• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.268-273
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• 2002

A modeling method for the dynamic characteristic analysis of a translationally accelerated trapezoidal cantilever plate is presented in this paper. The equations of motion for the plate are derived and transformed into a dimensionless form. The effects of the inclination angles and the acceleration on the vibration characteristics of the plate are investigated. Incidentally, natural frequency loci veering and associated mode shape variations are observed and discussed

• Wind and Structures
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• 제31권1호
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• pp.43-57
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• 2020

Considering the wind barriers induced aerodynamic characteristic variations of both bridge deck and trains, this paper studies the effects of wind barriers on the safety and stability of trains as they run through an urban rail transit cable-stayed bridge which tends to be more vulnerable to wind due to its relatively low stiffness and lightweight. For the bridge equipped with wind barriers of different characteristics, the aerodynamic coefficients of trains and bridge decks are obtained from wind tunnel test firstly. And then, the space vibration equations of the wind-train-bridge system are established using the experimentally obtained aerodynamic coefficients. Through solving the dynamic equations, one can calculate the dynamic responses both the trains and bridge. The results indicate that setting wind barriers can effectively reduce the dynamic responses of both the trains and bridge, even though more wind forces acting on the bridge are caused by wind barriers. In addition, for urban rail transit cable-stayed bridges located in strong wind environment, the wind barriers are recommended to be set with 20% porosity and 2.5 m height according to the calculation results of cases with wind barriers porosity and height varying in two wide ranges, i.e., 10% - 40% and 2.0 m to 4.0 m, respectively.

• 한국정밀공학회지
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• 제17권1호
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• pp.198-203
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• 2000

In this paper, a numerical analysis is carried out to show the effect of friction farce on the dynamic characteristics of a flow divider valve. The continuity equations and the equation of motion fur spool are numerically solved. The viscous friction force acting on the spool is considered analyzing the Reynolds equation which governs the viscous flow in the clearance gap between the spool and sleeve. Dynamic characteristics are highly affected by the viscous friction farce whose magnitude is relatively small compare with other fluid forces. Therefore present theoretical formulation and numerical scheme can be used generally in designing and performance evaluation of all the hydraulic spool valve.

• 한국정보통신학회논문지
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• 제7권6호
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• pp.1283-1290
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• 2003

PWM Buck AC-AC 컨버터는 최근 들어 전압 또는 전력 레귤레이터, 전자식 변압기, 위상 천이기와 같은 산업현장의 다양한 응용분야에 폭넓게 사용되고 있다. 본 논문에서는 이러한 PWM Buck AC-AC 컨버터의 정적 및 동적 모델링과 완전한 특성 해석을 제시한다. 먼저, 3상의 컨버터 시스템은 DQ 변환 기법에 의하여 모델링 되고 그에 따라 전압이득과 역률과 같은 기본적인 특성식을 구하고 제어를 위한 시스템의 상태 방정식과 전달함수를 구한다. 다음으로, 이러한 해석에 기초하여 매우 빠른 동적 응답을 갖도록 순시적인 듀티 변동이 가능한 feedforward-feedback 제어기법을 제안한다. 끝으로, 실험결과를 통하여 이러한 모델링과 해석 및 제어가 유효함을 확인할 수 있다.

• 한국광학회지
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• 제4권3호
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• pp.317-322
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• 1993

본 논문에서는 특성행렬을 사용하여 비선형 집적거울 etalon의 입출력 특성을 해석하는 방법을 제시한다. 빛의 세기에 따른 매질의 굴절률 및 흡수율의 변화 특성을 알면, 관계식과 특성행렬식을 결합하여 집적거울 etalon의 비선형 특성을 해석할 수 있다. 이 방법은 파장에 따른 각 거울의 반사율(크기와 위상)을 일일이 구하지 않고, etalon의 구조가 주어지면 바로 임의의 파장에서의 etalon의 입출력 특성을 해석할 수 있다. 또한, 특성행렬식을 이용하여 비선형 집적거울 etalon에서의 쌍안정성을 보였다.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.595-608
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• 2018

This paper deals with the lateral - torsional motion of bridges provided with external cables acting as dampers under the action of horizontal dynamic loads or of walking human crowd loads. A three dimensional analysis is performed for the solution of the bridge models. The theoretical formulation is based on a continuum approach, which has been widely used in the literature to analyze bridges. The resulting equations of the uncoupled motion are solved using the Laplace Transformation, while the case of the coupled motion is solved through the use of the potential energy. Finally, characteristic examples are presented and useful results are obtained.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1992년도 추계학술대회 논문집
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• pp.249-254
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• 1992

Hydrostatic Bearings have been applied to ultra high precision machine tools and precision instruments, because of their low friction characteristic, high load carrying capacity and high moving accuracy at all range of speed. In regard to realizing the Hydrostatic Bearing, various restrictors such as capillary, orifice, diaphram valve, spool valve, and etc can be used. However, their stiffness and flexibility are not sufficient in practical use for ultra precision machine tool elements. In this study dynamic equations were derived and the dynamic characteristics were simulated for both orifice and flow control servo valve. Simulation was carried out on the condition that static and sinusoidal dynamic loads were applied to the table of CNC jig Boring machine. The simulation results indicate the improvement of the performance of the Bearing system when flow control servo valve has been used as restrictor of Hydrostatic Bearing.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제50권12호
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• pp.592-600
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• 2001

This Paper presents the transient analysis of the single-phase line-start permanent magnet synchronous motor. To analyse the starting characteristics, the dynamic equation which is combined electric dynamic equations with mechanical dynamic equation is used. The electric dynamics are derived from the d-q axis voltages of stator and rotor respectively. Especially, symmetrical components transformation is used to consider unbalanced magnetic field which is produced by single-phase input. Non-linear d-q axis inductances according to current amplitude and current phase angle are calculated by Finite Element Method and applied to lumped parameter circuit. The analysis methods are validated by comparing simulated and experimental results.

• Coupled systems mechanics
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• 제6권4호
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• pp.377-398
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• 2017

The present paper deals with the influence of the inclination of cables' system on the decrease of the lateral-torsional motion because of dynamic loadings. For this goal, a mathematical model is proposed. A 3-D analysis is performed for the solution of the bridge model. The theoretical formulation is based on a continuum approach, which has been widely used in the literature to analyze such bridges. The resulting uncoupled equations of motion are solved using the Laplace Transformation, while the case of the coupled motion is solved through the use of the potential energy. Finally, characteristic examples are presented and useful results are obtained.

• Journal of Electrical Engineering and Technology
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• 제6권5호
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• pp.613-617
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• 2011

In the present paper, a new type of electrical actuator, an electromagnetic force driving actuator (EMFA), applicable to air circuit breaker is developed and analyzed. Transient analysis is performed to obtain the dynamic characteristics of EMFA. The distribution of static magnetic flux is obtained using the finite element method. The coupled problems of electrics and mechanics governing equations are solved using the time-difference method. According to the interception rate of each contactor, investigation of the contactor spring load condition is conducted and applied to the threelink system. Comparisons of the dynamic characteristics of the three-link simulation and experimental data are performed.