• 제목, 요약, 키워드: space harmonic analysis

검색결과 146건 처리시간 0.042초

제2고조파발생을 이용한 LiNbO$_3$의 중요 광굴절상수측정 (Determination of photorefrative constants in LiNbO$_3$ using second harmonic generation)

  • 김봉기;이범구
    • 한국광학회지
    • /
    • v.12 no.3
    • /
    • pp.230-234
    • /
    • 2001
  • 반전대칭이 없는 광굴절결정에 있어 위상접합이 만족되지 않은 상태에서 발생된 제2고조파의 세기가 외부전기장에 의존한다는 사실을 이용하여 광굴적결정의 광굴절율 변형현상에 관한 중요상수를 측정할 수 있는 방법을 개발하였다. 마커무늬의 전기장의존도에 관한 근사식을 구하였고 이를 이용하여 제2고조파의 세기변화로부터 공간전하장의 크기를 측정할 수있었다. 실험적으로 congruent $LiNbO_3$에 빛을 두가지 다른 세기로 비추어 유도되는 공간저하장의 시간의존성을 조사하였고 측정결과를 근사식과 비교분석하여 $LiNbO_3$의 광기전력상수, 암전도상수 및 광전도상수를 결정할 수 있었다.

  • PDF

고체지구조석계산에 있어 몇 가지 이론적 고찰 (Some Theoretical Considerations in Body Tide Calculation)

  • 나성호;신영홍;백정호
    • 지구물리와물리탐사
    • /
    • v.14 no.2
    • /
    • pp.133-139
    • /
    • 2011
  • 지구조석을 계산하는데 있어 가장 주요한 항은 달이나 태양에 의한 구면조화차수가 2인 항으로서 지구조석의 약 98%를 이루며, 나머지는 3차 이상의 고차 항들이다. 그런데 차수 3항과 그 이상의 고차수의 항들의 값들은 차수 2항과는 다른 상수가 각각 곱하여져서 계산되어야 한다. 본 연구에서는 조석에 의한 중력변화, 변위 및 수직선의 변화에 대한 바른 계산을 검토하였으며, 필요한 관련상수들을 다시 구하였다. 동일차수내의 다른 계수의 조화함수적 조석주기의존성을 토의하였다. 한편, 지구조석을 계산하는데 관련된 중요한 개념들을 요약 소개하였다.

A State Space Analysis on the Stability of Periodic Orbit Predicted by Harmonic Balance

  • Sung, Sang-Kyung;Lee, Jang-Gyu;Kang, Tae-Sam
    • 제어로봇시스템학회:학술대회논문집
    • /
    • /
    • pp.67.5-67
    • /
    • 2001
  • A closed loop system with a linear plant and nonlinearity in the feedback connection is analyzed for its quasi-static orbital stability by a state-space approach. First a periodic orbit is assumed to exist in the loop which is determined by describing function method for the given nonlinearity. This is possible by selecting a proper nonlinearity and a rigorous justification of the describing function method.[1-3, 18, 20]. Then by introducing residual operator, a linear perturbed model can be formulated. Using various transformations like a modified eigenstructure decomposition, periodic-averaging, charge of variables and coordinate transformation, the stability of the periodic orbit, as a solution of harmonic balance, can be shown by investigating a simple scalar function and result of linear algebra. This is ...

  • PDF

공간고조파법을 이용한 반경방향 영구자석을 갖는 자기커플링의 와전류 손실 해석 (Eddy Current Loss Analysis in Radial Flux Type Synchronous Permanent Magnet Coupling using Space Harmonic Methods)

  • 민경철;강한빛;박민규;조한욱;최장영
    • 전기학회논문지
    • /
    • v.63 no.10
    • /
    • pp.1377-1383
    • /
    • 2014
  • This paper deals with eddy current loss of magnetic coupling with radial permanent magnet (PM) using analytical method such as a space harmonic method. Superposition of two kinds analysis model is used to analyze eddy current loss induced in inner PM and outer PM of magnetic coupling. When the eddy current is induced, the environmental temperature increases, and the permanent magnet(PM) characteristics are degraded because the performance of PM is greatly influenced by temperature rise. Hence, the calculation of eddy current loss becomes an important factor in the magnetic coupling. In order to analyze eddy current loss, first, on the basis of the magnetic vector potential and two-dimensional(2-D) polar-coordinate system, the magnetic field solutions of the radial magnetized PM are obtained. And we obtain the analytical solutions for the eddy current density produced by permanent magnet. Lastly, analytical solutions for eddy current loss are derived by using equivalent, electrical resistance calculated from magnet volume and analytical solution for eddy current density. This analytical results are validated by comparing with the 2-D finite element analysis (FEA).

고속 전진비 조건에서의 로터 진동하중 특성 연구 (Vibratory Loads Behavior of a Rotor in High Advance Ratios)

  • 나덕환;유영현;정성남
    • 한국항공우주학회지
    • /
    • v.46 no.3
    • /
    • pp.237-243
    • /
    • 2018
  • 본 연구에서는 고 전진비 조건의 로터에 대해 전진비 변화에 따른 허브 진동하중의 변화를 예측하고, 블레이드에서 발생하는 구조하중 예측 및 조화 분석을 통하여 구조하중 변화를 고찰하였다. 로터 전진비는 0.40부터 0.71까지 범위를 가지며, NASA에서 수행한 풍동시험 결과에 대해 수치묘사 연구를 수행하였다. 검증한 결과를 토대로 허브 진동하중 및 블레이드 모멘트를 예측하였다. 허브 진동하중은 최초에 증가하다가 전진비가 0.5 이상의 경우에는 변화가 거의 없음을 보여주었다. 블레이드 구조하중은 전진비가 증가할수록 진폭의 크기가 증가하며, 블레이드 모멘트의 조화 분석을 수행한 결과 플랩 모멘트는 3/rev, 래그모멘트는 4/rev의 영향이 매우 크다는 점을 확인하였다. 이는 전진비가 증가할수록 2차 플랩과 2차 래그 모드의 고유진동수가 각각 3/rev와 4/rev에 근접하기 때문인 것으로 파악되었다.

근대 건축공간에서 시공간 개념에 관한 연구 - 근대적 시간의 개념을 중심으로 - (A Study on Time-space of Thesis in modern arcitecture space - Focus on concept of modem time -)

  • 장세연;이성훈
    • 한국실내디자인학회:학술대회논문집
    • /
    • /
    • pp.69-72
    • /
    • 2001
  • We are defined a space as the activities of creating value in harmonic relations between human and environment. After Industrial Revolution, relations between human and space is changing because of speed and visualization's power in contemporary society. We we known information where is far by means of visualization. There is only difference of speed. Movement in space means the line of vision and circulation. But it is tried to think relations between human and space again in result to experience indirectly. This study aims at the analysis of expression of the modem Architecture space in Giedion' Space, Time, Architecture and aesthetic systems applied to it. On the basis of that , this study analyzed the difference of Bergson' consideration from Modern Architecture about movement.

  • PDF

THE DETECTION OF INSTANTANEOUS DISTORTED CURRENT WITH THREE-DIMENSIONAL SPACE VECTOR

  • Mei, Tong;Jie, Tong;Jingpin, Jiangg
    • 전력전자학회:학술대회논문집
    • /
    • /
    • pp.615-619
    • /
    • 1998
  • Active power filter is a kind of device used for compensating instantaneous reactive and harmonic current in three-phase circuits. An essential technology that determines the behavior of an active power filter is the method of detecting the distorted current. Using three-dimensional space vectors, this paper describes a simple method for detecting the distorted current without any coordinate transformation. The effectiveness of the novel method is verified by the theoretical analysis and simulation.

  • PDF

유전알고리즘을 이용한 리니어모터의 설계변수 최적화에 관한 연구 (A study on Optimization of the Design Variables of Linear Motor Using Genetic Algorithm)

  • 주상현;정재한;이상룡
    • 한국정밀공학회지
    • /
    • v.19 no.5
    • /
    • pp.110-117
    • /
    • 2002
  • This paper proposes a optimization of the design variables of linear motor for the improvement of thrust. Especially, this paper treats the shoe, which can be good to flow of a magnetic flux in linear motor. Firstly, this paper uses a space harmonic analysis method(SHAM) based on Fourier series, for analyzing the characteristics of core type linear motor, including slot structure and shoe. And compare the magnetic flux densities of linear motor at air gap with the results of the SHAM and the Finite Element Method(FEM). Secondly, this paper uses a genetic algorithm, which is good to find the global solutions. The design variables are the pole pitch of magnet, the pitch of slot, the height of slot, the width of shoe and the width of magnet. The maximum thrust with optimum design variables is about 247 N which is improved about 16%.

Comparison of the Characteristics in the Surface Mounted Permanent Magnet and Flux Concentrating Coaxial Magnetic Gears Having the Solid Cores

  • Shin, Ho-Min;Chang, Jung-Hwan
    • Journal of Electrical Engineering and Technology
    • /
    • v.13 no.3
    • /
    • pp.1275-1284
    • /
    • 2018
  • The coaxial magnetic gear with the flux concentrating structure is known that it has the torque performance advantage over the coaxial magnetic gear having surface mounted permanent magnet, thanks to the flux focusing effect. But, if the solid cores are used in the modulating pieces and rotor cores to consider the mechanical reliability and cost reduction, the operating torque of the flux concentrating coaxial magnetic gear can be significantly diminished because the iron losses at the solid cores affect the actual transmitted torque. Furthermore, the modulating pieces and rotor cores have different characteristics of the iron losses from one another, because the space harmonic components of the magnetic flux density, which cause the iron losses, are different. Thus, in this paper, we focused on the analysis of the characteristics of the space harmonic components of the magnetic flux density and resultant eddy current losses in the surface mounted PM and flux concentrating coaxial magnetic gears, when these coaxial magnetic gears have the solid cores at the modulating pieces and rotor cores. The characteristics of pull-out torque (static torque), operating torque (dynamic torque), and efficiency are also researched, and compared by the 3D finite element analysis (FEA) and experiment.

해석적 방법을 이용한 표면부착형 영구자석 기기의 회전자 와전류 손실해석 (Eddy-Current Loss Analysis in Rotor of Surface-Mounted Permanent Magnet Machines Using Analytical Method)

  • 최장영;최지환;장석명;조한욱;이성호
    • 전기학회논문지
    • /
    • v.61 no.8
    • /
    • pp.1115-1122
    • /
    • 2012
  • This paper analyzes eddy-current loss induced in magnets of surface-mounted permanent magnet (SPM) machines by using an analytical method such as a space harmonic method. First, on the basis of a two-dimensional (2D) polar coordinate system and a magnetic vector potential, the analytical solutions for the flux density produced by armature winding current are obtained. By using derived field solutions, the analytical solutions for eddy current density distribution are also obtained. Finally, analytical solutions for eddy current loss induced in rotor magnets are derived by using equivalent electrical resistance calculated from magnet volume and analytical solutions for eddy-current density distribution. In particular, the influence of time harmonics in armature current on the eddy current loss is fully investigated and discussed. All analytical results are validated extensively by finite element analysis (FEA).