• Korean Journal of Agricultural Science
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• v.41 no.4
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• pp.385-390
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• 2014

To evaluate the impact of nitrogen fertigation on crop growth and $NO_3$-N concentration in the soil solution, field experiment for cucumber cultivation during spring and fall season were carried out in on-farm located in Byeongcheon-myeon, Chunan-si, Chungcheonnam-do. Supplying nitrogen of 120-150 mg/L by fertigation device into soil per week reached to maximum yields of cucumber fruits. However, cucumber growth did not show any significant difference between nitrogen levels. Nitrogen supply of 400 mg/L, highest N levels, did not affect cucumber growth. Difference between green values of cucumber leaves using RGB scores were closely related with cucumber yields, and therefore, this results suggests that green values of cucumber leaves could be used as a way of determining the application rates of nitrogen for cucumber cultivation period under fertigation system.

• Journal of Environmental Science International
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• v.9 no.1
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• pp.43-47
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• 2000

A study on the remediation of heavily for ion contaminated soils from abandoned iron mine was carried out, using ex-situ extraction process. Also, oxalic acid as a complex agent was evaluated as a function of concentration, reaction time and mixing ratio of washing agent in order to evaluate Fe removability of the soil contaminated from the abandoned iron mine. Oxalic acid showed a better extraction performance than 0.1N-HCl, i.e., the concentrations of Fe ion extracted from the abandoned mine for the former at uncontrolled pH and the latter were 1,750 ppm and 1,079 ppm, respectively. The optimum washing condition of oxalic acid was in the ratio of 1:5 and 1:10 between soil and acid solution during l hr reaction. The total concentrations of Fe ion by oxalic acid and EDTA at three repeated extraction, were 4,554 ppm and 864 ppm, respectively. The recovery of Fe ions from washing solution was achieved, forming hydroxide precipitation and metal sulfide under excess of calcium hydroxide and sodium sulfide. In addition, the amounted of sodium sulfide and calcium hydroxide for the optimal revovery of Fe were 15g/$\ell$ and 5g/$\ell$ from the oxalic acid complexes, respectively.

• Korean journal of food and cookery science
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• v.17 no.5
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• pp.510-516
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• 2001

Hydroponic cultivation is a technology of raising crops without use of soil. Generally farmers use the method of DFT(deep flow technology)to grow leafy or fruity vegetables; however, systematic and scientific researches are insufficient on this matter. This study investigated the possibility of cultivating Chinese cabbage steadily year long by using the method of DFT. Chinese cabbage was cultivated hydroponically with and without Ge addition, used to prepare kimchi, and the chemical and microbiological characteristics of kimchi were compared. The basic hydroponic cultivation condition was as follows: 30 days after seeding, the raised seeds were moved to a hydroponic bed and given underground water for 3 days so the roots grow normally Standard nutrient solution was provided and the early electric conductivity concentration was maintained between 1.5∼2.5 thickness. The temperature of the solution was maintained between 10 ∼25$^{\circ}C$ to allow the growth of Chinese cabbage. When soil-cultivated, organically cultivated and hydroponically cultivated Chinese cabbages were compared, hydroponically cultivated cabbages were smaller in size and showed less ability to build up and fold leaves into a head, but showed better quality than organically cultivated cabbages. The contents of protein and fat showed no significant differences. The contents of water. Ca, P, Fe, Vitamin A and Niacin were higher in control and Ge-added cabbages compared with soil-grown cabbage. There was no difference between soil-cultivated Chinese cabbage kimchi and hydroponically cultivated Chinese cabbage kimchi.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.373-381
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• 2005

The permeability of contaminated soil and elapsed time are important considering factors to in-situ soil remadiation. Gabr et. al. (1996) derived the solution equation of contaminant concentration ratio as initial one (C/$C_0$) with time and spatial changes in contaminated area which embedded with vertical drains. The contaminant concentration ratio (C/$C_0$) is analyzed with time and spatial changes in three different permeability areas which are $k=l.0{\times}10^{-5,}$ $l.0{\times}l0^{-6,}$ $l.0{\times}l0^{-7}\;_{m/s}$ by using the Gabr's equation. Results from numerical analysis indicate that the ratio (C/$C_0$) decreases as the elapsed time increases in every point, however, remediation efficiency decreases as the analyzing point is far from injection well to extraction one and is deeper from top level of contaminated area. And also it decreases as the permeability of contaminated area decreases. Especially, the lower permeability of contaminated area effects directly on the soil remediation, in this research, under condition which the permeability of contaminated area is $l.0{\times}l0^{-7}\;_{m/s}$, the maximum time needed to attain 90% clean up level ($t_{90}$) is 65,690 hours(7.5 years), it takes so much time to clean the low permeability contaminated soil.

• Journal of Environmental Science International
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• v.30 no.10
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• pp.803-809
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• 2021

This study aimed to investigate the effects of soil amendment (heat-expanded clay and active carbon) and planting of Dendranthema zawadskii var. latilobum on the remediation of salt-affected soil and the plant growth under high calcium chloride (CaCl₂) concentration. The experimental group comprised treatments including Non treatment (Cont.), heat-expanded clay (H), active carbon (AC), planting (P), heat-expanded clay+planting (H+P), active carbon+planting (AC+P). A 200 mL solution of CaCl₂ at a concentration of 10 g·L^-1 was applied as irrigation once every 2 weeks. Compared to the Cont., the incorporation of the 'heat-expanded clay' amendment decreased electrical conductivity of the soil leachate and cation exchange capacity, whereas the growth of Dendranthema zawadskii var. latilobum was relatively increased. These results suggest that the combination of 'heat-expanded clay' amendment and planting will mitigate negative effect of de-icing salts and improve plant growth in salt-contaminated roadside soils.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.336-342
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• 2010

In a pot experiment, we studied the effect of nitrification inhibition on Fe reduction and P release in paddy soil and growth and nutrient uptake of rice plant. Recommended level of fertilizers, 6 kg N, 5 kg $P_2O_5$ and 4 kg $K_2O$ per 10a, were applied, and for N fertilizer urea, urea+N-serve, and $KNO_3$ were included. Four 30-day-old seedlings were transplanted in a waterlogged 9 L pot filled with Yuga series soil, and 3 pots were prepared in each N fertilizer treatment. Changes of soil redox potential and concentration of ${NH_4}^-$, ${NO_3}^-$, $Fe^{2+}$ and ${PO_4}^{3-}$ in soil solution at 10 cm depth were monitored, and also the growth and nutrient uptake of rice plants were measured. Concentration of ${NH_4}^+$ in soil solution was highest in urea+N-serve treatment, and followed by urea and $KNO_3$ treatments. Addition of N-serve could effectively inhibit nitrification in the soil. In the treatment of $KNO_3$, relatively higher ${NO_3}^-$ concentration was found at 10 cm depth soil. In urea+N-serve treatment redox potential was lower than -100 mV during the experiment, but in the treatment of $KNO_3$ the potential was maintained above 0 mV until ${NO_3}^-$ remaining in soil solution. Reduction of Fe(III) and solubilization of P were highly correlated with redox potential changes in the three N fertilizer treatments. Concentrations of Fe(II) and ${PO_4}^{3-}$ in soil solution at 10 cm depth were much higher in the urea+N-serve treatment. The most vigorous rice seedling growth was found in the urea treatment. Although the availability of N and P in soil was enhanced in the urea+N-serve treatment through the suppression of nitrification, excessive solubilization of Fe could limit the growth of rice plants.

• Journal of the Korea Furniture Society
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• v.29 no.1
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• pp.18-23
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• 2018

The purpose of this study was to develop wood pots for create Optimum environment of plant growth using unused wood. to prove this, we examined the effects of cycle of water supply and nutrient concentration in wood pots on plant germination rate and growth factors (leaf number, stem diameter and length). The results are as follows. 1) The growth rate was higher at once of 2 days watering period. This suggests that the growth of the plants was better than that of the less water because the larch pots itself has the water retention capacity inside. 2) Germination rate and growth rate were better than other treatment groups when the concentration of nutrient solution was 0.5%. 3) Nitrogen, available phosphoric acid, and potassium showed higher contents than the nutrient - treated soil at 0.5% concentration of nutrient solution. This indicates that the nutrient solution absorbed from the larch affected the soil and plant growth in the inside.

• Geomechanics and Engineering
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• v.32 no.3
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• pp.347-359
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• 2023

With the development of infrastructure, there is a critical shortage of filling materials all over the word. However, a large amount of silt accumulated in the lower reaches of the Yellow River is treated as waste every year, which will cause environmental pollution and waste of resources. Microbial induced calcium carbonate precipitation (MICP) technology, with the advantage of efficient, economical and environmentally friendly protection, is selected to solidify the abandoned Yellow River silt with poor mechanical properties into high-quality filling material in this paper. Based on unconfined compressive strength (UCS) test, determination of calcium carbonate (CaCO₃) content and scanning electron microscope (SEM) test, the effects of cementation solution concentration, treatment times and relative density on the solidification effect were studied. The results show that the loose silt particles can be effectively solidified together into filling material with excellent mechanical properties through MICP technology. The concentration of cementation solution have a significant impact on the solidification effect, and the reasonable concentration of cementation solution is 1.5 mol/L. With the increase of treatment times, the pores in the soil are filled with CaCO₃, and the UCS of the specimens after 10 times of treatment can reach 2.5 MPa with a relatively high CaCO₃ content of 26%. With the improvement of treatment degree, the influence of relative density on the UCS increases gradually. Microscopic analysis revealed that after MICP reinforcement, CaCO₃ adhered to the surface of soil particles and cemented with each other to form a dense structure.

• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.740-747
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• 2015

This research was performed to evaluate the feasibility of in situ soil flushing for TPH-contaminated soil remediation. It was conducted in batch test as fundamental research for in situ soil flushing. The 30% of initial TPH concentration was removed by shaking only in batch test. The removal efficiency of TPH in case of groundwater as surfactant dilution solution was approximate 2~6% lower than that of distilled water. Mixing ratio of soil to surfactant solution did not practically effect on the TPH removal efficiency. In the experiment of using single or mixed surfactant solution with 0.1~4.0 wt%, Tween-80, SWA-1503, SWA-1503+SDS showed averagely over 80%. It was determined that the optimum surfactant concentration was 0.1 wt% because there was no significant difference between concentrations of 0.1~4.0 wt%.

• Journal of Korean Society of Forest Science
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• v.97 no.3
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• pp.266-273
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• 2008

The effects of soil acidification on the seedling growth and nutrition of Pinus densiflora and Quercus acutissima were investigated. The relationship between the seedling growth and molar (Ca+Mg+K)/Al ratio of in soil solution was examined. The results suggested that growth inhibition of seedling Pinus densiflora and Quercus acutissima was due to the low pH of soil solution, which was followed by leach of Al into soil solution, and decrease of essential elements, such as Ca in aerial pant of the seeding caused by the increase of Al concentration in subterranean pant of the seedlings. The level of growth inhibition was determined not only by Al concentration, but also by the balance of inorganic elements, Al, Ca, Mg and K. The growths of two species in total dry weight were clearly inhibited when molar (Ca+Mg+K)/Al ratio of the soil was lower than 6.0. The growth in dry weight, in the condition of the molar ratio was 0.8, was decreased 60% or 50% for the seedling of Pinus densiflora or Quercus acutissima respectively. It was concluded that the molar (Ca+Mg+K)/ Al ratio could be an important index for evaluation of the effects of soil acidification, due to acid deposition such as acid rain, on growth of trees and nutrition. And it might be a more useful indicator for evaluation of critical load of acid deposition on forest ecosystems.