• Journal of the Chungcheong Mathematical Society
• /
• v.23 no.3
• /
• pp.463-470
• /
• 2010

If P(f, r) is the set of endpoints of radii which have length greater than or equal to r > 0 under a conformal mapping f of the unit disc. Then for large r, the logarithmic capacity of P(f, r), $\frac{1}{\sqrt[2]{r}}{\leq}cap(P(f,r)){\leq}\frac{k}{\sqrt{r}}$. Where k is the positive constant.

• Honam Mathematical Journal
• /
• v.46 no.1
• /
• pp.60-69
• /
• 2024

We consider a special orthonormal basis for the Hardy space of the unit disc to compute the matrix representations of the composition operators with respect to the basis particulary associated to two symbols which are the inverse and the origin symmetry of the Riemann self map in the unit disc, and then we find a certain symmetry of the matrices.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2006.05a
• /
• pp.515-516
• /
• 2006

The goal of total disc replacement is to restore pain-free mobility to a diseased functional spinal unit, by replacing the degenerated disc with a mobile bearing prosthesis. SB Charite III is named commercial product as the Artificial Intervertebral Disc (AID). SB Charite III consists of sliding core and endplate made by Ultra-high Molecular Weight Polyethylene (UHMWPE) and cobalt chrome alloy, respectively. To evaluate the effect of von-Mises stress in AID, and three-dimensional finite element model of AID analysis was preformed for four different loading types of sliding core. Consequently, endplate was compared with a compressive preload at 400N and flexion moment at $3{\sim}9Nm4. Therefore, this research has obtained result that von-Mises stress of sliding core in AID disc by radius curvature.

• Proceedings of the KSR Conference
• /
• 2006.11b
• /
• pp.294-299
• /
• 2006

Korean high speed train(HSR-350x) has adopted a combined electrical and mechanical(friction) braking system. Brake blending control unit(BBCU) controls each brake system to fulfill the required brake performances such as braking distance, deceleration and jerk. When the disc brake is applied in the high speed region, the wear of pad is increased rapidly. In this paper, we discuss the optimized patterns of the disc brake force from the view point of braking energy.

• Bulletin of the Korean Mathematical Society
• /
• v.53 no.2
• /
• pp.325-334
• /
• 2016

In this paper, a boundary version of the Schwarz lemma is investigated. We take into consideration a function $f(z)=z+c_{p+1}z^{p+1}+c_{p+2}z^{p+2}+{\cdots}$ holomorphic in the unit disc and $\|\frac{f(z)}{{\lambda}f(z)+(1-{\lambda})z}-{\alpha}\|$ < ${\alpha}$ for ${\mid}z{\mid}$ < 1, where $\frac{1}{2}$ < ${\alpha}$ ${\leq}{\frac{1}{1+{\lambda}}}$, $0{\leq}{\lambda}$ < 1. If we know the second and the third coefficient in the expansion of the function $f(z)=z+c_{p+1}z^{p+1}+c_{p+2}z^{p+2}+{\cdots}$, then we can obtain more general results on the angular derivatives of certain holomorphic function on the unit disc at boundary by taking into account $c_{p+1}$, $c_{p+2}$ and zeros of f(z) - z. We obtain a sharp lower bound of ${\mid}f^{\prime}(b){\mid}$ at the point b, where ${\mid}b{\mid}=1$.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.21 no.5
• /
• pp.47-53
• /
• 2013

The wide application of disc springs to the designing of mechanical products with space limit is mainly attributable to their property of sustaining large axial load with small displacement. Due to the impediments in expecting the final results caused by the significant differences existing between a single unit and a stacked form, the force-displacement characteristics of a single disc spring and stacked disc springs are mainly examined in this study. In particular, the hysteresis of the series stack and the parallel stack will be investigated through the FE analysis and the analytical results will finally be compared with the acquired experimental data. In the final result, the analytical results were in accordance with the experimental data.

• Communications of the Korean Mathematical Society
• /
• v.32 no.3
• /
• pp.567-578
• /
• 2017

Many scholars studied the boundedness of $Ces{\grave{a}}ro$ operators between $Q_K$ spaces and Bloch spaces of holomorphic functions in the unit disc in the complex plane, however, they did not describe the compactness. Let 0 < ${\alpha}$ < $+{\infty}$, K(r) be right continuous nondecreasing functions on (0, $+{\infty}$) and satisfy $${\displaystyle\smashmargin{2}{\int\nolimits_0}^{\frac{1}{e}}}K({\log}{\frac{1}{r}})rdr<+{\infty}$$. Suppose g is a holomorphic function in the unit disk. In this paper, some sufficient and necessary conditions for the extended $Ces{\grave{a}}ro$ operators $T_g$ between ${\alpha}$-Bloch spaces and $Q_K$ spaces in the unit disc to be bounded and compact are obtained.

• Korean Journal of Mathematics
• /
• v.28 no.4
• /
• pp.699-715
• /
• 2020

In this paper, we give estimates of the Hankel determinant H₂(1) in a novel class 𝓝 (𝜀) of analytical functions in the unit disc. In addition, the relation between the Fekete-Szegö function H₂(1) and the module of the angular derivative of the analytical function p(z) at a boundary point b of the unit disk will be given. In this association, the coefficients in the Hankel determinant b₂, b₃ and b₄ will be taken into consideration. Moreover, in a class of analytic functions on the unit disc, assuming the existence of angular limit on the boundary point, the estimations below of the modulus of angular derivative have been obtained.

• Korean Journal of Plant Tissue Culture
• /
• v.24 no.1
• /
• pp.49-52
• /
• 1997

The effects of several additives on plant regeneration were investigated from leaf disc culture of S. tuberosum cv. Atlantic which is known as poor in regeneration ability. The presence of 2 g/L casein hydrolysate significantly enhanced shoot regeneration. Addition of 10~20 $\mu$M $AgNO_3$, not only increased the frequency of shoot regeneration but also maintained the leaf disc green presumably by the inhibitory action of ethylene accumulation in vitro. Decrease of sucrose levels to below 3% significantly increased the degree of regeneration. The addition of CuSO$_4$had no effect on shoot regeneration.

• Korean Journal of Mathematics
• /
• v.28 no.1
• /
• pp.149-157
• /
• 2020

Some basic properties in connection with generalized relative order and generalized relative lower order of analytic functions in the unit disc have been dicussed in this article.