• Journal of the Korean Society of Safety
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• v.25 no.2
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• pp.78-83
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• 2010

An installation of automated speed enforcement system(ASES) was known for traffic safety and accident preventive effects that traffic characteristics transmute by speed distribution stabilizing. This study is verified the variations of average speed, 85% speed, speed distribution and dispersion as traffic characteristics depend on enforcement system influences in the road. We tested selected 5 areas. By and large, it has a little differences depend on road geometric structure and traffic environment but that is not too much. After all, after automated speed enforcement system installed in all of test areas, average speed, 85% accumulated speed, speed distribution and dispersion characteristics were declined and equalized. The speed dispersion was smaller than before installed the ASES. The speed dispersion value of each case that is the limited speed has been 70Km/h, 80Km/h at flat and straight, 80Km/h at downhill and straight or downhill and left-curved area was 77.3%, 65.2%, 68.7% and 54.1%. Each of the data was declined. We could analyze that average speed distributed depletion factor was declined rapidly by 66.3% in test area.

• 대한공업교육학회지
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• v.31 no.2
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• pp.350-363
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• 2006

Recently, the micro end-milling processing is demanded the high-precise technique with good surface roughness and rapid time in milli-structure parts, micro machine parts and molding industry. The cutting conditions of micro end-milling has an effect on surface roughness of cutting surface. Therefore this study was carried out to cut stainless steel using high revolution air bearing spindle and micro end-mill and analyze the cutting condition to get the optimum surface roughness by design of experiment. From this study, surface roughness have an much effect according to priority on depth of cut, revolution of spindle and feed.

• The Korean Journal of Applied Statistics
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• v.28 no.2
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• pp.151-158
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• 2015

This paper discusses how to use projections for the analysis of data from balanced incomplete block designs. A model is suggested as a matrix form for the interblock analysis. A second set of treatment effects can be found by projections from the suggested interblock model. The variance and covariance matrix of two estimated vectors of treatment effects is derived. The uncorrelation of two estimated vectors can be verified from their covaraince structure. The fitting constants method is employed for the calculation of block sum of squares adjusted for treatment effects.

• Korean Journal of Applied Biomechanics
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• v.28 no.2
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• pp.127-134
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• 2018

Objective: In a statistical linear model estimating the center of rotation of a human hip joint, which is the parameter related to the mean of response vectors, assumptions of homoscedasticity and independence of position vectors measured repeatedly over time in the model result in an inefficient parameter. We, therefore, should take into account the variance-covariance structure of longitudinal responses. The purpose of this study was to estimate the efficient center of rotation vector of the hip joint by using covariance pattern models. Method: The covariance pattern models are used to model various kinds of covariance matrices of error vectors to take into account longitudinal data. The data acquired from functional motions to estimate hip joint center were applied to the models. Results: The results showed that the data were better fitted using various covariance pattern models than the general linear model assuming homoscedasticity and independence. Conclusion: The estimated joint centers of the covariance pattern models showed slight differences from those of the general linear model. The estimated standard errors of the joint center for covariance pattern models showed a large difference with those of the general linear model.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.10
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• pp.2150-2158
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• 2002

A recent research and development has the requirement for the optimization to shorten design time of modified or new product model and to obtain more precise engineering solution. General optimization problem must consider many conflicted objective functions simultaneously. Multi-objective optimization treats the multiple objective functions and constraints with design change. But, real engineering problem doesn't describe accurate constraint and objective function owing to the limit of representation. Therefore this study applies variance analysis on the basis of structure analysis and DOE to the vertical roller mill fur portland cement and proposed statistical design model to evaluate the effect of structural modification with design change by performing practical multi-objective optimization considering mass, stress and deflection.

• Human Ecology Research
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• v.57 no.3
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• pp.315-328
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• 2019

This study examined the mediating effect of self-esteem in the relationship between maternal rejective parenting attitude and children's leadership as well as identified gender differences in the mediating pathways. The mediating effects of this study were examined after controlling the effect of maternal employment status on rejection parenting attitude and the effect of siblings on the children's leadership. Participants consisted of 330 five- and six-year-old children (151 boys and 179 girls) and their mothers. Data analyses included t-tests, F tests, $Scheff{\acute{e}}$ post-hoc tests and Pearson's correlation. Structure equation modeling examined the mediating effect of self-esteem. Bootstrapping method was applied to examine the significance of the mediating effects. Gender differences in the mediating effect were examined through multiple group path analyses. The results of this study were as follows. First, self-esteem mediated the relationship between the maternal rejective parenting attitude on children's leadership. Second, there was a significant gender difference in the mediating pathways with a full mediating effect of self-esteem for boys; however, there was only a partial mediating effect for the girls. This study has implication for investigating gender difference in the mediating mechanism of explaining variance in the leadership of preschoolers. The limitations and more implications of this study are also discussed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.6
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• pp.98-104
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• 2018

Deflected 4-way panels of ceiling air conditioners produced by injection molding process have caused dew condensation at the edge of products. In order to prevent this drawback with reducing weight and deformation, this study proposed renovated process adopting microcellular foaming. According to results from 2-sample t-test and analysis of variance(ANOVA), the critical factors affecting weight were melt temperature and injection speed. In addition, the vital effects on deformation were structure at the edge, mold temperature and cooling time. Optimal conditions of these parameters were derived by regressive analysis with CAE and response surface method(RSM), and then applied to an actual design and process stage to analyze performance. As a results, it clearly showed that new process improved process capability as well as reduced both weight and deformation by 18.8% and 71.9% respectively compared to the conventional method.

• Journal of Korean Academy of Nursing
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• v.49 no.5
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• pp.643-654
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• 2019

Purpose: The purpose of this study was to develop and psychometrically test the Korean Geriatric Loneliness Scale (KGLS). Methods: The initial items were based on in-depth interviews with 10 older adults. Psychometric testing was then conducted with 322 community-dwelling older adults aged 65 or older. Content, construct, and criterion-related validity, classification in cutoff point, internal consistency reliability, and test-retest reliability were used for the analysis. Results: Exploratory factor analysis showed three factors, including 15 items explaining 91.6% of the total variance. The three distinct factors were loneliness associated with family relationships (34.3%), social loneliness (32.4%), and a lack of belonging (24.9%). As a result of confirmatory factor analysis, 14 items in the three-factor structure were validated. Receiver operating characteristic analysis demonstrated that the KGLS' cutoff point of 32 was associated with a sensitivity of 71.0%, specificity of 80.2%, and area under the curve of .83. Reliability, as verified by the test-retest intraclass correlation coefficient, was .89, and Cronbach's ${\alpha}$ was .90. Conclusion: As its validity and reliability have been verified through various methods, the KGLS can contribute to assessing loneliness in South Korean older adults.

• Communications for Statistical Applications and Methods
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• v.27 no.6
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• pp.701-714
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• 2020

Quantitative high throughput screening (qHTS) assays are used to assess toxicity for many chemicals in a short period by collectively analyzing them at several concentrations. Data are routinely analyzed using nonlinear regression models; however, we propose a new method to analyze qHTS data using a nonlinear mixed effects model. qHTS data are generated by repeating the same experiment several times for each chemical; therefor, they can be viewed as if they are repeated measures data and hence analyzed using a nonlinear mixed effects model which accounts for both intra- and inter-individual variabilities. Furthermore, we apply a one-step approach incorporating robust estimation methods to estimate fixed effect parameters and the variance-covariance structure since outliers or influential observations are not uncommon in qHTS data. The toxicity of chemicals from a qHTS assay is classified based on the significance of a parameter related to the efficacy of the chemicals using the proposed method. We evaluate the performance of the proposed method in terms of power and false discovery rate using simulation studies comparing with one existing method. The proposed method is illustrated using a dataset obtained from the National Toxicology Program.

• Journal of Korean Biological Nursing Science
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• v.24 no.3
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• pp.150-160
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• 2022

Purpose: The current study investigated how clinical microbiology courses are conducted at the undergraduate nursing level in South Korea to identify the perceptions of clinical nurses regarding their knowledge and the clinical importance of microbiology and further assess their educational needs. Methods: Curricula presented on the websites of 202 undergraduate nursing institutions were reviewed. In addition, a survey assessing the knowledge and importance of clinical microbiology perceived by nurses was conducted online. A total of 150 nurses participated in the survey. Data were analyzed using descriptive statistics, correlation coefficients, t-tests, analysis of variance, Borich Needs Assessment Model, and Locus for Focus Model. Results: The results indicated that 90% of undergraduate nursing institutions offer clinical microbiology courses under various subject names. The perceived knowledge and importance of clinical microbiology were correlated; however, knowledge was consistently lower than the perceived importance of clinical biology among nurses. The structure and proliferation of novel viruses ranked highest in the educational needs of nurses based on both the Borich Needs Assessment Model and Locus for Focus Model. Conclusion: Based on the findings, this study suggests educational opportunities for clinical microbiology in hospital settings to reduce discrepancies between knowledge and the importance of clinical microbiology faced by nurses.