• Journal of the Korean GEO-environmental Society
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• v.9 no.4
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• pp.63-76
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• 2008

This research was carried in order to improve design technique for the vertical shaft of which design guide has not been proposed clearly. The deformation tendency of vertical shaft and distribution of the earth pressure around shaft were reviewed with both of theoretical earth pressure distribution suggested in design criteria and measured data which had been gained from 2 constructing shaft. The distribution of earth pressure applied on the vertical shaft was similar with the result of previous theory for the earth pressure proposed by Shin (2007). Moreover it was observed that asymmetric deformation and earth pressure around vertical shaft were caused by inhomogeneity and anisotropy of the ground. The asymmetric earth pressure ratio ($R_p$) in soil and weathered rock were divergent according to the shape ratio. In addition, it is more reasonable that the value of asymmetric earth pressure ratio ($R_p$) is considered less than 0.35 in the case of constructing shaft under rock.

• Journal of the Korean Institute of Rural Architecture
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• v.17 no.2
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• pp.51-58
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• 2015

10 years ago, in Sijeon-ri, Dogo-myeon, Asan-si, the existing stream was repaired to develope Mt. Dogo trail and irrigation systems through road expansion pavement construction and small stream repair construction. The trees such as persimmon and willow are eliminated that rowed on both sides of the stream and dredging work to dig the rock and sand have been performed. As a result, wide asphalt road was built, also flood damage worries were reduced. 10 years passed and now, how did local residents think about the stream repaired before and after? Village residents, public officials, and the stream construction engineer were interviewed. Villagers indicated a problems that brook became a place where water peppers were taking over and water was stagnating due to the slow velocity so nothing could live and natural landscape like a wash place and the cascade disappeared, because rock and sand were taken out brought soil into the brook. Public officials and engineers were aware of the problems at the time of the stream. Now that construction is completed after 10 years, Both realistically and budgetary to restoration would be difficult. However, it is necessary to seek for waterfront space which can be restored or replaced by a part of the stream like similarly before. In addition, it is necessary to restore to the progression of a natural stream which connect with stairs(or slope) - small waterfalls - pools - wash place. In this paper, we hope to take a lesson from the Sijeon-ri model and make rural stream construction be prepared with consideration about not only distinct characteristics of specific area but also the opinion of local resident.

• Journal of Forest and Environmental Science
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• v.37 no.3
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• pp.206-216
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• 2021

Deutzia paniculata Nakai, a rare and endemic plant, has limited distribution throughout the North and South Gyeongsang provinces of South Korea. The D. paniculata community grows mostly on the stony slopes of forests, valley edges, and rock layers at 250-960 m in altitude, where deciduous trees are dominant and high humidity is maintained. Correlation analysis of vegetation and environmental factors found that the Walter's dogwood-mulberry community was correlated with soil acidity (pH). Whilst the queritron community had correlations with distance from the valley, rock rate and slope. The natural habitat of the Palgongsan Mountain in Daegu is known to have high genetic diversity, had eight D. paniculata individuals recorded from 2014 to 2018, and 12 individuals recorded in 2020 (new individuals due to a newly created space within the herbaceous layer caused by grass mowing works), it is therefore unlikely that the community would perish unless there was an artificial disturbance. To conserve the natural habitats of D. paniculata, oppression by Sasa borealis, damage, increase in crown density of the upper layer, overexploitation, and absence of seedlings should be carefully investigated. In addition, response measures should also be established and the impact on seed fullness and the reproductive characteristics of D. paniculata recorded. To restore declined genetic diversity, individuals from high genetic diversity regions, such as Palgongsan Mountain, should be artificially transplanted.

• Journal of Environmental Analysis, Health and Toxicology
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• v.21 no.4
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• pp.237-242
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• 2018

Strontium (Sr) commonly exists in rock, groundwater, soil, plants, and animals. The Sr isotope ratio offers important information as a tracer on nature because the Sr isotopic composition is not fractionated by any biological process in these ecosystems. Hence, Sr isotope ratio has been used in several studies on tracing the Sr source for contaminated sites and human migration. In this study, we developed a separation method for Sr content, and then improved Sr isotope analysis using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). A powdered rock standard (NIST 2710a) was used to determine the removal of interference elements (Rb and Ca) and the recovery rate of Sr content. The results ranged from 98% to 106%. Additionally, three standard samples (NBS 987, IAPSO and NIST 1486) were analyzed to evaluate the precision and accuracy of the results. The measured $^{87}Sr/^{86}Sr$ ratio for all the samples were consistent with the reported values, within an error. These results indicate that our established Sr separation and Sr isotope measurement methods are reliable and can hence be useful in the fields of environmental and forensic sciences.

• Journal of the Korean Geotechnical Society
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• v.38 no.9
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• pp.45-52
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• 2022

Because discontinuity in the rock mass and contact of soil-structure interaction exhibits coupled thermal-hydromechanical (THM) behavior, it is necessary to develop an interface element based on the full governing equations. In this study, we derive force equilibrium, fluid continuity, and energy equilibrium equations for the interface element. Additionally, we present a stiffness matrix of the elastoplastic mechanical model for the interface element. The developed interface element uses six nodes for displacement and four nodes for water pressure and temperature in a two-dimensional analysis. The fully coupled THM analysis for fluid injection into a fault can model the complicated evolution of injection pressure due to decreasing effective stress in the fault and thermal contraction of the surrounding rock mass. However, the result of hydromechanical analysis ignoring thermal phenomena overestimates hydromechanical variables.

• Geomechanics and Engineering
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• v.31 no.6
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• pp.573-582
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• 2022

The geometry of the gravity-type anchorage changes depends on various factors such as the installation location, ground type, and relationship with the upper structure. In particular, the anchorage geometry embedded in the ground is an important design factor because it affects the pull-out resistance of the anchorage. This study examined the effect of four parameters, related to anchorage geometry and embedded ground conditions, on the pull-out resistance in the gravity-type anchorage through two-dimensional finite element analysis, and presented a guide for major design variables. The four parameters include the 1) flight length of the stepped anchorage (m), 2) flight height of the stepped anchorage (n), 3) the anchorage heel height (b), and 4) the thickness of the soil (e). It was found that as the values of m increased and the values of n decreased, the pull-out resistance of the gravity-type anchorage increased. This trend is related to the size of the contact surface between the anchorage and the rock, and it was confirmed that the value of n, which has the largest change rate of the contact surface between the anchorage and the rock, has the greatest effect on the pull-out resistance of the anchorage. Additionally, the most effective design was achieved when the ratio of the step to the bottom of the anchorage (m) was greater than 0.7, and m was found to be an important factor in the pull-out resistance behavior of the anchorage.

• Korean Journal of Soil Science and Fertilizer
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• v.1 no.1
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• pp.27-41
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• 1968

In order to clarify the effect of various forms or phosphate on the production of paddy in Korea and to find out the superiority of any form, a number of field and pot experiments involving various phosphate fertilizers were carried out in addition to conducting one each of sand culture and soil culture pot experiments in 1963 and 1964. The results of these studies are summarized as follows: 1. In sand culture experiment, the best effect of a phosphate fertilizer was obtained with the mono-calcium phosphate which is soluble in water, followed by citric acid soluble phosphate such as fused phosphate and di-calicum phosphate. However, in the pot culture and field experiments, fused phosphate had shown it's superiority than triple superphosphate which contains water soluble form of phosphate followed by hypo phosphate, roasted phosphate, compound fertilizer, and slag phosphate. The effect of rock phosphate was the least in most cases. 2. The superiority of fused phosphate to triple super phosphate in soil culture was supposed to be: a) The fused phosphate can neutralize the soil acidity. b) The fused phosphate can supply magnesium and magnesium lead to the balanced conditions of exchangeable bases in soils. c) The magnesium in the fused phosphate helps the transportation of phosphate, and regulate the absorption of the element.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.453-467
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• 2018

The excavation performance and the cutting tool wear prediction of shield TBM are very important issues for design and construction in TBM tunneling. For hard-rock TBMs, CSM and NTNU model have been widely used for prediction of disc cutter wear and penetration rate. But in case of soft-ground TBMs, the wear evaluation and the excavation performance have not been studied in details due to the complexity of the ground behavior and therefore few testing methods have been proposed. In this study, a new soil abrasion and penetration tester (SAPT) that simulates EPB TBM excavation process is introduced which overcomes the drawbacks of the previously developed soil abrasivity testers. Parametric tests for penetration rate, foam mixing ratio, foam concentration were conducted to evaluate influential parameters affecting TBM excavation and also ripper wear was measured in laboratory. The results of artificial soil specimen composed of 70% illite and 30% silica sand showed TBM additives such as foam play a key role in terms of excavation and tool wear.

• The Journal of the Petrological Society of Korea
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• v.19 no.3
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• pp.181-197
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• 2010

This study is for finding a geoscientific factor for clarifying the source soil of the ancient earthenware finding. The used samples were the earthenware, soil and rocks, which were collected at the Gyeongju, Gyeongsan and Haman area. The chemical and mineralogical study for the samples were carried out for understanding the change of mineralogical and chemical composition among them. The mineralogical compositions of the earthenware are different from those of the soils from the surrounding area, which suggests that the mineralogical approach for clarifying the source soil of the earthenware should be difficult. Major element compositions of the earthenware also are different from those of the surrounding soils, which suggests that the comparison of the chemical composition using the major elements might be difficult for deducing the source soil of the earthenware. However, PAAS-normalized rare earth element (REE) patterns and Nd model ages among the rock, soils and earthenware from the same sampling sites show similar characteristics one another compared to those of the major element compositions. Nd-Sr isotopic systematics among the earthenware, soils and rocks also show a close relationship. Our results suggest that REE and Nd-Sr isotope geochemistry might be more useful than the other geochemical technique in clarifying the source soils of the ancient earthenware.

• Journal of agriculture & life science
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• v.43 no.2
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• pp.1-8
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• 2009

The limestone area covers the narrow range of the Korean Peninsula, and it consists of a peculiar ecosystem and topography. Therefore, this study on limestone area was carried out classification of vegetation type, physicochemical properties of forest soils and correlation between environment factors and vegetation types in order to furnish fundamental data for the forest management of limestone area. Forest vegetation was classified into two community groups such as Quercus variabilis community group and Quercus mongolica community group, and it was classified into eight vegetation units. Soil texture of survey sites showed largely silt loam and soil pH indicated the value of mean 7.55 in the A layer of soil profile. Content of exchangeable cation such as calcium ion ($Ca^{2+}$) and magnesium ion ($Mg^{2+}$) showed $26.04cmol_{c}/kg$ and $2.93cmol_{c}/kg$, respectively, which was about ten times higher than average of other regions of Korea. According to corelation between environmental factors and vegetation units, Q. variabilis community group was positively correlated to soil pH, slope degree and the rate of bare rock, and content of calcium ion ($Ca^{2+}$), and then Q. mongolica community group was positively correlated to altitude, respectively.