• Korean Journal of Soil Science and Fertilizer
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• 제29권4호
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• pp.411-418
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• 1996

This experiment was conducted to investigate the effect of electric conductivity (EC) and potassium (K) concentration level in the culture solution on the growth and the air pollution monitoring capability of Perilla frutescens Suwon 16 which was recognized as a possible bioindicator for air pollution. The plants were exposed to $NO_2$, $O_3$, $SO_2$ and $NO_2+SO_2$ within a phytotron at $25^{\circ}C$ (day) or at $20^{\circ}C$(night) with 70% of relative humidity and evaluated the effect of EC and K level on the injury of the plants, The highest dry weights were gained as 16.3 g/plant at 0.5 dS/m of EC and as 32.3 g/plant at 100 and 200mg/l of K concentration, respectively. The diffusive resistances appeared as low values at 0.5 dS/m of EC and at 50, 100mg/l of K concentration. The increasing of the visible injury with increasing the dose of air pollutants could be taken at 0.5. 1.0 ds/m of EC and at 50, 100mg/l of K. The recommendable level of EC and K of the culture solution were 0.5-1.0 dS/m of electric conductivity. 50-100mg/l of K for the plant as an air pollutant biomonitor, when the 7th or 8th leaf was developed.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2007년도 춘계학술대회
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• pp.445-448
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• 2007

Three boreholes (BE-1, BE-2 and BE-3) were drilled for geothermal resources development in Haengbok (Sejong) city. Monitoring of temperature, electric conductivity (EC) and piezometric head were carried out at each borehole. Temperatures were measured at 10 m depth, it ranges from 13.22$^{\cdot}C$ to 14.4$^{\cdot}C$. EC of BE-1 and BE-3 declined with time because groundwater flowed in boreholes. Barometric efficiency was analysed by piezometric head of groundwater and atmospheric pressure, it ranges from 44.8% to 71.5%. These parameters can be used for a geothermal modeling.

• Journal of Biosystems Engineering
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• 제20권4호
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• pp.383-389
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• 1995

This study was conducted to develop an automatic nutrient control system for trickle application of nutrient solution. Temperature, electric conductivity(EC). pH and dissolved oxygen(DO) were selected as control variables. A controller using single-chip microcomputer was constructed. An automatic control system for nutrient solution and a controller using single-chip microcomputer with control algorithm were developed. The control system was tested, and could control temperature, EC and pH within the error ranges of $pm 0.2^{circ} pm 0.2mS/cm, pm 0.1pH$, respectively.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.391-393
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• 2006

In this study, the performance of artificial neural network (ANN) models for estimating spatial distribution of water quality was evaluated using electric conductivity (EC) values in landfill site. For the ANN model development, feedforward neural networks and backpropagation algorithm with gradient descent method were used. In Test 1, the interpolation ability of the ANN model was evaluated. Results of the ANN model were more precise than those of the Kriging model. In Test 2, spatial distributions of EC values were predicted using precipitation data. Results seemed to be reasonable, however, they showed a limitation of ANN models in extrapolations.

• The Korean Journal of Ecology
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• 제20권2호
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• pp.133-143
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• 1997

From 1984 to 1989 reclaimed coastal lands in Choongnam Province of the western coast of Korea were studied for soil texture at three sites(Daeho, Hyundai A and Hyundai B) and for desalination one site(Hyundai B). The soil textures of varied sites in Hyundai A were horizontally similar and composed of 39-40% clay, 40-49% silt and 8-14% sand. But those in Da돼 and Hyundai B differed horizontally in the same area and vertically at the same site. Soil texures of Da돼 were composed of 15-17% clay, 30-45% silt and 40-55% sand and those of Hyundai B were composed of 22-45% clay, 26-49% silt and 17-31% sand. The measured electrical conductivity(EC), which represents whole salt content of the reclaimed soil, decreased year by year. The vertical distribution of the EC changed temporally and spatially in the upper zone above a 50 cm depth but not in The lower zone below a 50 cm depth. The EC valus of the soil were inversely proportional to the magnitued of annual precipitation, evaporation and the numbers of rainy days with r equalling -0.97. But the annual decrease of the EC was directly proportional to climatic factors with r=0.7. Salt in the reclaimed land was leached out by the percolative action of surplus rain water, or moved up by evaporation and carried away by running rain water. The running out of the salt on the soil surface was most efficiently carried out over 10 mm precipitation per day.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• 제20권12호
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• pp.1099-1104
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• 2007

In order to develop non-heated STAl(super thermal resistant Aluminum alloy) for ampacity gain conductor, the systematic research was carried out. Especailly, the effect of a very small amount of Zr, Sc element in EC grade Al ingot on mechanical and electrical properties was our priority. As a result, it was found that the strength and recrystallization temperature of designed alloy was gradually increased with Zr, Sc addition up to 0.3 wt.%. However, the electric conductivity showed no drastic change. The tensile strength and recrystalliztion temperature, $17.75{\sim}20.05\;kgf/mm^2$ and $420{\sim}520\;^{\circ}C$, was obtained at 0.3 wt.% Zr, Sc addition, respectively. Particles of the $Al_3Zr$ and $Al_3Sc$ phase affected the ambient and elevated-temperature strength of the alloys.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.519-520
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• 2007

In order to develop non-heated STAl(super thermal resistant Aluminum alloy) for ampacity gain conductor, the systematic research was carried out. Especially, the effect of a very small amount of Zr element in EC grade Al ingot on mechanical and electrical properties was our priority. As a result, it was found that the strength and recrystallization temperature of designed alloy was gradually increased with Zr addition up to 0.3wt.%. However, the electric conductivity showed no drastic change. The tensile strength and recrystalliztion temperature, $17.75\;kgf/mm^2$ and $420^{\circ}C$, was obtained at 0.3 wt.% Zr addition, respectively.

• Journal of the korean veterinary medical association
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• 제26권1호
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• pp.32-37
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• 1990

Clinical signs and electric conductivity(EC) of blood were serutinzed for the detection of the cattle being afflicted with forced administration of excessive water or salt water in an abattoir. Test animais were divided into 3 groups such as 10 normal cat

• Journal of information and communication convergence engineering
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• 제20권1호
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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.

• Korean Journal of Soil Science and Fertilizer
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• 제18권1호
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• pp.72-77
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• 1985

This study was performed to obtain some basic informations about the effects of irrigation water on the growth of rice plant. The water quality was surveyed at six pumping stations from the Nam river tributary to the downstream of Nakdong river, and sampling sites of soil and plant were five paddy fields near-by each station during rice growing periods in 1983. 1. Average value of COD was 5.1-7.1 ppm at 2 sites of the Nam river tributary, 11.4 ppm at 1 site of the midstream and 9.1-13.4 ppm at 3 sites of the downstream of Nakdong river. 2. The relationships between irrigation water and soil were $r=0.98^{**}$ for EC and $r=0.91^*$ for SAR, but the rest components did not. 3. Root activity of rice plant was low tendency as go by go the downstream of Nakdong river, and it was related to dry matter of rice plant ($r=0.62^{**}$), SAR ($r=-0.67^{**}$), and EC ($r=-0.62^{**}$) of soils.