• Nuclear Engineering and Technology
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• v.54 no.4
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• pp.1185-1194
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• 2022

The maintenance of condenser main pipe is the key to achieve film-forming amine maintenance effectiveness. In this work, oxygen content, pH and temperature of the solution were controlled to simulate the condition of condenser main pipe, and magnetite coated carbon steel sample was prepared by pre-oxidization. CAM was used to characterize the hydrophobicity of film formed samples. Hydrophobic film was formed on pre-oxidized carbon steel samples when octadecylamine concentration reaches 20 mg/kg. SEM, EDS, EIS, and PD were used to characterize the influence of octadecylamine concentration on maintenance effectiveness. It was found that the maintenance effectiveness was enhanced and the corrosion rate was suppressed with the increase of octadecylamine concentration. FIB and TEM were used to detect the adsorbed octadecylamine film thickness founding that octadecylamine adsorbed onto the surface of pre-oxidized carbon steel by multi-layer adsorption mechanism.

• Journal of the Korean Mathematical Society
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• v.60 no.5
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• pp.959-986
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• 2023

Zhai and Lin recently proved that if G is an n-vertex connected 𝜃(1, 2, r + 1)-free graph, then for odd r and n ⩾ 10r, or for even r and n ⩾ 7r, one has ${\rho}(G){\leq}{\sqrt{{\lfloor}{\frac{n^2}{4}}{\rfloor}}}$, and equality holds if and only if G is $K_{{\lceil}{\frac{n}{2}}{\rceil},{\lfloor}{\frac{n}{2}}{\rfloor}}$. In this paper, for large enough n, we prove a sharp upper bound for the spectral radius in an n-vertex H-free non-bipartite graph, where H is 𝜃(1, 2, 3) or 𝜃(1, 2, 4), and we characterize all the extremal graphs. Furthermore, for n ⩾ 137, we determine the maximum number of edges in an n-vertex 𝜃(1, 2, 4)-free non-bipartite graph and characterize the unique extremal graph.

• Communications of the Korean Mathematical Society
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• v.38 no.2
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• pp.451-459
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• 2023

We give a characterization of zero divisors of the ring C[a, b]. Using the Weierstrass approximation theorem, we completely characterize topological divisors of zero of the Banach algebra C[a, b]. We also characterize the zero divisors and topological divisors of zero in ℓ^∞. Further, we show that zero is the only zero divisor in the disk algebra 𝒜 (𝔻) and that the class of singular elements in 𝒜 (𝔻) properly contains the class of topological divisors of zero. Lastly, we construct a class of topological divisors of zero of 𝒜 (𝔻) which are not zero divisors.

• Bulletin of the Korean Mathematical Society
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• v.60 no.2
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• pp.475-484
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• 2023

Let R be a commutative ring with identity. In this paper, we characterize the prime submodules of a free R-module F of finite rank with at most n generators, when R is a GCD domain. Also, we show that if R is a Bézout domain, then every prime submodule with n generators is the row space of a prime matrix. Finally, we study the existence of primary decomposition of a submodule of F over a Bézout domain and characterize the minimal primary decomposition of this submodule.

• The Pure and Applied Mathematics
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• v.31 no.1
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• pp.1-19
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• 2024

In this paper, the notions of strong Connes amenability for certain products of Banach algebras and module extension of dual Banach algebras is investigated. We characterize χ ⊗ η-strong Connes amenability of projective tensor product ${\mathbb{K}}{\hat{\bigotimes}}{\mathbb{H}}$ via χ ⊗ η-σwc virtual diagonals, where χ ∈ 𝕂_* and η ∈ ℍ_* are linear functionals on dual Banach algebras 𝕂 and ℍ, respectively. Also, we present some conditions for the existence of (χ, θ)-σwc virtual diagonals in the θ-Lau product of 𝕂 ×_θ ℍ. Finally, we characterize the notion of (χ, 0)-strong Connes amenability for module extension of dual Banach algebras 𝕂 ⊕ 𝕏, where 𝕏 is a normal Banach 𝕂-bimodule.

• Kyungpook Mathematical Journal
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• v.43 no.4
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• pp.547-566
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• 2003

In this paper, we introduce the notion of Maass-Jacobi forms and investigate some properties of these new automorphic forms. We also characterize these automorphic forms in several ways.

• Journal of the Chungcheong Mathematical Society
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• v.10 no.1
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• pp.1-7
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• 1997

We characterize fuzzy ideals in near-rings and extensions of such ideals with the sup property.

• Journal of the Chungcheong Mathematical Society
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• v.27 no.1
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• pp.99-103
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• 2014

In this paper, we characterize the m-isometric weighted shifts, using this characterization, we study the relations between the hyponormality and the m-isometricity of operators.

• Journal of the Chungcheong Mathematical Society
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• v.29 no.4
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• pp.553-563
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• 2016

We characterize periodicities of some characteristic matrices of cellular automata congured with rule 60 and intermediate boundary condition.

• The Pure and Applied Mathematics
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• v.9 no.1
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• pp.73-79
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• 2002

In this paper, We Characterize the Pettis integrability for the Dunford integrable functions on a perfect finite measure space.