• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 추계학술발표대회 논문집
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• pp.191-194
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• 2001

A partially coupled thermo-piezoelectric-mechanical triangular finite element model of composite laminates with surface bonded piezoelectric actuators, subjected to externally applied mechanical load, temperature change load, electric field load is developed. The governing differential equations are obtained by applying the principle of free energy and variational techniques. A higher order zigzag theory displacement field is employed to accurately capture the transverse shear and normal effects in laminated composite plates of arbitrary thickness. Nonconforming shape functions by Specht are employed in the transverse displacement variables. Numerical examples demonstrate the accuracy and efficiency of the proposed triangular plate element.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.1463-1468
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• 2007

This paper presents the possibility of the electric energy harvesting using piezoelectric actuator which is operated by geared motor. The geared motor consisting of oval shape cam and speed controller was operated in the range of 40${\sim}$172rpm. The PZT actuator of $36L{\times}13W{\times}0.6H$ was used for energy harvesting and the results of the theoretical model were verified by comparing it with the measured response of a experimental setup. Experimental study for obtaining the optimal operating conditions, such as displacement variation of the PZT actuator and motor speed variation, was achieved. A power of 0.02mW at the geared motor speed of 172rpm and the PZT actuator maximum displacement of $500{\mu}m$ was measured. In this study, it was confirmed that the wind power can be used for MEMS based sensor operating and windmill health monitoring one.

• 대한기계학회논문집A
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• 제25권11호
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• pp.1697-1704
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• 2001

A finite element model for polarization switching in electro-mechanically coupled materials is proposed and applied to predict the switching behavior of a two-dimensional ferroelectric ceramic. A complicated micro-structure existing in the material is modeled as il continuum body and a simple 3 node triangle finite element with nodal displacement and voltage degrees of freedom is used for a finite element analysis. The elements use nonlinear constitutive equations, switching criterion and kinetic relation, fur representation of material response at strong electric and stress fields. The polarization state of the material is represented by internal variables in each element, which are updated at each simulation step based on the proposed constitutive equations. The model reproduces strain and electric displacement hysteresis loops observed in the material.

• 대한기계학회논문집A
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• 제36권2호
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• pp.149-156
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• 2012

파괴역학에서 가중함수는 응력확대계수를 계산하기 위하여 사용되어진다. 본 논문에서는 균열을 가진 횡등방성 압전재료에 대한 전기-기계적 분석을 행하여 평면변형률 상태의 압전문제를 Leknitskii 해석법으로 풀었고 가중함수이론을 압전재료에 확대 적용하였다. 가중함수이론을 이용하여 응력확대계수와 전기변위확대계수를 구하였다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1995년도 춘계학술대회 논문집
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• pp.40-62
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• 1995

A micro positioning system using piezoelectric actuators have very wide application region such as ultra-precision machine tool optical device measurement system. In order to keep a high precision displacement resolution it to useful to take a position sensor and feedback of the error. From the practical point of view high-resolution displacement sensor systems are very expensive and it is difficult to make such a sensitive sensor work properly in a poor operational environment of industry. In this study a piezo-electric micro-depth control system which does not require position sensor but piezoelectric voltage feedback has been developed. It is driven by hysteresis-considering reference input voltage calculated in advance and actuator/sensor characteristics of piezoelectric materials. From the result of experiments a fast and stable response of micro-depth control system has been achieved and an efficient technique to control the piezoelectric actuator suggested.

• 유공압시스템학회논문집
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• 제5권4호
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• pp.26-31
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• 2008

This paper deals with the issue of position tracking control of a clamp-cylinder for injection moulding machine with electric-hydrostatic drives. A fixed displacement pump is utilized in combination with AC motor in order to directly control a clamp-cylinder. A clamp-cylinder may be required to operate under a variety of operating conditions. Therefore, robust control performance is important in position tracking control applications. In order to accommodate mismatches between the real plant and the model used for controller design, discrete-time sliding mode control is developed by combining a velocity feedforward loop. From tracking control experiments, it is shown that significant reduction in position tracking error is achieved through the use of sliding mode control.

• Structural Engineering and Mechanics
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• 제18권2호
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• pp.195-209
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• 2004

By means of the two-dimensional basic equations of transversely isotropic magneto-electro-elastic media and the strict differential operator theorem, the general solution in the case of distinct eigenvalues is derived, in which all mechanical, electric and magnetic quantities are expressed in four harmonic displacement functions. Based on this general solution in the case of distinct eigenvalues, a series of problems is solved by the trial-and-error method, including magneto-electro-elastic rectangular beam under uniform tension, electric displacement and magnetic induction, pure shearing and pure bending, cantilever beam with point force, point charge or point current at free end, and cantilever beam subjected to uniformly distributed loads. Analytical solutions to various problems are obtained.

• 한국공작기계학회논문집
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• 제18권1호
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• pp.36-41
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• 2009

This paper presents the development of a micro punching system with modified cymbal mechanism. To realize the micro punching, we introduced the hybrid system with a macro moving part and micro punching part. The macro moving part consists of a ball screw, a linear guide and the micro step motor and micro punching part includes the PZT actuators and displacement amplification device with modified cymbal mechanism. The PZT actuator is capable of producing very large force, but they provide only limited displacements which are several micro meters. Thus the displacement amplification device is necessary to make those actuators more efficient and useful. For this purpose, a cymbal mechanism in series is proposed. The finite element method was used to design the cymbal mechanism and to analyze the mode shape of the one. The displacement and mode shape error between the FEM results and experiments are within 10%. A considerable design effort has been focused on optimizing the flexure hinge to increase the output displacement and punching force.

• 한국구조물진단유지관리공학회 논문집
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• 제10권4호
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• pp.160-166
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• 2006

본 연구에서는 광섬유 FBG 센서를 이용, 곡률반경을 고려한 이 방향 변위(Two-Way Displacement)를 측정하여 변형각을 환산함으로써 상대좌표를 구하는 알고리즘을 정립하였으며 이를 이용하면 작은 변형에 대해서도 매우정확하게 상대변위를 구할 수 있음을 알 수 있었다. 이를 확인하기 위해 4.5m높이의 H형강에 고안된 이 방향 광섬유센서를 부착하여 횡 방향으로 외력을 가해서 발생한 변위를 수준측량과 일반적인 전자식 변위계로 동시에 측정하여 각각의 측정성능을 비교분석하였다. 그 결과, 광섬유센서의 분해능은 다른 센서시스템에 비해 월등하였으며 이차원 상대좌표의 측정이 가능함을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1688-1690
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• 2001

The mechanical characteristics of XLPE cable is basic to the installation design. Especially, snake and offset design require accurate coefficient of linear expansion($\alpha$), Young's modulus(E) and bending stiffness(El) of the cable. In this paper, $\alpha$, E and El of 345kV XLPE cable was measured by experimental setup, and verified by measuring axial tension and lateral displacement in snake installation.