• Communications for Statistical Applications and Methods
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• v.23 no.6
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• pp.497-515
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• 2016

Modern processes often monitor more than one quality characteristic that are referred to as multivariate statistical process control (MSPC) procedures. The MSPC is the most rapidly developing sector of statistical process control and increases interest in the simultaneous inspection of several related quality characteristics. Most multivariate detection procedures based on a multi-normality assumptions are independent, but there are many processes that assume non-normality and correlation. Many multivariate control charts have a lack of related joint distribution. Copulas are tool to construct multivariate modelling and formalizing the dependence structure between random variables and applied in several fields. From copula literature review, there are a few copula to apply in MSPC that have multivariate control charts, and represent a successful tool to identify an out-of-control process. This paper presents various types of copulas modelling for the multivariate control chart. The performance measures of the control chart are the average run length (ARL) and the average number of observations to signal (ANOS). Furthermore, a Monte Carlo simulation is shown when the observations were from an exponential distribution.

• International Journal of Highway Engineering
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• v.15 no.3
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• pp.93-101
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• 2013

PURPOSES : This study is to investigate the relationship of socioeconomic characteristics and road network structure with traffic growth patterns. The findings is to be used to tweak traffic forecast provided by traditional four step process using relevant socioeconomic and road network data. METHODS: Comprehensive statistical analysis is used to identify key explanatory variables using historical observations on traffic forecast, actual traffic counts and surrounding environments. Based on statistical results, a multiple regression model is developed to predict the effects of socioeconomic and road network attributes on traffic growth patterns. The validation of the proposed model is also performed using a different set of historical data. RESULTS : The statistical analysis results indicate that several socioeconomic characteristics and road network structure cleary affect the tendency of over- and under-estimation of road traffics. Among them, land use is a key factor which is revealed by a factor that traffic forecast for urban road tends to be under-estimated while rural road traffic prediction is generally over-estimated. The model application suggests that tweaking the traffic forecast using the proposed model can reduce the discrepancies between the predicted and actual traffic counts from 30.4% to 21.9%. CONCLUSIONS : Prediction of road traffic growth patterns based on surrounding socioeconomic and road network attributes can help develop the optimal strategy of road construction plan by enhancing reliability of traffic forecast as well as tendency of traffic growth.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.5
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• pp.912-917
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• 2010

It was known that oil-filled transformer's life depended on insulating paper which was applied to transformers for insulating of transformer. Therefore when paper was aged, its electrical, mechanical and chemical characteristics were changed. Especially if operating temperature was high, paper was quickly damaged. As cellulose paper which was mainly used for solid insulation of transformers was degraded, the cellulose polymer chains broke down into shorter lengths and gases such as CO, $CO_2$, $CH_4$, $C_2H_4$ and so on were produced from paper. Also by-product known as furan compounds were producted from paper and it were dissolved within insulating oil. In this paper accelerating aging cell was aged during 60 hours at 100, 150, 180 and $200^{\circ}C$, respectively, so evaluating the chemical characteristics of cellulose paper by thermal. An it were performed analysis such as tensile strength(TS), dissolved gas analysis(DGA) and high performance liquid chromatography(HPLC). Also for analyzing of correlation between insulating degradation characteristics, it was performed linear regression method as statistical treatment.

• Journal of Technologic Dentistry
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• v.33 no.4
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• pp.529-538
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• 2011

Purpose: The purpose of this study was to investigate the factors affecting turnover and job satisfaction, to reduce turnover rate of dental technician. Methods: Subjects included dental technicians in the metropolitan areas of the cities of Daegu and Gyeong-buk. Surveys were filled out by consenting dental technicians. Statistical analysis was done using the Statistical Package for Social Sciences version 18.0 for Windows. We determined frequencies and percentage, calculating means, and standard deviations, and determining statistical significance using t-tests, analysis of variance. Results: Job satisfaction showed differences in General characteristics associated with gender, age, monthly salaray, education. Turnover intention showed differences in General characteristics associated with age, monthly salaray. Job satisfaction showed differences in dental laboratory characteristics associated with Career, Working time. Turnover intention showed differences in dental laboratory characteristics associated with working time. Conclusion: In order to reduce turnover rate of dental technician, Job satisfaction of dental technicians have to find ways to improve. The comprehensive and reliable research which measures job satisfaction of dental technician is necessary.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.1
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• pp.18-26
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• 2002

With the introduction of Fractal notation, various fields of engineering adopted fractal notation to express characteristics of geometry involved and one of the most frequently applied areas was turbulence. With research on turbulence regarding the surface as fractal geometry, attempts to analyze turbulent premised flame as fractal geometry also attracted attention as a tool for modeling, for the flame surface can be viewed as fractal geometry. Experiments focused on disclosure of flame characteristics by measuring fractal parameters were done by researchers. But robust principle or theory can't be extracted. Only reported modeling efforts using fractal dimension is flame speed model by Gouldin. This model gives good predictions of flame speed in unstrained case but not in highly strained flame condition. In this research, approaches regarding fractal dimension of flame as one representative value is pointed out as a reason for the absence of robust model. And as an extort to establish robust modeling, Presents methods treating fractal dimension as statistical variable. From this approach flame characteristics reported by experiments such as Da effect on flame structure can be seen quantitatively and shows possibility of flame modeling using fractal parameters with statistical method. From this result more quantitative model can be derived.

• Proceedings of the Korea Concrete Institute Conference
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• 1990.04a
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• pp.90-95
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• 1990

It is widely recognized that the strengths of reinforced concrete members have random characteristics due to the variability of the mechanical properties of concrete and steel, the dimensional error as well as incorrect placement of reinforcing bars. Statistical models of the variabilities of strengths of reinforced concrete members, therefore, need to be developed to evaluate the safety level implied in current practices. Based on the probabilistic models of basic factors affecting the R.C. member strengths, in this study, the probabilistic characteristics of member resistance have been studied through Monte Carlo simulation.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.507-510
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• 1998

Performance of AMLCD pixels depends on the electrical characteristics of thin film transistor switches. The high quality of LCD can be obtained by minimizing the process and device variations of TFT. The effect of process and device factors on poly-Si TFT characteristics are calculated by ATHENA and ATLAS, and the optimized design windows based on statistical design of experiment are suggested for high performance 20 inch LCD are suggested for high performance 20 inch LCD monitors.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.113-118
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• 2002

Vibrational characteristics of coupled beam ＆ plate system are considered on simple system, which consists of plates(2-subsystem) and beams(4-subsystem), using experimental statistical energy analysis(ESEA). First, damping and coupling loss factors of the system are determined by power injection method (PIM). Then, energy distribution of all the subsystem is estimated from the power balance equation. Finally, these quantities are compared with measured energy. The correlation of measured and estimated results for the sample problem is reasonably good.

• Journal of Elementary Mathematics Education in Korea
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• v.21 no.2
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• pp.391-414
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• 2017

The purpose of this study is to find the correlation between the level of 6th graders' achievement level in Probability and Statistics education, which were proposed in the curriculum, which targeted the 6th graders in the elementary school, and statistical literacy. For this, first, questions asking the achievement level in the probability and statistics(Part A), and questions asking the statistical literacy(Part B), were used to study the achievement level of the students. Second, the achievement level in the probability and statistics, and the statistical literacy were measured. In order to achieve the purpose of this study, questionnaire that consists of 10 questions was invented. The questionnaire was divided into Part 1 and Part 2 under the consideration upon the characteristics of the questions. The results of the questionnaires given to the students were classified into "high, medium, and low" and were separated into 7 categories. Results of comparing category 3 and category 6, which have shown opposing tendencies, we could find that students who are good at school mathematics and students with high statistical literacy have respective and different characteristics. For actually effective statistical education, consideration upon and reflection of core aspects such as intuition and critical thinking in the curriculum are needed.

• The Journal of the Acoustical Society of Korea
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• v.8 no.1
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• pp.5-12
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• 1989

This paper is concerned with the characteristics on the statistical parameters of vibration signal from bearing with changing its operating conditions as well as the spreading of faults. The rms, Kurtosis, crest factor, probability of exceedance and probability density function have been chose as the statistical parameters. To characterize of each, vibration signals have been recorded from four ball tester at different loads, operation speeds and time. The values of the statistical parameters for each frequency band have been calculated after A/D conversion and digital filtering of the recorded signals. It has been found that unlike rms values the statistical parameters such as Kurtosis etc. are almost unchanging with the change of the operating conditions such as load and speed. This suggests that the statistical parameters may be used for determining the development of faults independent of the operating conditions. In fact, the statistical parameters deviate considerably from their respective normal values when the faults developed under load conditions in the samples, conforming the suggestion.