• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2005년도 Proceedings of ISRS 2005
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• pp.276-279
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• 2005

As the Ubiquitous generation approaches, the importance of the sensor data processing is growing. The data approximation scheme, one of the data processing methods, can be the key of sensor data processing, for it is related not only to the lifetime of sensors but also to the size of the storage. In this paper, we propose the Harmonic Wavelet transform which can minimize the relative error for given sensor data. Harmonic Wavelets use the harmonic mean as a representative which is the minimum point of the maximum relative error between two data values. In addition, Harmonic Wavelets retain the relative errors as wavelet coefficients so we can select proper wavelet coefficients that reduce the relative error more easily. We also adapt the greedy algorithm for local optimization to reduce the time complexity. Experimental results show the performance and the scalability of Harmonic Wavelets for sensor data.

• Tribology and Lubricants
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• 제24권1호
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• pp.34-43
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• 2008

In this paper, an actively controlled aerostatic bearing is studied to overcome the defects of air bearing such as low stiffness and damping coefficients. The actively controlled aerostatic bearing is composed of aerostatic bearings, non-contact type of displacement sensors, piezoelectric actuators and controllers. The cylindrical capacitance sensor (CCS) is used as the displacement sensor. The reason for using CCS instead of the commercial gap sensor is that it can give us the pure error motion of the spindle because it removes the roundness error or the geometric errors in the spindle. The controller is designed by the state space equation and quadratic optimal control theory. The characteristic data of the actively controlled aerostatic bearing system in the frequency domain are presented and the stiffness and damping coefficients of the bearing are mentioned. This paper shows the possibility to reduce the motion error up to 6000 rpm.

• 센서학회지
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• 제8권3호
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• pp.259-264
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• 1999

The $CO_2$ measuring system using infrared sensor has the variance according to the temperature change. Therefore, the temperature compensation should be needed to obtain a reliable measurement. In this study, the sensor module consist of infrared $CO_2$ Sensor, IR Source, pipe and the heater and measuring system has amplifier, A/D converter and microprocessor. And we suggest a method to reduce the error by using the PID temperature control. We use optimum parameters setting of Ziegler & Nichols as well as PID temperature control algorithm for the temperature compensation. In this method, PID optimum parameter is set from dummy time(L) and maximum slope(R). As a result of using this PID temperature control, it is founded that it has the fast response and low steady state error. Therefore, it is certainly proved that this is very suitable algorithm to correct the error on measurement.

• 한국통신학회논문지
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• 제21권6호
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• pp.1596-1603
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• 1996

A single body type of fiber-optic current and voltae sensor using a rare earth doped YIG and a bismuth silicon oxide single crystsl is proposed, which is used for simultaneous measurement of the AC electric current and AC electric voltage over the trasmission lines. Experimental results showed that the fiber-optic current sensor has the maximum 7.5% error within the current range of 0A to 400A, and the fiber-optic voltage sensor has the maximum 0.87% error within the current range of 0V to 400V. The output waveforms of proposed fiber-optic sensor system has a good agreement with output waveforms of conductor current and voltage. Experimental results proved that the output of fiber-optic current sensor is not affected by the electric voltage applied to the fiber-optic voltage sensor, and also, that the output of fiber-optic voltage sensor is not affected by the electric current applied to the fiber-optic current sensor.

• 전자공학회논문지
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• 제51권6호
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• pp.18-25
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• 2014

WBAN(Wireless body area network)에서 신체에 삽입된 센서는 신체의 생물학적인 특성에 의해 일반 센서보다 프레임의 오류가 발생 할 확률이 높아진다. 본 논문에서는 신체에 삽입된 센서의 라이프타임을 향상시키기 위해 삽입 된 센서의 재전송을 외부 센서에서 대신 전송해주는 방법으로 삽입된 센서의 전송을 줄이는 방법을 제시한다. 제시된 LI(Lifetime Increment) 프로토콜은 기존의 CSMA/CA 전송방식에서 데이터 프레임에 외부 센서의 ID를 추가하고, 내부 센서가 전송한 프레임이 재전송이 요구 될 시에는 추가 되어있던 ID의 외부 센서에서 재전송을 책임지는 방법이다. 제안하는 프로토콜의 성능 비교를 위해 WBAN CSMA/CA 전송 방식과 비교한 결과 에너지 소모량이 적어져 라이프 타임이 향상되는 것을 확인하였다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.672-676
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• 2004

In this paper, measuring system of 5 DOF motion errors are proposed using two capacitive type sensor, a straight edge and a laser interfoerometer. Yawing error and pitching error are measured using the laser interferometer, and rolling error is measured by the reversal method using a capacitive type sensor. Linear motion errors of horizontal and vertical direction are measured using the sequential two point method. In this case, influence of angular motion errors is compensated using the previously measured angular motion errors. In the horizontal direction, measuring accuracy is within 0.05 $\mu$m and 0.27 arcsec, and in the vertical direction, it is within 0.15 $\mu$m and 0.5 arcsec. From these results, it is confirmed that the proposed measureing system is very effective to the measurement of 5 DOF motion errors in the ultra precision feed tables.

• 한국군사과학기술학회지
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• 제11권6호
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• pp.30-37
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• 2008

The ARS(Attitude Reference System) calculates an attitude of a vehicle using inertial angular rate sensors and acceleration sensors. The attitude error of ARS increases due to the integration of angular rate sensor output. To reduce the attitude error an acceleration of sensor is used similar to leveling method of INS(Inertial Navigation System). When an acceleration of vehicle is increased, it is difficult to calculate the attitude error using acceleration sensor output. In this paper the estimation method of acceleration due to the attitude error only is proposed. Two methods of the attitude calculation depending on vehicle dynamics and the integration method of these two methods are proposed. To verify its performance the monte carlo simulation is performed and shows that it bounds attitude error of ARS to reasonable level.

• 한국컴퓨터정보학회논문지
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• 제16권12호
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• pp.11-21
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• 2011

임베디드 센서는 낮은 전력량과 신호의 세기로 장애물이나 거리와 같은 공간 환경에 많은 영향을 받으며, 이러한 원인들로 인해 임베디드 센서에서는 노이즈 데이터가 빈번히 발생한다. 임베디드 센서에서 획득하는 정보는 시계열 데이터로 존재하기 때문에 지속적으로 발생하는 시계열 정보에 대한 오류 검출을 실시간적으로 수행하기는 어렵다. 본 논문에서는 임베디드 장치의 물리적 특성을 고려하여 실시간적으로 발생하는 임베디드 센서의 오류 신호를 검출하는 시계열 예측 기반 오류 검출 기법을 제안한다. 본 논문에서 제안한 시계열 예측 기반 오류 검출 기법은 안정 구간 함수를이용하여 현재 발생하는 임베디드장치 신호의 오류를 판단한다. 안정 구간 함수는 임베디드장치 신호를 관측하여 오류 검출을 수행할 때 최근의 신호들에 오류 가중화를 적용함으로써 효과적으로 오류 신호를 탐지할 수 있다. 본 논문에서 제안한 기법을 Intel Lab 신호를 이용하여 실험하였으며, 실험에서 본 논문에서 제안한 기법은 중심이동평균 기법에 비해 26.25%의 정확도 향상을 나타내었다.

• 대한전자공학회논문지TC
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• 제37권2호
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• pp.91-97
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• 2000

본 논문에서는 Feedforward 선형화기 시스템에서 error sensor loop 부분에 적용할 수 있는 새로운 형태의 제어 회로를 제안하였다. 이 제어 회로를 error sensor loop에 적용하였을때 11dB의 입력 전력의 변화 범위에서 안정적으로 동작하였으며, 주 신호가 3차 IM 신호보다 작은 전력 레벨인 -40dB 이상의 감쇄를 갖도록 제어할 수 있었다. 이때 세기 제어 회로에 있어서 제어 오차는 0.05~0.12dB이며, 위상 제어 회로의 제어 오차는 0.016 "이내의 값을 가진다. 이러한 실험 결과를 토대로 입력 전력의 변화, 동작 온도의 변화, 습도, 및 주변 환경의 변화등에 의한 고출력 증폭기의 비선형 특성의 변화를 정밀하게 보상할 수 있음을 이론적으로 검증하였다.

• 센서학회지
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• 제30권1호
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• pp.42-46
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• 2021

In this paper, we describe the development of a force sensor to measure the tool gripping force of the BT50 spindle. The force sensor for a BT50 must be installed inside the gripping force tester; hence, it must be of an appropriate size and have a rated capacity suitable for measuring the gripping force. So, the structure of the force sensor for BT50 was modeled, the size of the sensing part was determined by structural analysis, and the force sensor was manufactured by attaching a strain gauge. The characteristic test results of the manufactured force sensor, indicated that the nonlinearity error, hysteresis error, and reproducibility errors were each within 0.91%, Therefore it was determined that the manufactured force sensor can be used for checking the spindle tool gripping force.