• Microbiology and Biotechnology Letters
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• v.51 no.1
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• pp.59-68
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• 2023

Xylanase is an industrially relevant enzyme used for the production of xylobiose and xylose. Various methods are used to enhance the microbial yield of xylanase. In the present study, co-culturing of Bacillus subtilis and Bacillus pumilus were investigated using submerged fermentation for xylanase production, which was markedly increased when sal, sagwan, newspaper, wheat bran, and xylan were used as single carbon sources. Maximum xylanase production was reported after 5 days of incubation in optimized media at pH 7.0 and 37℃, resulting in 2.69 ± 0.25 µmol/min by coculture. The 1:1 ratio of sal and sagwan in optimized production media was shown to be suitable for xylanase synthesis in submerged fermentation (SMF). In comparison to mono-culture using B. pumilus and B. subtilis, co-culturing resulted in an overall 3.8-fold and 2.15-fold increase in xylanase production, respectively.

• Food Science and Biotechnology
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• v.16 no.1
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• pp.159-162
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• 2007

Optimization of the fermentation medium for phenylethyl alcohol (PEA) production by Pichia anomala SKM-T was performed. The carbon source (glucose), nitrogen source (L-phenylalanine), and initial pH value were independent variables of the optimized medium. The central composite rotatable design was used for the experimental design and the analysis of the results. The optimum medium composition for the maximal production (621.27 mg/L) of PEA was found to be an initial pH of 5.03, and concentrations of L-phenylalanine at 6.53 and glucose at 6.11 g/L (w/v). This experimental finding is in close agreement with the model prediction (702.79 mg/L; desirability 0.884) with an 11.6% difference.

• Journal of Microbiology
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• v.43 no.1
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• pp.38-43
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• 2005

Lactic acid production parameter optimization using Lactobacillus amylovorus NRRL B-4542 was performed using the design of experiments (DOE) available in the form of an orthogonal array and a software for automatic design and analysis of the experiments, both based on Taguchi protocol. Optimal levels of physical parameters and key media components namely temperature, pH, inoculum size, moisture, yeast extract, $MgSO_4{\cdot}7H_20$, Tween 80, and corn steep liquor (CSL) were determined. Among the physical parameters, temperature contributed higher influence, and among media components, yeast extract, $MgSO_4{\cdot}7H_20$, and Tween 80 played important roles in the conversion of starch to lactic acid. The expected yield of lactic acid under these optimal conditions was 95.80% and the actual yield at optimum conditions was 93.50%.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1993.04a
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• pp.109-118
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• 1993

This paper describes the management of knowledge base and optimization models using knowledge-assisted optimization model formulation system UNIK-OPT (UNIfied Knowledge-OPTimization). We will illustrate UNIK-OPT with the case of production scheduling in refinery.

• Journal of Microbiology and Biotechnology
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• v.23 no.12
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• pp.1757-1764
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• 2013

Trichoderma harzianum ZF-2 producing laccase was isolated from decaying samples from Shandong, China, and showed dye decolorization activities. The objective of this study was to optimize its culture conditions using a statistical analysis of its laccase production. The interactions between different fermentation parameters for laccase production were characterized using a Plackett-Burman design and the response surface methodology. The different media components were initially optimized using the conventional one-factor-at-a-time method and an orthogonal test design, and a Plackett-Burman experiment was then performed to evaluate the effects on laccase production. Wheat straw powder, soybean meal, and $CuSO_4$ were all found to have a significant influence on laccase production, and the optimal concentrations of these three factors were then sequentially investigated using the response surface methodology with a central composite design. The resulting optimal medium components for laccase production were determined as follows: wheat straw powder 7.63 g/l, soybean meal 23.07 g/l, $(NH_4)_2SO_4$ 1 g/l, $CuSO_4$ 0.51 g/l, Tween-20 1 g/l, $MgSO_4$ 1 g/l, and $KH_2PO_4$ 0.6 g/l. Using this optimized fermentation method, the yield of laccase was increased 59.68 times to 67.258 U/ml compared with the laccase production with an unoptimized medium. This is the first report on the statistical optimization of laccase production by Trichoderma harzianum ZF-2.

• Journal of applied mathematics & informatics
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• v.26 no.1_2
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• pp.337-347
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• 2008

Based on social welfare maximum theory, the optimal scale of power plants entering generation power market being is researched. A static non-cooperative game model for short-term optimization of power plants with different cost is presented. And the equilibrium solutions and the total social welfare are obtained. According to principle of maximum social welfare selection, the optimization model is solved, optimal number of power plants entering the market is determined. The optimization results can not only increase the customer surplus and improve power production efficiency, but also sustain normal profits of power plants and scale economy of power production, and the waste of resource can also be avoided. At last, case results show that the proposed model is efficient.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.5
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• pp.538-544
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• 2012

In this paper, design optimization of C-frame of a precision drilling and autorivet machine has been performed. The machine, Autoriveter has been developed by Korea Aerospace Industry (KAI), For current autoriveter, it is hard to achieve high efficiency because of heavy weight of the machine. In this paper, we suggest new structure of the current C-frame, a part of autoriveter, by optimization. The result of the study can give much profit for mass-production of the machine.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.658-668
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• 2009

Earth-moving operation has a great impact on the overall budget and schedule of any heavy civil projects. More often than not, the operational decisions are made largely based on field personnel's experience and judgment. In particular, decisions on earth moving operations by scraper-dozer fleets have been heavily influenced by the following belief: "The longer a dozer pushes a scraper for loading, the better earth-moving productivity is gained by the fleet." Even though there is some truth to this notion, scraper-dozer earth moving operations involve a much complex process that requires a systematic analysis for predicting the maximum production. To this end, this paper presents a spreadsheet-based scraper-dozer fleet operation model for its production optimization. Various optimization techniques, including a genetic-algorithm method, are presented for comparison and each technique's pros and cons are discussed.

• Journal of Microbiology and Biotechnology
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• v.28 no.6
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• pp.902-908
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• 2018

Optimization of the culture medium to maximize menaquinone-7 (MK-7) production by Bacillus subtilis strain KCTC 12392BP in static culture was carried out using statistical experimental methods, including one factor at a time, fractional factorial design, and response surface methodology (RSM). Maltose (carbon source), tryptone (nitrogen source), and glycerol (activator) were identified as the key medium components for MK-7 synthesis by the fractional factorial design, and were selected for statistical optimization by RSM. The statistical analysis indicated that, in the range that was studied, maltose, tryptone, and glycerol were all critical factors having profound effects on the production of MK-7, with their coefficients for linear and quadratic all significant at the p < 0.05 level. The established model was efficient and feasible, with a determination coefficient ($R^2$) of 0.9419. The predicted concentrations of maltose, tryptone, and glycerol in the optimal medium were determined as 36.78, 62.76, and 58.90 g/l, respectively. In this optimized medium, the maximum yield of MK-7 reached a remarkably high level of $71.95{\pm}1.00{\mu}g/ml$ after 9 days of static fermentation, which further verified the practicability of this optimized strategy.

• Journal of Institute of Control, Robotics and Systems
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• v.4 no.2
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• pp.235-245
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• 1998

This paper presents the fuzzy optimization model based scheduling methodology for the efficient production control of a FFS(FIexible Flow Shop) under the uncertain production environment. To develop the methodology, a fuzzy optimization technique is introduced in which the uncertain production capacity caused by the random events like the machine breakdowns or the absence of workers is modeled by fuzzy number. Since the problem is NP hard, the goal of this study is to obtain the near optimal but practical schedule in an efficient way. Thus, Lagrangian relaxation method is used to decompose the problem into a set of subproblems which are easier to solve than the original one. Also, to construct the feasible schedule, a heuristic algorithm was proposed. To evaluate the performance of the proposed method, computational experiments, based on the real factory data, are performed. Then, the results are compared with those of the other methods, the deterministic one and the existing one used in the factory, in the various performance indices. The comparison results demonstrate that the proposed method is more effective than the other methods.