• Journal of the Korean earth science society
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• v.35 no.1
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• pp.69-87
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• 2014

This paper suggests a conditional simulation framework based on multiple data transformations for geostatistical simulation of compositional data. First, log-ratio transformation is applied to original compositional data in order to apply conventional statistical methodologies. As for the next transformations that follow, minimum/maximum autocorrelation factors (MAF) and indicator transformations are sequentially applied. MAF transformation is applied to generate independent new variables and as a result, an independent simulation of individual variables can be applied. Indicator transformation is also applied to non-parametric conditional cumulative distribution function modeling of variables that do not follow multi-Gaussian random function models. Finally, inverse transformations are applied in the reverse order of those transformations that are applied. A case study with surface sediment compositions in tidal flats is carried out to illustrate the applicability of the presented simulation framework. All simulation results satisfied the constraints of compositional data and reproduced well the statistical characteristics of the sample data. Through surface sediment classification based on multiple simulation results of compositions, the probabilistic evaluation of classification results was possible, an evaluation unavailable in a conventional kriging approach. Therefore, it is expected that the presented simulation framework can be effectively applied to geostatistical simulation of various compositional data.

• Korean Journal of Materials Research
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• v.19 no.2
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• pp.79-84
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• 2009

A series of experiments demonstrated that an addition of Ag into $(Cu_{0.5}Zr_{0.5})_{100-x}Ag_{x}$ amorphous alloys alters the plasticity of the alloys in a systematic manner. Energy dispersive x-ray spectroscopy (EDS) conducted on the $(Cu_{0.5}Zr_{0.5})_{100-x}Ag_{x}$ alloys exhibited the presence of compositional modulation, indicating that compositional separation had occurred. The presence of compositional modulation was also validated using a combined technique of molecular dynamics and Monte Carlo simulation. In this study, the effect of Ag on the compositional separation in $(Cu_{0.5}Zr_{0.5})_{100-x}Ag_{x}$ bulk amorphous alloys was investigated to understand the role played by the phase-separating element on the plasticity of the amorphous alloys.

• Communications for Statistical Applications and Methods
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• v.31 no.3
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• pp.349-363
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• 2024

Compositional data refers to data where the sum of the values of the components is a constant, hence the sample space is defined as a simplex making it impossible to apply statistical methods developed in the usual Euclidean vector space. A natural approach to overcome this restriction is to consider an appropriate transformation which moves the sample space onto the Euclidean space, and log-ratio typed transformations, such as the additive log-ratio (ALR), the centered log-ratio (CLR) and the isometric log-ratio (ILR) transformations, have been mostly conducted. However, in scenarios with sparsity, where certain components take on exact zero values, these log-ratio type transformations may not be effective. In this work, we mainly suggest an alternative transformation, that is the square-root transformation which moves the original sample space onto the directional space. We compare the square-root transformation with the log-ratio typed transformation by the simulation study and the real data example. In the real data example, we applied both types of transformations to the USG% data obtained from NBA, and used a density based clustering method, DBSCAN (density-based spatial clustering of applications with noise), to show the result.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.627-630
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• 2002

A methodology based on factorial design and Motto Carlo methods is developed and implemented for incorporating uncertainties within a multiphase subsurface flow and transport simulation system. Due to uncertainties in intrinsic permeability and longitudinal dispersivity, the predicted output is also uncertain based on the well-developed multiphase compositional simulator. The simulation results reveal that the uncertainties in input parameters pose considerable influences on the predicted output, and the mean and variance of permeability will have significant impacts on the modeling output. The proposed method offers an effective tool for evaluating uncertainty in multiphase flow simulation system.

• Korean Journal of Materials Research
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• v.11 no.11
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• pp.947-952
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• 2001

The meso-scale microstructure of the $Ni-Ni_3Al- Ni_3V$ system is crucial to obtain both high strength and high toughness. Its evolution may be predicted with the aid of computer simulation of the compositional separation for heat-treated alloys. In this study, computer simulations of the hypothetical A-B-C ternary system, which is similar to the $Ni-Ni_3Al- Ni_3V$ system in terms of phase equilibria, have been performed using the kinetic modeling. Simulated morphologies were changed with nominal compositions and model parameters. It was showed the current model was useful and the more realistic model was proposed.

• Journal of KIISE:Software and Applications
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• v.36 no.6
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• pp.443-450
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• 2009

In an earlier development phase, the simulation technique is one of the key analysis methods for checking the correctness of system's functional requirements. In general, simulation is manually or randomly performed by executing state machine diagrams according to the requirement scenarios. Therefore, simulation is one of the most effort-consuming tasks. In this paper, an automatic simulation technique of state machine diagrams is provided according to the scenarios of the sequence diagrams. It is not easy to generate detailed simulation traces from sequence diagrams due to different abstraction levels between sequence diagrams and state machine diagrams. In order to adjust for different abstraction levels, state machine diagrams and sequence diagrams are transformed into LTS models and compositional analysis and transition reduction are performed. After checking behavior conformance between them, detailed simulation traces for the state machine diagrams are generated. These simulation traces are used not only for performing automatic simulation but also for assisting analyzers to reach a specific system state in order to guide further efficient simulation.

• Resources Recycling
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• v.30 no.1
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• pp.3-13
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• 2021

In the secondary refining process for the production of high-grade steel, the proper composition is maintained by alloying elements, and non-metallic inclusions are controlled for high cleanliness. Complex reactions occur simultaneously between the molten steel, slag, inclusions, refractories, and alloying elements during the secondary refining process. Previous works have reported simulation models based on kinetics to predict the compositional changes in molten steel, slag, and inclusions in actual processes. Analytical reviews are required for the models to predict the process accurately. In this study, we reviewed and analyzed simulation models based on the coupled reaction model for the secondary refining process.

• Advances in Energy Research
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• v.6 no.1
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• pp.75-90
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• 2019

Anthropogenic greenhouse gas emissions are rising rapidly despite efforts to curb release of such gases. One long term potential solution to offset these destructive emissions is the capture and storage of carbon dioxide. Partially depleted hydrocarbon reservoirs are attractive targets for permanent carbon dioxide disposal due to proven storage capacity and seal integrity, existing infrastructure. Optimum well completion design in depleted reservoirs requires understanding of prominent geomechanics issues with regard to rock-fluid interaction effects. Geomechanics plays a crucial role in the selection, design and operation of a storage facility and can improve the engineering performance, maintain safety and minimize environmental impact. In this paper, an integrated geomechanics workflow to evaluate reservoir caprock integrity is presented. This method integrates a reservoir simulation that typically computes variation in the reservoir pressure and temperature with geomechanical simulation which calculates variation in stresses. Coupling between these simulation modules is performed iteratively which in each simulation cycle, time dependent reservoir pressure and temperature obtained from three dimensional compositional reservoir models in ECLIPSE were transferred into finite element reservoir geomechanical models in ABAQUS and new porosity and permeability are obtained using volumetric strains for the next analysis step. Finally, efficiency of this approach is demonstrated through a case study of oil production and subsequent carbon storage in an oil reservoir. The methodology and overall workflow presented in this paper are expected to assist engineers with geomechanical assessments for reservoir optimum production and gas injection design for both natural gas and carbon dioxide storage in depleted reservoirs.

• Journal of the Korean Society of Costume
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• v.60 no.9
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• pp.16-25
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• 2010

This study reinterpreted the formative design elements of traditional grate patterns to create new lattice patterns and come up with a design concept for fashion-cultural products that highlight the uniqueness of traditional Korean culture and its characteristic features. Methodologically, the computer design software programs Adobe Illustrator CS2 and Adobe Photoshop were used to make grate patterns motifs. and they were applied to scarves and again to blouses using a three-dimensional simulation technique. In this study, three basic motifs for a new formative image were set using graphical functions such as omitting, simplifying, overlapping, repeating and reducing shapes based on the images of traditional 亞-shaped, arched and floral lattices, and each motif was expanded to have two variations with different colors applied to them. The direction of basic motif design was set to fit for each of fashion-cultural items such as scarves and blouses. Basic colors for motifs were arranged to create a colorful and modern but staid image in pink, blue, purple, green, yellow and brown tones. Based on a developed motif, changes were made in blouse design with lattice patterns through a variety of effects such as repetition, rotation, cross-arrangement, and oblique arrangement, and three-dimensional simulation was used to bring the design to life. Scarf design employed and applied the existing motifs in an appropriate manner for design purposes and reconstructed them through such effects as repetition, rotation, compositional variation and gradation to express a gorgeous and refined image.

• Coupled systems mechanics
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• v.8 no.2
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• pp.129-146
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• 2019

The main goal of this work is to develop a numerical simulator to study an isothermal single-phase two-component flow in a naturally fractured oil reservoir, taking into account advection and diffusion effects. We use the Peng-Robinson equation of state with a volume translation to evaluate the properties of the components, and the discretization of the governing partial differential equations is carried out using the Finite Difference Method, along with implicit and first-order upwind schemes. This process leads to a coupled non-linear algebraic system for the unknowns pressure and molar fractions. After a linearization and the use of an operator splitting, the Conjugate Gradient and Bi-conjugated Gradient Stabilized methods are then used to solve two algebraic subsystems, one for the pressure and another for the molar fraction. We studied the effects of fractures in both the flow field and mass transport, as well as in computing time, and the results show that the fractures affect, as expected, the flow creating a thin preferential path for the mass transport.