• 한국전기전자재료학회논문지
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• 제13권10호
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• pp.865-870
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• 2000

In this paper, catalytic combustible gas sensor was fabricated and tested under flammable gases such as CH$_4$and $C_4$H$_{10}$by using Pt coil as a heater and/or temperature sensing element. Fine $Al_2$O$_3$powder was used for a bead and Pt, Pd noble metal powder for a catalyst. Resistance variation of Pt wire was traced by the changes of the gas concentrations in a chamber. Output voltage was then monitored to obtain the gas concentration from the resistance variation. In this experiment, MgO was used to protect cracks in the based and TiO$_2$to increase the sensitivity of the sensors. Water glass was also added to enhance the selectivity to the combustible gases.s.

• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.812-817
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• 2008

A catalytic combustible sensor for LPG/LNG detection was fabricated on $Al_2O_3$ substrate using planar technology. The catalysts of Pd and Pt were added to ${\alpha}$- and ${\gamma}-Al_2O_3$ powders. The mixture of Pt, Pd and $Al_2O_3$ were homogenized by using a three roll mixer. TCR characteristics of Pt heater were optimized with the heat treatment temperature. Sensing properties were investigated as a function of the microstructure of $Al_2O_3$, the gas concentration and the variation of input voltage. ${\alpha}-Al_2O_3$ sintered at 500 $^{\circ}C$ is more suitable as LPG/LNG sensor due to good grain shape and size distribution of about 300 nm than that of ${\gamma}-Al_2O_3$ which is in irregular shape and with a particle size of 5-30 ${\mu}m$. The sensor has shown maximum output voltage of 14 mV for 1000 ppm $C_4H_{10}$ and 3.8 mV for 1000 ppm $CH_4$ at 5.0 V input voltage.

• 센서학회지
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• 제17권3호
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• pp.178-182
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• 2008

Planar type micro catalytic combustible gas sensor was developed by using nano crystalline $SnO_2$ Pt thin film as micro heater was deposited by thermal evaporation method on the alumina substrate. The thickness of the Pt heater was around 160 nm. The sensor showed high reliability with prominent selectivity against various gases(Co, $C_3H_8,\;CH_4$) at low operating temperature($156^{\circ}C$). The sensor with nano crystalline $SnO_2$ showed higher sensitivity than that without nano crystalline $SnO_2$. This can be explained by more active adsorption and oxidation of hydrogen by nano crystalline $SnO_2$ particles. The present planar-type catalytic combustible hydrogen sensor with nano crystalline $SnO_2$ is a good candidate for detection of hydrogen leaks.

• 센서학회지
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• 제18권3호
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• pp.202-206
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• 2009

Flat type catalytic combustible hydrogen sensors were fabricated using platinum micro-heaters and sensing material pastes. The platinum micro-heater was formed on an alumina substrate by sputtering method. The paste for the sensing materials was prepared using ${\gamma}-Al_2O_3$ 30 wt%, $SnO_2$ 35 wt%, and Pd/Pt 30 wt% and coated on the platinum micro-heater. The sensing performances were tested for the prepared sensors with different substrate sizes. The micro catalytic combustible hydrogen sensors showed quick response time, high reliability, and good selectivity against various gases(CO, $C_3H_8,\;CH_4$) at low operating temperature of $156^{\circ}\C$.

• 센서학회지
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• 제15권1호
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• pp.34-39
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• 2006

This study provides the electrical model of combustible catalytic gas sensor. Physical characteristics such as thermal behavior, resistance change were included in this model. The finite element method analysis for sensor device structure showed that the thermal behavior of sensor is expressed in a simple electrical equivalent circuit that consists of a resistor, a capacitor and a current source. This thermal equivalent circuit interfaces with real electrical circuit using two parts. One is 'power to heat' converter. The other is temperature dependent variable resistor. These parts realized with the analog behavior devices of the SPICE library. The gas response tendency was represented from the mass transferring limitation theory and the combustion theory. In this model, Gas concentration that is expressed in voltage at the model, is converted to heat and is flowed to the thermal equivalent circuit. This model is tested in several circuit simulations. The resistance change of device, the delay time due to thermal capacity, the gas responses output voltage that are calculated from SPICE simulations correspond well to real results from measuring in electrical circuits. Also good simulation result can be produced in the more complicated circuit that includes amplifier, bios circiut, buffer part.

• 한국가스학회:학술대회논문집
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• 한국가스학회 1997년도 추계학술발표회 논문집
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• pp.229-235
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• 1997

A low power (300 mW) catalytic bead combustible gas sensor is developed and utilized with a computer controlled sampling system for measuring heat content of natural gas. The heat content of gas is proportional to the change in the energy required to exposure to the sample of combustible gas. The heat content of natural gas samples ranging 36.30 - 39.88 MJ/$m^3$ is measured in the range of approximately $1\%$ error, which is comparable to its nominal heat content. Each gas has a slightly different curve of sensitivity vs. sensor temperature. Thus there Is no temperature at which all sensitivities are equal. In calibration process the choice of a optimum operating temperature is an important factor that influences the overall performance of the measurement system.

• 센서학회지
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• 제3권3호
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• pp.9-15
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• 1994

비표면적이 큰 ${\gamma}-Al_{2}O_{3}$와 귀금속 촉매를 이용하여 접촉연소식 가스감지소자를 제조하였다. DT/TGA와 XRD 실험을 통해 ${\gamma}-Al_{2}O_{3}$ 제조의 최적 조건을 구하였으며, 제조된 ${\gamma}-Al_{2}O_{3}$는 $215.5m^{2}/g$의 큰 비표면적을 나타내었다. Pt 코일을 발열체 및 온도감지소자, 미세 ${\gamma}-Al_{2}O_{3}$ 분말을 담체 모물질, Pd 및 Pt 귀금속을 촉매제로 이용하여 가스센서를 제조하고 가연성 가스에 대한 감도특성을 조사하였다. 실험결과들로부터 본 연구에서 제조된 센서는 1000ppm의 LPG 및 LNG에 대해 각각 20mV와 6.5mV로 놀은 감도 특성을 나타내었다.

• 한국가스학회지
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• 제2권1호
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• pp.1-6
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• 1998

전력을 적재 소모하는 (300 mW 이하) 촉매가스센서가 개발되었고, 천연가스에 열용량을 측정하기 위해 컴퓨터로 작동되는 샘플링 시스템에 사용되었다. 가스의 열용량은 촉매자스센서가 감지되는 연소가스에 노출되었을 때 발생된 에너지에 비례된다. 36.30 - 39.88 $MJ/m^3$ 범위의 정격 열용량을 갖는 천연가스의 열용량은 약 $1\%$ 에러 내에서 측정되었다. 각 가스들은 센서의 온도에 대하여 약간씩 다른 감응곡선을 갖고 있다. 따라서 한 온도에서 모든 감응이 같을 수는 없다. 작동 온도는 측정장치의 전 성능에 영향을 미치기 때문에 교정과정에서 최적의 작동 온도를 찾는 것은 중요하다.

• 센서학회지
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• 제5권1호
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• pp.23-29
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• 1996

본 연구에서는 스크린 프린팅 기술을 이용한 병렬저항열원을 갖는 후막형 가연성 가스센서를 제조하고, 메탄 가스에 대한 감도특성을 조사하였다. 알루미나 기판의 양면 위에 제조된 병렬형 백금 후막발열체는 후막형백금 저항체의 온도 감지 특성과 표면 특성을 조사하여 백금페이스트 TR7905 제품을 선정하였다. 제조된 백금 후막 발열체는 평균저항같이 $1.8{\Omega}$이고, TCR값은 $3685\;ppm/^{\circ}C$이었다. 제조된 백금 발열체상에 Pt과 Pd이 첨가된 촉매 페이스트를 제조하고 감지부는 Pt과 Pd가 첨가된 촉매를 스크린 프린팅하여 후막을 형성하고 열처리하여 제조하였다. 제조된 후막형 센서는 메탄 가스에 대해 4.3mV/1000ppm의 감도를 보였으며, 소비전력은 2.12W이었다.