• 한국항공우주학회지
• /
• 제34권1호
• /
• pp.56-64
• /
• 2006

본 논문에서는 전도성 형상기억폴리우레탄 (CSMPU)의 개발과 응용 방법이 연구되었다. 일반적인 형상기억폴리우레탄이 외부 열원에 의해 작동되어 온 반면에, 2004년에 소개된 전도성 형상기억폴리우레탄은 전력에 의해 작동되었다. 전도성 형상기억폴리우레탄 작동기는 일반적인 형상기억폴리우레탄에 카본 나노 튜브를 첨가함으로써 제작되었다. 2004년 연구에서 제작된 전도성 형상기억폴리우레탄이 지닌 핵심 문제점은 카본 나노 튜브의 낮은 분산도였다. 이 논문에서는 분산 문제 해결을 시도하였으며, 일련의 정교한 작업을 통해 향상된 전기적 특성을 지닌 전도성 형상기억폴리우레탄 작동기를 개발하였다. 그리고 개발된 전도성 형상기억폴리우레탄 작동기의 작동 성능을 측정 및 평가하였으며, 초소형비행체 조종면의 제어 실험을 통하여 응용 가능성을 검토하였다.

• International Journal of Precision Engineering and Manufacturing
• /
• 제2권3호
• /
• pp.41-46
• /
• 2001

This paper discusses the feasibility of improving micro-machining accuracy by using two-dimensional(2-D) vibration cutting. Vibration cutting is generated by two piezo actuators arranged orthogonally : one is actuated by a sine curve voltage input, and the other is actuated by a phase-shifted sine curve voltage. A tool attached to the vibrator oscillates in a 2-D elliptical motion, depending on the frequencies, amplitudes, and the phase shifts of two input signals and the workpiece feedrate. Along the elliptical tool locus, cutting is done in the lower part, and non-cutting is done in the upper part. By this way a unique feature of 2-D vibration cutting, that is, air lubrication between a tool and chips, is caused. Another unique feature of 2-D vibration cutting was experimentally verified, that is, some negative thrust force occurs as the direction of chip movement on a tool rake face is reversed. Those features not only help chips flow smoothly and continuously but also reduce cutting force, which results in a higher quality machined surface. Through tool path simulations and experiments under several micro-machining conditions, the 2-D vibration cutting, compared to conventional cutting, was found to result in a great decrease in the cutting force, a much smoother surface, and much less burr.

• 한국정밀공학회지
• /
• 제24권11호
• /
• pp.52-58
• /
• 2007

A cutting device capable of generating various shapes of the cyclic elliptical trajectory of a cutting tool was proposed and micro v-grooving experiments were performed to investigate the characteristics of elliptical vibration cutting (EVC). The proposed cutting device is comprised of a pair of parallel piezoelectric actuators with which harmonic voltages of varying phase difference and magnitude are supplied, creating various shapes of the elliptical tool path. The attributes of the elliptical locus involving the direction of the axis of an ellipse, the rotational direction and amplitudes of a trajectory were fine-tuned for stable operation of the EVC. The EVC characteristics performed with brass and copper revealed reduction in the cutting resistance and suppression of burr formation, resulting in the enhancement of form accuracy of machined micro-features. While the effect of the EVC increases with the increase of excitation frequency and the amplitude, it is found that a change in the cutting force decreases as the amplitude of an elliptical locus increases.

• 정보교육학회논문지
• /
• 제22권2호
• /
• pp.231-238
• /
• 2018

소프트웨어 교육이 교육 현장에서 다루어지기 시작했지만 현장 교사가 활용할 수 있는 피지컬 컴퓨팅 교구 및 수업 가이드라인이 부족한 실정이다. 따라서 본 연구에서는 마이크로비트라는 피지컬 컴퓨팅 교구를 활용한 창의 컴퓨팅 교육 프로그램을 제시하였다. 교육 프로그램에 적용된 동시따응발(MDIAP) 교수학습모형은 동기 유발, 시연하기, 따라하기, 응용하기, 발표하기의 5단계로 구성되었다. 교수-학습 과정은 마이크로비트의 기본 센서와 추가적인 센서, 구동장치를 활용한 메이커 학습으로 구성하여 나선형으로 제시하였다. 이러한 일련의 교수 학습 활동을 통하여 학생들의 창의 컴퓨팅 사고력을 키울 수 있을 것으로 기대한다.

• 한국산학기술학회논문지
• /
• 제12권2호
• /
• pp.623-628
• /
• 2011

마이크로 방전가공은 활용도가 높은 미세가공기술이지만 가공깊이가 증가하면 방전가공 시에 발생하는 가공부산물인 데브리(debris)로 인해 공구 전극과 공작물이 단락되어 방전의 진행이 힘들고 극심한 전극마모가 발생한다. 이를 극복하기 위하여 공구 전극이나 공작물에 진동을 부가하는 진동 플러싱 기술이 개발되었으나 기존의 진동 플러싱 연구는 피에조 액츄에이터를 적용하여 높은 진동수를 발생시키는 것에만 집중하였다. 본 연구에서는 경제적이면서도 유사한 효과를 얻을 수 있는 솔레노이드를 이용한 진동 플러싱을 제안한다. 솔레노이드를 이용한 진동 플러싱은 피에조 액츄에이터를 이용하는 것에 비해 큰 진폭을 얻을 수 있으며 진동수에 대해 독립적으로 설정하는 것이 용이하다. 가공 실험을 통해 솔레노이드를 이용하여 낮은 진동 주파수에서 큰 진폭으로 진동 플러싱하는 방법이 고주파진동 플러싱과 비교하여 경제적이며 충분한 적용효과를 발휘할 수 있음을 확인하였다.

• 한국정밀공학회지
• /
• 제16권3호통권96호
• /
• pp.62-71
• /
• 1999

Integrating micro-machined sensors and actuators on the conventional devices with the copper power lines was incompatible to fabricate the mass produced micro electromechanical system (MEMS) devices. To achieve the compatibility of the wiring method between MEMS parts and devices, we developed the three-dimensional sputter-evaporation system that coats micropatterned thin copper films on the surface of the MEMS element. The system consists of a process chamber, two branch chambers, the substrate holder, and a linear-rotary motion feedthrough. Thin copper film was sputtered and evaporated on the biocompatible polymer, Pellethane$^{circed{R}}$ and silicone, catheter that is 2 mm in diameter and 700 mm in length. The metal film coating technique with three-dimensional thin film sputter-evaporation system was developed to apply the power and signal lines on the micro active endoscope. In this paper, we developed the three-dimensional metal film sputter-evaporation system operated on the low temperature for the biopolymeric substrates used in the medical MEMS devices.

• 대한기계학회논문집A
• /
• 제22권2호
• /
• pp.372-379
• /
• 1998

A new 6 degrees-of-freedom micro stage, based on parallel mechanisms and actuated by using piezoelectric elements, has been developed for the application of micro positioning such as semiconductor manufacturing devices, high precision optical measurement systems, and high accurate machining. The micro stage structure consists of a base platform and an upper platform(stage). The base platform can effectively generates planar motion with yaw motion, while the stage can do vertical motion with roll and pitch motions with respect to the base platform. This separated structure has an advantage of less interference among actuators. The forward and inverse kinematics of the micro stage are discussed. Also, through linearization of kinematic equations about an operating point on the assumption that the configuration of the micro stage remains essentially constant throughout a workspace is performed. To maximize the workspace of the stage relative to fixed frame, an optimal design procedure of geometric parameter is shown. Hardware description and a prototype are presented. The prototype is about 150mm in height and its base platform is approximately 94mm in diameter. The workspace of the prototype is obtained by computer simulation. Kinematic calibration procedure of the micro stage and its results are presented.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2008년도 춘계학술대회 논문집
• /
• pp.731-732
• /
• 2008

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1994년도 하계학술대회 논문집 C
• /
• pp.1271-1273
• /
• 1994

In the field of the optics, precise machine, semiconducting processing, the micro-positioning actuators are required for the control of position in the submicron range. In this study, PNN-PZN-PZT ceramics were fabricated by solid state reaction. The structural, dielectric and electric properties were investigated for sintering condition. The specimen sintered for 1hr at 1,150($^{\circ}C$), had the highest density and dielectric contant.

• Journal of Mechanical Science and Technology
• /
• 제20권4호
• /
• pp.554-560
• /
• 2006

This paper describes the demonstration of successful fabrication and initial characterization of micromachined pressure sensors and micromachined jets (microjets) fabricated for use in macro flow control and other applications. In this work, the microfabrication technology was investigated to create a micromachined fluidic control system with a goal of application in practical fluids problems, such as UAV (Unmanned Aerial Vehicle)-scale aerodynamic control. Approaches of this work include: (1) the development of suitable micromachined synthetic jets (microjets) as actuators, which obviate the need to physically extend micromachined structures into an external flow; and (2) a non-silicon alternative micromachining fabrication technology based on metallic substrates and lamination (in addition to traditional MEMS technologies) which will allow the realization of larger scale, more robust structures and larger array active areas for fluidic systems. As an initial study, an array of MEMS pressure sensors and an array of MEMS modulators for orifice-based control of microjets have been fabricated, and characterized. Both pressure sensors and modulators have been built using stainless steel as a substrate and a combination of lamination and traditional micromachining processes as fabrication technologies.