• 전기학회논문지
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• 제59권7호
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• pp.1302-1308
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• 2010

In this study, Zigbee Sensor Node to transmit harmful gases CO and $CO_2$ information using wireless communication within the ground and underground structures were developed. Wireless communication protocol was used Zigbee Stack included IEEE 802. 15.4 MAC protocol. For wireless transmission of detected harmful gas signal from ADC of MCU was implemented Zigbee Sensor Node that was developed protocol using Serial-Port-Profile(SPP) here. The proposed Zigbee Sensor Node was verified transmission distance from experiments. Transmission distance was into 90m in experiments. Distance experiments were measured at 10m intervals using sine & pulse wave input signal at indoors. The proposed Route Sensor Node was applied mesh routing protocol. When built up USN(Ubiquitous Sensor Network)using Route Sensor Node, transmission distance was not limited. On the experimental results, harmful gas values between direct measurements and USN measurements were consistent. The semiconductor CO sensor and N-DIR $CO_2$ sensor module as a harmful sensor was used. Therefore, the proposed Zigbee Sensor Node was verified about reliability and validity to build USN for transmission of harmful gas information.

• 센서학회지
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• 제23권3호
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• pp.170-172
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• 2014

$CO_2$ sensor was used only one solid electrolyte in many cases. To improve the sensing characteristics of $CO_2$ sensors, solid electrolyte $CO_2$ sensor has been developed by bi-electrolyte type sensor using Na-Beta-alumina and YSZ. However, in many further studies, bi-electrolyte type sensor was made by pellet pressed by press machine and additional treatment for formation of interface. In the aspect of mass production, using thick film and additional treatment is not suitable. In this study, $CO_2$ sensor was fabricated by bi-electrolyte structure which was made by an NBA paste layer deposited on YSZ pellet and fired at $1650^{\circ}C$ for 2 hour. The formation of stable interface between YSZ and NBA were confirmed by SEM image. When the type IV electrochemical cell arrangement represented by $CO_2,O_2,Pt{\mid}Li_2CO_3-CaCO_3{\parallel}NBA{\parallel}YSZ{\mid}O_2,Pt$ is used to measure the $CO_2$ concentration in air. This sensor EMF should depend only on the concentration of $CO_2$ by logarithmic. Also, sensor shows $P_{CO_2}$ and EMF relationship like nerstian reaction at a temperature of $450^{\circ}C$.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제54권5호
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• pp.232-237
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• 2005

In this paper, we fabricated $CO_2$ gas sensor based on the MEMS infrared sensor and characterized its electrical and $CO_2$-sensing properties. The fabricated $CO_2$ gas sensor by MEMS technique has many advanges over NDIR(nondispersive) $CO_2$ sensor such as monolithic fabrication, very high selectivity on $CO_2$, low power consumption and compact system. Microbolometer by surface micromachining was fabricated for gas detector and $CO_2$ filter chip by bulk micromachining was fabricated for signal referencing. By using the proposed and fabricated gas sensor, we are expected to measure $CO_2$ concentration more accurately with high reliability.

• Bulletin of the Korean Chemical Society
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• 제33권4호
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• pp.1297-1302
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• 2012

The interaction between carbon monoxide (CO) and a cobalt-salen complex (Co(salen)) was studied and applied to detect CO. The metal complex doped PEDOT:PSS film exhibited good sensitivity to CO and differentiate CO from other gases. The response of the composite to CO was reversible (RSD < 5%) change in resistance upon removal of CO gas from the test chamber. The effects of adding Co(salen) in the probe film on the response of the sensor were investigated using AFM, XPS, and FT-IR spectroscopy. The sensitivity of the sensor increased as the Co(salen) concentration enhanced as it increased from 0.0 to 1.5 wt. %, where the highest sensitivity ($%{\Delta}R/R_o$) of $-25.0{\pm}0.05%$ was achieved with 1.0 wt. % Co(salen). The sensor containing probe exhibited a linear response ($R^2$ = 0.983) in the range of 0.5 to 10.0% CO (v/v) $N_2$, and the detection limit was 1.74% CO (v/v) in $N_2$.

• 센서학회지
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• 제18권5호
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• pp.343-348
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• 2009

$NiO{\cdot}(Co_{0.25}Mn_{0.75})_2O_3$(Mn-Ni-Co) and $Ba_{0.5}Sr_{0.5}TiO_3$(BST) thick films were screen printed on Pt patterned alumina substrate to investigate the effects of sintering temperature on humidity and temperature sensing properties of ceramic sensors. A raise in sintering temperature increased resistance and B constant of the Mn-Ni-Co temperature sensor. This may have derived from the synergic effects of the reduction in charge carriers caused by the substitution of Co for Mn as well as the formation of microcracks from the difference in thermal expansion coefficients. Dependence of resistance on humidity of the Mn-Ni-Co temperature sensor, however, was not found. BST films sintered at temperatures in the range of $1100^{\circ}C$ to $1150^{\circ}C$ showed excellent humidity sensing properties. The BST humidity sensor was faster in its response than the Mn-Ni-Co temperature sensor. The humidity sensor, however, proved to be unstable under various temperatures, suggesting a need for a temperature stabilizing device. In contrast, the Mn-Ni-Co temperature sensor was stable under humid conditions.

• 전기학회논문지P
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• 제66권2호
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• pp.82-87
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• 2017

This paper presents performance improvement of CO gas sensor signal conditioner for early fire warning system. The warning system is based on the CO sensor and its advanced signal conditioning modules network that employ electochemical gas sensor. The electochemical has advantage of having a linear output and operating with a low consumption and fast response. This electrochemical gas sensor contains a gas membrane and three electrodes(working, counter, reference electrode) in contact with an electrolyte. To use a three-electrode sensor, a voltage has to be applied between the working and the reference electrode according to the specification of the sensor. In this paper, we designed these requirements that should be considered in temperature compensation algorithm and electrode measurement of CO sensor modules by using advanced signal conditioning method included 3-electrode. Simulation and experimental results show that signal conditioner of CO sensor module using 3-electrode have a advantage linearity, sensitivity and stability, fast response etc..

• 센서학회지
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• 제25권2호
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• pp.124-130
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• 2016

NDIR $CO_2$ gas sensor was built with ASIC implemented thermopile sensor which included temperature sensor and unique elliptical waveguide structures in this paper. The temperature dependency of dual infrared sensor module ($CO_2$ and reference IR sensors) has been characterized and its output voltage characteristics according to the temperature and gas concentration were proposed for the first time. NDIR $CO_2$ gas and reference IR sensors showed linear output voltages according to the variation of ambient temperatures from 243 K to 333 K and their slopes were 14.2 mV/K and 8.8 mV/K, respectively. The output voltages of temperature sensor also presented a linear dependency according to the ambient temperature and could be described with V(T)=-3.191+0.0148T(V). The output voltage ratio between $CO_2$ and reference IR sensors revealed irrelevant to the changes of ambient temperatures and gave a constant value around 1.6255 with standard deviation 0.008 at 0 ppm. The output voltage of $CO_2$ gas sensor at zero ppm $CO_2$ gas consisted of two components; one is caused by the HPB (half pass-band) of IR filter and the other is attributed to the part of $CO_2$ absorption wavelength. The characteristics of output voltages of $CO_2$ gas sensor could be accurately modeled with three parameters which are dependent upon the ambient temperatures and represented small average error less than 1.5% with 5% standard deviation.

• 전자공학회논문지
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• 제52권3호
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• pp.39-47
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• 2015

본 논문은 센서 네트워크에서의 CoAP(Constrained-Application Protocol)을 이용한 시각 동기화 기법에 관한 것으로 별도의 시각 장치를 내장하지 않은 센서 노드와 인터넷을 통해 시각 서버에 연결된 센서 노드 중계기 간 시각을 동기화하는 기술에 관한 것이다. CoAP은 전송 지연 및 패킷 손실 등 제한된 네트워크 환경에서 저수준의 성능을 갖는 센서노드를 통해 센서 데이터를 전송할 수 있도록 지원하는 프로토콜이다. 본 논문에서는 CoAP의 옵션 확장을 통해 저가의 IP기반 소형 센서 노드나 따로 IP에 연결되지 않은 센서 노드로부터 센서 노드 중계기 간의 센서 데이터 수신 시각을 정확히 동기화 설정 할 수 있도록 한다. 기존에 사용 중인 범용 프로토콜 대신, 센서 네트워크에서의 전용 프로토콜인 CoAP을 사용함으로써, 부가적인 센서 노드나 중계기에서의 서비스 부담 없이 이용 가능 하다. CoAP을 이용한 시각 동기화 기법은 NTP(Network Time Protocol) 대비 평균 2ms 내의 오차를 가지며, 저비용으로 강건한 시각 동기화 기법을 제공한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.221-221
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• 2010

수배전반 내부에서 Arc 사고 발생시 동반되는 광신호를 검출할 수 있는 광센서를 개발하였다. 개발된 광센서는 특정 부위에 설치되어 해당 위치에서 발생하는 광신호를 검출하는 Point Sensor와 넓은 범위를 감시할 수 있는 Loop Sensor의 두 가지 형태로 구성되어 있다. 두 가지 모두 광섬유를 통하여 계전기 등에 부착되며, 일반 통신용 광섬유보다 큰 core를 갖는 특수 광섬유가 사용되었다. Point Sensor는 광섬유 끝단에 부착된 Cap에 의해 광신호가 검출되고, Loop Sensor는 광섬유 자체가 Sensor로 사용되어 광신호의 검출 및 전승을 수행한다. Point Sensor에 부착되는 Cap은 보다 넓은 범위 감시하고, 광신호 발생 위치에 따른 편차를 줄일 수 있는 형태로 설계되었다.

• 한국화재소방학회논문지
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• 제28권2호
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• pp.54-63
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• 2014

본 논문은 CO센서의 화재에 대한 감지특성을 분석 후 화재감지기로서의 적용성 판단을 하기 위한 논문이다. CO센서의 화재감지기로의 적용성을 판단하기 위해 UL 268에서 규정하고 있는 화재시험실과 유사한 규모의 화재실험장을 설계 제작하고, UL 268에서 제시된 화재시험기준에 준한 실화재실험을 실시하여 화원 종류에 따른 CO센서와 광전식연기감지기의 다양한 화원의 화재에서 발생하는 일산화탄소와 연기에 대한 감지특성을 측정하여 비교 분석하였다. 실험결과 종이화원 및 목재화원과 같이 불완전연소로 진행되는 초기화재에서 CO센서가 광전식연기감지기보다 약 2~3배 빠른 감지특성이 나타났다. 특히, 목재훈소화재에서 CO센서의 감지특성이 매우 우수한 것으로 나타났다.