• The Korean Journal of Applied Statistics
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• v.26 no.6
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• pp.987-998
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• 2013

This paper considers the statistical characteristics on the air quality (PM10) of Korea collected hourly in 2011. PM10 in Korea exhibits very strong correlations even for higher lags, namely, long range dependence. It is power-law tailed in marginal distribution, and generalized Pareto distribution successfully captures the thicker tail than log-normal distribution. However, slowly decaying autocorrelations may confuse practitioners since a non-stationary model (such as changes in mean) can produce spurious long term correlations for finite samples. We conduct a statistical testing procedure to distinguish two models and argue that the high persistency can be explained by non-stationary changes in mean model rather than long range dependent time series models.

• The Korean Journal of Applied Statistics
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• v.29 no.2
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• pp.301-308
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• 2016

The process capability index is used to determine whether a production process is capable of producing items within a specified tolerance. Some process capability indices $C_p$, $C_{pk}$ and $C_{pm}$ have been of particular interest as useful management tools for tracking process performance. Most evaluations on process capability indices focus on statistical estimation and test of hypothesis. It is necessary to investigate their asymptotic correlationship among basic estimators ${\hat{C}}_p$, ${\hat{C}}_{pk}$ and ${\hat{C}}_{pm}$ of process capability indices $C_p$, $C_{pk}$ and $C_{pm}$. In this paper, we study their asymptotic correlationship for three process capability indices ${\hat{C}}_p$, ${\hat{C}}_{pk}$ and ${\hat{C}}_{pm}$ under bivariate normal distribution BN(${\mu}_x,{\mu}_y,{\sigma}^2_x,{\sigma}^2_y,{\rho}$). With some nonnormal processes, the asymptotic correlation coefficient of any two respective process capability index estimators could be established.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.6
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• pp.212-217
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• 2020

The purpose of this study was to analyze the volatility and properties of a time series for tangerine prices in Jeju using the GARCH model of Bollerslev(1986). First, it was found that the time series for the rate of change in tangerine prices had a thicker tail rather than a normal distribution. At a significance level of 1%, the Jarque-Bera statistic led to a rejection of the null hypothesis that the distribution of the time series for the rate of change in tangerine prices is normally distributed. Second, the correlation between the time series was high based on the Ljung-Box Q statistic, which was statistically verified through the ARCH-LM test. Third, the results of the GARCH(1,1) model estimation showed statistically significant results at a significance level of 1%, except for the constant of the mean equation. The persistence parameter value of the variance equation was estimated to be close to 1, which means that there is a high possibility that a similar level of volatility will be present in the future. Finally, it is expected that the results of this study can be used as basic data to optimize the government's tangerine supply and demand control policy.

• Journal of Global Scholars of Marketing Science
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• v.17 no.3
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• pp.133-151
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• 2007

The purpose of this article is to examine the effects of item parceling on the consistency of significance testing of the causal parameters with regard to the relationship between the relevant constructs, as well as the effects of the item parceling on the goodness-of-fit indices of LISREL's general models. Most of the researchers' major purpose of using structural equation modeling (SEM) is to test their research hypotheses associated with the causal parameters. Therefore, we investigated three general models of LISREL, rather than the frequently used confirmatory factor analytic (CFA) models by many other researchers. The results of the study showed that there was a high level of consistency in the calculated test statics of causal parameters between the item-parceled solutions and the item-level solutions, and that the item-parceled solutions had better goodness-of-fit indices, such as GFI, AGFI, CFI, and NFI, than the solutions at the item level. However, in terms of RMSEA, there was no such tendency.

• The KIPS Transactions:PartD
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• v.10D no.5
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• pp.829-836
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• 2003

Software Reliability Growth Model that have been studied variously. But measurement of correct parameter of this model is not easy. Specially, estimation of correct model about failure data must be establish and estimation of parameter can consist exactly. To get correct testing, we calculate the normal score and describe the normal probability plot. Use the normal probability plot, we estimate the distribution for failure data. In this paper, we estimate the software reliability growth model for through the normal probability plot. In this research, we applies software reliability growth model through distribution characteristics of failure data. If we see plot, we determine the software reliability growth model, we can make sure superior in model's performance estimation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.2
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• pp.83-94
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• 2010

The objective of this study was to determine the best probability distributions of annual, seasonal and monthly precipitation in Korea. Data observed at 32 stations in Korea were analyzed using the L-moment ratio diagram and the average weighted distance (AWD) to identify the best probability distributions of each precipitation. The probability distribution was best represented by 3-parameter Weibull distribution (W3) for the annual precipitation, 3-parameter lognormal distribution (LN3) for spring and autumn seasons, and generalized extreme value distribution (GEV) for summer and winter seasons. The best probability distribution models for monthly precipitation were LN3 for January, W3 for February and July, 2-parameter Weibull distribution (W2) for March, generalized Pareto distribution (GPA) for April, September, October and November, GEV for May and June, and log-Pearson type III (LP3) for August and December. However, from the goodness-of-fit test for the best probability distributions of the best fit, GPA for April, September, October and November, and LN3 for January showed considerably high reject rates due to computational errors in estimation of the probability distribution parameters and relatively higher AWD values. Meanwhile, analyses using data from 55 stations including additional 23 stations indicated insignificant differences to those using original data. Further studies using more long-term data are needed to identify more optimal probability distributions for each precipitation.

• The Korean Journal of Applied Statistics
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• v.24 no.4
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• pp.567-573
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• 2011

This study develops a predictive model for household water end-uses based on data that have measured household characteristics, housing characteristics and other items, surveyed over 3 years in Korea. However, the measured data was left-skewed and it was not fitted to normal distribution. The parameter estimate were biased when using a multiple regression model. In addition, the results of the testing for the model were usually of significance due to the tiny residual from a large number of observations. In order to solve the problem, we suggested log-normal regression model and Weibull regression model as alternatives. The results of this study can be utilized in the planning stages of water and waste water facilities.

• Journal of the Korea Convergence Society
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• v.10 no.5
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• pp.85-94
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• 2019

This study was aimed to identify a study on the effect of chest compressions combined with abdominal drawing-in technique on prevention of back pain and chest compression quality. We tested motion analysis, electromyography, and chest compression quality of 15 paramedics. Data were normalized to SPSS 21.0 (Kolmogorov-Smirnov and Shapiro-Wilk test). The paired t-test was used for the pre- and post-test chest compressions, the one-way ANOVA was used for the analysis of the measurement point-in-time differences, and LSD was used for the post-test. The results of the study showed significant difference in muscle activity and chest compression success rate when the chest pressure was applied with abdomen drawing-in. Therefore, it is necessary to study cardiopulmonary resuscitation education which can increase the chest compression success rate while preventing the back pain of the paramedics in the future.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.4
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• pp.449-454
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• 1985

In order to search for the semi-dwarf japonica varieties allelic to the semi-dwarf rice cultivar which is controlled by d-t gene, seven dwarf japonica varieties. Reimei, Hoyoku. Shiranui, Kokumasari, M 7. S.224 and S.295 were crossed to the semi-dwarf cultivar, wx 817. wx 817 is known to have semi-dwarf gene d-t. Their F$_1$, F$_2$ and F$_3$ were grown in 1984 and 1985 and culm lengths were measured at harvest. The results are summarized as follows. 1. The F$_2$s of all 7 cross combinations showed normal distribution and no segregation. 2. The range of culm length variation in the F$_3$ was variable depending on the cross combination, but the general pattern was similar in the all 7 crosses. 3. The mean of F$_3$ and parental F$_2$ mean which were selected into short, medium and tall groups were similar and showed no segregation, implying the selection efficiency in F$_2$. 4. From the results of F$_2$ and F$_3$ segregations, it is concluded that the culm length of the 7 semi-dwarf japonicas tested here are controlled by the same major gene d-t although they are modified by different minor genes.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1998.10a
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• pp.107-115
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• 1998

For the purpose of building the simulation model on cargo handling capacity of container terminal, we composed a model of container logistics system which has a 4 subsystems ; cargo handling, transportation, storage system and Gate complex system. Several date used in simulation gained through spot research and basic statistic analysis using raw data from January to Jane in 1998. The results of this study are as follows ; First, average available ratio of each subsystem was G/C 50%, Y/T 57.5%, storage system 56%, Gate complex 50%, and there was no subsystem occurring specific bottleneck. Second, comparing the results of simulation to the results of basic statistics, we can verify suitability of this simulation model. Third, Comparing the results of this study to the results of existed study, we were able to confirm a change of BCTOC container logistics system under IMF situation.