• International Journal of Industrial Entomology and Biomaterials
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• v.7 no.1
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• pp.45-49
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• 2003

Foliar treatment with different concentrations of potassium chloride (KCl) to mulberry plants resulted in higher level of total chlorophyll, total sugars, soluble protein, in vivo nitrate reductase activity (NRA), net photosynthetic rate (NPR), pWUE and leaf yield. Optimal concentration was found to be 10.0 mM KCl with limited irrigation provided in the mulberry plantation planted in 90 ${times}$ 90 cm spacing. The deleterious effect of soil moisture stress condition has been found to be overcome by KCl foliar spray twice at 15 days interval. Regression and correlation coefficients were analyzed, and a strong positive correlation was found between chlorophyll and total sugars, soluble protein and in vivo nitrate reductase activity, leaf dry weight and net photosynthetic rate and pWUE and net photosynthetic rate.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.431-434
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• 2003

This research developed a method for the estimation of groundwater recharge by yielding daily soil moisture content and watershed evapotranspiration from the water balance concept of the unsaturated and saturated layers in rainfall-runoff model called DAWAST. The goal of the research is to estimate the groundwater recharge fulfilling conditions of the safe discharge for any season. To meet this goal, the data of groundwater level and stream flow rate have been monitored in a study area and used to validate the model.

• Journal of Biosystems Engineering
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• v.19 no.2
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• pp.99-111
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• 1994

Automatic control system using microcomputer that have been studied in greenhouse, however, it was very difficult operation with success due to handicap for a various conditions and cultivated plants. This study was performed in order to develop of the basic program and hardware system for automatic control in greenhouse, such as automatic supplying of water, liquefied fertilizer solution and chemical solution. The results were summarized as follows. 1. The program for soil moisture control used by the switch type tensiometer was well operated. 2. The proximity switch was applied as well to water level control but it was very expensive, so low-priced sensor has to be developed. 3. The water meter was not excellent for mixing control of liquefied fertilizer, chemical and water, so water meter for only agricalture has to be developed. 4. Interface system for this study was suited to the developed controller. 5. Automatic control system to supply for water, liquefied fertilizer and chemical solution that was well operated as a fundamental study for product of controller.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.390-396
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• 2000

The basic concept of the model is minimizing the error range between forecasted flood inflow and actual flood inflow, and accurately forecasting the flood discharge some hours in advance depending on the concentration time(Tc) and soil moisture retention storage(Sa). Simplex method that is a multi-level optimization technique was used to search for the determination of the best parameters of RETFLO (REal-Time FLOod forecasting)model. The flood forecasting model developed was applied to several strom events of Yedang reservoir during past 10 years. Model perfomance was very good with relative errors of 10% for comparison of total runoff volume and with one hour delayed peak time.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.699-702
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• 2008

In this study, it has observed the precipitation and stage data at each point every ten minutes for gaining the sustainable, reliable and high-quality hydrological data through operating the experimental watershed in mountainous areas such as Gyecheon located in the upstream of Seom river that is the tributary of Nam-Han river. And it has regularly surveyed the runoff and verified the reliability of data using the uncertainty analysis at the gaging station. So, this study has developed the stage-discharge curve(rating curve) and these results are expected to be used as fundamental data for analyzing the circulation of water through surveying evapotranspiration, soil moisture and level of groundwater in watershed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.2
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• pp.187-194
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• 2016

In this paper, as a basic research for the restoration and construction of easuary saltmarsh, To observe the habitat environment for reed, we observed sediment environment (Particle size, water content, pH, nutrient analysis ($NH_4-N$, $PO_4-P$)), ground water level, ground level, individual numbers of reed, maximum reed height. As a result of this study, sediment particle size and moisture content of soil on the study area not effected reed habitat, pH showed no difference in each site. $NH_4-N$ and $PO_4-P$ concentration also no difference in each site. Ground level of reed habitat area is more higher than none reed habitat. However Ground water level of reed habitat area is more lower than none reed habitat. As a results of analyzing the influence factors for reed habitat in Nakdong estuary saltmarsh, ground water level and ground level is most influenced factor for reed habitat.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.3
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• pp.145-160
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• 1979

The effects of organic material application on soil physical properties were reviewed in relation to soil productivity. The organic matter contents and soil physical properties of the cultivated land in Korea were summarized and the effects of organic matter were compared in terms of land uses and soil types. Soil physical properties related to crop yield potential, such as soil aggregation, permeability, water holding capacity, erodibility, and compactibility, were used in evaluating the effects of organic materials as a soil physical amendment. The benefical effects of organic matter addition on soil physical conditions include (1) better aeration and increased infiltration in silty and clayey soils, (2) increased water holding capacity and moisture availability in sandy soils, (3) decreased soil erodibility, and (4) increased resistance to compaction. It is, therefore, concluded that continuous application of organic materials could greatly improve the various soil physical properties and favor the growth and yield of crops. A high rate of organic matter addition could contribute to reducing not only the soil erosion on sloping land, but also the possible detrimental effect of farm mechanization. In general, the effects of organic matter on soil physical improvement were estimated to be much higher in upland than in paddy. Organic matter would have a more pronounced effect on low productive lands such as heavy clayey or sandy soils and newly reclaimed soil. The optimum level of soil organic matter content was estimated to be about 3.0 to 3.5% for the best soil physical condition. Since the organic matter contents of the cultivated lands in Korea are much lower than optimum level, it would be desiable to use more organic materials to soil for the increase of soil productivity, continuation of stabilized high productivity and soil erosion control.

• Korean Journal of Soil Science and Fertilizer
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• v.24 no.3
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• pp.165-170
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• 1991

Effects of liming and starch application on the soil pH and mineralization of organic nitrogen were compared to control at $30+/10^{\circ}C$ incubation for six weeks in two soil types(loam, sandy loam) adjusted with 80% of field moisture capacity. 1. While soil pH was increased abruptyl one week after incubation in loam applied with lime and lime+starch, it tended to decrease at control during incubation period. Liming on sandy loam increased soil pH, and application of lime+starch together showed high pH at first week of incubation which was lowered slowly after wards. Significant changes in soil pH was not detected at control or starch application only. 2. The content of $NH_3-N$ in loam started to increse three weeks after incubation, and was maximized at fifth week. Positive correlation was shown at control during incubation period between soil pH and $NO_3-N$ content. Level of $NO_3-N$ content applied with starch or lime+starch was low compared to control. 3. The $NH_4-N$ content was high when sandy loam was applied with lime+starch together. At the first week of incubation, the $NO_3-N$ content was high at control or lime application.

• Journal of Practical Agriculture & Fisheries Research
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• v.21 no.2
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• pp.59-69
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• 2019

This study was carried out to investigate effects of soil water content on growth and antioxidative enzymes activity of tomato seedlings during the nursery period. The water stress significantly damages morphological, physiological, and biochemical activities in plants. The seedlings planted with soil on the tray were irrigated and categorized into 3 groups with 30 g, 40 g, and 50 g of plant-soil weight. After then, the changes in weight of the soil and the seedling were measured evey 2 hours for 4 days and the leaf temperature was measured with the thermal-camera at the same time. The antioxidant enzymes were measured to determine the level of stress using all of the seedling samples. The result showed that the decrease of soil weight in the day time was faster than that in the night time, but there was no significant difference in the weight loss of the seedlings and soil among the groups. However, the group with 50 g of wight showed the highest SOD and POD contents. This is considered that the continuously wet soil on the root zone of the seedlings caused more stress for the seedlings. Therefore, it is concluded that the excess moisture content causes stress to stimulate the secretion of antioxidant enzymes, and the effect of stress is required to be analyzed comprehensively using environmental data and also the physiological data that are collected over a longer period.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.5
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• pp.395-404
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• 2017

Cultivating soybeans in rice paddy field reduces labor costs and increases the yield. Soybeans, however, are highly susceptible to excessive soil water in paddy field. Controlled drainage system can adjust groundwater level (GWL) and control soil moisture content, resulting in improvement soil environments for optimum crop growth. The objective of this study was to fit the soybean growth data (canopy height and stem diameter) using Gompertz model and Logistic model at different GWL and validate those models. The soybean, Daewon cultivar, was grown on the lysimeters controlled GWL (20cm and 40cm). The soil textures were silt loam and sandy loam. The canopy height and stem diameter were measured from the 20th days after seeding until harvest. The Gompertz and Logistic models were fitted with the growth data and each growth rate and maximum growth value was estimated. At the canopy height, the $R_2$ and RMSE were 0.99 and 1.58 in Gompertz model and 0.99 and 1.33 in Logistic model, respectively. The large discrepancy was shown in full maturity stage (R8), where plants have shed substantial amount of leaves. Regardless of soil texture, the maximum growth values at 40cm GWL were greater than the value at 20cm GWL. The growth rates were larger at silt loam. At the stem diameter, the $R_2$ and RMSE were 0.96 and 0.27 in Gompertz model and 0.96 and 0.26 in Logistic model, respectively. Unlike the canopy height, the stem diameter in R8 stage didn't decrease significantly. At both GWLs, the maximum growth values and the growth rates at silt loam were all larger than the values at sandy loam. In conclusion, Gompertz model and Logistic model both well fit the canopy heights and stem diameters of soybeans. These growth models can provide invaluable information for the development of precision water management system.