• 한국인터넷방송통신학회논문지
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• 제9권6호
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• pp.49-54
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• 2009

무선 센서 네트워크에서 센서 노드는 제한된 자원과 센싱 능력을 가지고 있으며 분산된 환경에서 동작한다. 특히 적은 에너지 자원을 가지고 있으며, 한 번 살포된 후에는 사용자의 접근이 제한되며 배터리를 교체할 수 없다. 에너지 소비를 최소화하여 전체 센서 네트워크의 수명을 최대화하는 것은 중요한 이슈 중 하나이다. LEACH에서는 현재 에너지 량을 고려하지 않고 확률적으로 클러스터 헤드를 선택한다. 본 논문에서는 평균 에너지 레벨보다 센서 노드의 에너지 레벨이 높을 경우, 클러스터 헤드로 선출될 자격을 부여하는 클러스터 형성 기법을 제안한다. 시뮬레이션을 통해 제안하는 클러스터 형성 기법의 우수성을 검증한다.

• Journal of Advanced Marine Engineering and Technology
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• 제37권7호
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• pp.778-783
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• 2013

Measurement of liquid level in storage and processing vessels, tanks, wells, reservoirs and hoppers is commonly needed. The several different ways to measure the liquid level of oil or water tank have been provided such as an electrostatic capacity, a supersonic waves and an optical science etc. In the study, we have constructed the stable and efficient measurement system to measure the level of liquid at real-time and to get accurate measurement of the maximum and minimum level of the tank. For this purpose, we suggest double sensing methods by adopting both capacitive and optical sensing. The experimental results, presented in this paper, illustrate the effectiveness of the proposed method under different sensing methods.

• ETRI Journal
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• 제43권3호
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• pp.511-523
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• 2021

The World Health Organization provides guidelines for managing the particulate matter (PM) level because a higher PM level represents a threat to human health. To manage the PM level, a procedure for measuring the PM value is first needed. We use a PM sensor that collects the PM level by laser-based light scattering (LLS) method because it is more cost effective than a beta attenuation monitor-based sensor or tapered element oscillating microbalance-based sensor. However, an LLS-based sensor has a higher probability of malfunctioning than the higher cost sensors. In this paper, we regard the overall malfunctioning, including strange value collection or missing collection data as anomalies, and we aim to detect anomalies for the maintenance of PM measuring sensors. We propose a novel architecture for solving the above aim that we call the hypothesis pruning generative adversarial network (HP-GAN). Through comparative experiments, we achieve AUROC and AUPRC values of 0.948 and 0.967, respectively, in the detection of anomalies in LLS-based PM measuring sensors. We conclude that our HP-GAN is a cutting-edge model for anomaly detection.

• 센서학회지
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• 제27권5호
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• pp.300-305
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• 2018

The uncooled microbolometer thermal sensor for low cost and mass volume was designed to target the new infrared market that includes smart device, automotive, energy management, and so on. The microbolometer sensor features 80x60 pixels low-resolution format and enables the use of wafer-level vacuum packaging (WLVP) technology. Read-out IC (ROIC) implements infrared signal detection and offset correction for fixed pattern noise (FPN) using an internal digital to analog convertor (DAC) value control function. A reliable WLVP thermal sensor was obtained with the design of lid wafer, the formation of Au80%wtSn20% eutectic solder, outgassing control and wafer to wafer bonding condition. The measurement of thermal conductance enables us to inspect the internal atmosphere condition of WLVP microbolometer sensor. The difference between the measurement value and design one is $3.6{\times}10-9$ [W/K] which indicates that thermal loss is mainly on account of floating legs. The mean time to failure (MTTF) of a WLVP thermal sensor is estimated to be about 10.2 years with a confidence level of 95 %. Reliability tests such as high temperature/low temperature, bump, vibration, etc. were also conducted. Devices were found to work properly after accelerated stress tests. A thermal camera with visible camera was developed. The thermal camera is available for non-contact temperature measurement providing an image that merged the thermal image and the visible image.

• 센서학회지
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• 제21권2호
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• pp.121-126
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• 2012

Piezoresistive type contact force sensor array is fabricated by (111) Silicon bulk micromachining for continuous blood pressure monitoring. Length and width of the unit sensor structure is $200{\mu}m$ and $190{\mu}m$, respectively. The gap between sensing elements is only $10{\mu}m$. To achieve wafer level packaging, the sensor structure is capped by PDMS soft cap using wafer molding and bonding process with $10{\mu}m$ alignment precision. The resistance change over contact force was measured to verify the feasibility of the proposed sensor scheme. The maximum measurement range and resolution is 900 mm Hg and 0.57 mm Hg, respectively.

• 한국인터넷방송통신학회논문지
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• 제18권4호
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• pp.143-147
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• 2018

수위는 하수장, 정수장, 하천, 댐, 공장의 저장탱크 등 다양한 분야에서 측정된다. 수위측정을 위한 초음파 기기가 판매중이나 산업용으로 실험에서 사용하기는 가격이 너무 비싸다. 전자 기술의 급속한 진보로 인해 다양한 종류의 측정, 모니터링 및 제어 기능이 저렴하게 구축하는 것이 가능해졌다. 저렴한 가격으로 초음파 수위 측정시스템을 만들기 위하여 본 연구가 시작되었다. 실험용으로 사용하기 위하여 아두이노, 초음파 센서 및 온도 센서로 시스템을 구성하였다. 초음파 센서는 센서에서 수위 표면까지의 시간을 측정한다. 온도 센서는 대기 온도를 측정하며 온도 변화로 인한 소리의 속도를 보정하여 초음파 거리 측정의 정확성을 높인다. 아두이노는 측정 전반을 관리하고 수위를 계산한다. 시스템의 모든 구성 요소는 장치거치대에 조립되었다. 제안된 시스템을 가지고 실험한 결과 수위가 실측치와 매우 가까웠다. 이 시스템은 또한 저렴하며 설치 및 유지하기가 쉬워 실험용으로 적절하다.

• 제어로봇시스템학회논문지
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• 제17권1호
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• pp.1-5
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• 2011

The basic signals for electronic engine control are velocity and degree of the engine cam shaft. The CPS sensor used for this signal and magnetic pick-up type CPS sensor is more popular. It is very important thing analyze this signal correctly. If there are some mistakes at the analysis, like a noise, The engine do not working at the best status, it will generate some noise, emit exhaust fumes and waste more gases. In general way to analysis this signal, you use zero-level detector circuit and in order to reduce the error you must use another sensor like a TDC sensor. In this paper, We proposed the analysis method using electronics circuits for magnetic pick-up type CPS sensor. We designed Comparison level detector circuit, Differential circuit and Full-rectifier circuit for detected the Long tooth and Short tooth level correctly without another sensor. We expected it is useful for more reliable engine control.

• 한국전자통신학회논문지
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• 제10권3호
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• pp.349-356
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• 2015

광학적 잡음과 전기적 잡음을 복합적으로 제거할 수 있는 하이브리드 필터를 채용하고 펄스형태의 아크 광 신호를 적분하여 수신되는 아크에너지의 크기로 감지할 수 있는 원격감시 기능을 갖는 고감도 부분방전 센서를 구현하였다. 하이브리드 필터는 부분방전 센서가 설치되는 배전반 내 환경에서 내부 형광등과 백열등 조명에 대하여 영향을 받지 않음을 보여주었다. 종래에는 아크광의 불규칙한 파형특성으로 인하여 첨두치가 감지되어 아크광의 크기에 비례한 선택적 감지가 어려웠으나, 센서에 적용된 적분연산 기능은 각기 다른 아크광의 에너지 레벨에 대하여도 선택적으로 감지가 가능함을 실험적으로 보여주었다. 센서는 2m 이격된 원격지에서 100A 저압 MCCB의 정상 개폐 시 발생하는 섬광에 해당하는 광 에너지에 대해서도 감지가 가능함을 보여주어 원격감시 기능을 갖는 고감도 부분방전센서에 적용 가능함을 보여주었다.

• 센서학회지
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• 제30권1호
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• pp.25-29
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• 2021

In this study, we successfully developed a highly reliable ultrasonic sediment sensor to detect the sediment levels in sewer pipes in harsh environments. The ultrasonic transducer employed in the ultrasonic sediment sensor was designed so as to possess a simple structure. The developed sensor was carefully optimized by simulating the electromechanical characteristics, radiated sound wave pressures, and directivity via finite element analysis. It was also designed to possess a simple mounting structure minimizing the flow disturbance in a 400-mm sewer pipe; additionally, eight ultrasonic transducers were arranged in a four-channel mode, allowing for measurement of the sediment height in five easy steps. Through experimental evaluations, we verified the performance of the ultrasonic sediment-level sensor and its industrial applicability. The results suggested that although the precision value was notably low at 15 mm, the sediment detection performance was adequate; therefore, the developed sensor can potentially be used in industrial applications.

• Nuclear Engineering and Technology
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• 제39권2호
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• pp.133-142
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• 2007

The Electric Power Research Institute (EPRI) demonstrated a method for monitoring the performance of instrument channels in Topical Report (TR) 104965, 'On-Line Monitoring of Instrument Channel Performance.' This paper presents the results of several models originally developed by EPRI to monitor three nuclear plant sensor sets: Pressurizer Level, Reactor Protection System (RPS) Loop A, and Reactor Coolant System (RCS) Loop A Steam Generator (SG) Level. The sensor sets investigated include one redundant sensor model and two non-redundant sensor models. Each model employs an Auto-Associative Kernel Regression (AAKR) model architecture to predict correct sensor behavior. Performance of each of the developed models is evaluated using four metrics: accuracy, auto-sensitivity, cross-sensitivity, and newly developed Error Uncertainty Limit Monitoring (EULM) detectability. The uncertainty estimate for each model is also calculated through two methods: analytic formulas and Monte Carlo estimation. The uncertainty estimates are verified by calculating confidence interval coverages to assure that 95% of the measured data fall within the confidence intervals. The model performance evaluation identified the Pressurizer Level model as acceptable for on-line monitoring (OLM) implementation. The other two models, RPS Loop A and RCS Loop A SG Level, highlight two common problems that occur in model development and evaluation, namely faulty data and poor signal selection