• Journal of the Korean Wood Science and Technology
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• v.44 no.2
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• pp.283-293
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• 2016

Owing to an increase in the air tightness of recent buildings, the natural ventilation rate was significantly lowered and the removal of accumulated moisture became difficult in these buildings. The hygrothermal performance of these buildings should be carefully considered to provide comfortable indoor environment by removing the moisture condensation risk and the mold growth potential. In this study, hygrothermal performance of two selected wall structures was investigated based on WUFI simulation program. The results displayed that the indoor temperature had impact on the moisture accumulation in the insulation layer for both modeled walls, showing that lower indoor temperature resulted in higher moisture accumulation, especially in the wood frame structure. Also, the yearly moisture accumulation profile exhibited a downward shift throughout the year by adding a vapour retarder with a lower sd-value. In addition, both of the two walls have condensation risk in winter, due to low temperature level. The wood frame structure has a bigger fluctuation and higher condensation risk than the concrete structure.

• Journal of Environmental Science International
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• v.31 no.1
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• pp.43-50
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• 2022

In this paper, lysimeter was installed to analyze the moisture fluctuations on the surface of a forest. The weight of the soil was measured, and the moisture fluctuations were calculated through the difference in weight over time. The amount of dew condensation on the surface of the ground was about 2-7 mm. January experienced the most dew condensation (7.2 mm). It was found that about 43 mm of dew condensation was generated over one year. To analyze the characteristics of evapotranspiration in the forest, the evapotranspiration on the surface was measured by the lysimeter method and the evapotranspiration on the upper part of the canopy was measured by the eddy covariance method. These results were compared and analyzed. Until mid-October, the evapotranspiration of the forest was active, and the amount of evapotranspiration on the top of the canopy was higher than the amount on the surface. Thereafter, the amount of evapotranspiration on the top of the canopy decreased due to the lowering of temperature and net-radiation. The amount of evapotranspiration on the surface and above the canopy showed the same tendency.

• Journal of the Korean Wood Science and Technology
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• v.34 no.2
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• pp.22-29
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• 2006

On purpose to reduce accumulated moisture and to prevent moisture condensation in a light-frame wall, thermal characteristics and moisture behaviors were investigated for four different wall assemblies; a) typical wall, b) addition of vapor retarder between the insulation and the gypsum board, c) addition of air gap for natural ventilation behind the siding, d) composition with b) and c). Each wall was tested under two climate conditions; 1) $20^{\circ}C$, 50% RH (indoor) and $30^{\circ}C$, 85% RH (outdoor), 2) $30^{\circ}C$, 85% RH (indoor) and $20^{\circ}C$, 50% RH (outdoor).The results showed that the typical wall assembly had poor resistance against moisture intrusion from the inside of building. Outdoor and indoor humidity caused the moisture condensations on the inside of the siding and the back surface of the sheathing respectively. The addition of a vapor retarder did not give significant improvement in preventing the moisture intrusion.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.17-18
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• 2012

Moisture condensation leading to defects that occur repeatedly in the winter, and recognize the same method, the problem of the other buildings in the same area again and again, a vicious cycle that occurs due to the temporary lack of systematic research and processing way of coping has been recurring. In this study, as warming progresses, more inside the air-conditioned summer season due to an increase in the ambient temperature of the condensation phenomenon to happen about summer wall condensation phenomena are expected to analyze the case of a building to prevent condensation and for insulation designs are proposed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2008.11a
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• pp.341-344
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• 2008

Numerical simulations have been carried out for a supersonic two-dimensional flow over open, rectangular cavities (length-to-depth ratios are L/D = 1.0) in order to investigate the effect of non-equilibrium condensation of moist air on supersonic flows around the cavity for the flow Mach number 1.83 at the cavity entrance. In the present computational investigation, a condensing flow was produced by an expansion of moist air in a Laval nozzle. The results obtained showed that in the case with non-equilibrium condensation for L/D = 1.0, amplitudes of oscillation in the cavity became smaller than those without the non-equilibrium condensation. Furthermore, the occurrence of the non-equilibrium condensation reduced the peaks of power spectrum density and the frequency of the flow field oscillation increased in comparison with the case of $S_0$ = 0.

• The Korean Journal of Mycology
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• v.40 no.4
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• pp.215-223
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• 2012

This study was aimed to find factors responsible for export potential of oyster mushroom through postharvest treatments including high pressure $CO_2$ and anti-moisture pad. Temperature fluctuation during export simulation induced the condensation of excess moisture resulting in the quality loss due to browning and decay. Anti-moisture pad was effective on inhibition of browning occurrence in part. High temperature exposure ($15^{\circ}C$) as retail simulation greatly offset the positive effect of anti-moisture pad. Short term treatment of high pressure $CO_2$ delayed the surface color changes as hunter L, a, and b values. There was no consistent tendency in total sugar and phenolics between treatments. In general, the export potential of small size mush-room (export size) at harvest was higher than large ones (domestic size). The major factors asso-ciated with the quality decrease of oyster mushroom during export were moisture condensation in packages and temperature fluctuation. Further research is required to improve mushroom export procedures.

• Elastomers and Composites
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• v.26 no.2
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• pp.115-122
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• 1991

Polychloroprene rubber was moisture-cured after treating them with silane coupling agents such as 3-mercaptopropyltrimethoxysilane(MPS), 3-methacryloxypropyltrimethoxysilane(MAS) and vinyltriethoxysilane(VES), especially MPS. The cure reaction is composed of two steps. The first is the reaction between chlorine atoms of CR and silane coupling agents. The second is the formation of cross-links which are siloxane linkage. The linkage is formed by the condensation of silanol groups which are produced by the hydrolysis of alkoxysilyl groups. The first reaction was kinetically studied and the reactivity of CR to silane coupling agents was determined in previous literature. Crosslinking density and mechanical properties of the moisture-cured elastomer filled with silica or non-filled were studied and the feasibility of this cure system was discussed.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.36 no.3
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• pp.169-176
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• 2020

The authors developed a nodal network model that simulates the flow of moist air and the thermal behavior of a target area. The nodal network model was enhanced using a parameter estimation technique based on the measured temperature, humidity, and schedule data. However, the nodal model is not good enough for predicting humidity of the target space, having 55.6% of CVRMSE. It is because re-evaporation effect could not be modeled due to uncertain factors in the field measurement. Hence, a data-driven model was introduced using an artificial neural network (ANN). It was found that the data-driven model is suitable for predicting the condensation compared to the nodal model satisfying ASHRAE Guideline with 3.36% of CVRMSE for temprature, relative humidity, and surface temperature on average. The model will be embedded in automated devices for real-time predictive control, to minimize the risk of surface condensation at dressroom in an apartment housing.

• Journal of the Korean Wood Science and Technology
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• v.44 no.1
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• pp.75-84
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• 2016

Thermal performance of wooden houses used by building materials effectively contributing to building energy saving has been improved. However, the performance was decreased to the condensation and mould growth from exterior wall because the moisture control was difficult to high insulation and airtightness. Therefore, the hygrothermal performance of exterior wall, that selected 5 types of wooden houses, evaluated using the hygrothermal simulation program: heat and moisture behavior, condensation and mould growth risk. Wooden houses were selected Rural houses standard plans '10 and '14, $2^{{\prime}{\prime}}{\times}6^{{\prime}{\prime}}$ type, EIFS and wood-based passive house. And the wall A, B, C, D and E were determined by layer component of each wall. The U-value of exterior wall are 0.171, 0.172, 0.221, 0.150, $0.079W/m^2K$. The OSB absolute water content of the wall A and C was exceeds the reference value of 20%, and it was confirmed that condensation occur at insulation material inner surface through the condensation evaluation in the winter. The wall D and E showed excellent results with condensation and water content evaluation compared to others. However, mould growth risk assessment in all five types of wall had have risk. We were determined that hygrothermal performance difference of exterior wall occur the difference in the layer structure rather than in thermal performance.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2004.11a
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• pp.130-136
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• 2004

Presence of water in the lubricating oils could be one of the first indicators of potentially expensive and possibly catastrophic failure of the machine as it may cause displace the oil films to prevent the lubrication function of the oil or chemically react with many oil additives resulting in the oil degradation. In order to detect water content quantitatively in lubricating oils many methods and sensors has been developed. Among these, capacitive sensors including sensitive layer, whose dielectric factor changes according to the water content absorbed in the layer, are proposed mainly in the market. But these sensors are not sensitive to a high water content. Besides, the absorbing layer soils in time. In this work, an evaporation of water moisture from oil into air volume above lubricant surface and condensation of water vapor at a cooling surface was used to measure water content quantitatively in an lubricating oil. Laboratory test results of a prototype sensor were presented. Test results showed that the proposed method could be avaliable to measure a low levels of oil moisture.