• Environmental Engineering Research
• /
• v.19 no.3
• /
• pp.197-203
• /
• 2014

This study estimated spatial and seasonal variation of water quality to understand characteristics of Nakdong river basin, Korea. All together 11 parameters (discharge, water temperature, dissolved oxygen, 5-day biochemical oxygen demand, chemical oxygen demand, pH, suspended solids, electrical conductivity, total nitrogen, total phosphorus, and total organic carbon) at 22 different sites for the period of 2003-2011 were analyzed using multivariate statistical techniques (cluster analysis, principal component analysis and factor analysis). Hierarchical cluster analysis grouped whole river basin into three zones, i.e., relatively less polluted (LP), medium polluted (MP) and highly polluted (HP) based on similarity of water quality characteristics. The results of factor analysis/principal component analysis explained up to 83.0%, 81.7% and 82.7% of total variance in water quality data of LP, MP, and HP zones, respectively. The rotated components of PCA obtained from factor analysis indicate that the parameters responsible for water quality variations were mainly related to discharge and total pollution loads (non-point pollution source) in LP, MP and HP areas; organic and nutrient pollution in LP and HP zones; and temperature, DO and TN in LP zone. This study demonstrates the usefulness of multivariate statistical techniques for analysis and interpretation of multi-parameter, multi-location and multi-year data sets.

• Journal of dental hygiene science
• /
• v.11 no.2
• /
• pp.63-67
• /
• 2011

This study aimed to propose appropriate methods of statistical analysis and interpretation of survey results in dental hygiene. By using examples of published articles in the Journal of Dental Hygiene Science from 2003 to 2008, we made some suggestions to improve scientific and clear writing of the contents; purpose of the study, subjects and methods, statistical analysis, tables, and interpretations.

• 한국석유지질학회:학술대회논문집
• /
• spring
• /
• pp.10-14
• /
• 1998

A systematic methodology is developed for the electrofacies determination from wireline log data using multivariate statistical analysis. To consider corresponding contribution of each log and reduce the computational dimension, multivariate logs are transformed into a single variable through principal components analysis. Resultant principal components logs are segmented using the statistical zonation method to enhance the efficiency and quality of the interpreted results. Hierarchical cluster analysis is then used to group the segments into electrofacies. Optimal number of groups is determined on the basis of the ratio of within-group variance to total variance and core data. This technique is applied to the wells in the Korea Continental Shelf. The results of field application demonstrate that the prediction of lithology based on the electrofacies classification matches well to the core and the cutting data with high reliability This methodology for electrofacies classification can be used to define the reservoir characteristics which are helpful to the reservoir management.

• Journal of Environmental Science International
• /
• v.17 no.4
• /
• pp.405-412
• /
• 2008

Statistical analysis technique was applied to operating parameters and removal efficiency data sets obtained from advanced wastewater treatment plant during 1 year. Through factor analysis three factors derived varimax rotation were selected each plant. Three components explained 96%, 87% of the total variance of the process, respectively. The components on $A_2O$ Plant were identified in the following order : 1) Shortening the SRT during high-flow period, 2) Keeping biomass high on winter 3) factor was related to DO. On DNR plant, we defined them as follows: factor 1, Prolonged the SRT during high-flow period; factor 2 was related to sludge return; factor 3, Influent BOD during low-DO period. This technique was believed to assist operators in identifying priorities to improve operation efficiency.

• Journal of the Korean Statistical Society
• /
• v.30 no.2
• /
• pp.193-217
• /
• 2001

Despite of the rich literature in discriminant analysis, this complicated subject remains much to be explored. In this article, we study the theoretical foundation that supports Fisher's linear discriminant analysis (LDA) by setting up the classification problem under the dimension reduction framework as in Li(1991) for introducing sliced inverse regression(SIR). Through the connection between SIR and LDA, our theory helps identify sources of strength and weakness in using CRIMCOORDS(Gnanadesikan 1977) as a graphical tool for displaying group separation patterns. This connection also leads to several ways of generalizing LDA for better exploration and exploitation of nonlinear data patterns.

• Communications for Statistical Applications and Methods
• /
• v.22 no.3
• /
• pp.265-276
• /
• 2015

In this paper, we propose hierarchical cluster analysis and multidimensional scaling for joint distribution valued data. Information technology is increasing the necessity of statistical methods for large and complex data. Symbolic Data Analysis (SDA) is an attractive framework for the data. In SDA, target objects are typically represented by aggregated data. Most methods on SDA deal with objects represented as intervals and histograms. However, those methods cannot consider information among variables including correlation. In addition, objects represented as a joint distribution can contain information among variables. Therefore, we focus on methods for joint distribution valued data. We expanded the two well-known exploratory methods using the dissimilarities adopted Hall Type relative projection index among joint distribution valued data. We show a simulation study and an actual example of proposed methods.

• Korean Journal of Human Ecology
• /
• v.14 no.1
• /
• pp.47-57
• /
• 2005

We conducted a content analysis of the researches published for a 7-year period (1997-2003) in the Korean Journal of Play Therapy (Korean Association for Play Therapy) and The Journal of Play Therapy (Korean Association of Psychological Rehabilitation for Children). Specifically, we analyzed a total of 156 articles for research contents, instruments, subjects, statistical analytic methods, and references. The results of the study are as follows: First, the principal areas of research activity and publication were specific theoretical review, personality, and adjustment research. Most outcomes, processes, and outcome researches were conducted in a form of case study. Second, typical samples contained 4 to 6 year old children or elementary schoolers. A lot of them were counseling center clients or normally adapted children. Third, 37% of the articles used ANOVA-related statistical analytic methods, and 35% of them used descriptive statistical analytic methods. Lastly, many articles averagely cited foreign references written 11 years prior to domestic references.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.501-504
• /
• 2001

The use of error compensation techniques has been recognized as an effective way in the improvement of the accuracy of a machine tool. The laser measurement method for identifying position errors of machine tool has the disadvantages such as high cost, long calibration time and usage of volumetric error synthesis model. Accordingly, this paper deals with analysis of the position errors of a machine tool using ball bar test without using complicated error synthesis model. Statistical analysis method was adopted in this paper for deriving position errors using hemispherical helix ball bar test.

• Journal of the Korean Society of Safety
• /
• v.26 no.2
• /
• pp.83-88
• /
• 2011

Annually, many parts of the Korea have been damaged from the localized heavy rain and/or typhoons which peak between June and September, which result in extensive financial and human loss. Especially, because the most area of Gangwon province is composed of the steep slope mountains, the damages by the debris flow or land-sliding are more frequent and the frequency has been increased. To analyze the characteristics and causes of these debris flow disasters, lots of study are recently being conducted through database of weather, hydrologic, soil etc using a GIS or remote sensing. In this study, we applied GIS method to analyze the risk of the debris flow area. With the statistical analysis and infinite slope stability model(SINMAP), the debris flow risk level of the mountain slope was generated. As a result, the GIS statistical analysis showed high correlation that former model of SINMAP in determining the debris flow risk area.

• Journal of the Korean Society of Safety
• /
• v.11 no.3
• /
• pp.168-176
• /
• 1996

Statistical analysis of occupational accidents plays an important role in establishing measures against accidents and for evaluating safety performance in work places. This research work, numerous numbers of research work have been conducted, which attemped to verify the existence of !he concept of "accident proneness" Also researches have been developed in the fields of systems safety analysis and risk analysis to analyze the characteristics of occupational accidents. This paper presents a brief historical review of these research activities with particular emphasis on the statistical analysis of occupational accidents. Based on this review, further development needs in relation to the statistical research on the occupational accidents in the near future are discussed.discussed.