Low-cost particulate matter (PM) sensors based on the light scattering principle measure the concentration of particles by the change of scattering intensity after light is irradiated onto the particles. It has been reported that when the relative humidity is high, water vapor may cause the expansion of airborne particles and affect the accuracy of the light scattering method for PM measurement, but it has also been shown that the effect of humidity is not significant or even negligible. Therefore, to determine the effect of humidity on the Plantower PMS7003 light scattering sensor, in this study, a BAM1020 (Beta Attenuation Monitoring) was installed alongside to continuously monitor the ambient atmospheric PM concentration for approximately four weeks. The sensors collected data at 10-minute intervals, resulting in a 1-hour average for comparative analysis. To accurately measure humidity, the performance of the Arduino + DHT22 humidity sensor was also pre-evaluated using a series of saturated salt solutions. The humidity was grouped into five intervals and analyzed by visual analysis. The results confirmed that there was no significant correlation between PM2.5 differences and humidity, which were randomly and uniformly distributed around the mean. However, since in the very low and high concentration ranges based on the beta-ray monitor measurements, the difference between the light scattering sensor PM10 measurement and the reference value is much larger than the difference between the PM2.5 and the reference value., there is an additional need to investigate the appropriate correction method for dust season or PM10. The results show that the outcomes of the light scattering sensor are more influenced by particle size and concentration than by humidity.

The purpose of this study is to analyze the effect of temperature and humidity on the measured Particulate Matter (PM) concentrations recorded by PMS5003T, a low-cost light scattering type measuring tool. A regression analysis was performed on the ratio of PM concentrations measured by the light scattering method and the beta-ray absorption method according to temperature and humidity in an outdoor environment. As the temperature decreased, the PM concentration ratio increased, and this tendency intensified below 0oC. As the humidity increased, the PM concentration ratio increased, but the effect was less than the temperature effect. The coefficients of determination for temperature and humidity were R2 = 0.325 and 0.003, respectively, and the effects of temperature and humidity on the measured values w ere formulated and compensated for. As a result of the compensation, R2, relative precision, accuracy and RMSE improved from 0.927 to 0.958, from 91.183% to 96.651%, from 31.383% to 74.058%, and from 13.517 μg/m³ to 6.690 μg/m³, respectively. Finally, results from this study indicate that the reliability of the low-cost light scattering type PM sensor can be improved by applying the temperature and humidity compensation method.

The present paper describes the effect of co-catalyst on the growth of multiwall carbon nanotube (MWCNT) by chemical vapor deposition (CVD) technique. The fascinating properties of CNT make them a suitable material for optoelectronic devices such as sensors, LED, solar cell, and field emission displays. MWCNTs were fabricated using CVD, by decomposing ethanol over finely dispersed Co metal as a catalyst at 750 °C. The effects of growth condition on the quality and morphology of MWCNTs were investigated by SEM, FTIR and XRD. SEM photographs show that the nanotubes are densely packed having a diameter of 10–15 nm. The bandgap was calculated by UV–visible spectroscopy and it was found varying from 3.08 to 3.5 eV by changing the substrates. The average size of tubes (length) was found to be 250 nm. FTIR exhibited that the synthesized MWCNTs were semiconducting in nature with the oxygen vacancies causing the variations in refractive index with the exposure of moisture.

The study analyzed performance assessment factors of odor sensors from 4 different manufacturers, including minimum detection limit, humidity stability and temperature stability. In the minimum detection limit assessment, only one electrochemical gas sensor was able to detect ammonia and hydrogen sulfide at the concentration of 5 ppb. The standard deviation ratio was over 10%, and it increased as humidity rose. The range of temperatures in which the electrochemical and photoionization gas sensors could function well was between 25oC and 40oC, and the sensor output values were unstable at low temperatures. Regarding the temperature stability of the metal oxide semiconductor sensor for measuring complex odors, the sensor output values dropped considerably to 0~10oC, and were similar to the concentrations of odor gases generated at 25oC. The results of the test of odor sensor outputs after temperature and humidity pre-treatment revealed that the respective stable output values at 50% humidity and 25oC were similar to the concentrations of manufactured odors. In terms of temperature and humidity stability of the NH3, H2S and Complex odor sensors, all target substances had stable output values at 25~40oC and 50~65% relative humidity, and unstable values at low temperatures and high humidity. Therefore, implementing pretreatment systems including temperature and humidity correction (25~40oC, 50~65% RH) is necessary for the stable use of odor sensors.

4 차 암모늄염을 형성할 수 있는 공중합체들 poly[(vinylbenzyl chloride)-co-(n-butyl acrylate)-co-(2-hydroxyethyl methacrylate)]와 poly[(4-vinylpyridine)-co-(n-butyl acrylate)-co-(2-hydroxyethyl methacrylate)]를 고분자막 습도센서의 감습재료로 사용하기 위하여 합성하였다. 습도센서는 30%RH, 60%RH 그리고 90%RH에서 평균 저항 값은 각각 8.6 M Ω, 310 kΩ 그리고 12 kΩ을 보여 주었다. 또한 히스테리시스는 ±3%RH 안에서 나타났으며, 온도의존성 계수는 -0.37~-0.407RH/˚C이었다. 감습막의 조성에서 공중합체 중 n-BA와 HEMA의 도입은 저항을 증가시키는 요인이 되나 기판과의 접착성은 크게 향상되었다. 33%RH에서 85%RH로 또는 역으로 변화할 때의 응답속도는 54초이며 수중에 2시간 침적 후 저항의 변화는 +0.2%RH 이내에서 존재하였다.

고분자막 습도센서의 감습재료로 사용하기 위하여 vinylbenzyl chloride (VBC), methyl methacrylate (MMA) 그리고 2-hydroxyethyl methacrylate (HPMA)의 여러 가지 조성의 공중합체를 합성하여, 이를 전극에 도포하고 N, N, N', N'-tetraethylene diamine으로 4차 암모늄화 시켜 최종 습도센서를 제조하였다. 상대습도에 따른 저항 변화를 측정한 결과, 공중합체에서 MMA의 조성이 증가하면 저항이 증가하였으며, HEMA의 도입은 친수성기의 작용으로 저항의 증가는 크지 않았으며 강습막의 기판과의 접착성은 크게 향상되었다 또한 VBC/MMA/HEMA=80/10/10의 경우 히스테리시스는 ±2%RH 안에서 나타났으며, 온도의존성 계수는 -0.42~-0.46%RH/˚C이었다. 30%RH, 60%RH 그리고 90%RH에서의 저항 값은 각각 3.0MΩ,,200kΩ 그리고 9kΩ 이었다

Prediction of compressive strength of concrete by Maturity Method is applied in construction site. However, due to the use of wired type high-priced equipment, economic efficiency and workability are falling. In this study, a newly developed concrete embedded wireless sensor is used to perform a mock-up test. Next, the concrete compressive strength of the Maturity Method is predicted using Saul and Plowman's function as measured temperature data. The predicted concrete strength at the beginning of the age was the actual strength and stiffness, but the error rate was less than 1% at 28th day.

Prediction of the compressive strength of the maturity method has been studied by several researchers and has been applied to the construction of concrete structures. In order to apply the maturity method, which is a function related to temperature and time, it is important to measure the accurate temperature inside the concrete during the curing period. The purpose of this study is to verify the performance by analyzing sensitivity, measurement and transmission accuracy by exposing wireless embedded sensor to various curing environment.