• Title/Summary/Keyword: Three-dimensional Model

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FLOW SIMULATION AROUND DUCTED-PROP (덕티드-프롭 유동해석)

  • Choi, S.W.
    • 한국전산유체공학회:학술대회논문집
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    • 2007.10a
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    • pp.264-271
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    • 2007
  • The flow simulations around ducted-prop of tilt-duct aircraft were conducted in this study. For the investigation of aerodynamic characteristics of various configurations of duct, the axisymmetric flow calculation method combined with actuator disk model for prop were used. The rapid two-dimensional calculation and fast grid generation enable aerodynamic analysis for various duct configurations in a very short time and anticipated to active role in optimal configuration design of duct exposed to various flight modes. For the case of angle of attack or tilt angle, the three dimensional flow calculation is conducted using the three dimensional grid simply generated by just revolving the axisymmetric grid around center axis. Through the three dimensional calculation around duct, the aerodynamic effectiveness of duct as a lifting surface in airplane mode was investigated. The flow calculations around the control vane (wing) installed in the rear section of duct were conducted The aerodynamic data of wing were compared with the data of the ducts to evaluate the aerodynamic effectiveness of ducts.

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Automated FEA Simulation of Micro Motor (마이크로 모터의 자동화된 FEA 시뮬레이션)

  • Lee Joon-Seong
    • Journal of the Korea Society for Simulation
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    • v.11 no.3
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    • pp.13-22
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    • 2002
  • This paper describes an automated evaluation of electrostatic field for micro motors whose sizes range 10 to 103um. Electric field modeling in micro motors has been generally restricted to in-plane two-dimensional finite element analysis (FEA). In this paper, the actual three-dimensional geometry of the micro motor is considered. An automatic FE mesh generation technique, which is based on the fuzzy knowledge processing and computational geometry techniques, is incorporated in the system, together with one of commercial FE analysis codes and one of commercial solid modelers. The system allows a geometry model of concern to be automatically converted to different FE models, depending on physical phenomena to be analyzed, electrostatic analysis and stress analysis and so on. The FE models are then exported to the FE analysis code, and then analyses are peformed. Then, analytical analysis and FE analysis about the torque generated by electrostatic micro motor are performed. The starting torque is proportional to V2, the calculated starting torque from the two-dimensional analytical solutions are three times larger than those from the three-dimensional FE solutions.

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THREE-DIMENSIONAL VOLUME RECONSTRUCTION BASED ON MODIFIED FRACTIONAL CAHN-HILLIARD EQUATION

  • CHOI, YONGHO;LEE, SEUNGGYU
    • Journal of the Korean Society for Industrial and Applied Mathematics
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    • v.23 no.3
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    • pp.203-210
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    • 2019
  • We present the three-dimensional volume reconstruction model using the modified Cahn-Hilliard equation with a fractional Laplacian. From two-dimensional cross section images such as computed tomography, magnetic resonance imaging slice data, we suggest an algorithm to reconstruct three-dimensional volume surface. By using Laplacian operator with the fractional one, the dynamics is changed to the macroscopic limit of Levy process. We initialize between the two cross section with linear interpolation and then smooth and reconstruct the surface by solving modified Cahn-Hilliard equation. We perform various numerical experiments to compare with the previous research.

Quality Analysis of Three-Dimensional Geo-spatial Information Using Digital Photogrammetry (수치사진측량 기법을 이용한 3차원 공간정보의 품질 분석)

  • Lee, Hyun-Jik;Ru, Ji-Ho;Kim, Sang-Youn
    • Journal of Korean Society for Geospatial Information Science
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    • v.18 no.4
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    • pp.141-149
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    • 2010
  • Three-dimensional geo-spatial information is important for the efficient use and management of the country and the three-dimensional expression and analysis of urban projects, such as urban plans devised by local governments and urban management. Thanks to the revitalization of the geo-spatial information service industry, it is now being variously used not only in public but also private areas. For the creation of high-guiltily three-dimensional geo-spatial information, emphasis should be placed on not only the quality of the source image and three-dimensional geo-spatial model but also the level of visualization, such as level of detail and texturing. However, in the case of existing three-dimensional geo-spatial information, its establishment process is complicated and its data are not updated frequently enough, as it uses ready-created digital maps. In addition, as it uses Ortho Images, the images exist Relief displacement. As a result, the visibility is low and the three-dimensional models of artificial features are simplified to reach LoD between 2 and 3, making the images look less realistic. Therefore, this paper, analyzed the quality of three-dimensional geo-spatial information created using the three-dimensional modeling technique were applied using Digital photogrammetry technique, using digital aerial photo images by an existing large-format digital camera and multi-looking camera. The analysis of the accuracy of visualization information of three-dimensional models showed that the source image alone, without other visualization information, secured the accuracy of 84% or more and that the establishment of three-dimensional spatial information carried out simultaneously with filming made it easier to gain the latest data. The analysis of the location accuracy of true Ortho images used in the work process showed that the location accuracy was better than the allowable horizontal position accuracy of 1:1,000 digital maps.

An Inverse Dynamic Model of Upper Limbs during Manual Wheelchair Propulsion (수동 휠체어 추진 중 상지 역동역학 모델)

  • Song, S.J.
    • Journal of rehabilitation welfare engineering & assistive technology
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    • v.7 no.1
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    • pp.21-27
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    • 2013
  • Manual wheelchair propulsion can lead to pain and injuries of users due to mechanical inefficiency of wheelchair propulsion motion. The kinetic analysis of the upper limbs during manual wheelchair propulsion needs to be studied. A two dimensional inverse dynamic model of upper limbs was developed to compute the joint torque during manual wheelchair propulsion. The model was composed of three segments corresponding to upper arm, lower arm and hand. These segments connected in series by revolute joints constitute open chain mechanism in sagittal plane. The inverse dynamic method is based on Newton-Euler formalism. The model was applied to data collected in experiments. Kinematic data of upper limbs during wheelchair propulsion were obtained from three dimensional trajectories of markers collected by a motion capture system. Kinetic data as external forces applied on the hand were obtained from a dynamometer. The joint rotation angles and joint torques were computed using the inverse dynamic model. The developed model is for upper limbs biomechanics and can easily be extended to three dimensional dynamic model.

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THREE DIMENSIONAL FINITE ELEMENT ANALYSIS OF MANDIBULAR STRESSES UNDER COMPLETE DENTURES WITH VARIANT ARTIFICIAL TEETH FORMS AND OCCLUSAL PATTERNS (총의치 교합면 형태가 하악골 응력 분포에 미치는 영향에 관한 삼차원 유한요소분석적 연구)

  • Lee Cheol-Gyu;Kim Chang-Whe;Kim Yung-Soo
    • The Journal of Korean Academy of Prosthodontics
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    • v.31 no.3
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    • pp.351-384
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    • 1993
  • Complete denture occlusion must be developed to function efficiently and with the least amount of trauma to the supporting tissues. For the preservation of supporting tissues, it is imperative to reduce to a minimum the functional stress induced by dentures. The magnitude of the horizontal component of functional stress contributed by various occlusal teeth forms has not been studied. This study was aimed to investigate the influence of different occlusal teeth forms on the mode of distribution of the stresses in the mandibular tissue, and the displacement of lower dentures during the variant functional movement of mandible for this study three dimensional finite element analysis was used. FEM models were created using commercial software Super Sap for IBM 32 bit computer. The model was composed of 3380 brick elements and 4346 nodes. The results were as follows. 1. The magnitude of stress was similar between two models in centric occlusion, in the case of anatomic model, the stress was concentrated on the buccal side of alveolar ridge beneath the bicuspids. 2. During the protrusive movement, the increasing of stress from the posterior to anterior part of mandible was seen in the case of anatomic model. 3. During the lateral movement, the stress of anatomic model was greater than that of nonanatomic model. 4. The stress of anatomic model was concentrated on the anterior region of residual ridge during the lateral movement. 5. In the case of anatomic model the anterior part of denture was displaced severely at the centric and lateral position, but the denture of nonanatomic model was displaced minutely at the protrusive and lateral position.

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Construction of Land Information System using Three Dimensional Digital Elevation Model Algorithm (3차원 지형모델 알고리즘을 이용한 토지정보체계 구축)

  • Kang, Ho-Yun;Chang, Yong-Ku;Kang, In-Joon
    • Journal of the Korean Association of Geographic Information Studies
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    • v.4 no.3
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    • pp.31-40
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    • 2001
  • Geography Information System is divided to many details fields such as Urban Information System, Land Information System, Military Information System etc. These detailed fields are connected each other and make National Geography Information System. Now Geography Information System is being used in many fields with Urban Information System. And information of all field is being constructed to network for share each other. Now Land Information System(LIS) is being constructed to two dimensional. But LIS can construct and utilize three dimensional geographic data by connecting Geography Information System and this effect will be greatest. Thus, the study of connecting cadastral map and digital terrain map must be continued. Through the study of connecting digital terrain map, the construction and analysis of three dimensional digital elevation model will be able to construct Land Information System effectively. To this study, the authors constructed integrated geographic data by uniting digital terrain map and cadastral map and constructed three dimensional digital elevation model. By connecting cadastral information database, the authors developed three dimensional Integrated Land Information System.

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3-Dimensional Precision Measurement of Spacecraft Structure Test Model (위성체 구조시험 모델의 3차원 정밀 측정)

  • 윤용식;이중엽;조창래;이상설
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2001.04a
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    • pp.131-134
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    • 2001
  • The three-dimensional precision measurement technology for industry product of middle and/or large scale has been developed. Theodolite measurement system which is one of the technology is widely used in aerospace industry. This paper describes measurement method and results for spacecraft structure test model by using the measurement system. And structural stability for STM is desribed through the comparison between design values and measured values.

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Computational analysis of vortex breakup in arrhythmias (심장 부정맥 시 vortex breakup 현상에 대한 수치적 연구)

  • Shim, Eun-Bo;Kwon, Soon-Sung;Choi, Seung-Yoon
    • 한국전산유체공학회:학술대회논문집
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    • 2008.03b
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    • pp.496-497
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    • 2008
  • In this study, we present the computational analysis of cardiac arrhythmias that is the major cause of human sudden cardiac death. First, electric excitation and condution in one dimensional cardiac tissue model is solved and the results on condution block are represented. In two dimensional model, vortex daynamics in cardiac tissue is analyzed to delineate the breakup phenomenon inducing ventricular fibrillation. We also simulated a three dimenional heart model to see the vortex breakup and explained the mechanism in physiological aspect.

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