• Journal of the Korean Geotechnical Society
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• v.28 no.2
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• pp.15-21
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• 2012

It is difficult to determine the strength and the permeability of a soil levee quantitatively because the damages of a levee have been evaluated only by visual inspection in Korea. Therefore, it is necessary to develop a simplified measurement device for measuring the strength and permeability of a levee. In this paper, a new in-situ permeability measuring device which can measure strength and permeability based on GWP is developed and its applicability to the field permeability test of a soil levee is introduced. From the laboratory and in-situ experiments, the new measuring device has the potential of measuring the soil permeability simply and accurately.

• Applied Microscopy
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• v.34 no.1
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• pp.23-29
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• 2004

In this study, we introduce the structural analysis of amorphous silica nanoparticles by EF-TEM electron diffraction and in-situ heating experiments. Three diffused rings were observed on the electron diffraction patterns of initial silica nanoparticles, while crystalline spot patterns were gradually appeared during the insitu heating process at $900^{\circ}C$. These patterns indicate the basic unit of $SiO_4$ tetrahedra consisting amorphous silica and gradual crystallization into the ideal layer structure of tridymite by heating. Under high vacuum condition in TEM, SiO nanoparticles were redeposited on the carbon grid after evaporation of SiO gas from $SiO_2$ above $850^{\circ}C$ and the remaining $SiO_2$ were crystallized into orthorhombic tridymite, consistent with ex-situ heating results in furnace at $900^{\circ}C$.

• The Journal of Engineering Geology
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• v.10 no.3
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• pp.225-236
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• 2000

We conducted laboratory simulations of deep vertical drilling into the earth's crust to induce borehole breakouts and investigated their potential use for estimating in situ stress magnitudes in Westerly granite and Berea sandstone. Our experiments consisted of two major stages, a series of triaxial tests and borehole-breakout formation tests under a wide range of far-field stresses. We derived the Mohr-Coulomb, Nadai and Mogi failure criteria from the triaxial test results. Each criterion was compared with the stress condition at breakout boundaries. We concluded that the well known Mohr-Coulomb criterion is not compatible with the stress condition at breakout failure. On the other hand, polyaxial (truly triaxial) failure criteria such as the Nadai criterion for Berea sandstone and the Mogi criterion for Westerly granite were much more suitable for predicting breakout failure zone. Such failure criteria appeared to enable the reliable estimation of the magnitude of one of two horizontal principal stresses if the other one is known.

• Tunnel and Underground Space
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• v.21 no.2
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• pp.117-127
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• 2011

The purpose of this study is to demonstrate the effect of in-situ rock stresses on the deformability and permeability of fractured rocks. Geological data were taken from the site investigation at Forsmark, Sweden, conducted by Swedish Nuclear Fuel and Waste Man-agement Company (SKB). A set of numerical experiments was conducted to determine the equivalent mechanical properties (essentially, elastic moduli and Poisson's ratio) and permeability, using a Discrete Fracture Network-Discrete Element Method (DFN-DEM) approach. The results show that both mechanical properties and permeability are highly dependent on stress because of the hyperbolic nature of the stiffness of fractures, different closure behavior of fractures, and change of fluid pathways caused by deformation. This study shows that proper characterization and consideration of in-situ stress are important not only for boundary conditions of a selected site but also for the understanding of the mechanical and hydraulic behavior of fractured rocks.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.125-134
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• 2006

In order to establish the in-situ application of the artificial storage and recovery (ASR) technology which is used the property of the aquifer storage of groundwater. We carried out to the in-situ experiments such as borehole TV logging, pumping test and artificial hydraulic fracturing in volcanic island, Ulleungdo. In-situ experiments were conducted to divide the before- and after-hydraulic fracturing. Pumping test was achieved to confirm the two fracture zones, GL-13m and GL-21m, which are determined by the borehole TV logging. From the results of the before- and after-pumping tests, the hydraulic connectivity was confirmed to locate at GL-13m in the residual deposit zone of pumice media as alluvium. However, in the bedrock tone at GL-21m the hydraulic connectivity could be considered to faulty. Consequently, in this study area the artificial recharge has a little unsatisfied to geo-structural condition and desired to more detail investigation works.

• Journal of the Korean Geotechnical Society
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• v.25 no.2
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• pp.17-24
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• 2009

Undrained shear strength is estimated from laboratory tests generally, but the very soft or fluid material is generally incompatible with the test setup. In-situ methods require test to be accomplished at discrete time intervals, which does not provide a method to predict strength increment as a function of time for an ongoing project. Therefore, correlation between slump test value and undrained shear strength was derived through the regression analysis of slump test and laboratory vane shear test results. For the reliability of derived correlation equation statistical analysis using the t-distribution was performed and the comparison between the results of in-situ test and laboratory experiments demonstrated the applicability of the derived correlation.

• Journal of Life Science
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• v.19 no.11
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• pp.1538-1546
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• 2009

This study was conducted to estimate the in vitro fermentation characteristics and in situ degradabilities of total mixed rations fermented by the synbiotic co-cultures composed of various anaerobic microorganisms in the rumen of cow. Seventy two TMR bags (4 treatments $\times$ 6 fermentation days $\times$ 3 replications) were manufactured for in vitro and in situ experiments. The experiment was composed of four treatments including the control, the mould and bacteria synbiotics (T1), the mould and yeast synbiotics (T2) and the bacteria and yeast synbiotics (T3). Each treatment had six fermentation days (1, 3, 5, 7, 14, 21 day) with three replications. Two rumen cannulated Holstein cows (550 ㎏ of mean body wt) were used for in situ trial, and a total of 96 nylon bags were retrieved from the rumen according to eight fermentation times (1, 3, 6, 9, 18, 24, 48 and 72 hr). The mean fermentation temperatures of TMRs by supplementation of anaerobic micoorganism co-cultures ranged from $22.97^{\circ}C$ to $26.07^{\circ}C$, and tended to increase steadily during the entire period. pH values of the F-TMRs ranged from 4.39 to 4.98 and tended to decrease with the extension of the fermentation period, and decreased by supplementation of synbiotics (p<0.05). The ammonia concentrations of F-TMRs were not affected by addition of synbiotic co-cultures during the early fermentation period (within 7 days), but was lowest (p<0.05) in T3 during the late fermentation periods (after 14 days). Lactic acid concentration of F-TMR was lowest in T3 at 1 day of fermentation, but was not different from treatments in the other fermentation days. Microbial growth rates of F-TMR reached a peak at 7 days of fermentation, and afterward tended to decrease. In in situ experiment, the DM disappearance rates were higher in T1 than the control during early fermentation times (within 3 hours), but was vice versa at 48 hours of fermentation (p<0.05). There was no significant difference in effective DM degradability among treatments. NDF and ADF disappearance rates in situ were similar to those of DM. From the above results, the supplementation of synbiotics, particularly the mould and bacteria synbiotics, resulted in improving the pH and concentration of lactic acid of F-TMR as parameters of fermentation compare to the control, and also had higher in situ disappearance rates of DM, NDF and ADF than the control at early fermentation time. However, effective DM degradability was not affected by supplementation of synbiotics.

• Korean Journal of Organic Agriculture
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• v.21 no.3
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• pp.437-450
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• 2013

Miscanthus sacchariflorus var. No. 1 has been newly developed in Korea. This study was conducted to assess the feed value of M. sacchariflorus var. No. 1 at different growth and harvesting time. Total 3 different miscanthus - 1y4m (first shoot and harvested at 4 month), 2y4m (second shoot and harvested at 4 month) and 2y8m (second shoot and harvested at 8 month). Two experiments were carried out, In vitro rumen simulated fermentation and In situ dry matter digestibility (DMD). Ruminal pH at in vitro fermentation were higher in M. sacchariflorus var. No. 1 treatments compared to the rice straw (RS). In volatile fatty acid production, 1y4m resulted in higher acetate production than the other M. sacchariflorus var. No. 1 at higher maturity stages. Significant differences among treatments were observed in propionate and total volatile fatty acid (VFA) productions at 9, 24 and 48 h of incubation times. Higher ammonia nitrogen productions were found as increased maturity of M. sacchariflorus var. No. 1. At In situ experiment, high DMD was detected in the order of RS (60.51%) > 1y4m (57.65%) > 2y4m (57.63%) > 2y8m (46.28%). The results from this study indicate that young and early harvested M. sacchariflorus var. No. 1 are able to improve its nutrient values in the ruminant animal.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.24-30
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• 2010

This study utilises repeated numerical tests to understand the effects of variable near-surface conditions on time-lapse seismic surveys. The numerical tests were aimed at reproducing the significant scattering observed in field experiments conducted at the Naylor site in the Otway Basin for the purpose of $CO_2$ sequestration. In particular, the variation of elastic properties of both the top soil and the deeper rugose clay/limestone interface as a function of varying water saturation were investigated. Such tests simulate the measurements conducted in dry and wet seasons and to evaluate the contribution of these seasonal variations to seismic measurements in terms of non-repeatability. Full elastic pre-stack modelling experiments were carried out to quantify these effects and evaluate their individual contributions. The results show that the relatively simple scattering effects of the corrugated near-surface clay/limestone interface can have a profound effect on time-lapse surveys. The experiments also show that the changes in top soil saturation could potentially affect seismic signature even more than the corrugated deeper surface. Overall agreement between numerically predicted and in situ measured normalised root-mean-square (NRMS) differences between repeated (time-lapse) 2D seismic surveys warrant further investigation. Future field studies will include in situ measurements of the elastic properties of the weathered zone through the use of 'micro Vertical Seismic Profiling (VSP)' arrays and very dense refraction surveys. The results of this work may impact on other areas not associated with $CO_2$ sequestration, such as imaging oil production over areas where producing fields suffer from a karstic topography, such as in the Middle East and Australia.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.182-187
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• 2010

In the various fields of Civil Engineering, shear modulus is very important input parameters to design many constructions and to analyze ground behaviors. In general, a shear wave velocity profile is decided by various experiments before constructing a structure and, analysis and design are carried out by using decided shear wave velocity profile of the site. However, if civil structures are started to construct, the shear wave velocity will be increased more than before constructions because of confining pressure increase by the load of structure. The evaluation of the change in shear wave velocity profile is used very importantly when maintaining, managing, reinforcing and regenerating existing structures. In this study, a non-destructively geotechnical investigation method by using the HWAW method is applied to an evaluation of change in properties of the site according to construction. Generally, the space for experiments is narrow when underground of existing or on-going structures is evaluate, so a prompt non-destructive experiment is required. This prompt non-destructive experiment would be performed by various in-situ seismic methods. However, most of in-situ seismic methods need more space for experiments, so it is difficult to be applied. The HWAW method using the Harmonic wavelet transforms, which is based on time-frequency analysis, determines shear wave velocity profile. It consists of a source as well as short receiver spacing that is 1~3m, and is able to determine a shear wave velocity profile from surface to deep depth by one test on a space. As the HWAW method uses only the signal portion of the maximum local signal/noise ratio to determine a profile, it provides reliability shear modulus profile such as under construction or noisy situation by minimizing effects of noise from diverse vibration on a construction site or urban area. To estimate the applicability of the proposed method, field tests were performed in the change of geotechnical properties according to constructing a minimized modeling bent. Through this study, the change of geotechnical properties of the site was effectively evaluated according to construction of a structure.