• Tunnel and Underground Space
• /
• v.14 no.2
• /
• pp.142-153
• /
• 2004

To investigate the influence of the rock mass inhomogeneity caused by layer geometry on the regional stress distribution the cuboid models considering a homogenous rock mass, inhomogeneous rock mass with plane layers and with uneven layers were analyzed and discussed. It was confirmed that the structure and existence of layers in rock mass affected the regional stress distribution. An approach based on an inverse analysis of the measured local stresses and the 3D finite element analysis was suggested, and used to estimate the regional stress field of the homogeneous and inhomogeneous models, which consist of the surface geometry of ground and both the surface and layer geometry respectively. Additionally, the approach of the regional stress considering the layer geometry in the rock mass was verified to estimate the regional stress field for a site.

• The Journal of Korean Society for Radiation Therapy
• /
• v.18 no.2
• /
• pp.75-80
• /
• 2006

Purpose: In radiation therapy, precise calculation of dose toward malignant tumors or normal tissue would be a critical factor in determining whether the treatment would be successful. The Radiation Treatment Planning (RTP) system is one of most effective methods to make it effective to the correction of dose due to CT number through converting linear attenuation coefficient to density of the inhomogeneous tissue by means of CT based reconstruction. Materials and Methods: In this study, we carried out the measurement of CT number and calculation of mass density by using RTP system and the homemade inhomogeneous tissue Phantom and the values were obtained with reference to water. Moreover, we intended to investigate the effectiveness and accuracy for the correction of inhomogeneous tissue by the CT number through comparing the measured dose (nC) and calculated dose (Percentage Depth Dose, PDD) used CT image during radiation exposure with RTP. Results: The difference in mass density between the calculated tissue equivalent material and the true value was ranged from $0.005g/cm^3\;to\;0.069g/cm^3$. A relative error between PDD of RTP and calculated dose obtained by radiation therapy of machine ranged from -2.8 to +1.06%(effective range within 3%). Conclusion: In conclusion, we confirmed the effectiveness of correction for the inhomogeneous tissues through CT images. These results would be one of good information on the basic outline of Quality Assurance (QA) in RTP system.

• Journal of Soil and Groundwater Environment
• /
• v.11 no.5
• /
• pp.1-8
• /
• 2006

The objective of this study is to assess impacts of sorption heterogeneity on the transport of leachate leaked from unlined landfill sites and is accomplished by examining the results from a series of Monte-Carlo simulations. For random distribution coefficient ($K_{d}$) fields with four different levels of heterogeneity ranging from homogeneous to highly heterogeneous, the transport of leachate was investigated by linking a saturated flow model with a contaminant transport model. Impacts of a chemical heterogeneity were evaluated using point statistics values such as mean, standard deviation, and coefficient of variation of the concentration obtained at monitoring wells from 100 Monte-Carlo trials. Inspection of point statistics shows that the distribution of distribution coefficient in the landfill site proves to be an important parameter in controlling leachate concentrations. In comparison to homogeneous sorption, heterogeneous $K_{d^-}$ fields produce the variability in the leachate concentration for different realizations. The variability increases significantly as the variance in the $K_{d^-}$ field and the travel time between source and monitoring well increase. These outcomes indicate that use of a constant homogeneous $K_{d}$ value for predicting the transport of leachate can result in significant error, especially when variability in $K_{d}$ is high.

• Tunnel and Underground Space
• /
• v.13 no.2
• /
• pp.117-124
• /
• 2003

The fracture processes under static tensile loading were simulated using a proposed numerical simulation method, based on finite element method and fracture mechanism, and analyzed to verify an influence of rock inhomogeneity on static tensile strength. Static tensile strengths for the specimen models with different spatial microscopic tensile strength when m=5 and m=50 were estimated. These analyses revealed that the static tensile strength becomes closer to the mean microscopic tensile strength at a higher uniformity coefficient and the scatter of the strength data decreases in increasing the uniformity coefficients. Therefore, it could be concluded that rock inhomogeneity has an effect on static tensile strength.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.24 no.4
• /
• pp.341-353
• /
• 2022

Pipelines are buried in urban area, and the position (depth and orientation) of buried pipeline should be clearly identified before ground excavation. Although various geophysical methods can be used to detect the buried pipeline, it is not easy to identify the exact information of pipeline due to heterogeneous ground condition. Among various non-destructive geo-exploration methods, ground penetration radar (GPR) can explore the ground subsurface rapidly with relatively low cost compared to other exploration methods. However, the exploration data obtained from GPR requires considerable experiences because interpretation is not intuitive. Recently, researches on automated detection technology for GPR data using deep learning have been conducted. However, the lack of GPR data which is essential for training makes it difficult to build up the reliable detection model. To overcome this problem, we conducted a preliminary study to improve the performance of the detection model using finite difference time domain (FDTD)-based numerical analysis. Firstly, numerical analysis was performed with homogeneous soil media having single permittivity. In case of heterogeneous ground, numerical analysis was performed considering the ground heterogeneity using fractal technique. Secondly, deep learning was carried out using convolutional neural network. Detection Model-A is trained with data set obtained from homogeneous ground. And, detection Model-B is trained with data set obtained from homogeneous ground and heterogeneous ground. As a result, it is found that the detection Model-B which is trained including heterogeneous ground shows better performance than detection Model-A. It indicates the ground heterogeneity should be considered to increase the performance of automated detection model for GPR exploration.

• Economic and Environmental Geology
• /
• v.44 no.2
• /
• pp.161-170
• /
• 2011

The multiphase flow simulator, CHEMPS, was developed based on the fractional flow approach reported in the petroleum engineering literature considering fully three phase flow in physically and chemically heterogeneous media. It is a extension of MPS developed by Suk and Yeh (2008) to include the effect of wettability on the migration of NAPL. The fractional flow approach employs water, total liquid saturation and total pressure as the primary variables. Most existing models are limited to two-phase flow and specific boundary conditions when considering physically heterogeneous media. In addition, these models focused mainly on the water-wet media. However, in a real system, variations in wettability between water-wet and oil-wet media often occur. Furthermore, the wetting of porous media by oil can be heterogeneous, or fractional, rather than uniform due to the heterogeneous nature of the subsurface media and the factors that affect the wettability. Therefore, in this study, the chemically heterogeneous media considering fractional wettability as well as physically heterogeneous media were simulated using CHEMPS. In addition, the general boundary conditions were considered to be a combination of two types of boundaries of individual phases, flux-type and Dirichlet type boundaries.

• Polymer(Korea)
• /
• v.30 no.6
• /
• pp.486-491
• /
• 2006

Heterogeneous membranes were prepared by compression molding for the recovery of ammonium ion from waste water. Degree of sulfonation for sulfonated ion exchange resin increased with increasing amount of chlorosulfonic acid. It was 3.32 meq/g at 10 vol%. The tensile strength and elongation of the heterogeneous membrane was decreased with increasing contents of ion exchange resin. The tensile strength for LLDPE matrix membrane was the highest and also the elongation for EVA matrix membranes were the highest. The water content of heterogeneous membrane was increased with increasing contents of ion exchange resin. The maximum value of transport number for PE matrix membrane was 0.973. The electrical resistance of LLDPE matrix membrane was the lowest. It was value of $10.36{\Omega}/cm^2$ at 70 wt% resins.

• Proceedings of the KSEEG Conference
• /
• 2005.04a
• /
• pp.238-241
• /
• 2005

• Journal of the Korean Geophysical Society
• /
• v.5 no.4
• /
• pp.337-344
• /
• 2002

The alluvial deposits along meandering rivers can be used as an artificial aquifer for infiltration of river waters. Internal heterogeneity of the alluvial deposits is a prerequisite information for the development of alluvial groundwater because vortical and lateral movement of alluvial ground water depends on the internal heterogeneity The internal heterogeneity due to variations in channel behavior can be delineated using GPR survey, GPR profiles for the point bar deposits near Buyeo county reveals two different stratigraphic units: the lower inclined heterogeneous strata and the upper horizontally stratified strata. The upper unit is largely indicative of vertical accumulation by overbank floods within a floodplain, whereas the lower one represents typical point bar deposits formed by lateral accretion. The stratigraphic variation in the heterogeneity shows that GPR survey is a useful and necessary investigation method for the development of alluvial ground water.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.19 no.1
• /
• pp.94-106
• /
• 1990

사람들이나 동물의 소화관의 상재균으로서 중요한 Lactobacillus acidophilus의 여러균주를 사용하여 세포표면의 성상을 조사하였다. 불리한 세포벽의 negative 염색한 표본을 전자현미경으로 검토한 결과 사용한 21주중 15주는 세포벽외층에 단백질로 구성딘 regular array를 생산하고 있음을 알았다. RA를 구성하는 단백질의 분자량은 41KDa-48KDa이었다 아미노사노성 및 Staphylococcus au-reus V8 protease로 한정분해 후 및 N-chlorosuccini-mide로 부분절단후의 peptide map에서 Johnson등의 분류의 subgroup A-1에 속하는 균주가 생산하는 RA단백질은 불균질하였으나 그외 균주의 RA단백질은 같은 subgroup에 속하고 있어도 불균질하였음을 알았다 따라서 RA단백질은 불균질하였으나 그외 균주의 RA단백질은 같은 subgroup에 속하고 있어도 불균질하였음을 알았다 따라서 RA생산의 유무 및 RA단백질의 분자량측정과 peptide mapping을 행하면 지금까지 행해온 DNA-hybridization과 같은 복잡한 절차를 사용하지 않아도 subgroup A-1의 L. acidophilus가 동정 가능함을 알았다 L acidophilus의 세포표면소수성은 일반적으로 RA를 생산하지 않는 균주보다는 RA를 생사하는 균주에 높은 것이많았다 RA생산균주에 있어서는 RA단백질은 세포표면소수성과 직접관계하고 있는 것은 적었다.