• Fashion & Textile Research Journal
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• v.25 no.1
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• pp.119-126
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• 2023

This study aimed to determine the effects of relative humidity and fiber properties on the moisture permeability of multilayer systems by measuring water vapor transmission in the overlapping condition of various fabrics. The results confirmed that the property of the fabric in contact with the humid environment affects the moisture permeability. If the layer facing the humid environment is hydrophobic and the layer facing the dry environment is superhydrophobic, water vapor transmission increases by up to 17.8% compared to the opposite conditions. Comparing the correction values of the water vapor transmission reflecting the thickness of the specimen under the multilayer condition showed that permeability was higher when the hydrophilic or hydrophobic layer was facing the humid environment. The opposite was true from the "push-pull" effect of absorption mechanism. In the case of moisture permeability, the more hydrophilic the surface facing the humid environment, the more permeable that water vapor diffuses and passes through. It was concluded that the "pull-push" effect, in which water vapor diffuses widely through the hydrophilic facing a humid environment and then passes through the hydrophobic layer, contributes to the improvement of permeability. Permeability differed according to the multilayer overlapping condition. When the relative humidity was high, the "pull-push" effect was insignificant. This is caused by water droplets absorption after the partial migration of water due to condensation. These results suggest that the overlapping conditions and properties of fabrics should vary depending on heavy sweating or not.

• Journal of the Ergonomics Society of Korea
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• v.17 no.3
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• pp.41-59
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• 1998

Thermal comfort aspect of a locally-cooled target space in warm and humid environments(typically in the rainy summer season) was studied in view of PPD index. First. theoretical analyses were conducted to examine the effect of the governing parameters(such as air temperature, relative humidity and air velocity, etc.) using a computer model. Secondly, experimental investigations were also performed in a climatic room designed to simulate corresponding thermal conditions of outdoor environments. During the tests, temporal variation of PPD was recorded as functions of climatic variables(outdoor and indoor temperatures, relative humidity and air velocity) for the given human factors(metabolic heat generation and clothing). From both theoretical and experimental investigations, air temperature and air velocity were found to be the most dominant parameters affecting PPD of the target space. Results were summarized as: 1. Relative humidity of the locally-cooled target space tends to approach that of outdoor's as the space is subjected to an ON-OFF mode of cooling, since moisture potential of the two rooms reaches an equalized state as a result of moisture diffusion. 2. It was recognized that changes in relative humidity did not show any significance in view of thermal comfort as was reported in the previous studies, while variations of both temperature and air velocity caused relatively large changes in the degree of thermal comfort. 3. In-door environment should be evaluated in terms of PPD instead of relative humidity commonly recognized as an important climatic variable particularly in warm and humid environments.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.57.1-57.1
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• 2011

The effects of relative humidity on the properties of the porous $ZrO_2$ ceramics were investigated in terms of the curing behavior of phenolic resin as a binder. The $ZrO_2$ powders containing 5wt% of phenolic resin were conditioned in a consistent chamber condition at a temperature of $50^{\circ}C$ and different humidity levels (25, 50, 75, and 95%) for 1 h. The exposure of humid atmosphere caused changes of density and microstructure in the green bodies. The higher level the powders were exposed to the humid atmosphere, the lower green density was obtained and the more irregular microstructure was observed due to aggregation by the curing of phenolic resin. After firing, the porosity of specimens has risen from 35.7% to 38.1% and Young's modulus has declined in response to the variation of green density. These results could be explained by the degree of resin cure which was associated with the area under the exothermic peak enclosed by a baseline of DSC thermogram curve. Also, the curing behavior of phenolic resin according to relative humidity has been confirmed by decrease of ether groups which have interacted with the phenolic-OH group and the hexamine as a curing agent. Consequently, it could be demonstrated that increase the relative humidity during fabrication of porous $ZrO_2$ diminished the compaction and properties of specimens after firing owing to curing of phenolic resin.

• The Korean Journal of Ecology
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• v.24 no.4
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• pp.227-232
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• 2001

The biomass structure for three major components viz., the dominant grass, Chrysopogon zeylanicus Thw., the 'other grasses' and the'remaining species'and dry matter dynamics for total community were studied over a period of one year in an annual fire influenced subtropical humid grassland community in Western Ghats, India. The biomass of aboveground, belowground and litter compartments were high as in other humid grasslands and generally have positive correlation with rainfall, rainy days and relative humidity with the exception of litter parts. The above and belowground net primary productions (4,561 and 722 g/㎡, respectively) were also higher and were comparable with other humid tropical grasslands. The turnover of organic matter was rapid, Of the total input of 14.47 g/㎡ into the system, about 86.3% was allocated to above ground parts and 13.7% to below ground parts. The total disappearance was 2.56 g/㎡ and it was accounted to be 17.68% of the total output. The net surplus of dry matter (82.32%) in the post fire community indicates that the grassland was maintained in a seral stage. Hence it is suggested that prescribed burning may keep this ecosystem in a highly productive and seral stage.

• Journal of The Korean Society of Agricultural Engineers
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• v.49 no.2
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• pp.87-97
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• 2007

The aim of this study was to compare crop contamination between two irrigation methods using microbial-contaminated water. The effect of relative humidity on microbial survival of the three indicator microorganisms was also investigated. Escherichia coli ATCC 25922, Clostridium perfringens ATCC 3624, and coliphage PRD1 were applied to irrigation water to grow cantaloupe, lettuce, and bell pepper. Half of the sixteen plots were subsurface drip irrigated (SDI) and the other half were furrow irrigated (FI). Two relative humidity levels were controlled at 15-65 % and 55-80 % for the dry and humid condition experiments, respectively. Samples of produce, surface soil, and subsurface soil at a depth of 10 cm were collected over a two-week period following the application of the study microorganisms. Overall, greater contamination of both produce and soil occurred in the FI plots. For the SDI plots, preferential water paths and resulting water appearance on the seed beds seemed to be responsible for produce contamination. Relative humidity levels did not appear to affect microbial survival in soil. PRD 1 showed lower inactivation rates than 5. coli in both dry and humid conditions. C. perfringens did not experience significant inactivation over the experimental period, suggesting this microorganism can be an effective indicator of fecal contamination.

• Korean Journal of Materials Research
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• v.5 no.6
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• pp.715-722
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• 1995

Vinylbenzyl triphenyl phosphonium chloride (VTPC) was prepared for the humid membrane. The humidity sensitive memo)lane was composed of copolymers, which have differnet content of VTPC and styrene (VTPC : ST=1 : 0.7 : 3, 5 : 5, 3 : 7). The changes in electrical properties of copolymers with relative humidity were measured. It was found that the impedance decreased with an increase of the content of VTPC in the humid membrane, and the Impedance also decreased with an increase of thickness of humid membrane. The copolymer derived from same equip of VTPC and ST showed 12M$\Omega$-100M$\Omega$ at 70%RH-90%RH, which was required for the current humidity sensor operating at high humidity or dew point. The temperature dependence coefficient at a temperature range 15$^{\circ}C$∼35$^{\circ}C$ was found to be -0.5%RH/$^{\circ}C$ and the hysterisis fabled within the range ${\pm}$2%RH. The response time was found to be 40seconds for varing relative humidity from 75% RH to 95%RH and vice versa.

• Water Engineering Research
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• v.5 no.4
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• pp.185-193
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• 2004

Estimates of annual actual evapotranspiration are needed in water balance studies, water resources management projects, and many different types of hydrologic studies. This study validated a set of 5 empirical equations of estimating annual actual evapotranspiration with climate data on 11 watersheds, and evaluated the further applicability of these forms in estimating annual runoff on watershed level. Five empirical equations generally overestimated annual evapotranspiration, with relative errors ranging $3.3\%$ to $47.2\%$. The results show that Schreiber formula can be applicable in determining annual evapotranspiration in sub-humid region that is classified by aridity index, while Zhang equation gave better results than the remaining methods in humid region. The mean differences for annual evapotranspiration bias over 11 watersheds are Zhang, Schreiber, Budyko, Pike, and Ol'dekop formula from lowest to highest. The empirical equations provide a practical tool to help water resources managers in estimating regional water resources on ungauged large watershed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.397-407
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• 2004

It is well known that some key parameters, such as evaporating temperature, refrigerant mass flow rate, face velocity and inlet air temperature, have significant influence on the evaporator performance. However performance studies related to a humid environment have been very scarce. It is demonstrated that the refrigerant mass flow rate, heat flux, water condensing rate and air outlet temperature of the evaporator significantly increase with air inlet relative humidity. As the air inlet relative humidity increases, the latent and total heat transfer rates increase, but the sensible heat transfer rate decreases. The purpose of this study is to provide experimental data on the effect of air inlet relative humidity on the air and refrigerant side pressure drop characteristics for a slit fin-tube heat exchanger. Experiments were carried out under the conditions of inlet refrigerant saturation temperature of 7 $^{\circ}C$ and mass flux varied from 150 to 250 kg/$m^2$s. The condition of air was dry bulb temperature of 27$^{\circ}C$, air Velocity Varied from 0.38 to 1.6 m/s. Experiments Showed that air Velocity decreased 8.7% on 50% of relative humidity 40% of that at degree of superheat of 5$^{\circ}C$, which resulted that pressure drop of air and refrigerant was decreased 20.8 and 8.3% for 50% of relative humidity as compared to 40%, respectively.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.4
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• pp.381-388
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• 1998

Hot and humid weather in summer generally brings about discomfort. Experiments on which relative humidity makes effects on the comfort sensation were performed to the young and the aged using sensation vote. From July to October 1996, seven college students and eleven aged people were exposed for 2 hours under six different conditions in the Pukyong National University test chamber so as to determine the effects of relative humidity on thermal and comfort sensations. Subjects were wearing same clothes, and the mean clo value was 0.5. The mean radiant temperature was equal to the air temperature and air velocity in the occupied zone around 0.lm/s. In the experiments, it was found that discomfort could be largely reduced when the humidity is controlled to low values in the settled high temperature.

• International Journal of Air-Conditioning and Refrigeration
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• v.9 no.1
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• pp.65-70
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• 2001

During the summer season, it is very hot and humid in Korea. So the humidity is an important factor regarding the environmental control function of building envelops. The purpose of this research is to measure and analyze the characteristics of such environmental factors as relative humidity, dry bulb temperature and air velocity varies both in the clay and cement envelop structures using granite dome models during the summer time. The interior relative humidity of the clay model is constant regardless of exterior humidity although a little range of variation is shown in comparison to the cement model.