• Proceedings of the Korean Society of Laser Processing Conference
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• 2006.06a
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• pp.135-143
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• 2006

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2011.06a
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• pp.629-630
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• 2011

• Journal of the Korean Society for Precision Engineering
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• v.26 no.7
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• pp.127-133
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• 2009

We present a $3-{\underline{P}}RS$ compliant parallel manipulator actuated by PZTs. The motion ranges are $400-{\mu}m$ translation to the z-direction and 5.7-mrad rotation about any axis on the x-y plane. A mechanical amplifier whose advantage is approximately 5.5 is designed and integrated with flexure revolute and spherical joints in a monolithic way. We evaluated the performance of the system: kinematic and dynamic characteristics. In kinematic point of view, the flexures play the roles of conventional mechanism but any nonlinearity such as dead-zone and backlash, which make it possible to achieve the steady-state resolution less than $0.1{\mu}m$. The system shows resonance near 86 Hz with high magnitude and, therefore, poor transient response. But the settling is faster when the flexures are strained higher.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.3
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• pp.85-91
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• 2007

This study was carried out to minimize the lifting force of a two hinge type stand mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment and maintenance at any preferred position. The unit will be very useful for the mechanism fabricated with a coil spring and disc springs as a torque generator. The maximum and the minimum torque value should be calculated initially for the smooth lift. And the reasonable torque distribution is necessary to prevent any auto lift and auto dropping at any position because the torque generated by coil spring is more sensitive than disc spring in tilting the position. Therefore, the analysis of the coil spring is requisite to issue the specific torque value depending on the distorted angle with securing reliability of a long time storage condition. After the theoretical torque value was calculated, the evaluation was carried out by making a proto-type sample, then distorted angle was updated by experiment. The result of this study can readily be applied to various units for the optimization of the smooth lift.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.762-769
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• 2003

본 연구에서는 적층형 압전소자를 이용하여 초소형 및 슬림형 광디스크 드라이브용 광픽업 구동기를 개발하였다. 최근에 휴대용 정보기기의 급격한 발달로 인해 다양한 형태의 초소형 정보저장기기가 사용되고 있으며 착탈식 형태의 초소형 광디스크를 사용하는 ODD가 개발 중에 있다. 적층 형태의 압전소자와 유연 힌지 형태의 변위 확대기구를 사용하여 구동기의 출력 힘과 허용 변위를 증가시키도록 설계하였다. 압전형 구동기의 동특성을 고려한 모델링과 이론적 해석을 통해 목표 변위와 성능을 만족하도록 설계 변수를 최적화하였고 이를 ANSYS를 이용한 해석과 비교하였다. 상용화된 적층형 압전소자를 이용한 prototype 올 제작하여 실험을 수행하였으며 이론적인 예상 값과 잘 일치함을 보였다. 이와 같은 이론적 해석과 실험 결과를 토대로 높이가 2.5mm이며 15V 에서 $\pm$400$\mu\textrm{m}$의 변위를 갖는 슬림형 및 초소형 ODD에 적합한 압전형 구동기를 설계하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.2
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• pp.98-105
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• 2005

This paper presents the result of the aeroelastic stability test of the small-scaled hingeless hub system with composite paddle blades in hover and forward flight conditions. Excitation tests of hingeless hub system installed in GSRTS(General Small-scale Rotor Test System) at KARI(Korea Aerospace Research Institute) were carried out to get lead-lag damping ratio of blades with flexures as hub flexure. MBA(Moving Block Analysis) technique was used for the estimation of lead-lag damping ratio. First, blades with metal flexures, then with composite flexures of the same dynamic properties of rotor system as metal one were tested. Tests were done on the ground and in the wind tunnel according to the test conditions of hover and forward flight, respectively. Composite flexures were found to have better damping characteristics over metal ones in the non-rotating vibration test, and it was confirmed that the use of composite flexures would give observable improvement in aeroelastic stability compared to metal ones in all test conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.8 no.3
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• pp.131-140
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• 2004

The main objective of the research is to develop an algorithm for the optimum design of two dimensional steel frames using refined plastic hinge analysis which considers material and geometrical nonlinearities. Using developed algorithm, an optimum design was perform without calculating an effective length factor of the column (K-factor). A multi-level discrete optimization technique with two parameters has been developed and employed in the optimum design algorithm. The optimization algorithm is applied to structural design with the objective of minimizing the weight of a structure and with constraints on load limit, frame drift, ductility. Various application example is provided to demonstrate the feasibility, validity and efficiency of the developed program.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.5 s.170
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• pp.121-129
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• 2005

Lever mechanisms are usually employed to enlarge output displacements in precision stages. In this study, theoretical analysis is done for a precision stage employing a lever and flexure hinges, including bending effect. This study presented relations between design parameters and magnification ratio. This study presents optimal values for the parameters to achieve a longer stage displacement. The analysis is verified by finite element analysis. It is found that adjusting stiffnesses can increase the travel range significantly.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.1
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• pp.39-44
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• 2006

Ultra precision positioning mechanism has been widely used on semiconductor manufacturing equipments, optical spectrum analyzers and cell manipulations. Ultra precision positioning mechanism consists of several actuators, sensors, guides and control systems. Its efficiency depends on each performance of components. The object of this study is to design and analyze the micro stage that is one of the equipments embodied in ultra precision positioning mechanism. The micro stage consists of PZT actuators and flexure hinges. The structural design of flexure hinge is optimized by using RSM and FEM. The control factors concerned with the design of flexure hinges of stage and arms are optimized by minimizing the equivalent stress on the hinge and maximizing 1st natural frequency based on RSM and FEM simulation under various kinds of design conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.742-745
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• 2003

Piezoelectric elements driven ultra-precision stages have been used for high accuracy, fast response and high load rapacity. which are allowable to apply the stages to AFMs. Most of the piezoelectric driven stages are guided by flexure hinges for force transmission and mechanical amplification. However the flexure hinge mechanisms cause lack of position accuracy due to coupled and parasitic motions. Hence it is important that the mechanism design of the stage is focused on the stiffness of the flexure hinges to accomplish fast response and hish accuracy without the coupled and parasitic motions. In this study, some constraints for optimal design of a piezoelectric elements driven stage and a design method are proposed. Next, an optimal design is carried out using mathematical calculation. Finally the designed results are verified by FEM.