• Kyungpook Mathematical Journal
• /
• v.45 no.1
• /
• pp.123-130
• /
• 2005

In this paper we discuss a class of analytic functions related to the starlike functions in the unit disk. We prove that this class belongs to the class of close-to-convex functions, we obtain the sharp coefficient upper bounds and distortion theorem of this class, we also get the convexity radius of this class.

• Journal of applied mathematics & informatics
• /
• v.15 no.1_2
• /
• pp.211-225
• /
• 2004

A mixed type dual to a programming problem containing support functions in a objective as well as constraint functions is formulated and various duality results are validated under generalized convexity and invexity conditions. Several known results are deducted as special cases.

• Honam Mathematical Journal
• /
• v.30 no.3
• /
• pp.425-433
• /
• 2008

In this paper, we introduce the concept of p-preconvex sets on preconvexity spaces. We study some properties for p-preconvex sets by using the co-convexity hull and the convexity hull. Also we introduce and study the concepts of pc-convex function, $p^*c$-convex function, pI-convex function and $p^*I$-convex function.

• Honam Mathematical Journal
• /
• v.41 no.1
• /
• pp.101-116
• /
• 2019

In this paper our aim is to establish some geometric properties (like starlikeness, convexity and close-to-convexity) for the generalized and normalized Dini functions. In order to prove our main results, we use some inequalities for ratio of these functions in normalized form and classical result of Fejer.

• Communications of the Korean Mathematical Society
• /
• v.34 no.2
• /
• 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.

• Journal of the Korean Mathematical Society
• /
• v.58 no.4
• /
• pp.949-965
• /
• 2021

The main focus of the present paper is to present new set of sufficient conditions so that the normalized form of the Mittag-Leffler and Wright functions have certain geometric properties like close-to-convexity, univalency, convexity and starlikeness inside the unit disk. Interesting consequences and examples are derived to support that these results are better than the existing ones and improve several results available in the literature.

• Kyungpook Mathematical Journal
• /
• v.13 no.1
• /
• pp.37-40
• /
• 1973

• Kyungpook Mathematical Journal
• /
• v.15 no.2
• /
• pp.265-269
• /
• 1975

• Journal of the Ergonomics Society of Korea
• /
• v.22 no.3
• /
• pp.27-44
• /
• 2003

An experiment was carried out to compare the suitability in visual tasks between flat and conventional (convex) cathode-ray tube (CRT) displays. The subjects performed visual search tasks during 2-h for detecting target words among distracters presented on the screen. The subjects' visual performance was evaluated with average time and number of errors made to complete the tasks. Visual fatigue after the search tasks was also evaluated in terms of degradations in accommodative power and subjective ratings. Difference was not found in task time between the two displays, but flat CRT showed a lower number of errors than conventional CRT. The difference in number of errors was statistically significant at 0=0.05. Although there was no difference between the displays in degradations of accommodative power, results from the subjective ratings showed that flat CRT yields less fatigue than conventional CRT. The results partially support the hypothesis that panel convexity of CRT displays has a significant effect on the performance and fatigue during visual tasks and thus flat CRT is the better display than conventional one.

• Bulletin of the Korean Mathematical Society
• /
• v.21 no.1
• /
• pp.13-15
• /
• 1984