• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.557-561
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• 2014

In this work, Altair Engineering's vibroacoustic modeling approach is used to simulate the acoustic signature of a simplified automobile in a wind tunnel. The modeling approach relies on a two step procedure involving simulation and extraction of acoustic sources using a high fidelity Computational Fluid Dynamics (CFD) simulation followed by propagation of the acoustic energy within the structure and passenger compartment using a structural dynamics solver. The tools necessary to complete this process are contained within Altair's HyperWorks CAE software suite. The CFD simulations are performed using AcuSolve and the structural simulations are performed using OptiStruct. This vibroacoustics simulation methodology relies on calculation of the acoustic sources from the flow solution computed by AcuSolve. The sources are based on Lighthill's analogy and are sampled directly on the acoustic mesh. Once the acoustic sources have been computed, they are transformed into the frequency domain using a Fast Fourier Transform (FFT) with advanced sampling and are subsequently used in the structural acoustics model. Although this approach does require the CFD solver to have knowledge of the acoustic simulation domain a priori, it avoids modeling errors introduced by evaluation of the acoustic source terms using dissimilar meshes and numerical methods. The aforementioned modeling approach is demonstrated on the Hyundai Simplified Model (HSM) geometry in this work. This geometry contains flow features that are representative of the dominant noise sources in a typical automobile design; namely vortex shedding from the passenger compartment A-pillar and bluff body shedding from the side view mirrors. The geometry also contains a thick poroelastic material on the interior that acts to reduce the acoustic noise. This material is modeled using a Biot material formulation during the structural acoustic simulation. Successful prediction of the acoustic noise within the HSM geometry serves to validate the vibroacoustic modeling approach for automotive applications.

• 대한수학교육학회지:학교수학
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• 제6권2호
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• pp.153-179
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• 2004

본 연구에서는 모델링 과정의 활동을 세 가지 활동-지각적 활동, 인지적 활동, 메타인지적 활동-으로 구분하여 이 활동들의 상호작용으로 모델을 개발하는 과정을 중학교 학생들을 대상으로 사례연구 방법으로 조사하였다. 연구결과 학생들은 자신의 경험에 기반하여 과제상황을 이해하였고, 도구를 조작하는 지각적인 활동을 하면서 상황을 구조화하였다. 또한 지각적 활동에 기반하여 개발한 모델에 대해 사고하고 추론하는 인지적 활동을 재조직하면서 모델을 개발하였다. 아울러 메타인지적 활동을 통해 모델을 수정하고 정교화하여 일반화 가능한 모델을 개발하였다. 본 연구로부터 모델링 활동은 물리적 세계에서의 지각적인 활동과 추상적인 수학 활동을 연결함으로써 추상적인 수학 지식을 학생들이 이해하기 쉽게 지도할 수 있는 방법이라는 시사점을 얻을 수 있었다.

• 인터넷정보학회논문지
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• 제11권4호
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• pp.107-117
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• 2010

소프트웨어 제품들 사이의 공통된 개념과 서로 다른 개념들을 표현한 특성 모델과, 특정 제품에 포함될 특성들을 선택한 결과인 특성 구성은 소프트웨어 프러덕트 라인 개발 방법론에서 핵심 요소이다. 이들에 대한 정형적 시맨틱과 논리적 추론에 대한 연구가 진행 중이지만 시맨틱 웹 기술을 이용한 특성 모델 온톨로지 구축과 특성 구성 검증에 대한 연구는 아직 부족한 상황이다. 본 논문에서는 온톨로지와 시맨틱 웹 기술을 이용하여 특성 모델의 정형적 시맨틱을 정의하고 특성 구성을 검증하는 기법을 제안한다. 특성 모델과 특성 구성에 포함된 지식을 시맨틱 웹 표준 언어인 OWL(Web Ontology Language)로 표현하고 특성 구성을 검증하기 위한 규칙은 시맨틱 웹 규칙 언어인 SWRL(Semantic Web Rule Language)로 정의한다. 본 논문의 기법은, 특성 모델의 정형적 시맨틱을 제공하며 특성 구성 검증을 자동화할 뿐 만 아니라 SQWRL과 같은 다양한 시맨틱 웹 기술 적용을 가능하게 한다.

• STI Policy Review
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• 제8권1호
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• pp.113-156
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• 2017

Although technological progress is considered a key element for economic growth and development of a country, strong empirical evidence in this regard is not available yet. Therefore, to establish the empirical link between technology progress and economic development, it is advisable to carry out a time series analysis. In this regard, the Technology Achievement Index (TAI) of 100 top economies has been developed to examine the position of countries' technological progress for the 21 years spanning 1995 to 2015. Countries have been ranked on their TAI which is based on four pillars; technology creation, diffusion of older innovations, diffusion of recent innovations, and development of human skills. As well, this current study re-calculates the Humane Development Index (HDI) of 100 top economies for the 21 years from 1995 to 2015. Ranking of countries' HDI values reflects three dimensions: A long lifespan (life expectancy index), knowledge (Education Index) and a decent standard of living (Gross National Income Index, or GNI). The Standard Deviation (SD) technique has been used to investigate the technological gap between individual countries and groups of countries or regions. For a more meaningful assessment, technological gaps from the maximum achievement value (i.e., one of the countries under study) are presented as well. To investigate the impact of technological progress on economic development, this study introduces a model in which the HDI is used as the dependent variable and the TAI and Gross Capital Formation (GCF) are used as independent variables. The HDI, TAI and GCF are used in this model as proxy variables for economic development, technological progress and capital respectively. Econometric techniques have been used to show the impact of technological progress on economic development. The results show that long-term associations exist between technology progress and economic development; the impact of technology progress on economic development is 13.2% while the impact is 4.3% higher in eight selected East South Asian countries, at 13.5%, than in eight selected highly developed countries (9.2%).

• 산업경영시스템학회지
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• 제40권3호
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• pp.18-26
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• 2017

Defense industries which require high reliability need an optimized quality management system with well-planned implementation. And the government should examine the overall status of defense industries, then establish practical policies with a proper support plan in required areas to upgrade the quality management level of manufacturers. Thus, DTaQ developed the model for 2 years from 2014, which specialized in quality management level analysis for defense industries. And a survey has been undertaken with that model by DTaQ and Korea Research Center in 2016. The surveyed companies randomly sampled among those which have more than 30 employees and delivery history over past 3 years, and finally 106 defense industries were selected. This paper present survey method and indexes for survey of defense industry quality management level. The survey was conducted in the order of planning, data collection and data processing, and the validity and reliability of the data were verified to increase objectivity of survey results. The survey contents mainly consist of system quality and management quality. System quality includes Product Development Management, Production Operation Management, supply chain quality management, Safety & Environment Management and Reliability Management, on the other hand, management quality includes Strategic Leadership, Human Resource Management, Customer Market Management and Information & Knowledge Management. Thus this proposes the current overall quality management status of the 106 defense industries and shows level differences by company sizes and manufacturing sectors based on the result of survey. Specifically, this paper enables to track the areas which need prompt government support with the policy directions to make quality management level higher. Therefore, it is expected that this can be used as reference data in establishing quality policies for military supplies in the future.

• 디지털콘텐츠학회 논문지
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• 제11권4호
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• pp.607-614
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• 2010

가족이야기(familyHistory)를 중심으로한 지능형 스토리텔링 기획지원도구란 가족의 역사, 개인의 인물사등 선형적인 서사 장르의 이야기의 저작 과정을 지원하는 도구이다. 서사의 영역은 극, 신화, 전설, 역사 등의 언어적 서사물 뿐만 아니라, 영화, 연극, 발레, 오페라 등의 비언어적 서사도 포괄되나 본 연구에서는 언어적 서사물로서 각 가정의 구성원에 대한 인물사 및 가족역사를 중심으로 한다. 본 스토리텔링 기획 지원 도구는 샘플DB와 지식DB를 통하여 가정의 역사와 이야기에 대한 장르별 스토리텔링을 재구성하고, 내용의 가치와 완성도 높은 이야기를 구축하는데 있어서 적극적으로 활용 가능하다. 스토리텔링 기획에 소요되는 시간을 단축하고, 인력과 비용의 최소화를 지향 한다. 가족, 가정에 대한 스토리텔링은 창작 콘텐츠의 가장 원초적인 기반을 이루는 핵심적 단계이나 누구나 쉽게 접근하여 작성할 수 있는 기획 및 저작도구는 전무한 상태이다. 창작 인프라가 부족한 한국의 현황에서 본 연구가 제시한 기획지원도구는 대중이 쉽게 사용할 수 있고, 매커니즘을 개방화, 구조화 시킴으로서 향후 다양한 장르의 콘텐츠 창작 도구로 연동 가능한 모델을 설계하고 연구하고자 한다.

• Journal of Ship and Ocean Technology
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• 제12권1호
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• pp.16-27
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• 2008

The interaction between advancing ships and the waves generated by them plays important roles in wave resistances and ship motions. Wave breaking phenomena near the ship bow at different speeds are investigated both numerically and experimentally. Numerical simulations of free surface profiles near the fore bodies of ships are performed and visualized to grasp the general trend or the mechanism of wave breaking phenomena from moderate waves rather than concentrating on local chaotic irregularities as ship speeds increase. Navier-Stokes equations are differentiated based on the finite difference method. The Marker and Cell (MAC) Method and Marker-Density Method are employed, and they are compared for the description of free surface conditions associated with the governing equations. Extra effort has been directed toward the realization of extremely complex free surface conditions at wave breaking. For this purpose, the air-water interface is treated with marker density, which is used for two layer flows of fluids with different properties. Adaptation schemes and refinement of the numerical grid system are also used at local complex flows to improve the accuracy of the solutions. In addition to numerical simulations, various model tests are performed in a ship model towing tank. The results are compared with numerical calculations for verification and for realizing better, more efficient research performance. It is expected that the present research results regarding wave breaking and the geometry of the fore body of ship will facilitate better hull form design productivity at the preliminary ship design stage, especially in the case of small and fast ship design. Also, the obtained knowledge on the impact due to the interaction of breaking waves and an advancing hull surface is expected to be applicable to investigation of the ship bow slamming problem as a specific application.

• 한국결정성장학회:학술대회논문집
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• 한국결정성장학회 1996년도 제11차 KACG 학술발표회 Crystalline Particle Symposium (CPS)
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• pp.285-309
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• 1996

Non oxide ceramics such as nitrides of transition metals have shown significant potential for future economic impact, in diverse applications in ceramic, aerospace and electronic industries, as refractory products, abrasives and cutting tools, aircraft components, and semi-conductor substrates amid others. Combustion synthesis has become an attractive alternative to the conventional furnace technology to produce these materials cheaply, faster and at a higher level of purity. However he process os highly exothermic and manifests complex dynamics due to its strongly non-linear nature. In order to develop an understanding of this process and to study the effect of operational parameters on the final outcome, numerical modeling is necessary, which would generated essential knowledge to help scale-up the process. the model is based on a system of parabolic-hyperbolic partial differential equations representing the heat, mass and momentum conservation relations. The model also takes into account structural change due to sintering and volumetric expansion, and their effect on the transport properties of the system. The solutions of these equations exhibit steep moving spatial gradients in the form of reaction fronts, propagating in space with variable velocity, which gives rise to varying time scales. To cope with the possibility of extremely abrupt changes in the values of the solution over very short distances, adaptive mesh techniques can be applied to resolve the high activity regions by ordering grid points in appropriate places. To avoid a control volume formulation of the solution of partial differential equations, a simple orthogonal, adaptive-mesh technique is employed. This involves separate adaptation in the x and y directions. Through simple analysis and numerical examples, the adaptive mesh is shown to give significant increase in accuracy in the computations.

• Wind and Structures
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• 제14권4호
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• pp.285-300
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• 2011

Researchers at the International Hurricane Research Center (IHRC), Florida International University (FIU), are working in stages on the construction of a large state-of-the-art Wall of Wind (WoW) facility to support research in the area of Wind Engineering. In this paper, the challenges of simulating hurricane winds for the WoW are presented and investigated based on a scale model study. Three wind profiles were simulated using airfoils, and/or adjustable planks mechanism with and without grids. Evaluations of flow characteristics were performed in order to enhance the WoW's flow simulation capabilities. Characteristics of the simulated wind fields are compared to the results obtained from a study using computational fluid dynamics (CFD) and also validated via pressure measurements on small-scale models of the Silsoe cube building. Optimal scale of the test model and its optimal distance from the WoW contraction exit are determined - which are two important aspects for testing using an open jet facility such as the WoW. The main objective of this study is to further the understanding of the WoW capabilities and the characteristics of its test section by means of intensive tests and validations at small scale in order to apply this knowledge to the design of the full-scale WoW and for future wind engineering testing.

• 한국산학기술학회논문지
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• 제12권2호
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• pp.909-919
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• 2011

웹 사이트가 정보와 지식 습득을 위한 일상생활의 필수도구로 인식되면서 정보취약계층을 위한 웹 접근성이 중요시 되고 있다. 특히 2008년 장애인차별금지법의 시행으로 접근성 있는 웹 사이트의 제작이 의무화됨에 따라 웹 접근성 관련 전문 인력의 수요가 더욱 증가하고 있으나, 국내 대학의 정규 교육과정에서 웹 접근성 교육은 이루어지지 않고 있다. 이에 따라 본 논문에서는 타일러 모형과 교수체제 설계기법에 기반을 두고 국내 대학에서 활용 가능한 웹 접근성 교육과정을 개발하였다. 이를 위해 웹 접근성 교육목표를 설정하고, 국내 423개 대학과 국외 4개국의 197개 대학을 대상으로 웹 접근성 관련 교육현황 및 교육내용 구성과 특징을 분석하였다. 이를 바탕으로 웹 접근성 교육 내용을 구성하였고 웹 접근성 전문가 자문을 통해 이의 타당성을 검증하였다. 본 논문은 국내 대학이나 기관에서 웹 접근성 전문 인력 양성을 위한 교육과정의 기초자료로서 활용이 가능하다는 점에서 실무적인 공헌도가 있다.