• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.10
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• pp.1100-1108
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• 1992

The evaluation of coded error probabilities for antijam communication systems is usually difficult to do and, thus, easy-to-evaluate upper bounds are used. Since it is relatively easy to evaluate the cutoff rate for the coding channel, the coded bit error bounds for most antijam systems of interest can be easily expressed directly in terms of this cutoff rate parameter using the relationship between the bit error bounds and cutoff rate for AWGN channel. The key feature of these bounds is the decoupling of the coding aspects of the system from the remaining part of the communication system which includes jamming, suboptimum detectors, and arbitrary decoding metrics which may or may not use jammer state knowledge. In this paper the bit error bounds for the Trumpis coded FH/MFSK with an AWGN channel are translated into the corresponding bit error bounds for boradband and partial band noise jammer. And the impact of the side information about jammer state is also evaluated with these upper bounds. Although it is considered for the soft decision detector, it is also applicable to the hard decision detector.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.9
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• pp.34-43
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• 1994

The unequal symbol error probability of TCM(trellis coded modulation) is analyzed and applied to the derivation of bit error probability of /RS/Trellis concatenated coded-modulation system. An upper bound of the symbol error probability of TCM concatenated with RS code is obtained by exploiting the unequal symbol error probability of TCM, and it is applied to the derivation of the upper bound of the bit error probability of the RS/Trellis concatenated coded-modulation system. Our upper bounds of the concatenated codes are tighter than the earlier established other upper bounds.

• Management Science and Financial Engineering
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• v.8 no.1
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• pp.1-19
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• 2002

Ordering is used to reduce the amount of fill-ins in the Cholesky factor of a symmetric positive definite matrix. One of the most efficient ordering methods is the minimum degree ordering algorithm(MDO). In this paper, we provide a few techniques that improve the performance of MDO implemented with the clique storage scheme. First, the absorption of nodes in the cliques is developed which reduces the number of cliques and the amount of storage space required for MDO. Second, we present a modified minimum degree ordering algorithm of which the number of degree updates can be reduced by introducing the lower bounds of degrees. Third, using both the lower and upper bounds of degrees, we develop an approximate minimum degree ordering algorithm. Experimental results show that the proposed algorithm is competitive with the minimum degree ordering algorithm that uses quotient graphs from the points of the ordering time and the nonzeros in the Cholesky factor.

• Kyungpook Mathematical Journal
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• v.55 no.1
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• pp.169-180
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• 2015

We study the braid indices of the Kanenobu knots. It is known that the Kanenobu knots have the same HOMFLYPT polynomial and the same Khovanov-Rozansky homology. The MFW inequality is known for giving a lower bound of the braid index of a link by applying the HOMFLYPT polynomial. Therefore, it is not easy to determine the braid indices of the Kanenobu knots. In our previous paper, we gave upper bounds and sharper lower bounds of the braid indices of the Kanenobu knots by applying the 2-cable version of the zeroth coefficient HOMFLYPT polynomial. In this paper, we give sharper upper bounds of the braid indices of the Kanenobu knots.

• Communications for Statistical Applications and Methods
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• v.24 no.6
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• pp.641-649
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• 2017

Multivariate confidence regions were defined using a chi-square distribution function under a normal assumption and were represented with ellipse and ellipsoid types of bivariate and trivariate normal distribution functions. In this work, an alternative confidence region using the multivariate quantile vectors is proposed to define the normal distribution as well as any other distributions. These lower and upper bounds could be obtained using quantile vectors, and then the appropriate region between two bounds is referred to as the quantile confidence region. It notes that the upper and lower bounds of the bivariate and trivariate quantile confidence regions are represented as a curve and surface shapes, respectively. The quantile confidence region is obtained for various types of distribution functions that are both symmetric and asymmetric distribution functions. Then, its coverage rate is also calculated and compared. Therefore, we conclude that the quantile confidence region will be useful for the analysis of multivariate data, since it is found to have better coverage rates, even for asymmetric distributions.

• Journal of Korean Society for Quality Management
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• v.21 no.2
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• pp.93-101
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• 1993

The derived expressions and computations of the system reliability in the consecutive k out of n failure structure with sink-source pole are discussed and a decisive lower and upper bounds as well as exact system reliability are presented in this paper. Good bounds of the system reliability can be easily computed and are illustrated in the numerical example.

• International Journal of Reliability and Applications
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• v.17 no.1
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• pp.51-63
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• 2016

Stress function of ball bearing is function of multiple stochastic factors and this system is so complex that analytical expression for reliability is difficult to obtain. To address this pressing problem, in this article, we have made an attempt to approximate system reliability of this important item based on reliability bounds under the stress strength setup. This article also provides level of error of this item. Numerical analysis has been adopted to show the closeness between the upper and lower bounds of this item.

• Journal of the Korean Statistical Society
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• v.32 no.4
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• pp.359-371
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• 2003

We consider the probability that the total population of a stable Jackson network reaches a given large value. By using the fluid limit of the reversed network, we derive new upper and lower bounds on this probability, which are sharper than those in Glasserman and Kou (1995). In particular, the improved lower bound is useful for analyzing the performance of an importance sampling estimator for the overflow probability in Jackson tandem networks. Bounds on the expected time to overflow are also obtained.

• Journal of applied mathematics & informatics
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• v.9 no.1
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• pp.321-330
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• 2002

We apply an Intermediate Problem Method to compute eigenvalues of an anharmonic oscillator. The method produces lower bounds to the eigenvalues while the Rayleigh-Ritz method yields upper bounds. We show the convergence rate of the Intermediate Problem Method is the same as the rate of the Rayleigh-Ritz method.

• Kyungpook Mathematical Journal
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• v.59 no.3
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• pp.493-503
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• 2019

In the present investigation, we define two new subclasses of analytic and m-fold symmetric bi-univalent functions defined by a linear combination in the open unit disk U. Furthermore, for functions in each of the subclasses introduced here, we establish upper bounds for the initial coefficients ${\mid}a_{m+1}{\mid}$ and ${\mid}a_{2m+1}{\mid}$. Also, we indicate certain special cases for our results.