• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.3
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• pp.19-31
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• 2007

Humidity and strain were estimated for understanding the relation between humidity change by self-desiccation and shrinkage in high-performance concrete with low water binder ratio and containing fly ash and blast furnace slag. Internal humidity change and shrinkage strain were about 10%, 10%, 7%, 11%, 11% and $320{\times}10^{-6}$, $270{\times}10^{-6}$, $231{\times}10^{-6}$, $371{\times}10^{-6}$, $350{\times}10^{-6}$ respectively on OPC30, O30F10, O30F20, O30G40, O30G50 and from the results, fly ash made humidity change and strain decrease but slag increase comparing with ordinary portland cement. Considering only relation internal humidity and shrinkage by self-desiccation, humidity change and shrinkage represented the strong linear relation regardless of mineral admixture. For specifying the relation on internal humidity change and autogenous shrinkage strain, shrinkage model was established which is driven by capillary pressure in pore water and surface energy in hydrates on the assumption of a single network and extended meniscus in pore system of concrete. This model and experimental results had a similar tendency so it would be concluded that the internal humidity change by self-desiccation in HPC originated in small pores less than 20nm, therefore controlling plan on autogenous shrinkage might be focused on surface tension of water and degree of saturation in small pore.

• Journal of Animal Science and Technology
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• v.63 no.4
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• pp.790-798
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• 2021

The objective of this study was evaluation of pig behavior changes related to temperature, relative humidity, volatile organic compounds (VOCs), and illuminance. A total of 24 growing pigs ([Yorkshire × Landrace] × Duroc) were used in the experiment. A sensor was installed at a height of 0.5 m in the center of the pig house. In experiment 1, temperature was changed every four days to 18℃ (T1), 22℃ (T2), 26℃ (T3), and then 30℃ (T4). In experiment 2, relative humidity was adjusted to 45% (low humidity [LH]), 60% (middle humidity [MH]), and then 75% (high humidity [HH]) for four days. In experiment 3, after cleaning the pig house just before experiment, only minimal ventilation was provided. VOCs and pig behaviors were observed for 7 days without cleaning the pig house. In experiment 4, three light bulbs of 40 W (470 lumens / 45 lx; low illuminance [LI]), 75 W (1,055 lumens / 103 lx; middle illuminance [MI]), and 100 W (1,521 lumens / 146 lx; high illuminance [HI]) were used for four days each. Pig behavior analysis was performed for following criteria : Feed intake, Standing, Lying, Sitting, Drink water, Rooting, Posture transition (lying-standing), Posture transition (standing-lying), Wallowing, and Biting. In experiment 1, feed intake time was lower (p < 0.05) for the T3 than other treatment groups. Standing time was highest (p < 0.05) for the T1 and lowest (p < 0.05) for the T3. Lying time was shorter (p < 0.05) in T1 and T2 compared to T3 and T4. Drinking frequency was higher (p < 0.05) for the T4 than other treatment groups. In experiment 2, the frequency of rooting and wallowing increased (p < 0.05) with increasing humidity. LH showed the lowest (p < 0.05) rooting frequency and HH showed the highest (p < 0.05) rooting frequency. In experiment 3, VOCs concentration did not (p > 0.05) change pig behavior. In experiment 4, lying time was the longest (p < 0.05) at LI and shortest (p < 0.05) at HI. Therefore, pig behavior is heavily influenced by the environment, especially temperature and humidity. However, correlation between pig behavior to VOCs and illuminance seems to be needed more research.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.319-322
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• 2009

This paper investigated environmental effects for passive, air-breathing, and vapor-feeding direct methanol fuel cells. In these experiments, experimental parameters are temperature($30^{\circ}C$, $40^{\circ}C$ and relative humidity(25%, 50%, 75%). From these experimental results, the water contents play a key role in terms of optimal ionic conductivity at the cathode catalyst layer. In case of pure methanol feeding, the performance is inversely proportional to the relative humidity. The water generation resulting from methanol crossover maintains ionic conductivity at the cathode. On the contrary, diluted methanol solution (50wt.%) lowers methanol crossover to the cathode. In order to increase ionic conductivity, the relatively high humidity is required to the cathode catalyst layer for the water generation. The relative humidity scales with the performance.

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

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.876-881
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• 2001

DLC(Diamond-like carbon) films possess high hardness, low friction coefficient, and good wear resistance. Due to these properties, DLC films have been used extensively in magnetic hard disk industry. The objective of the present study was to investigate the influence of environmental condition on the tribological behavior of DLC coated hard disk. It is found that the tribological characteristics of DLC films are strongly affected by relative humidity and temperature. Specifically, the friction coefficient increases with increase in temperature at relative humidity of 50%. However, at 20% and 85% RH the effect of temperature was not significant. Also, the degree of wear could be observed using an AFM.

• Journal of the Korea Institute of Military Science and Technology
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• v.9 no.1 s.24
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• pp.13-23
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• 2006

A propellant mainly consisting of nitric ester including nitrocellulose and nitroglycerine is characteristic of being decomposed naturally. And this phenomenon is known as being affected mostly by its storing temperature and humidity. In this research, the effect of storing temperature and humidity on self life has been studied by measuring the contained quantity of residual stabilizer of propellant KM30Al, which are parts of 155MM propelling charge K676 and K677; the method for the measurement is acceleration aging test, and decomposition reaction equation, Eyring Equation and Berthlot Equation were used for the calculation. As result of this study, it was found that the storing temperature influenced seven times as large as the storing humidity upon the self life of the propellant KM30Al, Furthermore, especially in the high temperature region, the storing temperature had a dominant effect on the self life.

• Electrical & Electronic Materials
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• v.7 no.4
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• pp.325-330
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• 1994

In this paper, $TiO_2$ thin films were fabricated by Sol-Gel method and their electrical conductivity and humidity sensing properties have been investigated. The structure of Sol can be changed by controlling for hydrolysis condition. The uniform surface of thin films was confirmed by SEM. The electrical conductivity of thin films decreased with increasing heat treatment temperature. The humidity sensing properties of thin films were good in high humidity and low frequency regions.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2589-2593
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• 2008

In a fuel cell vehicle using polymer electrolyte membrane fuel cell(PEMFC), hydrogen is over-supplied to gain higher stack efficiency. So it is needed considering fuel efficiency to re-circulate hydrogen which is not reacted in stack. And to re-circulate hydrogen, a blower or an ejector is used. Ejector re-circulation system has several merits compared with blower system, for example no parasite energy, simple structure and no lubrication system. But the secondary flow of an ejector in fuel cell vehicle, has high humidity because of crossover problem in stack. Therefore in this paper, ejector is designed by 1-D modeling and CFD with the primary and secondary flow of hydrogen. And the ejector which has the primary and secondary flow of air, is designed to have the same Reynolds number and Mach number at the nozzle exit as the hydrogen ejector's. And this air ejector is tested while the humidity of the secondary flow is varied.

• Food Science and Preservation
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• v.1 no.1
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• pp.37-43
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• 1994

A microcomputer system consisting of 16-bit microcomputer, PCL-711S interface board, censors, and converters have been set up in order to automatically measure temperature, humidity and weight loss which are major variables of storage of apple. This system was operated by PC-LabDAS software. It has been possible to measure continuously the weight loss of Fuji apple stored in CA with the weight converter made by a miniature load cell and a strain amplifier. The temperature was checked by a k-type thermocouple and Pt 100 $\Omega$ RTD, and humidity by PQ653JAl humidity sensor. It has been possible to set up a linear equation which showers high correlationship between the estimate of temperature, weight humidity and the output of the converter in that r2 is more than 0.99. Transpiration rate, a significant factor of quality deterioration for CA storage of apple, can be estimated with these values.

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.412-424
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• 2015

Objectives: An ultra dry air environment of nearly ${\leq}2%$ RH is often required in lithium battery factories. The objective of this study is to evaluate the subjective eye, pulmonary, nose, and skin symptoms of workers exposed to ultra-low relative humidity and thionyl chloride. Methods: We recruited 274 workers using a self-reported questionnaire in March 2014. Those who worked in ultra-low relative humidity and with thionyl chloride were identified and their prevalence of symptoms was compared with that of other workers. We excluded white collar workers, researchers and other workers who were exposed to various hazard factors, and finally included 164 workers. Results: There were significant differences in the rate of self-reported eye and skin symptoms between exposure group_1 and exposure group_2. Exposure group_2 experienced more frequent eye, and skin symptoms. Multinomial logistic regression analysis for experience of dry eye symptoms and skin symptoms in exposure group_2 showed that dry eye symptoms (odds ratio [OR], 6.33, 95% confidence interval [CI], 2.19-18.24, p<0.001), and itchiness (OR, 6.45, 95% CI, 1.94-21.43, p<0.01) were the significant variables. The complaints of workers experiencing ultra-low relative humidity and thionyl chloride were high compared with other workers. Conclusion: These findings suggest that exposure to ultra-low relative humidity and thionyl chloride may be associated with more frequent eye and skin symptoms than exposure to ultra-low relative humidity alone. The current precautions to protect workers from the adverse effects of ultra-low relative humidity and thionyl chloride appear to be insufficient, indicating that additional management plans to reduce symptoms should be considered.