• 대한환경공학회지
• /
• 제39권10호
• /
• pp.568-574
• /
• 2017

본 연구는 폐목재로부터 organosolv 공정을 이용해서 리그닌을 분리할 때 영향을 미치는 주요 3개의 반응조건(반응시간($X_1$), 산 촉매의 농도($X_2$) 및 반응온도($X_3$))을 리그닌 회수율(y) 기준으로 최적화하였다. 중심합성계획법(central composite design, CCD)에 따라 반응온도 $136.4-203.6^{\circ}C$, 산촉매 농도 0-2.5%, 반응시간 26.36-93.64 분의 범위를 가진 실험계획을 수행해서 2차 모델식 및 최적조건을 수립하였다. 2차 모델식은 $y=-79.89+0.91X_1+9.8X_2-2.54{\times}10^{-3}X_1{^2}-2.11X_2{^2}$와 같이 얻었으며, 결정계수(coefficient of determination, $R^2$) 값은 0.8531으로 10% 이내의 유의수준에서 유의성을 나타냈다. 2차 모델식에 따라 예측되는 최고 리그닌 회수율은 12.46 g/100 g of dry wood이며 이때 최적 반응 조건은 반응온도 $178.2^{\circ}C$, 산 촉매 농도 2.32%으로 나타났다. 폐목재 대상 organosolv 공정에서의 리그닌 수율은 반응온도보다는 산 촉매 농도의 영향이 더 크게 나타났으며 반응시간에 의한 영향은 없는 것으로 나타났다. 모델의 변동성 분석(analysis of variance, ANOVA)에 따르면 리그닌 수율(y)에 대한 모델식의 유의확률은 p<0.001로 높은 유의성을 보였다. 최적조건에서 모델의 재현성을 검증한 결과 모델식이 실제공정을 적절하게 모사한 것으로 나타났다.

• 한국기계가공학회지
• /
• 제15권3호
• /
• pp.8-14
• /
• 2016

Medical bed head consoles (BHC) are generally used to increase the efficiency of medical equipment and speed the medical treatment response time. The BHC design has been consistently improved including a movable shelf unit that is embedded to mount stably medical instruments on the lower part of the main console. The cost of a BHC can be reduced through design optimization to limit the overall weight. However, as the size of a head console might decrease due to design optimization, the BHC deflection could be increased. In this study, multi-objective optimal design was adopted to consider this BHC design problem. In order to reduce the cost of optimization planning, an approximate model was applied for the design optimization. In the context of approximate optimization, we used the response surface method and non-dominant sorting genetic algorithm developed from various fields. Multi-objective optimal solutions were also compared with a single objective optimal design.

• 한국축산식품학회지
• /
• 제38권2호
• /
• pp.240-250
• /
• 2018

This study was undertaken to find the optimum soy-peptone, glucose, yeast extract, and magnesium sulfate amounts for the maximum growth of Lactobacillus plantarum JNU 2116 and to assess the effects of these medium factors through the use of response surface methodology. A central composite design was used as the experimental design for the allocation of treatment combinations. In the analysis of the experiment, due to a significant lack of fit of the second-order polynomial regression model that was used at first, cubic terms were added to the model, and then two-way interaction terms were deleted from the model since they were found to be all statistically insignificant. A relative comparison among the four factors showed that the growth of L. plantarum JNU 2116 was affected strongly by yeast extract, moderately by glucose and peptone, and slightly by magnesium sulfate. The estimated optimum amounts of the medium factors for the growth of L. plantarum JNU 2116 are as follows: soy-peptone 0.213%, glucose 1.232%, yeast extract 1.97%, and magnesium sulfate 0.08%. These results may contribute to the production of L. plantarum L67 as a starter culture that may have potential application in yogurt and fermented meat products.

• Structural Engineering and Mechanics
• /
• 제73권5호
• /
• pp.501-513
• /
• 2020

In the present work, the optimization of machining parameters to achieve the desired technological parameters such as surface roughness, tool radial vibration and material removal rate have been carried out using response surface methodology (RSM). The hard turning of EN19 alloy steel with coated carbide (GC3015) cutting tools was studied. The main problem faced in manufacturer of hard and high precision components is the selection of optimum combination of cutting parameters for achieving required quality of surface finish with maximum production rate. This problem can be solved by development of mathematical model and execution of experiments by RSM. A face centred central composite design (FCCD), which comes under the RSM approach, with cutting parameters (cutting speed, feed rate and depth of cut) was used for statistical analysis. A second-order regression model were developed to correlate the cutting parameters with surface roughness, tool vibration and material removal rate. Consequently, numerical and graphical optimization were performed to obtain the most appropriate cutting parameters to produce the lowest surface roughness with minimal tool vibration and maximum material removal rate using desirability function approach. Finally, confirmation experiments were performed to verify the pertinence of the developed mathematical models.

• Archives of Pharmacal Research
• /
• 제23권5호
• /
• pp.507-512
• /
• 2000

This study set out to improve the physical and pharmaceutical characteristics of the present formulation using an appropriate experimental design. The work described here concerns the formulation of the dispersible tablet applying direct compression method containing roxithromycin in the form of coated granules. In this study $2^3$ factorial design was used as screening test model and Central Composite Design (CCC) associated with response surface methodology was used as optimization study model to develop and to optimize the proper formulation of roxithromycin dispersible tablet. The three independent variables investigated were functional excipients like binder (X1), disintegrant (X2) and lubricant (X3). The effects of these variables were investigated on the following responses: hardness (Y1), friability (Y2) and disintegration time (Y3) of tablet. Three replicates at the center levels of the each design were used to independently calculate the experimental error and to detect any curvature in the response surface. This enabled the best formulations to be selected objectively. The effect order of each term to all response variable was X3> X2> Xl> X1＊X2> X2＊X2> X2＊X3> X3＊X3> Xl＊X3> Xl＊Xl and model equations on each response variables were generated. Optimized compositions of formula were accordingly computed using those model equations and confirmed by following demonstration study. As a result, this study has demonstrated the efficiency and effectiveness of using a systematic formulation optimization process to develop the tablet formulation of roxithromycin dispersible tablet with limited experiment.

• Environmental Engineering Research
• /
• 제15권2호
• /
• pp.63-70
• /
• 2010

In this study, the response surface method and experimental design were applied as an alternative to conventional methods for the optimization of coagulation tests. A central composite design, with 4 axial points, 4 factorial points and 5 replicates at the center point were used to build a model for predicting and optimizing the coagulation process. Mathematical model equations were derived by computer simulation programming with a least squares method using the Minitab 15 software. In these equations, the removal efficiencies of turbidity and total organic carbon (TOC) were expressed as second-order functions of two factors, such as alum dose and coagulation pH. Statistical checks (ANOVA table, $R^2$ and $R^2_{adj}$ value, model lack of fit test, and p value) indicated that the model was adequate for representing the experimental data. The p values showed that the quadratic effects of alum dose and coagulation pH were highly significant. In other words, these two factors had an important impact on the turbidity and TOC of treated water. To gain a better understanding of the two variables for optimal coagulation performance, the model was presented as both 3-D response surface and 2-D contour graphs. As a compromise for the simultaneously removal of maximum amounts of 92.5% turbidity and 39.5% TOC, the optimum conditions were found with 44 mg/L alum at pH 7.6. The predicted response from the model showed close agreement with the experimental data ($R^2$ values of 90.63% and 91.43% for turbidity removal and TOC removal, respectively), which demonstrates the effectiveness of this approach in achieving good predictions, while minimizing the number of experiments required.

• 한국항공우주학회지
• /
• 제36권2호
• /
• pp.99-104
• /
• 2008

본 연구에서는 신경망에 기반한 불확실성 모델을 이용하여 전투기 날개 형상의 강건 최적 설계를 수행하였다. 불확실성 모델을 구축하기 위하여 공력성능과 이들의 민감도 정보를 중심합성법으로 선정된 실험점에서 구하였으며, 이 때 3차원 오일러 방정식과 adjoint변수방법이 사용되었다. 또한 비선형성 모사능력이 뛰어난 신경망모델을 이용함으로써 공력성능계수의 민감도 정보를 효율적이고 정확하게 예측하는 것이 가능하였다. 이와 같은 방법으로 구하여진 강건 최적 설계 결과로부터, 불확실성 모델의 변동과 신뢰도 수준의 변화가 증가할수록 목적함수 및 제약조건에 대한 강건성이 향상되는 것을 확인할 수 있었다.

• Journal of Welding and Joining
• /
• 제27권5호
• /
• pp.81-87
• /
• 2009

Recently, extruded aluminium-alloy panels have been used in the car bodies for the purpose of the light-weight of railway vehicles and FSW(Friction Stir Welding), which is superior to the arc weldings, has been applied in the railway vehicles. This paper presents the optimum design of the FSW process on A6005 extruded alloy for railway vehicles to improve its mechanical properties. Rotational speed, welding speed and tilting angle of the tool tip were chosen as design parameters. Three objective functions were determined; maximizing the tensile strength, minimizing the hardness and maximizing the difference between the normalized tensile strength and hardness. The tensile tests and the hardness tests for fifteen FSW experiments were carried out according to the central composite design table. Recursive model functions on three characteristic values, such as the tensile strength, the hardness difference(${\Delta}Hv$) and the difference of normalized tensile strength and ${\Delta}Hv$, were estimated according to the classical response surface analysis methodology. The reliability of each recursive function was verified by F-test using the analysis of variance table. Sensitivity analysis on each characteristic value was done. Finally, the optimum values of three design parameters were found using Sequential Quadratic Programming algorithm.

• Journal of Microbiology and Biotechnology
• /
• 제20권4호
• /
• pp.737-748
• /
• 2010

Glutaminase production in Zygosaccharomyces rouxii by solid-state fermentation (SSF) is detailed. Substrates screening showed best results with oatmeal (OM) and wheatbran (WB). Furthermore, a 1:1 combination of OM:WB gave 0.614 units/gds with artificial sea water as a moistening agent. Evaluation of additional carbon, nitrogen, amino acids, and minerals supplementation was done. A central composite design was employed to investigate the effects of four variables (viz., moisture content, glucose, corn steep liquor, and glutamine) on production. A 4-fold increase in enzyme production was obtained. Studies were undertaken to analyze the time-course model, the microbial growth, and nutrient utilization during SSF. A logistic equation ($R^2$=0.8973), describing the growth model of Z. rouxii, was obtained with maximum values of ${\mu}_m$ and $X_m$ at $0.326h^{-1}$ and 7.35% of dry matter weight loss, respectively. A goodfit model to describe utilization of total carbohydrate ($R^2$=0.9906) and nitrogen concentration ($R^2$=0.9869) with time was obtained. The model was used successfully to predict enzyme production ($R^2$=0.7950).

• 공업화학
• /
• 제31권4호
• /
• pp.377-382
• /
• 2020

아세틸렌 흡착 공정을 위한 MOF-235 합성의 최적화를 위해 순차적인 실험 계획법을 사용하였다. 이를 위하여 두 가지 실험 계획법이 적용되었는데, screening을 위한 2단계 요인 설계와 반응표면 분석법 중에 하나인 중심합성 계획이다. 본 연구에서는 2³ 요인 설계법을 이용하여 MOF-235의 결정도에 대한 합성 온도, 합성 시간 및 혼합 속도의 영향을 평가하였다. MINITAB 19 소프트웨어에 따라 설계된 16번의 MOF-235 합성 실험을 수행하였다. XRD 분석을 바탕으로 Half-Normal, Pareto, Residual, Main 및 Interaction 효과를 구하였다. 시험 결과의 분산 분석(ANOVA)을 통해 합성 온도 및 시간이 MOF-235의 결정도에 중요한 영향을 미친다는 것을 분석하였다. 이후, 중심합성 계획법을 이용하여 아세틸렌 흡착성능 최적화를 MOF-235의 선정된 합성 조건을 바탕으로 수행하였다. 설계된 9번의 흡착실험을 통해 도출된 결과를 2차 모델 방정식을 이용하여 계산하였다. 아세틸렌의 최대 흡착 용량(18.7 mmol/g)은 86.3 ℃ 및 28.7 h의 최적의 조건에서 합성된 MOF-235에서 얻을 수 있다고 예측하였다.