• Journal of the Korean Data and Information Science Society
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• v.26 no.6
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• pp.1295-1303
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• 2015

In a mixture experiment, one may be interested in estimating not only main effects but also some interactions. Main effects and interactions may be estimated through appropriate designs such as simplex-centroid designs. However, the estimability problems, implied by the sum to one functional relationship among the factors, have strong consequences on the confounding and identifiability of models for such designs. To handle these problems, we address homogeneous polynomial model based on the computational commutative algebra (CCA) instead of using $Scheff{\acute{e}}s$ canonical model which is typically used. The problem posed here is to give how to choose estimable main effects and also some low-degree interactions. The theory is tested using a fraction of simplex-centroid designs aided by a modern computational algebra package CoCoA.

• Computers and Concrete
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• v.5 no.1
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• pp.1-20
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• 2008

In this study, the effects and the interactions of water content, SP-binder ratio, and water-binder ratio on the workability performance of concrete were investigated. The experiments were designed based on flatted simplex-centroid experiment design modified from standard simplex-centroid one. The data gotten from the design was used to build the concrete slump model using neural networks. Research reported in this paper shows that a small number of slump experiments can be performed and meaningful data obtained with the experiment design. Such data would be suitable for building slump model using neural networks. The trained network can be satisfactorily used for exploring the effects of the components and their interactions on the workability of concrete. It has found that a high water content and a high SP/b ratio is essential for high workability, but achieving this by increasing these parameters will not in itself guarantee high workability. The w/b played a very important role in producing workability and had rather profound effects; however, the medium value about 0.4 is the best w/b to reach high slump without too much effort on trying to find the appropriate water content and SP/b.

• Journal of the Korean Statistical Society
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• v.17 no.2
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• pp.121-133
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• 1988

In this paper a class of mixture designs for estimating the slope of second order Scheffe polynomial response surfaces for mixture experiments with q components is presented. The variance of the estimated directional slope at a point is a function of the direction of the slope and the design. If the variance is averaged over all possible directions in the (q-1)-dimensional simplex, the averaged variance is only a function of the point and the design. By choice of design, it is possible to make this variance constant for all points equidistant from the centroid point. This property is called "slope-rotatability over al directions in the simplex", and the necessary and sufficient conditions for mixture design to have this property are given and proved. The class of designs with this property is compared with other mixture designs and discussed.discussed.

• Journal of the Korea Convergence Society
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• v.11 no.5
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• pp.35-41
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• 2020

This study was conducted to develop the efficient system for starch hydrolysis suppression using rutin, quercetin and dietary fiber through the statistical mixture design. The three components were replaced with wheat flour at the level of 10% and the mixed gel with three components was characterized by in vitro starch digestion. The mixture design was applied by simplex-centroid experimental model. The quadratic model (R²=0.86) was well fitted and the obtained regression equation indicated that the significant positive effects was observed in the quercetin and fiber mixture. Based on the statistical results, the best mixing ratio of quercetin and fiber was 72: 28 that led to the lowest predicted glycemic index (pGI). Their interactions on the pGI of starch digestibility were clearly visualized in the 3D surface plot. These results suggested that the mixture of quercetin and fiber interact strongly with wheat flour, consequently retarding starch hydrolysis by 15%.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.22-28
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• 2004

Livestock industry requires alternatives of antibiotics to prevent environmental pollution and to maintain public health. We herein report on an effective method to reduce ammonia from livestock manure, and confirmed environmentally-friendly livestock production by adding three types of yeast probiotics, Pichia farinosa SKM-1, Pichia anomala SKM-T, and Galactomyces geotrichum SJM-59, into the feed stuff, separately and/or mixed, and these three types of yeasts were administered to the Hy-line brown layers for 8 weeks. Compared with control, the laying performance, the egg quality, and the number of intestinal lactic acid producing bacteria of the treated group were improved and/or increased significantly. Pichia anomala SKM-T potently reduced ammonia production from poultry manure, and the other strains were also able to reduce the ammonia from it. The optimum condition for the reduction of ammonia with Pichia farinosa SKM-1, Pichia anomala SKM-T, and Galactomyces geotrichum SJM-59 was obtained by using the augmented centroid-simplex design. The ratio of optimum condition was Pichia farinosa SKM-1:Pichia anomala SKM-T:Galactomyces geotrichum SJM-59=0.295:0.209:0.080, and the estimate was -123.36 (p=0.0l38). An ability to reduce the ammonia production from livestock manure was maintained at $30^{\circ}C$ for 15 weeks.

• Environmental Engineering Research
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• v.24 no.4
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• pp.662-669
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• 2019

Anaerobic digestion is a popular sewage sludge (Ss) treatment method as it provides significant pollution control and energy recovery. However, the low C/N ratio and poor biodegradability of Ss necessitate pretreatment methods that improve solubilization under anaerobic conditions in addition to anaerobic co-digestion with other substrates to improve the process efficiency. In this study, three pretreatment methods, namely microwave irradiation, ultrasonication, and heat treatment, were investigated, and the corresponding improvement in methane production was assessed. Additionally, the simplex centroid design method was utilized to determine the optimum mixture ratio of food waste (Fw), livestock manure (Lm), and Ss for maximum methane yield. Microwave irradiation at 700 W for 6 min yielded the highest biodegradability (62.0%), solubilization efficiency (59.7%), and methane production (329 mL/g VS). The optimum mixture ratio following pretreatment was 61.3% pretreated Ss, 28.6% Fw, and 10.1% Lm. The optimum mixture ratio without pretreatment was 33.6% un-pretreated Ss, 46.0% Fw, and 20.4% Lm. These results indicate that the choice of pretreatment method plays an important role in efficient anaerobic digestion and can be applied in operational plants to enhance methane production. Co-digestion of Ss with Fw and Lm was also beneficial.

• Journal of Korean Institute of Industrial Engineers
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• v.29 no.4
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• pp.334-344
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• 2003

A mixture experiment is a special type of response surface experiment in which factors are the ingredients or components of a mixture, and the response is a function of the proportions of each ingredient. Evolutionary operation is useful to improve on-line full-scale manufacturing process by systematically changing the levels of the process variables without jeopardizing the product. This paper presents an evolutionary operation procedure with mixture variables for large-scale mixture production process which can be beneficial to practitioners who should improve on-line mixture quality while maintaining the production amount of the mixture product.

• Applied Chemistry for Engineering
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• v.32 no.5
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• pp.574-580
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• 2021

The main goal of this study was to find an optimal surfactant mixture composition for the development of the best performing cleansing products. Three different surfactants including sodium cocoyl alaninate (SCoA), cocamidopropyl betaine (CPB), and decyl glucoside (DG) were selected, which showed excellent properties in detergency, foaming height, and contamination rate through preliminary experiments. The experiments by simplex centroid design matrix for surfactant mixtures were performed, and the regression analysis was conducted with the experimental data. Surface response model equations, which is statistically significant (p < 0.05), were obtained. The optimal composition of the surfactant mixture was also determined as SCoA (0.22), CPB (0.78), and DG(0.00) from simultaneous optimization of three response variables.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.783-786
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• 2011

Various mushroom extracts were examined for their anti-Streptococcus mutans and anti-glucosyltransferase (GTase) activities. Mushrooms were extracted with chloroform, methanol, acetone, ethyl acetate, and distilled water. The chloroform, methanol, and ethyl acetate extracts showed higher antimicrobial activity than that of the others. The inhibitory effects of the chloroform, methanol, and ethyl acetate extracts of Lyopyllum ulmarium, which have high anti-microbial and GTase activities, on the growth of S. mutans were examined and the optimal ratio of solvents was also evaluated to investigate the influence of solvents using a simplex centroid design. The anti-cariogenic effects of the L. ulmarium extract on S. mutans was influenced by the solvent, and the optimum anti-cariogenic activity of the extract was obtained with the ratio of chloroform:methanol:ethyl acetate=1:1:1 (v/v/v). These results suggest that solvent selection is an important factor to extract anti-cariogenic materials effectively from mushrooms.