• Economic and Environmental Geology
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• v.57 no.2
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• pp.185-204
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• 2024

This study was conducted for evaluation the geological, physical, and chemical properties of domestic sand by analyzing about 4,800 quality data of natural sand from river and land area surveyed until 2023 through the aggregate resource survey conducted by the Ministry of Land, Infrastructure and Transport. The average depth of the Quaternary unconsolidated sedimentary layer in Korea, which includes a sand layer, is about 10m (maximum depth 66m). The thickness of the sand layer within the sedimentary layer is most dominant in the range of 0.5m to 4.0m. This accounts for about 70% of the entire sand layer. In the sand layer, the ratio of sand, gravel, and clay is 60:20:10. Regardless of the provenance or geology, the sand is mainly composed of quartz, plagioclase, and K-feldspar, and the minor minerals are muscovite, biotite, chlorite, magnetite, epidote. The sand includes in 45~75% of quartz, 5~20% of plagioclase and K-feldspar, each other. And other minor minerals are included in 10%. The average grain size of sand is 0.5mm to 1.0mm, which accounts for 44% of sand samples. The water absorption rate and soundness are estimated to be suitable for aggregate quality standard in almost all sand, and the absolute dry density is suitable for 66%.

• The Korean Journal of Quaternary Research
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• v.34 no.1
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• pp.41-51
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• 2024

The Sincheon wetland shows a remarkable diversity of fluvial landforms, such as river islands, anastomosing channels, braided channels, and sand-gravel bars, which contribute to its rich ecological habitat. The wetland area is characterized by a ecological diversity of herbaceous and woody plants. Significant changes in land cover within the wetlands were observed from 2008 to 2020. Notably, there was a rapid decrease in agricultural area from 18% to 0.04%, while the vegetation area expanded from 45% to 54%. Concurrently, the water area also experienced a notable increase from 34% to 41%. The surface sediment composition in the studied area displays sandy loam characteristics and exhibits acidic soil properties. Sediment acidity tends to increase downstream and in the central part of channels. Variations in acidity are also observed at nearby collection sites due to the tributaries and local discharge. The presence of dense vegetation in river islands and bars has led to a significant transformation of sediments into soil, with this change being more pronounced downstream, particularly near the weirs. The installation of a weir in Sincheon wetland is believed to have a significant impact on altering flow velocities between upstream and downstream sections, as well as influencing erosion and sediment deposition patterns. However, given the formation of landforms in response to weirs, effective administration and management are essential to address potential risks of catastrophic environmental disruptions, such as the removal of weirs and/or the maintenance of river channels.

• Food Science and Preservation
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• v.30 no.5
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• pp.811-821
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• 2023

This study investigated the storability of onions according to manual and mechanical harvesting. Moreover, we simulated the onion-to-onion impact during the mechanical harvesting process and investigated the storability after artificially subjecting the onions to impact treatment. The onion harvesting methods included hand plucking + manual collection, digger + manual, and digger + mechanical collection. The maximum impact height during the mechanical harvesting process was 0.5 m. Immediately after harvesting, no significant difference in the bruise and wound rate among the harvesting methods was observed. Any increased bruise or wound rate because of mechanical harvesting was presumed to be influenced by soil conditions, such as the presence of gravel, and machine operation factors. Furthermore, the storability during the 8.5 months storage showed no significant difference according to the harvesting methods. In treatments by simulating the impacts during the mechanical harvesting process, the impact heights were 0.0 m (0.0 J), 0.25 m (0.86 J), 0.5 m (1.72 J), and 0.75 m (2.57 J), each performed once, and four times at the same position (3.43 J) and four times at different positions (3.43 J) at 0.25 m. Throughout all the treatments, there were no significant differences in the storability during the 8.5 months storage period.

• Applied Biological Chemistry
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• v.11
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• pp.151-166
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• 1969

I. Fffects of nitrogen supplying level and culture condition on the top growth aod tubers formation of Ipomoea Batatas. 1) The low level nitrogen (A plot) 3 Milliequivalent per liter of nutrient solution stimulated tuber formation while the high level nitrogen ($B_1\;and\;B_2$ plot) of 10 milliequivalent per liter failed to form tuber though fibrous roots were seen much activated. The suppressive effect of nitrogen on tuber formation in presumed to result from the direct suppressive effect of nitrogen or a certain biocatalystic effect rather than from any indirect effect through the stimulation to growth of tops or the competition with carbohydrates. 2) The addition of milligram urea to nutrient solution stimulated the growth and increased fresh weight and dry weight of the aerial part while suppressed, a little, plant length. 3) The water culture method, which this experiment newly adopted, stimulated plant growth more than the gravel Culture method. And the treatment of low level nitrogen (A plot) in this water culture also saw a considerable degree of tuber formation, as in the case of gravel culture. 4) The foliar application of growth retardant B-nine suppressed the plant length only, with no other recognizable effect. II. Fffects of urea supplying level on the growth of IPOMOEA BATATAS. 1) The higher level of urea which was absorbed tby roots through nutrient solution suppressed top growth, such as plant length, number of leaves and fresh weight. And this can be attributed to the direct absorption of urea which was not ammonificated. 2) Although the higher level of nitrate nitrogen (B plot) made no tuber formation in previous experiment (Report-1), the higher level of urea nitrogen (A plot) made tuber formation possible in this experiment. The ratio of tuber to top was, however, less in higher level of urea than in lower level of urea, and the suppressing effect was larger on tuber than on top. 3) The foliar application of urea stimulated top growth while the higher level of urea absorbed by roots suppressed it, though the amounts of urea supplied in two experiments were same. Ratio of top to roots was larger in foliar application of urea (C plot) and less in root absorption of urea both of higher (B plot) and lower urea levels (A plot). III. Fffects of growth retardant etc. on the growth of IPOMOEA BATATAS in relation to urea application. 1) B-nine (N-dimethyl amino-succinamic acid) is recognized as a growth retardant, suppressed the plant length irrespective of urea levels. The treatment of gibberellin stimulated distinctly plant length, and the combined treatment of gibberellin and B-nine recovered completely the plant length which had been suppressed by B-nine. 2) B-nine increased fresh weight, especially, fresh weight of top both in lower and higher level of The degree of fresh weight increase varied according to concentrations of B-nine, of which the 0.15% of B-nine ($B_1$ plot) was the effective in higher level of urea. The effect of B-nine for increasing fresh weight was the largest in top next in tuber, and the least in fibrous roots. The ratio of fibrous roots to top was always decreased by B-nine application, which the ratio of tuber to top was contrary increased by B-nine in higher level of urea though decreased in lower level of urea. 3) Gibberellin treatment also increased fresh weight but the combined treatment ($B_3$+GA plot) of gibberellin and B-nine was even more effective than any of single treatments. Gibberellin and B-nine proved to be synergistic with fresh weight while reverse with plant length. 4) Considerable influences were abserved mainly in the length of plants and their fresh weight after B-nine treatment. So that B-nine may be reguraded as a metabolic controller rather than as an antimetabolite. 5) The surpressed growth of plants cause by higher level of urea was normalized by B-nine treatment. This fact suggested a further study on the applicability for practical use.

• Korean Journal of Ichthyology
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• v.24 no.3
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• pp.183-190
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• 2012

The spawning site characters in the natural environment of bull-head torrent catfish, Liobagrus obesus, were investigated at the part of the Gosan stream in Korea from April to October 2010 and June 2011. The sex ratio of female to male was 1 : 1.02. Spawning season was from June to July with water temperature in approximately $23^{\circ}C$. The spawning sites were covered by the boulder used upper plate and were composed of gravel and sand. One male lies with the egg mass and guards the developing embryos in the hollow below the boulder. The environmental conditions of the spawning sites were $61.4{\pm}11.97$ (50~85) cm in depth, 0.58${\pm}0.067$ (0.48~0.72) m/sec in surface water velocity, $0.46{\pm}0.098$ (0.27~0.61) m/sec in middle water velocity, $0.27{\pm}0.083$ (0.14~0.41) m/sec in bottom water velocity. The boulder width as spawning sites was $26.2{\pm}5.32$ (20~38) cm in long axis, $20.5{\pm}2.97$ (16~25) cm in short axis and $11.1{\pm}4.02$ (5~19) cm in height. The hollow underneath the boulder was $9.8{\pm}2.32$ (6~14) cm in diameter and $2.8{\pm}1.10$ (1.5~5) cm in depth. The average number of eggs in ovary was $124{\pm}27.7$ (92~180). The matured egg size was $3.40{\pm}0.078$ (3.21~3.56) mm. The average number of spawning eggs in the spawning site was $99{\pm}12.9$ (81~122).

• Journal of the Korean Institute of Landscape Architecture
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• v.43 no.3
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• pp.77-91
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• 2015

This study aims to suggest adequate soil management through the analysis of physicochemical properties of soil in the planting grounds of Incheon International Airport, which was constructed on a massive land reclamation site. Study areas were 5 sites at the international business complex, the passenger terminal, the airport support complex, the free trade zone, and the access road. Soil profile analysis showed that 9 plots out of the 27 plots were hardpan and heterospere within 80cm from the soil surface. The earth laid on the ground was categorized as gravel based soil(4 plots), dredged soil from the sea bottom and mixed reclamation materials(2 plots), clay with poor permeability(3 plots) and waste construction material(1 plot). Average soil hardness was $11.5kg/cm^2$ and soil textures were sandy soil, sandy loam and loamy sand. Average soil pH was 6.7 and average organic matter content was 0.7%. Electrical conductivity was 0.0dS/m and exchangeable cation concentrations were $Ca^{2+}$ 3.4cmol/kg, $Mg^{2+}$ 1.5cmol/kg, $K^+$ 0.3cmol/kg and $Na^+$ 1.0cmol/kg. Average cation exchange capacity was 11.0cmol/kg. Although average figures in Solum mostly meet the landscape design criteria, properties of each soil layer showed various values sometimes over the limit. Base saturations were $Ca^{2+}$ 29.9%, $Mg^{2+}$ 13.3% and $K^+$ 3.7% for lower soil, $Ca^{2+}$ 33.3%, $Mg^{2+}$ 17.0% and $K^+$ 2.7% for mid-soil and $Ca^{2+}$ 32.6%, $Mg^{2+}$ 12.2% and $K^+$ 1.9% for upper soil. Exchangeable sodium percentages were 16.4% for lower soil, 7.5% for mid-soil and 4.7% upper soil. Sodium adsorption rates were 0.8 for lower soil, 0.3 for mid-soil and 0.2 for upper soil. Factors affecting to the vegetation growth were heterogeneity and poorness of solum, disturbance of dredged soils, high soil hardness including hardpan in the subsurface soil layer and shallow effective soil depth, high soil acidity, imbalance of base contents, low organic matter content and low available phosphate levels in the soil.

• Journal of Wetlands Research
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• v.17 no.3
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• pp.228-236
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• 2015

Urbanization causes many environmental, hydrological and ecological problems such as distortion of the natural water circulation system, increase in nonpoint source pollutants in stormwater runoff, degradation of surface water quality, and damage to the ecosystem. Due to the increase in impervious surface by urbanization, developed countries apply low impact development (LID) techniques as important alternatives to reduce the impacts of urbanization. In Korea, LID techniques were employed since 2012 in order to manage nonpoint source pollutants. LID technology is a technique for removing pollutants using a variety of physical, chemical and biological mechanisms in plants, microorganisms and filter media with the reduced effluence of stormwater runoff by mimicking natural water circulation system. These LID facilities are used in a variety of filter media, but an assessment has not been carried out for the comprehensive comparison evaluation of adsorption and desorption characteristics for the pollutant removal capacity. Therefore, this study was conducted to analyze the adsorption and desorption characteristics of various filter media used in the LID facilities such as sand, gravel, bioceramic, wood chips and bottom ash etc. in reducing heavy metals(Pb, Cu). In this study, the adsorption affinity for Pb in all filter media was higher than Cu. Pseudo second order equation and Langmuir-3 isotherm are more applicable in the adsorption kinetic model and adsorption isotherm model, respectively. As a result of the desorption experiment, the filter media does not exceed KSLT which is the hazardous substance leaching limit, showing the capability of the filter media in LID. The bioceramic and woodchip as filter medias were evaluated and exhibited excellent adsorption capacity for Pb.

• The Journal of Engineering Geology
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• v.28 no.1
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• pp.101-115
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• 2018

This study was carried out to evaluate the effects of various filter conditions on unconfined aquifer (alluvial aquifer). We made model test device which has filter layer, pumping well and observation well which consist of sand layer and gravel layer to test. Step drawdown test and long term pumping tests were carried out using the device. The permeability characteristics of each test group were confirmed and the optimal yield was calculated. As a result of comparing the optimal yield of double filter and single filter in sand, dual-filter SD-300 was valued at 216.8 % higher final optimal yield than single-filter SS-300. Comparing the dual filter SD-300 and the single filter SS-100 with a thin filter layer, dual-filter SD-300 was valued at 709.2% higher final optimal yield than single-filter SS-300. As a result of analysis of optimal yield change over time, It was confirmed that the ratio of optimal yield of single filter and dual filter increase over time. In order to evaluate the long-term change in water intake efficiency, we considered the point at which the initial optimal yield was reduced by 50%. The dual filter SD-300 is about 351.1% higher than SS-300, which is the same thickness filter, and about 579.0% higher than SS-100. From these results, Assuming that the point at which the initial quantity of water intake is reduced to 50% is the well life, double filters are expected to increase their lifespan by about 3.5 times over single filters of the same thickness and by about 5.8 times over typical single filter. These results can be used to design wells to river bank filtration or filtered seawater. In addition, it is possible to clarify the effect of the double filter through the comparison with the future field test results.

• Economic and Environmental Geology
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• v.51 no.5
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• pp.401-407
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• 2018

For the treatment of heavy metals in the mine drainage from the closed mine area, various methods such as passive, active and semi-active treatments are considered. Among contaminated elements in the mine drainage, Mn is one of the difficult elements for the treatment because it needs high pH over 9.0 for its concentration to be reduced. In this study, the efficiency of various slag complex reactors (slag (S), slag+limestone (SL) and slag+Mn coated gravel (SG)) on Mn removal in the presence of Fe, which is a competitive element with Mn, was evaluated to investigate effective methods for the treatment of Mn in mine drainage. As a result of experiments on Mn removal without Fe during 358 days, using influent with $30{\sim}50Mn{\cdot}mg/L$ and pH 6.7 on the average, S reactor showed continuously high Mn removal efficiency with the average of 99.9% with pH 8.9~11.4. Using the same reactors, Mn removal experiments with Fe during 237 days were conducted with the influent with $40{\sim}60Mn{\cdot}mg/L$. The pH range of effluent reached to 6.1~10.0, which is slightly lower than that of effluent without Fe. S reactor showed the highest range of pH with 7.1~9.9, followed by S+L and S+G reactor. However, the efficiency of Mn removal showed S+L>S>S+G with the range of 94~100%, 68~100% and 68~100%, respectively in spite of relatively low pH range. S+L reactor showed the most resistance on Fe input, which means other mechanisms such as $MnCO_3$ formation by the carbonate prouced from the limestone or autocatalysis reaction of Mn contributed to Mn removal rather than pH related mechanisms. The evidence of reactions between carbonates and Mn, rhodochrosite ($MnCO_3$), was found from the X-ray diffraction analysis of precipitates sample from S+L reactor. From this study, the most effective reactors on Mn removal in the presence of Fe was S+L reactor. The results are expected to be applied for the Mn containing mine water treatment in the presence of Fe within the relatively low range of pH.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.696-704
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• 2010

The objective of this study was analysis of two methods of land suitability classification for wild edible green. One method was Maximum limiting factor method (MLFM) and the other was Multi-regression method (MRM) for land suitability classification for wild edible green. The investigation was carried out in Pyeongchang, Hongcheong, Hoeingseong, and Yanggu regions in Korea. The obtained results showed that factors related to the decision classification of the land suitability for wild edible green cultivation were land slope, altitude, soil morphology and gravel contents so on. The classification of the best suitability soil for wild edible greens were fine loamy (silty), valley or fan of soil morphology, well drainage class, B-slope (2~7%), available soil depth deeper than 100cm, and altitude higher than 501m. Contribution of soil that influence to crop yields using Multi-regression method were slope 0.30, altitude 0.22, soil morphology 0.13, drainage classes 0.09, available soil depth 0.07, and soil texture 0.01 orders. Using MLFM, area of best suitable land was 0.2%, suitable soil 15.0%, possible soil 16.7%, and low productive soil 68.0% in Hongcheon region of Gangwon province. But, area of best suitable land was 35.1%, suitable soil 30.7%, possible soil 10.3%, and low productive soil 23.9% by MRM. There was big difference of suitable soil area between two methods (MLFM and MRM). When decision classificatin of the land suitability for wild edible green cultivation should consider enough analysis methods. Furthermore, to establishment of land suitability classification for crop would be better use MRM than MLFM.