• 대한전자공학회논문지
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• 제24권5호
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• pp.874-879
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• 1987

An exact wave-optics analysis of wave propagation in thin-film optical waveguide using gyrotropic materials as the substrate or film of the guide is presented for the first time. Based on the Maxwell's equations and the boundary conditions of the guide, the field composition and the boundary conditions of the guide, the field composition and the phase velocity for the eigenmodes of the guide are determined. The field patterns of the guided waves are shown for the eigenmodes of the guides. The present analysos allows a new interpretation in the mode conversion of the thin-film optical waveguides.

• 한국안전학회지
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• 제13권3호
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• pp.80-87
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• 1998

This paper presents a study on the development of discharge model and computer program for assessing the risk of electrostatic discharge(ESD) of charged human body This ESD event is modelled as a two-body problem using spherical conductors, simulating the approach of a charged conductor (human body) to a second conductor (electronic equipment). The charge/discharge process for the model is formulated as a matrix of equations by Maxwell's method. Body potentials, energies and the charge transfer during a discharge are calculated. The developed program, based on the suggested scheme in this paper, is applied to a sample system. The results provide a better understanding of ESD event and demonstrate the usefulness of two-body model in practical applications.

• 대한전기학회논문지
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• 제31권12호
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• pp.173-179
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• 1982

This paper presents a modified quasi-static approximate solution derived from the Maxwell's equations of integral form for the calculation of magnetic shielding effectiveness in a non-uniform enclosure such as metal-clad high-voltage test laboratory. It also describes the simplified relationship between the electrical parameters applicable to the engineering calculations of electromagnetic absorption loss which comprise the resultant effects due to the welding seams and short-circuited slots as well as the shielding material properties. A numerical example shows the fairly good agreements with experimental results measured on the absorption loss vs. incident wave frequency without any unreasonable rapid increase.

• International Journal of Railway
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• 제3권1호
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• pp.14-18
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• 2010

This paper describes design and characteristic analysis of long primary type linear synchronous motor (LSM) for high speed train system. LSM is designed using loading distribution method and magnetic equivalent circuit. For characteristic analysis of LSM, analytical and numerical methods are applied. Analytical method for solving the magnetic field distribution of the analytic model is based on the Maxwell’s equations. Using the characteristic equation and magnetic equivalent circuit, we analyze the effect of variation of parameters, and then we validate the result by comparing with numerical method by finite element method (FEM). We compare the analytical method with numerical method for analyzing the effect by variable parameters. This result will be useful of design and forecast of performance without FEM.

• Structural Engineering and Mechanics
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• 제81권3호
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• pp.335-348
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• 2022

It is well known that after finding the displacement in the structural mechanics, strain and stress can be obtained in the straight-forward process. The main purpose of this paper is to unify the displacement functions for solving the solid body. By performing mathematical operations, three sets of these key relationships are found in this paper. All of them are written in the Cartesian Coordinates and in terms of a simple function. Both analytical and numerical approaches are utilized to validate the correctness of the presented formulations. Since all required conditions for the bodies with self-equilibrated loadings are satisfied accurately, the authors' relations can solve these kinds of problems. This fact is studied in-depth by solving some numerical examples. It is found that a very simple function can be used for each formulation instead of ten different and complex displacement potentials defined by previous studies.

• 한국지반환경공학회 논문집
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• 제13권3호
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• pp.39-51
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• 2012

본 연구에서는 포항이암을 대상으로 다양한 경계조건에서의 creep 시험을 수행하여 이암의 시간의존적 특성을 분석하였으며, 이를 바탕으로 기존에 발표된 creep에 대한 점탄성 모델 및 경험식들과 비교 분석함으로써 더 합리적으로 creep 특성을 평가할 수 있는 방법을 제안하고자 한다. Creep 시험결과를 Griggs(1936), Cottrell(1952) 및 Singh(1975)이 제안한 경험식에 대하여 분석한 결과, 전반적으로 응력수준 및 함수비가 증가할수록 creep 상수가 증가하는 경향을 나타내었다. 또한, Singh의 경험식에 의한 예측치는 실측치와 매우 높은 상관성을 보이고 있는 것을 확인할 수 있었으며, 이로부터 이암의 크리프 거동을 해석함에 있어 Singh의 경험식을 적용함이 바람직할 것으로 판단된다. 유동학적 모델인 Burger 모델에 의한 예측치와 실측치를 비교한 결과, 매우 좋은 일치를 보이고 있음을 알 수 있으며, 이로부터 이암의 크리프 거동을 해석함에 있어 Maxwell 요소와 Kelvin 요소를 직렬로 연결한 Burger 모델을 적용하는 것이 바람직할 것으로 판단된다.

• 한국전자파학회논문지
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• 제27권3호
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• pp.284-290
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• 2016

최근 과학의 발전으로 인해 여러 장소에서 전자기기의 활용도가 높아졌기 때문에 예기치 못한 전자기파로 인한 오작동과 하드웨어와 소프트웨어의 치명적인 손상을 확인할 수 있는 안전 기술들이 요구되었다. 기존의 전자 제품뿐만 아니라 소형화 전자기기들이 복잡도가 높은 대형구조물 안에 비치가 되면서 그에 대한 전자파 영향을 맥스웰 방정식(Maxwell Equation)으로 모두 해석하기에는 여러 한계점을 갖고 있다. 본 논문에서는 대형 구조물에서의 복잡한 전자파 해석을 위해 확률론에 바탕을 둔 PWB(PoWer Balance) Method와 위상학적 모델링을 적용하여 내부의 전파 영향을 해석하고자 한다.

• Smart Structures and Systems
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• 제25권2호
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• pp.219-228
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• 2020

This work presents a modified continuum model to explore and investigate static and vibration behaviors of perforated piezoelectric NEMS structure. The perforated nanostructure is modeled as a thin perforated nanobeam element with Euler-Bernoulli kinematic assumptions. A size scale effect is considered by included a nonlocal constitutive equation of Eringen in differential form. Modifications of geometrical parameters of perforated nanobeams are presented in simplified forms. To satisfy the Maxwell's equation, the distribution of electric potential for the piezoelectric nanobeam model is assumed to be varied as a combination of a cosine and linear functions. Hamilton's principle is exploited to develop mathematical governing equations. Modified numerical finite model is adopted to solve the equation of motion and equilibrium equation. The proposed model is validated with previous respectable work. Numerical investigations are presented to illustrate effects of the number of perforated holes, perforation size, nonlocal parameter, boundary conditions, and external electric voltage on the electro-mechanical behaviors of piezoelectric nanobeams.

• 한국위성정보통신학회논문지
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• 제8권3호
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• pp.20-24
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• 2013

본 논문에서는 HEMP의 개념을 소개하고, 안테나 요소의 배치 변화에 따른 방호 효율성을 분석한다. 높은 주파수의 EMP를 맥스웰 방정식을 이용하여 LOS에서 근사한다. 전자기파 감쇄의 영향을 분석하기 위하여, 차폐룸을 구성하여 측정 데이타를 얻는데 이용한다. 수신 안테나의 거리와 주파수를 변화시켜 차폐 정도를 측정한다. 기준이 되는 미국 규격문서와 측정값을 비교하고 측정방법을 간소화해본다. 차폐룸 내부를 3가지 조건으로 만들어 변화를 차폐 정도를 측정한다. 정방향 측정과 역방향 측정의 차이를 살펴보고 차폐룸 측정에 영향을 미치는 요소를 찾는다.

• Steel and Composite Structures
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• 제20권3호
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• pp.513-543
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• 2016

Third order shear deformation theory is used to evaluate electro-elastic solution of a sandwich plate with considering functionally graded (FG) core and composite face sheets made of piezoelectric layers. The plate is resting on the Pasternak foundation and subjected to normal pressure. Short circuited condition is applied on the top and bottom of piezoelectric layers. The governing differential equations of the system can be derived using Hamilton's principle and Maxwell's equation. The Navier's type solution for a sandwich rectangular thick plate with all edges simply supported is used. The numerical results are presented in terms of varying the parameters of the problem such as two elastic foundation parameters, thickness ratio ($h_p/2h$), and power law index on the dimensionless deflection, critical buckling load, electric potential function, and the natural frequency of sandwich rectangular thick plate. The results show that the dimensionless natural frequency and critical buckling load diminish with an increase in the power law index, and vice versa for dimensionless deflection and electrical potential function, because of the sandwich thick plate with considering FG core becomes more flexible; while these results are reverse for thickness ratio.