• 대한수학회논문집
• /
• 제30권4호
• /
• pp.429-438
• /
• 2015

In this paper, we discuss how the operational calculus can be exploited to the theory of mixed generating functions. We use operational methods associated with multi-variable Hermite polynomials, Laguerre polynomials and Bessels functions to drive identities useful in electromagnetism, fluid mechanics etc. Certain special cases giving bilateral generating relations related to these special functions are also discussed.

• Kyungpook Mathematical Journal
• /
• 제59권3호
• /
• pp.493-503
• /
• 2019

In the present investigation, we define two new subclasses of analytic and m-fold symmetric bi-univalent functions defined by a linear combination in the open unit disk U. Furthermore, for functions in each of the subclasses introduced here, we establish upper bounds for the initial coefficients ${\mid}a_{m+1}{\mid}$ and ${\mid}a_{2m+1}{\mid}$. Also, we indicate certain special cases for our results.

• 대한수학회보
• /
• 제56권6호
• /
• pp.1511-1524
• /
• 2019

In this paper, we investigate the uniqueness of meromorphic functions of finite order concerning sharing small functions and prove that if f(z) and ${\Delta}_cf(z)$ share a(z), b(z), ${\infty}$ CM, where a(z), b(z)(${\neq}{\infty}$) are two distinct small functions of f(z), then $f(z){\equiv}{\Delta}_cf(z)$. The result improves the results due to Li et al. ([9]), Cui et al. ([1]) and $L{\ddot{u}}$ et al. ([12]).

• 대한수학회논문집
• /
• 제34권3호
• /
• pp.783-797
• /
• 2019

In this paper, we introduce and investigate a subclass ${\Im}_{\Sigma}({\alpha},{\beta},{\gamma})$ of analytic and bi-univalent functions of complex order in the open unit disk U in complex plane. Here, we obtain an upper bound for the second Hankel determinant of the functions belonging to this class. Moreover, several interesting conclusions of the results obtained here are also discussed.

• 대한수학회논문집
• /
• 제34권2호
• /
• pp.573-583
• /
• 2019

This article studies the monotonicity, log-convexity of the modified Lommel functions by using its power series and infinite product representation. Some properties for the ratio of the modified Lommel functions with the Lommel function, sinh and cosh are also discussed. As a consequence, $Tur{\acute{a}}n$ type and reverse $Tur{\acute{a}}n$ type inequalities are given. A Rayleigh type function for the Lommel functions are derived and as an application, we obtain the Redheffer-type inequality.

• Kyungpook Mathematical Journal
• /
• 제61권3호
• /
• pp.495-512
• /
• 2021

We study the value distribution theory of L-functions and completely resolve a question from Yang [10]. This question is related to L-functions sharing three finite values with meromorphic functions. The main result in this paper extends corresponding results from Li [10].

• 호남수학학술지
• /
• 제41권2호
• /
• pp.227-242
• /
• 2019

In the present paper, we derive several sufficient conditions for $Carath{\acute{e}}odory$ functions in the open unit disk ${\mathbb{D}}:=\{z{\in}{\mathbb{C}}:{\mid}z{\mid}<1\}$ under the constraint that the second coefficient of the function is preassigned. And, we obtain some sufficient conditions for strongly starlike functions in ${\mathbb{D}}$.

• 호남수학학술지
• /
• 제42권4호
• /
• pp.701-717
• /
• 2020

We introduced and studied a new class of harmonic univalent functions on unit disc 𝕌. Also we provided coefficient conditions, extreme points and convolution conditions for that class of harmonic univalent functions.

• Journal of applied mathematics & informatics
• /
• 제40권1_2호
• /
• pp.259-266
• /
• 2022

The present investigation is concerned with certain subclasses of alpha-convex functions with fixed point and defined with subordination in the unit disc E = {z :| z |< 1}. The estimates of the first four coefficients for the functions in these classes are obtained. The results due to various authors follow as special cases.

• Journal of applied mathematics & informatics
• /
• 제40권1_2호
• /
• pp.341-350
• /
• 2022

We introduce certain subclasses of bi-univalent functions related to the strongly Janowski functions and discuss the Taylor-Maclaurin coefficients |a₂| and |a₃| for the newly defined classes. Also, we deduce certain new results and known results as special cases of our investigation.