanced production by the addition of gelling agents may be due to the increased expression level and permeability rather than stability. The addition of DMSO inhibited the cell growth, but improved specific yield. The others were not effective for stability as well as hGM-CSF production.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.632-642
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• 2017

This paper presents an improved approach towards reducing the switching loss of insulated gate bipolar transistors (IGBTs) for a medium-capacity-class power conditioning system (PCS). In order to improve the switching performance, the switching operation is analyzed, and based on this analysis, an improved switching method that reduces the switching time and switching loss is proposed. Compared to a conventional gate drive scheme, the switching loss, switching time, and delay are improved in the proposed gate driving method. The performance of the proposed gate driving method is verified through several experiments.

• Korean Management Science Review
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• v.30 no.3
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• pp.71-79
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• 2013

This paper investigates and selects the areas that need to be improved in R&D and production management of small and medium size companies. The study on the capability of R&D and production management shows that the areas for evaluating of the R&D and production management levels are composed of 8 elements : R&D resource, R&D support and experience, long-term operations strategy, intermediate range planning, short-term planning, subcontractor management, logistics and inventory management, and quality management. The investigation of the gap between the importance of the areas and the capability of SMEs shows that the most important things are to consolidate supply chain, to improve product and process competitiveness using quality improvement, and to enhance production management through sophisticated short-term planning. The detailed analysis also shows that the areas that need to be improved depend on the size and sales of the company.

• Polymer(Korea)
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• v.34 no.6
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• pp.522-526
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• 2010

Bacterial cellulose is produced by the bacterium Gluconacetobacter xylinus, which forms a nanofibrous pellicle in its culture medium. We studied properties of the bacterial cellulose such as crystallinity, viscosity, morphology, and mechanical properties according to the carbon source. Static cultures of Gluconacetobacter sp. V6 were performed in three kinds of media: standard Hestrin-Schramm medium, and modified medium with either glycerol or molasses as carbon sources. Cell growth and cellulose yield were increased in the glycerol and molasses media. The culture in the glycerol medium improved the physical properties of cellulose such as crystallinity, intrinsic viscosity, and breaking stress. However, the culture in the molasses medium decreased crystallinity, crystallite size, and intrinsic viscosity of cellulose. In summary, the cellulose yield was remarkably improved in the molasses medium, but with inferior structural properties.

• Atmosphere
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• v.34 no.1
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• pp.23-34
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• 2024

The Korea Meteorological Administration has improved medium-range weather forecasts by implementing post-processing methods to minimize numerical model errors. In this study, we employ a statistical correction technique known as the minimum continuous ranked probability score (CRPS) to refine medium-range forecast guidance. This technique quantifies the similarity between the predicted values and the observed cumulative distribution function of the Unified Model Ensemble Prediction System for Global (UM EPSG). We evaluated the performance of the medium-range forecast guidance for surface air temperature and relative humidity, noting significant enhancements in seasonal bias and root mean squared error compared to observations. Notably, compared to the existing the medium-range forecast guidance, temperature forecasts exhibit 17.5% improvement in summer and 21.5% improvement in winter. Humidity forecasts also show 12% improvement in summer and 23% improvement in winter. The results indicate that utilizing the minimum CRPS for medium-range forecast guidance provide more reliable and improved performance than UM EPSG.