• Journal of Environmental Science International
• /
• v.22 no.4
• /
• pp.415-424
• /
• 2013

In this paper, time series of soil moisture were measured for a steep forest hillslope to model and understand distinct hydrological behaviours along two different transects. The transfer function analysis was presented to characterize temporal response patterns of soil moisture for rainfall events. The rainfall is a main driver of soil moisture variation, and its stochastic characteristic was properly treated prior to the transfer function delineation between rainfall and soil moisture measurements. Using field measurements for two transects during the rainy season in 2007 obtained from the Bumrunsa hillslope located in the Sulmachun watershed, a systematic transfer functional modeling was performed to configure the relationships between rainfall and soil moisture responses. The analysis indicated the spatial variation pattern of hillslope hydrological processes, which can be explained by the relative contribution of vertical, lateral and return flows and the impact of transect topography.

• Korean Journal of Agricultural Science
• /
• v.33 no.1
• /
• pp.85-95
• /
• 2006

A model experiment has been performed to get the heat transfer coefficient on the soil surface in the closed ecosystem. The heat flux on the soil surface was measured and the heat transfer coefficient was derived in the following two cases with 5-stepped control of inside air current speed. One case was that heat flowed from air to soil and the other case was that heat flowed from soil to air. Three dimensional CFD model has been set to simulate thermal environment in the closed ecosystem including soil layers. The standard $k-{\varepsilon}$ model of the CFD program was chosen for turbulence model and heating wire buried in the soil layers was set as heat source option to simulate the case when the temperature of soil surface was higher than that of inside air in the closed ecosystem. Between one case that heat flowed from air to soil and the other case that heat flowed from soil to air, there were big differences in the temperature distribution of soil layers and the heat transfer coefficient of the soil surface. The increasing rate of heat transfer coefficient on each case according to the increase of inside air current speed was similar to each other and it respectively increased linearly. But the heat transfer coefficient on the case that heat flowed from soil to air was much bigger than that of the other case. The model was validated by comparing simulated values of CFD model with measured values of the model experiment. Simulated and measured temperature of inside air and soil layers, and heat transfer coefficient of the soil surface were well accorded and the range of corrected $R^2$ was 0.664 to 0.875. The developed CFD model was well simulated in parts of the temperature of inside air and soil layers, the distribution of the inside air current speed, and heat transfer coefficient of the soil surface were able to be quantitatively analyzed by using this model. Therefore, the model would be applied and used for analysis of heat transfer coefficient between air and surface in various agricultural facilities.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2000.11a
• /
• pp.171-176
• /
• 2000

Bioremediation of hazardous hydrophobic organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), is a major environmental concern due to their toxic and carcinogenic properties. Due to their hydrophobicity, the hydrophobic organic compounds are mainly associated with the soil organic matter or nonaqueous-phase liquids. A major question concerns the relationships between biodegradation and sorption. This work develops and utilizes a non- steady state model for evaluating the interactions between sorption and biodegradation of phenanthrene, a 3-ring PAH compound, in soil-slurry systems. The model includes sorption/desorption of a target compound, its utilization by microorganisms as a primary substrate existing in the dissolved phase and/or the sorbed phase in biomass and soil, oxygen transfer, and oxygen utilization as an electron acceptor. Biodegradation tests with phenanthrene were conducted in liquid and soil-slurry systems. The soil-slurry tests were performed with very different mass transfer rate: fast mass transfer in a flask test at 150 rpm, and slow mass transfer in a roller-bottle test at 2 rpm. In the slurry tests, phenanthrene was degraded more rapidly than in liquid tests, but with a similar rate in both slurry systems. Modeling analyses with several hypotheses indicate that a model without biodegradation of compound sorbed to the soil was not able to account for the rapid degradation of phenanthrene, particularly in the roller bottle slurry test. Reduced mass-transfer resistance to bacteria attached to the soil is the most likely phenomenon accounting for rapid sorbed-phase biodegradation.

• Smart Structures and Systems
• /
• v.30 no.1
• /
• pp.63-74
• /
• 2022

The deformation coordination between a rock/soil mass and an optical sensing cable is an important issue for accurate deformation monitoring. A stress-controlled triaxial apparatus was retrofitted by introducing an optical fiber into the soil specimen. High spatial resolution optical frequency domain reflectometry (OFDR) was used for monitoring the strain distribution along the axial direction of the specimen. The results were compared with those measured by a displacement meter. The strain measured by the optical sensing cable has a good linear relationship with the strain calculated by the displacement meter for different confining pressures, which indicates that distributed optical fiber sensing technology is feasible for soil deformation monitoring. The performance of deformation coordination between the sensing cable and the soil during unloading is higher than that during loading based on the strain transfer coefficients. Three hypothetical strain distributions of the triaxial specimen are proposed, based on which theoretical models of the strain transfer coefficients are established. It appears that the parabolic distribution of specimen strain should be more reasonable by comparison. Nevertheless, the strain transfer coefficients obtained by the theoretical models are higher than the measured coefficients. On this basis, a strain transfer model considering slippage at the interface of the sensing cable and the soil is discussed.

• Journal of Biosystems Engineering
• /
• v.21 no.4
• /
• pp.449-455
• /
• 1996

The temperature distributions at various soil depths were predicted by heat transfer model during and after infrared irradiation on sand loam or loam soil. At each soil depth, predicted and measured temperature distributions were compared with using the mean relative percentage deviation and standard error. The mean relative percentage deviation was less than 10% between predicted and measured temperature distributions at each soil depth. Thus, it was concluded that the temperature distribution at each soil depth could be predicted satisfactorily by heat transfer model. Also, it is expected that these predicted temperature distributions can be used as basic information for determining the working speed of weeder and the size when the real weeder is constructed.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2000.03b
• /
• pp.151-158
• /
• 2000

The lateral deformation of one row pile groups was investigated based on analytical study and a numerical analysis. The emphasis was on quantifing the load transfer of pile groups subjected to lateral soil movement. An analytical method to consider pile-soil interaction in weathered soil was developed using load-transfer curve methods. Through the comparative study, it is found that the prediction by present approach is in good agreement with the general trend observed by in-situ measurements.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2002.09a
• /
• pp.203-206
• /
• 2002

토양 오염의 주된 원인인 디젤은 휘발성과 용해도가 낮아 생물학적 처리법이 많이 이용된다. 생물학적 처리에서 Bioavailability 는 생분해의 속도에 영향을 미치며 유효성평가에 있어 중요하다. 디젤로 오염된 토양의 생분해 특성 및 Bioavailability를 평가하기 위하여 생분해 실험과 mass transfer 실험을 수행하였다. 생분해 속도와 mass transfer 속도의 비교를 통해 생분해 초기에는 mass transfer에 의해 그 속도가 부분적으로 제한을 받으나, 일정시간 후에는 mass transfer 속도에 의해 생분해 속도가 결정되어짐을 알 수 있었다. Multi -component 인 디젤 성분에서의 mass transfer 의 영향을 알기 위해 각 성분별에 따라 조사한 결과, linear H.C 성분과 고 휘발성 성분은 생분해 속도가 초기에는 mass transfer 에 의해 부분적으로 제한되고 후에 mass transfer 에 의해 결정되어지나, tracked H.C 성분과 저휘발성 성분은 전체적으로 mass transfer 에 의해 생분해 속도가 제한되고 있음을 알 수 있었다.

• Structural Engineering and Mechanics
• /
• v.20 no.5
• /
• pp.575-587
• /
• 2005

Using the nonlinear load transfer function for pile side soil and the linear load transfer function for pile end soil, a combined approach of the incremental load transfer matrix method and the approximate differential equation solution method is presented for the nonlinear analysis of interaction between flexible pile group and soil. The proposed method provides an effective approach for the solution of the nonlinear interaction between flexible pile group under rigid platform and surrounding soil. To verify the accuracy of the proposed method, a static load test for a nine-pile group under a rigid platform is carried out. The finite element analysis is also conducted for comparison purposes. It is found that the results from the proposed method match very well with those from the experimental test and are better in comparison with the finite element method.

• The Korean Journal of Ecology
• /
• v.17 no.2
• /
• pp.223-235
• /
• 1994

The transfer of plasmid-borne genes coding for resistance to antibiotics (Ampicillin, Carbenicillin, and tetracycline) among 16 strains isolated from Mankyong River was examined. The survival of donors, recipient, and transformants in sterile and nonsterile soil (the soil was amended with 12% vol/vol with the clay mineral, montmorillonite) was also studied. In sterile soil, the survival was prolonged in the order of donors, transformants, and recipient. The survival of donors, transformants, and recipient increased when the soil was amended with 12% montmorillonite, but not in nonsterile soil. In nonsterile soil, donors survived longer than transformants and recipient, but the survival of transformants and recipient showed no significant differences. The results of these studies suggest that genes can be transferred by transformation, and transferred genes can survive in soil for a considerable time.

• Nuclear Engineering and Technology
• /
• v.53 no.3
• /
• pp.960-966
• /
• 2021

A technical approach to design and carry out an experiment to determine the uptake of selected radionuclides in site-specific conditions in Kuwait was developed and successfully executed for developing a radioecological decision support system. The radionuclides from soil-to-plant transfer factors have been obtained for leafy and non-leafy vegetables, and root crops cultivated in Kuwait. Two types of vegetated soils were selected and spiked with high concentrations of three relatively short-lived selected radionuclides (⁸⁵Sr, ¹³⁴Cs, and ¹³³Ba). The highest strontium and barium transfer factors were found in the order: leafy vegetables > root crops > non-leafy vegetables. The approximate range of radiocesium transfer factor was found to be low in all plant groups and was comparable to those reported elsewhere in different soil types of temperate and tropical environments. A strong negative correlation between the obtained transfer factors and the distribution coefficient of the radionuclide in soil was found. It is recommended to adopt the newly derived parameters for the sensitive areas in Kuwait and other Gulf countries instead of using the generic parameters, whenever dose calculation codes are used. This will help to more accurately assess and predict the end results of the committed effective dose equivalent through ingestion pathway.