• Communications of the Korean Mathematical Society
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• v.16 no.3
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• pp.399-404
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• 2001

We examine plane waves of the elastic reduced wave equation in the half-space, and show that linear combinations of them can cover all plane waves on the boundary. The proof is based on the complex analysis for the symbol in the (dual) variable in the normal direction to the boundary.

• Communications of the Korean Mathematical Society
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• v.33 no.1
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• pp.127-142
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• 2018

In the present article, authors obtained certain fractional derivative and integral formulas involving incomplete ${\tau}$-hypergeometric function introduced by Parmar and Saxena [14]. Some interesting special cases and consequences of our main results are also considered.

• Bulletin of the Korean Mathematical Society
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• v.57 no.6
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• pp.1427-1449
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• 2020

In this paper, we establish the boundedness of the m-linear Calderón-Zygmund operators on product of central Morrey spaces with variable exponent. The corresponding boundedness properties of their commutators with λ-central BMO symbols are also considered. Finally, we prove that the multilinear commutators of Calderón-Zygmund singular integrals introduced by Pérez and Trujillo-Gonález are bounded on central Morrey spaces with variable exponent. Our results improve and generalize some previous classical results to the variable exponent setting.

• Communications of the Korean Mathematical Society
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• v.37 no.1
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• pp.91-103
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• 2022

In this paper, we introduce Toeplitz operators and Hankel operators with complex Borel measures on the closed unit disk. When a positive measure 𝜇 on (-1, 1) is a Carleson measure, it is known that the corresponding Hankel matrix is bounded and vice versa. We show that for a positive measure 𝜇 on 𝔻, 𝜇 is a Carleson measure if and only if the Toeplitz operator with symbol 𝜇 is a densely defined bounded linear operator. We also study Hankel operators of Hilbert-Schmidt class.

• Journal of the Chungcheong Mathematical Society
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• v.35 no.1
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• pp.1-12
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• 2022

In this paper we prove an even characteristic analogue of the result of Andrade on lower bounds for moment of quadratic Dirichlet L-functions in odd characteristic. We establish lower bounds for the moments of Dirichlet L-functions of characters defined by Hasse symbols in even characteristic.

• Bulletin of the Korean Mathematical Society
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• v.61 no.2
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• pp.529-540
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• 2024

In this paper, using the Fourier transform, inverse Fourier transform and Littlewood-Paley decomposition technique, we prove the boundedness of bilinear pseudodifferential operators with symbols in the bilinear Hörmander class $BS^{m}_{1,1}$ in variable Triebel-Lizorkin spaces and variable Besov spaces.

• Honam Mathematical Journal
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• v.46 no.1
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• pp.60-69
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• 2024

We consider a special orthonormal basis for the Hardy space of the unit disc to compute the matrix representations of the composition operators with respect to the basis particulary associated to two symbols which are the inverse and the origin symmetry of the Riemann self map in the unit disc, and then we find a certain symmetry of the matrices.

• Bulletin of the Korean Mathematical Society
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• v.61 no.4
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• pp.1019-1031
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• 2024

In this paper we consider the sufficient condition for hyponormal Toeplitz operators T_𝛗 with non-harmonic symbols $${\varphi}(z)=\sum_{\ell=1}^{k}{\alpha}_{\ell}z^{{m_{\ell}}{\bar{z}}n_{\ell}}$$ with m_ℓ-n_ℓ = δ > 0 for all 1 ≤ ℓ ≤ k, and α_ℓ ∈ ℂ on the Bergman spaces. In particular, we will observe the characteristics of the hyponormality of the Toeplitz operators T_𝛗 according to the positional relationship of the coefficients α_ℓ's.

• Honam Mathematical Journal
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• v.46 no.3
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• pp.473-484
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• 2024

In recent years, several inequalities have been established when comparing the features of the Berezin transform directly. We examine other inequities associated with them in this work. For the Berezin numbers of a reproducing kernel Hilbert space operator, we therefore derived a variety of upper estimates. A few uses for the outcomes are also provided.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.11 s.353
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• pp.8-15
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• 2006

In this paper, we propose the iterative receiver for LDPC-coded OFDMA systems in uplink environments. Applying the Wiener filtering to pilot symbols, an initial channel estimation can be performed effectively. To reduce the complexity of the Wiener filtering, we approximate Wiener filtering coefficients to pre-determined coefficients according to estimated correlation of channel. After an LDPC decoding process, soft symbol derived by extrinsic information of decoder outputs is used to estimate channel. we also derive the error variance of channel estimation and maximum ratio combined results. Using combined results, the channel correlation is re-estimated. Then the proper Wiener filtering coefficients are chosen according to the re-estimated result of the channel correction. Using a computer simulation, we show that the proposed receiver structure has the better performance than the receiver using only pilot symbols.