• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.444-451
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• 2022

Recently, long-term cultivation is becoming more common with the increase in tomato hydroponics. In hydroponics, it is very important to supply an appropriate nutrient solution considering the nutrient and moisture requirements of crops, in terms of productivity, resource use, and environmental conservation. Since seasonal environmental changes appear severely in long-term cultivation, it is so critical to manage irrigation control considering these changes. Therefore, this study was carried out to investigate the effect of irrigation volume on growth and yield in tomato long-term cultivation using coir substrate. The irrigation volume was adjusted at 4 levels (high, medium high, medium low and low) by different irrigation frequency. Irrigation scheduling (frequency) was controlled based on solar radiation which measured by radiation sensor installed outside the greenhouse and performed whenever accumulated solar radiation energy reached set value. Set value of integrated solar radiation was changed by the growing season. The results revealed that the higher irrigation volume caused the higher drainage rate, which could prevent the EC of drainage from rising excessively. As the cultivation period elapsed, the EC of the drainage increased. And the lower irrigation volume supplied, the more the increase in EC of the drainage. Plant length was shorter in the low irrigation volume treatment compared to the other treatments. But irrigation volume did not affect the number of nodes and fruit clusters. The number of fruit settings was not significantly affected by the irrigation volume in general, but high irrigation volume significantly decreased fruit setting and yield of the 12-15th cluster developed during low temperature period. Blossom-end rot occurred early with a high incidence rate in the low irrigation volume treatment group. The highest weight fruits was obtained from the high irrigation treatment group, while the medium high treatment group had the highest total yield. As a result of the experiment, it could be confirmed the effect of irrigation amount on the nutrient and moisture stabilization in the root zone and yield, in addition to the importance of proper irrigation control when cultivating tomato plants hydroponically using coir substrate. Therefore, it is necessary to continue the research on this topic, as it is judged that the precise irrigation control algorithm based on root zone-information applied to the integrated environmental control system, will contribute to the improvement of crop productivity as well as the development of hydroponics control techniques.

• Journal of Environmental Science International
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• v.14 no.12
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• pp.1185-1194
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• 2005

The runoff characteristics of non-point source pollutions in the municipal area of Jeonju were investigated and analyzed by using the SWMM (Storm Water Management Model). The flow rates and water qualities of runoff from two types of drainage conduits were measured respectively. One was a conventional combined sewer system and the other was a separated sewer system constructed recently From August to November in 2004, investigations on two rainfall events were performed and flow rate, pH, BOD, COD, SS, T-N and T-P were measured. These data were also used for model calibration. On the basis of the measured data and the simulation results by SWMM, it is reported that $80-90\%$ of pollution load is discharged in the early-stage storm runoff. Therefore, initial 10-30 mm of rainfall should be controlled effectively for the optimal treatment of non-point source pollution in urban area. Also, it was shown that the SWMM model was suitable for the management of non-point source pollution in the urban area and for the analysis of runoff characteristics of pollutant loads.

• Economic and Environmental Geology
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• v.31 no.2
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• pp.101-110
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• 1998

The purpose of this study is to elucidate the source of U anormaly formed in stream water of the drainage system around the Shinbo talc mine area based on the hydrochemical properties of water masses including surface water and groundwater. The hydrochemical properties of water masses in the Shinbo talc mine area are divide into three types; Type I : $Ca(Mg)SO_4$ type with high U content as shown in the stream water flowout from the mine, Type II : $Ca(HCO_3)_2$ type with high U content as in deep groundwater, Type III : $Ca(HCO_3)_2$, type with low U content as in the other stream water and shallow groundwater. It is necessary to emphasize that in deducing the uranium source, a distinct discrimination between type I and type II is showed in their hydrothermal properties in spite of commonly having a high uranium content, which in turn means the occurrence of a different water-rock interaction processes between both type. All evidences suggest that type II groundwater have acted as a primary media in the transport of uranium and that, as the groundwater flows through the talc mineralization zone, water composition of type II was transformed into that of type I water as the results of a secondary water rock interaction process, caused by imposition of new mineralogically controlled thermodynamic constraints. Consequently, in the viewpoint of hydrochemical exploration, the investigation of the hydrologic circulation system and the hydrogeologic properties for the aquifer of type II groundwater shall be done first of all and will provide a crucial clue on tracing the uranium mineralization zone occurred in the Shinbo talc mine area.

• 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.

• Journal of Korean Neurosurgical Society
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• v.38 no.4
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• pp.281-286
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• 2005

Objective : The authors report our experience of urokinase thrombolysis in treating patients harboring nonaneurysmal spontanesous intraventricular hemorrhage[IVH] and evaluated complications, safety and feasibility of this procedure retrospectively. Methods : Fifty-three patients with nonaneurysmal IVH>15mL without underlying structural etiology or coagulopathy were recruited. The patients with Glasgow Coma Scale[GCS]<5 were excluded. A catheter was directed into the IVH. Hematoma aspiration was followed by instillation of urokinase at the ear level of drainage bag under intracranial pressure monitoring system. This was repeated every 6hours until half of its initial volume. For analysis of prognostic factors, we classified the patients into two groups by Glasgow outcome scale[GOS]; good [$GOS\;{\ge}3$] and bad [GOS<3] prognosis group, and performed comparative analysis between two groups. Results : Mean age was 60.2years. The baseline hematoma size ranged 16 to 72mL. IVH volume reduction was done by an average of 74.2%. As complications, there were 3cases of rebleeding and 2cases of ventriculitis. No intracranial adverse effects were observed during thrombolytic theraphy. At 6months after the procedure, 29patients had achieved a good recovery, 15remained vegetative. 9patients died in hospital. The main good prognostic factors were young age, small IVH volume, and high GCS. Conclusion : The results of this study suggest that this relatively easy and safe method of treatment will improve the prognosis. However, further clinical studies also must assess optimal thrombolytic dosage, frequency, and timing of urokinase instillation for safety and effectiveness and must include controlled comparisons of mortality, disability outcome, quality of life, time until convalescence, and cost of care in treated and untreated patients.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.1
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• pp.1-28
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• 2019

This study analyzed the density and mortality rate of Korean fir at 9 sites where individuals of Korean firs were marked into the live and dead trees with coordinates on orthorectified aerial images by digital photogrammetric system. As a result of the analysis, Korean fir in each site showed considerable heterogeneity in density and mortality rate depending on the location within site. This make it possible to assume that death of Korean fir can occur by specific factors that vary depending on the location. Based on the analyzed densities and mortality rates of Korea fir, we investigated the correlation between topographic factors such as altitude, terrain slope, drainage network, solar radiation, aspect and the death of Korean fir. The density of Korean fir increases with altitude, and the mortality rate also increases. A negative correlation is found between the terrain slope and the mortality rate, and the mortality rate is higher in the gentle slope where the drainage network is less developed. In addition, it is recognized that depending on the aspect, the mortality rate varies greatly, and the mean solar radiation is higher in live Korean fir-dominant area than in dead Korean fir-dominant area. Overall, the mortality rate of Korean fir in Mt. Halla area is relatively higher in areas with relatively low terrain slope and low solar radiation. Considering the results of previous studies that the terrain slope has a strong negative correlation with soil moisture and the relationship between solar radiation and evaporation, these results lead us to infer that excess soil moisture is the cause of Korean fir mortality. These inferences are supported by a series of climate change phenomena such as precipitation increase, evaporation decrease, and reduced sunshine duration in the Korean peninsula including Jeju Island, increase in mortality rate along with increased precipitation according to the elevation of Mt. Halla and the vegetation change in the mountain. It is expected that the spatial patterns in the density and mortality rate of Korean fir, which are controlled by topography such as altitude, slope, aspect, solar radiation, drainage network, can be used as spatial variables in future numerical modeling studies on the death or decline of Korean fir. In addition, the method of forest distribution survey using the orthorectified aerial images can be widely used as a numerical monitoring technique in long - term vegetation change research.

• Journal of Bio-Environment Control
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• v.21 no.1
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• pp.12-19
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• 2012

This research was performed to determine the appropriate daily last irrigation time to enhance the plant growth and the water and fertilizer use efficiencies in coir bag culture for tomato plant. The time to finish the daily irrigation was set by 1, 2, 3 and 4 hours before the sunset. The water content in the substrate was greatly affected by the last irrigation time. The earlier the last time, the greater the daily fluctuation of water contents in the substrate. The daily irrigation times were not affected by using irrigation management system controlled by drainage electrodes or the physiochemical properties of coir. The growth characteristics were not significantly different among the treatments. The highest marketable yields were obtained in the treatment finishing two hours before sunset, and the lowest yields were obtained in the the treatment finishing 4 hours before sunset. Based on the result from surveying quantity of irrigated water for 128 days of the experiment period, the water and fertilizer use efficiencies were lowest in the treatment finishing 4 hours before sunset, and the highest in the treatment finishing 2 hours before sunset. In terms of plant growth, yields, water and fertilizer use efficiencies, 2 hours before sunset treatment was determined as the most economical and desirable irrigation schedule.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.983-991
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• 2012

These days, agricultural products cultivated in facilities occupy the highest percentage of agricultural output price. Specifically cucumbers have been one of the crops that farmers prefer to growing, because their prices were high. However, cucumber crop is sensitive to the soil and environments and it requires the exact crop management. In order to establish cultivation techniques for cucumbers, the current situation of cucumber cultivation was surveyed from ten cucumber farmlands; five farmlands of cucumber cultivation in forcing and five of semi-forcing practicing systems, respectably. The soil conditions were alluvial or valley in soil topology, moderately or poorly drainage in soil drainage classes, coarse loamy in soil texture family. Soil was managed with deep plowing combined with application of basal fertilizers such as compost, rice straw, oil cake, wood chip and chemical fertilizer. The whole soil was prepared in uniformly with rotary. Three major nutrients ($N-P_2O_5-K_2O$)of basal application were 815-464-529 kg $ha^{-1}$ in forcing and 197-135-151 kg $ha^{-1}$ in semi-forcing cultivation. Top dressing of fertilizer was supplied in fertigation system of macro and micro elements in 2~3 day interval with water irrigation. The average yields of cucumbers were $168t\;ha^{-1}$ with 381,000 thousand won $ha^{-1}$ in average gross profit (AGP) in forcing cultivation and $115t\;ha^{-1}$ with 177,000 thousand won $ha^{-1}$ in AGP in semi-forcing cultivation. Cucumber production during the winter season was considered to increase the gross profit because cucumber price tends to stay in high level during this time. The accumulation of soil chemicals like EC, available $P_2O_5$ and exchangeable cations could be controlled by rice straw application. The rice straw application increased soil temperature during the winter season, in exchange of soil air, and in extension of plant roots. In addition, the rice straw application somewhat affected decrease of salts accumulation.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.398-410
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• 1982

Summer crops grown in uplands are greatly diversified and show a large variation in difference with year and location in Korea. The principal factor for the variation is weather, in which precipitation and temperature play a leading role and such a weather factors as wind, sun lights also influence production of the summer crops. Since artificial control of weather conditions as a main stress factor for crop production is almost impossible, it must be minimized only by an improvement of cultivation techniques and crop improvement. Precipitation plays a role as one of the most important factor for production of the summer crops and it is considered in two aspects, drought and excess moisture. This country, which belongs to monsoon territory, necessarily encounter one of this stress almost every year, even though the level is different. Therefore, the facilities for both drought and excess moisture are required, but actually it is not easy to complete for them. On this account, crops tolerant to drought, excess moisture and pests should be considered for establishing summer crops. For the districts damaged habitually every season, adequate crops should be cultured and appropriate method of planting, drainage and weed control should be applied diversely. Injuries by temperature is mainly attributed to lower temperature particularly in late fall and early spring, although higher temperature often causes some damages depending upon the kind of crops. Sometimes, lower temperature in summer season playa critical role for yield reduction in the summer crops. However, certain crops are prevented to some extent from this kind of stress by improving varieties tolerant to cold, hot weather or early maturing varieties. As is often the case, control of planting time or harvesting is able to be a good management for escaping the stress. Lodging, plant diseases and pests are considered as a direct or indirect damage due to weather stress, but these are characters able to be overcome by means of crop improvement and also controlled by other suitable methods. In addition, polytical supports capable of improving constitution of agriculture into modern industry is urgently required by programming of data for the damages, establishment of damage forecasting and compensation system.