• Korean Journal of Soil Science and Fertilizer
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• v.48 no.1
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• pp.1-7
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• 2015

Global population is expected to reach nine billion in 2050 and the total demand for food is expected to increase approximately by 60 percent by 2050 as compared to 2005. Therefore, it is important to increase crop production in order to meet the global demand for food. Slow release fertilizers have been developed and designed in order to improve the efficiency of fertilizers. Mineral-based slow release fertilizers are useful because the minerals have a crystalline structure and are environmentally friendly in a soil. This review focuses on slow release fertilizers based on montmorillonite, zeolite, and layered double hydroxide phases as a host for nutrients, especially N. Urea was successfully stabilized in the interlayer space of montmorillonite by the formation of urea-Mg or Ca complex, $[(Urea)_6Mg\;or\;Ca]^{2+}$ protecting its rapid degradation in soils. Naturally occurring zeolites occluded with ammonium nitrate and potassium nitrate by molten salt treatment could be used as slow release fertilizer because the occlusion process increased the capacity of zeolites to store nutrients in addition to exchangeable cations. Additionally, surface-modified zeolites could also be used as slow release fertilizer because the modified surface showed high affinity for anionic nutrients such as nitrate and phosphate. Moreover, there were attempts to develop and use synthetic layered double hydroxide as a carrier of nitrate because it has positively charged layers which electrostatically bond nitrate anions. Kaolin was also tested by combining with a polymer or through the mechanical-chemical process for slow release of nutrients.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.183-185
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• 2004

In this study, the combined electrokinetic and ultrasonic remediation technique, ultrasonically enhanced electrokinetic technique, was studied for the removal of heavy metal and organic substance in contaminated soils. The electrokinetic technique has been applied to remove mainly the heavy metal and the ultrasonic technique has been to remove mainly organic substance in contaminated soil. The laboratory soil flushing tests combined electrokinetic and ultrasonic technique were conducted using specially designed and fabricated devices to determine the effect of these both techniques. A series of laboratory experiments involving the simple, electrokinetic, ultrasonic, and electrokinetic & ultrasonic flushing test were carried out. A soil admixed with sand and kaolin was used as a test specimen, and Pb and ethylene glycol were used as contaminants of heavy metal and organic substance. An increase in out flow, permeability and contaminant removal rate was observed in electrokinetic and ultrasonic flushing tests. Some practical implications of these results are discussed in terms of technical feasibility of in situ implementation of electrokinetic ultrasonic remediation technique.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.04a
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• pp.202-205
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• 2001

In this study, the electrokinetic remediation test for the kaolin contaminated by lead was performed and voltage, zeta potential, pH distribution, current, contamination transport in soil sample were studied and finite differential numerical analysis program(HERP) for a contaminated soil were compared with those of test. From the result of HERP, in the anode it was represented that the rest concentration was decreased with the voltage. Hence, if treatment time was continued for a long in the constant voltage, comparing with sample having no change in the rest concentration, it is considered that the voltage gradient is the control factor of the rest concentration.

• Journal of the Korean Ceramic Society
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• v.52 no.2
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• pp.150-153
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• 2015

Recently, research on geopolymeric concrete that does not use cement as a binder has been actively investigated. Geopolymeric concrete is cement-free concrete. Masato, ocher and/or soil has been solidified into geopolymeric concrete by the reaction of specifically modified silicate as an alkali activator and inorganic binding materials such as blast furnace slag, fly ash or meta-kaolin, which is cured at room temperature to exhibit high compressive strengths. Based on the results, this study shows how geopolymeric concrete that uses specifically modified silicate and inorganic binding materials is implemented as eco-cement with no cement.

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.2
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• pp.89-97
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• 1986

To clarify the soil characteristics and genesis of the clayey terrace soils in Yeongnam area, the study were carried out with 9 typifying pedons of toposequential terrace soils in Yeongcheon (inland area) and Yeongil (coastal area) region. The results of soil genesis oriented investigations on soil mineralogical compositions and weathering characteristics were summarized as follows; 1. The contents of heavy minerals contained in sand fraction of the terrace soils were less than 5%, but the content in soil layers considered to be originated from other than terrace deposits had 9.8-16.2%. The content of feldspars in light minerals were higher in Yeongcheon sequence while the Yeongil sequence were characterized by having higher content in quartz. The ratios of quartz/feldspars in the soil layers where expecting lithological discontinuity, were different from that of terrace deposits. 2. The resistate index of maturity ranged around 76.7-29.9 in Yeongcheon area and around 85.6-67.2 in Yeongil area. The indices increased with the elevations of terraces. 3. The molar ratios of $SiO_2/Al_2O_3$ in clay fraction were around 1.93-2.65. The parent materials of the terrace deposits judged by the ratios of $Al_2O_3/TiO_2$ and $Fe_2O_3/Al_2O_3$ were considered to be the felsic materials. 4. The compositions of clay minerals detected by X-ray diffractogram and D.T.A. thermogram were dominated by kaolin and illite with subsidiary minerals of vermiculite, quartz, vermiculite intergrading to illite etc. It was distinguished from terrace deposits that by having higher amount of kaolin and montmorin minerals in the substrata of Bancheon soils in Yeongcheon area and Upyeong soils in Yeongil area, respectively.

• Journal of the Mineralogical Society of Korea
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• v.14 no.1
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• pp.58-72
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• 2001

The Cretaceous granite, andesite and sedimentary rocks are widely distributed in the northern Pusan area. The present study investigates mineralogical and geochemical charateristics of residual and cultivated soils derived from these rocks. The soils of granite area contain a large amount of quartz relative to clay minerals, whereas the soils of the andesite area contain more clay minerals than quartz. Clay minerals consist mainly of kaolin minerals illite hydroxy interlayered vermiculite interstratified mica/vermiculite and chlorite. Kaolin minerals are abundant in paddy soils while illite is abundant in less weathered soils. Si and K are major elements in the soils of granite area while Fe and Al in the soils of andesite area. In all the soils Ca, Mg and Na were generally depleted in comparison to those in parent rocks. Analysis data of trace element show that the enrichment pattern in soils depends on parent rock type with high oncentration of some elements over 100 ppm: Ba and Rb in granite area Zn, Bn, and V in andesite area, and Ba and V in sedimentary rock. In granite area, Rb and Th were greatly enriched in soil than in parent rocks. However, Cr, Ni and Sr commonly decrease, whereas Pb increases in all the soils. Exchangeable cation capacity(CEC) is relatively high in the soils of andesite are including abundant clay minerals. Collective evidences prove that the mineralogical and chemical compositions of soils are strongly dependent on the parent rock type. The mineralogy and chemistry of long cultivated soils are not significantly different from those of residual soils.

• Journal of Soil and Groundwater Environment
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• v.6 no.4
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• pp.13-23
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• 2001

In this study, the characteristics of pH variations and contaminant distribution in soil are investigated during electrokinetic treatment for the purpose of restoring contaminated soil with heavy metal. For these objects, laboratory test for the kaolin contaminated by lead was performed. During electrokinetic treatment, lead was transported from anode to cathode. And 75% of lead removed within 80% region of the specimen. Most lead, however, that transported from anode to cathode precipitated in the vicinity of cathode compartment, thus the amount of lead removed by electroosmosis was little. Electrokinetic treatment satisfied regulation criteria of Korean Soil Environment Conservation Law within almost region of the specimen. But enhancement methods can be regarded as inevitable requisite for the cathode region.

• Ocean Systems Engineering
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• v.7 no.2
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• pp.107-120
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• 2017

Spud-can is used for fixing jack-up rig on seabed. It needs to be inserted up to the required depth during the installation process to secure enough soil reaction and prevent overturning accidents. On the other hand, it should be extracted from seabed soils as fast as possible during the extraction process to minimize the corresponding operational cost. To achieve such goals, spud-can may be equipped with water-jetting system including monitoring and control. To develop such a smart spud-can, a reliable numerical simulation tool is essential and it has also to be validated against physical model tests. In this regard, authors developed a numerical simulation tool by using a commercial program ANSYS with extended Drucker-Prager (EDP) formula. Authors also conducted small-scale (1/100) physical model tests for verification and calibration purpose. By using the numerical model, a systematic parametric study is conducted both for sand and K(kaolin)-clay with varying important soil parameters and the best estimated soil properties of the physical test are deduced. Then, by using the selected soil properties, the numerical and experimental results for a sand/K-clay multi-layer case are cross-checked to show reasonably good agreement. The validated numerical model will be useful in the next-stage study which includes controllable water-jetting.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.971-980
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• 2010

Evaluation of permeability and coefficient of consolidation of clayey sand is critical to analyze ground stability or environmental problems such as diffusion and dispersion in groundwater flow. Permeability tests using a flexible wall permeameter were performed to derive the coefficient of consolidation and permeability of reconstituted soil samples with various mixing ratios of kaolin clays and two different types of sands, Jumunjin sand and Ottawa sand. The test results indicated that coefficient of consolidation and permeability in log scale have linear relationships with clay contents in low clay mixing ratio. It is also recognized that coefficient of consolidation and permeability of sand and clay mixture are also dependent on the soil structure.

• Journal of Korea Soil Environment Society
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• v.5 no.1
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• pp.25-32
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• 2000

The electrokinetic apparatus for remediation of the soil contaminated with $Sr^{2+}$ was designed. After kaolin clay compulsorily contaminated by $Sr^{2+}$ solution, the remediation characteristics by electrokinetic method were analyzed. Meanwhile. the numerical code for analysis of electrokinetic migration was developed for modelling of the soil remediation. And the input parameters needed for modelling were measured by laboratory experiment or taken from literature. Experimental results are as follows: After 3 day remidiation under 40 voltage, the front part of experimental cell was almost decontaminated, but the behind part didnt almost be decontaminated. Consequently. the total remediation ratio of $Sr^{2+}$ from cell soil was about 42.6%. Also, the total $Sr^{2+}$remediation ratio from cell soil was about 84.8% after 6 days. The values calculated by the developed code almost agreed with experimental values When voltages of electrode were increased by 10, 30, 40V, the total $Sr^{2+}$ remediation ratlos were about 21.9%. 43.3%, 84.8%, respectively, after 6 days.