• Transactions of the Korean Society of Machine Tool Engineers
• /
• v.18 no.2
• /
• pp.170-177
• /
• 2009

The objective of this study is to evaluate an acoustic emission (AE) source characterization and fracture behavior of the SM45C steel by using back-propagation neural network (BPN). In previous research Ref. [8] about k-nearest neighbor classifier (k-NNC) continuity, we used K-means clustering method as an unsupervised learning method for obtaining multi-variate AE main data sets, such as AE counts, energy, amplitude, risetime, duration and counts to peak. Similarly, we applied k-NNC and BPN as a supervised learning method for obtaining multi-variate AE working data sets. According to the error of convergence for determinant criterion Wilk's ${\lambda}$, heuristic criteria D&B(Rij) and Tou values are discussed. As a result, in k-NNC before fracture signal is detected or when fracture signal is detected, showed that produce some empty classes in BPN. And we confirmed that could save trouble in AE signal processing if suitable error of convergence or acceptable encoding error give to BPN.

• Korean Journal of Adult Nursing
• /
• v.24 no.6
• /
• pp.569-579
• /
• 2012

Purpose: The purpose of this study was to investigate the relationship between drug dosage calculation error prevention competence and medication safety organizational climate. Methods: We surveyed 207 nurses from 15 hospitals. An assessment survey was designed to assess the medication safety organizational climate which consisted of four subcategories including medication safety cultures, medication safety initiatives, medication error communication, and medication error management competence. The drug dosage calculation error prevention competence contains two subcategories; Dosage calculation habits and ability. The data were collected from July to August 2011. Descriptive statistics, t-test, ANOVA, partial Pearson correlation coefficient, canonical correlation were used. Results: Organizational climate was related to dosage calculation error prevention competence with two significant canonical variables. The first canonical correlation coefficient was .53 (Wilks' ${\lambda}$=0.71, df=8, p<.001) and that of the second was .21 (Wilks' ${\lambda}$=0.96, df=3, p=.027). The first variate indicated higher perception of medication safety cultures, safety initiatives, error communication and error management competence were related to better dosage calculation habits. The second variate showed higher perception of medication safety cultures and lower medication error management competence were related to higher calculation ability. Conclusion: Continuous supporting strategies for medication safety organizational climate should be implemented to improve drug dosage calculation habits.

• The Korean Journal of Ecology
• /
• v.9 no.3
• /
• pp.135-147
• /
• 1986

The simplification and the searching trends of complex data which assumed relationship between predictor variables and object variables are one of primary objective of ecological research. This study was aimed to apply cononical analysis consisting of canonical correlation analysis and canonical variate analysis related to lichen vegetation and several environmental variables which are elevation, height on grond, exposure side and cover values. Data collected from the Duckyoo National Park in August 1985. Lichen species was ranked by eqivocation information theory with cover values. Canonical correlation analysis was applied to one data set both set both environmental variables and lichem family. In order to make two sets of data matrix the scale of position vector ordination was calculated from the vector scalar product for lichen species. Canonical variate analysis was applied to rearranged data which was made by interval class code for environmental variables. The sharpness values was calculated in frequency of cotingency tables and the dispersion profiles of each species in classes of environmental variables was designed to extract component values based on the decomposition of expected frequencies in contingency table. The results of canonical correlation analysis revealed canonical first correlation value 0.815(89%), and second correlation value 0.083(11%). Significance test showed that the hypothesis of joint mutuallity of canonical correlation is accepted (P>0.05). The relation between canonical score of vegetation variables and that of environmental variable indicated linear tendency.

• The Journal of Korean Society for School & Community Health Education
• /
• v.15 no.1
• /
• pp.31-43
• /
• 2014

Objectives: The purpose of this study is to identify the relationship of personal hygiene education and hand-washing practices among adolescents. Then the impact of such factors on the hand-washing practices was analyzed. Methods: The data of the 2012 Youth Health Risk Behavior web-based Survey collected by Korean Center for Disease Control was analyzed using SPSS. Total 74,186 of middle and hish school students were included. Uni-variate analysis was done by complex sample crosstabs and multi-variate analysis was done by complex sample logistic regression. Results: The 26.8% of students experienced personal hygiene education. The students of boys, low school grade, coeducation, metropolitan, high school record and high economic status experienced more hygiene education. The hand-washing practices were high in the students with the experience of personal hygiene education. In the factors affecting the hand-washing practice, the experience of personal hygiene education was consistently significant. If students experienced the personal hygiene education, they showed 20~30% more rates of hand-washing practices. Conclusions: Hand-washing practice was high when experiencing personal hygiene education. The personal hygiene education was necessary to improve the rate of hand-washing practices.

• Structural Monitoring and Maintenance
• /
• v.7 no.4
• /
• pp.283-294
• /
• 2020

In this paper, an adaptive MEMD based modal identification technique for linear time-invariant systems is proposed employing multiple vibration measurements. Traditional empirical mode decomposition (EMD) suffers from mode-mixing during sifting operations to identify intrinsic mode functions (IMF). MEMD performs better in this context as it considers multi-channel data and projects them into a n-dimensional hypercube to evaluate the IMFs. Using this technique, modal parameters of the structural system are identified. It is observed that MEMD has superior performance compared to its traditional counterpart. However, it still suffers from mild mode-mixing in higher modes where the energy contents are low. To avoid this problem, an adaptive filtering scheme is proposed to decompose the interfering modes. The Proposed modified scheme is then applied to vibrations of a reinforced concrete road bridge. Results presented in this study show that the proposed MEMD based approach coupled with the filtering technique can effectively identify the parameters of the dominant modes present in the structural response with a significant level of accuracy.

• Communications for Statistical Applications and Methods
• /
• v.17 no.3
• /
• pp.391-411
• /
• 2010

For estimating the mean of a finite population, three classes of estimators using multi-auxiliary information with unknown means using two phase sampling in presence of non-response have been proposed with their properties. Asymptotically optimum estimator(AOE) in each class has been identified along with their mean squared error formulae. An empirical study is also given.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.8
• /
• pp.4881-4894
• /
• 2014

This study selected 83 manufacturing firms that had been delisted from the KOSDAQ market from 2009 to 2012 and the sample firms for the two-paired sampling method were compared with 83 normal firms running businesses with same items or in same industry. The 75 financial ratios for five years immediately before delisting were used for Mean Difference Analysis with those of normal firms. Fifteen variables assumed to be significant variables for five consecutive years out of the analysis were used to in the Dichotomous Classification Technique, Logistic Regression Analysis and Discriminant Analysis. As a result of those three analyses, the Logistic Regression Analysis model was found to show the greatest discrimination. This study is differentiated from previous studies as it assumed that the firm's failure proceeded slowly over long period of time and it tried to predict the firm's failure earlier using the five years' historical data immediately before failure, whereas previous studies predicted it using three years' data only. This study is also differentiated from the proceeding comparative studies by its statistically complex Multi-Variate Analysis and Dichotomous Classification Analysis, which general stakeholders can easily approach.

• Health Policy and Management
• /
• v.27 no.4
• /
• pp.315-323
• /
• 2017

Background: This study was purposed to analyze the effect of spatial accessibility to the psychiatry department in general hospital on the outpatient visit of mental patients. Methods: Data was provided from the Statistics Korea and Statistical Geographic Information Service, National Health Insurance Service, Health Insurance Review and Assessment Service, and Korea Transport Institute in 2015. The study regions were 103 administrative regions such as Si and Gu. The 103 regions had at least one general hospitals with a psychiatry department. The number of outpatient visit of mental patients in regions was used as the dependent variable. Spatial accessibility to mental general hospital was used as the independent variable. Control variables included such as demographic, economic, and health medical factors. This study used network analysis and multi-variate regression analysis. Network analysis by ArcGIS ver. 10.0 (ESRI, Redlands, CA, USA) was used to evaluate the average travel time and travel distance in Korea. Multi-variate regression analysis was conducted by SAS ver. 9.4 (SAS Institute Inc., Cary, NC, USA). Results: Travel distance and time had significant effects on the number of outpatient visits in mental patients in general hospital. Average travel time and travel distance had negative effects on the number of visits. Variables such as (number of total population, percentage of aged population over 65, and number of mental general hospital) had significant effects on the number of visit in mental patients. Conclusion: Health policy makers will need to consider the spatial accessibility to the mental healthcare organization in conducting regional health planning.

• Communications for Statistical Applications and Methods
• /
• v.10 no.3
• /
• pp.765-777
• /
• 2003

In this paper, we investigate some measures as tests of multivariate normality based on principal components. The idea was proposed by Srivastava and Hui(1987). They generalized Shapiro-Wilk statistic for multi variate cases. We show the null distributions of the statistics do not depend on the unknown parameters and mention the asymptotic null distributions. Also power performance of the tests are assessed in a Monte Carlo study.

• Journal of the Korean Data and Information Science Society
• /
• v.14 no.4
• /
• pp.1091-1102
• /
• 2003

The Weibull variate is commonly used as a lifetime distribution in reliability applications. Estimation of parameters is revisited in the two-parameter Weibull distribution. The method of product spacings, the method of quantile estimates and the method of least squares are applied to this distribution. A comparative study between a simple minded estimate, the maximum likelihood estimate, the product spacings estimate, the quantile estimate, the least squares estimate, and the adjusted least squares estimate is presented.