• Journal of the Korean Geotechnical Society
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• v.20 no.9
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• pp.155-166
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• 2004

The characteristics of soft clays are very important for the land development plan. This study is to investigate correlations between the engineering properties and the characteristics of clay minerals of the undisturbed clay samples obtained from Sihwa area. This study included X-Ray diffraction analysis, X-Ray fluorescence spectrometer analysis, scanning electron microscopy analysis and energy dispersive X-Ray spectrometer analysis. The correlations between the clay mineral properties and the laboratory and field testing results were investigated. The characteristics of soft clay in Sihwa area were compared with those in Yangsan and Kunsan area.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.15 no.2
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• pp.127-137
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• 2003

The researches on the construction of artificial coastal wetlands have been progressed in order to cope with the situation that the area of Korean tidal flat has been reduced due to several coastal developments This study, as a part of the project on construction of the artificial tidal flats, deals with the comparison of the geotechnical characteristics between natural tidal flat and artificial tidal flat, and is also focused on the stability analysis of tidal flats. Various laboratory tests were performed using disturbed and undisturbed samples, which were obtained from a sandy tidal flat in Korea. The stability of the sandy soils accumulated on the tidal flat was investigated by comparing the shear strength of soil evaluated from laboratory test with induced shear stress due to both current and wave action.

• Journal of the Korean Geotechnical Society
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• v.20 no.1
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• pp.75-82
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• 2004

To evaluate the characteristics of permeability in weathered residual soil, flexible wall permeameter tests are performed using undisturbed samples. The Influence of hydraulic gradient and confining pressure on the permeability of weathered residual soil is analyzed. To compare the characteristics of permeability between weathered soil and sand, similar tests are performed using Jumoonjin sand. Also, piping model tests are performed to investigate the piping resistance of weathered residual soil. As a result, weathered residual soil shows very dependable permeability on hydraulic gradient and very large resisting ability against piping compared with sand.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.9
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• pp.995-1000
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• 2016

The maximum cross-correntropy (MCC) algorithm with a set of random symbols keeps its optimum weights undisturbed from impulsive noise unlike MSE-based algorithms and its main factor has been known to be the input magnitude controller (IMC) that adjusts the input intensity according to error power. In this paper, a normalization of the step size of the MCC algorithm by the power of IMC output is proposed. The IMC output power is tracked recursively through a single-pole low-pass filter. In the simulation under impulsive noise with two different multipath channels, the steady state MSE and convergence speed of the proposed algorithm is found to be enhanced by about 1 dB and 500 samples, respectively, compared to the conventional MCC algorithm.

• Geomechanics and Engineering
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• v.30 no.5
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• pp.437-448
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• 2022

Alluvial soil is challenging to work with due to its high compressibility. Thus, consolidation settlement of this type of soil should be accurately estimated. Accurate estimation of the consolidation settlement of alluvial soil requires accurate prediction of compressibility parameters. Geotechnical engineers usually use empirical correlations to estimate these compressibility parameters. However, no attempts have been made to develop correlations to estimate compressibility parameters of alluvial soil. Thus, this paper aims to develop new models to predict the compression and recompression indices (Cc and Cr) of alluvial soils. As part of the study, geotechnical laboratory tests have been conducted on large number of undisturbed samples of local alluvial soil. The obtained results from these tests in addition to available results from the literature from different parts in the world have been compiled to form the database of this study. This database is then employed to examine the accuracy of the available empirical correlations of the compressibility parameters and to develop the new models to estimate the compressibility parameters using the nonlinear regression analysis. The accuracy of the new models has been accessed using mean absolute error, root mean square error, mean, percentage of predictions with error range of ±20%, percentage of predictions with error range of ±30%, and coefficient of determination. It was found that the new models outperform the available correlations. Thus, these models can be used by geotechnical engineers with more confidence to predict Cc and Cr.

• Journal of the Korean Geotechnical Society
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• v.22 no.11
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• pp.133-142
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• 2006

Pusan clay, which is distributed in the Nakdong River estuary, is unusually soft and thick compared with other clays in the world. Because the consolidation settlement of the clay was significantly underestimated in several recent reclamation projects, it has been emphasized particularly on the need of studying the permeability characteristics. This study carries out vertical and horizontal permeability tests on undisturbed and consolidated samples from two sites of the area. The results of the study show the peculiar permeability anisotropy and the relationships with other indexes on Pusan clay and also comparison with those of other world clays.

• Journal of the Korean Geotechnical Society
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• v.18 no.4
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• pp.85-93
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• 2002

This study presented a new method for evaluating the coefficient of consolidation by using inflection point method which was based on the fact that time factor, T corresponding to the inflection point of a semi-logarithmic plot of a time curve is fixed and equals to T = 0.405 at 70.03% consolidation. In the proposed method, as the next load increment is applied as soon as the inflection point is confirmed, the time required to identify the inflection point can be shortened. Thus, the coefficient of consolidation may be easily evaluated. The time required to complete the testing using this rapid consolidation method could be as low as 0.5~9 hours compared with 1 or 2 weeks in the case of the conventional consolidation test. For this study, we designed settlement equipment for normalization of test samples. In test results, the factors of consolidation agreed with undisturbed samples results.

• Geomechanics and Engineering
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• v.7 no.6
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• pp.589-612
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• 2014

This study includes determination of liquefaction potential in Erzincan city center. Erzincan Province is situated within first-degree earthquake zone on earthquake map of Turkey. In this context, the earthquake scenarios were produced using the empirical expressions. Liquefaction potential for different earthquake magnitudes (6.0, 6.5, 7.0) were determined. Liquefaction potential was investigated using Standard Penetration Test (SPT). Liquefaction potential analyses are determined in two steps: geotechnical investigations and calculations. In the first steps, boreholes were drilled to obtain disturbed and undisturbed soil samples and SPT values were obtained. Laboratory tests were made to identify geotechnical properties of soil samples. In the second step, liquefaction potential analyses were examined using two methods, namely Seed and Idriss (1971), Iwasaki et al. (1981). The liquefaction potential broadly classified into three categories, namely non-liquefiable, marginally liquefiable and liquefiable regions. Additionally, the liquefaction potential index classified into four categories, namely non-liquefiable, low, high and very high liquefiable regions. In order to liquefaction analysis complete within a short time, MATLAB program were prepared. Following the analyses, liquefaction potential index is investigated by Iwasaki et al. (1982) methods. At the final stage of this study, liquefaction potential maps and liquefaction potential index maps of the all study area by using IDW (inverse distance weighted) interpolation method in Geostatistical Analyst Module of ArcGIS 10.0 Software were prepared for different earthquake magnitudes and different depths. The results of soil liquefaction potential were evaluated in ArcGIS to map the distributions of drillings with liquefaction potential. The maps showed that there is a spatial variability in the results obtained which made it difficult to clearly separate between regional areas of high or low potential to liquefy. However, this study indicates that the presence of ground water and sandy-silty soils increases the liquefaction potential with the seismic features of the region.

• Korean Journal of Food Science and Technology
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• v.32 no.4
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• pp.974-978
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• 2000

The vane method was used to measure yield stresses of five commercial kochujang samples under a controlled shear-rate operating condition. Magnitudes of vane yield stress were higher than those of yield stress using Casson model with a concentric cylinder viscometer. Magnitudes of vane yield stresses showed great differences between the static $({\sigma}_s)$ and dynamic yield stresses $({\sigma}_d)$ of kochujang samples with undisturbed structure (UDS) and with broken down structure (BDS). A dimensionless yield number $(N{\sigma}_o)$ was determined from the ratio of ${\sigma}s$ to ${\sigma}d$ in order to describe the existence of temporary structure of kochujang.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.455-465
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• 2006

In this study, the effect of scour was evaluated by regional and geotechnical characteristics and back data were accumulate for the design against scour through the local erosion characteristics evaluation of the Inchon coast. The erosion characteristics for the undisturbed soil samples collected near the main locations at the Incheon 2nd bridge, the Hwangyeong bridge, and a coast road in Songdo, are determined quantitatively through the scour rate tests. On the basic soil properties test, the bed around the Inchon coast chiefly consists of fined grained soils, and the soil samples were classified as silty clay(ML) or clay(CL) under the Unified Soil Classification System. On the scour rate test, the critical shear stress increases when the undrained shear strength increases as of the general trend of fine grained soils, and the average scour rate for the maximum velocity by 100 year flood is 173mm/hr at the Incheon 2nd bridge, 67mm/hr at the Hwangyeong bridge and 10mm/hr at a coast road in Songdo, respectively. Comparing to the scour rate of coarse grained soil, that of the bed around the Inchon coast is turned out to be very low. Therefore, the relative ability of the bed around the Inchon coast to resist erosion is assumed to be very high.