• Kyungpook Mathematical Journal
• /
• 제58권2호
• /
• pp.307-318
• /
• 2018

In this paper, we obtain $Fekete-Szeg{\ddot{o}}$ inequalities for certain class of meromorphic functions f(z) for which $-{\frac{(1-{\frac{{\alpha}}{q}})qzD_qf(z)+{\alpha}qzD_q[zD_qf(z)]}{(1-{\frac{{\alpha}}{q}})f(z)+{\alpha}zD_qf(z)}{\prec}{\varphi}(z)$(${\alpha}{\in}{\mathbb{C}}{\backslash}(0,1]$, 0 < q < 1). Sharp bounds for the $Fekete-Szeg{\ddot{o}}$ functional ${\mid}{\alpha}_1-{\mu}{\alpha}^2_0{\mid}$ are obtained.

• Kyungpook Mathematical Journal
• /
• 제55권2호
• /
• pp.395-410
• /
• 2015

For functions $f(z)=z+a_2z^2+a_3z^3+{\cdots}$ with ${\mid}a_2{\mid}=2b$, $b{\geq}0$, sharp radii of starlikeness of order ${\alpha}(0{\leq}{\alpha}<1)$, convexity of order ${\alpha}(0{\leq}{\alpha}<1)$, parabolic starlikeness and uniform convexity are derived when ${\mid}a_n{\mid}{\leq}M/n^2$ or ${\mid}a_n{\mid}{\leq}Mn^2$ (M>0). Radii constants in other instances are also obtained.

• 대한수학회보
• /
• 제43권1호
• /
• pp.179-188
• /
• 2006

For a given p-valent analytic function g with positive coefficients in the open unit disk $\Delta$, we study a class of functions $f(z) = z^p - \sum\limits{_{n=m}}{^\infty} a_nz^n(a_n{\geq}0)$ satisfying $$\frac 1 {p}{\Re}\;(\frac {z(f*g)'(z)} {(f*g)(z)})\;>\;\alpha\;(0{\leq}\;\alpha\;<\;1;z{\in}{\Delta})$$ Coefficient inequalities, distortion and covering theorems, as well as closure theorems are determined. The results obtained extend several known results as special cases.

• Nonlinear Functional Analysis and Applications
• /
• 제27권2호
• /
• pp.331-347
• /
• 2022

In this paper, we introduce new subclasses of analytic and bi-univalent functions associated with the Mittag-Leffler-type Borel distribution by using the Legendre polynomials. Furthermore, we find estimates on the first two Taylor-Maclaurin coefficients |a₂| and |a₃| for functions in these subclasses and obtain Fekete-Szegő problem for these subclasses. We also state certain new subclasses of Σ and initial coefficient estimates and Fekete-Szegő inequalities.

• 대한수학회논문집
• /
• 제38권4호
• /
• pp.1111-1126
• /
• 2023

In this paper, we define a new subclass of k-uniformly starlike functions of order γ (0 ≤ γ < 1) by using certain generalized q-integral operator. We explore geometric interpretation of the functions in this class by connecting it with conic domains. We also investigate q-sufficient coefficient condition, q-Fekete-Szegö inequalities, q-Bieberbach-De Branges type coefficient estimates and radius problem for functions in this class. We conclude this paper by introducing an analogous subclass of k-uniformly convex functions of order γ by using the generalized q-integral operator. We omit the results for this new class because they can be directly translated from the corresponding results of our main class.

• 한국항공우주학회지
• /
• 제38권1호
• /
• pp.35-41
• /
• 2010

최근의 항공기 개발에 있어 조종면을 복수 개로 분할하여 제어함으로써 예기치 못한 결함 발생 시 안전성 및 생존성을 향상 시킬 수 있는 재형상 제어에 관한 연구가 중요하게 대두되어 왔다. 본 논문은 조종면 결함 시 발생 가능한 조종면의 포화를 고려한 모델예측 제어기법을 이용한 재형상 제어를 다룬다. 모델예측 제어의 내부 모델로는 트림 조건에서 선형화된 운동방정식을 사용하며 조종면의 포화가 발생할 경우에 선형행렬부등식 기반의 반한정 프로그래밍을 이용한 최적화를 수행하며 그 외의 경우에는 모델예측 제어기법을 풀어서 구한 해석적인 해를 사용하는 제어기 구조를 제안한다. 제안된 알고리즘의 성능을 확인하기 위해 임의의 조종면 결함 상황에 대한 비선형 시뮬레이션을 수행하였다.