• Journal of Sensor Science and Technology
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• v.32 no.2
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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.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.3
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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.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.1
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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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.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.31 no.3
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• pp.411-422
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• 2021

The autonomous driving system mounted on the unmanned vehicle recognizes the external environment through several sensors and derives the optimum control value through it. Recently, studies on physical level attacks that maliciously manipulate sensor data by performing signal-injection attacks have been published. signal-injection attacks are performed at the physical level and are difficult to detect at the software level because the sensor measures erroneous data by applying physical manipulations to the surrounding environment. In order to detect a signal-injection attack, it is necessary to verify the dependability of the data measured by the sensor. As so far, various methods have been proposed to attempt physical level attacks against sensors mounted on autonomous driving systems. However, it is still insufficient that methods for defending and detecting the physical level attacks. In this paper, we demonstrate signal-injection attacks targeting MEMS sensors that are widely used in unmanned vehicles, and propose a method to detect the attack. We present a signal-injection detection model to analyze the accuracy of the proposed method, and verify its effectiveness in a laboratory environment.

• Proceedings of the KIEE Conference
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• 1988.07a
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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.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.2
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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.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.3
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• pp.349-356
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• 2015

Remote monitoring partial discharge sensor, equipping with hybrid filter combining optical and electrical noise reduction capabilities and with signal integrating function to calculate total arc energy, was investigated. Hybrid filter showed insensitivity to fluorescent and incandescent lamps under simulated distribution panel condition. Signal integrating function showed selective detection capability corresponding to different arc energy levels, while convention arc sensor had difficulty to discriminate arc energy level due to bursty arc waveform and peak level detection characteristics. The sensor showed possibility for application to remote monitoring partial discharge sensor, since it detected arc energy level corresponding to normal open and close discharge in low voltage 100A MCCB at 2m distance.

• Progress in Superconductivity and Cryogenics
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• v.24 no.1
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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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• 2002.10a
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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...