• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2004.10a
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• pp.279-282
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• 2004

본 논문에서는 자기저항 센서를 이용하여 자율주행 시스템에서 필요로 하는 자석의 종류에 따른 자계의 특성을 분석하였다 분석결과 거리에 따라 자계의 특성이 변화하고, 자석에 근접할수록 자계의 변화가 급격하게 나타난다. 센서가 자석에서 멀어질수록 지자계의 값에 가까워진다 또한 페라이트자석 보다 네오디뮴 자석의 자계특성이 우수함을 보였다.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.6-6
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• 2000

By using the information obtained from the outputs of MR(MagnetoResistive) sensors for an Unmanned Vehicle Driving System, we develop an algorithm that decides the distance and direction between vehicle and the guideline which is made by the magnet. To improve the robust tracking properties of the closed loop system, we introduce H$\infty$ controller and its application for the Unmanned Vehicle Driving System.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2385-2387
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• 2002

종래 도로상의 차량검지기들은 기후변화 및 도로환경의 변화, 물리적인 변화에 영향을 받아 감지의 정확도가 떨어져 신뢰도 높은 교통정보를 생성하기가 어렵고, 제품의 가격이 고가이며, 설치 및 유지, 보수에 많은 비용과 인력이 요구된다. 본 연구에서는 종래의 차량 검지기가 지니는 문제점들을 해결하여 어떠한 환경하에서도 신뢰성 있는 차량 주행정보를 제공하며 동시에 유지, 보수 비용이 저렴한 검지기로서 AMR(Anisotropic Magneto-Resistive) 센서를 이용하여 도로상의 차량 이동에 따른 지구자기장(Earth Magnetic Field) 변화를 감지하고 차량의 이동상태를 파악하는 교통량 계측장치를 제시한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.12
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• pp.1089-1094
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• 2009

Carbon nanotubes (CNTs) have excellent electrical, chemical stability, mechanical and thermal properties. In this paper, networks of Multi-walled carbon nanotube (MWCNT) materials were investigated as resistive gas sensors for ethanol ($C_2H_5OH$) detection. Sensor films were fabricated by air spray method for the multi-walled CNTs solution on glass substrates. Sensors were characterized by resistance measurements in the sensing system, in order to find the optimum detection properties for the ethanol gas molecular. The film that was sprayed with the MWCNT dispersion for 60 see, was 300 nm thick. And the electric resistivity is $2{\times}10^{-2}\;{\Omega\cdot}cm$. Also, the sensitivity and the linearity of MWVNT sensor for ethanol gas are 0.389 %/sec and 17.541 %/FS, respectively. The MWCNT film was excellent in the response for the ethanol gas molecules and its reaction speed was very fast, which could be using as ethanol gas sensor. The conductance of the fabricated sensors decreases when the sensors are exposed to ethanol gas.

• Journal of Sensor Science and Technology
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• v.24 no.3
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• pp.155-158
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• 2015

In this paper, in-situ heat cooling with temperature monitoring is reported to solve thermal issues in electric vehicle (EV) batteries. The device consists of a thick graphene cooler on top of the substrate and a platinum-based resistive temperature sensor with an embedded heater above the graphene. The graphene layer is synthesized by using chemical vapor deposition directly on the Ni layer above the Si substrate. The proposed thick graphene heat cooler does not use transfer technology, which involves many process steps and does not provide a high yield. This method also reduces the mechanical damage of the graphene and uses only one photomask. Using this structure, temperature detection and cooling are conducted simultaneously using one device. The temperature coefficient of resistance (TCR) of a $1{\times}1mm^2$ temperature sensor on 1-$\grave{i}m$-thick graphene is $1.573{\times}10^3ppm/^{\circ}C$. The heat source cools down $7.3^{\circ}C$ from $54.4^{\circ}C$ to $47.1^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.290-294
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• 2023

Among various types of harmful gases, hydrogen sulfide is a strong toxic gas that is mainly generated during spillage and wastewater treatment at industrial sites. Hydrogen sulfide can irritate the conjunctiva even at low concentrations of less than 10 ppm, cause coughing, paralysis of smell and respiratory failure at a concentration of 100 ppm, and coma and permanent brain loss at concentrations above 1000 ppm. Therefore, rapid detection of hydrogen sulfide among harmful gases is extremely important for our safety, health, and comfortable living environment. Most hydrogen sulfide gas sensors that have been reported are electrical resistive metal oxide-based semiconductor gas sensors that are easy to manufacture and mass-produce and have the advantage of high sensitivity; however, they have low gas selectivity. In contrast, the electrochemical sensor measures the concentration of hydrogen sulfide using an electrochemical reaction between hydrogen sulfide, an electrode, and an electrolyte. Electrochemical sensors have various advantages, including sensitivity, selectivity, fast response time, and the ability to measure room temperature. However, most electrochemical hydrogen sulfide gas sensors depend on imports. Although domestic technologies and products exist, more research is required on their long-term stability and reliability. Therefore, this study includes the processes from electrode material synthesis to sensor fabrication and characteristic evaluation, and introduces the sensor structure design and material selection to improve the sensitivity and selectivity of the sensor. A sensor case was fabricated using a 3D printer, and an Ag reference electrode, and a Pt counter electrode were deposited and applied to a Polytetrafluoroethylene (PTFE) filter using PVD. The working electrode was also deposited on a PTFE filter using vacuum filtration, and an electrochemical hydrogen sulfide gas sensor capable of measuring concentrations as low as 0.6 ppm was developed.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.32.6-32
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• 2001

This paper describes the steering control and geomagnetism cancellation for an autonomous mobile robotusing MR sensors. The magnetic-resistive (MR) sensor obtains the vector summation of the magnetic fields from embedded magnets and the Earth. The robot is controlled by the magnetic fields from embedded magnets. So, geomagnetism is the disturbance in the steering control system. In this paper, we propose a new method of the sensor arrangement in order to remove the geomagnetism and robotbody interference. The proposed method uses two MR sensors located in a level plane and the steering controller has been developed. The controller has three input variables (dBx, dBy, dBz) using the measured magnetic field difference, and an output variable (the steering angle) ...

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1063-1066
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• 2003

A flow-meter and its measurement controller was developed for a hydraulic system. This study, for development of positive displacement flow-meter, consist of PIC(Peripheral Interface Controller) controller with MR(Magneto-resistive) sensors. This flow-meter is used valve position indicator for valve control system by hydraulic. The MR sensors are used for the rotation of OVAL gear that detecting device. In the ship environments, consideration that necessary explosive proof. Thus electro device or electro flow-meter needs explosion design for electric circuit. We designed noncontact type flow-meter and evaluated the safety and measuring abilities.

• Journal of the Korean Society of Safety
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• v.4 no.1
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• pp.71-74
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• 1989

The $\alpha$-Fe$_2$O$_3$ gas sensor, prepared by the precipitation of Fe(OH)$_3$ from a solution of iron(III) sulfate and tin (IV) chloride, was composed of fine particles and was superior in sensitivity to other $\alpha$-Fe$_2$O$_3$. The gas sensitivity was found to depend on the amounts of remaining sulfate ion the microstructure and a small amount of iron(II) species generated through the reduction of $\alpha$-Fe$_2$O$_3$. The sensing mechanism of $\alpha$-Fe$_2$O$_3$gas sensor was confirmed to be due to the reduction of $\alpha$-Fe$_2$O$_3$ to the low resistive Fe$_3$-xO$_4$ by combustible gas and to depend on the crystral structure.

• Journal of Power Electronics
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• v.12 no.6
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• pp.954-959
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• 2012

A hybrid switch that uses a microelectromechanical system (MEMS) switch as a gate driver of a MOSFET is applied to an energy harvesting system. The power management circuit adopting the hybrid switch provides ultralow leakage, self-referencing, and high current handling capability. Measurements show that solar energy harvester circuit utilizing the MEMS-MOSFET hybrid switch accumulates energy and charges a battery or drive a resistive load without any constant power supply and reference voltage. The leakage current during energy accumulation is less than 10 pA. The power management circuit adopting the proposed hybrid switch is believed to be an ideal solution to self-powered wireless sensor nodes in smart grid systems.