• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.591-596
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• 2001

The purpose of this paper Is to present and discuss some of evaporation and desiccation observed in laboratory experiments under controlled conditions, and is to improve PTM(Progressive Trenching Method) operating technique. PTM is the technically feasible and economically justifiable dewatering and desiccation technique for dredged material containment areas. A series of laboratory experiments with large model test were carried out to get evaporation rate and strength increase. Surface desiccation of dredged material is basically changed by evaporation characteristics which is controlled by weather and trench type, etc. This study shows that trench depth and rain fall are important factors in desiccation of dredged soft clay.

• Proceedings of the Korean Geotechical Society Conference
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• 1991.10a
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• pp.87-102
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• 1991

It has been reported that the failure of Carsington Dam in Eng1and occured due to the existence of a thin yellow clay layer which was not identified during the design work, and due to pre-existing shears of the clay layer. The slope stability analyses during the design work, which utilized traditional circular arc type failure method and neglected the existence of the clay layer, showed a safety factor of 1.4. However, the post-failure analyses which utilized translational failure mode considering the clay layer and the pre-existing shear deformation revealed the reduction of safety factor to unity. The post-failure analysis assumed 10。 inclination of the horizontal forces onto each slice based on the results of finite element analyses. In this paper, Bishop's simplified method, Janbu method, and Morgenstern-Price method were used for the comparison of both circular and translational failure analysis methods. The effects of the pre-existing shears and subsquent movement were also considered by varying the soil strength parameters and the pore pressure ratio according to the given soi1 parameters. The results showed factor of safefy 1.387 by Bishop's simplified method(STABL) which assumed circular arc failure surface and disregarding yellow clay layer and pre-failure material properties. Also the results showed factor of safety 1.093 by Janbu method(STABL) and 0.969 by Morgenstern-Price method(MALE) which assumed wedge failure surface and considerd yellow clay layer using post failure material properties. In addition, dam behavior was simulated by Cam-Clay model FEM program. The effects of pore pressure changes with loading and consolidation, and strength reduction near or at failure were also considered based on properly assumed stress-strain relationship and pore pressure characteristics. The results showed that the failure was initiated at the yellow clay layer and propagated through other zones by showing that stress and displacement were concentrated at the yel1ow clay layer.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.349-356
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• 2003

Almost every material of PVD (Prefabricated Vertical Drain) has the fatal problem on the condition - the length must shorten with the settlement of the surrounding grounds - which all PVDs must satisfy. Kinking deformation by buckling of PVD due to consolidation settlement Is discussed in this paper. A new testing device to clarify the deformation of PVD under consolidation of surrounding clay was developed and the fiber drain and a PVD made of plastics were compared under the same condition of consolidation using natural clay specimens. The results are also shown in this paper.

• Journal of Industrial Technology
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• v.17
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• pp.103-110
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• 1997

This thesis is to investigate the one-dimensional consolidation behavior of soft marine clay with uniform surcharges by perfoming numerical and experimental works. Parametric experimental works of centrifuge model test were carried out changing test conditions of gravitational level in centrifuge, magnitude of surcharges and construction sequence of applying surcharges. Results of centrifuge model experiments were analyzed by using the numerical technique of explicit finite difference method based on the finite strain consolidation theory, being known to be appropriate to analyze the consolidational behavior of soft clay with a very high initial void ratio using the Lagrangian and the material coordinate systems. Test results were in relatively good agreements with analyzed results in terms of excess pore pressure dissipation and consolidation settlement with time and final void ratio distribution.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.473-485
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• 2010

Lightweight materials using in-situ clay soil contain large amounts of fine grain and cement for increasing the strength, lighter weight to increase liquidity for the foam and the bulk of the material is conducted by the water. Domestic cases, Light weight soil to improve cementation and lightness using demountable mixing device is defined Smartsoil. Typical features are their self-leveling, self-compaction, folwability. By adjusting the amount of cement, the strength can be controlled artificially. And re-excavation is easy. In this paper, pre-loading method using the road due to the displacement of adjacent structures under construction as an alternative SmartSoil introduces the design and construction practices. Is to discuss and improve.

• Proceedings of the Polymer Society of Korea Conference
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• 2006.10a
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• pp.291-291
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• 2006

Two different sources of clay, Na-Bentonite (Thai local clay) and Na-Montmorillonite were modified with Hexadodeccyltrimethyl ammonium bromide. The nanocomposites of polypropylene were successfully prepared via melt blending in a co-rotating twin screw extruder by using PP-g-MA as a compatibilizer at various contents of organoclays. The morphology of nanocomposites was investigated by using XRD and SEM. The results showed that the intercalated and exfoliated structures were obtained. The thermal behavior was also studied by using DSC and TGA. The degradation temperature of filled PP was greater than that of unfilled PP by 20%. And, the tensile strength and modulus were improved when a small amount of organoclays were added.

• Korea-Australia Rheology Journal
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• v.16 no.4
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• pp.193-199
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• 2004

Poly(o-ethoxy)aniline (PEOA)/organoclay nanocomposite was prepared via a solvent intercalation using chloroform as a cosolvent with organically modified montmorillonite (OMMT) clay. The PEOA initially synthesized from a chemical oxidation polymerization in an acidic condition at pH = 1 was intercalated into interlayers of the clay with $25\;wt{\%}$ clay content. Electrical conductivity of the PEOA/OMMT nano­composite was found to be controlled via the intercalating process. The synthesized PEOA/OMMT nano­composite was characterized via an XRD and a TGA, and then adopted as an electrorheological (ER) material. The PEOA/OMMT synthesized with controllable electrical conductivity without a dedoping pro­cess was found to show typical ER characteristics possessing a yield stress from both steady state and dynamic measurements under an applied electric field.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.10a
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• pp.129-134
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• 2000

Hardening agent has been the traditional material for surface soil stabilization a sat ground This study aims at determining optimal mixture ratio of hardening agent in accordance with the required design specificutions. Hardening agent is properly mixed with Fly ash, Gyosum, Slag and Cement for the etmmngite hydrates which is dective for early stabilization of unconsoliokrred soil. \ulcornerhe treated soil is the clay tint is widely found here and there in Koresz In this study, preliminary tests were performed to get optirml mixture ratio of stabilizer ingredient, and mrvine clay in Jin-Hae was used to get physid and Md properties. Labomtory tests of 50 stabilized soil were performed to get optimal mixture mtio for 16-stabilizer merial a 6 types, a d stabilizer mixing was determined

• International Journal of Precision Engineering and Manufacturing
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• v.9 no.4
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• pp.63-65
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• 2008

The increased interest in reducing the environmental effects caused by releasing organic compounds and aqueous waste has motivated the development of polymeric materials in supercritical fluids. Recently, supercritical fluids have been used in material synthesis and processing because of their special properties, such as high diffusivity, low viscosity, and low surface tension. Supercritical carbon dioxide is the most attractive because it is non-toxic, non-flammable, and has moderate critical temperature and critical pressure values. Supercritical carbon dioxide can also swell most polymers. In this study, we prepared polymer/clay nanocomposites using supercritical fluids. Cloisites 10A, 15A, 25A, and 30B used in this study are montmorillonites modified with a quaternary ammonium salt. The nanocomposites of polymer/clay were characterized by X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry.

• Elastomers and Composites
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• v.54 no.3
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• pp.201-208
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• 2019

Superabsorbent hydrogel (SAH) is a lightly crosslinked hydrophilic functional polymer material comprising a flexible chain structure, which can absorb and retain high amounts of water or aqueous fluids even under high pressure. Therefore, it is important to improve their characteristics such as absorption performance, residual monomer content, and water permeability. SAH nanocomposites were prepared using clay mineral as an inorganic filler and the influence of post-treatment processes such as quenching and aging process on their properties was studied. In addition, surface-crosslinking process was applied to improve the absorption performance associated with mechanical properties and water permeability. The structure of the SAH was characterized using attenuated total reflectance Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy.