• International Journal of Highway Engineering
• /
• v.7 no.3 s.25
• /
• pp.23-30
• /
• 2005

Predicting distribution and variation of humidity inside concrete is essential to improve curing quality of concrete at field. The concrete humidity is predicted by numerical analysis using surface humidity as boundary condition. However, ambient humidity has been used instead of the surface humidity because the surface humidity could not be ccurately measured. Because it is hard to accurately measure the surface humidity, owever, the ambient humidity has been used instead of the surface humidity in the numerical analysis. In this paper, a methodology to accurately measure the surface humidity is suggested, and the ambient humidity and the humidity at the surface and inside the concrete measured by a series of laboratory tests are presented. The cause of low concrete humidity immediately after placement was investigated by a separately performed test. A surface humidity prediction model was developed using the measured humidity, and consequently validated through an additional test.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.307-308
• /
• 2021

Corrosion of reinforced steel inside concrete is an important cause of performance degradation of reinforced concrete structures and has a profound influence on the durability of structures. In this study, three groups of different reinforced concrete structures exposed to the natural environment were subjected to chloride ion accelerated corrosion tests for up to 180 days. The corrosion velocity and ambient temperature of the samples were measured and recorded every day. Based on Faraday's law, the corrosion speed of steel bars could be measured, and the ambient temperature and humidity around the structure in corresponding time were compared. Through the measurement of up to 180 days, the influence of external ambient temperature and humidity on the corrosion speed of steel bars inside the concrete structure was found out. The results show that there is a good direct proportional relationship between temperature and corrosion speed. When the ambient temperature increases by 15℃, the corrosion rate increases by about one time.

• Journal of Korean Society for Atmospheric Environment
• /
• v.20 no.2
• /
• pp.161-174
• /
• 2004

Aerosol formation and growth by water vapor reactions were investigated in a 2.5 -㎥ indoor smog chamber filled with the unfiltered ambient air. The relative humidity of test ambient air was elevated at 59～64% or 84～88% by adding water vapor. The aerosol number size distribution and the concentrations of $O_3$, NO, NO$_2$, and SO$_2$ were measured during the experiments. The $O_3$ and NO$_2$ gases were well reacted with the water vapor at high relative humidity of 84～88%, and the reaction rates of these gases seemed to be decreased at low relative humidity of 59～64%. The formation and condensational growth phenomena of ambient aerosols by water vapor reactions were observed in a Teflon bag, depending strongly on the initial particle size distribution. The water vapor reactions might be affected by the contents of oxidants produced by photochemical reactions under sunlight.

• Journal of Power Electronics
• /
• v.15 no.3
• /
• pp.841-848
• /
• 2015

As a vital part of renewable energy and electrical traction, power converters are supposed to have high reliability and good performance. However, power semiconductors produce considerable heat when the power converter works, which results in high junction temperatures that lower the reliability and performance of the power semiconductors. Many studies show that ambient humidity has a significant effect on power devices, but the influence of high humidity on junction temperatures has yet to be studied. Therefore, this paper presents a thermal model for power converters in moist air to obtain the junction temperature increase, which is utilized for the power converter used in a Switched Reluctance Motor System. Simulation results show that the law of converter temperature distribution is independent of the relative humidity in the case of fixed ambient temperature, whereas the temperature in the power converter decreases as the ambient relative humidity increases. These simulation results are validated with the experimental results.

• Journal of the Korean Society for Precision Engineering
• /
• v.32 no.2
• /
• pp.185-190
• /
• 2015

This paper presents a new method to determine sensitivity coefficients of temperature and humidity of torque transducers by using a natural and seasonal variation of ambient conditions at the laboratory. We had measured the sensitivities of the torque transducers over almost one year using the KRISS 2 kN m torque standard machine. The sensitivity data acquired at various ambient conditions were processed using our measurement model to extract the sensitivity coefficients of temperature and humidity simultaneously with high precision. A comparison with a previous method using an environmental control chamber was carried out to test the feasibility of using our new method. Two results agreed within the uncertainty. We revealed that the torque measuring errors could be 8 times higher than the measurement and calibration capability of KRISS torque standard machine if the sensitivity changes due to the temperature and humidity are not properly corrected during a calibration.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.34 no.5
• /
• pp.314-320
• /
• 2021

Controlling ambient humid condition through high performance humidity sensors has become important for various fields, including industrial process, food storage, and the preservation of historic remains. Although aerosol deposited humidity sensors using ceramic BaTiO₃ (BT) material have been widely studied because of their longtime stability, there remain critical disadvantages, such as low sensitivity, low linearity, and slow response/recovery time in case of the sensors fabricated at room temperature. To achieve superior humidity sensing properties even at room temperature condition, BT-Cu composite films utilizing aerosol deposition (AD) process have been proposed based on the percolation theory. The BT-Cu composite films showed gradually improved sensing properties until the Cu concentration reached 15 wt% in the composite film. However, the excessive Cu (above 30 wt%) containing BT-Cu composite films showed a rapid decrease of the sensing properties. The results of observed surface morphology of the AD fabricated composite films, to figure out the metal filler effect, showed correlation between surface topography as well as size and the amount of open pores according to the metal filler content. Overall, it is very important not only dielectric constant of the humidity sensing films but also microstructures, because they affect either the variation range of capacitance by ambient humidity or adsorption/desorption of ambient humidity onto/from the humidity sensing films.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2021.05a
• /
• pp.197-198
• /
• 2021

The temperature and humidity inside concrete affects the depth of carbonation. In this study, the temperature and humidity inside concrete were predicted by the numerical method under the boundary conditions of ambient temperature, humidity, solar radiation, and wind. Using the results of the thermal humidity analysis, diffusion of carbon dioxide and the reaction of cement hydration products were calculated for carbonation depth.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 1998.10a
• /
• pp.131-138
• /
• 1998

It is essential that hard disk drives perform reliable under various temperature, humidity, and ambient pressure conditions. In this paper the tribological characteristics of a head/disk interface are investigated under various environmental conditions. Specially, Contact-Start-Stop(CSS) tests were performed to assess the stiction and slider take-off behavior. It is shown that the surface damage is accelerated by high temperature and humidity as well as low ambient pressure.

• Architectural research
• /
• v.9 no.2
• /
• pp.37-45
• /
• 2007

The proliferation of the House Dust Mite(HDM) is affected by temperature, humidity, ventilation, etc. Measuring temperature and humidity was performed at the very location where dust samplings take place and where they live in reality together with temperature and humidity of the ambient of the room. There has been discussion over the key environment factor of HDM survival; absolute humidity or relative humidity. It seems that relative humidity is the more important determinant for the mite's survival through the analysis of previous studies. Temperature, humidity, ventilation rate and Der P1 were measured in 4 flats in London. Mite allergen was detected in every house. Levels of Der P1 varied between <100ng/g and 22,778ng/g. Flats with high relative humidity(>50%) and poor ventilation(<0.5ach) showed higher levels of mite allergen than flats with lower humidity and adequate air change rate. Questionnaire survey was conducted and the result helped to confirm the findings from monitoring of environmental factors and the dust sampling.

• Macromolecular Research
• /
• v.13 no.2
• /
• pp.96-101
• /
• 2005

Thin-film humidity sensors were prepared using inorganic/organic hybrid polyelectrolytes, which were prepared from the sol-gel reaction of copolymers of [2-(methacryloyloxy)ethyl]dimethylpropylammonium bromide (MEPAB), n-butyl methacrylate (BMA), and 3-(trimethoxysilyl)propyl methacrylate (TSPM) with tetraethyl ortho-silicate (TEOS). The humidity-sensitive polyelectrolytes were composed of the copolymers having the following mole ratios of MEPAB, BMA, and TSPM: 60/30/10, 55/30/15, and 50/30/20. We found that the impedance varied with the content of MEPAB or TEOS; it ranged from $10^{7} to 10^{3}\Omega$ between 20 and $95\%$ relative humidity, which is the range required for a humidity sensor operating at ambient humidity. In addition we investigated a number of characteristics of these humidity sensors, such as their hysteresis, response time, temperature dependence, frequency dependence, water durability, and long-term stability.