• Geotechnical Engineering
• /
• v.3 no.4
• /
• pp.41-54
• /
• 1987

A stochastic numerical analysis for predicting the groundswater fluctuations in hillside slopes is performed in this paper to account for the uncertainties associated with the rainfall and site characteristics. The effect of spatial variabilities of aquifer parameters and the effect of temporal variability of recharge on the groundwater fluctuations are studied in depth. The Kriging is used to account for the spatial tariabilities of aquifer parameters. This technique prolevides the best linear unbiased estimator of a parameter and its minimum variance from a litsitem number of measured data. A stochastic one-dimensional numerical model is delreloped b) combining the groundwater flow model, the Kriging, and the first-order second-moment analysis. In addition, a two dimensional detelministic groundwater model is developed to study the change of ground water surfas in the transverse direction as well as in the downslope direction. It is revealed that the undulations of the impervious bedrock in addition to the permeability and the specific yield have an important influence on the fluctuations of the groundwater surface. It is also found that th'e groundwater changes significantly in the transverse direction as well as in the downslope direction. The results obtained in this analysis may be used for evaluation of landslide risks due to high porewater pressure.

• Journal of the Korean Chemical Society
• /
• v.53 no.6
• /
• pp.653-662
• /
• 2009

Developing effective tools for predicting absorption, distribution, metabolism, excretion properties and toxicity (ADME/T) of new chemical entities in the early stage of drug design is one of the most important tasks in drug discovery and development today. As one of these attempts, support vector machines (SVM) has recently been exploited for the prediction of ADME/T related properties. However, two problems in SVM modeling, i.e. feature selection and parameters setting, are still far from solved. The two problems have been shown to be crucial to the efficiency and accuracy of SVM classification. In particular, the feature selection and optimal SVM parameters setting influence each other, which indicates that they should be dealt with simultaneously. In this account, we present an integrated practical solution, in which genetic-based algorithm (GA) is used for feature selection and grid search (GS) method for parameters optimization. hERG ion-channel inhibitor classification models of ADME/T related properties has been built for assessing and testing the proposed GA-GS-SVM. We generated 6 different models that are 3 different single models and 3 different ensemble models using training set - 1891 compounds and validated with external test set - 175 compounds. We compared single model with ensemble model to solve data imbalance problems. It was able to improve accuracy of prediction to use ensemble model.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.14 no.5
• /
• pp.65-76
• /
• 2010

In this paper, earthquake fragility analysis has been comparatively performed with regard to a buried gas pipeline of API X65 which has been widely used in Korea. For this purpose, a nonlinear time-history analyses has been carried out for 15 different analytical models of a buried gas pipeline in terms of the selected 12 sets of earthquake ground motions with 0.1g of scaling interval. Following that, earthquake fragility analyses have been conducted using the maximum axial strain of the pipeline obtained from the nonlinear time-history analyses. Parameters under consideration for subsequent earthquake fragility analyses are soil conditions, end-restraint conditions, burial depth and the type of pipeline. Comparative analyses reveal that whereas the first three parameters influence the fragility curves, particularly soil conditions amongst the three parameters, the last parameter has a little effect on the curves. In all, the present study can be considered as a benchmark fragility analysis of a buried gas pipeline in the absence of an earthquake fragility analysis of the pipeline and thus is expected to be a useful source regarding earthquake fragility analyses of a buried gas pipelines.

• Computers and Concrete
• /
• v.3 no.5
• /
• pp.301-312
• /
• 2006

Experimental research revealed that the spatial dispersion of aggregate grains exerts pronounced influences on the mechanical and durability properties of concrete. Therefore, insight into this phenomenon is of paramount importance. Experimental approaches do not provide direct access to three-dimensional spacing information in concrete, however. Contrarily, simulation approaches are mostly deficient in generating packing systems of aggregate grains with sufficient density. This paper therefore employs a dynamic simulation system (with the acronym SPACE), allowing the generation of dense random packing of grains, representative for concrete aggregates. This paper studies by means of SPACE packing structures of aggregates with a Fuller type of size distribution, generally accepted as a suitable approximation for actual aggregate systems. Mean free spacing $\bar{\lambda}$, mean nearest neighbour distance (NND) between grain centres $\bar{\Delta}_3$, and the probability density function of ${\Delta}_3$ are used to characterize the spatial dispersion of aggregate grains in model concretes. Influences on these spacing parameters are studied of volume fraction and the size range of aggregate grains. The values of these descriptors are estimated by means of stereological tools, whereupon the calculation results are compared with measurements. The simulation results indicate that the size range of aggregate grains has a more pronounced influence on the spacing parameters than exerted by the volume fraction of aggregate. At relatively high volume density of aggregates, as met in the present cases, theoretical and experimental values are found quite similar. The mean free spacing is known to be independent of the actual dispersion characteristics (Underwood 1968); it is a structural parameter governed by material composition. Moreover, scatter of the mean free spacing among the serial sections of the model concrete in the simulation study is relatively small, demonstrating the sample size to be representative for composition homogeneity of aggregate grains. The distribution of ${\Delta}_3$ observed in this study is markedly skew, indicating a concentration of relatively small values of ${\Delta}_3$. The estimate of the size of the representative volume element (RVE) for configuration homogeneity based on NND exceeds by one order of magnitude the estimate for structure-insensitive properties. This is in accordance with predictions of Brown (1965) for composition and configuration homogeneity (corresponding to structure-insensitive and structure-sensitive properties) of conglomerates.

• Journal of Convergence Society for SMB
• /
• v.3 no.2
• /
• pp.27-32
• /
• 2013

Wireless Body Area Networks (WBAN) have been made possible by the emergence of small and lightweight wireless systems such as Bluetooth, enabled devices and PDAs. Antennas are an essential part of any WBAN system and due to various technical requirements and physical constraints, careful consideration of their design and deployment is needed. This paper is proposing on the design of wearable antenna as parts of clothing to serve communications functions, such as tracking and navigation in health care applications. The substrates of the wearable antennas will be made from textile materials and since it is wearable, it should have a small size, be light weight, low maintenance, and unobtrusive. This proposed paper will also investigate the influence of different parameters for wearable antenna including types of textile/substrate to ensure that the antenna design satisfies WBAN requirements. The characteristics and behavior of the antenna need to adhere to specifications set by wireless standards and system technology requirements. This means that the transmitting and receiving frequency bands of the various units need to be chosen accordingly. Since there are restrictions on the level of power to which the human body can be exposed to, the antenna as well as other RF system components must be designed to meet these restrictions. Antenna gain, which directly affects power transmitted, is a critical parameter in ensuring power levels fall within the safety guidelines and so will be of primary importance in the design. The electromagnetic interaction between WBAN antennas and devices and the human body will also be explored.

• Korean Journal of Materials Research
• /
• v.8 no.10
• /
• pp.925-930
• /
• 1998

EPMA and XPS on $Bi_2Sr_2-\chi_LCa_1+\chi_LCu_2O_{8+d}$($\chi_L$ = 0.01, 0.2, 0.3, 0.4, 0.5, 0.6) films by LPE method were performed in order to investigate Sr and Ca distributions in SrO- and Ca-layers. It is found that $T_C^{zero}$ carrier concentration and lattice parameter c monotonically decreases with increasing $\chi_L$. Sr and Ca contents in Ca-layer change in proportion to that in melt. On the other hand, in SrO-layer, Ca content strongly depends on Sr content in that layer and not on Ca content in melt. Since deficiency in SrO-layer increases and $T_C^{zero}$ creases with $\chi_L$,t is found that the deficiencies of Sr and Ca atoms in the SrO-layer has a influence on reducing $T_C^{zero}$.

• Earthquakes and Structures
• /
• v.13 no.1
• /
• pp.59-66
• /
• 2017

Modern seismic codes rely on performance-based seismic design methodology which requires that the structures withstand inelastic deformation. Many studies have focused on the inelastic deformation ratio evaluation (ratio between the inelastic and elastic maximum lateral displacement demands) for various inelastic spectra. This paper investigates the inelastic response spectra through the ductility demand ${\mu}$, the yield strength reduction factor $R_y$, and the inelastic deformation ratio. They depend on the vibration period T, the post-to-preyield stiffness ratio ${\alpha}$, the peak ground acceleration (PGA), and the normalized yield strength coefficient ${\eta}$ (ratio of yield strength coefficient divided by the PGA). A new inelastic deformation ratio $C_{\eta}$ is defined; it is related to the capacity curve (pushover curve) through the coefficient (${\eta}$) and the ratio (${\alpha}$) that are used as control parameters. A set of 140 real ground motions is selected. The structures are bilinear inelastic single degree of freedom systems (SDOF). The sensitivity of the resulting inelastic deformation ratio mean values is discussed for different levels of normalized yield strength coefficient. The influence of vibration period T, post-to-preyield stiffness ratio ${\alpha}$, normalized yield strength coefficient ${\eta}$, earthquake magnitude, ruptures distance (i.e., to fault rupture) and site conditions is also investigated. A regression analysis leads to simplified expressions of this inelastic deformation ratio. These simplified equations estimate the inelastic deformation ratio for structures, which is a key parameter for design or evaluation. The results show that, for a given level of normalized yield strength coefficient, these inelastic displacement ratios become non sensitive to none of the rupture distance, the earthquake magnitude or the site class. Furthermore, they show that the post-to-preyield stiffness has a negligible effect on the inelastic deformation ratio if the normalized yield strength coefficient is greater than unity.

• Journal of Embryo Transfer
• /
• v.29 no.3
• /
• pp.289-296
• /
• 2014

The pedigree information and race records of 1,000 m finishing time of Jeju race horses at KRA were used to study the effect of amount of pedigree information and parental misidentification on the estimates of genetic parameters. The modified data sets were made at the range of 2.5 to 25% parental misidentifications or loss of parental information of individuals with an increment of 2.5 percent. For each incremental level, 20 randomly replicated data sets were obtained and analyzed by single-trait analysis with a DF-REML(AI) algorithm. As the rate of misidentification increased or the amount of pedigree information decreased, the estimates of fraction of additive genetics variance component gradually decreased almost linearly (p<0.05), while the estimated fractions of error variance and permanent environmental variance components gradually increased for the finishing time. Regression coefficients of the percentage amount of both parents' information loss and incorrect pedigree information on additive genetic variances were -0.079 and -0.114, respectively (p<0.01). The estimate of heritability decreased by 0.92% for one percent loss of both parents' information and 1.39% for one percent increase of both parental misidentifications of progeny (p<0.01). For the consideration of probable incorrect and missing parent information of progeny in this early population of Jeju horses, the estimates of additive genetic parameters would be biased downward about ten percent. This results indicate that the amount of pedigree information loss and misidentification of progeny would severely affect estimates of genetic parameters and would reduce genetic gains for selection in Jeju horse population.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.48 no.1
• /
• pp.23-33
• /
• 2020

In this study, the effect of surface roughness distribution and its influence on the inflight icing code was investigated. Previous numerical studies focused on the magnitude of surface roughness, and the effects were only addressed in terms of changes in thermal boundary layers with fully turbulent assumption. In addition, the empirical formula was used to take account the turbulent transition due to surface roughness, which was regarded as reducing the accuracy of ice shape prediction. Therefore, in this study, the turbulent transition model based on the two-equation turbulence model was applied to consider the effects of surface roughness. In order to consider the effect of surface roughness, the transport equation for roughness amplification parameter was applied, and the surface roughness distribution model was implemented to consider the physical properties. For validation, the surface roughness, convective heat transfer coefficient, and ice shape were compared with experimental results and other numerical methodology. As a result, it was confirmed that the excessive prediction of the heat transfer coefficient at the leading edge and the ice horn shape at the bottom of the airfoil were improved accordingly.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.11 no.3
• /
• pp.193-198
• /
• 2013

In general, boron recovery of 40-90% could be achieved by Reverse Osmosis (RO) membranes in neutral pH condition. As an emerging technology, Forward Osmosis (FO) membrane has attracted growing interest in wastewater treatment and desalination. The objective of this study is to evaluate the possibility of the boron removal in radioactive liquid waste by FO. In this study, the performance of FO was investigated to remove boron in the simulated liquid waste as the factors such as pH, osmotic pressure, ionic strength of solution, etc. The pH of feed solution is a major operating parameter which strongly influences to the permeation of boron and more than 80% of boron content can be separated when conducted at pH values less than 7. The water flux is not influenced but the boron flux and permeation rate tends to decrease in the low salt concentration of 1,000 mg/L. The boron flux increases linearly, but the permeation ratio of reducing boron is nearly constant even with changes in the draw solution concentration.