• 한국지구과학회지
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• 제35권1호
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• pp.69-87
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• 2014

이 논문에서는 구성 자료의 지구통계학적 시뮬레이션을 위해 다중 자료 변환 기반 조건부 시뮬레이션 틀을 제안하였다. 우선 일반적인 통계 기법의 적용이 가능하도록 구성 자료에 로그비 변환을 적용하였다. 다음 변환들로는 최소/최대 자기상관 인자 변환과 지시자 변환을 순차적으로 적용하였다. 독립적인 새로운 변수의 생성을 위해 최소/최대 자기상관 인자 변환을 적용하였으며, 적용 결과 개별 변수들의 독립적인 시뮬레이션이 가능해진다. 그리고 다중 가우시안 확률 모델을 따르지 않는 변수들의 비모수적 조건부 누적 확률 분포 모델링을 위해 지시자 변환을 적용하였다. 최종적으로는 적용한 변환 방법들의 역순으로 역 변환을 적용하였다. 간석지 표층 퇴적물 성분 자료를 대상으로 제안 시뮬레이션 기법의 적용 가능성을 예시하였다. 모든 시뮬레이션 결과들은 구성 자료의 제한 조건을 만족하면서 샘플 자료의 통계 특성을 잘 반영하였다. 구성 자료의 다수의 시뮬레이션 결과들을 이용한 표층 퇴적물 분류를 통해 기존 크리깅에서는 얻을 수 없는 분류 결과의 확률론적 평가가 가능하였다. 따라서 제안 시뮬레이션 틀은 다양한 구성 자료의 지구통계학적 시뮬레이션에 효과적으로 이용될 수 있을 것으로 기대된다.

• 한국재료학회지
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• 제19권2호
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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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• 제31권3호
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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.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -1
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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.

• 한국재료학회지
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• 제11권11호
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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.

• 한국정보과학회논문지:소프트웨어및응용
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• 제36권6호
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• pp.443-450
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• 2009

시스템 개발 초기 단계에 시스템의 기능적 요구사항이 제대로 반영되었는지를 검사하기 위해 시뮬레이션 기법을 이용한다. 일반적으로 시뮬레이션은 순차도에 나타난 추상적 시나리오를 바탕으로 상태머신을 직접 또는 랜덤으로 수행하는 행태로 진행된다. 시뮬레이션은 분석자가 직접 수행해야 하므로 많은 시간과 노력이 소요된다. 이 논문에서는 순차도 기반의 상태 머신의 시뮬레이션의 자동화 기법을 제공한다. 일반적으로 순차도와 상태머신의 추상화 레벨이 달라서 순차도에서 상세 시뮬레이션 트레이스를 추출하기가 쉽지 않다. 이 연구에서는 상태 머신을 LTS 모델로 변환하여 합성적 분석, 트랜지션 축약 등의 분석 방법을 적용하여 순차도와 동일한 추상화 레벨로 변환한 다음, 시나리오 포함여부를 검사한 후 해당 시나리오의 상세 시뮬레이션 트레이스를 생성한다. 이러한 시뮬레이션 트레이스는 순차도에 기술된 시나리오를 기반으로 시뮬레이션을 자동으로 수행할 뿐만 아니라, 특정 시스템 상태까지 자동 시뮬레이션할 수 있으므로 시뮬레이션을 효율적으로 진행할 수 있다.

• 자원리싸이클링
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• 제30권1호
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• pp.3-13
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• 2021

고급강은 소비자가 원하는 적절한 조성을 갖추고 있고 비금속 개재물의 제어를 통해 높은 청정도를 지닌 강을 의미하며, 철강 제품의 품질은 2차 정련 공정에서 제어하는 것이 지배적이다. 2차 정련에서는 시간이 흐름에 따라 용강, 슬래그, 비금속 개재물, 내화물 및 합금원소 간의 복잡한 반응이 동시에 일어나기 때문에 공정에 대한 제어가 쉽지 않다. 따라서 이전 연구자들은 2차 정련의 공정 예측을 위해 Kinetic 기반의 시뮬레이션 모델을 발표하였고, 정밀한 공정 예측을 위해 현재까지 발표된 시뮬레이션 모델들의 검토 및 분석이 필요하다. 본 연구에서는 Coupled Reaction 모델 기반의 2차 정련 모델들을 분석 및 검토하였고, 시뮬레이션 결과를 검토하였다.

• Advances in Energy Research
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• 제6권1호
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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.

• 복식
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• 제60권9호
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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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• 제8권2호
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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.