• 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.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2271-2282
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• 1995

Numerical simulations for the effects of secondary flow and turbulence diffusion on the particle concentration distributions have been carried out for the single stage electrostatic precipitator. The electrohydrodynamic secondary flow, particle concentration distribution and collection efficiency have been evaluated as a function of dimensionless parameters such as Re, $N_{end}$, $P_{e}$ x. The results of simulations show that for increasing secondary flow intensity the concentration distribution is drastically deformed and collection efficiency is decreased which is more than due to turbulent diffusion.n.n.

• Communications of the Korean Mathematical Society
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• v.34 no.4
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• pp.1289-1301
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• 2019

In the present paper, we prove that if there exists a second order parallel tensor on an almost Kenmotsu manifold with generalized $(k,{\mu})^{\prime}$-nullity distribution and $h^{\prime}{\neq}0$, then either the manifold is isometric to $H^{n+1}(-4){\times}{\mathbb{R}}^n$, or, the second order parallel tensor is a constant multiple of the associated metric tensor of $M^{2n+1}$ under certain restriction on k, ${\mu}$. Besides this, we study Ricci soliton on an almost Kenmotsu manifold with generalized $(k,{\mu})^{\prime}$-nullity distribution. Finally, we characterize such a manifold admitting generalized Ricci soliton.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.8
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• pp.611-617
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• 2001

The non-polar optical phonon scattering in the valence band depends on the masses, ratios, and types of mixtures of constituent atoms. Therefore, the random distribution of atoms in alloy semiconductors should be considered in the analysis of scattering mechanisms. For this purpose, the force equations of n atoms in a unit cell are expressed in a n x n matrix form to obtain the angular frequencies due to the acoustic and non-polar optical phonons. And, n is then assumed to be infinity. When this work is compared with other results published elsewhere, it is concluded that the independence of atomic displacement or amplitude of oscillation as ell as the infinite number of atoms in a unit cell must be taken into account for the random distribution of atoms in alloy semiconductors.

• Current Optics and Photonics
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• v.2 no.5
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• pp.468-473
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• 2018

We investigate the temperature dependence of efficiency droop in InGaN/GaN multiple-quantum-well (MQW) blue light-emitting diodes (LEDs) in the temperature range from 20 to $80^{\circ}C$. When the external quantum efficiency (EQE) and the wall-plug efficiency (WPE) of the LED sample were measured as injection current and temperature varied, the droop of EQE and WPE was found to be reduced with increasing temperature. As the temperature increased from 20 to $80^{\circ}C$, the droop ratio of EQE was decreased from 16% to 14%. This reduction in efficiency droop with temperature can be interpreted by a temperature-dependent carrier distribution in the MQWs. When the carrier distribution and radiative recombination rate in MQWs were simulated and compared for different temperatures, the carrier distribution was found to become increasingly homogeneous as the temperature increased, which is believed to partly contribute to the reduction in efficiency droop with increasing temperature.

• Journal of the Chungcheong Mathematical Society
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• v.26 no.2
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• pp.269-273
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• 2013

We prove a characterization of the power function distribution by lower record values. We prove that $F(x)=(\frac{x}{a})^{\alpha}$ for all $x$, 0 < $x$ < $a$, ${\alpha}$ > 0 and $a$ > 0 if and only if $\frac{X_{L(n)}}{X_{L(m)}}$ and $X_{L(m)}$ are independent for $1{\leq}m$ < $n$.

• Journal of the Chungcheong Mathematical Society
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• v.27 no.2
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• pp.243-247
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• 2014

Let {$X_n$, $n{\geq}1$} be a sequence of i.i.d. random variables with absolutely continuous cumulative distribution function(cdf) F(x) and the corresponding probability density function(pdf) f(x). In this paper, we give characterizations of Pareto and Weibull distribution by considering conditional expectations of record values.

• Journal of applied mathematics & informatics
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• v.35 no.5_6
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• pp.651-657
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• 2017

A sequence {$X_n,\;n{\geq}1$} of independent and identically distributed random variables with absolutely continuous (with respect to Lebesque measure) cumulative distribution function F(x) is considered. We obtain two characterizations of a family of continuous probability distribution by independence property of record values.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1700-1702
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• 2001

This paper describes that PD sources in GIS were recognized using fuzzy algorithm proposed in this paper. PD sources were classified by four states and PD signals were expressed by $\phi$-q distribution. $\phi$-N distribution and Q-N distribution. Then statistical operators were extracted from each distributions. As a result, the rate of recognizing PD sources in GIS using fuzzy algorithm proposed in this paper was 93[%].

• Journal of the Chungcheong Mathematical Society
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• v.30 no.3
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• pp.285-289
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• 2017

Let $\{X_n,\;n{\geq}1\}$ be a sequence of independent and identically distributed random variables with cdf F(x) which is absolutely continuous with pdf f(x) and F(x) < 1 for all x in ($-{\infty},\;{\infty}$). In this paper, we obtain the characterizations of the Gumbel distribution by lower record values.