• Title/Summary/Keyword: integrals

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FURTHER LOG-SINE AND LOG-COSINE INTEGRALS

  • Choi, Junesang
    • Journal of the Chungcheong Mathematical Society
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    • v.26 no.4
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    • pp.769-780
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    • 2013
  • Motivated essentially by their potential for applications in a wide range of mathematical and physical problems, the log-sine and log-cosine integrals have been evaluated, in the existing literature on the subject, in many different ways. Very recently, Choi [6] presented explicit evaluations of some families of log-sine and log-cosine integrals by making use of the familiar Beta function. In the present sequel to the investigation [6], we evaluate the log-sine and log-cosine integrals involved in more complicated integrands than those in [6], by also using the Beta function.

On set-valued Choquet integrals and convergence theorems(II) (집합치 쇼케이적분과 수렴정리에 관한 연구(II))

  • Jang, Lee-Chae;Kim, Tae-Kyun;Jeon, Jong-Duek
    • Journal of the Korean Institute of Intelligent Systems
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    • v.12 no.4
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    • pp.323-326
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    • 2002
  • In this paper, we consider Choquet integrals of interval number-valued functions(simply, interval number-valued Choquet integrals). Then, we prove convergence theorem for interval number-valued Choquet integrals with respect to an autocontinuous fuzzy measure.

Application of the Expansion Method for Spherical Harmonics for Computation of Overlap Integrals in Molecular System (분자계의 Overlap Integral의 계산의 Spherical Harmonics 전개방법의 응용)

  • Sangwoon Ahn
    • Journal of the Korean Chemical Society
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    • v.22 no.3
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    • pp.117-127
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    • 1978
  • Slater type orbitals, located at two different points A and B, are expressed in a common coordinate system by expanding the spherical harmonics and the radial part of these orbitals in terms of the reference point A. Master formulas for two center overlap integrals are derived, using the general expansion formulas of slater type atomic orbitals. Two center overlap integrals for $CH_4,\;H_2O,\;NH_3,\;C_2H_6\;and\;PH_3$molecules are evaluated, using master formulas for two center overlap integrals. The results are in agreement with those of two center overlap integrals of Mulliken.

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Some characterizations of a mapping defined by interval-valued Choquet integrals

  • Jang, Lee-Chae;Kim, Hyun-Mee
    • International Journal of Fuzzy Logic and Intelligent Systems
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    • v.7 no.1
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    • pp.66-70
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    • 2007
  • Note that Choquet integral is a generalized concept of Lebesgue integral, because two definitions of Choquet integral and Lebesgue integral are equal if a fuzzy measure is a classical measure. In this paper, we consider interval-valued Choquet integrals with respect to fuzzy measures(see [4,5,6,7]). Using these Choquet integrals, we define a mappings on the classes of Choquet integrable functions and give an example of a mapping defined by interval-valued Choquet integrals. And we will investigate some relations between m-convex mappings ${\phi}$ on the class of Choquet integrable functions and m-convex mappings $T_{\phi}$, defined by the class of closed set-valued Choquet integrals with respect to fuzzy measures.

Derivation of Analytic Formulas and Numerical Verification of Weakly Singular Integrals for Near-Field Correction in Surface Integral Equations

  • Rim, Jae-Won;Koh, Il-Suek
    • Journal of electromagnetic engineering and science
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    • v.17 no.2
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    • pp.91-97
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    • 2017
  • An accurate and efficient evaluation for hypersingular integrals (HIs), strongly singular integrals (SSIs), and weakly singular integrals (WSIs) plays an essential role in the numerical solutions of 3D electromagnetic scattering problems. We derive analytic formulas for WSIs based on Stokes' theorem, which can be expressed in elementary functions. Several numerical examples are presented to validate these analytic formulas. Then, to show the feasibility of the proposed formulations for numerical methods, these formulations are used with the existing analytical expressions of HIs and SSIs to correct the near-field interaction in an iterative physical optics (IPO) scheme. Using IPO, the scattering caused by a dihedral reflector is analyzed and compared with the results of the method of moments and measurement data.

A note on compact set-valued Choquet integrals (콤팩트 집합치 쇼케이적분에 관한 연구)

  • Jang Lee-Chae;Kim Hyun-Mee
    • Journal of the Korean Institute of Intelligent Systems
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    • v.15 no.5
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    • pp.588-592
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    • 2005
  • We note that Jang et al. studied closed set-valued Choquet integrals with respect to fuzzy measures. In this paper, we consider Choquet integrals of compact set-valued functions, and prove some properties of them. In particular, using compact set-valued functions instead of interval valued, we investigate characterization of compact set-valued Choquet integrals.

Hyperfine Interaction Integrals for NMR Chemical Shifts in 5f Paramagnetic Systems

  • 이기학;이지영;김동희
    • Bulletin of the Korean Chemical Society
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    • v.18 no.4
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    • pp.424-427
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    • 1997
  • To study the NMR chemical shift arising from the 5f-electron orbital angular momentum and the 5f-electron spin dipolar-nuclear spin angular momentum interactions, the evaluation of the hyperfine integrals has been extended to any pairs of SCF type 5f orbitals adopting a general method which is applicable to a general vector R, pointing in any direction in space. From the electronic wavefunctions for 5f orbitals expressed in common coordinate system, the radial part of the hyperfine interaction integrals are derived by translating the exponential part, r2 exp(-2βr), in terms of R, rN and the modified Bessel functions. The radial integals for 5f orbitals are tabulated in analytical forms. When two of the hyperfine integrals along the (100), (010), (001), (110), and (111) axes are calculated using the derived radial integrals, the calculated values for the 5f system change sign for R-values larger than R 0.35 nm. But the calculated values for the 4f systems change sign for R-values larger than R 0.20 nm.

Calculation of NMR Chemical Shift for a 3d$^1$ System in a Strong Crystal Field Environment of Tetrahedral Symmetry (1). Application of the Expansion Method for a Spherical Harmonics for Derivation of Overlap and the Dipole Moment Matrix Elements of $\mid$4p > Atomic Orbitals and Derivation of the Radial Integrals for the Hyperfine Interaction for $\mid$4p > Atomic Orbitals

  • Ahn, Sang-Woon;Kim, Dong-Hee;Choi, Chang-Jin
    • Bulletin of the Korean Chemical Society
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    • v.7 no.4
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    • pp.299-304
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    • 1986
  • Master formulas for overlap integrals and the dipole moments involving |4p > atomic orbitals have been derived by the expansion method for spherical harmonics. The radial integrals for the hyperfine interaction have also been derived for |4p > atomic orbitals. The calculated values of the overlap integrals and dipole moment matrix elements by the expansion method for spherical harmonics for a hypothetical NO molecule are exactly in agreement with those of Mulliken's method. The radial integrals for the hyperfine interaction may be used to calculate the chemical shift for |4p > atomic orbitals.

FAMILIES OF NONLINEAR TRANSFORMATIONS FOR ACCURATE EVALUATION OF WEAKLY SINGULAR INTEGRALS

  • BEONG IN YUN
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.27 no.3
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    • pp.194-206
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    • 2023
  • We present families of nonlinear transformations useful for numerical evaluation of weakly singular integrals. First, for end-point singular integrals, we define a prototype function with some appropriate features and then suggest a family of transformations. In addition, for interior-point singular integrals, we develop a family of nonlinear transformations based on the aforementioned prototype function. We take some examples to explore the efficiency of the proposed nonlinear transformations in using the Gauss-Legendre quadrature rule. From the numerical results, we can find the superiority of the proposed transformations compared to some existing transformations, especially for the integrals with high singularity strength.