• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.9
• /
• pp.1183-1188
• /
• 2013

The reliability of hydraulic equipment used in power plants is especially important because failures that occur in the power plant can have a great ripple effect on human lives and financial losses. In this study, specimens using the materials used in the spool and sleeve of hydraulic valves of power plants have been produced, heat-treated, and tested under the precipitation conditions of phosphate ester hydraulic fluid with a variety of conditions. 23 full factorial designs have been applied to evaluate the significance of factors that affect the wear loss of the specimen, specifically, the load, velocity, and temperature. The significance evaluation was performed on the main effects and two-way interactions for wear loss based on the experiment results, and the mathematical equations between the wear loss and the three factors were derived from the analysis results.

• International Journal of Air-Conditioning and Refrigeration
• /
• v.17 no.2
• /
• pp.68-73
• /
• 2009

In this paper, a numerical study has been carried out to investigate the influence of volute geometries on the performance of a sirocco fan. In order to achieve an optimum volute design and explain the interactions between the different geometric configurations in the volute system, three-dimensional computational fluid dynamics and the 'design of experiment' method have been applied. Several geometric parameters, such as the volute expansion angle, the cut-off position and the bell mouth shape, are employed to improve efficiency and performance. $2^k$ factorial designs were performed to screen the most influential parameters and interactions, and showed that the cut-off position and the bell mouth shape are the most significant parameters. The optimum design was selected as a result of the response surface methodology, and effects of these parameters and their interactions were presented. From the results of computational analyses and experimental data, the performance and efficiency of the sirocco fan were successfully improved. Also, detailed effects of geometric variables of the volute system on the fan performance were discussed.

• Journal of the Korean Society of Costume
• /
• v.61 no.3
• /
• pp.51-62
• /
• 2011

The purpose of this study was to examine the visual evaluation of image according to the style, hue, value, and chroma of the male clothing and the preference of image. A quasi-experimental method was used for this study. The first factorial design was the $2{\times}3{\times}2{\times}2$ (style of upper clothes ${\times}$ hue ${\times}$ chroma ${\times}$ color of trousers), and the second factorial design was the $2{\times}3{\times}2$ (style of upper clothes ${\times}$ value ${\times}$ color of trousers). The styles of upper clothes were a soutien collar casual jacket and a polo shirt. The subjects were 509 female college students living in Seoul. Factor analysis showed five image categories of men's clothing: initiative, dignity, politeness, activity, and mildness. Yellow was evaluated as having the highest initiative and activity. Blue was shown to have lower mildness than red and yellow. The high saturated chroma was perceived to be higher initiative and activity than low chroma. The shirts were evaluated higher in activity and mildness than the casual jackets were. The beige pants were perceived to be higher in dignity and mildness than the dark blue pants. The high chroma jackets were perceived to be higher in both initiative and activity than the low chroma jackets. The navy blue pants with the upper clothes in low chroma blue were perceived to be higher in politeness than with the upper clothes in low chroma red or yellow. The low value clothes were perceived to be higher in both initiative and dignity.

• Journal of the Korean Society for Precision Engineering
• /
• v.28 no.4
• /
• pp.482-489
• /
• 2011

In practical design process, designer needs to find an optimal solution by using full factorial discrete combination, rather than by using optimization algorithm considering continuous design variables. So, ANOVA(Analysis of Variance) based on an orthogonal array, i.e. Taguchi method, has been widely used in most parts of industry area. However, the Taguchi method is limited for the shape optimization by using CAE, because the multi-level and multi-objective optimization can't be carried out simultaneously. In this study, a combined method was proposed taking into account of multi-level computational orthogonal array and TOPSIS(Technique for Order preference by Similarity to Ideal Solution), which is known as a classical method of multiple attribute decision making and enables to solve various decision making or selection problems in an aspect of multi-objective optimization. The proposed method was applied to a case study of the multi-level shape optimization of lower arm used to automobile parts, and the design space was explored via an efficient application of the related CAE tools. The multi-level shape optimization was performed sequentially by applying both of the neural network model generated from seven-level four-factor computational orthogonal array and the TOPSIS. The weight and maximum stress of the lower arm, as the objective functions for the multi-level shape optimization, showed an improvement of 0.07% and 17.89%, respectively. In addition, the number of CAE carried out for the shape optimization was only 55 times in comparison to full factorial method necessary to 2,401 times.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.38 no.4
• /
• pp.467-481
• /
• 2014

This study examined consumer responses of photos used in Internet shopping malls. The content analysis conducted a preliminary study of the top 100 online shopping malls to investigate current website practices. Stimuli based on the preliminary study. The present study was a $2{\times}2$ factorial design that evaluated two independent variables of product presentation and background. We analyzed 410 responses derived from the descriptive analysis, factor analysis, and covariance analysis through SPSS 20.0. The results showed that a product presentation was significantly different in attractiveness, informativeness, satisfaction, and repurchase intention after controlling apparel items and model. This product presentation in everyday life had greater mean values than product presentation with the posing model. The background had a significant mean difference in all consumer responses expect for attractiveness. Overall product presentation in everyday life and indoor cases were evaluated as most positive by the respondents. The findings provide practical implications for online shopping malls integrating product presentation.

• Applied Chemistry for Engineering
• /
• v.31 no.4
• /
• pp.377-382
• /
• 2020

A sequential design of experiments was employed to optimize MOF-235 synthesis for acetylene adsorption process. Two experimental designs were applied: a two-level factorial design for screening and a central composite design, one of response surface methodologies (RSM). In this study, 2³ factorial design of experiment was used to evaluate the effect of parameters of synthesis temperature and time, and also mixing speed on crystallinity of MOF-235. Experiments were conducted 16 times follwing MINITAB 19 design software for MOF-235 synthesis. Half-normal, pareto, residual, main and interaction effects were drawn based on the XRD results. The analysis of variance (ANOVA) of test results depicts that the synthesis temperature and time have significant effects on the crystallinity of MOF-235 (response variable). After screening, a central composite design was performed to optimize the acetylene adsorption capacity of MOF-235 based on synthesis conditions. From nine runs designed by MINITAB 19, the result was calculated using the second order model equation. It was estimated that the maximum adsorption capacity (18.7 mmol/g) was observed for MOF-235 synthesized at optimum conditions of 86.3 ℃ and 28.7 h.

• The KSFM Journal of Fluid Machinery
• /
• v.11 no.3
• /
• pp.36-42
• /
• 2008

In this paper, the performance characteristics of the impeller in a centrifugal pump were investigated using DOE(Design of Experiment) with commercial CFD software. Geometric parameters of vane plane development were defined with the meridional shape and frontal view of the impeller. The incidence angles and the exit blade angle were selected as main parameters using 2k factorial and the influences of selected design parameters were examined through the optimization process using RSM.

• Journal of the Korean Statistical Society
• /
• v.11 no.1
• /
• pp.1-11
• /
• 1982

Srivastava and Anderson(1970) illustrate a method of obtaining Balanced (but not orthogonal) Resolution $IV^*$ designs starting with a BIB design. The incidence matrix of a BIB design with parameters (v, b, r, k, and $\lambda$) is utilized to obtain Balanced Resolution $IV^*$ designs with m factors and n=2b runs, where $m \leq v$. In this paper, the same idea is extended to the case of PBIB designs to obtain Partially Balanced Resolution $IV^*$ designs. In the designs obtained here the variances are balanced and the covariances are partially balanced with respect to the main effects. A proof of this property of Partially Balanced Resoultion $IV^*$ designs is given. The efficiency of Partially Balanced Resolution $IV^*$ designs is also considered and examples of Partially Balanced Resoultion $IV^*$ designs are included.

• Applied Chemistry for Engineering
• /
• v.20 no.2
• /
• pp.234-240
• /
• 2009

$Mg(OH)_2$ particles were prepared by precipitation and a hydrothermal treatment to examine the effect of $MgCl_2$ concentration, alkali type and concentration, temperature, hydrothermal treatment on the formation of $Mg(OH)_2$ particles using full factorial design, as one of DOE (Design of experiment) methods. The primary particle size is similar to the secondary particle size for the samples after the hydrothermal treatment, where the average particle size of $Mg(OH)_2$ increased with increasing the concentration of $MgCl_2$ and hydrothermal temperature and decreasing alkali/Mg molar ratio. On the other hand, for the samples prepared from precipitation, the secondary particle size is larger than the primary particles due to aggregation. The difference in alkaline source is that the particles prepared from $NH_4OH$ exhibit the larger size with better dispersion than those from NaOH. Low density polyethylene and ethylene-co-vinyl acetate (LDPE-EVA) resin composed of the smaller secondary particle size of $Mg(OH)_2$ shows a higher limited oxygen index (LOI) at 50 and 55% loading, but the smaller primary particle size may result in a better grade in UL-94 tests. At the high loading of 60%, all samples with any preparation methods exhibit V-0 grade but the LOI value depends on not only primary particle size but also dispersion state.

• Journal of Microbiology and Biotechnology
• /
• v.20 no.11
• /
• pp.1597-1602
• /
• 2010

Chitinase is one of the most important mycolytic enzymes with industrial significance. This enzyme is produced by a number of organisms including bacteria. In this study, we describe the optimization of media components with increased production of chitinase for the selected bacteria, Stenotrophomonas maltophilia, isolated from soil. Different components of the defined media responsible for influencing chitinase secretion by the bacterial isolate were screened using Plackett-Burman experimental design and were further optimized by Box-Behnken factorial design of response surface methodology in liquid culture. Maximum chitinase production was predicted in medium containing 4.94 g/l chitin, 5.56 g/l maltose, 0.62 g/l yeast extract, 1.33 g/l $KH_2PO_4$, and 0.65 g/l $MgSO_4{\cdot}7H_2O$ using response surface plots and the point prediction tool of the DESIGN EXPERT 7.1.6 (Stat-Ease, USA) software.