• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.04a
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• pp.135-135
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• 2006

• Proceedings of the Korean Ceranic Society Conference
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• 2002.10a
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• pp.41.1-41
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• 2002

• Journal of IKEEE
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• v.13 no.4
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• pp.37-42
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• 2009

In this study, nanopower ZnO and $SnO_2$ as sensing materials were prepared by hydrazine and hydrothermal routes, respectively, and were doped with Pd, Ru catalyst. The CO and $NO_2$ sensors were fabricated by coating of sensing materials on the MEMS-based structure with electrodes and heaters. The 0.1 wt% Pd doped $SnO_2$ sensor and Ru doped ZnO sensor showed the high sensor response to CO 30 ppm and $NO_2$ 1 ppm, respectively. The sensor signal was stable. This can be used for the detection of pollutant gases emitted from gasoline engine.

• Journal of the Korean Ceramic Society
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• v.33 no.4
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• pp.379-384
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• 1996

The H2S sensing mechanism of CuO-SnO2 was confirmed by analyzing the electrical-resistance variation with temperature under an H2S atmosphere. While the resistance of CuO-SnO2 thick film at N2+H2S atmosphere was almost invariant with change in temperature it increased with increasing temperature for air +H2S atmos-phere. This behavior was analyzed using an equation derived from a basic assumption based on the H2S sensing mechanism proposed before. the experimental results are sufficiently explained with the equation derived which showed that the H2S sensing mechanism was reasonable. The equation also gave a detailed analysis and physical meaning to the behavior of the resistance variation with change in H2S concentration.

• Proceedings of the KIEE Conference
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• 1991.11a
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• pp.245-248
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• 1991

Recently, oxide semiconductor gas sensors consisted of n-type semiconductor materials such as $SnO_2$, ZnO and $Fe_2O_3$ have been widely used to detect reducing gases. In this paper, we made the thick-film ZnO gas sensors with $PdCl_2$ as a catalyst and investigated the sensitivity to CO gas. In the thick-film Zno sensor, the highest sensitivity was shown in the sensor with 1wt.% of $PdCl_2$ which was sintered for 1 hour at $700^{\circ}C$ and operated at $300^{\circ}C$.

• Journal of Sensor Science and Technology
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• v.23 no.1
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• pp.15-18
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• 2014

We present gas sensing performance based on $2{\times}2$ sensor array with four different elements ($TiO_2$, $SnO_2$, $WO_3$ and $In_2O_3$ thin films) fabricated by rf sputter. Each thin film was deposited onto the selected $SiO_2$/Si substrate with Pt interdigitated electrodes (IDEs) of $5{\mu}m$ spacing which were fabricated on a $SiO_2$/Si substrate using photolithography and dry etching. For 5 ppm $NO_2$ and 50 ppm CO, each thin film sensor has a different response to offers the distinguishable response pattern for different gas molecules. Compared with the conventional micro-fabrication technology, $2{\times}2$ sensor array with such remarkable response pattern will be open a new foundation for monolithic integration of high-performance chemoresistive sensors with simplicity in fabrication, low cost, high reliablity, and multifunctional smart sensors for environmental monitoring.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.2
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• pp.315-322
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• 2002

A thin film oxide semiconductor micro gas sensor array which shows only 60㎽ of power consumption at an operating temperature of 30$0^{\circ}C$ has been fabricated using microfabrication and rnicrornachining techniques. Excellent thermal insulation of the membrane is achieved by the use of a double la! or structure of 0.1${\mu}{\textrm}{m}$ thick Si$_3$N$_4$ and 1${\mu}{\textrm}{m}$ thick phosphosilicate glass(PSG) prepared by low pressure chemical vapor deposition(LPCVD) and atmospheric－pressure chemical-vapor deposition(APCVD), respectively. The sensor way consists of such thin film oxide semiconductor sensing materials as 1wt.％ Pd-doped SnO$_2$, 6wt.% AI$_2$O$_3$-doped ZnO, WO$_3$ and ZnO. The thin film oxide semiconductor micro gas sensor array exhibited resistance changes usable for subsequent data processing upon exposure to various gases and the sensitivity strongly depended on the sensing layer materials. Heater Part of the sensor structure has been modified in order to improve the process yield of the sensor, and as a result of modified heater structure improved process yield has been achieved.

• 한국가스학회:학술대회논문집
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• 2007.04a
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• pp.123-126
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• 2007

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.3
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• pp.228-233
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• 2007

Core technologies for integrating hydrogen gas sensor were investigated. In this study, the thermally isolated micro-hot-plate with areas of $100{\times}100-260{\times}260{\mu}m^2$ was fabricated by utilizing surface micromachining technique that provides better manufacturing yield than bulk micromachining counterpart. The optimum design of the sensor was peformed by analyzing the thermal profile of the structure obtained from a ANSYS simulator. The 400-nm-thick polysilicon films doped with phosphorus, the 300-nm-thick aluminum films, and the 200-nm-thick $SnO_2$(or ZnO)films were used as the micro-heater material, the temperature sensor material, and the gas sensitive material, respectively. The experimental results show that the developed gas sensors can detect $H_2$ concentration as low as 1 ppm.

• Journal of Sensor Science and Technology
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• v.27 no.5
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• pp.345-351
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• 2018

We employed an unprecedented technique to synthesize porous $WO_3@SnO_2$ nanofibers exhibiting core-shell and fiber-in-tube configurations. Firstly, 2-methylimidazole was uniformly incorporated in as-spun nanofibers containing ammonium metatungstate hydrate and the sacrificial polymer (polyacrylonitrile). Secondly, the 2-methylimidazole on the surfaces of nanofibers was complexed with tin(II) chloride ($SnCl_2$) via simple impregnation of the as-spun nanofibers in ethanol containing tin(II) chloride dihydrate ($SnCl_2{\cdot}2H_2O$). The presence of vacant p-orbitals in tin (Sn) and the nucleophilic nitrogen on the imidazole ring allowed for the reaction between $SnCl_2$ and 2-methylimidazole, forming adducts on the surfaces of the as-spun nanofibers. The calcination of these nanofibers resulted in porous $WO_3@SnO_2$ nanofibers with a higher surface area ($55.3m^2{\cdot}g^{-1}$) and a better response to 1-5 ppm of acetone than pristine $SnO_2$ NFs synthesized using a similar method. An improved response to acetone was achieved upon functionalization of the $WO_3@SnO_2$ nanofibers with catalytic palladium nanoparticles. This work demonstrates the potential application of $WO_3@SnO_2$ nanofibers as sensing layers for chemiresistive sensory devices for the detection of acetone in exhaled breath.