• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.899-901
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• 2009

The magnesium fluoride ($MgF_2$) has very higher optical transmission than oxide or nitride material applied for gas barrier, so we manufactured Mg-Zn-F films with Mg-Zn-F target mixed in the various ratio of $MgF_2$ to Zn and characterized films' properties. Zn is used to increase packing density of barrier film. Thickness and optical transmission of Mg-Zn-F are 200 nm and over 90 %, respectively. The result of water vapor transmission rate at 38, RH 90 ~ 100% of the Mg-Zn-F film deposited with 4 : 6 ($MgF_2$ : Zn) ratio target reached below $1{\times}10^{-3}g$/($m^2{\cdot}day$), measuring limit of instrument.

• Journal of Sensor Science and Technology
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• v.6 no.4
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• pp.274-279
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• 1997

NOx sensors using tungsten oxide films as a base material were prepared and their electrical and sensing characteristics have been investigated. The $WO_{3}$ thick films doped with $SnO_{2}$ or $TiO_{2}$ showed higher sensitivity and better sorption characteristics to NOx gas than the pure $WO_{3}$ films material in air at operating temperature of $400^{\circ}C$. By addition of noble catalysts, such as Ru or Au, to the $TiO_{2}-WO_{3}$ thick films, their sensitivity, recovery and selectivity to NOx gas were found to be more enhanced.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.31 no.1
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• pp.29-33
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• 2018

Using a vanadium dioxide ($VO_2$) source, highly pure and amorphous vanadium oxide (VO) thin films were deposited using an e-beam evaporator at room temperature and high vacuum (<$10^{-7}$ Torr). Then, by controlling the post-annealing conditions such as $N_2:O_2$ pressure ratio and annealing time, we could easily synthesize a homogeneous $VO_2$ thin film and also mixed-phase VO thin films, including $VO_2$, $V_2O_5$, $V_3O_7$, $V_5O_9$, and $V_6O_{13}$. The crystallinity and phase of these were characterized by X-ray diffraction, and the surface morphology by FE-SEM. Moreover, the electrical properties and ethanol sensing measurements of the VO thin films were analyzed as a function of temperature. In general, mixed-phases as a self-doping effect have enhanced electrical properties, with a high carrier density and an enhanced response to ethanol. In summary, we developed an easy, scalable, and reproducible fabrication process for VO thin films that is a promising candidate for many potential electrical and optical applications.

• Journal of the Korean Institute of Telematics and Electronics T
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• v.36T no.1
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• pp.19-24
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• 1999

$In_2O_3$-based thick films for the ozone detection of ppb range have been investigated. The $In_2O_3$ sensing layer is quite sensitive to ozone, but the saturated stable sensitivity cannot be obtained at the ozone exposure of 100 ppb for 5 min. The addition of $Fe_2O_3$ into $In_2O_3$ indicates some improvement in response time and sensitivity, but it seems the improvement is not good enough for real applications. Firing of $In_2O_3$:$Fe_2O_3$ powder induces remarkable improvement in response and recovery, although the sensitivity decrease. The sensing layer fired at $1300^{\circ}C$ and operated $550^{\circ}C$ shows excellent properties of fast response time, saturated stable sensitivity and rapid recovery characteristics to 100 ppb ozone exposure for 5 min. Especially, it shows the reproducibility of the sensor signal for repeated measurements and the linearity between the ozone concentration and the sensor resistance. The preliminary results clearly demonstrated that the sensor can be successfully applied for the ozone detection of ppb range.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2079-2081
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• 2003

현재 산업화 사회가 가속됨에 따라 인체에 유해한 물질들이 발생한다. 그 중에서 VOC(Volatile Organic Component)는 인체에 치명적인 해를 일으키는 물질이다. 본 논문은 MOS(Metal Oxide Semiconductor) 센서를 이용하여 인체에 치명적인 유해 물질인 VOC를 측정하였다. 현재 VOC의 측정은 GC(Gas Chromatograph)를 이용하는데 이는 측정 시간이 길며 숙련된 측정자에 의해서만 측정이 가능하고 그 분석이 가능하다. 그러나 MOS 센서를 이용하면 숙련되지 않은 측정자도 측정이 가능하며 인공신경망을 이용하여 그 분석을 함으로서 누구나 쉽게 분석이 가능하고 실시간으로 측정이 가능하다.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.595-597
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• 2008

Zinc Oxide(ZnO) thin films on Si (100) substrate were deposited by RF magnetron sputter with changing sputtering conditions such as argon/oxygen gas ratios, RF power, and substrate temperature, chamber pressure and target-substrate distance. To analyze a crystallographic properties of the films, ${\Theta}/2{\Theta}$ mode X-ray diffraction, SEM analyses. C-axis preferred orientation highly depended on RF power.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.359-362
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• 2012

We have employed Kelvin force microscopy (KFM) system to measure the potential change of a single SnO2 nanowire which had been synthesized on the Au thin film by a thermal process. By using the KFM probing technique, Rh coated conducting cantilever can approach a single SnO2 nanowire in nano scale and get the potential images with oscillating AC bias between Au electrode and cantilever. Also, during imaging the potential status, we controlled the concentration of oxygen in measuring chamber to change the ionosorption rate. From the results of such experiments, we verified that the surface potential as well as doping type of a single SnO2 nanowire could be changed by oxygen ionosorption.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.281-281
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• 2008

최근 높은 비표면적, 우수한 결정성, 나노스케일의 크기 등 다양한 물리 화학적 특성을 지닌 1차원 나노구조체를 이용한 가스센서 연구가 활발히 진행되고 있다. 가스센서는 네트워크 된 나노선들 이용하여 벌크, 박막 보다 극대화된 비표면적으로 가스 감도와 반응 속도를 향상시킬 수 있었다. 촉매 첨가를 위해 Acetylacetone 용액 7 ml에 10 mM이 되도록 Pt 분말을 첨가하여 촉매용액을 제조하였다. 마이크로피펫을 이용하여 미량을 센서의 감응체 부문에 뿌려 대기 중에서 건조한 후 센서의 감도를 측정하였다. 측정은 $250^{\circ}C$에서 일산화탄소 가스 500 ppm의 가스농도로 촉정하였을 때 촉매가 첨가된 센서가 70% 이상의 개선된 감도를 나타내었다. 이는 나노선에 분산된 촉매에 주입되는 가스가 흡착되고 다시 표면의 산소와 반응하여 전기전도도를 변화시키는 것으로 보인다. 첨가된 촉매에 대한 영향을 분석하기 위해 AES, XRD, FT-IR, TEM 등의 분석을 실시하였다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.8 s.350
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• pp.13-18
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• 2006

[ $SnO_2$ ] and ZnO nanostructures were grown on the surface of thin film by heat treatment of metal Sn, Zn under Ar gas flow and $O_2$ at atmospheric pressure, respectively. The sensitivity of the $SnO_2$ thin film device on which grown nanowires to CO gas(5,000 ppm) was 50 % at the operating temperature of $200^{\circ}C$. In case of using Pt as catalysts, the sensitivity was enhanced and operating temperature was reduced(73 % at $150^{\circ}C$ ). The sensitivity of the ZnO nanorods device using Cu as catalysts to NOx gas was 90 % at the operating temperature of $200^{\circ}C$. It was found that the sensitivity to CO and NOx gases for the device on which grown nanostructures was much higher than those for general thin film device.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.3
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• pp.483-490
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• 2019

Assessing the effect of forest fires and measuring the gas concentration around a fire has received little attention. Therefore, the concentrations of various gases in areas surrounding a fire need to be measured by the development of a suitable device. Unlike conventional portable devices, the AQS (Air Quality System) proposed in this paper is a portable instrument that measures five types of gases simultaneously, including CO, CO2, NOx, VOCs, and NH3, and has high durability through sensor protection algorithms. A PC-based program with an AQS connection was developed to monitor the real-time changes in the gas concentration. The reliability of the developed device was proven through a comparison of the results with other commercial gas analyzers. Measurements of the concentration due to indoor and outdoor fires were performed around a fire area to review the applicability and the predicted results were obtained.