• 한국산학기술학회논문지
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• 제21권5호
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• pp.337-343
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• 2020

지난 수십 년간, 소형 로봇 가운데 동물과 곤충을 모방한 생체모방 로봇은 인간이 신체적으로 접근할 수 없는 영역에서 특별한 임무를 위해 개발되어 왔다. 최근 들어, 사람의 접근이 제한되는 공간(예 : 고농축 방사능 보관지역, 바이러스 지역, 대테러 위험지역 등)이 늘어나면서 로봇의 활용범위가 더욱 다양해지고 있으며, 과거에는 사람만 가능했던 많은 행위들이 소형 로봇으로의 대체가 시도 되고 있다. 그 중에서도 보행 로봇의 최적 움직임은 이동하는 표면의 특성(예: 거칠기, 곡률, 경사, 재료 등)에 의해 결정될 수 있다. 본 연구에서는 소형 보행 로봇에 적용하기 위한 구조가 간단하고 효율적으로 구동 가능한 압전세라믹 벤더 엑츄에이터를 제안하였다. 유한요소 해석법을 활용한 동적 모델링을 통해 구동원의 형상을 최적화하여 로봇의 이동 성능을 극대화 하였고, 제작과 실험을 통하여 그 결과를 검증하였다. 제작된 엑츄에이터는 무부하 조건에서 최대속도 236mm/s로 이동 하였고, 5g의 부하를 적재하고 156mm/s의 속도로 이동 가능함을 확인 하였다. 제안된 다족형 액추에이터는 수행해야 할 임무와 요구 성능에 따라 모듈식으로 추가가 가능한 장점이 있다.

• 한국세라믹학회지
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• 제40권3호
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• pp.225-228
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• 2003

A Bender typed Multilayer Actuator(BMA) for decreasing the depolarization effect was designed and fabricated. Unlike bimorph and multimorph actuators in which depolarization occurred, the BMA did not generate depolarization because the polarization and the electric field directions are the same. The simulated results indicate that higher displacement of the BMA can be achieved by increasing input voltage. Compared with the multimorph actuator, the proposed actuator is expected to extend a life time as well as acceptable voltage range.

• 한국전기전자재료학회논문지
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• 제29권5호
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• pp.274-278
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• 2016

A road energy harvester was designed and fabricated to convert mechanical energy from the vehicle load to electrical energy. The road energy harvester is composed of 20 piezoelectric materials. This study attempted to evaluate output depending on pavement materials when paving road piezoelectric energy harvester in the road. Harvester is the bender type and is the method of supporting the both ends of piezoelectric material and applying the load in the middle part. Harvester was paved in the type paved with asphalt, type paved with cement and in the exposed type not covering the top of harvester. The output characteristics were compared and evaluated depending on changes in vehicle load and vehicle speed changes. As vehicles, truck (11.9 ton), SUV(1.6 ton) and sedan (1.5 ton) were used and the output characteristics when driving at the interval of 10 km/h from 10 km/h to 100 km/h were evaluated.

• 한국소음진동공학회논문집
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• 제19권1호
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• pp.94-100
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• 2009

This paper proposes a novel curved shape piezoelectric unimorph using a new fabrication method. Instead of using thermal coefficient mismatch, which has been used for conventional processes for curved shape unimorphs, we used pre-stressed substrates and the room temperature adhesion process. A difference of the mechanical strains between the substrate and the piezoelectric layer makes the final manufactured unimorph get curved. Several performance tests of the proposed unimorph actuators were accomplished and the test results showed the proposed unimorph actuator got comparable actuation capability compared with conventional curved shape actuators.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.1067-1071
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• 1997

A new type of gripper for micrometer-size objects is developed using piezoelectric multi-layer benders. It is composed of three chopsticks, two of which are designed to grip micro-objects. The third one is reserved for helping the two when objects are released from the chopsticks. It is well known that a micro object is much easier to grasp than to release it after holding it. The electrostatic force between the chopsticks and an object is believed to be the main cause of adhesion in a dry environment. The surface tension becomes very important when liquids are present or in a liquid. The third auxiliary chopsticks is introduced to solve there surface effects. All the three chopsticks are made of tungsten wires with sharpened ends by etching. When grasping microparts, the two chopsticks are utilized, and, when releasing them anywhere the parts are located, the third one reduces the electrostatic force between the objects and the chopstick may be to help the other two chopsticks to hold an objects in a desired orientation. We constructed the three chopstick gripoer for micro objects and test their function by holding and releasing an object of a diameter of 100 micrometers. We make use of open loop voltage control. The bender displacement resolution is sub-micrometer. The gripping forces, about tens of mN are obtained. The experiment shows that the third auxiliary chopstick functions effectively.

• 한국지반공학회논문집
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• 제21권5호
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• pp.215-223
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• 2005

압전 소자는 전기적 에너지를 기계적 에너지로, 기계적 에너지를 전기적 에너지로 변환하는 물질이다. 피에조 세라믹판을 이용하여 탄성 매질을 겹쳐서 만든 벤더 엘리멘트는 전압을 가하면 변위가 발생하는 특성을 이용하여 액츄에이터로 사용할 수 있고, 반대로 변위가 생기면 전압이 발생하는 압전 현상을 이용하여 변위를 계측하는 트랜스듀서로 활용하여 탄성파 시험의 발진자와 수진기로 실내 시험에서 사용되고 있다. 벤더 엘리멘트를 이용한 탄성파 시험으로 토목재료로 많이 쓰이는 콘크리트의 강성을 측정하였고, 자유단 공진주 시험을 통하여 그 결과를 평가 하였다. 카올리나이트를 이용하여 연약지반을 모사하여 카올리나이트 슬러리의 압밀에 따른 강성 변화를 탄성파 시험을 이용하여 측정할 수 있다. 벤더 엘리멘트는 연약지반에서 전단파 계측에 탁월한 성능을 가지고 있으며, 장래에 연약지반 현장 계측에 사용될 가능성이 큰 것으로 입증되었다.

• 한국기계가공학회지
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• 제16권1호
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• pp.70-76
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• 2017

The pollution problem of fossil energy sources has caused the development of green energy harvesting systems. Piezoelectric energy harvesting technology has been developed under those external environmental factors. A piezoelectric energy harvester can be defined as a device which transforms mechanical vibration or impact energy into electrical energy. Most researches have focused on bender structures. However, these have a limitation on energy efficiency because of the small effective electromechanical coupling factor, around 10%. Therefore, we should look for a new design for energy harvesting. A cymbal energy harvester can be a good candidate for the high-power energy harvester because it uses a high amplification mechanism using endcaps while keeping a higher electromechanical coupling factor. In this research, we focused on energy efficiency improvements of the cymbal energy harvester by changing the polarization direction, because the electromechanical coupling factor of the k33 mode and the k15 mode is larger than that of the k31 mode. Theoretically, we checked the cymbal harvester with radial polarization and it could obtain 6 times larger energy than that with the k31 direction polarization. Furthermore, we verified the theoretical expectation using the finite element method program. Consequently, we could expect a more efficient cymbal harvester with the radial polarization by comparing two polarization directions.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 춘계학술대회 논문요약집
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• pp.38-38
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• 2004

본 연구에서는 미세 물체를 조작하기 위해 젓가락 구조론 가진 3 텅스텐 젓가락형 그립퍼(이후 텅스텐 그립퍼로 명명)와 2 하이브리드 젓가락형 그립퍼(이후 하이브리드형 그립퍼로 명명)를 설계하고 제작하여 장단점을 비교 분석한다. 두 가지 그립퍼의 미세 핑거(Micro fingers)들은 모두 압전 다중 벤더(Piezoelectric Multilayer bender)와 스택(Stack) 구동기로 구동되었다. 그 중 압전 다중벤더는 물체를 잡을 때 굽힘(Bending) 운동을 만들고 스택은 팁간의 끝점이 일치하지 않을 매 일치되도록 잡는 방향과 수직한 방향으로 구동된다.(중략)

• 한국전기전자재료학회논문지
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• 제33권4호
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• pp.276-280
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• 2020

A linear piezoelectric actuator that utilizes the elliptical motion of the two tips of the actuator is proposed. This device is easy to fabricate owing to its simple structure, consisting of three piezo ceramic benders and is suitable for use in micro robotic applications. A π-shaped structure, which was composed of four piezo ceramic benders, was constructed. Two of the benders were positioned on the center of the actuator, and the joints were attached at the ends of the cantilever. The other two benders were positioned on the side of the actuator and were attached between the joint and the tips. The actuator structure was designed to obtain the first bending mode of the horizontal vibration and the vertical vibration at the same frequency, resulting in elliptical motions at the tips. When two sinusoidal wave voltages with a 90-degree phase difference were applied to the two pairs of the actuator benders, elliptical motions were obtained at the tips. The driving characteristics of the prototype actuator were then measured using a laser doppler vibrometer.

• Smart Structures and Systems
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• 제7권4호
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• pp.289-302
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• 2011

In marine clay deposits, naturally formed or artificially reclaimed, the evaluation and monitoring of the consolidation process has been a critical issue in civil engineering practices due to the time frame required for completing the consolidation process, which range from several days to several years. While complementing the conventional iconographic method suggested by Casagrande and recently developed in-situ techniques that measure the shear wave, this study suggests an alternative experimental procedure that can be used to evaluate the consolidation state of marine clay deposits using the shear wave velocity. A laboratory consolidation testing apparatus was implemented with bimorph-type piezoelectric bender elements to determine the effective stress-shear wave velocity (${\sigma}^{\prime}-V_s$) relationship with the marine clays of interest. The in-situ consolidation state was then evaluated by comparing the in-situ shear wave velocity data with the effective stress-shear wave velocity relationships obtained from laboratory experiments. The suggested methodology was applied and verified at three different sites in South Korea, i.e., a foreshore site in Incheon, a submarine deposit in Busan, and an estuary delta deposit in Busan. It is found that the shear wave-based experimental procedure presented in this paper can be effectively and reliably used to evaluate the consolidation state of marine clay deposits.