• Proceedings of the Korea Society for Simulation Conference
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• 2004.05a
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• pp.41-47
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• 2004

중심합성계획(central composite design: ccd)은 반응 표면이 곡면적인 특성을 나타낼때 반응 공간을 추정하기 위해 사용되는 실험계획이다. 반응공간이 2차 회귀모형으로 나타나는 경우에 반응곡면의 변화량을 알기 위해서는 변수의 수준이 3이상이 되어야하는데 ccd는 적은 횟수의 실험으로 곡면을 효과적으로 추정하기 위해 2$^{k}$ 요인실험에 추가적으로 중심점(central point)과 축점(axial point)을 표본점에 포함시키는 계획이다. 본 연구에서는 시뮬레이션 실험에서 반응변수가 2차 회귀모형으로 근사되는 경우에 cod를 이용하여 관심 성과치의 반응표면을 추정하고자 한다. 일반적인 실험에서와는 달리 시뮬레이션 실험에서는 두개의 표본점(인자 수준의 조합)에서 분석자가 공통 난수계열(common random number series)을 부여하여 시뮬레이션 시스템 요소의 변화과정을 유사하게 통제할 수 있다. 일반적으로 공통난수법(common random number method)에 의해 얻어지는 두 표본점에서의 반응변수는 서로 양의 상관관계를 가지며 대조 난수(antithetic random number)에 의한 두 반응변수는 음의 상관성을 가지는 것으로 알려졌다. 본 연구는 ccd의 표본점에 공통난수와 대조난수 법을 이용하여 회귀모형의 파라미터를 효과적으로 추정하는 방법을 조사하고 이를 (s, S) 재고관리 모형에 적용하여 그 효율성을 평가하고자 한다.

• Steel and Composite Structures
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• v.26 no.1
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• pp.1-15
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• 2018

This study reported, the effect of random variation in system properties on bending response of single wall carbon nanotube reinforced composite (SWCNTRC) plates subjected to transverse uniform loading is examined. System parameters such as the SWCNT armchair, material properties, plate thickness and volume fraction of SWCNT are modelled as basic random variables. The basic formulation is based on higher order shear deformation theory to model the system behaviour of the SWCNTRC composite plate. A C0 finite element method in conjunction with the first order perturbation technique procedure developed earlier by the authors for the plate subjected to lateral loading is employed to obtain the mean and variance of the transverse deflection of the plate. The performance of the stochastic SWCNTRC composite model is demonstrated through a comparison of mean transverse central deflection with those results available in the literature and standard deviation of the deflection with an independent First Order perturbation Technique (FOPT), Second Order perturbation Technique (SOPT) and Monte Carlo simulation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.177-182
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• 2004

Electronic products are subjected to many different types of shock environment. As the Optical Disc Drive (ODD) market grows, the number of failures related to shock increases. Therefore, it is necessary to improve the performance of cushion package as well as the product design. Cushion materials such as expanded polystyrene are often used to protect electronic products from shock environment. In this paper, the drop analysis of the cushion package f3r optical disc drives was carried out with the explicit method of LS-DYNA and verified by the drop test. For the optimization of package, response surface approximation model was created using central composite design. As a result, cushioning performance was improved under the critical condition and practical design guidelines of cushion package were suggested.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2000.04a
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• pp.167-170
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• 2000

Recently the sub-micron structured substrates of 0.74 ${mu}ell$ track pitch and 800 $\AA$groove depth are required for DVD-RAM and the track pitch is expected to be narrower as the need for the information storage density is getting higher. For the accurate replication of the land-groove structure in the stamper to the plastic substrates it is important to control the injection -compression molding process such that the integrity of the replication for the land-groove structure is maximized. in the present study polycarbonate substrates were fabricated by injection comression molding and the land-groove structure regarded as one of mold temperature and the compression pressure on the integrity of the replication were examined experimentally. An efficient design methodology using the response surface method (RSM) the central composite design(CCD) technique and the analysis-of-variance (ANOVA) was developed to obtain the optimum processing conditions which maximize the integrity of the replication with a limited number of experiments.

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

• YAKHAK HOEJI
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• v.42 no.6
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• pp.545-551
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• 1998

Near Infrared transmittance Spectroscopy (NIRS) was used to evaluate and quantify the pharmaceutical active compounds. In the paper, taurine (2-Aminoethanesulfonic acid) was quantitatively analyzed in commercial pharmaceutical preparations. For calibration a central composite factorial design was used to determine concentrations of ingredients in reference samples. For the quantitative analysis of taurine, the most suitable data analysis method includes the calculation of second derivatives and a partial least squares regression (PLSR) model. By NIR spectrometry, combined with PLSR, the taurine concentration was successfully predicted with a relative standard error of prediction (SEP) lower than 1.04%.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.1
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• pp.119-124
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• 2013

In this paper, we analysed fatty acid methyl ester contents in the biodiesel which is produced from the newly developed biodiesel production equipment. The lard oil was used as the raw material through various experimental conditions. Thirty one experiments were conducted, which were based on the experimental conditions that designed by central composite design method. The effects of four independent variables, including reaction temperature, reaction time, oil to methanol molar ratio, and catalytic amount, were investigated at five levels using central composite design (CCD). Fatty acid methyl ester content was chosen dependent variable. Although the results of analysis of the surface with an irregular surface geometry showed that the biodiesel was partially impure after the reaction due to the natural characteristics of the lard oil as the raw material, we could confirm the relationship between them from the facts that the production amount of fatty acid methyl ester changes according to reaction temperature, reaction time, oil to methanol molar ratio, and catalytic amount.

• Journal of the Korean Wood Science and Technology
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• v.41 no.2
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• pp.87-99
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• 2013

Waste paper stands for the major biodegradable organic fraction of most of municipal solid waste. The potential of waste paper for glucose production was investigated in this current work. The pretreatment was accomplished by first subjecting waste paper to disintegration time (30 s), followed by ink removal of disintegrated waste paper using an deinking agent. Concentrated acid hydrolysis of waste paper with sulfuric acid was optimized to maximize glucose conversion. The concentrated acid hydrolysis conditions for waste paper (disintegrated time: 30 s, deinking agent loading : 15 ml) were optimized by using central composite design and response surface methodology. The optimization process employed a central composite design, where the investigated variables were acid concentration (60~80%), loading sulfuric acid (1~5 ml) and reaction time (1~5 h). All the tested variables were identified to have significant effects (p < 0.05) on glucose conversion. The optimum concentrated acid hydrolysis conditions were acid concentration of 70.8%, loading sulfuric acid of 3.2 ml and a reaction time of 3.6 h. This research of concentrated acid hydrolysis was a promising method to improve glucose conversion for waste paper.

• Advances in aircraft and spacecraft science
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• v.7 no.2
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• pp.151-168
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• 2020

The present study deals with the repair of composite structures by bonding composite patches. The composite structure is a carbon/epoxy laminate with stacking sequence [45/-45/0/90]S. The damaged zone is simulated by a central crack and repaired by bonding symmetrical composite patches. The repair is carried out using composite patches laminated from the same elemental folds as those of the cracked specimen. Three-dimensional finite element method is used to determine the energy release rate along the front of repaired crack. The effects of the repair technique used single or double patch, the stacking sequence of the cracked composite patch and the adhesive properties were highlighted on the variations of the fracture energy in mode I and mixed mode I + II loading.

• Composites Research
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• v.23 no.4
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• pp.7-13
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• 2010

A volume integral equation method (VIEM) is introduced for the solution of elastostatic problems in an unbounded isotropic elastic solids containing interacting multiple anisotropic inclusions subject to remote uniaxial tension. The method is applied to two-dimensional problems involving long parallel cylindrical inclusions. A detailed analysis of stress field at the interface between the matrix and the central inclusion is carried out for square and hexagonal packing of the inclusions. Effects of the number of anisotropic inclusions and various fiber volume fractions on the stress field at the interface between the matrix and the central inclusion are also investigated in detail. The accuracy of the method is validated by solving the single inclusion problem for which solutions are available in the literature.