• 한국항공우주학회지
• /
• 제39권6호
• /
• pp.517-525
• /
• 2011

차분 진동형 가속도계는 입력 가속도에 따른 공진 주파수의 변화를 감지하는 공진형 센서이다. 이 때 가속도계 전기적 동역학의 수학적 모델링 및 구조 특성의 실험적 검증이 정밀한 제어기 및 높은 양질계수를 가지는 구조 설계에 앞서 필요하게 된다. 본 논문에서는 차분 진동형 가속도계의 공진자, 전극 모듈 및 전치증폭기 등의 전기적 모델링을 제시한다. 이러한 모델링 기법은 공진 주파수, 유효 질량, 유효 강성, 양질 계수 등을 측정함으로써 실험적으로 검증된다. 또한 모델링을 통해 예측된 진폭과 측정된 전치증폭기 출력의 직접적인 비교는 본 연구의 유효성을 보여준다.

• Smart Structures and Systems
• /
• 제19권4호
• /
• pp.361-369
• /
• 2017

Electromechanical impedance method as an efficient tool in Structural Health Monitoring (SHM) utilizes the electromechanical impedance of piezoelectric materials which is directly related to the mechanical impedance of the host structure and will be affected by damages. In this paper, electromechanical impedance of piezoelectric patches attached to simply support rectangular plate is determined theoretically and experimentally in order to detect damage. A pairs of piezoelectric wafer active sensor (PWAS) patches are used on top and bottom of an aluminum plate to generate pure bending. The analytical model and experiments are carried out both for undamaged and damaged plates. To validate theoretical models, the electromechanical impedances of PWAS for undamaged and damaged plate using theoretical models are compared with those obtained experimentally. Both theoretical and experimental results demonstrate that by crack generation and intensifying this crack, natural frequency of structure decreases. Finally, in order to evaluate damage severity, damage metrics such as Root Mean Square Deviation (RMSD), Mean Absolute Percentage Deviation (MAPD), and Correlation Coefficient Deviation (CCD) are used based on experimental results. The results show that generation of crack and crack depth increasing can be detectable by CCD.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제14권5호
• /
• pp.609-614
• /
• 2014

The fringe field effects on the transient characteristics of nano-electromechanical (NEM) memory cells have been discussed by using an analytical model. The influence of fringe field becomes stronger as the size of a cell decreases. By using the proposed model, the dependency of NEM memory transient characteristics on cell parameters has been evaluated.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.73-76
• /
• 2007

Electro-Active paper (EAPap) is a new smart material that has a potential to be used in biomimetic actuator and sensor. It is made by cellulose that is abundant material in nature. EAPap is fascinating with its biodegradability, lightweight, large displacement, high mechanical strength and low actuation voltage. Actuating mechanism of EAPap is known to be the combined effects of ion migration and piezoelectricity. However, the electromechanical actuation mechanisms are not yet to be established. This paper presents the modeling of the actuation behavior of water infused cellulose samples and their composite dielectric constants calculated by Maxwell-Wagner theory. Electro-mechanical forces were calculated using Maxwell stress tensor method. Bending deflection was evaluated from simple beam model and compared with experimental observation, which result good correlation with each other.

• 한국소음진동공학회논문집
• /
• 제17권12호
• /
• pp.1179-1183
• /
• 2007

Electro-Active paper(EAPap) is a new smart material that has a potential to be used in biomimetic actuator and sensor. It is made by cellulose that is abundant material in nature. EAPap is fascinating with its biodegradability, lightweight, large displacement, high mechanical strength and low actuation voltage. Actuating mechanism of EAPap is known to be the combined effects of ion migration and piezoelectricity. However, the electromechanical actuation mechanisms are not yet to be established. This paper presents the modeling of the actuation behavior of water infused cellulose samples and their composite dielectric constants calculated by Maxwell-Wagner theory. Electro-mechanical forces were calculated using Maxwell stress tensor method. Bending deflection was evaluated from simple beam model and compared with experimental observation, and which result in good correlation with each other.

• 한국소음진동공학회논문집
• /
• 제26권4호
• /
• pp.458-468
• /
• 2016

Electromechanical model for analyzing a multimodal piezoelectric energy harvester comprising three connected beams is presented in this paper. This system consists of three beams which are connected alternately. The piezoelectric layer is only attached to the middle beam. With this special structural configuration, the first, second, and third natural frequencies are congregated so that the energy harvester can generate meaningful amount of power consistently when the main frequency component of the excitation varies around the lowest three natural frequencies of the harvester. To investigate the dynamic and electric response of the piezoelectric energy harvester, an electromechanical model is developed using the Kane's method and the accuracy of the model is validated by comparing the results obtained with the model with those obtained with the commercial software ANSYS. The results show that the piezoelectric energy harvester comprising three connected beams has much broader power generating frequency range than that of the conventional piezoelectric energy harvester.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2002년도 추계학술대회 논문집
• /
• pp.497-500
• /
• 2002

When one is interested in the dynamics of a mechanical system with electric motors, the force generated by the motor is generally considered as only an applied torque or force independent of mechanical state variables such as velocity. For a system operated in non-steady dynamic conditions, however, the usual analysis approach may fail to predict some characteristics in the dynamic behaviors because of electromechanical coupling effects. In this paper, we propose dynamics analysis model in which dc motor dynamics with the electromechanical coupling effects are embedded to mechanical dynamics models. The do motor is modeled based on its equivalent circuit model and included in the dynamics solving algorithm which we developed before, called generalized recursive dynamics formula. The developed dynamic analysis model is effective and realistic for analysis of electromechanical dynamics of a system with do motors. The developed model is evaluated by constructing and simulating the flexible antennas of an artificial satellite driven by do motors.

• The Korean Journal of Physiology and Pharmacology
• /
• 제23권1호
• /
• pp.63-70
• /
• 2019

We aimed to propose a novel computational approach to predict the electromechanical performance of pre- and post-mitral valve cerclage annuloplasty (MVCA). Furthermore, we tested a virtual estimation method to optimize the left ventricular basement tightening scheme using a pre-MVCA computer model. The present model combines the three-dimensional (3D) electromechanics of the ventricles with the vascular hemodynamics implemented in a lumped parameter model. 3D models of pre- and post-MVCA were reconstructed from the computed tomography (CT) images of two patients and simulated by solving the electromechanical-governing equations with the finite element method. Computed results indicate that reduction of the dilated heart chambers volume (reverse remodeling) appears to be dependent on ventricular stress distribution. Reduced ventricular stresses in the basement after MVCA treatment were observed in the patients who showed reverse remodeling of heart during follow up over 6 months. In the case who failed to show reverse remodeling after MVCA, more virtual tightening of the ventricular basement diameter than the actual model can induce stress unloading, aiding in heart recovery. The simulation result that virtual tightening of the ventricular basement resulted in a marked increase of myocardial stress unloading provides in silico evidence for a functional impact of MVCA treatment on cardiac mechanics and post-operative heart recovery. This technique contributes to establishing a pre-operative virtual rehearsal procedure before MVCA treatment by using patient-specific cardiac electromechanical modeling of pre-MVCA.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권7호
• /
• pp.862-871
• /
• 2003

In this paper, we addressed a modeling for the magnetic levitation stage. This planar magnetic levitator employs four permanent magnet liner motors. Each motor generates vertical force for suspension against gravity, as well as horizontal force for propulsion. Therefore. this stage can generate six degrees of freedom motion by the combination of forces. We derived a mechanical dynamics equation using Lagrangian method and electromechanical dynamics equation by using Co-energy method. Based on the derived dynamics, we can analyze the stage motion that is subject to the input currents and forces.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2007년도 춘계학술대회 논문집
• /
• pp.637-638
• /
• 2007