• Journal of Mechanical Science and Technology
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• 제14권1호
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• pp.39-47
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• 2000

Bifurcation intability modes of axially compressed circular cylindrical shell are investigated in the limit of zero thickness (i.e., h (thickness) ${\rightarrow}$ 0) analytically, adopting the general stability theory developed by Triantafyllidis and Kwon (1987) and Kwon (1992). The primary state of the shell is obtained in a closed form using the asymptotic technique, and then the straight-forward bifurcation analysis is followed according to the general stability theory to obtain the bifurcation modes in the limit of zero thickness in a full analytical manner. Hence, the closed form bifurcation solution is obtained. Finally, the result is compared with the classical one.

• 품질경영학회지
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• 제21권2호
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• pp.162-169
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• 1993

For the problem of testing the parallelism of several regression lines against ordered alternatives, two test statistics and proposed and examined. The proposed statistics are linear combinations of robust estimators of slope parameters, which are modifications of the Adichie (1976) test based on scores. The asymptotic null variances of the proposed states tics are estimated by the kernel density estimation methods. The proposed tests are compared with the Adichie's test in terms of asymptotic relative efficiency and small-sample powers.

• Journal of Communications and Networks
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• 제18권1호
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• pp.19-26
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• 2016

In this paper, the performance of dual-hop multi-relay maximum ratio transmission (MRT) over Rayleigh flat fading channels is studied with both conventional (all relays participate the transmission) and opportunistic (best relay is selected to maximize the received signal-to-noise ratio (SNR)) relaying. Performance analysis starts with the derivation of the probability density function, cumulative distribution function and moment generating function of the SNR. Then, both approximate and asymptotic expressions of symbol error rate (SER) and outage probability are derived for arbitrary numbers of antennas and relays. With the help of asymptotic SER and outage probability, diversity and array gains are obtained. In addition, impact of imperfect channel estimations is investigated and optimum power allocation factors for source and relay are calculated. Our analytical findings are validated by numerical examples which indicate that multi-relay MRT can be a low complexity and reliable option in cooperative networks.

• Journal of applied mathematics & informatics
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• 제41권6호
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• pp.1341-1364
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• 2023

This article introduces a method for estimating the conditional hazard function of a real-valued response variable based on a functional variable. The method uses local linear estimation of the conditional density and cumulative distribution function and is applied to a functional stationary ergodic process where the explanatory variable is in a semi-metric space and the response is a scalar value. We also examine the uniform almost complete convergence of this estimation technique.

• Communications for Statistical Applications and Methods
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• 제21권2호
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• pp.115-124
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• 2014

In this paper we derive a Berry-Esseen type bound for the kernel density estimator of a random left truncated model, in which each datum (Y) is randomly left truncated and is sampled if $Y{\geq}T$, where T is the truncation random variable with an unknown distribution. This unknown distribution is estimated with the Lynden-Bell estimator. In particular the normal approximation rate, by choice of the bandwidth, is shown to be close to $n^{-1/6}$ modulo logarithmic term. We have also investigated this normal approximation rate via a simulation study.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제23권3호
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• pp.205-221
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• 2016

We formulate the additive entropy of a natural number in terms of the additive partition function, and show that its multiplicative entropy is directly related to the multiplicative partition function. We give a practical formula for the multiplicative entropy of natural numbers with two prime factors. We use this formula to analyze the comparative density of additive and multiplicative entropy, prove that this density converges to zero as the number tends to infinity, and empirically observe this asymptotic behavior.

• 한국통신학회논문지
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• 제31권1C호
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• pp.20-25
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• 2006

본 논문에서는 Tree-LDPC 코드의 성능을 scaling 인자를 이용한 min-sum 알고리즘을 사용하여 나타내고, 그때의 water fall 영역에서의 접근 성능은 density evolution 기법을 사용하여 나타낸다. Density evolution 기법을 통하여 얻어진 최적의 scaling 인자를 사용하게 되면 min-sum 알고리즘을 사용하는 Tree-LDPC 코드는 sum-product 알고리즘을 사용했을 때와 비슷한 성능을 나타낼 정도로 상당한 성능 이득을 갖게 되는 반면 sum-product 알고리즘을 사용했을 때보다 복호 복잡도가 훨씬 줄어들게 된다. 작은 인터리버 크기를 갖는 Tree-LDPC 복호기를 FPGA(Field Programmable Gate Array)로 구현하였다.

• 천문학회지
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• 제38권2호
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• pp.267-270
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• 2005

We investigate the spectral energy distributions (SEDs) of low mass-loss rate O-rich asymptotic giant branch (AGB) stars using the infrared observational data including the Infrared Space Observatory (ISO) data. Comparing the results of detailed radiative transfer model calculations with observations, we find that the dust formation temperature is much lower than 1000 K for standard dust shell models. We find that the superwind model with a density-enhanced region can be a possible alternative dust shell model for LMOA stars.

• Journal of applied mathematics & informatics
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• 제26권1_2호
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• pp.177-189
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• 2008

In this paper, we have considered an investigation on goodness of fit tests based on divergence measures. In the case of categorical data, under certain regularity conditions, we obtained asymptotic distribution of these tests. Also, we have proposed a modified test that improves the rate of convergence. In continuous case, we used our modified entropy estimator [10], for Kullback-Leibler information estimation. A comparative study based on simulation results is discussed also.

• Journal of the Korean Statistical Society
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• 제23권1호
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• pp.89-102
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• 1994

A new method for approximating the average run length (ARL) of cumulative sum (CUSUM) chart is proposed. This method uses the conditional expectation for the test statistic before the stopping time and its asymptotic conditional density function. The values obtained by this method are compared with some other methods in normal and exponential case.