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

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.455-458
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• 1999

It has been known that buildings having inappropriate expansion joints in their spacings may be subject to exterior damages due to extensive cracks on the outer walls under service loads, and structural damages due to excessive moment induced by temperature changes at ultimate load conditions. Rather inconsistent code provisions are available regarding spacings of expansion joints from different foreign structural codes and even worse, no quantiative measure on spacings is given in our codes for building structures. In order to establish a rational measure on the spacing of expansion joints, theoretical approaches are taken in this study. The developed theoretical formula is, then, converted to design chart for structural designer's convenience in its use. The chart considers both service and ultimate load stages.

• Journal of Ocean Engineering and Technology
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• v.6 no.1
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• pp.52-61
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• 1992

The steady laminar mixed convection from vertically misaligned, isothermal plastes has been studied by numerical procedure. The governing equations are solved by the finite difference method using successive using successive over relaxation scheme at Re=100-800, $Gr=10^3-10^6$, Pr=0.71 and dimensionless plate spacings b/L=0.1-1.0. The plume interaction caused by the thermal interference of twoplates is observed. As Reynolds numbers increase, the optimum plate spacings are moved to narrow spacings at the same Grashof number and as Grashof numbers increase, to wide spacings at the same Reynolds number.

• Journal of the Korean Statistical Society
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• v.26 no.3
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• pp.289-297
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• 1997

It is well known that the spacings, the differences of two successive order statistics, in a random sample of size n from a distribution function F are independent and exponentially distributed if F is itself the exponential distribution. In this paper we obtain an asymptotically similar result on a fixed number of upper spacings as n .to. .infty. for a general F under the assumption that F is in the domain of attraction of some extreme value distribution. For a heavy or short tailed F, appropriate log transformations of the sample should be proceded to get the result. As a by-product, we also get that each upper spacing diverges in probability to .infty. and converges in probability to 0 as n .to. .infty. for a heavy and short tailed F, respectively, which is fully expected.

• KCI Concrete Journal
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• v.12 no.1
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• pp.101-111
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• 2000

It has been a well known fact that buildings having inappropriate expansion joints in their spacings may be subject to exterior damages due to extensive cracks on the outer walls under service loads and structural damages due to excessive moment induced by temperature changes at ultimate load conditions. Unfortunately, consistent code provisions are unavailable regarding spacings of expansion joints from different foreign structural codes. And a more serious problem is that no quantitative measurements on spacings is given in our codes for building structures. In order to establish a rational guideline on the spacing of expansion joints, theoretical approaches are taken in this study. The developed theoretical formula is, then, converted to a design chart for structural designers' convenience in its use. The chart considers both service and ultimate load stages.

• Communications for Statistical Applications and Methods
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• v.7 no.3
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• pp.955-958
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• 2000

In this paper, it will be shown that if the distribution function F of X is increasing (decresign) failure rate, then the spacings are engatively( Positively) dependent. Some numberical exmamples are illustrated.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.12 no.1
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• pp.51-70
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• 2001

Characteristics of handwriting were investigated and compared between the patients with writing disabilities and normal elementary school pupils. Generally, the heights of the letters of the patients were significantly larger than those of normal children, and letters of the patients were more sparsely distributed than those of controls. The distance between the words were significantly reduced in the patients’ writings, which indicated that patients had much more problems of space-leaving than normal pupils. Letter heights differences were significant across all grades in the patients and normal controls. The heights of the letters decreased as they grew older, and the slope of the decrements were more steeper in normal girls(r=-0.45) than girls with writing disabilities(r=-0.16). Sex differences were found in the letter spacings in low grades(grades 1, 2), that is, the distances between the letters were significantly narrower in the male patients than normal boys in these grades, and the differences were almost indiscriminating in grades 3 through 5, and finally, in sixth grade, letter spacings were signifycantly broader in normal boys than male dysgraphics. In girls, letter spacings were significantly broader in the patients across all grades. These findings supports the hypothesis that male and female writings were qualitatively different and that distinct mechanisms served in boys and girls dysgraphics. Across all grades and sexes, spaces between the words of the patients were significantly broader than normal pupils, which suggested that space-leaving between the words was important in Korean writings. There was trend that letter spacings and word spacings decreased across grades, but in girls, no correlations between the letter spacings and grades were found. Correlation analyses revealed that letter heights and letter spacings had mild correlation(r=0.11-0.15), and that letter spacings and word spacings had robust correlation(r=0.99). Phonological errors were mostly found in last phoneme(Jong-seong), especially double-phoneme(ㄳ, ㄵ, ㄶ, ㄺ, ㄻ, ㄼ, ㄾ, ㄿ, ㅀ, ㅄ), and in the case the sound values changed due to assimilations of phonemes. Semantic errors were rare in both groups. Space-leaving errors were correlated with phonological errors, and more frequent in boys than girls. In conclusion, significant differences existed in the letter heights, letter spacings, word spacings, and frequencies of phonological errors and spaceleaving errors between the patients with writing disabilities and normal pupils. The characteristics of writings changed across grades and the developmental profiles were somewhat quantitatively different between the groups. The differences became obvious from the second-third grades.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.10
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• pp.1285-1295
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• 1999

An experimental study on heat transfer and flow characteristics of a circular impinging jet on a flat plate has been carried out. Of particular interests are the effects of nozzle wall thickness and nozzle exit pressure. Experimental apparatus has been designed to view heating plate coated by TLC from the opposite side of the nozzle in order to measure heat transfer rates for cases of very small nozzle to plate spacings. A visualization study of jet flows has also been performed. As the nozzle wall thickness increases at small nozzle to plate spacings, the effect of mixing is inhibited due to the confinement caused by the finite nozzle wall, consequently, heat transfer rates have been decreased. At small nozzle to plate spacings, heat transfer rates and nozzle exit pressures are increased together, therefore, enhancement of heat transfer at small nozzle to plate spacings should be considered in conjunction with the need of more fan power to generate the same Reynolds numbers.

• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1645-1651
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• 1990

The steady laminar mixed convection from two finite vertical parallel plates has been studied by numerical procedure. The governing equations are solved by the finite difference method and point successive over relaxation scheme at R3=100-1000, Gr=0-10$^{6}$ , Pr=0.71 and dimensionless plate spacing b/$\ell$=0.05-0.1. The plume interaction caused by the thermal interference of two plates is observed. As Reynolds numbers are increased, optimum plate spacings are moved to narrow spacings at the same Grashof number, and as Grashof numbers are increased, to wide spacings at the same Reynolds number.

• Communications for Statistical Applications and Methods
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• v.29 no.6
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• pp.665-677
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• 2022

This paper proposes a new estimation method based on the maximum product of spacings for estimating unknown parameters of the three-parameter Weibull distribution under a generalized Type-II progressive hybrid censoring scheme which guarantees a constant number of observations and an appropriate experiment duration. The proposed approach is appropriate for a situation where the maximum likelihood estimation is invalid, especially, when the shape parameter is less than unity. Furthermore, it presents the enhanced performance in terms of the bias through the Monte Carlo simulation. In particular, the superiority of this approach is revealed even under the condition where the maximum likelihood estimation satisfies the classical asymptotic properties. Finally, to illustrate the practical application of the proposed approach, the real data analysis is conducted, and the superiority of the proposed method is demonstrated through a simple goodness-of-fit test.