• 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.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2012년도 추계학술대회 논문집
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• pp.568-574
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• 2012

Turbulent boundary layer noise is already a significant contributor to sonar self noise. For developing acoustic window of sonar system to reduce self noise, a parametric study of design factors of acoustic window is presented. Distance of sensor array from acoustic window, material and damping layer are studied as design factors to influence in the characteristics of the transfer function of self noise. As the result these design factors make change the characteristics of transfer function slightly. Among design factors the location of sensor array is most important parameter in the self noise reduction.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.212-213
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• 2008

Ultrasonic fiber sensor is more cost-effective than optical fiber sensor using light. However, optical fiber lines are separately used for sensing. Thus, if it is applied for huge system, it is need many lines of the sensor systems. To overcome this point, novel ultrasonic sensor systems considering wave cancellation and modulation were newly developed. By using this schema, reference-free sensor system can be developed. By using ultrasonic waves of different excitation frequencies, multiple input-signal output sensor system was also developed by applying spectrum analyses. Using the array type sensor system, the leakage of liquid and its evaporation can be monitored successfully.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.318-322
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• 2001

This paper deals with sensing ability of smart sensor that has a sensing ability to distinguish materials according to surface types of smart sensor. We have developed a new signal processing method that can distinguish among different materials. The smart sensor was developed for recognition of materials. We made two types of smart sensors in our experiment. Then, we estimated the ability to recognize objects according to smart sensor type. We estimated the sensing ability of smart sensor with the $R_{SAI}$ method. Experiments and analysis were executed to estimate the ability to recognize objects according to surface types of smart sensor. Sensing ability of smart sensors was evaluated relatively through a new $R_{SAI}$ method. Applications of smart sensors are for finding abnormal conditions of objects (auto-manufacturing), feeling of objects (medical product), robotics, safety diagnosis of structure, etc.etc.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 춘계학술대회논문집
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• pp.587-592
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• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair, because the sensor-actuator pair has strictly positive real (SPR) property. In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB sho robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a 'skyhook' damper, but the point sensor-distributed actuator pair with DVFB acts as a 'skyhook' rotational dmaper pair.ational dmaper pair.

• 한국소음진동공학회논문집
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• 제14권7호
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• pp.619-625
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• 2004

Direct velocity feedback (DVFB) control is known that it offers an unconditional stability with very high performance when the control strategy is applied at a point collocated sensor and actuator pair. because the sensor-actuator pair has strictly positive real (SPR) property In this paper, two types of collocated sensor-actuator pairs are considered for practical active vibration control of a structure. They are a Point collocated sensor-actuator pair and a point sensor-distributed actuator pair. Both pairs with DVFB show robust stability and performance. It is noted that the collocated point sensor-actuator ultimately acts as a “skyhook” damper, hut the point sensor-distributed actuator pair with DVFB acts as a “skyhook” rotational damper pair.

• Progress in Superconductivity
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• 제5권2호
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• pp.98-104
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• 2004

We analyzed a noise-sensitivity profile of a specific SQUID sensor system for the localization of brain activity. The location of a neuromagnetic current source is estimated from the recording of spatially distributed SQUID sensors. According to the specific arrangement of the sensors, each site in the source space has different sensitivity, that is, the difference in the lead field vectors. Conversely, channel noises on each sensor will give a different amount of the estimation error to each of the source sites. e.g., a distant source site from the sensor system has a small lead-field vector in magnitude and low sensitivity. However, when we solve the inverse problem from the recorded sensor data, we use the inverse of the lead-field vector that is rather large, which results in an overestimated noise power on the site. Especially, the spatial sensitivity profile of a gradiometer system measuring tangential fields is much more complex than a radial magnetometer system. This is one of the causes to make the solutions of inverse problems unstable on intervening of the sensor noise. In this study, in order to improve the localization accuracy, we calculated the noise-sensitivity profile of our 40-channel planar SQUID gradiometer system, and applied it as a normalization weight factor to the source localization using synthetic aperture magnetometry.

• 반도체디스플레이기술학회지
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• 제22권4호
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• pp.93-98
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• 2023

As semiconductor devices become highly integrated and process difficulty increases, the need for highly sensitive sensors that can detect micro leaks is increasing. However, the noise contained in the CCD sensor itself acts as an obstacle to detecting fine leaks. In this study, integration time was changed for each condition, the sensor was cooled to 0℃, and the dark voltage level was measured to confirm through experiment the characteristics of the temporal noise included in the CCD sensor, a component of OES (Optical Emission Spectroscopy). When integration time was reduced from 30msec to 10msec, the dark voltage level decreased by about 20.5 % from an average of 151.5mV to 120.5mV. In the case of cooling device, Peltier elements were selected because of their simple structure and small size. During temperature cooling, the target temperature was controlled to within ±0.5℃ through PID control. When cooled from 20℃ to 0℃ using this cooling device, it was confirmed that the dark voltage level decreased by about 7% from an average of 147.0mV to 137.0mV.

• 제어로봇시스템학회논문지
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• 제12권10호
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• pp.1022-1028
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• 2006

A portable ECG sensor module and monitoring system which has the powerline noise reduction and the baseline wander removal is proposed. A small-szie ECG sensor H/W module with the 8-bits microprocessor is implemented. The ECG waveform can be inspected anytime with PDA in real time, and transmitted to the PC through wireless LAN. Portable ECG system can offer the environment that give the lasting medical service to the elderly and the long-time hospitalized patients at the wanted place, and the system can be attached to the chair, wheel chair, treadmill, elderly walker and used to monitor the health condition of man

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2006년도 하계종합학술대회
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• pp.391-392
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• 2006

In x-ray imaging system, twokinds of noises are involved. First, the charge generated from the radiation interaction with the detector during exposure is modeled by Poisson process. Second, the signal is then added by readout electronics noise, which is modeled by Gaussian distribution. In this paper, we applied Wiener filter and Wavelet to remove noise from medical X-ray image, the result shows that wavelet yield better segmentation results than the wiener filter.