• 품질경영학회지
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• 제32권3호
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• pp.109-125
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• 2004

This paper deals with an optimal process control problem in production of hull structural steel plate with high defective rate. The main quality characteristic(dependent variable) is the internal quality(defect) of plates and is dependent on process parameters(independent variables). The dependent variable(quality characteristics) has three categorical ordinal data and there are 35 independent variables(29 continuous variables and 6 categorical variables). In this paper, we determine the main factors and to develop the mathematical model between internal quality predicted probabilities and the main factors. Secondly, we find out the optimal process condition of main factors through analysis of variance(ANOVA) using simulation. We consider three models to obtain the main factors and the optimal process condition: linear, quadratic, error models.

• 한국기계가공학회지
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• 제12권4호
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• pp.87-92
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• 2013

In this study, we carried out the turning of plastic mold steel(STAVAX) with whisker reinforced ceramic tool(WA1) and analyzed ANOVA(Analysis of Variance) test. Multi-regression analysis was performed to find influential factors to surface roughness and to derive regression equation. Results are follows: From ANOVA test and confidence interval analysis of surface roughness, We found that influential factors to surface roughness was feed rate, cutting speed and depth of cut in order. From multi-regression analysis, we derived regression equation of STAVAX. it's coefficient of determination($R^2$) was 0.945 and It means that regression equation is significant. From experimental verification, we confirmed that surface roughness was predictable by regression equation. Compared with former research, we confirmed that increase of feed rate is the main cause of the growing of surface roughness and cutting force.

• 한국의류학회지
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• 제22권1호
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• pp.159-169
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• 1998

The purpose of this study was to develop a large representative data base of market information for jeans apparel. This study was to observe consumer buying behavior and to determine the market share of various brands depending on several variables such as age and distribution regions. This study also analyzed the major factors in purchasing jeans for 17-29 age groups. The 660 questionnaires were distributed and 618 reliable ones were used for statistical analysis. A SAS statistical package including frequency' table, Chi-square test, factor analysis, analysis of variance(ANOVA), Duncan's multiple range test was used. The results of this study showed that consumer possessed about 6 pairs of jeans and bought about 3 pairs of jeans per year. The most recently purchased brand was Nix. Lots of brands were statistically significant at the segmented three age groups and in the five different distribution regions. The most popular type of design was the basic style. The result of factor analysis indicated 4 factors(quality/comfort, famous brand/fashion, mood/extrinsic attitude, economy). The result of ANOVA represented that three factors among them have influenced on the preferred design types.

• 한국의류학회지
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• 제33권10호
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• pp.1673-1682
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• 2009

The purpose of the study was to investigate differences in: 1) importance of buying motives including external stimuli and sales promotional stimuli among groups according to levels of diversity orientation; 2) importance of buying motives including external stimuli and sales promotional stimuli among their subordinate factors. Questionnaires were distributed 340 women who aged between 20 and 30. A sample of 317 women responded to the questionnaire. Using SPSS/PC version 12.0, factor analysis reliability analysis, Analysis of Variance (ANOVA), and Repeated measure ANOVA were used for the data analysis. As results, there were significant differences in importance of buying motives including external stimuli and sales promotional stimuli among groups according to levels of diversity orientation. Also, there were significant differences in importance of external stimuli and sales promotional stimuli among their subordinate factors.

• 한국생산제조학회지
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• 제19권2호
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• pp.184-190
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• 2010

Recently, the polishing process using magnetorheological fluids(MR fluids) has been focused as a new ultra-precision polishing technology for micro and optical parts such as aspheric lenses, etc. This method uses MR fluid as a polishing media which contains required micro abrasives. In the MR polishing process, the surface roughness and material removal rate of a workpiece are affected by the process parameters, such as the properties of used nonmagnetic abrasives(particle material, size, aspect ratio and density, etc.), rotating wheel speed, imposed magnetic flux density and feed rate, etc. The objective of this research is to predict MRR according to the polishing conditions based on the multiple regression analysis. Three polishing parameters such as wheel speed, feed rates and current value were optimized. For experimental works, an orthogonal array L27(313) was used based on DOE(Design of Experiments), and ANOVA(Analysis of Variance) was carried out. Finally, it was possible to recognize that the sequence of the factors affecting MRR correspond to feed rate, current and wheel speed, and to determine a combination of optimal polishing conditions.

• 자원환경지질
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• 제53권2호
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• pp.167-181
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• 2020

본 연구에서는 단층핵의 각력(≥4.75 mm) 함량에 따라 각각 5 wt.% (Case-I), 10 wt.% (Case-II) 및 15 wt.%(Case-III) 단위로 전단강도(최대 전단강도)에 대한 모집단을 분류한 후, 각 Case에 대한 분산분석(ANOVA, analysis of variance)과 다중비교분석(multiple comparison analysis)을 수행하였다. 각 수직응력(54 kPa, 108 kPa, 162 kPa)에서 모집단별로 전단강도의 평균과 표준편차를 계산하고, 전단강도의 분산에 통계적으로 유사한 영향을 미치는 각력 함량을 그룹화함으로써 각력 함량과 전단강도 사이의 관계를 정량적으로 분류하였다. 분석 결과, 전단강도는 각력 함량을 15 wt.% 단위로 범주화한 Case-III에서 집단 1(각력 함량 0~15 wt.%)과 집단 2,3(각력 함량 15~30 wt.%와 30 wt.% 이상)으로 명확하게 분류되었다. Case-III의 각력 함량 15 wt.%에서 분류 기준이 되는 전단강도를 산정한 결과, 수직응력별(54 kPa, 108 kPa, 162 kPa)로 각각 43.6 kPa, 77.6 kPa, 118.6 kPa로 산정되었다. 이 결과를 바탕으로 점착력과 내부마찰각의 분포 범위를 산정한 결과, 점착력의 분포 범위는 각력 함량 15 wt.% 이하에서 0~43.6 kPa, 15 wt.% 이상에서 0~70.0 kPa이며, 내부마찰각의 분포 범위는 각력 함량 15 wt.% 이하에서 0~45.7°, 15 wt.% 이상에서 16.7~57.5°로 산정되었다.

• 한국재료학회지
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• 제25권7호
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• pp.322-329
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• 2015

The magnitude of wear should be at a minimum for numerous automobile and aeronautical components. In the current work, composites were prepared by varying the cenosphere content using the conventional stir casting method. A uniform distribution of particles was ensured with the help of scanning electron microscopy (SEM). Three major parameters were chosen from various factors that affect the wear. A wear test was conducted with a pin-on-disc apparatus; the controlling parameters were volume percentages of reinforcement of 5, 10, 15, and 20%, applied loads of 9.8, 29.42, and 49.03 N, and sliding speeds of 1.26, 2.51, and 3.77 m/s. The design of the experiments (DOE) was performed by varying the different influencing parameters using the full factorial method. An analysis of variance (ANOVA) was used to analyze the effects of the parameters on the wear rate. Using regression analysis, a response curve was obtained based on the experimental results. The parameters in the resulting curve were optimized using the Genetic Algorithm (GA). The GA results were compared with those of an alternate efficient algorithm called Neural Networks (NNs).

• Structural Engineering and Mechanics
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• 제86권5호
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• pp.621-633
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• 2023

Stability analysis and support system estimation of the Beheshtabad water transmission tunnel is investigated in this research. A combination approach based on the rock mass rating (RMR) and rock mass quality index (Q) is used for this purpose. In the first step, 40 datasets related to the petrological, structural, hydrological, physical, and mechanical properties of tunnel host rocks are measured in the field and laboratory. Then, RMR, Q, and height of influenced zone above the tunnel roof are computed and sorted into five general groups to analyze the tunnel stability and determine its support system. Accordingly, tunnel stand-up time, rock load, and required support system are estimated for five sorted rock groups. In addition, various empirical relations between RMR and Q i.e., linear, exponential, logarithmic, and power functions are developed using the analysis of variance (ANOVA). Based on the significance level (sig.), determination coefficient (R²) and Fisher-test (F) indices, power and logarithmic equations are proposed as the optimum relations between RMR and Q. To validate the proposed relations, their results are compared with the results of previous similar equations by using the variance account for (VAF), root mean square error (RMSE), mean absolute percentage error (MAPE) and mean absolute error (MAE) indices. Comparison results showed that the accuracy of proposed RMR-Q relations is better than the previous similar relations and their outputs are more consistent with actual data. Therefore, they can be practically utilized in designing the tunneling projects with an acceptable level of accuracy and reliability.

• 대한기계학회논문집A
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• 제24권12호
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• pp.2952-2962
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• 2000

The design of experiment(DOE) is getting more attention in the engineering community since it is easy to understand and apply. Recently, engineering designers are adopting DOE with orthogonal arrays when they want to design products in a discrete design space. In this research, a design flow with orthogonal arrays is defined for structural design according to the general DOE. The design problem is defined as a general structural optimization problem. Sensitivity information is evaluated by the analysis of variance(ANOVA), and an optimum design is determined from analysis of means(ANOM). Interactions between design variables are investigated to achieve additivity which should be valid in DOE. When strong interactions exit, a method is proposed. Some methods to consider the problem are suggested.

• 수산해양교육연구
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• 제29권2호
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• pp.552-559
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• 2017

To assess the effect of LED lights on marine microalgae growth in the laboatory, Tetraselmis suecica, Chaetoceros simplex and Isochrysis galbana were cultured under $20{\pm}1^{\circ}C$, Walne's medium and aeration using 3.6 L glass vessels. The LED light sources were Blue, Red, Blue+Red, CoolWhite and WarmWhite. The experiments were conducted three times. The density of microalgae was shown as the counted number of cells per day, and the specific growth rate was calculated by using the density. The statistical analysis was performed by analysis of variance using the SPSS 20.0 program. T. suecica culture was the highest density under the Blue LED light source, so the light source was the most effective for the growth of this alga. C. simplex and I. galbana culture had the highest density under the Blue+Red LED light source, therefore this light source was the most effective for the growth of these algae. The result of analysis of variance showed significant between groups.