• Title/Summary/Keyword: 선요소

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Design of Soft X-ray Tube and Simulation of Electron Beam by Using an Electromagnetic Finite Element Method for Elimination of Static Electric Field (전자기 유한요소법 전자빔 시뮬레이션을 이용한 정전기장 제거용 연한 X-선관 설계 특성 연구)

  • Park, Tae-Young;Lee, Sang-Suk;Park, Rae-Jun
    • Journal of the Korean Magnetics Society
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    • v.24 no.2
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    • pp.66-69
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    • 2014
  • The spreading tube of X-ray cathode tube displayed with an electromagnetic finite element method was designed. To analyze a feature design and the concrete coordinate performance of soft X-ray tube modeling, the orbit of electron beam was simulated by OPERA-3D SW program. The fixed conditions were the applied voltage, the temperature, the work function of thermal electron between cathode and anode of tungsten. Through the analysis of distribution of electron beam and the variation of dividing region, the design of soft X-ray spreading tube equipped with two cross filaments was optimized.

Geomorphological Mapping for Construction GIS Database of Geomorphic Elements (GIS Database 구축을 위한 지형 요소의 지도화)

  • 이민부;김남신;한균형
    • Journal of the Korean Geographical Society
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    • v.36 no.2
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    • pp.81-92
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    • 2001
  • 본 연구의 목적은 지형요소의 GIS Database 구축을 위한 전산화된 지형분류도 제작방안을 제시하는 것이다. 지형요소 전산화는 지형요소의 분류, 지형요소의 코드화, 범례화, 심볼의 제작, 마지막으로 지도화의 과정을 통하여 완성된다. 지형분류는 지형요소의 공간적 분포와 형태, 지형형성과 발달에 영향을 미치는 자연환경체계와 지형형성기구의 역할을 고려하며, 동적인 지형형성과정과 이 과정을 통해 물질관계를 파악할 수 있도록 하였다. 지형분류도는 1: 25,000 축적에 표현 가능한 지형요소를 나타낼 수 있도록 고려하였다. 지형요소들의 지도화 되었을 때는 시.공간적인 관계를 통해 지형환경체계가 인식되도록 하였다. 지형요소들은 GIS에서 Layer단위로 입력되어야 하기 때문에 Data Feature의 성격을 점.선.면으로 분류하여 지형요소의 형상을 범례로 만들었다. 지형요소 범례는 지형의 형태, 물질 그리고 성인을 고려하여 지형요소를 상징화할 수 있도록 설계하였다.

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A Study on Large Scale FEM for Structural Analysis of a Crane Vessel Using Superelement Technique (슈퍼요소기법을 이용한 대규모 유한요소법의 크레이선 구조해석 적용 연구)

  • 조규남;장영식;이지현
    • Computational Structural Engineering
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    • v.7 no.3
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    • pp.143-152
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    • 1994
  • Superelement technique for structural analysis of large scale objects such as airplanes or vessels is effective especially in the harsh hardware environments. In this paper, a crane vessel of OHI 5000 which is capable of lifting 5000 tons in tie-backs and capable of revolving with 3000 tons is investigated in the view point of structural safety using superelements through the substructure scheme. Also an effective substructure procedure, a unique load extraction method and finite element modeling technique are demonstrated. Comprehensive reinforcement blueprints are derived based on the analysis results. Successful application of substructure technique is achieved through the structural analysis of the crane vessel. The analysis technique developed in this paper can be a guideline for similar large scale structures' relevant safety identification.

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A study of modern metal craft using analytical formative beauty of line and surface (선과 면의 해석적 조형미를 활용한 현대금속공예 연구)

  • Ko, Seung Geun
    • Journal of Digital Convergence
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    • v.16 no.1
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    • pp.337-342
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    • 2018
  • This study was started to study the artistic aesthetic value of the antique artwork which is gradually declining in the field of metal crafts. The aesthetic interpretation of the lines and faces that have been identified through previous researches has been defined as a vitality and repetitive beauty. The researchers here have tried to express the formative works which can be repeated and change. As a result, it was found that the object of inquiry which can express the aesthetic beauty felt in the simple change of the line and the face is possible without the advanced technique of the difficult technique or the molding method through the natural and gradual change of the line and the face rather than the regular repetition. Through this study, it was found that the use of future lines and surfaces could be utilized as a variety of aesthetic expression methods as molding elements.

Acquirement of True Stress-strain Curve Using True Fracture Strain Obtained by Tensile Test and FE Analysis (인장시험과 유한요소해석으로 구한 파단 진변형률을 이용한 진응력-진변형률 선도 획득)

  • Lee, Kyoung-Yoon;Kim, Tae-Hyung;Lee, Hyung-Yil
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.33 no.10
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    • pp.1054-1064
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    • 2009
  • In this work, we predict a true fracture strain using load-displacement curves from tensile test and finite element analysis (FEA), and suggest a method for acquiring true stress-strain (SS) curves by predicted fracture strain. We first derived the true SS curve up to necking point from load-displacement curve. As the beginning, the posterior necking part of true SS curve is linearly extrapolated with the slope at necking point. The whole SS curve is then adopted for FE simulation of tensile test. The Bridgman factor or suitable plate correction factors are applied to pre and post FEA. In the load-true strain curve from FEA, the true fracture strain is determined as the matching point to test fracture load. The determined true strain is validated by comparing with test fracture strain. Finally, we complete the true SS curve by combining the prior necking part and linear part, the latter of which connects necking and predicted fracture points.

Automatic Extraction of Roof Components from LiDAR Data Based on Octree Segmentation (LiDAR 데이터를 이용한 옥트리 분할 기반의 지붕요소 자동추출)

  • Song, Nak-Hyeon;Cho, Hong-Beom;Cho, Woo-Sug;Shin, Sung-Woong
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.25 no.4
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    • pp.327-336
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    • 2007
  • The 3D building modeling is one of crucial components in building 3D geospatial information. The existing methods for 3D building modeling depend mainly on manual photogrammetric processes by stereoplotter compiler, which indeed take great amount of time and efforts. In addition, some automatic methods that were proposed in research papers and experimental trials have limitations of describing the details of buildings with lack of geometric accuracy. It is essential in automatic fashion that the boundary and shape of buildings should be drawn effortlessly by a sophisticated algorithm. In recent years, airborne LiDAR data representing earth surface in 3D has been utilized in many different fields. However, it is still in technical difficulties for clean and correct boundary extraction without human intervention. The usage of airborne LiDAR data will be much feasible to reconstruct the roof tops of buildings whose boundary lines could be taken out from existing digital maps. The paper proposed a method to reconstruct the roof tops of buildings using airborne LiDAR data with building boundary lines from digital map. The primary process is to perform octree-based segmentation to airborne LiDAR data recursively in 3D space till there are no more airborne LiDAR points to be segmented. Once the octree-based segmentation has been completed, each segmented patch is thereafter merged based on geometric spatial characteristics. The experimental results showed that the proposed method were capable of extracting various building roof components such as plane, gable, polyhedric and curved surface.

Three Dimensional Spatial Data Creation for Application of Virtual GIS (Virtual GIS 적용을 위한 3차원 공간데이터 작성)

  • 신석효;안기원
    • Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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    • 2002.04a
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    • pp.195-206
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    • 2002
  • 지리정보를 정보시스템에서 사용하기 위해서는 복잡한 실세계의 형상을 단순화, 일반화하여 전산적으로 처리할 수 있는 정보구조로 변환해야 한다. 기존의 2차원 GIS에서는 실세계의 형상을 점, 선, 면 등의 2차원적인 형상으로 수치 정보화 하여 GIS 기능을 수행하고 있다. 하지만 지구상에 존재하는 지리적인 요소들은 3차원적인 공간정보로 구성되므로 이를 2차원으로 추상화시키면 많은 정보의 손실이 일어나게 되며, 기존의 2차원 GIS는 근본적인 한계가 존재하게 된다. 따라서, 실세계의 3차원적인 지리요소는 컴퓨터 상에서도 3차원으로 처리하는 것이 지리요소가 원래 지니고 있는 정보의 손실을 최소화 할 수 있으며, 실세계의 자연물 및 인공 시설물에 대한 3차원적인 표현과 분석을 위해서는 궁극적인 형태의 3차원 GIS가 필요한 실정이다. 이에 본 연구에서는 점, 선, 면 등의 2차원적인 형상을 3차원 공간 데이터로 수치 정보화 하기 위한 수단으로 VRML(Virtual Reality Modeling Language)을 이용하여 Virtual GIS 적용을 위한 3차원 가상세계를 생성함으로서 각종 의사결정을 보다 효율적이고 시각적으로 행할 수 있는 공간데이터를 작성하고자 하였다.

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Analysis of Superplastic Forming Processes U sing Finite Element Method (유한요소법을 이용한 초소성 성형공정 해석)

  • 홍성석;김민호;김용환
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.19 no.6
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    • pp.1411-1421
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    • 1995
  • A rigid visco-plastic finite element method has been developed for modeling superplastic forming processes. The optimum pressure-time relationship for a target strain rate and thickness distributions was predicted using two-node line element based on membrane approximation for plane strain and axisymmetric condition. Analysis of superplastic forming was carried out using the developed program and the numerical results were compared to the values available in the literature for plane strain problems. For description of the contact between the dies and sheet, the direct projection method was applied to the complicated problem and the validity of the scheme was tested. Experiments for the various geometries such as hemisphere and cone were performed with the developed forming machine using the calculated optimum pressure-time curves. Comparison between analysis and experiments showed good agreement.

Three-dimensional finite element analysis of stress distribution for different implant thread slope and implant angulation (임플란트 나사선 경사각과 식립 각도에 따른 3차원 유한요소 응력분석)

  • Seo, Young-Hun;Lim, Hyun-Pil;Yun, Kwi-Dug;Yoon, Suk-Ja;Vang, Mong-Sook
    • The Journal of Korean Academy of Prosthodontics
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    • v.51 no.1
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    • pp.1-10
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    • 2013
  • Purpose: The purpose of this study was to find an inclination slope of the screw thread that is favorable in distributing the stresses to alveolar bone by using three dimensional finite element analysis. Materials and methods: Three types modelling changed implant thread with fixed pitch of 0.8 mm is the single thread implant with $3.8^{\circ}$ inclination, double thread implant with $7.7^{\circ}$ inclination and the triple thread implant with $11.5^{\circ}$ inclination. And three types implant angulation is the $0^{\circ}$, $10^{\circ}$ and $15^{\circ}$ on alveolar bone. The 9 modelling fabricated for three dimensional finite element analysis that restored prosthesis crown. The crown center applied on 200 N vertical load and $15^{\circ}$ tilting load. Results: 1. The more tilting of implant angulation, the more Von-Mises stress and Max principal stress is increasing. 2. Von-Mises stress and Max principal stress is increasing when applied $15^{\circ}$ tilting load than vertical load on the bone. 3. When the number of thread increased, the amount of Von-Mises stress, Max principal stress was reduced since the generated stress was effectively distributed. 4. Since the maximum principal stress affects on the alveolar bone can influence deeply on the longevity of the implants. When comparing the magnitude of the maximum principal stress, the triple thread implant had a least amount of stress. This shows that the triple thread implant gave a best result. Conclusion: A triple thread implant to increase in the thread slope inclination and number of thread is more effective on the distribution of stress than the single and double thread implants especially, implant angulation is more tilting than $10^{\circ}$ on alveolar bone. Thus, effective combination of thread number and thread slope inclination can help prolonging the longevity of implant.

전기통신회선의 명음 방지 규정과 기술동향

  • Gu, Bon-Hui;Kim, Yong-Hwan;Son, Heung
    • Electronics and Telecommunications Trends
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    • v.7 no.4
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    • pp.71-88
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    • 1992
  • 전기통신 회선의 2 선 선로 임피던스와 하이브리드 회로의 평형 결선망과의 임피던스 부정합에 의한 반사손실의 영향을 파악하고 과도한 중계기 이득과 이들 임피던스 부정합으로 인한 통신망의 위해요소인 명음의 발생 배경과 명음 발생 방지를 위한 세계 각국의 관련기준 및 측정법을 조사 분석한다.