• Horticultural Science & Technology
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• v.30 no.2
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• pp.144-151
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• 2012

Diagnosis of nutrient disorders in cultivating crops is based on the visual symptoms and results of soil and plant analysis. This study was carried out to investigate the influence of B concentrations in fertilizer solution on the growth of and nutrient uptake by domestically bred strawberries. Tissue analysis based on the dry weight were also conducted to determine the threshold levels in plants when toxicity developed in boron. The growth was seriously restricted in the three strawberry cultivars as the B concentrations in fertilizer solution were elevated. The fresh and dry weights were heavier and crown diameters were thicker in the 0.25 mM boron treatment than the other treatments tested. The toxicity symptoms of boron appeared on the older leaves of three strawberry cultivars while interveinal chlorosis symptoms appeared on the young leaves of 'Keumhyang' and 'Seolhyang' strawberries. The toxicity symptoms in lower leaves were developed when B concentrations in fertilizer solution were higher than 2 mM in 'Keumhyang' and 0.5 mM in 'Maehyang' and 'Seolhyang' strawberries. The elevated boron concentrations in fertilizer solution did not influence the tissue K, Ca, and Mg contents, but influenced the phosphorus contents with decreasing tendency. The tissue Fe and Zn contents decreased and increased, respectively, as the B concentrations in fertilizer solution were elevated. When the concentration of boron at which the growth of a plant is retarded by 10% is regarded as a upper threshold level, the boron contents based on dry weight of above ground plant tissue should be lower than 25.1, 44.2, and 62.5 $mg{\cdot}kg^{-1}$ in 'Keumhyang', 'Maehyang', and 'Seolhyang' strawberries, respectively.

• Korean Journal of Environmental Agriculture
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• v.38 no.2
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• pp.83-88
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• 2019

BACKGROUND: In recent years, studies on microplastics have focused on their decomposition in the ocean. However, no studies have been reported on the interaction between microplastics and metal ions in aqueous solutions. Therefore, this study was conducted to evaluate the adsorption capacity of cadmium(Cd) by polypropylene (PP) in aqueous solution. METHODS AND RESULTS: Cadmium adsorption characteristics of PP in aqueous solution were evaluated through various conditions including initial Cd concentration(1.25-25 mg/L), contact time(0.5-24 h), initial pH(2-6) and temperature($20-50^{\circ}C$). Cadmium adsorption fit on PP was well described by Freundlich isotherm model with adsorption capacity(K) of 0.028. The adsorption amount of Cd by PP increased with increasing contact time, indicating that adsorption of PP by Cd was dominantly influenced by contact time. Especially, the removal efficiency of Cd by PP was highest at high temperature. However, the surface functional groups of PP before and after adsorption of Cd were similar, suggesting that adsorption of Cd by PP is not related to surface functional groups. CONCLUSION: Our study suggests that PP affects the behavior of Cd in aqueous solution. However, in order to clarify the specific relationship between microplastics and metal ions, mechanism research should be carried out.

• Geomechanics and Engineering
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• v.38 no.4
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• pp.381-395
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• 2024

With the wide application of urban subway tunnels, the foundation pits of new stations and existing subway tunnels are becoming increasingly close, and even zero-distance close-fitting construction has taken place. To optimize the construction support scheme, the existing tunnel's vertical displacement is theoretically analyzed using the two-stage analysis method to understand the action mechanism of the construction of zero-distance deep large foundation pits on both sides of the existing stations; a three-dimensional numerical calculation is also performed for further analysis. First, the additional stress field on the existing tunnel caused by the unloading of zero-distance foundation pits on both sides of the tunnel is derived based on the Mindlin stress solution of a semi-infinite elastic body under internal load. Then, considering the existing subway tunnel's joints, shear stiffness, and shear soil deformation effect, the tunnel is regarded as a Timoshenko beam placed on the Kerr foundation; a sixth-order differential control equation of the tunnel under the action of additional stress is subsequently established for solving the vertical displacement of the tunnel. These theoretical calculation results are then compared with the numerical simulation results and monitoring data. Finally, an optimized foundation pit support scheme is obtained considering the pit corner effect and external corner failure mode. The research shows a high consistency between the monitoring data,analytical and numerical solution, and the closer the tunnel is to the foundation pit, the more uplift deformation will occur. The internal corner of the foundation pit can restrain the deformation of the tunnel and the retaining structure, while the external corner can cause local stress concentration on the diaphragm wall. The proposed optimization scheme can effectively reduce construction costs while meeting the safety requirements of foundation pit support structures.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.2
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• pp.112-117
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• 2002

This study was conducted to investigate effects on the co-situs application of coated urea complex fertilizer in dry seeded rice in Dukpyong series soil. Number of spikelet established in 15 days after seeding, conventional plot was $120ea\;per\;m^2$. and whole layer placement(WLP), co-situs application 70%(CSA70%) plot and co-situs application 50%(CSA50%) plot were 146, 126 and $120ea\;per\;m^2$, respectively. There was not concentration obstacle in co-situs application plot in spite of closing application between seed and coated urea complex fertilizer. The amount of $NH_4-N$ into soil solution in different growth stage was highest in WLP 70% plot compare to other treatment. N uptaken amount was highest in CSA 70% plot as $94kg\;ha^{-1}$ compare to $90kg\;ha^{-1}$ of WLP 79% plot and $82kg\;ha^{-1}$ of CSA 50% plot. However, N use efficiency of CSA 50% plot was highest among treatments as 48%. Rice yield was highest in CSA 70% plot as 102% compared to conventional plot.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.4
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• pp.334-341
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• 1992

The effects of the various pattern of paddy-upland switching system on rice yield and the nutrient absorption characteristics were examined in the paddy field of Seokcheon silty soil for three years from 1989 to 1991. The obtained results of the two years from 1990 to 1991 are as follows : 1. Rice grain yields were high in the order of potato-cabbage>soybean>continuous paddy plot for the second and third year. Among the rice yield components the numbers of grains per panicle and the rate of ripening grain exerted the yield increase. 2. The contents and absorption amounts of nutrient in harvested straw plant increased with the incease of rice yields during the second and third year(1990~1991). The amounts of all nutrient absorption increased with the increased level of nitrogen fertilization at the third year(1991). 3. The periodical change of leaf green color was responded well with the content of ammonia concentration of soil solution.

• Journal of Environmental Health Sciences
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• v.43 no.3
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• pp.194-201
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• 2017

Objectives: Zinc oxide nanoparticles (ZnO NPs) are widely used in various commercial products, but they are exposed to the environment and can induce toxicity. In this study, we investigated the environmental fate and bioaccumulation of ZnO NPs in a microcosm. Methods: The microcosm was composed of water, soil (Lufa Soil 2.2) and organisms (Oryzias latipes, Neocaridina denticulata, Semisulcospira libertina). Point five and 5 mg/L of ZnO NPs were exposed in the microcosm for 14 days. Total Zn concentrations were measured using an Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and intracellular NPs were observed using Transmission Electron Microscopy (TEM). Results: In the initial stages of exposure, the Zn concentrations in water increased in all exposure groups and then decreased, while the Zn concentration in soil increased after three hours for the 5 mg/L solution. Zn concentrations also showed increasing trends in N. denticulata and S. libertina at 0.5 and 5 mg/L, and in O. latipes at 5 mg/L. Accumulation of NPs was found in the livers of O. latipes and hepatopancreas of N. denticulata and S. libertina. Conclusions: In the early stages of exposure, ZnO NPs remained in the water, and then were transported to the soil and test species. Unlike other species, total Zn concentrations in N. denticulata and S. libertina increased for both 0.5 mg/L and 5 mg/L. Therefore, ZnO NPs were more easily accumulated in zoobenthos than in fish.

• Korean Journal of Environmental Agriculture
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• v.17 no.2
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• pp.122-126
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• 1998

This experiment was conducted to verify the responses of major crop species to saline stress.To determine the saline tolerance of crop species, sevral crop species were cultivated under sand-culture system using Hoagland's nutrient solution whit 200mM NaCl. The crop species showing saline tolerance were cotton(Gossypium indicum), maize(Zea mays), barely(Hordeum vulgare), and wheat(Triticum aestivum) but perilla (Perilla frutescens) and leguminous crops, mung bean(Phaseolus radiatus), azuki bean(Phaseolus angularis) and soy bean(Glycin max) showed very por tolerance. One the typical symptom was the darkening of leaf color due to increase of chlorophyll concentration.Among of the plant families, Fabaceae was the most susceptible but crop species belonging to Poaceae were more proper for cultivating on reclaimed tidal land in the course of desalinazation. It was suggrsted that the crop species belonging to Fabaceae, a sensitive family to soil salinity, must be cultivated when the soil salinity decreased below 10ds/m. To know the critical salinity level for crop growth,salinity of saline soil collected from reclaimed tidal land was adjusted from 10.0ds/m tp41.7ds/m with tap water. It was suggested that the ECs of the soil in which the plant height of each crop spicies was reduced to 50% of control plant were 22.6 and 21.7 ds/m in rice, barley, corn, mung bean, and soy bean,respectively.

• Journal of the Korean Geotechnical Society
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• v.40 no.3
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• pp.55-63
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• 2024

Xanthan gum biopolymer is an ecofriendly ground stabilizer that maintains stability in a wide range of temperatures and pH values. The binding effect of sandy soil particles realized by injecting xanthan gum biopolymer is dependent on the xanthan gum matrix, which is formed during the drying process; thus a study on the effects of the drying process of the xanthan gum solution on the changes in stiffness characteristics of sandy soil is required. In this study, shear wave velocity and electrical resistivity were monitored in sandy soil specimens saturated with biopolymer solutions of different gravimetric concentrations to investigate the improvement effects of biopolymer-treated sandy soils with the drying process. The experimental results reveal that both shear wave velocity and electrical resistivity increase during drying process. The results demonstrate the stiffness improvement effects of biopolymer-treated sandy soils. In addition, a higher stiffness improvement effect was monitored in the biopolymer-treated sandy soils with a higher gravimetric concentration. The results of this study may be used to estimate the stiffness improvement effects of sandy soils treated with biopolymer solutions with the drying process.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.188-188
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• 2017

Rice (Oryza sativa L.) is one of the major crops that is seriously impacted by global soil salinization. Rice is among those crops where most of the high-yielding cultivars are highly sensitive to salinity. The key to a plant survival under NaCl salt stress is by maintaining a high $K^+/Na^+$ ratio in its cells. Selection for salinity tolerance genotypes of rice based on phenotypic performance alone is less reliable and will delay in progress in breeding. Recent advent of molecular markers, microsatellites or simple sequence repeats (SSRs) were used to find out salt tolerant rice genotypes. In the current experiment phenotyping and genotyping studies were correlated to differentiate different rice accessions for salinity tolerance. Eight rice accessions along with check plant Dongjin were screened by physiological studies using Yoshida solution with 50mM NaCl stress condition. The physiology studies identified four tolerant and four susceptible accessions based on their potassium concentration, sodium concentration, $K^+/Na^+$ ratio and biomass. 17 SSR markers were used to evaluate these rice accessions for salt tolerance out of which five molecular markers were able to discriminate tolerant accessions from the susceptible accessions. Banding pattern of the accessions was scored comparing to the banding pattern of Dongjin. The study identifies accessions based on their association of $K^+/Na^+$ ratio with molecular markers which is very reliable. These markers identified can play a significant role in screening large set of rice accessions for salt tolerance; these markers can be utilized to improve salt tolerance of commercial rice varieties with marker-assisted selection (MAS) approach.

• Korean Journal of Organic Agriculture
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• v.18 no.4
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• pp.549-557
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• 2010

This study was established on which germanium (Ge), known as one of the functional nutrients, treatment is the most effective method for increasing Ge uptake and contributing flowering development in the pruned branches in the winter. Ge treatment included foliar application, soil fertigation, trunk injection, and the three-combined application. Ge concentration in the pruned branches was greater on the three-combined treated trees, and Ge treated branches had greater Ge concentrations than the control. Pruned branches grown in the solution culture had greater bud weight and bud scale number on the Ge treated trees than the control. Ge treatments increased flowering per branch and flower number per bud as well as improved resistance of the freezing temperature damage. Overall, there were no consistent results of all the variables by the Ge application methods.