• 한국해양학회지:바다
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• 제28권1호
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• pp.41-50
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• 2023

용존산소 센서는 그 특성상 시간이 지남에 따라 자료의 변형(drift)이 일어난다. 따라서 용존산소 센서를 이용하여 해수 중의 정확한 용존산소 농도를 측정하기 위해서는 반드시 용존산소 센서의 현장 교정이 필요하다. 현장 교정 방법과 교정을 위한 적절한 시료의 개수 및 용존산소 센서의 실험실 교정주기를 제시하고자 약 1년에 걸쳐 인도양, 태평양, 동해에서 수행된 세 번의 서로 다른 항차에서 총 133개의 용존산소 분석을 위한 시료를 획득하였다. 화학 분석을 통해 얻은 용존산소 분석값과 센서값을 비교 분석하였다. 그 결과 제조사에서 제시하는 센서의 출력전압과 용존산소 분석값을 비교하기보다는 센서에서 주는 최종 농도값과 분석값을 직접 비교하여 얻은 직선의 관계식을 이용하여 센서의 측정값을 교정하는 것이 바람직하고, 박막형 용존산소 센서의 경우 정확한 보정을 위해서는 최소한 30개 이상의 시료에 대한 분석값을 이용해야 약 1% 이내의 정확도 범위 내에서 현장 교정이 가능하다. 또한 CTD용 박막형 용존산소 센서가 70% 이상의 성능을 내기 위해서는 1년 이내의 주기로 실험실 또는 제조사에서 이루어지는 실험실 교정을 수행할 것을 권장한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 정기총회 및 추계학술대회 논문집 학회본부
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• pp.335-337
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• 1993

Offset voltage and drift characteristics of operational amplifier are critical factor to precision AID conversion System. In this study, a method is suggested to design the programmable A/D conversion system which has high resolution and low drift characteristics. First, hardware was designed to reduce the offset voltage of integrator and comparator, and analog switches are connected to reduce the drift characteristics of operational amplifier. And then, a calibration software technique was performed to obtain the stable data from A/D converter. The main advantage of our method is high precision A/D converter can be constructed with low cost and high confidence. Therefore proposed method is expected to be used in the industrial field where a high precision measurement is required.

• Current Optics and Photonics
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• 제8권1호
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• pp.38-44
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• 2024

Under the influence of atmospheric turbulence, a star's point image will shake back and forth erratically, and after exposure the originally small star point will spread into a huge spot, which will affect the ground calibration of the star sensor. To analyze the impact of atmospheric turbulence on the positioning accuracy of the star's center of mass, this paper simulates the atmospheric turbulence phase screen using a method based on a sparse spectrum. It is added to the static-star-simulation device to study the transmission characteristics of atmospheric turbulence in star-point simulation, and to analyze the changes in star points under different atmospheric refractive-index structural constants. The simulation results show that the structure function of the atmospheric turbulence phase screen simulated by the sparse spectral method has an average error of 6.8% compared to the theoretical value, while the classical Fourier-transform method can have an error of up to 23% at low frequencies. By including a simulation in which the phase screen would cause errors in the center-of-mass position of the star point, 100 consecutive images are selected and the average drift variance is obtained for each turbulence scenario; The stronger the turbulence, the larger the drift variance. This study can provide a basis for subsequent improvement of the ground-calibration accuracy of a star sensitizer, and for analyzing and evaluating the effect of atmospheric turbulence on the beam.

• 한국정밀공학회지
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• 제32권7호
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• pp.643-651
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• 2015

Multi-axis magnetic and accelerometer sensor are widely used in consumer product such as smart phones. The vector output of multi-axis sensors have errors on each axis such as offset error, scale error, non-orthogonality. These errors cause many problems on the performance of the applications. In this paper, we designed the effective inline compensation algorithm for calibrating of 3 axis sensors using ellipsoid for mass production of multi-axis sensors. The outputs with those kinds of errors can be modeled by ellipsoid, and the proposed algorithm makes sequential mappings of the virtual ellipsoid to perfect sphere which is calibrated function of the sensor on three-dimensional space. The proposed calibrating process composed of four main stages and is very straightforward and effective. In addition, another imperfection of the sensor such as the drift from temperature can be easily inserted in each mapping stage. Numerical simulation and experimental results shows great performance of the proposed compensation algorithm.

• 산업기술연구
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• 제15권
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• pp.83-91
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• 1995

This paper presents the design of a smart A/D conversion interface used for measuring the load of a truck. Since the load-cell sensor to be used is very sensitive for weight variation, the interface board must have the low-drift and the A/D conversion for accuracy. A new integrator and comparator has been developed to reduce the offset voltage and the drift current of operational amplifiers and has been adapted into the interface board. Also, a software algorithm has been developed to obtain the stable and accrurate A/D conversion. This software includes a RS-485 communication program to control the interface, which gives a capability of backing-up the calibration data and transferring control data. The test and evaluation of the designed interface has been shown as having the better performance compared to the other types of existing weighing systems and sensor instruments.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1814-1819
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• 2004

The purpose of this research is to improve the reliability of automobile navigation system that utilizes the magnetic compass for localization. On account of its sensitiveness against the dynamic external interference of the magnetic field, the electronic compass itself is not accurate enough to be used for the localization compared to the gyro-compass. To overcome this shortcoming, in this research, a robust electronic compass is designed by using two magnetic compasses to cancel out the dynamic interferences efficiently. That is, a dual compass predictive calibration algorithm against irregular external interference of magnetic field is newly proposed and implemented in this paper. When the dynamic interference can be eliminated from the electronic compass, it becomes much accurate than the gyro-based system that suffers from the accumulative drift error. The reliability and performance of the designed system have been verified through the real driving experiments.

• 제어로봇시스템학회논문지
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• 제11권1호
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• pp.27-33
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• 2005

The purpose of this research is to improve the reliability of automobile navigation system that utilizes the magnetic compass for localization. On account of its sensitiveness against the dynamic external interference of the magnetic field, the electronic compass itself is not accurate enough to be used for the localization compared to the gyro-compass. To overcome this shortcoming, in this research, a robust electronic compass is designed by using two magnetic compasses to cancel out the dynamic interences efficiently. That is, a dual compass predictive calibration algorithm against irregular external interference of magnetic field is newly proposed and implemented in this paper. When the dynamic interference can be eliminated from the electronic compass, it becomes much accurate than the gyro-based system that suffers from the accumulative drift error. The reliability and performance of the designed system have been verified through the real driving experiments.

• 센서학회지
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• 제22권6호
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• pp.404-409
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• 2013

We devised calibration procedure for industrial thermometers by a comparison method at the boiling point of nitrogen (${\sim}-196^{\circ}C$). The uncertainty of the calibration was 4 mK (k = 2). As experimentally demonstrated in this work, the effect of the atmospheric pressure on the boiling point of nitrogen can be easily detected by the thermometer. Therefore, when the boiling point of nitrogen is used for calibration of thermometer by comparison, either a reference thermometer must be used to provide the reference temperature or the effect of atmospheric pressure should be carefully considered. The use of a copper block with a large thermal mass soaked into the liquid nitrogen was proven to be more reliable, and the stability of the temperature immersed into the copper block was 1.4 mK. The temperatures at the thermometer wells, evaluated by the crossed-measurement method to compensate for the inaccuracy of the thermometers and the linear drift of the temperature of the copper block, were equivalent within 0.23 mK of standard uncertainty.

• 대한전자공학회논문지SD
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• 제45권11호
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• pp.63-70
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• 2008

본 논문에서는 MEMS 압력 센서의 스마트 센서 시스템을 구현하였다. 피에조 압력센서의 온도 드리프트 문제를 해결하기 위해 외부 환경에 맞춰 시스템이 스스로 발생 오차를 제거하는 보상 알고리즘과 이에 의해 제어되는 프로그래머블한 보정 회로를 제안하였다. 시스템은 신호처리부, 보정 회로, 온도 감지부, 그리고 마이크로프로세서 및 통신부가 SOC으로 구현되었으며, RS-232 인터페이스가 시스템의 모니터링 및 제어를 위해 사용되었다. 구현된 IC의 면적은 $4.38{\times}3.78\;mm^2$이며 $0.35{\mu}m$ CMOS 공정으로 제작되었다. $-40^{\circ}C{\sim}150^{\circ}C$ 온도 범위에서 50 KPa급 MEMS 압력센서의 온도 드리프트 보상 오차는 ${\pm}0.48%$로 측정되었다. 구현된 시스템의 전력소모는 30.5mW로 측정되었다.

• Nuclear Engineering and Technology
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• 제42권2호
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• pp.219-230
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• 2010

In nuclear power plants (NPPs), periodic sensor calibrations are required to assure that sensors are operating correctly. By checking the sensor's operating status at every fuel outage, faulty sensors may remain undetected for periods of up to 24 months. Moreover, typically, only a few faulty sensors are found to be calibrated. For the safe operation of NPP and the reduction of unnecessary calibration, on-line instrument calibration monitoring is needed. In this study, principal component-based auto-associative support vector regression (PCSVR) using response surface methodology (RSM) is proposed for the sensor signal validation of NPPs. This paper describes the design of a PCSVR-based sensor validation system for a power generation system. RSM is employed to determine the optimal values of SVR hyperparameters and is compared to the genetic algorithm (GA). The proposed PCSVR model is confirmed with the actual plant data of Kori Nuclear Power Plant Unit 3 and is compared with the Auto-Associative support vector regression (AASVR) and the auto-associative neural network (AANN) model. The auto-sensitivity of AASVR is improved by around six times by using a PCA, resulting in good detection of sensor drift. Compared to AANN, accuracy and cross-sensitivity are better while the auto-sensitivity is almost the same. Meanwhile, the proposed RSM for the optimization of the PCSVR algorithm performs even better in terms of accuracy, auto-sensitivity, and averaged maximum error, except in averaged RMS error, and this method is much more time efficient compared to the conventional GA method.