• Communications for Statistical Applications and Methods
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• v.6 no.1
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• pp.53-68
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• 1999

To improve the slow convergence property of the steepest ascent type algorithm for continuous D-optimal design problems. we develop a new algorithm. We apply the nonlinear system of equations as the necessary condition of optimality and develop the two-point algorithm that solves the problem of clustering. Because of the nature of the steepest coordinate ascent algorithm avoiding the problem of clustering itself helps the improvement of convergence speed. The numerical examples show the performances of the new method is better than those of various steepest ascent algorithms.

• Journal of Industrial Technology
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• v.31 no.A
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• pp.27-31
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• 2011

In many industrial experiments, some practical constraints often force factors in an experiment to be much harder to change than others. Such an experiment involves randomization restrictions and it can be thought of as split-plot experiment. This paper investigates the path of steepest ascent/descent within a split-plot structure. A method is proposed for calculating the coordinates along the path.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.68-72
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• 2005

Leuconostoc citreum is one of the representative strains of Leuconostoc spp. that show fast growth rates in fermented vegetables. Sequential experimental designs including the Plackett-Burman design, fractional factorial design, steepest ascent analysis, central composite design and response surface methodology were introduced tooptimize and improve the medium for Leuconostoc citreum. Fifteen medium ingredients were examined and glucose (20 g/l), yeast extract (12.5 g/l), sodium acetate trihydrate (6.12 g/l), potassium phosphate (42.55 g/l) and dibasic ammonium citrate (4.12 g/l)were chosen as the best components to give a critical and positive effect for cell-growth. The biomass was increased to 2.79 g/l (169%), compared to the 1.65 g/l in MRS medium.

• Biotechnology and Bioprocess Engineering:BBE
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• v.9 no.4
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• pp.278-284
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• 2004

Leuconostoc citreum is one of the representative strains of Leuconostoc spp. that show fast growth rates in fermented vegetables. Sequential experimental designs including the Plackett-Burman design, fractional factorial design, steepest ascent analysis, central composite design and response surface methodology were introduced to optimize and improve the medium for L. citreum. Fifteen medium ingredients were examined and glucose ($20 g/\ell$), yeast extract ($12.5g/\ell$), sodium acetate trihydrate ($6.12g/\ell$), potassium phosphate ($42.55g/\ell$), and dibasic ammonium citrate ($4.12g/\ell$), were chosen as the best components to give a critical and positive effect for cell-growth. The biomass was increased to ($2.79g/\ell$), (169%), compared to the $1.65g/\ell$ in MRS 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.

• Microbiology and Biotechnology Letters
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• v.2 no.2
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• pp.63-77
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• 1974

The optimal operation problem of enzyme reactor of double inhibitions are dealt with Maximum Principle and Steepest Ascent Method. The operation policy of the intial concentration and amount of substrate, reaction time and the method of cross feed of substrate are determined in a system of reactor of constant volume add with cross feed of substrate. The policy for the soluble enzyme and the immobilized enzyme are greatly different from each other, and the performance index, the profit per unit time, of the latter are nearly twice greater than that of the former.

• Journal of Korean Institute of Industrial Engineers
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• v.15 no.1
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• pp.65-75
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• 1989

This study complements the previous studies on workload distribution problems in Flexible Manufacturing Systems. Specifically, we consider the problem in two perspectives, the long-range policy and the short and medium-term planning and control. The long-term loading policy focusses on identifying the optimal loading of the system characterized by either balanced loading or unique unbalanced loading for which a steepest ascent method is developed. These results are then applied to study the optimal medium and short-term planning and control problems, for which a truncated dynamic programming method is developed in order to obtain the optimal allocation of the given operation mix of part types to work stations.

• KSBB Journal
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• v.24 no.1
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• pp.30-40
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• 2009

Statistical optimization of the production medium was carried out in order to find an optimal medium composition in itaconic acid fermentation process. Itaconic acid utilized in the manufacture of various synthetic resins is a dicarboxylic acid biosynthesized by fungal cells of Aspergillus terreus in a branch of the TCA cycle via decarboxylation of cis-aconitate. Through OFAT (one factor at a time) experiments, six components (glucose, fructose, sucrose, soluble starch, soybean meal and cottonseed flour) were found to have significant effects on itaconic production among various carbon- and nitrogen-sources. Hence, using these six factors, interactive effects were investigated via fractional factorial design, showing that the initial concentrations of sucrose and cottonseed flour should be high for enhanced production of itaconic acid. Furthermore, through full factorial design (FFD) experiments, negative effects of $KH_2PO_4$ and $MgSO_4$ on itaconic acid biosynthesis were demonstrated, when excess amounts of the each component were initially added. Based on the FFD analysis, further statistical experiments were conducted along the steepest ascent path, followed by response surface method (RSM) in order to obtain optimal concentrations of the constituent nutrients. As a result, optimized concentrations of sucrose and cottonseed flour were found to be 90.4g/L and 53.8g/L respectively, with the corresponding production level of itaconic acid to be 4.36 g/L (about 7 fold higher productivity as compared to the previous production medium). From these experimental results, it was assumed that optimum ratio of the constituent carbon (sucrose) and nitrogen (cottonseed flour) sources was one of the most important factors for the enhanced production of itaconic acid.

• Korean Chemical Engineering Research
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• v.54 no.1
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• pp.44-51
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• 2016

The powder core, conventionally fabricated from iron particles coated with insulator, showed large eddy current loss under high frequency, because of small specific resistance. To overcome the eddy current loss, the increase in the specific resistance of powder cores was needed. In this study, copper oxide coating onto electrically conductive iron particles was performed using a planetary ball mill to increase the specific resistance. Coating factors were optimized by the Response surface methodology. The independent variables were the CuO mass fraction, mill revolution number, coating time, ball size, ball mass and sample mass. The response variable was the specific resistance. The optimization of six factors by the fractional factorial design indicated that CuO mass fraction, mill revolution number, and coating time were the key factors. The levels of these three factors were selected by the three-factors full factorial design and steepest ascent method. The steepest ascent method was used to approach the optimum range for maximum specific resistance. The Box-Behnken design was finally used to analyze the response surfaces of the screened factors for further optimization. The results of the Box-Behnken design showed that the CuO mass fraction and mill revolution number were the main factors affecting the efficiency of coating process. As the CuO mass fraction increased, the specific resistance increased. In contrast, the specific resistance increased with decreasing mill revolution number. The process optimization results revealed a high agreement between the experimental and the predicted data ($Adj-R^2=0.944$). The optimized CuO mass fraction, mill revolution number, and coating time were 0.4, 200 rpm, and 15 min, respectively. The measured value of the specific resistance of the coated pellet under the optimized conditions of the maximum specific resistance was $530k{\Omega}{\cdot}cm$.

• Journal of Microbiology and Biotechnology
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• v.20 no.4
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• pp.835-843
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• 2010

The objectives of this study were to investigate the effect of fermentation medium on the hydroxyl radical scavenging activity of exopolysaccharides from Inonotus obliquus by response surface methodology (RSM). A two-level fractional factorial design was used to evaluate the effect of different components of the medium. Corn flour, peptone, and $KH_2PO_4$ were important factors significantly affecting hydroxyl radical scavenging activity. These selected variables were subsequently optimized using path of steepest ascent (descent), a central composite design, and response surface analysis. The optimal medium composition was (% w/v): corn flour 5.30, peptone 0.32, $KH_2PO_4$ 0.26, $MgSO_4$ 0.02, and $CaCl_2$ 0.01. Under the optimal condition, the hydroxyl radical scavenging rate (49.4%) was much higher than that using either basal fermentation medium (10.2%) and single variable optimization of fermentation medium (35.5%). The main monosaccharides components of the RSM optimized polysaccharides are rhamnose, arabinose, xylose, mannose, glucose, and galactose with molar proportion at 1.45%, 3.63%, 2.17%, 15.94%, 50.00%, and 26.81%.