• New & Renewable Energy
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• v.7 no.3
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• pp.67-73
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• 2011

MGT fuelled by landfill gas was tested to asses feasibility of its exhaust gas application for $CO_2$ enrichment. The exhaust gas was analyzed during start-up and normal operation with different MGT load conditions. Due to the changes of air/fuel ratio and combustion mode, $O_2$, $CO_2$, CO and NOx concentration were varied within wide ranges during the MGT start-up. Especially, NOx emissioin level was increased up to 20.01 ppmv. Different tendencies of $O_2$, $CO_2$, CO and NOx concentrations were observed with MGT output changes. $O_2$ and CO concentrations were shown to be decreased and NOx and $CO_2$ concentrations were shown to have opposite trends. NOx emission level (0.8~1.88 ppmv) was very low compared to other types of combustion based power generation equipment. Unburned hydrocarbon emission level was substantially decreased with MGT load increase. Especially, $C_2H_4$ concentration was below the detection limit(0.2 ppmv) around the nominal load condition. The exhaust gas from landfill gas fuelled MGT system was shown to be feasible for $CO_2$ fertilization. Concentrations of major components were within or below the maximum allowable ranges.

• Journal of the Korean Institute of Gas
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• v.15 no.4
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• pp.27-32
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• 2011

Management of gas safety is becoming important with increasing use of gas facilities. U-safety system is being promoted as part of national management of gas, and thus real-time and in-situ gas sensor should be developed. Detection method for When the gas sensor is installed in gas conduit, explosion may be likely, because hydrocarbon gases is usually used the difference of thermal resistance between reference and working electrode. Therefore, it is required to detect the hydrocarbons, such as $CH_4$ and CO, at room temperature via electrochemically catalytic reaction. In this study, Pt nanoparticle was doped on the porous gold powder by electrolytic plating method, and then it was used as catalytic electrode for CO oxidation. For Pt/PAu electrode, approximately 21% of CO conversion was obtained. It is noted that Pt/PAu electrode could be used to react the oxidation of hydrocarbon gases at room temperature via applying of external voltage.

• Korean Journal of Materials Research
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• v.20 no.5
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• pp.235-240
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• 2010

We investigated the carbon monoxide (CO) gas-sensing properties of nanostructured Al-doped zinc oxide thin films deposited on self-assembled Au nanodots (ZnO/Au thin films). The Al-doped ZnO thin film was deposited onto the structure by rf sputtering, resulting in a gas-sensing element comprising a ZnO-based active layer with an embedded Pt/Ti electrode covered by the self-assembled Au nanodots. Prior to the growth of the active ZnO layer, the Au nanodots were formed via annealing a thin Au layer with a thickness of 2 nm at a moderate temperature of $500^{\circ}C$. It was found that the ZnO/Au nanostructured thin film gas sensors showed a high maximum sensitivity to CO gas at $250^{\circ}C$ and a low CO detection limit of 5 ppm in dry air. Furthermore, the ZnO/Au thin film CO gas sensors exhibited fast response and recovery behaviors. The observed excellent CO gas-sensing properties of the nanostructured ZnO/Au thin films can be ascribed to the Au nanodots, acting as both a nucleation layer for the formation of the ZnO nanostructure and a catalyst in the CO surface reaction. These results suggest that the ZnO thin films deposited on self-assembled Au nanodots are promising for practical high-performance CO gas sensors.

• Korean Journal of Materials Research
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• v.21 no.10
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• pp.546-549
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• 2011

Nano-sized $SnO_2$ thick films were prepared by a screen-printing method onto $Al_2O_3$ substrates. The sensing characteristics were investigated by measuring the electrical resistance of each sensor in a test box as a function of the detection gas. The nano-sized $SnO_2$ thick film sensors were treated in a $N_2$ atmosphere. The structural properties of the nano $SnO_2$with a rutile structure according to XRD showed a (110) dominant $SnO_2$ peak. The particle size of $SnO_2$:Ni nano powders at Ni 8 wt% was about 45 nm, and the $SnO_2$ particles were found to contain many pores according to the SEM analysis. The sensitivity of the nano $SnO_2$-based sensors was measured for 5 ppm $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature by comparing the resistance in air with that in the target gases. The results showed that the best sensitivity of $SnO_2$:Ni and $SnO_2$:Co sensors for $CH_4$ gas and $CH_3CH_2CH_3$ gas at room temperature was observed in $SnO_2$:Ni sensors doped with 8 wt% Ni. The response time of the $SnO_2$:Ni gas sensors was 10 seconds and recovery time was 15 seconds for the $CH_4$ and $CH_3CH_2CH_3$ gases.

• Korean Journal of Materials Research
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• v.24 no.3
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• pp.152-158
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• 2014

We report the effect of the fabric of the surface microstructure on the CO gas sensing properties of $SnO_2$ thin films deposited on self-assembled Au nanodots ($SnO_2$/Au) that were formed on $SiO_2/Si$ substrates. We characterized structural and morphological properties, comparing them to those of $SnO_2$ thin films deposited directly onto $SiO_2/Si$ substrates. We observed a significant enhancement of CO gas sensing properties in the $SnO_2$/Au gas sensors, specifically exhibiting a high maximum response at $200^{\circ}C$ and quite a low detection limit of 1 ppm level in dry air. In particular, the response of the $SnO_2/Au$ gas sensor was found to reach the maximum value of 32.5 at $200^{\circ}C$, which is roughly 27 times higher than the response (~1.2) of the $SnO_2$ gas sensor obtained at the same operating temperature of $200^{\circ}C$. Furthermore, the $SnO_2/Au$ gas sensors displayed very fast response and recovery behaviors. The observed enhancement in the CO gas sensing properties of the $SnO_2/Au$ sensors is mainly ascribed to the formation of a nanostructured morphology in the active $SnO_2$ layer having a high specific surface-reaction area by the insertion of a nanodot form of Au nucleation layer.

• Journal of the Korea Convergence Society
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• v.11 no.12
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• pp.23-30
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• 2020

In this study, the relationship between natural gas (NG) data and gas-related environmental elements was performed using machine learning algorithms to predict the level of gas leakage risk without directly measuring gas leakage data. The study was based on open data provided by the server using the IoT-based remote control Picarro gas sensor specification. The naturel gas leaks into the air, it is a big problem for air pollution, environment and the health. The proposed method is multivariate outlier removing method based Random Forest (RF) classification for predicting risk of NG leak. After, unsupervised k-means clustering, the experimental dataset has done imbalanced data. Therefore, we focusing our proposed models can predict medium and high risk so best. In this case, we compared the receiver operating characteristic (ROC) curve, accuracy, area under the ROC curve (AUC), and mean standard error (MSE) for each classification model. As a result of our experiments, the evaluation measurements include accuracy, area under the ROC curve (AUC), and MSE; 99.71%, 99.57%, and 0.0016 for MOL_RF respectively.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.42-48
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• 2021

In this study, a sensor for detection of nitric oxide (NO) gas was developed using petroleum pitch-based activated carbon which was synthesized from pyrolysis fuel oil (PFO). Polyethylene terephthalate (PET) was added to increase molecular weight by stimulating a polymerization of components in PFO during the pitch synthesis process. The increase in the molecular weight of pitch contributed to the improvement of textural properties of activated carbon, such as the specific surface area and micropore volume. It also enhanced the sensitivity of NO gas sensor based on the activated carbon. In addition, the effect of PET addition during the pitch synthesis on the surface oxygen content and conductivity of activated carbon was investigated. Finally, the correlation of the sensitivity with physical properties of activated carbon was analyzed.

• Journal of Photoscience
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• v.9 no.2
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• pp.409-411
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• 2002

In order to prevent side reactions due to free radical formation occurring in the reactions of singlet oxygen generated in solution phse, it was required that singlet oxygen is generated in gas phase from an apparatus of a solid-gas system. We have accomplished to construct an apparatus generating singlet oxygen in solid-gas system, which is composed of a flexible optical fibre tube connected by a dye-sensitizer probe containing rose bengal dye on polymer or inorganic material. Through the optical fibre tube visible light from a laser and an oxygen stream are passed into the sensitizer probe where singlet oxygen is generated. The determination of singlet oxygen was carried out by two methods. One involves the detection of the luminescence of singlet oxygen at 1268 mn and the other involves the chemiluminescence reaction of a dihydroisobenzofuran with singlet oxygen emitting luminescence at 456 nm.

• Proceedings of the KIEE Conference
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• 2004.07c
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• pp.1555-1557
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• 2004

The Pt-doped $SnO_2$ thin film for CO sensor applications obtained by RF sputtering from a target of the same compound in an Ar-$O_2$ atmosphere. Pt-SnO2-SiC Schottky diode detection of CO gas Cause the remarkable change in electrical resistivity of the semiconductor. the good gas sensitivity is shown when annealing condition is 600$^{\circ}C$, 1hr in RTP and detected temperature is 350$^{\circ}C$.

• Electrical & Electronic Materials
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• v.10 no.5
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• pp.419-424
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• 1997

It is well known that the metallo-phthalocyanines (MPcs) are sensitive to toxic gaseous molecules such as NO$_2$ as well as are chemically and thermally stable. Therefore, lots of MPcs have been studied as the potential chemical sensor for NO$_2$gas using quartz crystal microbalance(QCM) or electrical conductivity. In this study, thin films of octa(2-ethylhexyloxy)copper-phthalocyanine were prepared by Langmuir-Blodgett method and characterized by using UV-VIS absorption spectroscopy and ellipsometry. Optimal transfer condition of LB films was investigated and preliminary results of current-voltage(I-V) characteristics of these films exposed to NO$_2$gas as a function of film thickness, temperature and concentration were discussed.