• Korean Journal of Environment and Ecology
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• v.38 no.2
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• pp.156-168
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• 2024

This study was carried out to provide fundamental data for forest land and the environment by investigating the vegetation structure and soil properties of forest land where Sarcodon impricatus are present. The study area was divided into the Quercus mongolica community, dominated by Q. mongolica and the Quercus variabilis community, a mixed forest with Q. variabilis, Q. mongolica and Pinus densiflora. Also, Calamagrostis arundinacea in the former community and Disporum smilacinum and Carex siderosticta in the latter community showed significant levels as indicator species. Both communities showed a strong correlation between available phosphate and pH, sand, and clay, and the high organic matter content and slightly acidic pH of the soil are believed to be related to the development of S. impricatus. The species appearing at the lower layer continue to dominate because the species appearing at the upper layer have secured realized niches. The site was distributed in a relatively humid place in a north-east direction, and soil was developed with a thin litter layer and low rock exposure. In the selected S. impricatus growing areas, vegetation centered on highly adaptable species to disturbance or external interference was developed. Therefore, it is expected to be used as fundamental data to promote the occurrence of S. impricatus during artificial cultivation, as it is possible to identify the stand where S. impricatus occurs indirectly.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.25 no.2
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• pp.76-93
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• 2013

The hydrodynamics in the Youngsan River Estuary has changed due to coastal developments such as the estuary dam and two tidal barriers. As the freshwater discharge is artificially controlled, the circulation pattern is different from those of natural estuaries and the river-born sediment supply is restricted. 3D numerical modeling system EFDC was applied to investigate the sediment transport pattern and budget in summer with river floods. The real-time driving forces and the fluvial sediment discharges from the watershed modeling were assigned for the simulation period. The size classes of sand, silt and clay were adopted based on the grain-size distribution of bottom sediments. The modeling results were calibrated and validated with the observed tides, tidal currents and suspended sediment concentrations. The suspended sediments are transported to the offshore at surface layer, whereas upstream toward the dam at mid- and bottom layers in August 2011. The characteristic estuarine circulation induced by the freshwater discharge from the dam, causes the deposition of silt-sized sediments on the whole and the sustained suspension of clay-sized sediments.

• The Journal of Engineering Geology
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• v.21 no.3
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• pp.213-219
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• 2011

Transient/time-domain electromagnetic (TEM) soundings were carried out on reclaimed land, since the TEM sounding has good resolution of a conductive and thin overburden. The reclamation material is marine clay dredged from the seafloor, which is currently undergoing consolidation in the upper part of the dredged layer. The conductivity of the marine-origin clay is generally more than 0.3 S/m. The aim of the TEM sounding was to determine the depths of weathered and soft rocks overlain by thick and conductive overburden. The TEM responses were measured at delay times of 0.050-20.575 ms with a $30{\times}30$ m coincident loop array. Data from the TEM inversion and core logging indicate that the resistivities of the conductive overburden are less than 2 ${\Omega}$-m, while those of the weathered and soft rocks are 10-20 and 70 ${\Omega}$-m, respectively. The depth to weathered rock is 26-58 m and the depth to soft rock is 46-75 m.

• Applied Biological Chemistry
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• v.30 no.4
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• pp.351-356
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• 1987

This study was conducted to investigate the absorption and translocation of pretilachlor [2-chloro-2, 6-diethyl-N-(n-propoxyethyl)-acetanilide] in plants and to evaluate the mobility in soil using the $^{14}C-or$ non-labelled compound in laboratory. Rice plant(Oryza sativa L.) was very tolerant to pretilachlor. Echinochloa crus-galli P. Beauv. was completely controlled by pretilachlor at 60g a.i./10a. At the 120g a.i./l0a, growth of Cyperus serotinus Rottb. and Sagittaria pygmaea Miq. was inhibited by 75% and 25%, respectively. The growth inhibition depended on absorbed amount of $^{14}C-pretilachlor$. The greatest concentration of $^{14}C$ was found in E. crus-galli, whereas the lowest was determined in rice plant. The rate of absorption and translocation in E. curs-galli was faster than in rice plan. Pretilachlor moved to 6cm deep in sandy clay loam, clay loam and loam soils, but to 10cm in sandy loam soil. In the soils herbicide-treated layer was found 0 to 2cm profile.

• The Journal of Engineering Geology
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• v.17 no.1 s.50
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• pp.125-133
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• 2007

The environmental and geotechnical properties are investigated to the 8th landfill area made of only sewage sludge in Nanji-Do. To do this, the soils are sampled in this area, and leaching tests, heavy metal content tests, and so on are performed to research the environmental properties. As the result of heavy metal content tests, Pb, Zn, Cu, Ni, Cd and Cr were leached from the sewage sludge. Because the leaching concentration of Cu is more than the standard value of California state, Cu content have to bring down during the recycling of the sewage sludge. Meanwhile, a series of tests concerning specific gravity, liquid and plastic limits, compaction, permeability and shear strength is performed to research the geotechnical properties. The sewage sludge is consisted of sand, silt and clay, and is classified into non-organic silt or organic clay with 42.3% of plastic index. As the result of compaction test, it is expected that the compaction effect according to variation of water contents is low relatively because the dry unit weight is low and the curve of compaction forms flatness. Also, as the result of direct shear tests, the cohesion is $0.058kg/cm^2$, and the internal friction angle is $14^{\circ}$. Taking everything into consideration, the various problems are happening in case of recycling the sludge like the cover layer of landfill and so on because the compaction is bad, and the shear strength is low. Also, it is expected that the ground water pollution caused by leaching the heavy metal into the sludge. To do recycling the sewage sludge in this site, supplementary and treatment programs should be prepared.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.1
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• pp.54-59
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• 2009

It was difficult for the existing rotary kiln to fabricate the fine aggregates under 3 mm due to the sticking phenomenon between specimens. In this study, the vertical type fluidizing furnace was designed and manufactured by which the lightweight fine aggregates of specific gravity $1.1{\sim}1.7$, water absorption $11{\sim}19%$ could be fabricated from the green body of clay: stone sludge: spent bleaching clay = 60 : 30 : 10 (wt%) without sticking-together happening. The minimum sintering temperature for bloating of aggregates was $1130^{\circ}C$. The specimens sintered over $1140^{\circ}C$ showed the typical bloating characteristics of lightweight aggregates and an inner layer was discovered due to widened cracks on a surface. But the crack on a surface did not propagate into a black core area so had no effect on a water absorption of aggregates. The sintering temperature made the thickness of shell and the black core area thin and expanded respectively but the sintering time did not affect the microsturcture of aggregates. The water absorption of aggregates decreased with increasing temperature owing to increased amount of liquid formed on a surface. Also sintering time affected a lot on a water absorption because it takes a time to form a liquid, which change the open pores to closed pores by blocking.

• Journal of the Korean earth science society
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• v.32 no.6
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• pp.537-547
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• 2011

Electrical resistivity tomography surveys using boreholes were applied to reveal the cause of a catastrophic land subsidence accompanied by the excessive groundwater withdrawal in urban karst area and to map the connectivity of disseminated cavities over the study area. In order to understand the hydrogeological characteristics, resistivity using exsitu core samples, groundwater level for five boreholes, and hydraulic conductivity using slug test were measured. The hydraulic conductivity variation ranging from 0.8 to $9.3{\times}10^{-4}\;cm/s$ for five boreholes and a gentle slope of groundwater level indicated that there is no significant characteristics of hydraulic heterogeneity. Core samples of the lime-silicated rock were classified as three groups including cracked, weathered, and fresh and measured the resistivity values ranged from 103 to 161, 218 to 277, and 597 to 662 ohm-m, respectively. Drilling results that showed the cavity filled with clay materials and tomogram for this region indicated resistivity value lower than 50 ohm-m. From the inverted resistivity results for each section with five boreholes, cavity and fractured layer were distributed along the depth between 10 and 20 m overall area and cavities ranging from 4 to 6 m filled with clay materials.

• International Journal of Highway Engineering
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• v.16 no.6
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• pp.105-113
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• 2014

PURPOSES: The objective of this paper is to select the confidential intervals by utilizing the second moment reliability index(Hasofer and Lind; 1974) related to the number of load applications to failure which explains the fatigue failure and rut depth that it indicates the permanent deformation. By using Finite Element Method (FEM) Program, we can easily confirm the rut depth and number of load repetitions without Pavement Design Procedures for generally designing pavement depths. METHODS : In this study, the predictive models for the rut depth and the number of load repetitions to fatigue failure were used for determining the second moment reliability index (${\beta}$). From the case study results using KICTPAVE, the results of the rut depth and the number of load repetitions to fatigue failure were deducted by calculating the empirical predictive equations. Also, the confidential intervals for rut depth and number of load repetitions were selected from the results of the predictive models. To determine the second moment reliability index, the spreadsheet method using Excel's Solver was used. RESULTS : From the case studies about pavement conditions, the results of stress, displacement and strain were different with depth conditions of layers and layer properties. In the clay soil conditions, the values of strain and stresses in the directly loaded sections are relatively greater than other conditions. It indicates that the second moment reliability index is small and confidential intervals for rut depth and the number of load applications are narrow when we apply the clay soil conditions comparing to the applications of other soil conditions. CONCLUSIONS : According to the results of the second moment reliability index and the confidential intervals, the minimum and maximum values of reliability index indicate approximately 1.79 at Case 9 and 2.19 at Case 22. The broadest widths of confidential intervals for rut depth and the number of load repetitions are respectively occurred in Case 9 and Case 7.

• Korean Journal of Soil Science and Fertilizer
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• v.12 no.1
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• pp.25-34
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• 1979

To clealify the cause of barley and wheat sterility that occurred 77 / 78 cultivation period in Yeongnam area, a few environmental conditions were analyzed. The results are summarized as follows; 1. During the important growing stages such as meiosis and heading stages of barley encountered with severe droughtiness and unusual low temperature. 2. Soil moisture contents in the double cropping paddy soils were higher than cultivated uplands, and in the subsoils than the surface soils, in the clay soils than the sandy soils, in the northern aspect than the southern aspect of slope, respectively. 3. The sterilizing percentage of barley in the double cropping paddy fields were lower than cultivated uplands, in the alluvial fans and plains were lower than cultivated uplands, in the alluvial fans and plains were lower than in rolling or in foot slopes and the northerm aspect of slopes were lower than southern aspect. 4. The sterilizing percentage in the sandy soils were higher than clay soils and in the soils that have shallower plowing layer and shallower available depth had higher sterility. 5. The sterilizing percentage of barley had negative correlation with soil moisture contents in the surface and subsoils in both of cultivated upland or double cropping paddy fields. 6. The droughtiness that prevailed over reproductive growing stages of barley might be cause the sterility and the severe coldness also could be accelerate the phenomenon.

• Journal of the Mineralogical Society of Korea
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• v.24 no.3
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• pp.165-178
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• 2011

The potential of petroleum generation was investigated by clay mineralogical changes of illite-smectite on the sedimentary basins: Tertiary Pohang basin and Cretaceouls Gyeongsang basin on land, and offshore basins east and west of Korea. Only disordered illite-smectite mixed layer minerals occur in the Pohang sediment, where petroleum generation cannot be expected due to low temperatures below $100^{\circ}C$. By contrast, the Gyeongsang basin is characterized by the occurrence of illite and high temperatures above $200^{\circ}C$ which are obtained by illite crystallinity. The high temperatures indicate that the Gyeongsang sediment ha, already passed through the oil generation stage. The change of disordered illite-smectite to R-l ordered illite-smectite is shown in the sediment of the East Sea continental shelf area at a depth of 2,500 m. Therefore, the oil generation can be expected in the sediments below the depth of 2,500 m. The sequential change of disordered illite-smectie to R=3 ordered illite-smectite through R=l ordered illite-smectite occurs in the sediments of West Sea continental shelf area with burial depth which shows the favorable condition for oil and gas generation. The temperatures of sediments measured by illite-smectite indicate that hydrocarbon potential is very low in the onland basins but high in the continental shelf areas.