• Korean Journal of Soil Science and Fertilizer
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• v.44 no.1
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• pp.58-66
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• 2011

Arsenic pollution is a serious global concern which affects all life forms. Being a toxic metalloid, the continued search for appropriate technologies for its remediation is needed. Phytoremediation, the use of green plants, is not only a low cost but also an environmentally friendly approach for metal uptake and stabilization. However, its application is limited by slow plant growth which is further aggravated by the phytotoxic effect of the pollutant. Attempts to address these constraints were done by exploiting plant-microbe interactions which offers more advantages for phytoremediation. Several bacterial mechanisms that can increase the efficiency of phytoremediation of As are nitrogen fixation, phosphate solubilization, siderophore production, ACC deaminase activity and growth regulator production. Many have been reported for other metals, but few for arsenic. This mini-review attempts to present what has been done so far in exploring plants and their rhizosphere microbiota and some genetic manipulations to increase the efficiency of arsenic soil phytoremediation.

• Journal of the Korean Geotechnical Society
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• v.27 no.3
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• pp.95-102
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• 2011

A model of solid-water-air coupling in triphasic mixture is compared to that of solid-water coupling in biphasic mixture with an application to partially saturated soils. Based on thermodynamics, the mathematical framework governing the behavior of a partially saturated soil is derived by using balance equations, and numerical implementation through drainage experiment of a sand column is carried out to validate the obtained formulations. The role of the air phase in the hydro-mechanical behavior of triphasic mixture can be analyzed from the interaction among phases and from the solid skeleton's constitutive behavior, and the three-phase model found applications in geotechnical engineering problems, such as $CO_2$ sequestration and air storage in an aquifer.

• Water for future
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• v.27 no.2
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• pp.129-137
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• 1994

The surface hydrology of large land areas is susceptible to several preferred stable states with transitions between stable states induced y stochastic fluctuation. This comes about due to the close coupling of land surface and atmospheric interaction. An interesting and important issue is the duration of residence in each mode. Mean transtion times between the stable modes are analyzed for different model parameters or climatic types. In an example situation of this differential equation exhibits a bimodal probability distribution of soil moisture states. Uncertainty analysis regarding the model parameters is performed using a Monte-Carlo simulation method. The method developed in this research may reveal some important characteristics of soil moisture or precipitation over a large area, in particular, those relating to abrupt changes in soil moisture or precipitation having extremely variable duration.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.17-22
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• 2009

Reliability analyses were performed to quantify the risk in axially loaded large-scale pile foundations in consideration of pile-soil interaction and uncertainties on various design variables. The finite difference method based on an equivalent soil spring model and a load transfer method and Monte Carlo simulation method are integrated in the framework of reliabilty analysis. The applicability and efficiency of the proposed method in the safety assessment of axially loaded pile-soil system was verified using a realistic example. Since the proposed method can explicitly consider uncertainties in various design variables, and quantify failure probability of a pile foundation, it can be used to estimate risk, to obtain basic informations for life cycle cost analysis, and to develop code requirements for a reliability-based design of pile foundations.

• Journal of Biosystems Engineering
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• v.25 no.3
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• pp.179-186
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• 2000

Interactions between wheel lug surfaces and soil were analyzed through wheel motion. In this paper, lug surfaces such as trailing and leading lug sides and a lug face were analyzed and reported. The interactions between the surfaces and soil were expressed as the horizontal and vertical directions of resultant forces acting on the surfaces. There analysis indicated qualitatively that (1) the trailing lug side is mainly related to produce motion resistance and reaction to dynamic load, (2) the lug face is related to produce not only the motion resistance, the reaction to the dynamic load but also the traction and (3) the leading lug side is mainly related to produce the traction and the reaction to the dynamic load. Experiments were conducted to prove the results of the motion analysis. Normal and tangential forces acting on the surfaces were measured, and the traction, the motion resistance and the reaction to the dynamic load were calculated with wheel rotational and lug design angles. The experiments proved that the results of wheel motion analyses above mentioned as (1), (2) and obtained from the analysis were correct.

• Geomechanics and Engineering
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• v.17 no.6
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• pp.583-595
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• 2019

In this paper, a comprehensive investigation of the dynamic response of a long-bridge subjected to spatially varying earthquake ground motions (SVEGM) is performed based on a proposed analytical model which includes the effect of soil-structure interaction (SSI). The spatial variability of ground motions is simulated by the powerful record generator, SIMQKE II. Modeling of the SSI in the system is simplified by replacing the pile foundations and soil with sets of independent equivalent linear springs and dashpots along the pile groups. One of the most fundamental objectives of this study is to examine how well the proposed model simulates the dynamic response of a bridge system. For this purpose, the baseline data required for the evaluation process is derived from analyzing a 3D numerical model of the bridge system which is validated in this paper. To emphasize the importance of the SVEGM and SSI, bridge responses are also determined for the uniform ground motion and fixed base cases. This study proposing a compatible analytical model concerns the relative importance of the SSI and SVEGM and shows that these effects cannot be neglected in the seismic analysis of long-bridges.

• Structural Engineering and Mechanics
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• v.89 no.2
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• pp.121-133
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• 2024

In this paper, the performance of under-foundation isolators against generally annoying train-induced vibrations was examined experimentally. The effect of foundation type on the efficacy of such isolators was investigated for the first time. To this end, laboratory models including a soil container, soil, building with three types of foundation (i.e., single, strip, and mat), and isolator layer were employed. Through various dynamic tests, the effects of foundation type, isolation frequency, and the dominant frequency of train load on the isolator's performance were studied. The results demonstrated that the vibration level in the unisolated building with the strip and mat foundation was, respectively, 29 and 38% lower than in the building with the single foundation. However, the efficacy of the isolator in the building with the single foundation was, respectively, 21 and 40% higher than in the building with the strip and mat foundation. Furthermore, a lower isolation frequency and a higher excitation frequency resulted in greater isolator efficacy. The best vibration suppression occurred when the excitation frequency was close to the floor's natural frequency.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.6
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• pp.877-881
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• 2012

This research was carried out to investigate the interaction effect of slope gradient and rainfall intensity on soil loss with rainfall simulator. The soils used in this experiment were saprolite, Chahang series which distributed extensively in Daegwanryong. Slope gradient applied was 0.5, 7, 15 and 30%. Rainfall intensity applied was 20, 60 and $90mm\;hr^{-1}$. The result obtained can be summarised as follow; Overall, Chahang series suffered more losses than saprolite. Chahang series shows the immediately large increase of soil loss with the increasing soil gradient and rainfall intensity. However, saprolite shows a little increasing loss up to 7% gradient and abruptly increasing loss logarithmically over 7% gradient in soil slope. In combination of slope gradient 15, 30% and rainfall intensity 60, $90mm\;hr^{-1}$ processing, both soil erosion happened significantly. And there was no significant difference between the two soils. Because Chahang series have the danger of soil loss with low slope gradient and rainfall intensity, we should give greater attention to soil management in Chahang series.

• Journal of the Korean Geotechnical Society
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• v.34 no.9
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• pp.33-42
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• 2018

When an off-road tracked vehicle travels, an engine thrust that is transmitted to the continuous track induces a shearing action on the soil-track interface. Consequently, the relative displacement known as slip displacement takes place on the soil-track interface, which develops an associated soil thrust acting as a traction force. For the loose or soft ground conditions, an excessively large slip displacement can be required for the development of the desired soil thrust which will make the tracked vehicle mobile and therefore the outer surface of the continuous track is generally designed to protrude with grousers. This paper fundamentally studied the effect of grousers on the soil thrust of off-road tracked vehicles. Based on the soil-track interaction theory, a new soil thrust assessment method that properly takes into account the effect of grousers was developed. Also, the soil thrust of off-road tracked vehicles equipped with a number of grousers was evaluated using the developed assessment method. The results showed that grousers increased the soil thrust of the continuous track, enhancing the overall tractive performance of off-road tracked vehicles. These effects were more obvious as the height of grouser increased and the spacing of grouser decreased; thus, it is concluded that the grouser which has smaller shape ratio (span of the grouser to a grouser height) significantly enhances off-road tracked vehicle's performance.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.98-104
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• 2014

This study aims to predict the amount of soil loss from Mt. Palgong's small basin, by using influence factors derived from related models, including RUSLE and MUSLE models, and verify the validity of the model through a comparative analysis of the predicted values and measured values, and the results are as follows: The amount of soil loss were greatly affected by LS factor. In comparison with the measured value of the amount of total soil loss, the predicted values by the two models (RUSLE and MUSLE), appeared to be higher than those of the measured soil loss. Predicted values by RUSLE were closer to values of measured soil loss than those of MUSLE. However, coefficient of variation of MUSLE were lower, but two model's coefficient of variation in similar partial patterns in the prediction of soil loss. RUSLE and MUSLE, prediction soil loss models, proved to be appropriate for use in small mountainous basin. To improve accuracy of prediction of soil loss models, more effort should be directed to collect more data on rainfall-runoff interaction and continuous studies to find more detailed influence factors to be used in soil loss model such as RUSLE and MUSLE.