• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.987-997
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• 2008

Successful design, construction and maintenance of geotechnical structure in soft ground and marine clay demands prediction, control, stability estimation and monitoring of settlement with high accuracy. It is important to predict and to estimate the compression index of soil for predicting of ground settlement. Lab. and field tests have been and are indispensable tools to achieve this goal. In this paper, Artificial Neural Networks (ANNs) model with Levenberg-Marquardt Algorithm and field database were used to predict compression index of soil in Korea. Based on soil property database obtained from more than 1800 consolidation tests from soils samples, the ANNs model were proposed in this study to estimate the compression index, using multiple soil properties. The compression index from the proposed ANN models including multiple soil parameters were then compared with those from the existing empirical equations.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.4
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• pp.1-7
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• 2003

Artificial ground greening, which is considered as a way for the greening of cities, should be constructed easily and maintained continuously. Thus it is necessary to use light soils for keeping in flexible formation and light load. And the garden should be managed optimally taking account for the characteristics of the soil and plant. But in most landscape green area, they are not under management. Mostly they are occasionally irrigated without nutrient by hand-operating. So this study was conducted to investigate plant growth by management methods and soil depth(15cm, 30cm). As a results of the different methods of management had effect on the plant growth and on the rate of flowering. When Hosta longipes were grown in different three management methods, control(rainfall), periodical irrigation, and nutri-irrigation(fertigation), the content of chlorophyll, the plant growth and the rate of flowering were higher in nutri-irrigation (fertigation) treatment than those in control(rainfall) and periodic irrigation. And nutrient contents of leaf are also higher. Between 15cm and 30cm soil depth, the plant growth of 15cm soil depth is better than that of 30 soil depth. According to these results on artificial ground greening, determination of optimal soil depth by plant species is required, And a specialist for nutrient management is demanded.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.321-321
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• 2017

Water availability in rainfed lowlands (RFL) is strongly affected by climate change. In RFL, rice plants are exposed to soil moisture fluctuations (SMF) but rarely to simple progressive drought as widely believed. Typical RFL field is characterized by a about 5-cm thick high bulk density hardpan layer underneath the cultivated layer at about 20 cm depth that impedes deep root development. Root system has the ability to develop in response to changes in SMF, known as phenotypic plasticity. We hypothesized that genotypes that can adapt to RFL have root plasticity. The roots can sharply respond to re-wetting after drought period and thus penetrate the hardpan layer when the hardpan is wet and so becomes relatively soft, and thus access water under the hardpan. This study aimed to identify CSSLs derived from a cross between Sasanishiki and Habataki which adapted to such RFL conditions. We used 39 CSSLs together with the parent Sasanishiki, which were grown in hydroponics and pot under transient soil moisture stresses (drought and then rewatering), and compared with continuously well-watered (WW) (control) up to 14 days after sowing (DAS), and 20 DAS, respectively. Based on the results of hydroponics and pot experiments, we selected a few lines, which were grown in the soil-filled rootbox with artificial hardpan layer and without artificial hardpan. For the rootbox without artificial hardpan, plants were grown under WW and transient soil moisture stresses for 49 DAS. While the rootbox with artificial hardpan, the plants were grown under WW (control) and SMF (WW up to 21 DAS, 1st drought (22-36 DAS), rewatering (37-44 DAS), and followed by 2nd drought (45-58 DAS)). Among the 39 CSSLs, only CSSL439 (SL39) consistently showed significantly higher shoot dry weight (SDW) than Sasanishiki under transient soil moisture stress conditions as well as SMF conditions in all the experiments. Furthermore, under WW, SL39 consistently showed no significant differences from Sasanishiki in shoot and root growth in most of traits examined. SL39 showed significantly greater total root length (TRL) than Sasanishiki under transient soil moisture stress, which is considered as phenotypic plasticity in response to rewatering after drought period. Such plastic root development was the key trait that effectively contributed to root elongation and branching during the rewatering period and consequently enhanced the root to penetrate hardpan layer when the soil penetration resistance at hardpan layer reduced. In addition, using the rootbox with artificial hardpan layer ($1.7g\;cm^{-3}$, heavily compacted), SL39 showed greater root system development than Sasanishiki under SMF, which was expressed in its significantly higher TRL, total nodal RL, and total lateral RL at hardpan layer as well as at below the hardpan layer. These results prove that SL39 has plasticity that enables its root systems to penetrate hardpan layer in response to rewatering. Under SMF, such root plasticity contributed to its higher gs and Pn.

• Journal of the Korea institute for structural maintenance and inspection
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• v.20 no.5
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• pp.85-92
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• 2016

The eight mixes and artificial soil aggregates were prepared for evaluating the practical application of lightweight foamed concrete as soil aggregates. The main parameter was unit binder content ranged between from 100 to $800kg/m^3$. In lightweight foamed concrete, flow, slurry and dried density, and compressive strength at different ages were measured. In Artificial soil aggregates crushed from lightweight foamed concrete, particle size distribution, pH, coefficient of permeability, cation exchange capacity(CEC), and ratio of carbon to nitrogen(ratio of C/N), were measured. The test results showed that flow, slurry and dried density, and compressive strength at different ages of lightweight foamed concrete increased with the increasing of unit binder content. Compressive strength at age of 28, of lightweight foamed concrete with unit binder of more than $500kg/m^3$, was more than 4 MPa. The ammonium phosphate immersion time of more than age of 3, was effective to decrease pH of artificial soil aggregates. In addition, artificial soil aggregates was evaluated as high class in terms of cation exchange capacity(CEC), while satisfied with value of ratio of carbon to nitrogen(ratio of C/N) recommended by landscape specification.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.28-44
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• 2015

Granite soil has been used traditionally as a school playground surface. Natural turf has also been used in some schools. Recently artificial turf has come into common use instead of granite soil or natural turf. Artificial turf playgrounds are used at 174 schools in Seoul, Korea. More than 3,500 artificial turf fields are installed in the United States. Because of the increase of artificial turf usage, there are many studies about the estimation of artificial turf effects to environment. Compared with artificial turf material effects such as characterization of substances released from material, and recognition of volatility of heavy metal into the surrounding environment - air or the percolating rainwater -, less studies for thermal effects of artificial turf playground have been done. Especially, the corresponding studies in Korea are few. Thus, the purpose of this research is to compare the thermal effects of artificial turf on school playground between natural turf and granite soil. In this study, air temperature and Predicted Mean Vote (PMV) were compared in three scenarios by Computational Fluid Dynamics (CFD) model. Additionally, the results were validated through a field measurement. Air temperature decreasing effects by natural turf are greater than those by artificial turf and granite soil at 14:30 on 20th, July 2011. It shows the same decreasing effects at 23:30. However, the difference is less than that of daytime. PMV differences between natural turf and the other two surface covers are large at daytime while those are much less at nighttime. Consequently, air temperature and PMV of artificial turf are the highest among three school playground surface pavements.

• Korean Journal of Environmental Agriculture
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• v.19 no.3
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• pp.234-241
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• 2000

For the recycling of sludge as soil conditioner, the firing technology in pottery industry was applied to the sludge treatment, and produced artificial media with many voids. To produce artificial media using sludge, chabazite and lime were used as additives, and the mixture of sludge and additives was thermally treated in the firing kiln at about $800{\sim}1,100^{\circ}C$ for about ten minutes. The effect of mixed artificial media into upland soil was investigated through the crop growth experiment and the physical & chemical characteristics of the mixed soils were analysed. The pH of artificial media was higher than that of the control soils. After the plant growth experiment, artificial media plots almost contained more CEC, OM, TN, TP and $AV.P_2O_5$ than upland soil plots. From the growth analysis, growth of soybean and corn in the artificial media plots was better than that in the original upland soil plots. The yield of soybean and corn in the artificial media plots were about 46kg/10a, 194kg/10a, respectively, which is higher than that in the control. Heavy metals in the artificial media plots were lower than the standard regulation. Therefore, the artificial media produced from sludge can be mixed into farmland, and crop production can be increased additionally.

• Geomechanics and Engineering
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• v.22 no.2
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• pp.153-163
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• 2020

Laboratory experiments were conducted with two different soil conditions to investigate rainfall infiltration characteristics. The soil layer materials that were tested were weathered granite soil and weathered gneiss soil. Artificial rainfall of 80 mm/hr was reproduced through the use of a rainfall device, and the volumetric water content and matric suction were measured. In the case of the granite soil, the saturation velocity and the moving direction of the wetting front were fast and upward, respectively, whereas in the case of the weathered gneiss soil, the velocity and direction were slow and downward, respectively. Rainfall penetrated and saturated from the bottom to the top as the hydraulic conductivity of the granite soil was higher than the infiltration capacity of the artificial rainfall. In contrast, as the hydraulic conductivity of the gneiss soil was lower than the infiltration capacity of the rainfall, ponding occurred on the surface: part of the rainfall first infiltrated, with the remaining rainfall subsequently flowing out. The unsaturated hydraulic conductivity function of weathered soils was determined and analyzed with matric suction and the effective degree of saturation.

• Proceedings of the Zoological Society Korea Conference
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• 1999.10b
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• pp.150.2-150
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• 1999

To investigate the weathering soil buffering capacities of the artificial acidic precipitation, the weathering soils and their leachate solutions were sampled from the host rocks(granite;GR, rhyolite;RH, gabbro;GA, basalt;BA, two serpentinite;SE1, SE2 and limestone;LI) and analyzed for pH and chemical properties. 1n the soil pH of the GR and RH ,the acidic rocks, were 5.02 and 5.95, respectively. And the GA and BA, basic rocks, were 6.52 and 7.57. The SE1 and SE2 were 8.90 and 8.89. While the LI was 7.84. These results means the typical soil pH properties by host rocks. After the artificial acidic precipitation input 5OOml, the average changes of soil leachate solutions treated by pH levels(pH 5.0, 4.0 and 3.0), were pH 5.73, 5.00 and 4.40. in GR soil, and pH 6.19, 5.99 and 5.57 in RH. GA were pH 6.31, 6.04 and 5.86, BA were pH 7.05, 6.85 and 6.56 and SE1 were pH 8.31, 8.26 and 7.71. SE2 were pH 8.29, 8.24 and 7.96. LI were pH 7.55, 7.46 and 6.79. The soil leachate pHs from volcanic rocks were higher than those from the plutonic rocks and GR soils showed greater response than other soils. With increasing 100ml input-solution, the soil leachate pHs were mainly decreased. Cation concentrations, CEC, EC and total nitrogen concentrations of RH and BA soils, the volcanic rocks, were higher than those of GR and GA soil, the plutonic rocks. On the contrary, Al concentrations of the GR and GA soils were higher than those of RH and BA soils, partly because of high quartz content in GR and Al content in the biotite and plagioclase in GA.

• Journal of the Korean Geosynthetics Society
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• v.14 no.3
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• pp.21-29
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• 2015

An artificial reef is a human-made underwater structure to improve marine environment and to provide a habitat for fish and other ocean wildlife. An artificial reef is placed on the ocean ground. In soft ground like most of the seabed soil, the ground has been settled due to weight of artificial reef. This study investigated the bearing capacity and settlement reduction effect of geosynthetics which were reinforced on the ground in a large size tank. Penetration tests and large soil tank laboratory tests were performed to investigate settlement reduction effect and bearing capacity on artificial reef with different spreading area of geogrid. Laboratory test results indicate that the spreaded geogrid under artificial reef reduce the settlement of ground and increase bearing capacity of ground.

• Korean Journal of Environment and Ecology
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• v.7 no.1
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• pp.10-21
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• 1993

Artificial acid rain (pH 3.0, 4.0 and 5.0) and ground was treated on the seeded pots of 4 species to examine its effects on germination and survival rate, seedling growth and contact angles on needle surface. Artificial acid rain was prepared by diluting sulfuric acid with ground water and ground water (pH 6.5) was used as control. Artificial acid rain was sprayed to seeded pots two or three times per week for growing season, one times per week for winter seasons. About 5mm of artificial acid rain was treated each time from early April, 1991 to early October, 1993. Germination and survival rate, soil acidity, seedling growth and contact angles on the needle surface were measured and compared among the treatments. The results were summarized as follows ; Artificial acid rain might have positive effects on growth-related characteristics of the seedlings in the first and second year of acid rain treatment, and the effects were differed among four species. All growth-related characteristics of the seedlings in third year, however, decreased with decrease of pH values of artificial acid rain. This was considered to the results of acidic accumulation over soil buffer capacity. Needle injury and biomass (defoliation) was correlated with the pH values of artificial acid rain, and this character might be a good criteria for early diagnosis of acid rain injury. The differences of soil acidity were significant among the treatments for all species. Contact angles between needle surface and water droplet decreased with decrease of pH values of artificial acid rain. Measuring and comparing contact angles might be very good criteria for early diagnosis of acid rain injury.