• Journal of Soil and Groundwater Environment
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• v.12 no.6
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• pp.29-37
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• 2007

Shallow alluvial groundwaters in Korea of tell exceed the Korean Drinking Water Standard for dissolved iron (0.3 mg/L), which is one of the important water quality problems, especially in the use of bank infiltration technique. Using the reactive transport modeling, in this study we simulated the effectiveness of injection-and-pumping technique to remove dissolved iron in groundwater. The results of simulation showed that pumping of groundwater after injection of oxygenated water into aquifers is very effective to acquire the permissible water quality level. Groundwater withdrawal up to several times of irjected water in volume can be applicable to yield drinkable water. Potential problems such as clogging and permeability lowering due to in-situ precipitation of iron hydroxides may be insignificant. We also discuss on the mechanism and spatial extent of iron removal in aquifer.

• Korean Journal of Soil Science and Fertilizer
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• v.22 no.4
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• pp.271-279
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• 1989

Mean values representing the particle size distribution and some chemical properties for the cultivated soils were obtained from the analysis results of the typical profiles, which were described by the detailed soil maps throughout Korea. Analysis results of 5,215 soil samples (3,075 for paddy and 2,140 for upland) were available for the determination of mean values. The results are under. 1. Paddy topsoil contained 20.4% for clay, 5.8 for pH, 2.6% for organic matter, 10.4me/100g for exchangeable K, and 89ppm for available $P_2O_5$. Upland topsoil did 17.3% for clay, 5.5 for pH, 1.8% for organic matter, 9.lme/100g for CEC, 0.29me/100g for exchangeable K, and 103ppm for availabal $P_2O_5$. 2. Soil properies for paddy were markedly influenced by the reliefs. Topsoil contained 21.4% for clay, 6.0 for pH, 2.2% for organic matter, 10.8me/100g for CEC, 0.39me/100g for exchang-cable K and 57ppm for available $P_2O_5$ on the fluvio-marine plain, 15.3%, 5.7, 2.0%, 8.6me/100g, 0.17me/100g and 76ppm on the alluvial plain, 18.8%, 5.9, 2.7%, 10.4me/100g, 0.19me/100g and 80ppm on the valleys and fans, 25.0%, 5.7, 2.5%, 11.5me/100g, 0.26me/100g, 0.27me/100g and 141ppm on the moutain foot slopes, respectively. 3. Soil Properties for upland, also, were markedly influenced by the reliefs. Topsoil contained 5.5% for clay, 5.7 for pH, 1.1% for organic matter, 4.7me/100g for CEC, 0.17me/100g for exchangeable K and 50ppm for available $P_2O_5$ on the fluvio-marine plain, 10.3%, 5.5, 1.4%, 7.6me/100g, 0.26me/100g and 160ppm on the alluvial plain, 13.9%, 5.4, 1.8%, 9.3me/100g, 0.24me/100g and and 184ppm on the valleys and fans, 29.8%, 5.3, 2.1%, 11.2me/100g 0.40me/100g and 58ppm on the alluvial plain, 20.0%, 5.7, 2.7%, 11.4me/100g, 0.32me/100g and 116ppm on the mountain foot slopes, and 24.6%, 5.3, 1.8%, 10.2me/100g, 0.28me/100g and 51ppm on the rolling and Hill. 4. All chemical properties did not reach the ideal value for maximizing land capability. 5. Organic matter, exchangeable cations and available $P_2O_5$ were not normally distributed. Intervals of one and two standard deviations about mean of an approximately normal distribution were calculated.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1203-1210
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• 2011

Function-driven metagenomic analysis is a powerful approach to screening for novel biocatalysts. In this study, we investigated lipolytic enzymes selected from an alluvial soil metagenomic library, and identified two novel esterases, EstDL26 and EstDL136. EstDL26 and EstDL136 reactivated chloramphenicol from its acetyl derivates by counteracting the chloramphenicol acetyltransferase (CAT) activity in Escherichia coli. These two enzymes showed only 27% identity in amino acid sequence to each other; however both preferentially hydrolyzed short-chain p-nitrophenyl esters (${\leq}C_5$) and showed mesophilic properties. In vitro, EstDL136 catalyzed the deacetylation of 1- and 3-acetyl and 1,3-diacetyl derivates; in contrast, EstDL26 was not capable of the deacetylation at $C_1$, indicating a potential regioselectivity. EstDL26 and EstDL136 were similar to microbial hormone-sensitive lipase (HSL), and since chloramphenicol acetate esterase (CAE) activity was detected from two other soil esterases in the HSL family, this suggests a distribution of CAE among the soil microorganisms. The isolation and characterization of EstDL26 and EstDL136 in this study may be helpful in understanding the diversity of CAE enzymes and their potential role in releasing active chloramphenicol in the producing bacteria.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.293-307
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• 2012

Shear wave velocity is commonly invoked in explaining geophysical phenomena and in solving geotechnical engineering problems. In particular, the importance of shear wave velocity in geotechnical earthquake engineering has been widely recognized for seismic design and seismic performance evaluation. In the present study, various insitu seismic tests were performed to evaluate geotechnical dynamic characteristics at 183 sites in Korea, and shear wave velocity profiles with depth were determined to be representative of the dynamic properties at the investigated sites. Subsurface soil and rock layers at the target sites were reclassified into five geotechnical layers: fill, alluvial soil, weathered soil, weathered rock, and bedrock, taking into account their general uses in geotechnical earthquake engineering practice. Average shear wave velocity profiles for the five geotechnical layers were obtained by synthesizing the shear wave velocity profiles from seismic tests in the field. Based on the profiles, a representative shear wave velocity value was determined for each layer, for use in engineering seismology and geotechnical earthquake engineering.

• Magazine of the Korean Society of Agricultural Engineers
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• v.33 no.2
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• pp.112-119
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• 1991

Some experiments were carried out to investigate the effects of freezing and thawing on the strength and strain characteristics of alluvial silty clay under the different temperatures, loading and moisture conditions. The results were as follows; 1. The soil used was proved to be consisted of silty clay with honey-combed structure, and showed higher dilatancy, frost activity and lower stability in natural state. 2. Soil treated with freezing and thawing cycles showed lower compressive strength compared with the non treated, The strength decreased with incement of freezing and thawing cycles. It's shapes of stress-strain curves were flat and did not formulate a peak while the peak strength of higher moisture content soil decreased with the increment of moisture content. It's decrement ratio was most distinctly shown at the first one cycle of freezing and thawing. 3. The cohesion decreased due to freezing and thawing cycles but internal frcition angle was not changed. 4. The liquid limit decreased with increment of freezing and thawing cycles, and became almost constant after three cycles of freezing and thawing. 5. The strength under simple loading at failure mode was appeared to be higher compared with the cyclic loading after freezing and thawing but initial moisture content effect was not observed. 6. Ice lense was not observed within 50% of ice content ratio but observed over 100%. The higher the ice content ratio, the higher the peak strength. As a matter of fact, it seems that an optimum ice content ratio exists for plastic mode and the least compressive strength.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1039-1048
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• 2018

In urban tunnel construction, most of the Shield TBM method is applied to secure the safety of buildings and to minimize risks. On the other hand, in the urban development process, landfills are often embanked or improving in many cases, so that the boundary between the surface and the rock is often heterogeneous. In case of ground condition such as alluvial soil, granite, decomposed granite, core stone and rock with various layers, datas on shield TBM advancing according to each ground condition are analyzed, The characteristics of machine load were compared and analyzed. As a result, it can be predicted that the change of ground condition can be predicted by the tendency of discharge volume, thrust force and cutting wheel torque when the cutter is checked and replaced regularly on advancing under maintaining the design slurry pressure.

• Korean Journal of Soil Science and Fertilizer
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• v.25 no.3
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• pp.195-201
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• 1992

A Potential acid sulfate soil derived from continental Holocene deposits on the fan-base was found and it was characterized with improvement practices. Artesian wells were scattered in the area, and the imperfectly drained soils were featured by having fine loamy with 7~30% of gravels. The potential acid sulfate soil layers were typified by having darkness in color with around 3.3~3.8% of O.M. and 0.34~0.41% of total sulfur. Soil pH ranged from 3.4 to 3.8 but it was decreased to 1.9~2.5 after oxidation with $H_2O_2$. Ground water sprang out from an artesian well contained a high amount of minerals such as Na, Ca, Mg, K, etc. and about 80ppm of sulfate which seemed to be responsible for pyrite formation. The soil was classified to member of "Fine loamy, mixed, acid, mesic, sulfic Haplaquepts" in taxonomically, and "weak potential acid sulfate soils" in interpretatively. The installation of tile drains with adding fine earth and liming were effective. However, the pH goes down to 4.8 again after 3 years of improvement practices.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.81-85
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• 1996

Tentative consolidation criteria, a kind of land suitability classification, was established for cultivated upland soils. The criteria were composed of systematically quantified individual soil properties such as physiography(relief), slope, available soil depth etc., and local features such as soil complexity, mapping unit separation, width/length ratio etc. The criteria was applied to upland soils in granite area, and sedimentary rock area. It was clear that the comparison of local features among candidated areas, and classification of suitability classes for land consolidation of upland soils was satisfactory for selection. The status of the areas classified to "Well suitable" were distributed on alluvial plains or less dissected rollings with lower complexity of soils occurred and extended acreage in each mapping unit. On the other hand, the areas classified as "Unsuitable" were distributed on the elongated narrow valleys with quite divided mapping units by paddy fields on the valley bottom.

• Korean Journal of Soil Science and Fertilizer
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• v.20 no.1
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• pp.1-6
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• 1987

This study was designed to evaluate the characteristics, land use and genesis of well adapted paddy soils. They were mostly classified as the Haplaquepts in the U.S.D.A soil taxonomy and as the Grey soils in the Japanese soil classification system. The proportion of these soils in the total acreage of paddy lands was thirty three percents. The fifty four percents in average of these soils were distributed on the local valley and fans on gentle slopes developed from granite, granite gneiss and shale parent materials. The rests were on the fluvio-marine deposits and alluvial deposits. The soils were characterized with prominant development of gleized horizons and clayey or fine loamy textured category. The available soil depth and the ground water level were relatively deep. The base saturation percent were high with weak acidic pH. The potential productivity of these soils was high.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.3
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• pp.270-274
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• 1996

To estimate the suitable method of phosphorus application in puddled-soil drill seeding of rice, available phosphorus, appearance of algal water bloom, and rice yield were investigated in paddy soil of Honam area from 1994 to 1995. Available phosphorus content with different regions was the highest in the east-west inland region of Noryeong mountain range and the inland region of Honam area and it was the lowest in the Charyeong south plains region. Available phosphorus content was the highest in the alluvial plains. and it was the lowest in dilluvial terrace. Frations of phosphorus in Jeonbug series were high in the order of Ca-P, Fe-P, and Al-P, respectively. Algal water bloom occurred highly in 100% and 70% basal applications before seeding, and slightly in no-fertilizer and 100% application of 3-leaf stage in puddled-soil drill seeding of rice. Suitable amount of phosphorus application was 21kg/ha in the single cropping paddy field of Fluvio-marine plain, and rice yield was increased 6% at 50% basal application.