• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.3
• /
• pp.302-307
• /
• 2015

The automobile is an important means of transportation. For this reason, the automotive wheel is also an important component in the automotive industry because it acts as a load support and is closely related to safety. Thus, the wheel design is a very important safety aspect. In this paper, an optimal design for minimizing automotive wheel stress and increasing wheel safety is described. To study the optimal design, a central composite design (CCD) and D-optimal design theory are applied, and the approximate function using the response surface method (RSM) is generated. The optimal solutions using the non-dominant sorting genetic algorithm (NSGA-II) are then derived. Comparing CCD and D-optimal solution accuracy and verified the CCD can deduce more accuracy optimal solutions.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.3
• /
• pp.308-313
• /
• 2015

In this research, a multi-objective optimal design of a scroll compressor lower frame was approximated, and the design parameters of the lower frame were selected. The sensitivity of the design parameters was induced through a parameter analysis, and the thickness was determined to be the most sensitive parameter to stress and deflection. All of the design parameters regarding the mass are sensitive factors. It was formulated for the problem about stress and deflection to be caused by the axial load. The sensitivity of the design variables was determined using an orthogonal array for the parameter analysis. Using the central composite and D-optimal designs, a second polynomial approximation of the objective and constraint functions was formulated and the accuracy was verified through an R-square. These functions were applied to the optimal design program (NSGA-II). Through a CAE analysis, the effectiveness of the central composite and D-optimal designs was determined.

• Journal of Microbiology and Biotechnology
• /
• v.12 no.3
• /
• pp.360-366
• /
• 2002

Central composite experimental design was employed to determine the optimal concentration of medium constituents for griseofulvin production by Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvum MTCC 2004. The optimal concentration of sucrose, $K_2HPO_4,\;NaNO_3,\;and\;FeSO_4{\cdot}7H_2O$ were found to be 48.08 g/1, 1.228 g/1 , 2.7 g/1, and 0.011 g/1, respectively, for Penicillium griseofulvum MTCC 1898, and for Penicillium griseofulvum MTCC 2004, 23.52 g/1, 43.67 g/1, and 0.0434 g/1 of glucose, lactose, and $MnSO_4{\cdot}H_2O$, respectively. The yield of griseofulvin under optimal composition of medium constituents increased by 1.26 and 1.38 times than prior to optimization, for Penicillium griseofulvum MTCC 1898 and Penicillium griseofulvutn MTCC 2004, respectively.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.2
• /
• pp.211-216
• /
• 2015

Recently, because of the growth in the leisure industry and interest in health, the demand for bicycles has increased. In this research, considering the vertical load on a bike frame under static state conditions, the deflection and mass of the bike frame were minimized by satisfying the service condition and performing optimization. The thickness of the bicycle-frame tube was set to a design variable, and its sensitivity was confirmed by an analysis of means (ANOM). To optimize the solution, a response-surface-method (RSM) model was constructed using D-Optimal and central composite design(CCD). The optimization was performed using a non-dominant sorting genetic algorithm (NSGA-II), and the optimal solution was verified by finite-element analysis.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.2
• /
• pp.186-191
• /
• 2015

Presently, rapidly changing and unstable global economic environments demand engineers. Products should be designed to increase profits by lowering costs and provide distinguished performance compared with competitors. This study aims to optimize the design of the power-transmission drive shaft. The mass is reduced as an objective function, and the stress is constrained under a constant value. To reduce the number of experiments, CCD (central composite design) and D-Optimal are used for the experimental design. RSM (response surface methodology) is employed to construct a regression model for the objective functions and constraint function. In this problem, there is only one objective function for the mass. The other objective function gives 1; thus, NSGA-II is used.

• Journal of Korean Society for Quality Management
• /
• v.43 no.3
• /
• pp.453-466
• /
• 2015

Purpose: The purpose of this study is to design a systematic method to estimate optimal operation conditions of design variables for an electronic device alignment system. Method: The 2-level factorial design and the central composite design are used in order to plan experiments. Based on the experiment results, a regression model is established to find optimal conditions for the design variables. Results: 3 of 5 design variables are selected as major factors that affect the alignment system significantly. The optimized condition for each variable is estimated by using a sequential experiment plan and a quadratic regression model. Conclusion: The method designed in this study provides an efficient and systematic plan to select the optimized operation condition for the design variables. The method is expected to improve inspection accuracy of the system and reduce the development cost and period.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.24 no.2
• /
• pp.192-197
• /
• 2015

In many fields, the importance of reducing weight is increasing. A product should be designed such that it is profitable, by lowering costs and exhibiting better performance than other similar products. In this study, the mass and deflection of steel structures have to be reduced as objective functions under constraint conditions. To reduce computational analysis time, central composite design(CCD) and D-Optimal are used in design of experiments(DOE). The accuracy of approximate models is evaluated using the $R^2$ value. In this study, the objective functions are multiple, so the non-dominant sorting genetic algorithm(NSGA-II), which is highly efficient, is used for such a problem. In order to verify the validity of Pareto solutions, CAE results and Pareto solutions are compared.

• Journal of the Korean Society for Precision Engineering
• /
• v.32 no.9
• /
• pp.815-824
• /
• 2015

In this study, we conducted the approximate multi-objective optimization of gap sizes of pressurized-water reactor (PWR) annular fuels. To determine the contacting tendency of the inner-outer gaps between the annular fuel pellets and cladding, thermoelastic-plastic-creep (TEPC)analysis of PWR annular fuels was performed, using in-house FE code. For the efficient heat transfer at certain levels of stress, we investigated the tensile, compressive hoop stress and temperature, and optimized the gap sizes using the non-dominant sorting genetic algorithm (NSGA-II). For this, response surface models of objective and constraint functions were generated, using central composite (CCD) and D-optimal design. The accuracy of approximate models was evaluated through $R^2$ value. The obtained optimal solutions by NSGA-II were verified through the TEPC analysis, and we compared the obtained optimum solutions and generated errors from the CCD and D-optimal design. We observed that optimum solutions differ, according to design of experiments (DOE) method.

• The KSFM Journal of Fluid Machinery
• /
• v.16 no.4
• /
• pp.22-27
• /
• 2013

The purpose of this paper is to perform the structural design of the small scale vertical-axis wind turbine (VAWT) blade using a response surface method(RSM). First, the four design factors that have a strong influence on the structural response of blade were selected. Analysis conditions were calculated by using the central composite design(CCD), which is a typical design of experiment for the response surface method(RSM). Also, the significance of the central composite design(CCD) was verified using analysis of variance(ANOVA). The finite element analysis was performed for the selected analytical conditions for the application of response surface method(RSM). Finally, a optimization problem was solved with a objective function of blade weight and a constraint of allowable stress to achieve a optimal structural design of blade.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.6 no.4
• /
• pp.1-8
• /
• 1998

In order to solve the conflict problem between the ride comfort and the road holding, the optimal design of shock absorber that minimizes the r.m.s. of sprung mass vertical acceleration and pitch rate with the understeer characteristics constraints in the high speed stability is proposed. The design of experiments and the nonlinear optimization algorithm are used together to obtain the optimal design of shock absorber. The second order regression models of the input variables(front and rear damping coefficients) and the output variables (ride comfort index and road holding one) are obtained by the central composite design in the design of experiments. Then the optimal design of shock absorber can be systematically adjusted with applying the nonlinear optimization algorithm to the obtained second order regression model. The frequency response analysis of sprung mass acceleration and pitch rate shows the effectiveness of the proposed optimal design of shock absorber in the sprung mass resonance range with the understeer characteristics constraints.