• International Journal of Precision Engineering and Manufacturing
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• 제8권2호
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• pp.14-19
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• 2007

Angle sensors based on the principle of autocollimation, which are usually called autocollimators, can accurately measure small tilt angles of a light-reflecting flat surface. This paper describes a prototype micro-angle sensor that is based on the laser autocollimation technique. The new angle sensor is compact and consists of a laser diode as the light source and a quadrant photodiode as a position-sensing device. Because of its concise design, the microangle sensor facilitates dynamic measurements of the angular error motions of a precision stage without influencing the original dynamic properties of the stage. This is because the sensor only requires a small extra target mirror to be mounted on the stage. The sensitivity of the angle detection is independent of the focal length of the objective lens; therefore, an objective lens with a relatively short focal length is employed to reduce the size of the device. The micro-angle sensor uses a single lens for the both the laser collimation and focusing, which distinguishes it from the conventional laser autocollimation method that has separate collimate and objective lenses. The new micro-angle sensor has dimensions of $15.1\times22.0\times14.0mm$ and its resolution is better than 0.1 arc-second The optical design and performance of this micro-angle sensor were verified by experimental results.

• 센서학회지
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• 제25권1호
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• pp.71-78
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• 2016

PPG signal measured by pulse oximeter can measure pulse and the oxygen saturation of arterial blood. But the PPG signal is distorted by finger movement or other movement in the body. To detect pulse from the PPG signal with motion artifact, we use band pass filter(BPF), Independent component analysis(ICA) and nonlinear autocorrelation(NAC). BPF is used to remove DC component and high frequency noise in the PPG signal with motion artifacts. ICA is used to separate pulse signal and motion artifact. However, pulse signal separated by ICA have no choice but to accompany signal distortion because pulse signal and motion artifact are not completely independent. So, we use nonlinear autocorrelation to emphasize the pure pulse signal from the distorted signal.

• 지구물리
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• 제9권2호
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• pp.99-103
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• 2006

3D object recognition independent of translation and rotation using an ultrasonic sensor array, invariant moment vectors and SOFM(Self Organizing Feature Map) neural networks is presented. Using invariant moment vectors of the acquired 16×8 pixel data of square, rectangular, cylindric and regular triangular blocks, 3D objects could be classified by SOFM neural networks. Invariant moment vectors are constant independent of translation and rotation. The recognition rates for the training and testing data were 95.91% and 92.13%, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 C
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• pp.1484-1486
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• 2001

In this study, The underwater object recognition using ultrasonic sensor fabricated with porous PZT-Polymer 3-3 type composites and invariant moment vector and SOFM(Self Organizing Feature Map) neural networks are presented. The recognition rates for the training data and the testing data were 98% and 94%, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1370-1372
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• 1997

In this study, 3-D underwater object recognition using ultrasonic sensor fabricated with porous piezoelectric ceramics and SCL(Simple Competitive Learning) neural networks are presented. The recognition rates for the training data and the testing dara were 96 and 93%, respectively.

• ETRI Journal
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• 제30권1호
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• pp.47-58
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• 2008

In sensor networks, analyzing power consumption before actual deployment is crucial for maximizing service lifetime. This paper proposes an instruction-level power estimator (IPEN) for sensor networks. IPEN is an accurate and fine grain power estimation tool, using an instruction-level simulator. It is independent of the operating system, so many different kinds of sensor node software can be simulated for estimation. We have developed the power model of a Micaz-compatible mote. The power consumption of the ATmega128L microcontroller is modeled with the base energy cost and the instruction overheads. The CC2420 communication component and other peripherals are modeled according to their operation states. The energy consumption estimation module profiles peripheral accesses and function calls while an application is running. IPEN has shown excellent power estimation accuracy, with less than 5% estimation error compared to real sensor network implementation. With IPEN's high precision instruction-level energy prediction, users can accurately estimate a sensor network's energy consumption and achieve fine-grained optimization of their software.

• 조명전기설비학회논문지
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• 제27권2호
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• pp.1-6
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• 2013

In this paper, we implemented a polarimetric strain sensor using a Sagnac birefringence interferometer composed of a polarization-maintaining photonic crystal fiber (PM-PCF). By changing the length of the PM-PCF employed as the sensor head of the proposed sensor, the length dependence of the strain sensitivity was investigated. With respect to 5.0-, 7.5-, and 10.0-cm-long PM-PCFs, strain measurements were done in a measurement range of $0{\sim}6m{\varepsilon}$, and strain sensitivities of ~2.04, ~1.92, and ${\sim}1.73pm/{\mu}{\varepsilon}$ were obtained, respectively. If an ideal PM-PCF with no length dependence of a modal birefringence is used for the proposed sensor, the strain sensitivity is independent of the length of the sensor head (PM-PCF). In the practical PM-PCF used in experiments, however, a shorter PM-PCF has a higher length dependence of the modal birefringence due to its imperfectness and nonuniformity of the internal structure, resulting in a higher length dependence of the strain sensitivity.

• 한국전자통신학회논문지
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• 제12권6호
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• pp.1057-1064
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• 2017

거대자기임피던스 효과를 이용한 자기센서를 사용하여 자화된 금속이물질을 감지할 수 있는 고감도 금속이물질 감지 센서를 구현하였다. 스트립 형태의 센서는 지자기의 영향으로 스트립의 축방향이 놓인 위치에 따라 초기 직류전압은 다르게 나타났지만 접지점에 연결된 스트립에서 멀어질수록 외부 자계에 대한 출력전압이 증가하며 스트립의 축 방향에는 무관함을 나타내었다. 제안하는 자기센서는 고감도 실현을 위하여 능동잡음필터를 적용하여 기저잡음의 반 이상을 제거할 수 있었고 설치된 주변 환경에서 발생하는 전자기 잡음 및 지자기로 부터의 영향을 받지 않고 자화된 금속 이물질을 검출할 수 있음을 보여주었다. 자화된 철구의 경우 5mm 이격거리에서 지름 0.8mm 까지 감지가 가능함을 실험적으로 보여주었다.

• Nuclear Engineering and Technology
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• 제52권7호
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• pp.1452-1461
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• 2020

A triple bubbler sensor was tested in LiCl-KCl molten salt from 450 to 525 ℃ in a transparent furnace to validate thermal-expansion corrections and provide additional molten salt data sets for calibration and validation of the sensor. In addition to these tests, a model was identified and further developed to accurately determine the density, surface tension, and depth from the measured bubble pressures. A unique feature of the model is that calibration constants can be estimated using independent depth measurements, which allow calibration and validation of the sensor in an electrorefiner where the salt density and surface tension are largely unknown. This model and approach were tested using the current and previous triple bubbler data sets, and results indicate that accuracies are as high as 0.03%, 4.6%, and 0.15% for density, surface tension, and depth, respectively.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 추계학술대회 논문집 학회본부
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• pp.268-272
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• 1989

To avoid the use of position sensor or flux sensor in a field oriented induction machine drive system, the terminal quantities are often used to estimate the rotor flux. Since the estimation involves the leakage inductance of the machine, the performance of such systems is sensitive to the variations of leakage. Since estimation of the stator flux is independent of the leakage, the steady state performance of the stator flux oriented system is insensitive to the leakage inductance. In this paper, the torque response of stator flux oriented system is compared to that of rotor flux oriented system by digital simulation. And induction motor sensor less speed control by stator flux oriented method is developed. The performance of the speed estimation is showed by digital simulation.