• Communications for Statistical Applications and Methods
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• v.14 no.3
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• pp.483-495
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• 2007

In a general fractional factorial design, the n-levels of a factor are coded by the $n^{th}$ roots of the unity. Pistone and Rogantin (2007) gave a full generalization to mixed-level designs of the theory of the polynomial indicator function using this device. This article discusses the optimal blocking scheme for nonregular designs. According to hierarchical principle, the minimum aberration (MA) has been used as an important criterion for selecting blocked regular fractional factorial designs. MA criterion is mainly based on the defining contrast groups, which only exist for regular designs but not for nonregular designs. Recently, Cheng et al. (2004) adapted the generalized (G)-MA criterion discussed by Tang and Deng (1999) in studying $2^p$ optimal blocking scheme for nonregular factorial designs. The approach is based on the method of replacement by assigning $2^p$ blocks the distinct level combinations in the column with different blocks. However, when blocking level is not a power of two, we have no clue yet in any sense. As an example, suppose we experiment during 3 days for 12-run Plackett-Burman design. How can we arrange the 12-runs into the three blocks? To solve the problem, we apply G-MA criterion to nonregular mixed-level blocked scheme via the mixed-level indicator function and give an answer for the question.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.242-250
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• 2017

Purpose: This study was conducted to determine the appropriate operating conditions through a factorial experiment for the secondary separating part of the self-propelled pepper harvester. Methods: An experimental setup that simulates the secondary separating part of the self-propelled pepper harvester was organized. Test samples were classified into three types according to the number of peppers on a stem, and 12 sets were prepared for each type. Among the operating conditions of the secondary separating part, the rotational speed of drum B (four levels), radial clearance between drums and cylindrical teeth (three levels), and speed ratio between the three drums (two levels) were set as the test factors, and tests were repeated three times for different levels of each factor. The appropriate operating conditions were determined by analyzing the separation ratio and damage ratio of the peppers collected through the secondary separating part. Results: The test factors changed the overall separation ratio and overall damage ratio in similar trends. In other words, the conditions that caused high overall separation ratios also exhibited high overall damage ratios. Owing to the high overall damage ratio in the condition with the highest overall separation ratio, the operating conditions should be selected considering both ratios. Conclusions: When the condition with more than 60% of overall separation ratio and less than 15% of overall damage ratio was considered as the appropriate operating condition, 70 rpm of the rotational speed of drum B, 5 mm of the radial clearance between drums and cylindrical teeth, and 7:3:5 for the speed ratio of the three drums A, B, and C should be applied for the secondary separating part used in this study. Supplementary studies will be required in the future to find optimal operating conditions through the actual field test under further divided test factors.

• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.361-377
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• 1998

The measurement of welding temperature of connector is usually performed with an infra red temperature gauge. However, the factors, which influence the temperature measurement, are rarely known. This research used the welding temperature measurement of the connector as an example, applying the experimental design, in two-phase experiments, to search the affecting factors. In phase-I experiment, we used a resolution III, seven-factor fractional factorial design with two levels for each factor. The result showed that none of the factor was significant in affecting the welding temperature when the type I error ${\alpha}$ was 0.05. Next, we did the phase-II factorial experiment with three factors and each factor had three levels. The experiment showed the experimental time was significant in affecting the temperature measurement when the type I error ${\alpha}$ was 0.05. Further Duncan's multiple range tests on the second experimental data showed that the later the experimental time, the weaker the light intensity could have on the temperature measurement and the average of the highest temperatures was lower. Moreover, the later the experimental time, the smaller was the variance of the temperature measurement and the difference between the averages of the highest and the lowest temperatures was also lower.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.5
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• pp.374-382
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• 2013

Robust design method developed by Genichi Taguchi has been very popular since the 1980s and there have been many academic and applied research works on this topic. However, college students and engineers in companies have had difficulty in understanding the method. This paper presents a procedure to implement the robust design method by an easy-to-execute paper helicopter experiment. A crossed array was adopted, which consists of a resolution IV fractional factorial design with 6 control factors and a factorial design with 3 noise factors. Three performance measures were analyzed; signal-to-noise ratio, mean, and standard deviation of the falling time of the paper helicopter that is to be maximized. Control-noise interaction plots are also given to evaluate the degree of the sensitivity of each level of the control factors to the noise factors. The procedure presented in this paper can be helpful to those who want to have basic knowledge in the robust design method.

• KSBB Journal
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• v.17 no.3
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• pp.228-234
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• 2002

Acetobacter xylinum KJ1 efficiently producing bacterial cellulose(BC) In shaking culture was isolated from a rotten grape. The strain was used to investigate optimum operating conditions for increasing BC production and factorial design model was employed for the optimization. The results of experiments were statistically analyzed by SAS program. Reciprocal effects of each factors(carbon source concentration, shaking speeds(rpm), oxygen pressure, and CSL concentration) and culture condition of BC production were examined by getting regression equation of the dependent variable. Comparisons between experimental results and predicted results about BC concentration were done in total 24 experiments by combination of each factors using SAS program, and the correlation coefficients of BC concentration and BC yield were 0.91 and 0.81, respectively. The agitated cultures were peformed in various operation conditions of factors which affected considerably to BC production in jar fermentor. The results showed that BC concentration was 11.67 g/L in 80 hours cultivation under the condition of carbon source concentration : shaking speeds(rpm) : oxygen pressure : CSL concentration : 4% : 460 rpm : 0.28 : 6%. On the other hand BC yield was 0.42 g/g in 80 hours cultivation under the condition of carbon source concentration : shaking speeds(rpm) : oxygen pressure : CSL concentration : 4% : 564 rpm : 0.21 : 2%. The BC production could be enhanced up to more than 2.4 times by factorial design. The result of a verifying experiment under the optimal conditions determined by the factorial design to the BC production showed that the model was appropriate by obtaining BC concentration of 11.47 g/L in the optimum condition.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.10a
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• pp.855-856
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• 2012

• Corrosion Science and Technology
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• v.21 no.4
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• pp.314-324
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• 2022

The objective of this investigation was to indentify major factors affecting surface roughness among various parameters of electropolishing process using the design of an experiment method (full factorial design) for UNS S31603. Factors selected included electrolyte composition ratio, applied current density, and electrolytic polishing time. They were compared through analysis of variance (ANOVA). Results of ANOVA revealed that all parameters could affect surface roughness, with the influence of electrolyte composition ratio being the highest. As a result of surface analysis after electropolishing, the specimen with the deepest surface damage was about 35 times greater than the condition with the smallest surface damage. The largest value of surface roughness after electropolishing was higher than that of mechanical polishing due to excessive processing. On the other hand, the smallest value of surface roughness after electropolishing was 0.159 ㎛, which was improved by more than 80% compared to the previous mechanical polishing. Taken all results together, it is the most appropriate to perform electrolytic polishing with a sulfuric acid and phosphoric acid ratio of 3:7, an applied current density of 300 mA/cm², and anelectrolytic polishing time of 5 minutes.

• Asia pacific journal of information systems
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• v.25 no.4
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• pp.784-804
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• 2015

This study investigates the effects of a two-sided message on product attitude and purchase intention by using a message structure variable, such as attribute importance in the context of online consumer reviews (OCRs). Study 1 explains the previous inconsistent results of a two-side message by comparing a one-side message and a two-side message by using the attribute importance in negative reviews. Study 2 determines the reasons for the inconsistent results of a refutational two-sided message research by using the attribute importance in negative reviews and website trust. Two experiments are designed to test our hypotheses. The first experiment is a $2{\times}2$ factorial design with 84 participants. The second experiment uses a $2{\times}2{\times}2$ factorial design with 196 participants. In study 1, two-sided OCRs are more credible than one-sided OCRs, and two-sided OCRs that use low important attributes are more effective in making favorable product attitude/purchase intention. In study 2, refutational two-sided OCRs that use high attribute importance render positive effects on product attitudes in trustworthy websites. However, the refutation could negatively affect product attitude/purchase intention in low trustworthy websites.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.3
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• pp.320-327
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• 2017

The main function of an infuser is to ensure constant dosage of a drug. Elastomer drug infusers have been used widely owing to their economic advantages. The mechanism of the device is primarily based on the pressure created from the elastic material that contains the drugs. However, as the drug is infused and the internal pressure is reduced, the drug is not linearly infused at all times. This study involves investigating factors to improve the design of the infuser. The first factor is the range of proper deformation, which does not affect a significant amount of stress variation during infusion. The second is concerned with the flow restrictor and the associated design variables are recommended by employing finite element analysis and the factorial experiment technique. The last factor is related to the spring device connected to balloon. The results showed that the drug reservoir can compensate for unexpected pressure gradient drops.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.9_10 s.146
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• pp.1295-1305
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• 2005

The study was based on a three-stage, non-repetitive factorial experiment in which chemical-rotted kenaf fibers were treated separately with hydrogen peroxide concentrations of $0.5\%,\;1\%\;and\;2\%$, with pH solutions of 7, 9 and 11, and treatment times of 30, 60 and 90 minutes. Under optimal conditions, the study was conducted to determine the bleaching efficiency by the addition of chelators, penetrants and surfactants. The bleaching effects on the kenaf fibers were high in high hydrogen peroxide concentration, high in alkali solution pH, low in long treatment time. The optimal level of hydrogen peroxide on bleaching effects were at $2\%$ hydrogen peroxide concentration, with pH of 11 and treatment time of 60 minutes. Under the conditions of $2\%$ hydrogen peroxide concentration, pH 11 and treatment time of 60 minutes, the addition of chelator: Sodim Pyrophosphate(SP), Citric Acid(CA) made the bleaching effects of the kenaf fibers high.