• Korean Journal of Soil Science and Fertilizer
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• v.44 no.5
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• pp.727-733
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• 2011

A new Korean standard for the determination of Cr(VI) in soils has been officially published as ES 07408.1 in 2009. This analytical method is based on the hot alkaline digestion and colorimetric detection prescribed by U.S. EPA method 3060A and 7196A. The hot alkaline digestion accomplished using 0.28 M $Na_2CO_3$ and 0.5 M NaOH solution (pH 13.4) at $90{\sim}95^{\circ}C$ determines total Cr(VI) in soils extracting all forms of Cr(VI), including water-soluble, adsorbed, precipitated, and mineral-bound chromates. This aggressive alkaline digestion, however, proved to be problematic for certain soils which contain large amounts of soluble humic substances or active manganese oxides. Cr(III) could be oxidized to Cr(VI) by manganese oxides during the strong alkaline extraction, resulting in overestimation (positive error) of Cr(VI). In contrast, Cr(VI) reduction by dissolved humic matter or Fe(II) could occur during the neutralization and acidic colorimetric detection procedure, resulting in underestimation (negative error) of Cr(VI). Futhermore, dissolved humic matter hampered the colorimetric detection of Cr(VI) using UV/Vis spectrophotometer due to the strong coloration of the filtrate, resulting in overestimation (positive error) of Cr(VI). Without understanding the mechanisms of Cr(VI) and Cr(III) transformation during the analysis it could be difficult to operate the experiment in laboratory and to evaluate the Cr(VI) results. For this reason, in this paper we described the theoretical principles and limitations of Cr(VI) analysis and provided useful guidelines for laboratory work and Cr(VI) data analysis.

• Journal of Soil and Groundwater Environment
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• v.17 no.1
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• pp.42-46
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• 2012

The ISO document of ISO/TC/190/SC3/WG11/N11 is a working draft of international standard (WD) dealing with analytical method for the determination of explosives and related compounds using high performance liquid chromatography. The scope of this WD covers the storage of samples, preparing test portion, extraction and instrumentation. The main purpose of this study was to improve the extraction conditions which were already adopted in the WD. For this purpose, mechanical shaking method could be corresponded up to 18 hours of ultrasonic bath extraction in the WD was tested. Methanol was also tested with the intention of being added as an extracting solvent other than acetonitrile in the WD. According to the results, 16 hours of mechanical shaking method showed statistically the same effectiveness as that of 18 hours of ultrasonic bath extraction. In case of extracting solvent, methanol also showed statistically the same extraction capability as acetonitrile for DNB, TNT, 2-A-DNT and 2,4-DNT. However, the recovery rate of TNB with methanol extraction was 40% higher than that of acetonitrile extraction. Through adding mechanical shaking method into committee draft (cf. the next stage draft of the WD during the process for making international standard), ISO standard of analyzing explosives and related compounds in soil would become more useful in dealing with huge number of field samples in the laboratory. In other aspect, adopting methanol as an alternative extracting solvent would be very effective in the terms of exchangeability with GC-ECD/MS method which is being developed by German experts.

• Journal of Soil and Groundwater Environment
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• v.23 no.5
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• pp.17-25
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• 2018

The Boroo area in Mongolia is known to have been contaminated with heavy metals due to irregular gold mining activities and the release of mercury from gold extraction process. Soil and mine tailings were collected to analyze contamination patterns of heavy metals in the Boroo area. Analyses revealed that mercury, arsenic and cadmium concentrations exceeded the regulatory standard of the nation (Mongolia National Standard). In case of mercury, about 80% of the survey area was over the limit and the concentration distribution heavily influenced by influx of mercury through water transport. Soil contamination by arsenic was most severe that the concentration exceeded the regulatory limit in almost entire survey area, showing peak concentrations at nearby streams and river along with ore processing facilities. For cadmium, about 20% of the survey area was over the limit with the concentration distribution similar to that of arsenic.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.2
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• pp.3778-3783
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• 1975

The objective of this study is to determine an appropriate cement of soil-cement in which silty soil of salty tidal flat with low plasticity was used. Physical, chemical and mechanical tests were conducted to find out the standard properties of the soil to be used. Various cement contents used in this test were 8%, 10%, 12%, and 14%, and the compressive strength was tested after 7 days and 28 days of standard curing in the above each cement content respectively. The results obtaind are summarized as follows. 1. As the cement content was increased from 8% to 14%, Maximum dry density (M.D.D.) and optimum moisture content (O.M.C.) were not changed remarkably. 2. Density of soil-cement was directly proportional to cement content and inversely proportional to water content. 3. OMC was generally decreased in proportion to the increase of cement content. 4. Compressive stranth was directly proportional to centent and inversely proportional to water content. 5. In freezing and thawing test, maximum loss of 10% in the total Weight was found on the 8% cement mixture. and This loss was rapidly decreased to 2% when the Cement content of the mixture was more than 10%.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.121-128
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• 2014

Development of the economic methods and the design of the standard sections needs the more project fund and land than ever leads to the objection of enlarging canal arrangement to need economic construction method development and standard design for supporting it. The objective of this study was to evaluate the performance of selected sediment reduction methods to reduce sediment discharges from drain and irrigation of different land types (Mountain, Flatten, Reclaimed land). This study was carried out to analysis for the soil loss and sediment of drain and irrigation by comparing RUSLE method and amount of sediment from amount of dredging data of Korea Rural Corporation. The results of study were analyzed and summarized as follow. Size of soil sediment from the upper region of drain and irrigation of mountains bigger than lower region. But in case of flatten and reclaimed land, size of soil sediment from the upper and lower region of drain and irrigation did not classified. In case of comparison drain and irrigation without classifying of land type, size of soil sediment from irrigation is bigger than drain.

• Journal of Biosystems Engineering
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• v.28 no.4
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• pp.369-376
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• 2003

This study was conducted to develop a precision measurement method of water content in soil (find sand and silty sand) using dual RF impedance changes. The electrically stable perpendicular plate capacitive sensor was fabricated and utilized to sense the water content in soil. Crystal oscillators of 5 and 20 MHz and related circuits were designed to detect the capacitance changes of a perpendicular plate capacitive sensor with soil samples at various volumetric water contents. A multiple regression model for volumetric water content having dual oscillation frequency changes at 5 and 20 MHz as independent variables resulted in coefficient of determination of 0.963 and standard error calibration of 0.030 cm$^3$/cm$^3$ for calibration and coefficient of determination of 0.966, standard error of prediction of 0.027 cm$^3$/cm$^3$ and bias of 0.001 cm$^3$/cm$^3$ for prediction.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.32-37
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• 2003

The amount of 4,500 drums of soil waste are temporarily stored in KAERI. In order to develop a technology for safe treatment of the soil waste, a number of tests were performed by applying cement and polymer as solidifier. Immobilization specimens were adequately made by mixing soil waste with cement or polymer Compressive strength and leaching tests were performed in order to see the fulfillment to standard of disposal following the storage. A compressive strength, about 5,300psi was obtained from both solidifiers of cement containing 40% of soil waste and polymer containing 60%. The obtained leaching index was larger than 11, which was satisfied with the relevant standard. It was shown that the integrity of the solidified waste much depends on homogenization in solidifying process and hardness of the specimen. Volume reduction of solidified waste with polymer was better than that of cement by 20%.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.192-199
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• 2010

This research produced internal model tester ($2.0m{\times}2.0m{\times}1.0m$) to evaluate the field application of Paju Unjeong District water recycling system for small streams eco-friendly river bed disparity method for the first time in Korea and conducted comparative analysis of the Paju Unjeong District water recycling system field test results and infiltration rate result of internal tests by each rainfall intensity following surface material. Infiltration rate result of internal tests concrete pavement by rainfall intensity following surface material, asphalt pavement, bentonite mate, stabilized soil construction and mixed soil construction manifested low infiltration rate. On the contrary, compaction soil, grassland and water permeable packaging materials resulted in significant amount of infiltration rate. As for the field permeability test results, they were manifested similar tendency as indoor permeability test results and they satisfied the standard for standard of water permeability of domestic disparity facility (less than $1.0{\times}10-7cm$/sec). As compaction rate increased, unconfined compression strength increased as well while coefficient of water permeability decreased.

• Journal of the Korean Geosynthetics Society
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• v.11 no.1
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• pp.65-75
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• 2012

Since the modem reinforced soil wall technology was introduced in domestic civil engineering society in the year 1980, the reinforced soil walls have been extensively used because these technologies have advantages such as economical efficiency, graceful appearance, and easy construction. This paper describes the application of reinforced soil wall, design criteria, and construction problems. Many cases of troubles, which include a severe deformation of facing, cracks of facing block, overall sliding failure and so on, have been reported. Inappropriate design and construction management mainly induce these problems. The technological level of design and quantity control for reinforced soil wall is not sufficiently supported to cope with the growth quantity of reinforced soil wall construction market and the increasing number of construction companies. The unified standard design and construction criteria of reinforced soil wall should be established with the detail consideration of overall performance and stability. The quality control of design and construction, and cost of construction must be seriously executed to construct a high quality of reinforced soil wall.

• The Journal of Engineering Geology
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• v.18 no.3
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• pp.311-319
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• 2008

Evaluation of an amplitude domain reflectometry (ADR) type soil moisture sensor as ThetaProbe ML2x using the response of frequency impedance was performed in a variety of soil porous media such as Jumunjin standard sand, weathered granite soil at Sangju area, and weathered gneiss soil at Jangsu area. The tested soils were classified with a dried condition and a wetted condition for comparing with soil volumetric water content under different installed depths of the measurement sensor. In the results the part of measurement rod including one signal rod and three shield rod 6cm in length was found to decrease the variation of measurement output voltage with insert 5cm over into the soil porous media. The measurement output voltage was verified to more stable output voltage under weathered granite soils and weathered gneiss soils contained the fine grain materials such as clay and silt minerals than the gradual grain material like as the standard sands. Therefore, measurement values by soil moisture sensor can be offered the more stable values when an contact volume between soil porous media and measurement sensor increase.