• Journal of Sensor Science and Technology
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• 제22권4호
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• pp.302-307
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• 2013

The Sb-doped $SnO_2$ nanowire network sensors were prepared by thermal evaporation of the mixtures between tin and antimony powders. Pure $SnO_2$ nanowire networks showed high sensor resistance in air ($99M{\Omega}$), similar gas responses to 4 diffferent gases (5 ppm $C_2H_5OH$, CO, $H_2$, and trimethylamine), and very sluggish recovery speed (90% recovery time > 800 s). In contrast, 2 wt% Sb-doped $SnO_2$ showed the selective detection toward $C_2H_5OH$ and trimethylamine, relatively low resistance ($176k{\Omega}$) for facile measurement, and ultrafast recovery speed (90% recovery times: 6 - 18 s). The change of gas sensing charactersitics by Sb doping was discussed in relation to gas sensing mechanism.

• Journal of Sensor Science and Technology
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• 제33권5호
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• pp.242-247
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• 2024

Pure and 0.3 wt% Au-doped In₂O₃ hollow spheres were synthesized via ultrasonic spray pyrolysis of droplets containing an In-source and sucrose in air and their gas sensing characteristics to 1 ppm ethanol, 1 ppm toluene, 1 ppm xylene, 2 ppm nitrogen dioxide (NO₂), and 30 ppm carbon monoxide (CO) were measured at 400 - 450℃. The pure In₂O₃ hollow spheres exhibited relatively low gas responses and sluggish recovery kinetics. In contrast, the doping of Au into In₂O₃ hollow spheres significantly increased the gas response (S= resistance ratio) to 1 ppm ethanol (S= 20.6) at 400℃ with low cross-responses (S = 1.3-8.8) to other interference gases. Furthermore, the hollow spherical morphology of In₂O₃ provides a large surface area and facilitates rapid gas diffusion, resulting in fast response and recovery times. The sensor exhibited excellent performance with a low detection limit of 1.6 ppb. These findings indicate that the Au-In₂O₃ hollow spheres are promising candidates for advanced ethanol-sensing applications, particularly in breath-alcohol monitoring for ignition interlock devices.

• Transactions on Electrical and Electronic Materials
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• 제16권6호
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• pp.334-337
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• 2015

Pure ZnO, ZnO nanowires doped with 3 wt.% Ga (3GZO) and doped with 3 wt.% Ag (3SZO) were grown by a hot-walled pulse laser deposition (HW-PLD) technique. The optical and chemical properties of Ga and Ag doped nanowires was analyzed. Nanowires were determined to be under 200 nm in diameter and several μm in length. Change of significant resistance was observed and the gas detection sensitivities of ZnO, 3GZO and 3SZO nanawires were compared. The sensitivities of ZnO, 3GZO, and 3SZO nanowire sensors were measured at 300℃ for 1 ppm of ethanol gas at 97%, 48%, and 203%, respectively.

• Korean Journal of Pharmacognosy
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• 제20권4호
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• pp.205-214
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• 1989

The sensing of odour compounds in gas phase is an attractive target in recent sensor technology. Based on the finding that a plant leaf can respond to various gas molecules by changing its potential, biosensing system using a plant leaf has been investigated for the detection of odour compounds. A leaf of some plant species responded to odour compounds directly by changing its potential $5{\sim}10\;mV$. That the leaf was actually sensing an odour was much more remarkably detected from the difference between the response profile to pure $CO_2$ gas and that to $CO_2$ gas containing odour compounds. Then the quantitative study (ppb level) is now being performed on the response of a tobacco leaf to benzyl acetate; a component of jasminelike odours. The concept of biosensing and its significance are also described from the viewpoint of sensor technology.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1995년도 추계학술대회 논문집
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• pp.187-189
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• 1995

A Surface Acoustic Wave Gas sensor for NO, CO, H$_2$gas detection was designed fabricated, and tested. A delay line device was designed to composite a single mode SAW oscillator which enables to measure a SAW velocity. To reduce the effect of temperature and humidity, dual delay line oscillator circuit was used. And final output was measured by digital frequency counter. NO, CO, H$_2$gas were detected by WO$_3$thin film deposited on the path of the Delay Line.

• Journal of the Korean Ceramic Society
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• 제34권4호
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• pp.387-393
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• 1997

In order to apply WO3 thin films to the semiconducting NOx gas sensors as a sensing material, which have been expected to show good electrical properties, such as large sensitivity, rapid responsibility, and high selectivity, the fabrication method and their sensing characteristics were studied. The variations of surface morphologies, crystallographic orientations and crystallinity with the WO3 thin film growing methods thermal evaporation and DC sputtering methods were investigated by using scanning electron microscopy (SEM) and X-ray diffraction(XRD) analysis. As a result of sensitivity (Rgas/Rair) measurements for the 5 ppm NO2 test gas, the sensitivity values were 113 for the sputtered films and 93 for the evaporated films. It was also observed that the recovery rate of a sensing signal after measuring sensitivity was faster in the sputtered films than in the evaporated films.

• Journal of the Korean Society of Industry Convergence
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• 제19권2호
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• pp.95-100
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• 2016

This study proposes the temperature compensation algorithm using thermopile detector for non-dispersive infrared Nitrogen gas sensor. From the output voltage of thermistor that is attached onto the infrared detector, the ambient temperature was extracted. The effects of temperatures on the properties of sensor module characteristics of narrow bandpass filter, optical cavity and infrared lamp, and air mixing gas have been introduced in order to implement the temperature compensation algorithm.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제26권9호
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• pp.707-711
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• 2013

Carbon nanotubes(CNT) has strength and chemical stability, greatly conductivity characteristics. In particular, MWCNT (multi-walled carbon nanotubes) show rapidly resistance sensitive for changes in the ambient gas, and therefore they are ideal materials to gas sensor. So, we fabricated NOx gas sensors structured MOS-FET using MWCNT (multi-walled carbon nanotubes) material. We investigate the change resistance of NOx gas sensors based on MOS-FET with ultra lean NOx gas concentrations absorption. And NOx gas sensors show sensitivity on the change of gate-source voltage ($V_{gs}=0[V]$ or $V_{gs}=3.5[V]$). The gas sensors show the increase of sensitivity with increasing the temperature (largest value at $40^{\circ}C$). On the other hand, the sensitivity of sensors decreased with increasing of NOx gas concentration. In addition, We obtained the adsorption energy($U_a$), $U_a$ = 0.06714[eV] at the NOx gas concentration of 8[ppm], $U_a$ = 0.06769[eV] at 16[ppm], $U_a$ = 0.06847[eV] at 24[ppm] and $U_a$ = 0.06842[eV] at 32[ppm], of NOx gas molecules concentration on the MWCNT gas sensors surface with using the Arrhenius plots. As a result, the saturation phenomena is occurred by NOx gas injection of concentration for 32[ppm].

• Journal of Sensor Science and Technology
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• 제32권3호
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• pp.180-186
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• 2023

Test devices can perform various functions, such as research on detection targets, sensors that detect detection targets, combined products containing sensors, and certification for the launch of combined products. However, the scope of use of test devices is limited because they perform only a single role or could only serve a particular purpose in the past. Therefore, studies on test devices that can perform various functions, such as research on detection targets, sensors that detect detection targets, combined products containing sensors, and certification for the release of combined products are necessary. Accordingly, this study proposes a test device that can increase the scope of use in the technical field of electric fires. In addition, we examine various outcomes of the proposed test device.

• Journal of the Korea Safety Management & Science
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• 제17권4호
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• pp.297-304
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• 2015

This study concerns the integrated gas sensor system of wire and wireless communication by using IoT(Internet of Things) technology. First, communication part is that it delivers the detection information, which transferred by wire or wireless communication and required control procedure based on a wireless module that receives the gas leakage information from wired or wireless detector, to administrator or user's terminal. Second, receiver part is that it shows the location and information, which received from the wired detector formed by a detecting sensor's node as linking with the communication part, and transfers these to the communication part. Third, wireless detector formed as a communication module of a detecting sensor node is that it detects gas leakage and transfers the information through wireless as a packet.Fourth, wired detector communicated with the receiver part and formed as a communication module of a detecting sensor node is that it detects gas leakage, transfers and shows the information as a packet. Fifth, administrator's terminal is that it receives gas leakage information by the communication part, transfers the signal by remote-control, and shut off a gas valve as responding the information. Sixth, database is that it is connected with the communication part; it sets and stores the default values for detecting smoke, CO., and temperature; it transfers this information to the communication part or sends a gas detecting signal to user's terminal. Seventh, user's terminal is that it receives each location's default value which stored and set at the database; it manages emergency situation as shutting off a gas valve through remote control by corresponding each location's gas leakage information, which transferred from the detector to the communication part by wireless.It is possible to process a high quality data regarding flammable or toxic gas by transferring the data, which measured by a sensor module of detector, to the communication part through wire and wireless. And, it allows a user to find the location by a smart phone where gas leaks. Eventually, it minimizes human life or property loss by having stability on gas leakage as well as corresponding each location's information quickly.