• 센서학회지
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• 제32권2호
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• pp.105-109
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• 2023

In this study, we present a power-efficient driving method for gas sensor systems based on the analysis of input signal characteristics. The analysis of the gas sensor output signal characteristics in the frequency domain shows that most of the signal portions are distributed in a relatively low frequency region when extracting the gas sensor signal, which can lead to further performance improvement of the gas sensor system. Therefore, the proposed gas signal extracting technique changes the operating frequency of the read-out circuit based on the frequency characteristics of the output signal of the gas sensor, resulting in a reduction of power consumption at the whole system level. The proposed sensing technique, which can be applied to a general-purpose commercial gas sensor system, was implemented in a printed circuit board (PCB) to verify its effectiveness at the commercial level.

• 전기학회논문지
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• 제62권3호
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• pp.395-400
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• 2013

In this paper, we introduce the implementation of high accurate level sensor system using the pulse wave type magnetostriction sensor. When a current pulse flows along the waveguide, the magnetic field also propagates towards the end of waveguide. When this magnetic field just passes the position of the magnet for level detection, the resultant magnetic field by these two magnetic fields makes a torsional reflected signal. This is used to calculate the time difference between a interrogation pulse wave and this torsional reflected signal. The key elements and characteristics were investigated to implement level sensor system based on this principle. We introduce a method to calculate the speed of ultrasonic reflected signal and how to make a model of sensing coil. In particular, we experiment with the characteristics of the torsional reflected signal according to the changes of the interrogation voltage and displacement. To make high accurate level sensor system, two methods were compared. One is to use the comparator and time counter, the other is STFT(Short Time FFT) which is capable of the time-frequency analysis.

• 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.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.471-474
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• 2002

A fuel tank contains water at the bottom under the fuel. The water comes from humidity by temperature change of inside and outside of tank. So it is necessary to measure both level to check precise amount of oil. But measuring instrument for level of water and fuel is not available yet. Since the fuel is inflammable, the sensor system must not include any electric circuits in the fuel tank. Optical cable sensor can satisfy this non-explosive condition. The displacement of a float changing by water level makes bending curvature of optical cable different. As the float rise up, the optical cable is bent more and the light signal in the cable decreases. The reduction of light signal is detected and it is converted into the change of water level. The output signal from a photo diode shows the proportional relation of water level. The increase of sensor voltage as a unit of ㎷ follows the level position of the float that is located between water and gasoline in the tank.

• 정보보호학회논문지
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• 제31권3호
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• pp.411-422
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• 2021

무인이동체에 탑재되는 자율주행 시스템은 여러 센서를 통해 외부 환경을 인식하고 이를 통해 최적의 제어값을 도출한다. 무인이동체의 자율주행 시스템은 최근들어 사이버공격의 타겟이 되고 있다. 예를 들어, 무인이동체의 센서를 대상으로 신호오류 주입공격을 수행함으로써 센서 데이터를 악의적으로 조작하는 PHY 레벨 (Physical level) 공격과 관련한 연구 결과들이 발표되고 있다. PHY 레벨에서 수행되는 신호오류 주입공격은 주변 환경에 물리적 조작을 가하여 센서가 잘못된 데이터를 측정하게 하므로 소프트웨어 레벨에서 공격을 탐지하기 어렵다는 특징을 갖고 있다. 신호오류 주입공격을 탐지하기 위해서는 센서가 측정하는 데이터의 신뢰성을 검증하는 과정이 필요하다. 현재까지 자율주행 시스템에 탑재되는 센서들을 대상으로 PHY 레벨 공격을 시도하는 다양한 방법이 제시되었으나 이를 탐지하고 방어하는 연구는 아직까지는 부족한 상황이다. 본 논문에서는 무인이동체 환경에서 널리 쓰이고 있는 MEMS 방식의 센서를 대상으로 신호오류 주입공격을 재연하고, 이러한 공격을 탐지하는 방법을 제안한다. 제안하는 방법의 정확도를 분석하기 위해서 신호오류 주입 탐지 모델을 구축하였으며, 실험실 환경에서 유효성을 검증하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.37-38
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• 1988

In the continuous casting process, mold level sensor control system is very important for the quality of slab & bloom, in this paper, the principle of eddy current molr level sensor was studied and a method of mold oscillation signal detecting was purposed.

• 제어로봇시스템학회논문지
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• 제17권2호
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• pp.149-156
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• 2011

This paper reveals a distance estimation algorithm based on multi-code ultrasonic and wireless sensor network. For measuring the distances among the sensor nodes, each ultrasonic transmitter transmits multi-code ultrasonic signal simultaneously. Receivers use cross correlation method to separate the coded signals. The information of measured distances is broadcasted to each sensor node by wireless sensor network. The wireless sensor network measures the distance among the sensor nodes using the received signal strength of the broadcasting. The multi-code ultrasonic have a limitation of measurable distance. And the received signal strength is affected from an environment. This paper measures a distance using ultrasonic and a received signal strength in short range. These measured data are applied to the least square estimation algorithm. By the expansion of the fitting curve, a distance measurement in long range using the received signal strength is compensated. The coupled system reduce the error to an acceptable level.

• 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.

• 한국초전도ㆍ저온공학회논문지
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• 제24권1호
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• pp.29-33
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• 2022

Recently, development of a cryogenic fluids storage tank for storing or transporting liquid hydrogen is actively in progress. In cryogenic fluids storage tanks, hydrogen evaporates due to the extreme temperature difference inside and outside the tank. As the mass of the cryogenic fluids changes with continuous vaporization, the fluids level also changes. Therefore, there is need for a method of accurately measuring the level change in the storage tank. In the case of general cryogenic fluids, it is difficult to accurately measure the level because the dielectric constant is very low. As a method of measuring cryogenic fluids level with low dielectric constant, it can be used an Millimeter wave (MM wave) FMCW radar sensor. However, the signal sensitivity is very weak and the level accuracy is poor. In this paper, the signal sensitivity is improved by designing the horn lens antenna of the existing 80 GHz FMCW radar sensor. Horn lens antenna is fabricated by FDM/SLA type 3D printer according to horn and lens characteristics. The horn is used to increase the signal gain and the lens improves the signal straightness. This makes it possible to measure the level of cryogenic fluids with a low dielectric constant.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2002년도 ICCAS
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• pp.95.1-95
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• 2002

<1. New level meter inside the fuel tank> Ultrasound level sensors are widely applied as level meters of liquid tank. Measurement instrument of level between water and fuel is developed. Since the fuel is inflammable, the sensor system doesn't allow to include any electric circuit inside the fuel tank. The optical cable sensor can satisfy this explosive condition. The measurement method with ultrasonic sensor is attached on the tank wall or tank manhole lid. The pressure sensor can't be applied inside the gasoline fuel tank. An ultra-sonic sensor doesn't detect a enough signal reflected from water level deep under gasoline fuel. The pressure sensor is difficult to measure the height o...