• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.7
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• pp.1441-1446
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• 2017

In recent, the studies on the systems have been progressing that count the number of people passing through passageway or count people who exist in specific space. The existing people counting systems count the number of people using ultrared sensors, ultrasonic sensors or camera sensors, which can be installed only on pillar or around wall. Though ultrared sensors and ultrasonic sensors is low cost, they are inadequate to detect incoming/outgoing when several pedestrians pass through passageway concurrently. In this paper, we designed a sensor mat using piezoelectric sensors to complement the above-mentioned disadvantage. Also, we implemented the system that detects direction of progress and counts the number of people. The sensor mat detects direction of progress using pressure given on sensors and timing information and counts the number of people when pedestrians pass through on a sensor mat.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1421-1422
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• 2015

본 연구는 스트립 힘센서에 기반한 무구속 호흡측정에서 스트립센서 최적 위치를 고찰하는 것을 주목적으로 한다. 이를 위해 압전센서를 사용하여 스트립 힘센서를 제작하였으며, 머리, 흉부, 복부 아래에 위치시켜 호흡성분을 검출하였다. 호흡성분 측정 정확성은 온도센서를 사용하여 코에서 동시에 측정된 기준 호흡과, 각 위치에서 측정된 결과의 비교를 통해 분석하였다. 결과적으로, 12명의 피험자를 대상으로 실험을 수행한 결과, 스트립센서를 사용하여 측정된 호흡간격은 기준센서 대비 $1.3669{\pm}0.5639$ 초 (머리), $0.9844{\pm}0.6336$ 초 (흉부), $0.7133{\pm}0.5185$ 초 (복부)의 평균절대오차를 보였다. 이는 복부에서 검출된 호흡성분이 기준호흡과 가장 유사함을 보여준다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.11
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• pp.743-748
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• 2017

For diseases that are difficult to detect by conventional imaging techniques, the development of a diagnostic method that allows sensors to be inserted into the human body to aid the diagnosis of local spots of the target tissue, is highly desirable. In particular, it is extremely difficult to determine whether vulnerable plaque can later develop into atherosclerosis using only imaging techniques. However, vulnerable plaques are expected to have slightly different mechanical properties than healthy tissue. In this study, we aim to develop a piezoelectric cantilever-type sensor that can be inserted into the human body and can detect the local mechanical properties of the target tissue. A piezoelectric polymer composite based on $BaTiO_3$ nanoparticles was optimized for fabrication of a piezoelectric cantilever. Next, a micro-cone tip was fabricated at the end of the piezoelectric cantilever by thermal drawing. Finally, stiffness of biological tissue samples was measured with the piezoelectric cantilever sensor for verifying its functionality.

• The Journal of the Acoustical Society of Korea
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• v.26 no.2
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• pp.80-86
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• 2007

We have investigated on the development of 2-2 type piezocomposites that have better piezoelectric activity and lower acoustic impedance than those of conventional piezoceramics. In this study, we have investigated the piezoelectric and acoustic properties of 2-2 type piezocomposites sensor which was fabricated using dice-and-fill technique for the different volume fraction of PZT. The specific acoustic impedance of 2-2 type piezocomposites decreased linearly when PZT volume fraction was decreased. The resonance characteristics measured by an impedance analyzer(HP4194A) were similar to the analysis of finite element method (FEM). The resonance characteristics and the electromechanical coupling factor were the best when the volume fraction PZT was 0.6. It also showed the highest result from the standpoint of sensitivity, bandwidth and ring-down property and so on at the same condition. The specific characteristics show that the 2-2 type piezocomposites turned out to be superior to the ultrasonic sensor composed by single phase PZT.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.471-474
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• 2009

현대 사회는 유비쿼터스와 함께 Intelligent Bridge와 녹색 뉴딜개념의 Energy Birdge 같은 신개념의 교량연구에 주력하고 있다. 따라서 교량 안전관리는 무선 센서노드로 데이터를 송신하고 있으나 센서 전력에 수명제한 베터리와 기후제한 태양열로 공급 문제가 있다. 이에 본 논문에서는 외력에 의해 bending vibration이 일어나면서 판 양면에 양 음의 전하가 띄어 전압, 전류가 발생하는 압전소자를 이용 하였다. 이 압전소자에 발생하는 정현파로 인한 축전 문제와 발전된 전력이 다른 압전소자에게 흘러 전력생산량의 감소 문제는 Bridge Diode를 사용한 R-C회로도를 구성하여 보완하였다. 이 설계를 통하여 차량 하중(외력)의 크기에 변수를 두어 전압발생 차이를 측정하고 일정시간 외력 통해 Capacitor 축전된 양을 검토하였다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.207-210
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• 2002

This paper is concerned with the experiments on the active vibration control of a plate with piezoceramic sensors and actuators. The natural frequencies of the composite plate featured by a piezo-film sensor and piezo-ceramic actuator are calculated by using the modal analysis method. Modal coordinates are introduced to obtain the state equations of the structural system. Six natural frequencies were considered in the modelling, because robust control theory which has inherent robustness to structured uncertainty is adopted to suppress the transients vibrations of a glass fiber reinforced(GFR) composite beam. A robust controller satisfying the nominal performance and robust performance is designed using robust theory based on the structured singular value. Simulations were carried out with the designed controller and effectiveness of the robust control strategy was verified by results.

• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.677-679
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• 2012

다공질 폴리프로필렌 시트는 압전센서 및 VOC 발생이 적은 자동차 내장소재로 주목을 받고 있으며, 특히 경량화를 위한 다공질 폴리프로필렌 시트의 가공기술이 중요하다. 이 연구에서는 기존의 가교형 폴리프로필렌 시트를 활용하여 압출과 사출이 아닌 압연공정과 열처리 발포공정을 접목하였다. 발포를 위한 마스터배치와 폴리프로필렌의 혼합으로 제조된 두께 1mm의 폴리프로필렌시트를 $200^{\circ}C$온도에서 온간압연공정에 의해 0.1-0.2mm 두께로 제조하고, 이를 $200^{\circ}C$에서 5분동안 발포함으로써 기공률 65%의 시트를 제조함으로써 저가의 압전센서 소재로 활용 가능성을 확인하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.220-223
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• 2015

기존의 제품에서는 음악을 들으며 운동하는 과정에서 음악속도에 맞게 운동을 하는 방법을 사용하였다. 사용자가 운동중에 직접 음악 재생을 조절하는 방법은 좀 더 격한 음악을 재생하고자 했을 때 음악을 검색중 사용자의 운동의 흐름이 끊어지는 경우가 빈번하게 발생한다. 그러나 사용자의 걸음 속도를 이용해 음악 재생속도를 더 빠르게 한다면 효율적인 운동이 될 것이다. 본 논문에서는 신발의 깔창에 장착된 1개 이상의 압전센서를 활용하여 아두이노에서 걸음 수를 수집하고 수집된 압전센서 데이터를 이용하여 걸음 수를 이용한 걸음 속도의 측정 과정을 안드로이드 스마트폰에서 처리한다. 이렇게 측정된 걸음 속도를 통해 안드로이드 스마트폰에서 음악 재생 속도를 결정하여 사용자에게 쾌적한 운동 환경을 제공하는 것을 목적으로 한다.

• Journal of Aerospace System Engineering
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• v.13 no.2
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• pp.19-25
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• 2019

To detect the impact location of a structure, the authors' group conducted a study on piezoelectric paint sensor. The piezoelectric paint sensors are used for impact detection due to their inherent characteristics: sensitivity to high-frequency signal and impact. Additionally, the paint sensor can be applied on curved and complex structures where ceramic sensor would not be applicable. Moreover it is a self-powered sensor therefore no need for an external power source. For impact localization, mosaic pattern electrodes were coated on the specimen and the impact signal obtained from any part of the electrode where the impact occurred. If we more precise impact localization is required, the electrodes should be divided into more parts and impact data acquisition conducted in all the points of the electrode. In this paper, we developed a light, cheap and simple multi-channel data acquisition system to aid in data gathering. In total four channels data acquisition have been tested using the ARM Cortex-M3.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.4
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• pp.811-818
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• 1992

The sensor technology has becoming emerging area as the automation process in industry requires higher productivity, better quality, and the reliability. In this research, the dynamic measuring sensor such as piezoelectric accelerometers has been developed. Especially, the research concentrates on a design methodology, an analysis of the structural characteristics, and a method of the performance evaluation. The fabricated piezoelectric accelerometers show that the performance characteristics is better than commercial products available in the current market.