• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.09a
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• pp.37-47
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• 2004

In Korea, over three hundreds of the coal mines were closed or abandoned due to the depression of the mining industry since the late 1980s. Many of them locate in the steep mountain valleys and the coal mine wastes had been disposed without a proper treatment From these mines, enormous amounts of coal mine overburdens have been abandoned in the slopes and the ample amounts of acid mine drainage (AMD) from either portal or overburdens have been discharging directly to the streams, causing the detrimental effects on soil and water qualities. Objectives of this research were to reclaim the coal mine overburdens using the lime waste cake from the soda ash production by stabilizing the overburden slopes, introducing the vegetation alleviate the environmental problems caused by the closed coal mines. The percentages of the grass distribution ratio (%) and the surface coverage ($\textrm{cm}^2$) in each treatment plot were determined during June to August after seed spraying grasses such as orchard grass (Dactylis glomerata L), Kentucky Bluegrass (Poa pratensis L.) and Eulalia (Miscanthus sinensis Anderss) at the end of May. The grasses covered only 15.5 % of the coal overburden plot at the early stage but the coverage was increased with time to 33% in August. Growth of such grasses was enhanced with the combined treatments of lime waste and topsoil resulting in the increased surface coverage by the grasses. The Increment of the surface coverage from June to August was higher with lime waste treatments. The distribution percentages and surface coverage were highest when the lime wastes were treated at 25 % of the lime requirement. This might be related with the high salt contents in the hire wastes. Results demonstrated that the amounts of lime wastes at 25% of the lime requirement were sufficient for neutralizing the acidic coal overburden and introducing the re-vegetation. Either layering between the coal waste and topsoil or mixing with coal overburdens could be adopted as the lime waste treatment method. The combined treatment of lime wastes and topsoil was recommended for re-vegetation in the coal overburden slopes. The lime wastes from the soda ash production might have a potential to be recycled for the reclamation of the abandoned coal mines to alleviate the environmental problems associated with coal mine waste.

• Economic and Environmental Geology
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• v.51 no.5
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• pp.429-438
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• 2018

Since concrete is a hardened aggregates of various materials, it needs to be crushed for chemical analyses. However, the effect of sample crushing on the analytical results has not been precisely assessed till today. In this study, we prepared concrete test pieces using Portand cements and fly ashes as binding materials, and ponded ashes and sands as aggregates and analyzed the heavy metals of the test pieces using Standards for Fair Testing of Soil Contamination (SFTSC) and Wastes (SFTW). For this, each test piece was partially crushed at first and sieved for separation of grains of <0.15 mm, 0.15-0.5 mm, and 0.5-5 mm from the same crushed samples (Crushing Method I). Results of those samples using SFTSC showed a clear trend that analyzed heavy metal concentrations are higher in the finer fractions. Particularly, fractions with <0.15 mm indicated much higher concentrations than the theoretical ones, which were calculated based on the concentrations of individual materials and their mixing fractions. In contrast, the analytical results were generally comparable with the theoretical ones when the test pieces were totally pulverized such that all the crushed grains were <0.15 mm in size (Crushing Method II). These results are associated with the fact that cement materials and fly ashes, which are high in heavy metals relative to other materials, are enriched in the fine fractions. The analytical results using the SFTW derived very low concentrations in most of parameters and did not indicate the dependence of concentrations on the crushing methods due to using distilled water as leaching agent.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.4
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• pp.239-246
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• 2008

This research tried to find out the optimum fabrication method of calcined clay granules comprising zeolite. Kaolin clay and natural zeolite powder were used as raw materials of calcined clay, and silica stone powder was used for controlling the porosity of the granules. The granulation was performed with two kinds of granulators: a pan granulator and a high-shear mixer granulator. Various granules were fabricated by the mixing ratios and the rotation speeds of the granulators, and were heated from 400 to $700^{\circ}C$ at $100^{\circ}C$ interval. The crushing strength, pore size distribution, and CEC of the granules were measured. The evaluation method for the resistance of granules to human treading was created and the tests were conducted at dry and wet conditions. The resistance and crushing strength improved in proportion to the rotation speed of the granulator and the heating temperature, but the CEC decreased. The pellet made by the pan granulator did not have the strength against treading upon heating to below $700^{\circ}C$, but the pellet made by the high-shear mixer granulator endured the treading test upon heating to over $500^{\circ}C$

• Korean Journal of Soil Science and Fertilizer
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• v.44 no.3
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• pp.321-330
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• 2011

The physical properties of horticultural substrate are important for optimal plant growth. The physical properties should be properly maintained during the crop growing season for producing higher yield. This experiment was carried out to evaluate the physical properties of different mixtures from various raw materials as horticultural substrates. The mixtures at the different ratios of peatmoss, perlite and vermiculite subjected to 10:0:0, 8:2:0, 6:4:0, 4:6:0, 2:8:0, 0:8:2, 0:10:0, 0:6:4, 0:4:6, 0:2:8, 8:0:2, 0:0:10, 6:0:4, 4:0:6, 2:0:8, 2:6:2, 2:4:4, 4:2:4, 4:4:2, 6:2:2 and 2:2:6 were prepared and analyzed according to two methods of the European Standardization (EN) and Rural Development Administration (RDA). The optimum range of physical properties of a specific horticultural substrate can be predicted using physical-property-triangle. This triangle can also be used to convert a physical property from the EN method to that from the RDA method. Results showed that the mixture at a ratio of > 60% peatmoss, in most cases, is in the range of optimum physical condition for plant growth. We conclude that the developed physical-property-triangle can be suitable to suggest the optimum ratios of horticultural substrates used in this study.

• Korean Journal of Soil Science and Fertilizer
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• v.40 no.5
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• pp.369-376
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• 2007

This experiment was carried out to investigate optimum conditions of coir-based substrates for the red pepper plug seedlings. Eleven different coir based substrates prepared by mixing of coir, vermiculite, rice hull, perlite, zeolite, mixed at different ratios were tested. The physical and chemical properties of the substrates were analyzed by the CEN (European committee for standardization) method. Fresh and dry weights of shoot and root, leaf area, root length, and T/R ratio (dry shoot weight/dry root weight) were determined at 55 days after sowing. The results showed that the growing media CRZ 8(coir:rice hull: vermiculite=8:1.9:0.1) and CVSZ 6(coir:silver vermiculite: zeolite=6:3.9:0.1) can successfully be used for pepper plug seedlings judging from dry weight and T/R ratio of the plug seedlings. The optimal range of total pore space, water volume, air volume, easily available water content and water buffering capacity of the coir-based growing substrates for pepper plug seedlings were in the range of 92~94%, 52~60%, 32~43%, 18~21%, and 0.9~8%, respectively.

• Journal of the Korean GEO-environmental Society
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• v.24 no.1
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• pp.15-23
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• 2023

The grouting method is a method of construction for the purpose of waterproofing and reinforcing soft ground. When grout is injected into the ground, there are various types of penetration and diffusion of grout depending on the shape of the ground, the size of soil, the porosity, and the presence or absence of groundwater. the current situation. Therefore, in this study, to investigate the penetration performance of the grouting to conductive material, laboratory tests were performed on the addition of the conductive material. In the injection test, 0%, 3%, and 5% of the mixed water were added as conductive materials to the grout, and the original ground condition was composed of various types of ground composed of gravel and silica sand. Conductive grout is injected by pressure into the model ground using a dedicated injection device, and the injection time (t), pressure (p), flow rate (v) and injection amount (q) are measured, and the hardened body injected in the model ground is collected. Penetration performance was evaluated. In the results of the grout injection experiment, the amount of conductive material used and the grout injection rate showed an inverse relationship, and it was confirmed that the penetration pattern was changed according to the size of the soil particles in the model ground. The grout containing the conductive material has relatively good penetration into the ground and excellent strength and durability of the hardened body, so it was judged that it could be used as an additive for measuring the penetration range of the grout.

• Journal of the Korean GEO-environmental Society
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• v.13 no.1
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• pp.5-13
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• 2012

For the last decade the amount of waste has rapidly been increased in South Korea and many waste landfills have been built according to government guidelines specifying required systems such as landfill liner, leachate collecting facilities, final cover system, etc. This effort has led the recently constructed landfills to be under well managed sanitary condition. In a meanwhile closed waste-landfill sites in the past before the adoption of the government guidelines exits under unsanitary condition. In these cases untreated leachate flew out to the surroundings due to the absence of liner and leachate collecting facilities and caused groundwater and soils to be contaminated. Waste generated odor and gas also brought civil complaints. Because environmental influences bring serious problems nearby sites, it is required to have unsanitary waste-landfills to be appropriately treated and managed. A study to evaluate environmental influence and contamination level of surroundings nearby and on the unsanitary landfills is necessary before the establishment of "Management guide of closed landfill site." This paper presents an environmental evaluation for the closed site, Doil-dong landfill, according to "Closed landfill management regulation" by Ministry of Environment. "D" landfill, located in Pyeongtaek city, has possobility to contaminate surrounding surfacewater and groundwater by leakage of leachate. The in-situ stabilization carried out to build the DMW(deep soil mixing cutoff wall) wall and drainage systems.

• Journal of Korean Society on Water Environment
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• v.21 no.4
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• pp.347-352
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• 2005

The isolated microorganisms, Pseudomonas stutzeri, Raoultella planticola (Klebsiella), Serratia fonticola from petroleum contaminated soil were enriched on benzene, toluene, ethylbenzene, o-xylene as carbon and energy sources, respectively. And the degradation characteristics of BTEX was observed in the mixed BTEX substrates. We found that the BTEX in mixed substrates were degraded more than 50% by three isolated microorganisms. Among three isolated microorganisms, the highest degradation rate was observed in Pseudomonas stutzeri, but the degradation rate was different according to microorganisms. In order to increase the degradation efficiency, we applied the co-culture of isolated three microorganisms. The mixture rate of pseudomonas stutzeri : Raoultella planticola (Klebsiella) : Serratia fonticola was follows ; 1:2:1, 1:1:2, and 2:1:1, respectively. In two co-culture of 1:2:1 and 1:1:2, degradation rate was lower than isolated microorganisms. However, degradation rate became higher than isolated microorganisms and the degradation rate of benzene, toluene, and ethylene was more than 95% in co-culture of 2:1:1. The degradation rate increased through the co-culture of isolated microorganisms, however, the growth rate decreased. This was resulted from the substrate competition between microorganisms. The co-culture of microorganisms is a effective method to increase the degradation efficiency of BTEX and the co-culture mixing rate is a important factor for determination of degradation efficiency.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.44 no.3
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• pp.225-229
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• 1999

Unstable seedling stand establishment of wet direct seeding culture of rice is one of the major elements preventing the extension of its culture area. In order to develop methods of seedling stand improvement in direct seeded rice on flooded surfaces, three field experiments were conducted on silty loam soil using a cultivar 'Donjinbyeo' for three years, mainly focusing on water management after seeding and seed soaking with plant growth regulators (PGRs). Under the condition of shallow flooding after seeding, seedling stand rate increased and floating seedling rate decreased in both early and normal season seeding compared to deep flooding. With earlier draining time after seeding, there was a tendency towards preferential growth of the seminal root, increase of seedling stand and decrease of the floating seedling rate. Therefore the highest seedling numbers per unit area and the lowest floating seedling numbers were found upon drainage at 1 day after seeding (DAS), while a contrary tendency was shown upon conventional drainage at 7 DAS. Seed soaking with PGRs such as Metalaxyl or mixing of Metalaxyl with gibberellic acid (GA$_3$) significantly increased the seedling stand. In addition the effects of PGR treatment on seedling stand and the early growth of plants were greater under flooded conditions than under drained conditions after seeding, although draining of water after seeding improved the seedling establishment rate more when compared with the PGR treatment. These results suggest that draining management after seeding or maintaining of shallow flooding for a week is the most effective method to improve the seedling stand rate in wet direct seeding.

• The Journal of Engineering Geology
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• v.30 no.2
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• pp.131-145
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• 2020

The construction on these flimsy ground, activation of unsymmetrical surcharges, can often cause of the embankment road lateral flow or the destruction of the activities. In this study, the stability of the abutment pile foundation installed on soft ground and its behavior has been evaluated. The behavior of the abutment pile foundation under lateral flow was studied by verifying the behavior and reinforcement effects of the abutment pile foundation of previous studies about horizontal loads acting on the pile due to the lateral flow of the ground by performing finite element analysis. As a result of the consolidation analyses, the undrained cohesion or the strength of the soft ground, was increased by about 1.1 to 1.8 times by the increase in the strength of the soft ground according to the degree of consolidation. It is deemed reasonable to use 3.8 cm of the allowable displacement both economically and constructively, but considering the importance of the structure and the uncertainty of the ground, measurement shall be carried out during construction and thorough safety management of the lateral flow should be done.