• 대한수학회지
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• 제40권3호
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• pp.373-390
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• 2003

In this paper we discuss how the dynamics of certain birational maps of the real plane may be studied using complex methods.

• 대한기계학회논문집B
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• 제27권3호
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• pp.319-325
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• 2003

We investigate the spectra and the pseudospectra in plane Poiseuille flow, plane Couette flow and Blasius flow. At subcritical Reynolds number, the spectra are lied strictly inside the stable complex half-plane, but the pseudospectra are lied in the unstable half-plane, reflecting the large linear transient growth that certain perturbations may excite. It means that the smooth flows may become to turbulent even though all the eigenmodes decay monotonically. We found that pseudospectra is one reason that causes subcritical transition in plane Poiseuille flow and plane Couette flow and bypass transition in Blasius flow.

• Structural Engineering and Mechanics
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• 제8권4호
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• pp.421-438
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• 1999

In this paper a practical limit load estimating procedure is proposed for general pipe-elbow structures subjected to complex loading (in-plane and out-of-plane bending, internal pressure and axial force). The explicit calculating formulae are presented on the basis of theoretical analysis combined with numerical simulation. Von Mises' yield criterion is adopted in both analytical and numerical calculation. The finite element examination shows that the method provides a simple but satisfactory prediction of pipe structures in engineering plastic analysis.

• 호남수학학술지
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• 제35권4호
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• pp.717-727
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• 2013

In this paper, we study on a higher order extremal problem relating the Ahlfors map associated to the pair of a finitely connected domain in the complex plane and a point there. We show the power of the Ahlfors map with some error term which is conformally equivalent maximizes any higher order derivative of holomorphic functions at the given point in the domain.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.44.5-44
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• 2002

We propose a concept of the S-eigenvalue(stochastic-eigenvalue) along with corresponding eigenvector, and then we define the PDF corresponding to the S-eigenvalue on a complex plane. Based on the S-eigenvalue concept, we will establish the S-stability concept for linear continuous-time systems with probabilistic uncertainties in the system matrix. These results explicitly characterize how the S-eigenvalue in the complex plane may impose S-stability on S-eigenstructure assignment. Finally, we present numerical examples to illustrate the proposed concept.

• 대한수학회논문집
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• 제33권4호
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• pp.1217-1227
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• 2018

In the paper, we study the growth and fixed point of solutions of high order linear differential equations with entire coefficients of [p, q]-order in the complex plane. We improve and extend some results due to T. B. Cao, J. F. Xu, Z. X. Chen, and J. Liu, J. Tu, L. Z. Shi.

• 대한수학회보
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• 제41권2호
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• pp.307-317
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• 2004

In the setting of the half-plane of the complex plane, we show that for $r\geq0$, the dual space of the weighted bergman spaces B$^{1}{\gamma}$ is the Bloch space of the half-plane and we study some bounded linear operators induced by radial derivatives.

• 대한수학회보
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• 제42권2호
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• pp.387-396
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• 2005

In the setting of the half-plane of the complex plane, we introduce a modified reproducing kernel and we show that for $r>-1/2,\;B^{1,r}-cancellation$ property holds and the Bloch space is the dual space of $B^{1,r}$.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제1권1호
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• pp.65-74
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• 1997

For two dimensional elasticity, we suggest a new complex variable method using the Navier's displacement equation. This method gives alternative displacement and stress formulae to those resulting from the Muskhelishvili's complex function method.

• 한국지반공학회논문집
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• 제36권11호
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• pp.51-60
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• 2020

횡방향의 토압에 저항하는 앵커블록, 흙막이 가설벽체, 레이커 지지블록 등에서 수동토압 산정은 중요한 요소이다. 실무에서는 사용의 편의성으로 인하여 파괴면을 직선으로 가정한 Coulomb과 Rankine의 이론을 사용하여 토압을 산정하는 것이 일반적이다. 하지만 실제 발생하는 수동파괴면은 벽면과 지반의 마찰로 인하여 벽체부근에서는 곡면이고 지표부근에서는 평면이 되는 복합파괴면을 형성한다. 흙막이 구조물의 안정검토에서 저항력으로 산정되는 수동토압이 발생되는 변위는 주동토압이 발생되는 주동변위 보다 커 대부분 구조물의 안정성을 초과하는 변위가 발생하여야 수동토압의 저항력이 발휘되므로 수동토압을 설계에 적용하기 위해서는 허용변위 이내의 임의변위에서 발휘되는 수동측토압의 산정이 매우 중요한 요소이다. 본 연구에서는 복합파괴면을 반영한 한계변위 내의 임의 변위에서 발휘되는 수동측토압을 산정할 수 있는 반경험식을 활용하여 벽체의 세 가지 거동조건에 따라 임의 변위에서 발휘되는 수동토압을 분석하였다.