• Communications for Statistical Applications and Methods
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• v.8 no.2
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• pp.483-497
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• 2001

When one fits a parametric density function to a data set, it is usually advisable to test the goodness of the postulated model. In this paper we study the nonparametric tests for testing the null hypothesis against general alternatives, when the null hypothesis specifies the density function up to unknown parameters. We modify the test statistic which was proposed by the first author and his colleagues. Asymptotic distribution of the modified statistic is derived and its performance is compared with some other tests through simulation.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1998.10a
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• pp.271-274
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• 1998

In this paper we examine long-term memory of the financial time-series by employing the R/S analysis, the Hurst exponent estimation, and the modified R/S analysis. The null hypothesis of white-noise is tested using the NYSE daily indexes from January 1966 to July 1998, and the results show that long-range dependence exists before the apparent structural break of the Black Monday in 1987.

• Restorative Dentistry and Endodontics
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• v.35 no.1
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• pp.51-58
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• 2010

Dental composites have improved significantly in physical properties over the past few decades. However, polymerization shrinkage and stress is still the major drawback of composites, limiting its use to selected cases. Much effort has been made to make low shrinking composites to overcome this issue and silorane-based composites have recently been introduced into the market. The aim of this study was to measure the volumetric polymerization shrinkage kinetics of a silorane-based composite and compare it with conventional methacrylate-based composites in order to evaluate its effectiveness in reducing polymerization shrinkage. Five commercial methacrylate-based (Beautifil, Z100, Z250, Z350 and Gradia X) and a silorane-based (P90) composites were investigated. The volumetric change of the composites during light polymerization was detected continuously as buoyancy change in distilled water by means of Archemedes' principle, using a newly made volume shrinkage measurement instrument. The null hypothesis was that there were no differences in polymerization shrinkage, peak polymerization shrinkage rate and peak shrinkage time between the silorane-based composite and methacrylate-based composites. The results were as follows: 1. The shrinkage of silorane-based (P90) composites was the lowest (1.48%), and that of Beautifil composite was the highest (2.80%). There were also significant differences between brands among the methacrylate-based composites. 2. Peak polymerization shrinkage rate was the lowest in P90 (0.13%/s) and the highest in Z100 (0.34%/s). 3. The time to reach peak shrinkage rate of the silorane-based composite (P90) was longer (6.7 s) than those of the methacrylate-based composites (2.4-3.1 s). 4. Peak shrinkage rate showed a strong positive correlation with the product of polymerization shrinkage and the inverse of peak shrinkage time (R = 0.95).