• The Journal of Engineering Geology
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• v.21 no.2
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• pp.125-131
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• 2011

The discharge characteristics of the Seodo Mulgol Spring-the only groundwater-producing area in Dokdo-were evaluated by measurements of discharge rate and electrical conductivity (EC) on five occasions. The Seodo Mulgol Spring is fed by rainfall in upstream areas of the Mulgol cave, and the rainwater of the area moves down along cooling joints developed in trachyandesite II and trachyte, finally discharging at the Mulgol cave. The discharge rate of the Seodo Mulgol Spring varied from 1.12 to 7.02 $m^3/d$ during the study period and EC varied from 2,650 to 3,390 ${\mu}S/cm$, showing a sharp increase during heavy rainfall. The observed variations in discharge rate and EC at the Seodo Mulgol Spring are attributed to the relatively short distance between the recharge area and the Mulgol cave, and to the rapid movement of groundwater through columnar joints developed in trachyandesite II and trachyte. Additional discharge measurements, combined with precise rainfall data, are required at Dokdo to elucidate the discharge characteristics of the Seodo Mulgol Spring.

• Journal of Bio-Environment Control
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• v.10 no.3
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• pp.133-140
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• 2001

This study was conducted to develop a nutrient uptake model in cucumnber (Cucumis sativus L. cv. Eunsung Backdadagi) plants for prediction of the amount of nutrients in drainage solution in a closed perlite culture system. Electrical conductivity (EC) of the nutrient solution was adjusted to 1.5, 1.8, 2.1, 2.4, and 2.7 dS. $m^{-1}$ . The amount of nutrient solution absorbed in different EC treatments was not different until the mid stage of growth. However, after the mid growth stage, a high EC treatment resulted in less solution absorption. The absorption rates of K, N $O_3$$^{[-10]}$ -N, Mg, and P increased continuously for a whole growing period in all treatments, while those of Ca decreased slightly. For S, the decrease was significant after th mid stage of growth. although the amounts of absorbed inorganic ions in different EC treatments were not significantly different at the first stage of growth, they were significantly different after the mid stage of growth and decreased slightly at the end of growth stage. Models for predicting the amounts of each inorganic ion absorbed were developed by using EC and the amount of nutrient solution absorbed per unit radiation(mg.M $J^{-1}$), which proved to be practical with a positive correlation at 1 percent probability between the developed model and practical values..

• Journal of Bio-Environment Control
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• v.18 no.4
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• pp.377-384
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• 2009

This study was conducted to examine the effects of electrical conductivity (EC) and rootstock on initial growth and physiological response of grafted pepper in protected cultivation. The pepper (Capcicum annuum L.) cultivars 'Nokgwang' was used as scions, and the cultivars used as rootstocks were Capcicum annuum L: 'Kataguruma', 'Conesian hot' and 'Tantan'. The scion cultivar left ungrafted was used as a control. Two experiments were to examine the effects of the EC levels of nutrient solution on the growth and physiological response of grafted pepper, respectively. Nutrient solution was supplied with three level (1.5, 3.0, 5.0dS/m). By the change of nutrient solution EC level, the plant growth of all seedlings decreased with the increase in EC level. grafted seedling was grafted onto rootstock cultivar 'kataguruma' showed higher growth than the other cultivar at the EC 5.0dS/m level. But this result was slightly different by cultivation time (spring and fall). The total N and P concentration were increased with the increase in EC level, but the Ca and Mg concentration were decreased. Photosynthetic rate of ungrafted seedlings decreased at the EC 5.0dS/m level. But there was no difference between EC 1.5 and 3.0dS/m level. Grafted seedlings showed lower photosynthetic rate at the EC 5.0dS/m level. The activity of SOD do not have a uniformly tendency by the EC level. With the EC 5.0dS/m level, the activity of APX attained higher level than the other EC level. Further study will be needed to examine additional cultivation experiment for more variable rootstock, and development of rootstock for salinity tolerance.

• Economic and Environmental Geology
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• v.50 no.4
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• pp.267-276
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• 2017

Seawater intrusion into coastal fractured rock aquifer, resulting in groundwater contamination, is of serious concern in coastal areas of Jeolla Namdo, Korea, which heavily depends on groundwater resources. Time series analysis and forecasting were carried out to analyze and predict EC which is a major indicator of seawater intrusion. Two time series models of autoregressive integrated moving average (ARIMA) and seasonal autoregressive integrated moving average (SARIMA) were tested for suggesting appropriate time series model. Time series data of EC measured over one year showed a increasing trend with short periodic fluctuations, due to tidal effect and pumping, which indicated that EC time series data tended to be non-stationary. SARIMA model was found better fitted to observed EC than any other time series model. Time series analysis and modeling was found to be a useful tool to analyze EC at coastal fractured rock aquifer subject to seawater intrusion.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.1
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• pp.178-184
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• 2007

In the present work, the vermicomposting index was investigated using leakage water from sludge to develop the process of mechanization and automation in the earthworm-cast treatment. The in situ sewage sludge was used batch and continuous experiments. Due to different treatment processes, the physico-chemical characteristics of liquid extracted from sludge was the similar change pattern. However, some items, such as Oxidation Reduction Potential (ORP), pH, Electrical Conductivity (EC) and $NH_3-N$, showed the distinct changes between pre- and post-vermicomposting. Also, The ORP and EC were the best parameters for the vermicomposting index. These results offered that the present vermicomposting technology was an actual earthworm-cast treatment.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.405-408
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• 2002

The electrical conductivity, EC is a major indicator of soil salinity. Measuring EC of saturation-paste extract of soil, ECe, is the standard way to evaluate soil salinity. However much of the data on soil salinity have been obtained by measuring the EC of the 1:5 soil-to-water extract, EC(1:5) or salts contents(%) which multiplied by conversion factor. And, thus we attempted to collect and analysis 90 soil samples at 9 reclaimed tidelands in Korea and to derive a relationship between ECe and dilution factor at ECe and EC(1:5), $DF_{1:5}$ of 3 soil textural conditions and 6 salinity conditions. Regression equations between ECe and $DF_{1:5}$ were obtained $ECe=1.4701ln(DF_{1:5})+5.0974(r^2=0.97^{**})$ in case of more than 50% silt contents, $ECe=2.1399ln(DF_{1:5})+5.3462 (r^2=0.99^{***})$ in case of below 50% silt contents, and $ECe=1.5927ln(DF_{1:5})+5.2486 (r^2=0.98^{***})$ in all cases, and then we suggested the $DF_{1:5}\;and\;DF_%$ of 3 soil textural conditions and 6 salinity conditions.

• Horticultural Science & Technology
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• v.31 no.2
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• pp.173-178
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• 2013

Experiments were conducted to investigate the optimum concentration of nutrient solution for strawberry 'Maehyang' bred domestically for exportation in hydroponics. Nutrient solutions for strawberry, which was made by Yamazaki, were supplied electrical conductivity (EC) 0.6, 0.8, 1.2, and $1.8dS{\cdot}m^{-1}$ after planting on cocopeat medium during the experiment period. Growth of shoot of strawberries did not show any statistical differences among treatments. Fruit length showed the longest in EC 0.8 and $1.2dS{\cdot}m^{-1}$, followed by 0.6 and $1.8dS{\cdot}m^{-1}$ in the first and third cluster. It showed the shortest in EC $1.8dS{\cdot}m^{-1}$ in the second cluster but there were no significant differences among treatments in the fourth cluster. Fruit diameter did not show significant differences among treatments in the first and second cluster but was the longest in the lowest concentration EC $0.6dS{\cdot}m^{-1}$ in the third cluster. The shortest was in EC $1.8dS{\cdot}m^{-1}$ in the fourth cluster. The heaviest mean fruit weight appeared in EC 0.8 and $1.2dS{\cdot}m^{-1}$, and the lightest was in EC $1.8dS{\cdot}m^{-1}$ in the first cluster and also lightest in EC $1.8dS{\cdot}m^{-1}$ but no significant differences was found among other treatments in the second & third cluster. Also the fruit weight was significantly light in plants grown in EC $1.8dS{\cdot}m^{-1}$ than $0.6dS{\cdot}m^{-1}$ in the fourth cluster. Soluble solids content of fruit was the highest in EC $0.6dS{\cdot}m^{-1}$ in all cluster. As a result, we came to the conclusion that the optimum EC for strawberry 'Maehyang' was EC 0.8 - $1.2dS{\cdot}m^{-1}$ during low temperature season. This result will be utilized as an indicator for strawberry hydroponics.

• KCID journal
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• v.11 no.1
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• pp.45-56
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• 2004

This study was performed In order to analyze the changes of electrical conductivity (EC) by the fertilization treatments during the rice owing period in Saemangeum reclaimed tidal land soils. The objective of this study was to offer fundamental data for i

• Membrane and Water Treatment
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• v.14 no.4
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• pp.163-173
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• 2023

The presence of high amounts of organic and inorganic contaminants in textile wastewater is a major environmental concern. Therefore, the treatment of textile wastewater is an urgent issue to save the aquatic environment. The disposal of large quantities of untreated textile wastewater into inland water bodies can cause serious water pollution. In this study, synthetic dye wastewater samples were prepared using orange dye in the laboratory. The synthetic samples were then treated by a batch adsorption process using the prepared activated carbon (AC) from date pits. The wastewater parameters studied were the pH, total dissolved solids (TDS), total suspended solids (TSS), electrical conductivity (EC) and salinity. The activated adsorption process showed that the maximum removal efficiencies of electric conductivity (EC), salinity, TDS and TSS were 65%, 92%, 89% and 90%, respectively. The removal efficiencies were proportional to the increase in contact time (30-120 min) and AC adsorbent dose (1, 3 and 5 g/L). The adsorption profile indicates that 5 g/L of adsorbent delivers better results for TDS, EC, TSS and salinity at contact time of 120 min. The adsorption characteristics are better suited to the pseudo-second-order kinetic model than to the pseudo-first-order kinetic model. The Langmuir and Freundlich isotherms were well suited for describing the adsorption or contact behavior of EC and TSS within the studied system.

• Journal of information and communication convergence engineering
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• v.20 no.1
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• pp.49-57
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• 2022

Fertilizers have long been used to increase crop yields; however, farmers are still having difficulties in managing fertilizers for growing crops as well as economic problems. The conventional method of soil sampling and laboratory analysis to determine soil pH is time consuming and costly; therefore, a portable pH sensor is developed to characterize spatial or temporal variability within fields via rapid and dense data acquisition. The portable pH sensor comprises an electrode unit, a portable console, and a USB connector. The soil water content (SWC) and electrical conductivity (EC) affect the electrical resistance of soil. An artificial test soil is performed to evaluate the effect of SWC and EC on soil pH. The test results show that stable pH measurements are achieved at SWCs greater than 20 mL (16.3%). Regardless of the SWC, the electric potential difference (EPD) remains at 2.5 g of NaCl. As the EC increases in the soil samples, the EPD increases.