• Geomechanics and Engineering
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• v.33 no.1
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• pp.113-120
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• 2023

Coastal and offshore structures such as ports and offshore wind farms will often need to be built on fine-grained sediments. Geotechnical properties associated with sediment compressibility are key parameters for marine construction designs especially on soft grounds, which involve clay-mineral dominated fines that can consolidate and settle significantly in response to engineered and environmental loads. We conduct liquid limit tests and 1D consolidation tests with fine-grained soils (silica silt, mica, kaolin and bentonite) and biogenic soils (diatom). The pore fluids for the liquid limit tests include deionized water and a series of brines with NaCl salt concentrations of 0.001 m, 0.01 m, 0.1 m, 0.6 m and 2.0 m, and the pore fluids for the consolidation tests deionized water, 0.01 m, 0.6 m, 2 m. The salt concentrations help the liquid limits of kaolin and bentonite decrease, but those of diatom slightly increase. The silica silt and mica show minimal changes in liquid limit due to salt concentrations. Accordingly, compression indices of soils follow the trend of the liquid limit as the liquid limit determined the initial void ratio of the consolidation test. Diatoms are more likely to be broken than clastic sediments during to loading, and diatom-rich sediment is therefore generally more compressible than clastic-rich sediment.

• Journal of the Korean Ceramic Society
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• v.19 no.2
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• pp.139-144
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• 1982

This study has examined closely on the various foundamental conditions for the fitting in steatite porcelain as a industrial porcelain of superior quality, and as a decorated porcelain. The materials consisting of the Kyul Sung talc, and the sea water magnesia clinker power which was produced from Sam Hwa-Hwa Sung, as major constituents have been used, and also used Hyup Jin kaolin as clay minerals to give them plasticity. First, the mixture was made of corresponding in the theoretical composition of enstatite with Kyul sung talc and sea water magnesia clinker, and kaolin was added in various kinds of 1%, 2.5% 5%, 10%, and 20% by weight of the mixture. Next, the mixture was fired at the various temperatures from 1330 to 145$0^{\circ}C$. After we examined closely the physical properties and microstructures, we achieved the results that noted from this study were listed below. 1. The addition amount of kaolin should generally be from 5% to 10% by weight of the mixture to give mixture plasticity in steatite porcelain, but preferably about 20% to consider the firing temperature. 2. The temperature of the optimum firing range is from 1390 C to 142$0^{\circ}C$. 3. A case, which the $A_2$ composition had been fired at 142$0^{\circ}C$, showed a good effect in the strength, but showed a bad result in the absorption. Therefore, the specimens of $A_4$ the composition has excellent in properties of matters when the composition is fired at 142$0^{\circ}C$. Also, we consider that the specimens of the $A_5$ composition, which is fired at 139$0^{\circ}C$, is suitable for the $MgO-SiO_2$ porcelain bodies with respect to the various properties.

• Korean Journal of Materials Research
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• v.2 no.1
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• pp.3-11
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• 1992

Aluminum sulfate hydrate was prepared using sulfuric acid from Ha-dong kaolin. The effects of calcination-temperature and calcination-time of kaolin, reaction-temperature and reaction-time, and sulfuric acid concentration on the formation of aluminum sulfate hydrate were investigated. The precipitation condition of aluminum sulfate hydrate from sulfuric acid solution was determined. Also, the products heat-treated at different temperatures have been investigated by X-ray diffraction, thermogravimetry, differential thermal analysis, Fourier transform infrared spectrophotometer, scanning electron microscopy, particle size distribution analysis and chemical analysis. In the optimum condition, the conversion of aluminum oxide in kaolin to aluminum sulfate hydrate was 60%. From the results of XRD, TG-DTA, and FT-IR, it is suggested that the aluminum sulfate hydrate is thermally decomposed as follows ; $Al_2(SO_4)_3{\cdot}18H_2O{\rightarrow}Al_2(SO_4)_3{\cdot}6H_2O{\rightarrow}Al_2(SO_4){\rightarrow}\;amorphous\;alumina{\rightarrow}{\gamma}-alumina{\rightarrow}{\delta}-alumina{\rightarrow}{\theta}-alumina{\rightarrow}{\alpha}-alumina$. The purity of alumina powder prepared by calcining aluminum sulfate hydrate at $1200^{\circ}C$ was 99.99 percent.

• Journal of the Korean Geotechnical Society
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• v.21 no.2
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• pp.5-16
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• 2005

Tn this study, model soil deposits are prepared in large test chambers to minimize the scale effects. Also, slurry of mixture containing 50 percent kaolin clay and 50 percent silica has been consolidated to simulate the process of natural soil deposit formation and to reduce the consolidation time. To provide a more detailed description of varying soil properties along the soil profile of model clay deposits and to compare the in-situ test results with those from prototype tests, miniature in-situ tests, including vane shear, piezoprobe, and cone penetration tests were conducted in each of the clay deposits. The current results indicate that consistent soil deposits were prepared for the current and previous test programs. Also, reasonable predicting methods of prototype behavior based on model in-situ test results were suggested in this study by examining differences between the test results from both the model and prototype tests.

• Economic and Environmental Geology
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• v.30 no.2
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• pp.81-87
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• 1997

Chonnam and Kyongsang clay alteration areas are distributed in volcanic fields of the Yuchon Group in late Cretaceous period. The host rock of the Chonnam alteration area is generally acidic and that of the Kyongsang alteration area is acidic to dominantly intermediate volcanics. The important difference of two alteration areas is source of fluid; the Chonnam alteration area is characterized by dominantly meteoric water and the Kyongsang alteration area is characterized by dominantly magmatic water. Accordingly, the high temperature minerals such as pyrophyllite and andalusite, and boron bearing minerals such as dumortierite and tourmaline are common in the Kyongsang alteration area. In contrast to this, the lower temperature minerals such as kaolin and alunite are common in the Chonnam alteration area. The mineralogical difference of two alteration areas were depended on the difference of the formation temperature of clay deposits. The other important geochemical difference is the chemistry of hydrothermal solution such as pH. The alteration of "acid-sulfate type" with alteration mineral assemblage of alunite-kaolin-quartz is dominant in the Chonnam alteration area, which was caused by the attack of strong acid and acid solution. In contrast to this, the that of "quartz-sericite type" with the mineral assemblage of sericite-quartz is dominant in the Kyongsang alteration area, which was caused by the attack of neutral or weak acid solution. Also, the Kyongsang and Chonnam alteration areas show the difference in structural setting; the Chonnam alteration area is commonly associated with silicic domes and the Kyongsang alteration area is commonly associated with calderas.

• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.181-187
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• 2003

This paper describes a study of the influence of shield tunnel construction on the displacements and stresses induced in the linings of existing nearby parallel tunnels. The paper presents a brief review of a set of laboratory scale model research programme investigating the influence of tunnel proximity and alignment, liner stiffness on the nature of the interactions between closely spaced tunnels in clay. A total of two sets of carefully controlled physical model tests were performed. A cylindrical test tank was developed and used to produce clay samples of Speswhite kaolin. In each of the tests, three model tunnels were installed in order to conduct two interaction exts that have been carried out to investigate the interaction problem between parallel tunnels. The results of these tests are compared with the results of finite element analysis to investigate the techniques that must be used to obtain reliable numerical solutions to this type of problem.

• 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.

• Journal of the Mineralogical Society of Korea
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• v.15 no.1
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• pp.1-10
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• 2002

The present study is focused on the granite weathering and soil formation, and the heavy metal contamination in soils in the Onsan industrial area. For profile study, soil sampling was conducted on each depth and experimental analyses have been conducted on those samples. X-ray diffraction analyses show that clay minerals consist mainly of kaolin minerals, vermiculite, and minor illite. Most of kaolin minerals in the lower kiwi of the profile consist of halloysite as confirmed by formamide intercalation, but the content of halloysite decreases gradually toward the surface since it has been transformed to kaolinite in the upper part of the profile. Thermal treatment by heating at $110^{\circ}C,\;300^{\circ}C,\;and\;550^{\circ}C$ shows a diffuse and broad peak the between 10 and $14\;{\AA}$ region in X-ray diffractograms. This suggests the possible existence of the hydroxy-Al interlayerecl vermiculite. Na-citrate extraction method reaconfirms this result showing transition of $14\;{\AA}$ peak to $10\;{\AA}$ In by removing the interlayer materials and restoring the vermiculite to its original state. The occurrence of hydroxy-Al interlayered vermiculite is also supported by soil pH distribution room 3.9 In the lower part to 3.6 in the upper part of the profile. Sequential extraction experiment was conducted to investigate the states of heavy metals in soils. The experiment shows that relatively high amounts of heavy metals are concentrated in the upper part of the profile and that most of them are bound to Fe/Mn oxides and organic matters while less concentration in clay minerals. The result indicates that most of heavy metal pollutants are concentrated in the surface soil and that the low concentrations of heavy metals in clays are mainly due to the low adsorption capacities of clay minerals such as kaolin minerals and hydroxy-Al interlayered vermiculite in acidified soil condition.

• Journal of Korean Society of Forest Science
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• v.90 no.5
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• pp.608-618
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• 2001

To understand the weathering processes of the soil by submicroscopic method is very important to realize the properties of the soils. In this study soil formation processes show every steps to the changes in chemical and mechanical properties and the submicroscopic characteristics of soil weathering on the profiles of forest soils derived from granite in southern part of Korea. Fecal pellets(SEM) are given a full detail of the positive activities of the forest soil animals; mainly invertebrates in the O horizon and the E horizon. External shapes of fecal pellets have been divided into five groups : spherical, ellipsoidal, cylindrical, platy and threadlike. But doughnutlike form of fecal pellets is observed in this study. The soluble and suspended materials in the soils move downwards by percolation from the A horizon to the B or the BC horizons, and result in the illuviation cutans(SEM) on the ped surface of the lower horizon and deposited stack of kaolinite. Illuviated cutans are deposited on the ped surface even in the depth of 312cm in the BC horizon as well as the Bt horizon and comprise of fine silt, coarse clay and fine clay. A lot of halloysites are observed on the cutan surface. Halloysite formation from feldspars has been well known but a lot of hallyosite formation are observed in this study. The formation were predicted by Jackson(1962), inferred by Wada and Kakuto(1983a, b) and proved evidently by Cho and Mermut(1992a, b). This also suggests that halloysites in the soils derived from granite are formed a lot from ferruginous chlorites. The release of Fe from the chlorite structure are significant pedogenic processes and newly formed Fe oxides imparted a red color to the soils. The iron oxides particles, which are ejected and recrystalized, aggregate thickly on the edge of the ferruginous chlorites, and this indicates the release of structural Fe from weathered chlorites. Hematites and goethites are frequent in the fine clay in this soils.

• Journal of the Korean Chemical Society
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• v.10 no.2
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• pp.67-75
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• 1966

Four kinds of clays from Sinyewon mine which is located in Chungchoungnam-Do district and two kinds of Japanese clays (Gairome, Kibushi) were selected and studied on the fundamental properties of these clays and those which are refined by the elutriation method. Chemical analysis, grading analysis such as refractoriness, specific gravity, color, fired color and plasticity, particle size distribution, various thermal tests, X-ray diffraction analysis and electron microscopic survey were carried out on these clays. The comparison of domestic clays with Japanese clays was made. 1. In chemical composition and physical properties, these four kinds of Sinyewon clays are almost similar to each other and also to Gairome and Kibushi clays. In refractoriness, Gairome and Kibushi clays have relatively high value such as SK 34 and 35, while Sinyewon clays have the value of about SK 32. Especially Sinyewon clay B has the low refractoriness (SK 18) and plasticity. Refined clays have the tendency of somewhat higher value than crude ones in refractoriness. 2. When burnt up to $900^{\circ}C$, the coefficients of contraction of Sinyewon clays were under 1.5%, Gairome under 1.3%, Kibushi under 3.0%. Only Sinyewon clay B showed expansion (1.0%) instead of contraction. 3. X-ray diffraction analysis and electron micrography showed that all of four Sinyewon clays and two Japanese clays are mainly composed of poorly crystallized kaolin, containing small amount of halloysite, sericite and considerable amount of quartz and feldspar. Sinyewon clay B contains especially large amount of quartz and feldspar. In general, it has been found out that the refined clays were free from large amount of iron oxide, quartz and feldspar.