• 한국수학사학회지
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• 제18권1호
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• pp.85-92
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• 2005

본 연구는 변분법과 조화사상 사이에 잘 알려진 내용을 개관하고, 조화사상의 성질 및 발전 과정을 정리하고, 구면 위의 라플라스 작용소의 기본 성질을 정리하고, 구면 사이의 고유함수 사상을 구성하기 위하여 스펙트럼과 고유함수를 계산하였다.

• Journal of applied mathematics & informatics
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• 제30권5_6호
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• pp.865-869
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• 2012

In [2], D. Gaier has given an estimates of harmonic measure. In this paper, we generalize for the K-quasiconformal mapping the corresponding result.

• 한국소음진동공학회논문집
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• 제20권6호
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• pp.583-592
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• 2010

Equations of motion of thin-walled composite H-type cross-section beams exposed to concentrated harmonic and non-harmonic time-dependent external excitations, incorporating a number of nonclassical effects of transverse shear, primary and secondary warping, and anisotropy of constituent materials are derived. The forced vibration response characteristics of a composite H-type cross-section beam exhibiting the circumferentially asymmetric stiffness(CAS) configuration are exploited in connection with the structural bending-torsion coupling resulting from directional properties of fiber reinforced composite materials.

• 한국재료학회:학술대회논문집
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• 한국재료학회 1998년도 IUMRS-ICEM ABSTRACT BOOK
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• pp.55.1-55
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• 1998

• Structural Engineering and Mechanics
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• 제52권4호
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• pp.787-813
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• 2014

Starting with Hamilton's variational principle, the governing field equations for the steady state response of thin-walled beams under harmonic forces are derived. The formulation captures shear deformation effects due to bending and warping, translational and rotary inertia effects and as well as torsional flexural coupling effects due to the cross section mono-symmetry. The equations of motion consist of four coupled differential equations in the unknown displacement field variables. A general closed form solution is then developed for the coupled system of equations. The solution is subsequently used to develop a family of shape functions which exactly satisfy the homogeneous form of the governing field equations. A super-convergent finite element is then formulated based on the exact shape functions. Key features of the element developed include its ability to (a) isolate the steady state response component of the response to make the solution amenable to fatigue design, (b) capture coupling effects arising as a result of section mono-symmetry, (c) eliminate spatial discretization arising in commonly used finite elements, (d) avoiding shear locking phenomena, and (e) eliminate the need for time discretization. The results based on the present solution are found to be in excellent agreement with those based on finite element solutions at a small fraction of the computational and modelling cost involved.

• 대한수학회지
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• 제35권4호
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• pp.831-841
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• 1998

We shall discuss on some vanishing theorems of harmonic sections of a Riemannian vector bundle over a compact Riemannian manifold with boundary. In relating the results of H. Donnelly - P. Li ([4]), for special case of harmonic forms satisfying absolute or relative boundary problem, our results improve the vanishing results of T. Takahashi ([9]).

• 전자공학회논문지A
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• 제33A권10호
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• pp.81-89
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• 1996

In this paper, a very efficient CAD algorithm is proposedd where rhodes formulae combined with distributed lowpass prototype filter in order to design the corrugated waveguide harmonic rejection filters accurately. The proposed algorithm resolves effectively the problem of proximity effect without any optimiation or iterative design process by using the internally convexed corrugated structure. A 13-section tapered corrugated lowpass filter has been designed by the proposed algorithm and fabricated. The experimental results are in good agreement with the calculated results.

• 대한기계학회논문집B
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• 제22권11호
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• pp.1610-1624
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• 1998

An axisymmetric jet is forced with two helical fundamental waves of identical frequency spinning in opposite directions and an additional axisymmetric sub harmonic wave. The subharmonic component rapidly grows downstream from subharmonic resonance with the fundamental, significantly depending on the initial phase difference. The variations of the subharmonic amplitude with the initial phase difference show cusp-like shapes. The amplification of the sub harmonic results in 'vortex pairing of helical modes'. Furthermore, azimuthal variation of the amplification induces an asymmetric jet cross-section. When the initial subharmonics is imposed with an initial phase difference close to a critical value, the jet-cross section evolves into a three-lobed shape. One lobe is generated by the enhanced vortex pairing and the other two lobes are generated by the delayed vortex pairing. Thus, it is confirmed that the initial phase difference between the fundamental and the subharmonic plays an important role in controlling the jet cross-section.

• 전기학회논문지P
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• 제58권4호
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• pp.416-421
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• 2009

Recently, the new Korean Tilting Train Express(TTX) which maintains a speed on the curve railway line is developed. Electric railways, including the TTX, have electrical problems that could bring about serious accidents. For such reasons, the electric railway's electrical problems, electrical harmonic and others, have been studied briskly. Thus, TTX's electrical problems also need leading studies because the new Korean TTX will operate earnestly in 2012. The results could be used hereafter diagnosis of it's components and train conditions. In the paper, electrical signals in TTX operation were measured to analyze electrical harmonic. In addition, after the electrical signals were measured to operating mode (coasting mode, acceleration mode and regenerative breaking mode) respectively in test section(Ho-nam line, Chung-buk line, Jung-ang line and Tae-baek line). The electrical harmonics considered operating modes triparted were analysed and evaluated.

• Nonlinear Functional Analysis and Applications
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• 제26권1호
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• pp.157-164
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• 2021

Recently we investigated a type of Hyers-Ulam stability of the Schrödinger equation with the symmetric parabolic wall potential that efficiently describes the quantum harmonic oscillations. In this paper we study a type of Hyers-Ulam stability of the Schrödinger equation when the potential barrier is a quartic wall in the solid crystal models.