• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.194-197
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• 1995

In this study, we performed a modeling for $K^{+}$ ion-exchanged diffused channel waveguide and waveguide-type optical coupler by WKB(Wentzel-Kramer-Brillouim) dispersion equation, field distribution equation of mode and coupled mode theory, and examined the optical-power-dividing of the optical coupler fabricated by using the modeling condition. The optical-power-dividing was observed at the waveguide-type optical coupler with 3[$\mu\textrm{m}$] line-width, 6[$\mu\textrm{m}$] space between channel waveguides, and 3[mm] interaction length.

• Progress in Superconductivity
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• 제6권1호
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• pp.52-55
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• 2004

The inductive coupling theory in serially stacked $Bi_2$$Sr_2$$CaCu_2$$O_{8+x}$ intrinsic Josephson junctions predicts that the lattice structure of the Josephson vortices along the c axis gradually changes from the triangular to the rectangular lattice with increasing the vortex velocity. This lattice transition appears as voltage jumps or sub-branch splitting in the Josephson vortex-flow region of current-voltage characteristics (IVC). We report the IVC in external magnetic fields from 2 to 4 T. The stack, with the lateral size of 1.4${\times}$15 $u\m^2$, was fabricated by using the double-side cleaving technique. The sub-branches in the Josephson vortex-flow region, corresponding to a plasma propagation mode in serially coupled intrinsic Josephson junctions, were also observed in the range of 2∼4T. Switching from one branch to another in Josephson vortex-flow region suggests the structural transition of the moving Josephson vortex lattice.

• 한국소음진동공학회논문집
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• 제17권1호
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• pp.10-16
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• 2007

In this paper, the dynamic stability of a cracked simply supported pipe conveying fluid is investigated. In addition, an analysis of the flutter and buckling instability of a cracked pipe conveying fluid due to the coupled mode(modes combined) is presented. Based on the Euler-Bernouli beam theory, the equation of motion can be constructed by using the Galerkin method. The crack section is represented by a local flexibility matrix connecting two undamaged pipe segments. The stiffness of the spring depends on the crack severity and the geometry of the cracked section. The crack is assumed to be in the first mode of fracture and to be always opened during the vibrations. This results of study will contribute to the safety test and a stability estimation of the structures of a cracked pipe conveying fluid.

• 한국광학회지
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• 제12권5호
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• pp.406-413
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• 2001

측면이 코어 가까이 연마된 단일모드 광섬유 위에 금속박막이 포함된 평면 도파로가 올려진 광섬유-평면도파로의 파장 및 편광 선택성에 관하여 이론 및 실험 결과를 보고한다. 금속 박막이 포함된 평면도파로의 특성을 구하기 위한 간단하지만 정확한 해석기법을 기술하였다. 소자를 1차원으로 등가화 시켜 결합모드 이론으로 소자의 거동을 분석하였다. 금속막의 두께와 최상부층 물질의 굴절률이 동작 특성에 미치는 영향을 측정하였고 그 결과는 설명 하였다.

• Structural Engineering and Mechanics
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• 제14권4호
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• pp.491-504
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• 2002

A state-space method is proposed to analyze the aerodynamically coupled flutter problems of long-span bridges based on the modal coordinates of structure. The theory about complex modes is applied in this paper. The general governing equation of the system is converted into a complex standard characteristic equation in a state space format, which contains only two variables. The proposed method is a single-parameter searching method about reduced velocity, and it need not choose the participating modes beforehand and has no requirement for the form of structure damping matrix. The information about variations of system characteristics with reduced velocity and wind velocity can be provided. The method is able to find automatically the lowest critical flutter velocity and give relative amplitudes, phases and energy ratios of the participating modes in the flutter motion. Moreover, the flutter analysis of Jiangyin Yangtse suspension bridge with 1385 m main span is performed. The proposed method has proved reliable in its methodology and efficient in its use.

• Structural Engineering and Mechanics
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• 제75권2호
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• pp.133-144
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• 2020

This investigation is to study the effect of gravitational field and diffusion on a microstretch thermoelastic medium heating by a non-Gaussian laser beam. The problem was studied in the context of the dual-phase-lag model. The normal mode analysis is used to solve the problem to obtain the exact expressions for the non-dimensional displacement components, the micro-rotation, the stresses, and the temperature distribution. The effect of time parameter, heat flux parameter and gravity response of three theories of thermoelasticity i.e. dual-phase-lag model (DPL), Lord and Shulman theory (L-S) and coupled theory (CT) on these quantities have been depicted graphically for a particular model.

• 한국소음진동공학회논문집
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• 제23권8호
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• pp.742-751
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• 2013

The vibration analysis of a rotating cantilever beam made-up of functionally graded materials is presented based on Timoshenko beam theory. The material properties of the beams are assumed to be varied through the thickness direction following a simple power-law form. The frequency equations, which are coupled through gyroscopic coupling terms, are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. In this study, resulting system of ordinary differential equations shows the effects of power-law exponent, angular speed, length to height ratio and Young's modulus ratio. It is believed that the results will be a reference with which other researchers and commercial FE analysis program, ANSYS can compare their results.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.389-391
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• 2014

The Vibration Analysis of Rotating Inward Beams Considering The Tip-Mass is presented based on Euler-Bernoulli beam theory. The frequency equations, which are coupled through gyroscopic coupling terms, are calculated using hybrid deformation variable modeling along with the Rayleigh-Ritz assumed mode methods. In this study, resulting system of ordinary differential equations shows the effects of angular speed, and Young's modulus ratio. It is believed that the results will be a reference with which other researchers and commercial FE analysis program, ANSYS can compare their results.

• Bulletin of the Korean Chemical Society
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• 제17권2호
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• pp.192-198
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• 1996

We present a theoretical formulation of diffusion process on solid surface based on multidimensional transition state theory (TST). Surface diffusion of single adatom results from hopping processes on corrugated potential surface and is affected by surface vibrations of surface atoms. The rate of rare events such as hopping between lattice sites can be calculated by transition state theory. In order to include the interactions of the adatom with surface vibrations, it is assumed that the coordinates of adatom are coupled to the bath of harmonic oscillators whose frequencies are those of surface phonon modes. When nearest neighbor surface atoms are considered, we can construct Hamiltonians which contain terms for interactions of adatom with surface vibrations for the well minimum and the saddle point configurations, respectively. The escape rate constants, thus the surface diffusion parameters, are obtained by normal mode analysis of the force constant matrix based on the Hamiltonian. The analysis is applied to the diffusion coefficients of W, Ir, Pt and Ta atoms on the bcc(110) plane of W in the zero-coverage limit. The results of the calculations are encouraging considering the limitations of the model considered in the study.

• 한국통신학회논문지
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• 제28권2A호
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• pp.70-79
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• 2003

완전도체면 아래의 유전체와 측면 연마된 광섬유의 소산장 결합 및 전파특성에 대한 해석 연구 결과를 나타내었다. 두 구조에서의 전파특성과 소산장 결합 관계를 해석하기 위해 결합모드 방정식과 혼합 모드(compound-mode) 방정식을 이용하여 코아와 유전체의 굴절률 및 구조의 각 변수에 대한 특성을 나타내었다. 그리고 측면 연마된 광섬유와 완전도체면 아래의 유전체가 결합할 때 일어나는 광섬유에서의 감쇠현상을 비교하기 위하여 감쇠상수를 구하여 함께 비교하였다.