• Title/Summary/Keyword: H2S sensing

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GOES-9 GVAR Imager Processing System Development by KARI

  • Ahn, S.I.;Koo, I.H.;Yang, H.M.;Hyun, D.H.;Park, D.J.;Kang, C.H.;Kim, D.S.;Choi, H.J.;Paik, H.Y.
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.31-33
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    • 2003
  • Recently, KARI developed in-house meteorological sensor processing system named MESIS for GOES GVAR 5-CH Imager for better KOMPSAT EOC mission operation. MESIS consists of antenna system, receiver, serial telemetry card, processing and mapping software, and 2 NT PC systems. This paper shows system requirement, system design, characteristic and test results of processing system. System operation concept and sample image are also provided. Implemented system was proven to be fully operational through lots of operations covering from RF signal reception to web publishing.

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Dynamic Magneto-mechanical Behavior of an Iron-nickel-based Ferromagnetic Alloy with Constant Elasticity

  • Bian, Leixiang;Wen, Yumei;Li, Ping;Gao, Qiuling;Liu, Xianxue
    • Journal of Magnetics
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    • v.14 no.2
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    • pp.66-70
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    • 2009
  • The dynamic magneto-mechanical behaviors in a type of iron-nickel-based ferromagnetic alloy with constant elasticity were investigated as a function of both the DC bias magnetic field ($H_{dc}$) and the frequency. The rectangular plate-like samples were excited to vibrate at a half-wavelength, longitudinal resonance by an AC magnetic field superimposed with various $H_{dc}$. The experimental results found that the strain coefficient at resonance reached 819.34 nm/A and the effective mechanical quality factor ($Q_m$) was greater than 2000. The ratio of the maximum variation of the Young's modulus over $H_{dc}$ to the value of the Young's modulus at a zero bias field was only ${\sim}0.83%o$ because of the so-called constant elasticity. The resonant strain coefficients and $Q_m$ are strongly dependent on $H_{dc}$, which indicates a promising potential for use in DC and quasistatic magnetic field sensing.

Study on an Acceleration Sensor using Magnetoelastic Effect of an Amorphous Wire (비정질 세선의 자기탄성 효과를 이용한 가속도 센서 개발에 관한 연구)

  • Cho, H.J.;Son, D.L.;Lim, S.J.;Yang, J.M.
    • Journal of Sensor Science and Technology
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    • v.2 no.1
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    • pp.11-17
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    • 1993
  • We have constructed an acceleration sensor which is based on the maximum magnetic induction changes of amorphous wire as a measurand. The frequency bandwith of the constructed sensor depends on the mass of a sensing element. For $Co_{72.5}Si_{12.5}B_{15}$ amorphous wire, the bandwith is DC-700 Hz for $1{\times}10^{-3}kg$ sensing element and DC-200 Hz for $5{\times}10^{-3}kg$. The linearity of the acceleration sensor was less than 1% within the acceleration of 5 g.

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The Monohydrogen Arsenate-sensing Electrodes (Monohydrogen Arsenate 감응 전극)

  • Gwon-Shik Ihn;Il-Bae Park
    • Journal of the Korean Chemical Society
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    • v.31 no.2
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    • pp.162-167
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    • 1987
  • Four component $Ag_2S$-PbS-$PbHAsO_4-Cu_2S$ and three component $Ag_2S$-PbS-$PbHAsO_4$ electrodes have been prepared and evaluated for the direct measurement of monohydrogen arsenate. The 3.0 : 0.5 : 1.0 : 0.25 (mole ratio, $Ag_2S$:PbS:$PbHAsO_4:Cu_2S$) composition is superior in terms of potentiometric response, stability, rapidity of response and reproducibility. Testing was done over the concentration range $10^{-1}$~$10^{-4}M\;HA_SO_4^{2-}$in 0.1F NH4Ac-NH4OH buffer solution at pH 8.50 with constant ionic strength. Interfering ions were $CN^-,\;I^-,\;S^{-2}$ and $Cl^-$.

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A Low Cost Position Sensing Method of Switched Reluctance Motor Using Reflective Type Optical-sensors (반사형 광센서를 이용한 저가형 SRM 위치검출기법)

  • Kim S.J.;Yoon Y.H.;Won C.Y.;Kim H.S.
    • The Transactions of the Korean Institute of Power Electronics
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    • v.10 no.2
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    • pp.148-154
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    • 2005
  • As the exciting point of each phase is determined by the position of rotor, the rotor's accurate position-information is needed for the Switched Reluctance Motor(SRM). When using an absolute-encoder or a resolver, to detect the location of rotor the initial starting is possible, as early sensing of rotor's location is possible. However, this is not appropriate, considering the economical efficiency, and in case of using the incremental-encoder, there's a problem at initial starting as it is not easy to track down the location of rotor at the very beginning. When using Hall-ICs, there's a fault, as it needs a special ring magnet. Considering the initial starting and economical efficiency, the optical sensor technique using a slotted-disk and an opto-interrupter is appropriate, however, this method needs three opto-interrupters and a slotted-disk when using the 6/4 pole SRM. Nevertheless, in this paper, it used only two optical sensors to operate 6/4 pole SRM and made the start up and also forward and reverse operation possible. By excluding the slotted-disc md shortening a optical sensor, it improved the convenience and economical efficiency of the production. Also, as the space for slotted-disc is no more needed, it was able to reduce the size of motor.

Fabrication of C2H2 Gas Sensors Based on Ag/ZnO-rGO Hybrid Nanostructures and Their Characteristics (Ag/ZnO-rGO 하이브리드 나노구조 기반 C2H2 가스센서의 제작과 그 특성)

  • Lee, Kwan-Woo;Chung, Gwiy-Sang
    • Journal of Sensor Science and Technology
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    • v.24 no.1
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    • pp.41-46
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    • 2015
  • In this work, pure hierarchical ZnO structure was prepared using a simple hydrothermal method, and Ag nanoparticles doped hierarchical ZnO structure was synthesized uniformly through photochemical route. The reduced graphene oxide (rGO) has been synthesized by typical Hummer's method and reduced by hydrazine. Prepared Ag/ZnO nanostructures are uniformly dispersed on the surface of rGO sheets using ultrasonication process. The synthesized samples were characterized by SEM, TEM, EDS, XRD and PL spectra. The average size of prepared ZnO microspheres was around $2{\sim}3{\mu}m$ and showed highly uniform. The average size of doped-Ag nanoparticles was 50 nm and decorated into ZnO/rGO network. The $C_2H_2$ gas sensing properties of as-prepared products were investigated using resistivity-type gas sensor. Ag/ZnO-rGO based sensors exhibited good performances for $C_2H_2$ gas in comparison with the Ag/ZnO. The $C_2H_2$ sensor based on Ag/ZnO-rGO had linear response property from 3~1000 ppm of $C_2H_2$ concentration at working temperature of $200^{\circ}C$. The response values with 100 ppm $C_2H_2$ at $200^{\circ}C$ were 22% and 78% for Ag/ZnO and Ag/ZnO-rGO, respectively. In additions, the sensor still shows high sensitivity and quick response/recovery to $C_2H_2$ under high relative humidity conditions. Moreover, the device shows excellent selectivity towards to $C_2H_2$ gas at optimal working temperature of $200^{\circ}C$.

Metal-organic frameworks-driven ZnO-functionalized carbon nanotube fiber for NO2 sensor

  • Woo, Sungyoon;Jo, Mingyeong;Lee, Joon-Seok;Choi, Seung-Ho;Lee, Sungju;Jeong, Hyeon Su;Choi, Seon-Jin
    • Journal of Sensor Science and Technology
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    • v.30 no.6
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    • pp.369-375
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    • 2021
  • In this study, heterogeneous ZnO/CNTF composites were developed to improve the NO2-sensing response, facilitated by the self-heating property. Highly conductive and mechanically stable CNTFs were prepared by a wet-spinning process assisted by the liquid crystal (LC) behavior of CNTs. Metal-organic frameworks (MOFs) of ZIF-8 were precipitated on the surface of the CNTF (ZIF-8/CNTF) via one-pot synthesis in solution. The subsequent calcination process resulted in the formation of the ZnO/CNTF composites. The calcination temperatures were controlled at 400, 500, and 600 ℃ in an N2 atmosphere to confirm the evolution of the microstructures and NO2-sensing properties. Gas sensor characterization was performed at 100 ℃ by applying a DC voltage to induce Joule heating through the CNTF. The results revealed that the ZnO/CNTF composite after calcination at 500 ℃ (ZnO/CNTF-500) exhibited an improved response (Rair/Rgas = 1.086) toward 20 ppm NO2 as compared to the pristine CNTF (Rair/Rgas = 1.063). Selective NO2-sensing properties were demonstrated with negligible responses toward interfering gas species such as H2S, NH3, CO, and toluene. Our approach for the synthesis of MOF-driven ZnO/CNTF composites can provide a new strategy for the fabrication of wearable gas sensors integrated with textile materials.

Calibration and validation of the level 2 data of the Korean OSMI ocean color satellite

  • Suh, Y.S.;Jang, L.H.;Lee, N.K.;Lim, H.S.;Kim, Y.S.;Ahn, Y.H.
    • Proceedings of the KSRS Conference
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    • 2003.11a
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    • pp.703-705
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    • 2003
  • A comparison was made between the chlorophyll a and suspended solid (SS) retrievals from OSMI and SeaWiFS sensor to chlorophyll a and SS values determined with the standard method during the NFRDI's research cruises. The percentage of organic and inorganic materials from the SS was calculated to study the contribution of turbid water in the northern part of the East China Sea. The open sea waters in the Kuroshio regions of the East China Sea showed relatively higher concentration of volatile SS. However, towards the northwestern part of the East China Sea, the situation became much more optically different with the non-volatile SS from the Yangtze river and the sea bottom sources in the sea in winter and spring seasons. Furthermore, in order to indirectly detect low salinity water with high turbidity, which related to the Yangtze river using remote sensed data from the satellites, a comparison between the results of the band ratio(nLw 490nm/nLw 555nm) of SeaWiFS (OSMI) and the distribution of low salinity around the Jeju Island was presented.

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Heterostructures of SnO2-Decorated Cr2O3 Nanorods for Highly Sensitive H2S Detection (고감도 H2S 감지를 위한 SnO2 장식된 Cr2O3 nanorods 이종구조)

  • Jae Han Chung;Yun-Haeng Cho;Junho Hwang;Su hyeong Lee;Seunggi Lee;See-Hyung Park;Sungwoo Sohn;Donghwi Cho;Kwangjae Lee;Young-Seok Shim
    • Journal of Sensor Science and Technology
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    • v.33 no.1
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    • pp.40-47
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    • 2024
  • The creation of vertically aligned one-dimensional (1D) nanostructures through the decoration of n-type tin oxide (SnO2) on p-type chromium oxide (Cr2O3) constitutes an effective strategy for enhancing gas sensing performance. These heterostructures are deposited in multiple stages using a glancing angle deposition technique with an electron beam evaporator, resulting in a reduction in the surface porosity of the nanorods as SnO2 is incorporated. In comparison to Cr2O3 films, the bare Cr2O3 nanorods exhibits a response 3.3 times greater to 50 ppm H2S at 300℃, while the SnO2-decorated Cr2O3 nanorods demonstrate an eleven-fold increase in response. Furthermore, when subjected to various gases (CH4, H2S, CO2, H2), a notable selectivity toward H2S is observed. This study paves the way for the development of p-type semiconductor sensors with heightened selectivity and sensitivity towards H2S, thus advancing the prospects of gas sensor technology.

Bio-inspired Cr2O3 and Co3O4 Nanoparticles Loaded Electrospun WO3 Nanofiber Chemical Sensor for Early Diagnosis of Halitosis (고분산성 Cr2O3 및 Co3O4 전이금속 나노입자 촉매가 기능화된 다공성 WO3 나노섬유를 이용한 구취진단용 화학센서)

  • Jang, Ji-Soo;Kim, Sang-Joon;Choi, Seon-Jin;Koo, Won-Tae;Kim, Il-Doo
    • Journal of Sensor Science and Technology
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    • v.25 no.3
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    • pp.223-228
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    • 2016
  • In this work, we prepared porous WO3 nanofibers (NFs) functionalized by bio-inspired catalytic $Cr_2O_3$ and $Co_3O_4$ nanoparticles as highly sensitive and selective $H_2S$ gas sensing layers. Highly porous 3-dimensional (3D) NFs networks decorated by well-dispersed catalyst NPs exhibited superior $H_2S$ gas response ($R_{air}/R_{gas}$ = 46 at 5 ppm) in high humidity environment (95 %RH). In particular, the sensors showed outstanding $H_2S$ selectivity against other interfering analytes (such as acetone, toluene, CO, $H_2$, ethanol). Exhaled breath sensors using $Cr_2O_3$ and $Co_3O_4$ catalysts-loaded $WO_3$ NFs are highly promising for the accurate detection of halitosis.