• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.05a
• /
• pp.587-592
• /
• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair, because the sensor-actuator pair has strictly positive real (SPR) property. In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB sho robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a 'skyhook' damper, but the point sensor-distributed actuator pair with DVFB acts as a 'skyhook' rotational dmaper pair.ational dmaper pair.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.7
• /
• pp.619-625
• /
• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair. because the sensor-actuator pair has strictly positive real (SPR) property In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a Point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB show robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a “skyhook” damper, hut the point sensor-distributed actuator pair with DVFB acts as a “skyhook” rotational damper pair.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.10
• /
• pp.1007-1014
• /
• 2004

This paper presents a study of low frequencies volume velocity vibration control of a smart panel in order to reduce sound transmission. A distributed piezoelectric quadratically shaped polyvinylidene fluoride (PVDF) polymer film is used as a uniform force actuator and an array of $4\;{\times}\;4$ accelerometer is used as a volume velocity sensor for the implementation of a single-input single-output control system. The theoretical and experimental study of sensor-.actuator frequency response function shows that this sensor-actuator arrangement provides a required strictly positive real frequency response function below about 900 Hz. Direct velocity feedback could therefore be implemented with a limited gain which gives reductions of about 15 dB in vibration level and about 8 dB in acoustic power level at the (1,1) mode of the smart panel. It has been also shown that the shaping error of PVDF actuator could limit the stability and performance of the control system.

• The monthly packaging world
• /
• s.295
• /
• pp.87-89
• /
• 2017

경쟁이 심화되고 있는 식품 및 음료시장에서 살아남기 위해 제조사들은 생산속도와 생산효율성 향상에 사활을 걸고 있다. 장비 고장으로 생산라인이 멈추게 되면 수익에 직접적인 타격을 줄 뿐만 아니라 회사 신뢰도에도 영향을 미칠 수 있다. 이 때문에 전체 장비 효율성에 대부분의 제조사들이 집중하고 있다. 미국의 인쇄 및 마킹 전문기업 Videojet은 최근 고객 피드백 연구에서 얻은 결과를 바탕으로 차세대 연속식 잉크젯 프린터 'Videojet 1860'을 선보였다. 특히 이 제품은 4차산업혁명에 발맞춰 IoT기술을 강화해 화제가 되고 있다. Videojet Technologies의 Anthony Blencowe 연속식 잉크젯 프린터 글로벌 사업부 이사와 최신 식음료시장의 트렌드와 포장 및 인쇄에 대한 이야기를 나눠봤다.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2011.04a
• /
• pp.140-143
• /
• 2011

본 연구에서는 준능동형 제진장치로 복합형 제진장치(HMD, Hybrid Mass Damper)의 운용에 요구되는 제어알고리즘 개발에 대한 연구를 진행하였다. 제어력을 산정하기 위한 알고리즘 내장화 과정에서 구조물의 상태를 피드백하기 위해서는 구조물의 가속도를 계측하고 이로부터 변위, 속도를 추정하게 되는데 여기서 발생하는 오차의 문제점을 개선하기 위하여 GPS의 실시간 변위측정기술을 활용하여 변위를 직접 입력하면서 구조물의 응답을 제어할 수 있는 알고리즘을 구성하려 한다. 이 때 측정된 데이터의 값에는 잡음이 발생하고 미분기의 동적특성을 가지고 있는 HMD에 입력신호로 사용하는 경우 상당한 오차가 생기는 변위 되먹임(Feedback)의 문제점을 확인하였다. 이러한 문제점을 개선하기 위해 제진장치 입력신호의 시간간격(Time-interval)을 조정하여 오차를 줄일 수 있는 방안을 제안하였다. 수치해석결과, 입력신호에는 최적의 시간간격(Time-Interval)이 존재하였으며 이를 적용할 경우 건물의 변위와 가속도 응답을 크게 줄일 수 있음을 확인하였다.

• 한국정보교육학회:학술대회논문집
• /
• 2008.01a
• /
• pp.211-216
• /
• 2008

프로그래밍 교육은 학습자의 창의적이고 논리적인 사고력을 함양시키고 문제해결능력을 신장시킬 수 있는 ICT 교육의 한 분야로서 많은 교육적 가치를 가지고 있다. 프로그래밍과 관련된 초등학교 교육내용은 7차 교육과정에서 누락되었지만 2005년 12월에 개정된 초 중등학교 정보통신기술 운영 지침에 따라 초등학교에도 프로그래밍 교육과정이 도입되었다. 따라서 본 논문은 5, 6학년 '정보처리의 이해' 영역의 프로그래밍에 관련된 학습내용을 학년별 연계성을 고려하여 재구성하고 학습 성취에 대한 피드백을 강화하는 프로그래밍 교육을 위한 웹 코스웨어를 설계 하였다. 웹을 기반으로 설계된 이 시스템은 학교나 가정에서의 프로그래밍 교육 기회를 확대시키는 역할을 하며, 학습자가 학습 성취도를 직접 확인하여 자신의 능력에 맞게 학습속도를 조절할 수 있어 자기 주도적 학습 능력이 향상될 것으로 기대된다. 또한 학습자에게 다양한 동기유발 자료와 학습 결과에 대한 적절한 피드백을 제공함으로써 프로그래밍 교육에 대한 흥미와 학습 성취도를 높일 것으로 기대된다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2004.11a
• /
• pp.109-114
• /
• 2004

This paper presents a theoretical and experimental study of a non-collocated pair of piezopolymer PVDF sensor and piezoceramic PZT actuator, which are bonded on a cantilever beam, in order to suppress unwanted vibration at the tip of the beam. The PZT actuator patch was bonded near the clamped part and the PVDF sensor, which was triangularly shaped, was bonded on the other part of the beam. This is because the triangular PVDF sensor is known that it can detect the tip velocity of a cantilever beam. Because the arrangement of the sensor and actuator pair is not collocated and overlapped each other, the pair can avoid so called 'the in-plane coupling'. The test beam is made of aluminum with the dimension of $200\times20\times2mm$, and the two PZT5H actuators are both $20\times20\times1mm$ and bonded on the beam out-of-phase, and the PVDF sensor is $178mm\times6mm\times52{\mu}m$. Before control, the sensor-actuator frequency response function is confirmed to have a nice phase response without accumulation in a reasonable frequency range of up to 5000 Hz. Both the DVFB and displacement feedback strategies made the error signal from the tip velocity (or displacement) sensor is transmitted to a power amplifier to operate the PZT actuator (secondary source). Both the control methods attenuate the magnitude of the first two resonances in the error spectrum of about 6-7 dB.

• Journal of The Korean Association of Information Education
• /
• v.9 no.3
• /
• pp.397-406
• /
• 2005

The goal of this research is to prove the efficiency of direct instruction by developing and applying an ICT teaching and learning course for physical education based on a direct instruction model. The curriculum for physical education requires the instructors example and feedback, and sometimes classes may be difficult to conduct due to reasons such as weather conditions. Also, in actual learning, the application of a learning model is inadequate. In these cases, using an ICT teaching and learning course, experts can show examples instead. The learners are provided with individual and suitable feedback and can make it practical for them by slowing down motions, sectional motion learning, and repetitive learning. It can also enhance the sharing of the instructors teaching and learning methods. Therefore, this research recomposed the commonly used direct teaching and learning methods in physical education in order to make it suitable for ICT utilized lessons. It was recomposed in a procedural model and each level was explicated, and in order to materialize this, an ICT teaching and learning course was developed. This was then applied to a Fifth grade class, and its learning effects were analyzed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.05a
• /
• pp.368-373
• /
• 2003

This paper presents a study of low frequencies volume velocity vibration control of a smart panel in order to reduce sound transmission. A distributed piezoelectric quadratically shaped polyvinylidene fluoride (PVDF) polymer film is used as a uniform force actuator and an array of 4$\times$4 accelerometer is used as a volume velocity sensor for the implementation of a single-input single-output con rot system. The theoretical and experimental study of sensor-actuator frequency response function sho vs that this sensor-actuator arrangement provides a required strictly positive real frequency response function below about 900Hz. Direct velocity feedback could therefore be implemented with a limited gain which gives reductions of about 15㏈ in vibration level and about 8 ㏈ in acoustic power level at the (1, 1) mode of the smart Panel. It has been also shown that the shaping error of PVDF actuator could limit he stability and performance of the control system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.17 no.3 s.120
• /
• pp.264-273
• /
• 2007

A smart panel with structural sensors and actuators for minimizing noise radiation or transmission is described in the paper with the concept of active structural acoustical control. The sensors and actuators are both quadratically shaped piezoelectric polyvinylidene fluoride(PVDF) Polymer films to implement a volume velocity sensor and uniform force actuator respectively. They are collocated on either side of the panel to take advantage of direct velocity feedback(DVFB) strategy, which can guarantee a robust stability and high performance as long as the sensor-actuator response is strictly positive real(SPR). However, the measured sensor-actuator response of the panel showed unexpected result with non-SPR property. In the paper, the reason of the non-SPR property is investigated by theoretical analysis, computer simulation and experimental verification. The investigation reveals that the arrangement of collocated piezoelectric PVDF sensor and actuator pair on a panel is not relevant to get a high feedback gain and good performance with DVFB strategy.