Oh Sang Kwon

Inclusion relationships for certain subclasses of meromorphic functions associated with a family of multiplier transformations

The purpose of the present article is to introduce several new subclasses of meromorphic functions defined by using the multiplier transformation and investigate various inclusion relationships for these subclasses. Some interesting applications involving a certain class of integral operators are also considered.

A class of integral operators preserving subordination and superordination for meromorphic functions

The purpose of the present paper is to investigate several subordination- and superordination-preserving properties of a certain class of integral operators, which are defined on the space of meromorphic functions in the punctured open unit disk. The sandwich-type theorem for these integral operators is also presented. Moreover, we consider an application of the subordination and superordination theorem to the Gauss hypergeometric function.

Strong differential subordination and superordination for multivalently meromorphic functions involving the Liu–Srivastava operator

Strong differential subordination and superordination properties are determined on the Liu–Srivastava operator (which, just as the relatively more familiar Dziok–Srivastava operator, is defined by using a generalized hypergeometric function) for some families of multivalently meromorphic functions in the punctured open unit disk by investigating appropriate classes of admissible functions. New strong differential sandwich-type results for the Liu–Srivastava operator are also obtained.

Inclusion Properties for Certain Subclasses of Analytic Functions Associated with the Dziok-Srivastava Operator

The purpose of the present paper is to introduce several new classes of analytic functions defined by using the Choi-Saigo-Srivastava operator associated with the Dziok-Srivastava operator and to investigate various inclusion properties of these classes. Some interesting applications involving classes of integral operators are also considered.

Coefficient, distortion and growth inequalities for certain close-to-convex functions

In the present investigation, certain subclasses of close-to-convex functions are investigated. In particular, we obtain an estimate for the Fekete-Szegö functional for functions belonging to the class, distortion, growth estimates and covering theorems.Mathematics Subject Classification (2010): 30C45, 30C80.

Notes on analytic functions with a bounded positive real part

For real α and β such that 0≤α<1<β, we denote by S(α,β) the class of normalized analytic functions f such that α<Re{zf′(z)/f(z)}<β in . We find some properties, including inclusion properties, Fekete-Szegö problem and coefficient problems of inverse functions.MSC:30C45, 30C55.

A Subclass of Meromorphic Close-to-Convex Functions of Janowski's Type

We introduce a subclass Σ(𝐴,𝐵)(−1≤𝐵<𝐴≤1) of functions which are analytic in the punctured unit disk and meromorphically close-to-convex. We obtain some coefficients bounds and some argument and convolution properties belonging to this class.

Subordination and Superordination for Multivalent Functions Associated with the Dziok-Srivastava Operator

Subordination and superordination preserving properties for multivalent functions in the open unit disk associated with the Dziok-Srivastava operator are derived. Sandwich-type theorems for these multivalent functions are also obtained.

A Class of Nonlinear Integral Operators Preserving Double Subordinations

The purpose of the present paper is to investigate some subordination- and superordination-preserving properties of certain integral operators defined on the space of meromorphic functions in the punctured open unit disk. The sandwich-type theorem for these integral operators is also considered.

On Certain Classes of Convex Functions

For real numbers and such that , we denote by the class of normalized analytic functions which satisfy the following two sided-inequality: where denotes the open unit disk. We find some relationships involving functions in the class . And we estimate the bounds of coefficients and solve the Fekete-Szego problem for functions in this class. Furthermore, we investigate the bounds of initial coefficients of inverse functions or biunivalent functions.