• Honam Mathematical Journal
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• v.42 no.4
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• pp.781-794
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• 2020

In this article, we investigate the upper bounds on the coefficients for inverse of functions belongs to certain classes of univalent functions and in particular for the functions convex in one direction. Bounds on the Fekete-Szegö functional and third order Hankel determinant for these classes have also investigated.

• Korean Journal of Mathematics
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• v.10 no.1
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• pp.67-74
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• 2002

Suppose linear forms whose coefficients are arithmetic progressions are given. In this paper, we will find the upper and lower bounds of the minimal ranks of subforms of these forms which left the Frobenius numbers invariant. This is an improvement of Ritter's bounds.

• Kyungpook Mathematical Journal
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• v.61 no.3
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• pp.583-590
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• 2021

In this work we give new upper and lower bounds for the numerical radius of a complex square matrix A using the entries and the trace of A.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.2A
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• pp.138-143
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• 2006

We present upper bounds for the maximum-likelihood decoding performance of particular LDPC codes and turbo-like codes with particular interleavers. Previous research developed upper bounds for LDPC codes and turbo-like codes using ensemble codes or the uniformly interleaved assumption, which bound the performance averaged over all ensemble codes or all interleavers. Proposed upper bounds are based on the simple bound and estimated weight distributions including the exact several smallest distance terms because if either estimated weight distributions on their own or the exact several smallest distance terms only are used, an accurate bound can not be obtained.

• Structural Engineering and Mechanics
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• v.21 no.2
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• pp.185-204
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• 2005

Variations in system parameters due to uncertainties may result in system performance deterioration. Uncertainties in modeling of structures are often considered to ensure that control system is robust with respect to response errors. Hence, the uncertain concept plays an important role in vibration control of the engineering structures. The paper discusses the robustness of the stability of vibration control systems with uncertain parameters. The vibration control problem of an uncertain system is approximated by a deterministic one. The uncertain parameters are described by interval variables. The uncertain state matrix is constructed directly using system physical parameters and avoided to use bounds in Euclidean norm. The feedback gain matrix is determined based on the deterministic systems, and then it is applied to the actual uncertain systems. A method to calculate the upper and lower bounds of eigenvalues of the close-loop system with uncertain parameters is presented. The lower bounds of eigenvalues can be used to estimate the robustness of the stability the controlled system with uncertain parameters. Two numerical examples are given to illustrate the applications of the present approach.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1080-1089
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• 1999

The union upper bounds to the bit error probability of maximum likelihood(ML) soft-decoding of parallel concatenated convolutional codes(PCCC) and serially concatenated convolutional codes(SCCC) can be evaluated through the weight enumerating function(WEF). This union upper bounds become the lower bounds of the BER achievable when iterative decoding is used. In this paper, to compute the WEF, an efficient error event search algorithm which is a combination of stack algorithm and bidirectional search algorithm is proposed. By computor simulation, it is shown that the union boounds obtained by using the proposed algorithm become the lower bounds to BER of concatenated convolutional codes with iterative decoding.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.144-147
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• 1987

An adaptive control algorithm for a plant with unmodelled dynamics is proposed. The upper bounds of the output due to the unmodelled dynamics and measurement noise is assumed to be known. Linear programming is used in estimating the bounds of plant parameters. Projection type algorithm is used in estimating the plant parameter with these bounds. This algorithm is nearly the same as those proposed by Kreisselmeier or Middleton except that the bounds are computed by linear programming. The stability of the proposed algorithm Can be proved in nearly the same way as that of Middleton. Simulation results show that the proposed algorithm gives better parameter convergence and smaller overshoot in the plant output than the algorithm without computing the bounds of plant parameters by linear programming.

• Bulletin of the Korean Mathematical Society
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• v.38 no.4
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• pp.797-801
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• 2001

The purpose of this paper is to give an upper bound for A[n,4], the maximum number of codewords in a binary code of word length n with minimum distance 4 between codewords. We have improved upper bound for A[12k+11,4]. In this correspondence we prove $A[23,4]\leq173716$.

• Korean Journal of Mathematics
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• v.5 no.2
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• pp.127-134
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• 1997

On the setting of the upper half-space of the euclidean n-space, we study some properties of harmonic little Bloch functions and we show that for a given harmonic little Bloch function $u$, there exists unique harmonic conjugates of $u$, which are also little Bloch functions with appropriate norm bounds.

• East Asian mathematical journal
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• v.28 no.5
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• pp.579-585
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• 2012

Let D be a finite digraph with the vertex set V(D) and arc set A(D). A two-valued function $f:V(D){\rightarrow}\{-1,\;1\}$ defined on the vertices of a digraph D is called a signed 2-independence function if $f(N^-[v]){\leq}1$ for every $v$ in D. The weight of a signed 2-independence function is $f(V(D))=\sum\limits_{v{\in}V(D)}\;f(v)$. The maximum weight of a signed 2-independence function of D is the signed 2-independence number ${\alpha}_s{^2}(D)$ of D. Recently, Volkmann [3] began to investigate this parameter in digraphs and presented some upper bounds on ${\alpha}_{s}^{2}(D)$ for general digraph D. In this paper, we improve upper bounds on ${\alpha}_s{^2}(D)$ given by Volkmann [3].