• Journal of the Korean Society of Manufacturing Process Engineers
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• v.3 no.4
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• pp.13-19
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• 2004

This paper deals with the analysis of geometric error and the optimization of process parameters in surface grinding. Taguchi method which is one of the design of experiments has been introduced in achieving the aims. The process parameters were the grain size, the wheel speed, the depth of cut and the table speed. The effect of the process parameters on the geometric error was examined and an optimal set of the parameters was selected to minimize the geometric error within the controllable range of the used grinding machine. The reliability of the results was evaluated by the ANOVA.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.281-287
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• 2006

Maintaining adequate chlorine residual is crucial in water treatment facilities, Treatment technique, newly promulgated regulation, requires sufficient disinfection in order to control more resistant microorganisms such as Viruses and Giardia lamblia. Each water treatment plant should report various water qualities including chlorine residual and disinfection by-products, thus plenty of data has been generated. Even though statistical analysis using these data are forced to investigate the status and effect of water qualities in water facilities very few researches have been performed in korea. This study performed statistical analysis of chlorine residual during three years in Korean drinking water. The average chlorine residual concentrations were 0.701mg/L, 0.738mg/L, 0.763mg/L in 2002, 2003, 2004, respectively. Monthly variations of chlorine residual was not significant. ANOVA result showed that yearly variance of chlorine residual is different in only less than $5000m^3/day$ of water treatment capacity. The statistical analysis can help government to establish new regulation with scientific basis.

• Journal of the Korean Data and Information Science Society
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• v.27 no.6
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• pp.1565-1571
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• 2016

This paper is an empirical study of chinese consumers' lifestyle by country of origin effect of mobile phone. The data we analyze in this paper was collected and studied in Kim et al. (2006, 2007). We classify the respondents into the four groups according to the responses of country of origin effect of mobile phone. The four groups are group K (preference in made in Korea), group J (preference in made in Japan), group U (preference in made in USA), and group C (preference in made in China). One-way ANOVA and stepwise discriminant analysis are applied to classify the training sample which consists of 89 lifestyle variables and two personnel information. It is observed that group K is more open-minded, out front, aggressive, and self-assertive compared to group C.

• Journal of Navigation and Port Research
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• v.32 no.10
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• pp.751-757
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• 2008

This paper made some statistical analyses on marine accidents in Korean waters using marine accident statistics. They were verified through analyses of one-way ANOVA: the difference in average number of marine accidents among Korean waters, between fishing and non-fishing vessels, and by year and by month The pairwise post hoc multiple comparisons of REGW-For GH test were additionally tested. As a result, there were significance differences among Korean waters. The difference of marine accidents by year was verified to have a statistical significance in the South and the East Sea for the fishing vessel, and in the South Sea for the non-fishing vessel. There were signifiant differences of monthly marine accidents by month in the Yellow and the East Sea for the fishing vessel only.

• Transactions of the Korean hydrogen and new energy society
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• v.34 no.6
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• pp.712-721
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• 2023

While hydrogen is widely used, it has a low minimum ignition energy, raising safety concerns when using it. This research studied which parameters are the key variables in the hydrogen release and diffusion. These parameters were divided into six process variables in the initial release and two environmental variables in the dispersion. One hundred and twenty cases were selected through design of experiment, and the end-point in each case were analyzed using PHAST. Afterwards, an end-point prediction model was developed using RSM and ANOVA, and the impact of each variable on the endpoint was analyzed. As a result, the influence of eight variables was graded. The nozzle diameter had the greatest influence on the end-point, while the pipe roughness coefficient had no effect on the end-point. It is expected that these results will be used as basic data to improve safety across all fields of hydrogen handling facilities.

• The Korean Journal of Applied Statistics
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• v.24 no.2
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• pp.373-381
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• 2011

This paper discusses how to get the sums of squares due to treatment factors when Type I Analysis is used by projections for the analysis of data under the assumption of a two-way ANOVA model. The suggested method does not need to calculate the residual sums of squares for the calculation of sums of squares. There-fore, the calculation is easier and faster than classical ANOVA methods. It also discusses how eigenvectors and eigenvalues of the projection matrices can be used to get the calculation of sums of squares. An example is given to illustrate the calculation procedure by projections for unbalanced data.

• Journal of agriculture & life science
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• v.46 no.4
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• pp.21-30
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• 2012

The objective of this study was to comprehend inter-species association and factors affecting species composition by factor analysis and to classify forest types of natural forests in Dootasan. We examined the correlation (positive or negative) of the major species by correlation analysis, the selection of three factors affecting the species composition by factor analysis, cluster analysis on the basis of factor scores, and the evaluation of the results of forest type classification by ANOVA. The outputs of correlation analysis were closely associated with those of factor analysis. The first factor affecting species composition was found to be the decline phenomenon of Pinus densiflora during forest succession process. The second and third factors were growth environments in valley and slope, respectively. The cluster analysis was carried out based on three factors affecting the species composition. The results indicated that the study area was classified into four forest types as follows: Quercus mogolica-Acer mono-Fraxinus rhynchophylla community, Q. mongolica community, Q. mongolica-Tilia amunrensis community and Pinus densiflora community. The dominant species of each community in the four classified forest types were significantly different (p<0.05).

• Journal of Korean Society of Forest Science
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• v.97 no.6
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• pp.565-569
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• 2008

Geographic variation of characteristics of cone, seed and bract morphology were examined in 8 populations of rare endemic Abies nephrolepis (Trautv.) Maxim and A. koreana Wilson. Additionally we studied classification index to distinguish between the species by the method of discriminant analysis. Nested ANOVA showed that there were statistically significant differences among populations as well as among individuals within populations in all 13 morphological traits. In the seed length, seed index, bract width, and bract index of A. nephrolepis and the bract width and index of A. koreana, variance components among populations were larger than those among individuals within populations. In discriminant analysis, three traits (cone width, length of seed wing, and bract length) were found to be useful in discriminating A. nephrolepis from A. koreana. The optimal classification results of stepwise selection were discriminated length of seed wing and bract length.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.285-292
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• 2022

The objective of this study is to investigate whether CGS generated in IGCC satisfies the fine aggregate quality items specified in KS F 2527(Concrete Aggregate) through the pretreatment process system and the quality improvement the system. The statistical significance of the pretreatment process was analyzed through Repeated Measurements ANOVA as measured values according to individually pretreatment process system. As a result of the analysis, In the case of CGS fine aggregate quality before and after the pretreatment process system, the density increased 5.2 %, the absorption rate decreased by 1.86 %, the 0.08 mm passing ratio decreased by 2.25 %, and Fineness Modulus and Particle-size Distribution were also found to be adjustable. It was found that the pretreatment process system was significant in improving the quality of CGS.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.339-345
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• 2020

In the field of defense, one-shot devices such as missiles are stored for a long period of time after they are manufactured, so it is essential to predict their storage life. A study was conducted to find the shelf life of a Li-ion battery used in one-shot devices. To do this, a Li-ion battery that has been used in weapon systems for more than 5 years was secured. A non-functional test was performed on the battery to check for external changes or failures. After the non-functional test, a discharge test was performed to measure the performance after storing it. Through the test, the performance was checked, including the initial charging voltage, discharge time, and battery temperature, and the trend of the change was identified. An F-test, One-way ANOVA, and regression analysis were performed to verify the aging, and the shelf life of the battery was estimated by an approximation formula that was derived through a regression analysis. As a result of the ANOVA, the p-value was less than the reference value of 0.05, and the performance of the battery decreased by more than 15% after a certain period of time. This change is assumed to result from the change in physical properties of the lithium polymer cell.