• Water Engineering Research
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• 제6권3호
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• pp.101-112
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• 2005

This paper presents the state of the art of the CFD applications to vegetated open-channel flows. First, important aspects of the physics of vegetated flows found through the laboratory experiments are briefly reviewed. Then, previous CFD applications to one-dimensional vertical structure, partly-vegetated flows, compound open-channel flows with floodplain vegetation, and fully three-dimensional numerical simulations are reviewed. Finally, topics for further researches such as relationship between the resistance and flexural rigidity, additional drag due to foliages, and melting the experience of CFD with the depth-averaged modeling, are suggested.

• 한국습지학회지
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• 제10권3호
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• pp.99-109
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• 2008

본 연구는 I편에서 개발된 일체형 블록시스템의 수리모형실험 결과를 검증하고 호안블록의 효과를 해석하기 위하여 수치해석을 통한 수리모형 실험을 수리특성을 모의하고자 하였다. 하도내 적용된 일체형 호안블록의 수치해석을 위하여 1차원 HEC-RAS 모형과 2차원 흐름 모의를 위하여 RMA-2 모형을 적용하여 식생전후의 수리현상을 수리모형 실험결과와 비교하여 홍수 시 유속 저감효과의 분석 및 대안으로 제시하는데 그 목적이 있다. 분석결과 2차원 수치해석 모형이 1차원 수치해석보다는 수위 유속 모두 수리모형실험결과와 근접한 결과를 나타내어 수치해석을 통한 자료구축 시 좀 더 신뢰성 있는 자료를 구축할 수 있는 것으로 판단되었다. 유속은 최저 0.21m/sec에서 최대 1.89m/sec의 저감효과를 나타내었으며, 이는 100m 당 4.89sec에서 7.33sec의 지체시간을 가져오는 것으로 분석되었다.

• 대한자원환경지질학회:학술대회논문집
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• 대한자원환경지질학회 1999년도 춘계 공동학술발표회
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• pp.74-76
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• 1999

• 지구물리와물리탐사
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• 제11권4호
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• pp.318-325
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• 2008

MT 모델링에서는 송신원을 고려하지 않으므로, 평면파에 대한 배경 매질의 반응을 경계값으로 설정하는 Dirichlet 경계조건을 이용할 때에 그 경계값의 정확한 계산이 매우 중요하다. 이 연구에서는 1차원 배경 매질만을 가정하던 기존의 모델링 알고리듬을 2차원 배경 매질을 고려할 수 있도록 발전시켰다. 1차원 배경매질의 경우 경계값은 해석적으로 계산할 수 있으나, 2차원 구조가 존재하는 경우에는 2차원 모델링을 통해 경계값을 계산하여야 한다. 2차원 모델링의 TM(transverse magnetic) 및 TE (transverse electric) 모드는 3차원 모델링의 입사 전기장의 분극 방향과 2차원 구조의 주향에 따라서 결정된다. 전기장을 셀 모서리에 정의하는 기존의 3차원 모델링 알고리듬과 잘 부합하도록 2차원 모델링에서도 모서리에서 전기장을 계산하였다. 2차원 모델링을 통해 계산된 값을 3차원 모델링의 경계값으로 활용한 결과, 단층 모형 혹은 한 면에 바다를 포함한 모형에 대해 보다 정확한 겉보기비저항 및 위상을 얻을 수 있었다.

• 한국전기전자재료학회논문지
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• 제16권12S호
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• pp.1157-1164
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• 2003

This paper shows the results of atomistic modeling for the interaction between spherical nano abrasive and substrate in chemical mechanical polishing processes. Atomistic modeling was achieved from 2-dimensional molecular dynamics simulations using the Lennard-Jones 12-6 potentials. The abrasive dynamics was modeled by three cases, such as slipping, rolling, and rotating. Simulation results showed that the different dynamics of the abrasive results the different features of surfaces. This model can be extended to investigate the 3-dimensional chemical mechanical polishing processes.

• 한국연소학회지
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• 제18권3호
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• pp.9-23
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• 2013

A rotary kiln furnace is one of the most widely used gas-solid reactors in the industrial field. Although the rotary kiln is a versatile system and has different size, approach to the reactor modeling can be generalized in terms of flow motion of the solid and gas phases, heat transfer, and chemical reactions on purpose. In this paper, starting from a zero-dimensional model and extending to higher dimension and comprehensive models, overall procedure of the design development of rotary kiln reactors and considerations are presented. The approaches to performance analysis of the reactors are introduced and examples of application cases are presented.

• 한국안전학회지
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• 제18권3호
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• pp.39-45
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• 2003

The failure mode of a pipe due to local wall thinning is increasingly more attention in the nuclear power plant industry. To assess the integrity of locally wall thinned pipe, it is necessary to perform many simulations under various conditions. Because the modeling for locally wall thinned elbow is more complicated than that of straight pipe the efficient modeling method for finite element analysis is necessary. In this study, the more simple efficient modeling method of three-dimensional finite element analysis for locally wall thinned elbow has been suggested and verified. And using the method, the failure mode of local wall thinned elbows that have different thinning lengths and circumferential angles is evaluated. From the results, we concluded that the collapse load of elbows has been decreased by the increase of wall thinning shape factors such as thinning lengths and circumferential angles.

• 한국BIM학회 논문집
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• 제13권3호
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• pp.1-11
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• 2023

In order to use BIM as a tool for improving the productivity and quality of products in the construction industry, a BIM model must be created from the design stage first. Infrastructure structures such as bridges and tunnels are mainly created based on three-dimensional alignment in the generation of BIM models. Especially, generation of BIM models based on three-dimensional linearity has high task difficulty and algorithms for automating BIM modeling for railway infra structures have been suggested in previous studies. This study improved the BIM modeling automation algorithm of railway infrastructures and developed a system based on the algorithm so that it can be easily used by ordinary users. The system was built as an add-in system of Autodesk's Revit. As an improvement first, it is possible to arrange different libraries for each pattern, enabling various uses. In addition, it can be created models of several members with a single process and the system can automatically places structures that are added periodically, such as Rock Bolt and Fore Polling. Finally, 3D length information and volume for each pattern are automatically calculated for more accurate 3D-based volume calculation. This study contributes to increasing user accessibility by building a BIM modeling automation algorithm into a system. The system is expected to improve the efficiency of BIM modeling creation of linear-based infra structures, including railway infrastructure.

• 한국재료학회지
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• 제18권11호
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• pp.592-596
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• 2008

Spring constants (displacement per unit applied load) of MEMS socket pins of given structures were computed by theoretical analysis and confirmed by the finite element method (FEM). In the theoretical analysis, the displacement of pins was calculated based on the 2-dimensional bending theory of the curved beam. For the 3-dimensional modeling, CATIA was used. After modeling, the raw data were transferred to ANSYS, which was employed in the 3-dimensional analysis for the calculation of the stress and strain and loaddisplacement The theoretical analysis and the FEM results were found to agree, with each showing the spring constants as 63.4 N/m within a reasonable load range. These results show that spring constants can be easily obtained through theoretical calculation without resorting to experiments and FEM analysis for simple and symmetric structures. For the some change of shape and structural stiffness, this theoretical analysis can be applied to MEMS socket pins.

• 한국철도학회:학술대회논문집
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• 한국철도학회 1998년도 창립기념 춘계학술대회 논문집
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• pp.564-571
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• 1998

The function of diaphragms at abutments and piers of prestressed concrete (PSC) box girder train bridge is to transfer forces from the superstructure onto bearings or column and to stiffen the superstructure cross-section against in-plane deformation. Due to large stress disturbance at diaphragm, the design for the diaphragm using conventional design method is relatively irrational than designs for other structual members. And, due to contribution to boundary condition of deck slab by the diaphragm, the behavior of deck slab near the diaphragm is different from behavior of the deck slab obtained from two dimensional analysis of the bridge, which is basis far the design of deck slab. In this paper, three dimensional behavior of deck slab near diaphragm of PSC box girder train bridge constructed by the precast span method are analyzed by using three dimensional finite element modeling. Then, strut-and-tie model is applied to design the diaphragm of PSC box girder train bridge. The modeling techniques in this paper can be applied effectively to examine the causes of cracks at deck slab near diaphragm and to design diaphragm rationally.