• Korean Journal of Soil Science and Fertilizer
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• v.46 no.1
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• pp.32-39
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• 2013

The relationship between relative water contents of lettuce leaves and biochemical activities in lettuce was examined in this study to explore an adaptation response of lettuce to water stress from soils. Soil water contents and relative water contents of leaves were positively related to show $R^2$=0.8728. Hydrogen peroxide contents of leaves rapidly increased with reduction of soil water content, whereas soluble protein contents and dry matters rapidly decreased. And chlorophyll a and b contents of leaves decreased with increase in carotenoid content. Furthermore, the activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR) increased dramatically, and mRNA transcript levels of APX, MDHAR and DHAR also increased. Relationship of relative water content of lettuce leaves to hydrogen peroxide, to ascorbate peroxidase activity, to dehydroascorbate reductase activity, and to monodehydroascorbate reductase activity was shown to be positively correlated. It is highly plausible from this study that these enzyme activities could be developed as an indicator of water states in soils.

• 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.

• Particle and aerosol research
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• v.9 no.4
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• pp.247-252
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• 2013

Removal of water contents in a gas is needed in industrial field of gas processing related on energy production/conversion, and environmental treatment. Inertial separators are economic devices for separating droplets from the gas stream. For design and incorporation of inertial pre-treatment separator, characteristics of removal of water contents with various operation conditions are needed. In this study, removal efficiency of water droplets at various flowrates (5-14 SCMM) and relative humidity (R.H.) conditions (40%, and 90%) has been investigated. At low R.H. condition, the removal characteristic is similar to the removal of solid particles. But, droplet growth resulting from the condensation of water vapor at high R.H. condition, is significant and it made increase in removal efficiency of droplet phase of water contents. For rapid removal of water contents, an effective method to enhancing condensation growth of water droplets is highly needed.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2009.05a
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• pp.348-351
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• 2009

In order to evaluate the performance of a grounding system against lightning or fault currents including high frequency components, the grounding impedance should be considered rather than its ground resistance. Recently, some researches on the evaluation and modeling of the grounding impedances have been carried out but the results have not been yet sufficient. This paper deals with the frequency dependence of the resistivity and relative dielectric constant of sand associated with water contents. As a result, the resistivity of sand is getting lower with increasing water content and it is nearly independent on the frequency in the range of less than 1MHz, and is decreased over the frequency range of above 1MHz. Also, the relative dielectric constant is rapidly decreased with the frequency in the range of less than 10kHz, but it is nearly not dependent on the frequency over the frequency range of 10kHz. It was found from this work that the frequency dependance of resistivity and relative dielectric constant of soil should be considered in designing the grounding systems for protection against lightning or surges.

• Journal of the Korean GEO-environmental Society
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• v.12 no.2
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• pp.23-33
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• 2011

In this paper, we got soil-water characteristic curve(SWCC) of Nak-Dong River's sand respectively as relative density 40%, 60%, 80% and content of silt 0%, 10%, 20%, 30%. As a result, the more the sand densify in the same silt content and the more the sand has silt in the same relative density, the change of volume water content was decreased. we have known effect of silt contents for SWCC and verified existing empirical formula of SWCC. As experiment results of soil-water characteristic curves compared to the empirical solutions, the results of van Genuchten(1980) and Fredlund & Xing(1994) were well-matched showing S type curves with experiment results. Especially the empirical solution of Fredlund & Xing showed almost same results of the coefficient of correlation($R^2$) equal to 0.99.

• 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.

• The Korean Journal of Malacology
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• v.20 no.1
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• pp.27-34
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• 2004

Based on both field and laboratory experiments, seasonal changes in the species composition and abundance of phytoplankton in the gut contents of the jedo venus clam, Protothaca jedoensis, and its feeding selectivity were investigated. The phytoplankton in the gut contents comprised Bacillariophyceae (diatom), Chlorophyceae, Chrysophyceae, and Dinophyceae, of which the diatoms being the most predominant throughout the year. Although the number of species and the abundance of phytoplankton in the sea water were always more diverse and more abundant than in the gut contents, the relative number and abundance were generally similar in the seawater and in the gut contents. In the laboratory experiments, the relative abundances of Coscinodiscus marginatus and Thalassirosira eccentrica were much more higher in the gut contents than any other algal species, while Paralia sulcata, Skeletonema costatum, and Eucampia zodiacus were abundant in order of cell density in the ambient water. These results suggest that P. jedoensis may feed preferably on single algal cell or smaller chains of algal cells.

• Journal of Bio-Environment Control
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• v.26 no.2
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• pp.146-150
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• 2017

This research investigated the effect of photo/dark period and relative humidity during dark period on the growth and quality of water dropwort in a closed-type plant factory system. At 30 days after planting, the shoot fresh weight of water dropwort under relative humidity of 60/90%(light/dark) treatment significantly higher than that under relative humidity of 60/60% treatment. The shoot fresh weight of water dropwort increased by extending light period under relative humidity of 60/60% treatment, but 16/8h photo/dark period showed the best shoot fresh weight, followed by 20/4h and 22/2h under relative humidity of 60/90% treatment. In the relative humidity of 60/90% treatment, the tipburn occurrence was reduced under 16/8h photo/dark period condition as 1.4%, whereas it was significantly increased under 20/4h and 22/2h of relatively long light time duration as 15.5% and 30.3%, respectively. In the relative humidity of 60/60% treatment, the tipburn occurrence was 15.5% under 16/8h photo/dark period condition and those under 20/4h and 22/2h photo/dark period condition were higher than 25%. The stem hardness of water dropwort was lowest in relative humidity of 60/90% and 16/8h photo/dark period treatment. The mineral contents of leaves were decreased by extending light period, but the contents of Ca were not different significantly among the treatments except the 60/60% and 22/2h treatment.

• Journal of Ecology and Environment
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• v.36 no.4
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• pp.255-265
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• 2013

This study was conducted to determine the extent of drought resistance based on physiological responses of Calystegia soldanella under water deficit. In order to investigate the changes of plant growth, stomatal density, photosynthesis, chlorophyll fluorescence, the contents of chlorophyll and carotenoid, osmolality, total ion contents, the contents of carbohydrate and proline, C. soldanella was grown under well watered and drought stressed conditions for 12 days. In this study, water-deficit resulted in remarkable growth inhibition of C. soldanella. The effect of water-deficit on plant growth was associated with low osmotic potential of soil. On day 12 after drought treatment, dry weight, relative water contents, number and area of leaves and stem length were lower than those of control. The stomatal conductance and net photosynthetic rate were significantly reduced in water stressed plant to regulate inner water contents and $CO_2$ exchange through the stomatal pore. Chlorophyll fluorescence and chlorophyll contents were not different in comparison with the control, indicating that the efficiency of photosystem II was not affected by drought stress. This results could be explained that water-deficit in C. soldanella limits the photosynthetic rate and reduces the plant's ability to convert energy to biomass. A significant increase in total ion contents and osmolality was observed on day 7 and day 12. Accumulation of proline in leaves is associated with the osmotic adjustment in C. soldanella to soil water-deficit. Consequently, this increase in osmolality in water stressed plant can be a result in the increase of ion contents and proline.

• Korean Journal of Food Science and Technology
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• v.37 no.6
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• pp.1028-1034
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• 2005

Effects of temperature and relative humidity on contents of water-soluble vitamins (vitamins $B_1,\;B_2,\;B_3,\;B_6$, and C) of two commercial tablets ("Multivitamin Dandelion" and "Chewable vitamin C") were investigated. When stored at various temperatures (25, 35, and $45^{\circ}C$) with cap, all measured vitamins were stable and degraded very slowly during 24 weeks of storage; low relative humidity (11% RH) without cap also provided stability during storage period. At higher relative humidities (75 and 100% RH), contents of all water-soluble vitamins, except vitamins $B_2\;and\;B_3$, decreased significantly at early storage period. These results showed that stability of water-soluble vitamins is highly dependent on relative humidity rather than storage temperature.