• Korean Journal of Medicinal Crop Science
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• v.3 no.2
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• pp.81-83
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• 1995

This study was conducted to know the effect of soil moisture content on growth of aerial parts and root of Valeriana fauriei var. dayscarpa HARA in pot condition. The soil moisture contents were 30, 45, 55, 70, 80 and 90% of maximum water requirement. The result obtained are as follows; 1. Width and length of leaves in valerian were slightly increased with increase the soil moisture content, however, length of petiole and root were increased with soil moisture content up to 80%. 2. It showed the positive correlations between moisture content and root weight and extract content in root. 3. Optimum soil moisture content was 80 to 90% of maximum water requirement.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.5
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• pp.93-103
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• 2020

In this study, we estimated soil moisture values using the Deep Neural Network(DNN) scheme at the mountainous regions. In order to test the sensitive analysis of DNN scheme, we collected the measured(at the soil depths of 10 cm and 30 cm) soil moisture and DNN input(weather and land surface) data at the Pyeongchang-gun(relatively flat) and Geochang-gun(steep slope) sites. Our findings indicated that the soil moisture estimates were sensitive to the weather variables(5 days-averaged rainfall, 5 days precedent rainfall, accumlated rainfall) and DEM. These findings showed that the DEM and weather variables play the key role in the processes of soil water flow at the mountainous regions. We estimated the soil moisture values at the soil depths of 10 cm and 30 cm using DNN at two study sites under different climate-landsurface conditions. The estimated soil moisture(R: 0.890 and RMSE: 0.041) values at the soil depth of 10 cm were comparable with the measured data in Pyeongchang-gun site while the soil moisture estimates(R: 0.843 and RMSE: 0.048) at the soil depth of 30 cm were relatively biased. The DNN-based soil moisture values(R: 0.997/0.995 and RMSE: 0.014/0.006) at the soil depth of 10 cm/30 cm matched well with the measured data in Geochang-gun site. Although uncertainties exist in the results, our findings indicated that the DNN-based soil moisture estimation scheme demonstrated the good performance in estimating soil moisture values using weather and land surface information at the monitoring sites. Our proposed scheme can be useful for efficient land surface management in various areas such as agriculture, forest hydrology, etc.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.173-183
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• 2015

The aim of this study was to develop a soil moisture simulation model equipped with meteorological data enhanced by WRF (Weather Research and Forecast) model, and this soil moisture model was applied for quantifying soil moisture content and irrigation requirement. The WRF model can provide grid based meteorological data at various resolutions. For applicability assessment, comparative analyses were conducted using WRF data and weather data obtained from weather station located close to test bed. Water balance of each upland grid was assessed for soils represented with four layers. The soil moisture contents simulated using the soil moisture model were compared with observed data to evaluate the capacity of the model qualitatively and quantitatively with performance statistics such as correlation coefficient (R), coefficient of determination (R2) and root mean squared error (RMSE). As a result, R is 0.76, $R^2$ is 0.58 and RMSE 5.45 mm in soil layer 1 and R 0.61, $R^2$ 0.37 and RMSE 6.73 mm in soil layer 2 and R 0.52, $R^2$ 0.27 and RMSE 8.64 mm in soil layer 3 and R 0.68, $R^2$ 0.45 and RMSE 5.29 mm in soil layer 4. The estimated soil moisture contents and irrigation requirements of each soil layer showed spatiotemporally varied distributions depending on weather and soil texture data incorporated. The estimated soil moisture contents using weather station data showed uniform distribution about all grids. However the estimated soil moisture contents from WRF data showed spatially varied distribution. Also, the estimated irrigation requirements applied WRF data showed spatial variabilities reflecting regional differences of weather conditions.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.3
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• pp.4171-4183
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• 1976

This study is to investigate the effect of some physical properties of soil on the compaction. The compaction effect depends upon various factors such as soil type, moisture content, gradation and compaction energy. In this study, with steady compaction energy, the relationships between maximum dry density and moisture content, gradation and consistency were analyzed by soil types. Some results obtained in this study are summarized as follows 1. Generally, the coarser the grain size, the bigger is the maximum dry density and the smaller is the optimum moisture content and its moisture-dry denisty curve is relatively steep. The finner the grain size, the smaller is the max. dry density and the bigger is the opt. moisture content and its moisture-dry density curve is less steep. 2. The relationship between max. dry density (${\gamma}$dmax) and opt. moisture content, void ratio, clay content, percent passing of No. 200 sieve, liquid limit and plastic limit can be represented by the equation ${\gamma}$dmax =ao+a1X(a0>0, a1<0) 3. The relationship between opt. moisture content (Wopt) and clay content, percent passing of No. 200 sieve, liquid limit and plastic limit can be represented by the equation Wopt=a0+a1X(a0>0, al>0). 4. The fact that maximum dry density of the compacted soil is decreased with the increase of the optimum moisture content in any types of soil tested, and the fact that optimum moisture content can be positively correlated with clay content, percent passing of No. 200 sieve, liquid limit and plastic limit of the soil, lead to the conclusion that clay content, percent passing of No. 200 sieve, liquid limit and plastic limit of the soil are direct factors in reduction of the maximum dry density of engineering soil.

• Journal of Forest and Environmental Science
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• v.38 no.4
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• pp.229-238
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• 2022

Q. mongolica and Q. dentata are representative species of deciduous forest communities in Korea and are known to be relatively resistant to soil drying condition among Korean oaks. This study attempted to elucidate the degree of competition and ecological niche characteristics of the two species by comparing the ecological responses of the two species according to soil moisture. Competition between Q. mongolica and Q. dentata was shown to be more intense under the conditions where moisture content was low than under the conditions where moisture content was high. As for the ecological niche overlaps of the two species for soil moisture, the structural traits of plant such as stem diameter overlapped the most, the traits of biomass such as petiole weight overlapped the least, and photosynthetic organ-related traits such as leaf width and length overlapped intermediately. When looking at the competition for soil moisture between the two species, it can be seen that Q. mongolica won in nine traits (leaf width length, leaf lamina length, leaf lamina weight, leaf petiole weight, leaf area, leaves weight, shoot weight, root weight, and plant weight) and Q. dentata won in the remaining seven traits (leaf petiole length, leaves number, stem length, stem diameter, stem weight, shoot length, and root length). Competition between the two species for the moisture environment of the soil was shown to be intense under the conditions where moisture content was low. The degree of competition between Q. dentata and Q. mongolica for soil moisture is high under the conditions where soil moisture content is low, and it is judged that Q. mongolica is more competitive for soil moisture than Q. dentata.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.123-131
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• 1994

Experimental studies were conducted to make clear the soil moisture environment under the condition of paddy-upland rotational fields by investigating water-table depths and soil moisture contents during growing season of crops in two kinds of soil. The following results were obtained. 1.Although water-table depths fluctuated with the amount of rainfall in the experimental field, it seemed that the variation of vater4able depths in the paddy-upland rotational, field was strongly affected by the condition of locations on paddy fields. 2.It is recognized that the concept of sum of excess water depth(SEWxx) and sum of excess water day(SEDxx) can be used to represent the soil moisture stress index due to the fluctuation of water-table depths. 3.The results of this study clearly indicate that drainage in paddy-upland rotational field to maintain an optimum soil moisture content must be made by introducing the concept of block drainage which needs both subsurface drainage and intercept drainage around a field. 4.Soil moisture contents were affected by both the amount of rainfall and water-table depths, however, the moisture content for top soil showed higher correlation with the amount of rainfall while that for subsoil with water-table depths.

• Korean Journal of Plant Resources
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• v.35 no.6
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• pp.762-769
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• 2022

Growth characters and ingredient contents of two-year-old bellflower (Platycodon grandiflorum) roots were investigated under both control and soil moisture treatment condition using soil moisture control system including soil sensing and automatic water supply chain in this study. Root diameter, fine root number, root length, fresh weight and dry weight of the plant were significantly influenced by the automatic water treatment, 20%, 30%, 40% and 50%, respectively. Ingredient contents of the two-year-old roots in bellflower plants were detected in the 20% and 50% of controlled soil moisture content. Contents of amino acids were decreased by the soil moisture treatment, meanwhile, contents of minerals were not showed significant decrease except for phosphorus content. Showing no difference in proline and tyrosine, fourteen of the amino acid contents were gradually decreased by the increased soil moisture contents, with significant decrease in serine, glycine, alanine, leucine, lysine and histidine at 20% treatment.

• Water Engineering Research
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• v.5 no.1
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• pp.1-16
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• 2004

The purpose of this study is to understand the characteristics of hourly PET(Potential Evapo Transpiration) variation estimated using Penman ET model. The estimated PET using Penman model was compared with measured ET. For this study, two subwatersheds were selected, and fluxes, meteorological data and soil moisture data were measured during the summer and winter days. During the winter days, the aerodynamic term of Penman ET is much greater than that of energy term of Penman ET for dry soil condition. The opposite phenomena appeared fer wet soil condition. During the summer days, energy term is much more important factor for ET estimation compared with aerodynamic term regardless of soil moisture condition. Penman ET, measured ET, and energy term show the similar hourly variation pattern mainly because the influence of net radiation on the estimation of Penman ET is much more significant compared with other variables. Even though there are much more soil moisture in the soil during the wet days, the estimated hourly ET from Penman model and measured hourly ET have smaller values compared with those of dry days, indicating the effect of cloudy weather condition.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.4
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• pp.61-71
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• 2015

Quantitative variability of AMSR2 (Advanced Microwave Scanning Radiometer 2) soil moisture data shows that the remotely sensed soil moisture is underestimated during Spring and Winter seasons and is overestimated during Summer and Fall seasons. Therefore the bias correction of the remotely sensed data is essential for the purpose of water resource management. To enhance their applicability, the bias of AMSR2 soil moisture data was corrected using ground observation data at Cheorwon Chuncheon, Suwon, Cheongju, Jeonju, and Jinju sites. Test statistics demonstrated that the correlation coefficient R is improved from 0.107~0.328 to 0.286~0.559 and RMSE is improved from 9.46~14.36 % to 5.38~9.62 %. Bias correction using ground network data improved the applicability of remotely sensed soil moisture data.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.6
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• pp.68-74
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• 2014

The electrical parameters of soils are highly dependent on the various factors such as types of soil, chemical compositions, moisture content, temperature, frequency, and so on. The analysis of soil parameters is of fundamental importance in design of grounding systems. In this paper, we present the experimental results of frequency-dependent impedance, resistivity, permittivity of soils as functions of types of soil and moisture content. The impedance and resistivity of soils are decreased as the moisture content and the frequency increase. In particular, the variation of the soil resistivity with the frequency is pronounced in the conditions of high resistivity and low moisture content. On the contrary, the permittivity of soils are sharply decreased with increasing the frequency below 10kHz and the frequency-dependent permittivity of soils are highly changed in the conditions of high moisture and low resistivity.