• Title/Summary/Keyword: Nodal Line

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Nodal method for handling irregularly deformed geometries in hexagonal lattice cores

  • Seongchan Kim;Han Gyu Joo;Hyun Chul Lee
    • Nuclear Engineering and Technology
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    • v.56 no.3
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    • pp.772-784
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    • 2024
  • The hexagonal nodal code RENUS has been enhanced to handle irregularly deformed hexagonal assemblies. The underlying RENUS methods involving triangle-based polynomial expansion nodal (T-PEN) and corner point balance (CPB) were extended in a way to use line and surface integrals of polynomials in a deformed hexagonal geometry. The nodal calculation is accelerated by the coarse mesh finite difference (CMFD) formulation extended to unstructured geometry. The accuracy of the unstructured nodal solution was evaluated for a group of 2D SFR core problems in which the assembly corner points are arbitrarily displaced. The RENUS results for the change in nuclear characteristics resulting from fuel deformation were compared with those of the reference McCARD Monte Carlo code. It turned out that the two solutions agree within 18 pcm in reactivity change and 0.46% in assembly power distribution change. These results demonstrate that the proposed unstructured nodal method can accurately model heterogeneous thermal expansion in hexagonal fueled cores.

위상적 Dirac Nodal Line을 가지는 fcc Ca과 hcp Be의 전자 구조 계산 연구

  • 야나노세 구니히로
    • Proceeding of EDISON Challenge
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    • 2017.03a
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    • pp.463-467
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    • 2017
  • 본 연구에서는 위상적 Dirac nodal line 준금속으로 알려진 fcc 구조의 Ca과 hcp 구조의 Be에 대하여 LCPAO (Linear Combination of Pseudo Atomic Orbital) 방법을 이용하는 코드인 OpenMX를 통해 제일원리 전자 구조 계산을 수행하였다. 그 결과로 두 물질에서 밴드의 교차가 일어남을 확인하였으며, 준금속적인 성질이 있음을 확인하였다. 끝으로 EDISON의 사이언스 앱을 이용한 물질의 위상적 특성에 대한 연구의 가능성을 살펴보았다.

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Optimum Design of Trimming Line by One-Step Analysis for Auto Body Parts (역해석을 이용한 차체 부재의 트리밍라인 최적설계)

  • Bao, Y.D.;Huh, H.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2006.06a
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    • pp.49-54
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    • 2006
  • During most of manufacturing processes of auto-body panels, the trimming line should be designed in advance prior to flanging. It is an important task to find a feasible trimming line to obtain a precise final part shape after flanging. This paper proposes a new fast method to find feasible trimming line based on one-step analysis. The basic idea of the one-step analysis is to seek for the nodal positions in the initial blank from the final part, and then the distribution of strain, stress and thickness in the final configuration can be calculated by comparing the nodal position in the initial blank sheet with the one of the final part. The one-step analysis method is able to predict the trimming line before flanging since the desired product shape after flanging can be defined from the final configuration and most of strain paths are simple during the flanging process. Finally, designers can obtain a discrete trimming line from the boundary of the developed meshes after one-step analysis and import it into CAD system in the early design stage. The proposed method has been successfully applied to two basic curve flanging processes demonstrating many advantages.

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Development of Approximate Calculation Methodology for Nodal Price by Unit Priority-order and Loadflow (발전기 우선투입법 및 조류계산에 의한 개략모선가격 산정법 개발)

  • Lee, Buhm;Kim, Yong-Ha;Choi, Nam-Sup
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2003.10a
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    • pp.780-784
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    • 2003
  • This parer propose a new method to calculate nodal price which is very useful data in electric market under non-optimal operation. To calculate nodal price, we employ marginal cost and power flow, and consider network loss, generator capability, and line capability. The proposed method is applied to the test system and the usefulness is verified.

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On the Numerical Procedure for Estimating Structural Stress of Welded Structures (수치해석을 통한 용접구조물의 구조응력 추정에 관한 연구)

  • Kang, Sung-Won;Kim, Myung-Hyun
    • Journal of the Society of Naval Architects of Korea
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    • v.42 no.4 s.142
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    • pp.388-395
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    • 2005
  • A numerical procedure is proposed as a mesh-size insensitive structural stress definition that gives a stress state at a weld toe with relatively large mesh size. The structural stress values obtained using different finite element types, i.e. shell element and solid element, are examined for typical weld structures. The calculation procedures are performed using the balanced nodal forces and moments obtained from finite element solutions. A consistent formulation based on work equivalent argument has been implemented to transform the balanced nodal forces and moments from shell to line force and line moments at each nodal position. The mesh-insensitivity, the effect of distance $\delta$(where the stress is calculated) and the potential limitations of the structural stress method are examined for various types of weldments. Based on the results from this study, it is expected to develop a more precise stress estimation technique for fatigue strength assessment of welded structures.

Strategy for refinement of nodal densities and integration cells in EFG technique

  • Patel, Bhavana S.S.;Narayan, Babu K.S.;Venkataramana, Katta
    • Structural Engineering and Mechanics
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    • v.59 no.5
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    • pp.901-920
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    • 2016
  • MeshFree methods have become popular owing to the ease with which high stress gradients can be identified and node density distribution can be reformulated to accomplish faster convergence. This paper presents a strategy for nodal density refinement with strain energy as basis in Element-Free Galerkin MeshFree technique. Two popular flat plate problems are considered for the demonstration of the proposed strategies. Issue of integration errors introduced during nodal density refinement have been addressed by suggesting integration cell refinement. High stress effects around two symmetrical semi-circular notches under in-plane axial load have been addressed in the first problem. The second considers crack propagation under mode I and mode II fracture loading by the way of introducing high stress intensity through line crack. The computational efficacy of the adaptive refinement strategies proposed has been highlighted.

EXPRESSIONS OF METASTASIS-RELATED FACTORS IN ORTHOTOPIC TUMOR MODELS OF ORAL SQUAMOUS CELL CARCINOMA (구강 편평상피세포암 동위종양 모델에서 전이관련 인자의 발현)

  • Park, Young-Wook;Lee, Jong-Won;Kim, So-Hee
    • Maxillofacial Plastic and Reconstructive Surgery
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    • v.30 no.6
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    • pp.529-539
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    • 2008
  • Background and Purpose : Oral squamous cell carcinoma (OSCC) is one of the most aggressive tumors of the head and neck area. OSCC is known to preferentially metastasize via lymphatic system, and resulting cervical lymph node metastasis is the most reliable of treatment failure. But the biological mechanism of the regional nodal metastasis is not clear. So, we determined metastasis-related factors in orthotopic nude mouse models of OSCC. Experimental Design : Two cell lines-KB and YD-10B cells, established from human oral mucosal squamous cell carcinoma, were xenografted into the tissue space of athymic murine mouth floor. The mice were followed for tumor development and growth, the murine tumors were examined histopathologically for local invasion or regional or distant metastasis. Finally, we performed immunohistochemical assays with antiepithelial growth factor (EGF), EGF receptor (EGFR), phosphorylated EGFR (pEGFR), and anti-vascular endothelial growth factor (VEGF), VEGF receptor (VEGFR)-2, phosphorylated VEGFR-2/3 (pVEGFR-2/3) antibodies. We also determined the microvessel density. Results : Transplantation of human OSCC tumor cells into the mouth floor successfully resulted in the formation of orthotopic tumors. KB cell line showed significantly higher tumor proliferation and higher nodal metastatic potential than YD-10B cell line. Furthermore, immunohistochemical staining demonstrated higher expression of EGFR/pEGFR, VEGF, and pVEGFR-2/3 as well as higher microvessel density in KB murine tumors than in YD-10B murine tumors. Conclusion : An orthotopic model of OSCC in athymic mice was established which copies the cervical lymph nodal metastasis of human OSCC. Our mouth floor model should facillitate the understanding of the molecular pathogenesis of cervical nodal metastasis of OSCC.

Analysis of Progressive Fracture in Concrete using Finite Elements with Embedded Discontinuous Line (내부 불연속 요소를 사용한 콘크리트의 파괴진행해석)

  • 송하원;우승민;김형운
    • Proceedings of the Korea Concrete Institute Conference
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    • 1998.10a
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    • pp.450-455
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    • 1998
  • In this paper, finite element with embedded discontinuous line is introduced in order to avoid the difficulties of adding new nodal points along with crack growth in discrete crack model. With the discontinuous element using discontinuous shape function, stiffness matrix of finite element is derived and dual mapping technique for numerical integration is employed. Using the finite element program made with employed algorithms, algorithm is verified and fracture analysis of simple concrete beam is performed.

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The design of the traction power supply for the test line of Light Rail Vehicle (경전철 시험선용 전력공급시스템 설계)

  • 김국진;백병산;전용주;정상기;김남규
    • Proceedings of the KSR Conference
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    • 2001.10a
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    • pp.322-328
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    • 2001
  • In the electric railway systems, it is very important that we should design the system configuration, location and power capacity of substation. This paper presents the results of system configuration and system design of the DC traction power supply for the test line of Light Rail Vehicle. The voltage fluctuation of train and the power capacity of substation are calculated by computer simulation using the nodal equation, K.C.L/K.V.L, Ohm's law and superposition theory.

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Vibration analysis of the plates subject to dynamic concentrated loads by using spectral element method (스펙트럴요소법을 이용한 동적집중하중을 받는 평판의 진동해석)

  • Lee, Joon-Keun;Lee, U-sik
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.22 no.3
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    • pp.635-643
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    • 1998
  • A spectral element method(SEM) is introduced for the vibration analysis of a rectangular plate subject to dynamic concentrated loads. First, the spectral plate element is derived from the relations between the forces and displacements along the two opposite edges of plate element. The global spectral matrix equation is then formulated by assembling two spectral plate elements so that the dynamic concentrated load is located at the connection nodal line between two plate elements. the concentrated load is then spatially Fourier transformed in the direction of the connection nodal line to transform the two-dimensional plate problem into a simplified equivalent one-dimensional beam-like problem. We may benefit from these procedures in that the spectral results from the present SEM is compared with the exact analytical solutions to prove the remarkable accuracy of the present SEM, while this is not true for conventional finite element solutions, especially at high frequency.