• 한국세라믹학회지
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• 제53권3호
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• pp.263-272
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• 2016

Electronic structure calculations have become a powerful foundation for computational materials engineering. Four major factors have enabled this unprecedented evolution, namely (i) the development of density functional theory (DFT), (ii) the creation of highly efficient computer programs to solve the Kohn-Sham equations, (iii) the integration of these programs into productivity-oriented computational environments, and (iv) the phenomenal increase of computing power. In this context, we describe recent applications of the Vienna Ab-initio Simulation Package (VASP) within the MedeA$^{(R)}$ computational environment, which provides interoperability with a comprehensive range of modeling and simulation tools. The focus is on technological applications including microelectronic materials, Li-ion batteries, high-performance ceramics, silicon carbide, and Zr alloys for nuclear power generation. A discussion of current trends including high-throughput calculations concludes this article.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1061-1064
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• 2004

Molecular visualization software has the common objective of manipulation and interpretation of data from numerical simulations. They visualize many complicated molecular structures with personal computer and workstation, to help analyze a large quantity of data produced by various computational methods. However, users are often discouraged from using these tools for visualization and analysis due to the difficult and complicated user interface. In this regard, we have developed an easy-to-use three-dimensional molecular visualization and analysis program named POSMOL. This has been developed on the Microsoft Windows platform for the easy and convenient user environment, as a compact program which reads outputs from various computational chemistry software without editing or changing data. The program animates vibration modes which are needed for locating minima and transition states in computational chemistry, draws two and three dimensional (2D and 3D) views of molecular orbitals (including their atomic orbital components and these partial sums) together with molecular systems, measures various geometrical parameters, and edits molecules and molecular structures.

• 한국정밀공학회지
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• 제29권10호
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• pp.1062-1069
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• 2012

This paper suggests a computational modeling to reflect static/dynamic characteristics of LM bearings. A theoretical study for modeling LM bearings is elucidated by using the Hertz contact theory, the Lagrange's equation of motion, normal mode analysis and a calculation of equivalent moment center. The complex geometry of LM bearings is replaced by a simplified model with eight springs only. The suggested model reflects static and dynamic characteristics of LM bearings without any consideration for the shape of the bed or stages on the LM bearings. The modal experimental results are compared to the simulation results with the suggested computational modeling. The difference between the experiments and simulation is calculated less than 8%.

• Advances in biomechanics and applications
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• 제1권3호
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• pp.143-158
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• 2014

Forearm fractures in children are very common among all pediatric fractures. However, biomechanical investigations on the pediatric forearm are rather scarce, partially due to the complex anatomy, closely situated, interrelated structures, highly dynamic movement patterns, and lack of appropriate tools. The purpose of this study is to develop a computational tool for child forearm investigation and characterize the mechanical responses of a backward fall using the computational model. A three-dimensional 10-year-old child forearm finite element (FE) model, which includes the ulna, radius, carpal bones, metacarpals, phalanges, cartilages and ligaments, was developed. The high-quality hexahedral FE meshes were created using a multi-block approach to ensure computational accuracy. The material properties of the FE model were obtained by scaling reported adult experimental data. The design of computational experiments was performed to investigate material sensitivity and the effects of relevant parameters in backward fall. Numerical results provided a spectrum of child forearm responses with various effective masses and forearm angles. In addition, a conceptual L-shape wrist guard design was simulated and found to be able to reduce child distal radius fracture.

• 한국전산유체공학회지
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• 제11권1호
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• pp.57-66
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• 2006

An optimal shape design approach is presented for a subsonic S-shaped intake using aerodynamic sensitivity analysis. Two-equation turbulence model is employed to capture strong counter vortices in the S-shaped duct more precisely. Sensitivity analysis is performed for the three-dimensional Navier-Stokes equations coupled with two-equation turbulence models using a discrete adjoint method For code validation, the result of the flow solver is compared with experiment data and other computational results of bench marking test. To study the influence oj turbulence models and grid refinement on the duct flow analysis, the results from several turbulence models are compared with one another and the minimum number of grid points, which can yield an accurate solution is investigated The adjoint variable code is validated by comparing the complex step derivative results. To realize a sufficient and flexible design space, NURBS equations are introduced as a geometric representation and a new grid modification technique, Least Square NURBS Grid Approximation is applied With the verified flow solver, the sensitivity analysis code and the geometric modification technique, the optimization of S-shaped intake is carried out and the enhancement of overall intake performance is achieved The designed S-shaped duct is tested in several off-design conditions to confirm the robustness of the current design approach. As a result, the capability and the efficiency of the present design tools are successfully demonstrated in three-dimensional highly turbulent internal flow design and off-design conditions.

• Wind and Structures
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• 제9권1호
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• pp.37-58
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• 2006

The paper describes a study about effects of upstream hills on design wind loads using two mathematical approaches: Computational Fluid Dynamics (CFD) and Artificial Neural Network (NN for short). For this purpose CFD and NN tools have been developed using an object-oriented approach and C++ programming language. The CFD tool consists of solving the Reynolds time-averaged Navier-Stokes equations and $k-{\varepsilon}$ turbulence model using body-fitted nearly-orthogonal coordinate system. Subsequently, design wind load parameters such as speed-up ratio values have been generated for a wide spectrum of two-dimensional hill geometries that includes isolated and multiple steep and shallow hills. Ground roughness effect has also been considered. Such CFD solutions, however, normally require among other things ample computational time, background knowledge and high-capacity hardware. To assist the enduser, an easier, faster and more inexpensive NN model trained with the CFD-generated data is proposed in this paper. Prior to using the CFD data for training purposes, extensive validation work has been carried out by comparing with boundary layer wind tunnel (BLWT) data. The CFD trained NN (CFD-NN) has produced speed-up ratio values for cases such as multiple hills that are not covered by wind design standards such as the Commentaries of the National Building Code of Canada (1995). The CFD-NN results compare well with BLWT data available in literature and the proposed approach requires fewer resources compared to running BLWT experiments.

• 컴퓨터교육학회논문지
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• 제20권6호
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• pp.27-36
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• 2017

오늘날 컴퓨팅 사고 과목은 초 중등 교육과정뿐만 아니라 고등 교육과정에서도 필수 영역으로 개설하고 있다. 특히 고등 교육과정에서는 학습자가 컴퓨팅 사고의 개념을 전공 분야에 실제로 적용할 수 있도록 교육하여 융합 인재의 기반을 마련하는 것이 중요하다. 그러나 이와 같은 목표에 맞는 교육이 이루어지고 있는지를 평가할 수 있는 도구와 관련 연구가 부족하다. 이에 본 연구에서는 비전공자를 대상으로 한 컴퓨팅 사고 과목을 개념 교육과 프로그래밍 실습 교육의 두 가지 관점으로 평가하는 루브릭을 개발하고 학습 성취도를 평가하고 이론과 실습간의 연관성을 분석하였다. 제안 루브릭은 고등 교육과정의 컴퓨팅 사고 개념 및 실습 학습을 평가하기 위하여 컴퓨팅 사고의 세부 요소를 4개의 분류 및 8가지의 항목으로 구성한 두 개의 루브릭을 정의하였다. 또한 제안 루브릭을 대학교 컴퓨팅 사고 관련 교양 수업에 적용하여 학습도를 평가하여 결과를 분석하고 향후 개선점을 도출하였다.

• 컴퓨터교육학회논문지
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• 제20권2호
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• pp.1-11
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• 2017

고등교육의 비전공자 대상 정보과학 교육의 수요가 늘고 있지만, 컴퓨팅 사고력 관점에서 적절하게 학생들의 창의적 산출물을 평가하는 도구는 부족하다. 이에 본 연구는 고등교육의 비전공자를 위한 정보 과학 수업에서 학생들이 개발한 창의적 산출물을 컴퓨팅 사고력 관점에서 평가하는 루브릭을 개발하기 위한 목적으로 진행되었다. 루브릭 초안의 준거틀(framework)은 CT Practices Design Pattern이며, 개발된 루브릭의 구성 요소는 영역, 역량요소, 평가요소, 평가자료, 평가단계의 다섯 가지이다. 루브릭은 '추상화 모델의 설계', '창의적 산출물의 설계 및 적용', 그리고 '산출물의 자가 평가'의 세 영역으로 구분하여 개발되었다. 전문가 검토를 통해 내용 타당성을 확보하였으며, 신뢰도 측면의 일관성이 검증되었다. 본 연구에서 개발된 루브릭은 해당 목적에 맞게 수정하여 사용할 수 있다.

• Advances in Computational Design
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• 제4권1호
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• pp.43-52
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• 2019

Variation Analysis (VA) is used to simulate final product variation, taking into consideration part manufacturing and assembly variations. In VA, all the manufacturing and assembly processes are defined at the product design stage. Process Capability Data Bases (PCDB) provide information about measured variation from previous products and processes and allow the designer to apply this to the new product. A new challenge to this traditional approach is posed by the Industry 4.0 (I4.0) revolution, where Smart Manufacturing (SM) is applied. The manufacturing intelligence and adaptability characteristics of SM make present PCDBs obsolete. Current tolerance analysis methods, which are made for discrete assembly products, are also challenged. This paper discusses the differences expected in future factories relevant to VA, and the approaches required to meet this challenge. Current processes are mapped using I4.0 philosophy and gaps are analysed for potential approaches for tolerance analysis tools. Matching points of simulation capability and I4.0 intents are identified as opportunities. Applying conditional variations, incorporating levels of adjustability, and the un-suitability of present Monte Carlo simulation due to changed mass production characteristics, are considered as major challenges. Opportunities including predicting residual stresses in the final product and linking them to product deterioration, calculating non-dimensional performances and extending simulations for process manufactured products, such as drugs, food products etc. are additional winning aspects for next generation VA tools.

• 정보관리학회지
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• 제16권4호
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• pp.53-74
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• 1999

본 논문에서는 효율적인 암묵적 지식을 표현하기위한 도구로써 개념매핑기법에 대해 기술을 하고 있다. 개념매핑기법은 비형식적인 것에서부터 형식적인기법까지 다양하다. 형식적개념매핑은 사용이 용이하지만 컴퓨터 처리능력이 없다. 반면에 비형식적 개념매핑은 추론능력은 있으나 사용이 어렵다는 단점이 있다. 따라서 미래의 지식매핑시스템은 형식적ㆍ비형식적 개념기법의 장점을 모두 고려해야 할 것으로 보인다.