• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.173-176
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• 2004

The piezoelectric ceramics for AE sensor piezoelectric devices are desirable to possess higher resonance vibrations. The compositions of $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS) in this work are selected for obtaining especially large electromechanical coupling factor, high mechanical quality factor and high Curie temperature. This ceramic has higher piezoelectric activity and higher electromechanical coupling factor, but the ceramic has lower Curie temperature. The piezoelectric and dielectric characteristics of PZT-PMNS ternary system are investigated as functions of $Ti^{2+}$, $Zi^{2+}$ mol rate. As the results, MPB(morphotropic phase boundary) in this piezoelectric ceramic is x=0.522. Resonance vibrations of PZT ceramics are investigated as ball-bearing drop test. For the use of AE sensor that driving with pre-amplifier, filter circuit after packed this ceramic and an elastic body.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.07a
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• pp.515-518
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• 2004

The Piezoelectric ceramics for AE(Acoustic Emission) sensor are desired large electromechanical coupling factor, high mechanical quality factor and good characteristic resonance frequency. In this study, the empirical formula of specimens is used $0.9Pb(Zr_xTi_{1-x})O_3-0.1Pb(Mn_{1/3}Nb_{1/3}Sb_{1/3})O_3$ (PZT-PMNS). The piezoelectric and dielectric characteristic are investigated by sintering temperature and value of x as functions of $Ti^{2+},\;Zi^{2+}$ mol rate. MPB(morphotropic Phase boundary) is defined in the x=0.522. Because it is appeared to the best piezoelectric and dielectric characteristic in the x=0.522, it can be application by AE sensor. PZT-PMNS ceramics without pre-amplifier and filter are tested for detecting of arc signal. The detection characteristic is evaluated wave form, frequency distribution.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.78-81
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• 2021

Through the smart factory construction project, sensors can be installed in manufacturing production facilities and various process data can be collected in real time. Through this, research on real-time facility anomaly detection is being actively conducted to reduce production interruption due to facility abnormality in the manufacturing process. In this paper, to detect abnormalities in production facilities, the manufacturing data was applied to deep learning models Autoencoder(AE), VAE(Variational Autoencoder), and AAE(Adversarial Autoencoder) to derive the results. Manufacturing data was used as input data through a simple moving average technique and preprocessing process, and performance analysis was conducted according to the window size of the simple movement average technique and the feature vector size of the AE model.

• Journal of Sensor Science and Technology
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• v.14 no.3
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• pp.169-179
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• 2005

A multiplexed bend loss type single-mode fiber-optic sensor system was prepared to measure the displacement of several cm of the civil engineering structures such as many bridges, tunnels and various buildings. This bend loss type fiber-optic sensor used the signal difference between two reflection signals due to various bend losses generating at a pair of optical connectors by using OTDR (optical time domain reflectometer) for measuring displacements. And the experiments were conducted for showing the measurement feasibility on the range of 10 cm, and the multiplexing experiments were also performed to measure the displacements of 5 measuring positions of an object by setting these 5 fiber-optic sensors on a single mode fiber simultaneously.

• 한국지구과학회:학술대회논문집
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• 2010.04a
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• pp.133-133
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• 2010

인공위성 SAR센서는 기존 산란계 해상풍 자료의 낮은 해상도로 인한 여러 한계를 극복함으로써 다양한 해양연구에 있어 필요성과 활용영역이 넓어지고 있다. 이러한 추세에 따라 전세계적으로 다파장 SAR 센서들이 운용 또는 발사 예정에 있음에도 불구하고 현재까지 한반도 주변해에 대한 SAR 해상풍 산출 연구는 C밴드에만 한정되어왔다. 본 연구에서는 L밴드 해상풍 추출알고리즘을 적용하여 L밴드 SAR 영상으로부터 한반도 주변해의 해상풍을 추출하고 산란계 해상풍 자료와 비교 분석을 통해 정확도 특성을 제시하고자 하였다. 2007년 8월 우리나라 동해 지역을 관측한 L밴드 ALOS PALSAR 영상에 대해 L밴드 HH편광 GMF 알고리즘을 적용하여 해상풍을 산출하였다. 산출 해상풍은 동일시점의 산란계 QuikSCAT 자료와 공간적으로 유사한 패턴을 보였으며 두 자료 간의 풍속오차는 3.45m/s로 나타났다. 연구 해역과 같이 강한 바람 범위에서는 산출 해상풍 간의 차이가 크게 나타나며 풍향으로 인한 오차특성이 보인다. 특히 풍속의 경우, 산란계 해상풍이 중간바람 범위에 집중된 것에 비해 L밴드 SAR 산출 해상풍은 강한 바람 범위까지 포함하는 넓은 풍속값 범위를 나타냈다.

• Journal of Korea Society of Industrial Information Systems
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• v.17 no.5
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• pp.1-8
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• 2012

A Smart phone is the one of the mobile devices widely used in our daily life. Moreover, various type of sensing data gathering from smart phone are effectively applicable to recognize of their users or smart phone status. Therefore, many smart phone applications based on sensor data have been actively developed. In this paper, we investigate an unexpected conditions recognition method using continuous sensing data from a single three-axis accelerometer. In addition, we implemented an application using the proposed method which provides the services notifying an abrupt changes of the smart phone conditions. By the experimented results, the application can be useful to protect the smart phone on the user's unaware conditions such as falling or a robbery case.

• Journal of Sensor Science and Technology
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• v.8 no.1
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• pp.69-79
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• 1999

The research and implementation was preformed on high-resolution CCTV camera with CCD exclusive DSP conventional analog signal processor CCTV camera has its limit on auto exposure(AE), auto white balance(AWB), back light compensation(BLC) processing, severe distortion and noise of image, manual control parameter setting, etc. In our study, to resolve the problems in conventional CCTV camera, we made it possible to control AE, AWB, BLC automatically by the use of the DSP, which are used exclusively in the CCD camera produced domestically, and the microcontroller. And we utilized the function of screen display of microcontroller for the user-friendly interface to control CCD camera. And the electronic variable resister(EVR) was used to avoid setting parameters manually in the level of manufacturing process. As the result, It became possible to control parameters of the camera by program. And the cost-down effect was accomplished by improving the reliability of parameter values and reducing the efforts in setting parameters.

• Composites Research
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• v.35 no.2
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• pp.61-68
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• 2022

Composite materials have been used in aerospace industry and many applications because of many advantages such as specific strength and stiffness and corrosion resistance etc. However, it is vulnerable to impacts, these impact lead to formation of cracks in composite laminate and failure of structures. In this paper, we analyzed Mode I fracture toughness of Carbon/Epoxy laminates using acoustic emission signal. DCB test was carried out to analyze Mode I failure characterization of Carbon/Epoxy laminates, and AE sensor was attached to measure AE signal induced by failure of specimen. Fracture toughness was calculated using cumulative AE energy and measured crack length using camera. The calculated fracture toughness was applied in FE model and the result of FE analysis compared with DCB test results. The results show good agreement with between FEM and DCB test results.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.11
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• pp.696-701
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• 2014

In this study, in order to develop coupled vibration mode piezoelectric devices for Acoustic Emission (abbreviated as AE) sensor application with outstanding displacement and piezoelectric properties have been simulated by ATILA FEM program. And, From the results of ATILA simulation, the AE sensor specimen, obtained superior electromechanical coupling factor and displacement, when the size of specimen is $3.45mm{\Phi}{\times}3.45mm$ with ratio of diameter/thickness(${\Phi}/T$)= 1.0. Therefore, AE sensor was fabricated by (Na,K,Li)(Nb,Ta) $O_3$(abbreviated as NKL-NT) system piezoelectric ceramics using coupled vibration mode. The piezoelectric properties of NKL-NT ceramics was exhibited that piezoelectric constant($d_{33}$), piezoelectric voltage constant($g_{33}$) and electro mechanical coupling factor($k_p$) have the excellent values of 261[pC/N], 40.10[$10^{-3}Vm/N$], and 0.44, respectively. The manufactured piezoelectric device with ratio of ${\Phi}/T$= 1.0 indicated the optimum values of resonant frequency(fr)= 556.5[kHz], antiresonant frequency(fa)=631.1[kHz], and effective electromechanical coupling factor(keff)= 0.473. The maximum sensitivity of the coupled vibration mode AE sensor was 55[dB] at the resonant frequency of 75[kHz]. The results show that the coupled vibration mode piezoelectric device is a promising candidate for the application AE sensor piezoelectric device.

• Journal of the Korean Institute of Gas
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• v.11 no.4
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• pp.64-72
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• 2007

Under the AE methods, the valid condition analysis and evaluation the leak etc, resulted by the AE signal pattern on the bottom plate of ground tank at full. In next more, the gradient of accumulation amplitude distribution analysis and comparison the energy, count, and duration time that noise of EMI signal were removed. EMI signal showed height-energy, count, and duration time, it also appeared great gradient of accumulation distribution. Then, with the pure remaining AE signals cluster analysis and location. It would possibly assume of damage with corrosion. Total cluster 20 and energy showed between the maximum 11,990 and 8,565 which is much lower than above figure and event number showed from 8 to 5. Even when it difficult to certify damage by open, as it is raised higher height-sensitivity and threshold by 60 dB. It would possibly presume of location source more accurately.