• Title/Summary/Keyword: Three-dimensional Model

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Numerical Simulation of Selective Withdrawal in Stably Stratified Flows (안정성층류에서 선택취수의 수치해석)

  • Paik, Joong-Cheol
    • Journal of Korea Water Resources Association
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    • v.38 no.11
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    • pp.973-984
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    • 2005
  • A three-dimensional thermal hydrodynamic model is developed for carrying out unsteady simulation of the selective withdrawal of the stably stratified flow in a geometrically complex, natural reservoir The governing equations are discretized on a non-staggered grid using a second-order accurate, finite-volume scheme. The numerical model is validated by applying it to simulate three-dimensional, turbulent, stratified, shear-layer flow case. The numerical predictions appear to capture reasonably well the general shape of velocity and temperature profiles observed in the laboratory experiments, while significant overestimation of the magnitude of velocity profiles is observed in the application to the flow in a natural reservoir. The physics of selective withdrawal as emerge from the numerical simulations are also discussed.

3D Printed Titanium Implant for the Skull Reconstruction: A Preliminary Case Study

  • Choi, Jong-Woo;Ahn, Jae-Sung
    • Journal of International Society for Simulation Surgery
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    • v.1 no.2
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    • pp.99-102
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    • 2014
  • The skull defect can be made after the trauma, oncologic problems or neurosurgery. The skull reconstruction has been the challenging issue in craniofacial fields for a long time. So far the skull reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for skull reconstruction, donor site morbidity would be the inevitable problem in many cases. Meanwhile various types of allogenic and alloplastic materials have been also used. However, skull reconstruction with many alloplastic material have produced no less complications including infection, exposure, and delayed wound healing. Because the 3D printing technique evolved so fast that 3D printed titanium implant were possible recently. The aim of this trial is to try to restore the original skull anatomy as possible using the 3D printed titanium implant, based on the mirrored three dimensional CT images based on the computer simulation. Preoperative computed tomography (CT) data were processed for the patient and a rapid prototyping (RP) model was produced. At the same time, the uninjured side was mirrored and superimposed onto the traumatized side, to create a mirror-image of the RP model. And we fabricated Titanium implant to reconstruct three-dimensional orbital structure in advance, using the 3D printer. This prefabricated Titanium-implant was then inserted onto the defected skull and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be very successful in this patient. Individualized approach for each patient could be an ideal way to manage the traumatic patients in near future.

A Study on Localization System using 3D Triangulation Algorithm based on Dynamic Allocation of Beacon Node (비컨노드의 동적배치 기반 3차원 삼각측량 알고리즘을 적용한 위치인식 시스템에 대한 연구)

  • Lee, Ho-Cheol;Lee, Dong-Myung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.4B
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    • pp.378-385
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    • 2011
  • The three-dimensional triangulation algorithm that the beacon nodes can be allocated to dynamically in not the experimental region but the practical region is suggested, and the performance of the localization system adapting the suggested algorithm is analyzed. The suggested algorithm adapts the computation method of the three dimensional point that the surfaces of three spheres overlapped, while the traditional triangulation algorithm adapts the computation method of the two dimensional point that three circles are overlapped in order to compute the distance between beacon nodes and mobile node that means a radius. In addition to this, to analyze the performance of the localization system adapting the suggested algorithm, first of all, the allocation layout of beacon nodes is made, and the allocation layout is modeled by selection of ten random distance values between mobile node and beacon nodes for computer simulation of the practical model. Next, the two dimensional coordinator of mobile node that is calculated by the suggested algorithm and the traditional triangulation algorithm is compared with each other. The localization measuring performance about three dimensional coordinator(z axis) of the suggested algorithm is also obtained by comparing with that of the practical model.

A new three-dimensional model for free vibration analysis of functionally graded nanoplates resting on an elastic foundation

  • Mahsa Najafi;Isa Ahmadi;Vladimir Sladek
    • Steel and Composite Structures
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    • v.52 no.3
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    • pp.273-291
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    • 2024
  • This paper presents a three-dimensional displacement-based formulation to investigate the free vibration of functionally graded nanoplates resting on a Winkler-Pasternak foundation based on the nonlocal elasticity theory. The material properties of the FG nanoplate are considered to vary continuously through the thickness of the nanoplate according to the power-law distribution model. A general three-dimensional displacement field is considered for the plate, which takes into account the out-of-plane strains of the plate as well as the in-plane strains. Unlike the shear deformation theories, in the present formulation, no predetermined form for the distribution of displacements and transverse strains is considered. The equations of motion for functionally graded nanoplate are derived based on Hamilton's principle. The solution is obtained for simply-supported nanoplate, and the predicted results for natural frequencies are compared with the predictions of shear deformation theories which are available in the literature. The predictions of the present theory are discussed in detail to investigate the effects of power-law index, length-to-thickness ratio, mode numbers and the elastic foundation on the dynamic behavior of the functionally graded nanoplate. The present study presents a three-dimensional solution that is able to determine more accurate results in predicting of the natural frequencies of flexural and thickness modes of nanoplates. The effects of parameters that play a key role in the analysis and mechanical design of functionally graded nanoplates are investigated.

Three-dimensional Equivalent Transient Ground Heat Exchanger Thermal Analysis Model by Considering Heating and Cooling Operations in Buildings (건물의 냉난방 운전을 고려한 3차원 동적 지중 열교환기 열해석 모델)

  • Baek, Seung Hyo
    • Land and Housing Review
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    • v.9 no.4
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    • pp.25-32
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    • 2018
  • Application of geothermal energy in buildings has been gaining popularity as it provides the benefits of both heating and cooling a building. Among the various types of geothermal energy systems, ground-coupled heat pump system is the most commonly applied one in South Korea. A ground heat exchanger plays an important role as a heat source in winter and a heat sink in summer. For the stable operation of a ground-coupled heat pump system, a ground heat exchanger should be sized so that it provides sufficient heating and cooling energy. Heating and cooling energies generated in ground heat exchangers mainly depend on the temperature difference between the heating medium in ground heat exchangers and the surrounding ground. In addition, the performance of ground heat exchangers influences the change in ground temperature. Therefore, it is necessary to consider this interrelation between the change in the ground temperature and the performance of ground heat exchanger for an accurate estimation of its performance. However, previous thermal analysis models for ground heat exchangers are not competent enough to allow a complete understanding of this interrelation. Therefore, this study proposes a three-dimensional equivalent, transient ground heat exchanger analysis model. First, a previous thermal analysis model for ground heat exchangers, including an analytical model, a g-function, and a numerical model are analyzed. Next, to overcome the limitations of the previous models, a three-dimensional equivalent, transient ground heat exchanger model is proposed. Finally, this study validated the proposed model with the measurement data of the thermal response test, sandbox test, and TRNSYS DST model. All validation results showed a good agreement. These findings helped us to investigate the thermal performance of ground heat exchangers more accurately than the analytical models, and faster than the numerical models. Furthermore, the proposed model contributes to the design of ground heat exchangers by considering the different operation conditions of buildings.

Effects of Thermal Contact Resistance on Film Growth Rate in a Horizontal MOCVD Reactor

  • Im Ik-Tae;Choi Nag Jung;Sugiyama Masakazu;Nakano Yoshiyaki;Shimogaki Yukihiro;Kim Byoung Ho;Kim Kwang-Sun
    • Journal of Mechanical Science and Technology
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    • v.19 no.6
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    • pp.1338-1346
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    • 2005
  • Effects of thermal contact resistance between heater and susceptor, susceptor and graphite board in a MOCVD reactor on temperature distribution and film growth rate were analyzed. One-dimensional thermal resistance model considering thermal contact resistance and heat transfer area was made up at first to find the temperature drop at the surface of graphite board. This one-dimensional model predicted the temperature drop of 18K at the board surface. Temperature distribution of a reactor wall from the three-dimensional computational fluid dynamics analysis including the gap at the wafer position showed the temperature drop of 20K. Film growth rates of InP and GaAs were predicted using computational fluid dynamics technique with chemical reaction model. Temperature distribution from the three-dimensional heat transfer calculation was used as a thermal boundary condition to the film growth rate simulations. Temperature drop due to the thermal contact resistance affected to the GaAs film growth a little but not to the InP film growth.

Development of Prediction Model for Flexibly-reconfigurable Roll Forming based on Experimental Study (실험적 연구를 통한 비정형롤판재성형 예측 모델 개발)

  • Park, J.W.;Kil, M.G.;Yoon, J.S.;Kang, B.S.;Lee, K.
    • Transactions of Materials Processing
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    • v.26 no.6
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    • pp.341-347
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    • 2017
  • Flexibly-reconfigurable roll forming (FRRF) is a novel sheet metal forming technology conducive to produce multi-curvature surfaces by controlling strain distribution along longitudinal direction. Reconfigurable rollers could be arranged to implement a kind of punch die set. By utilizing these reconfigurable rollers, desired curved surface can be formed. In FRRF process, three-dimensional surface is formed from two-dimensional curve. Thus, it is difficult to predict the forming result. In this study, a regression analysis was suggested to construct a predictive model for a longitudinal curvature of FRRF process. To facilitate investigation, input parameters affecting the longitudinal curvature of FRRF were determined as maximum compression value, curvature radius in the transverse direction, and initial blank width. Three-factor three-level full factorial experimental design was utilized and 27 experiments using FRRF apparatus were performed to obtain sample data of the regression model. Regression analysis was carried out using experimental results as sample data. The model used for regression analysis was a quadratic nonlinear regression model. Determination factor and root mean square root error were calculated to confirm the conformity of this model. Through goodness of fit test, this regression predictive model was verified.

Detection of Foreign Body in Esophageal Foreign Body Model Using Three Dimensional Reconstruction Technique (식도 이물 모델에서 이물 탐색을 위한 삼차원 재구성법의 활용)

  • Woo, Kuk Sung;Yoo, Young Sam;Kim, Dong Won
    • Korean Journal of Bronchoesophagology
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    • v.18 no.1
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    • pp.13-18
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    • 2012
  • Objective This study was conducted to gather basic information of 3D CT in detecting and gaining information of esophageal foreign body (FB) models. Materials and Methods The chest model was made using PVC bottle, rubber balloon and plaster. Fish bone, Persimmon stone were used to mimic foreign bodies of esophageal model. The foreign body models were inserted into the balloon removing air from it and the balloon was sealed. The esophageal FB model was inserted into the chest model. The remaining space in the chest model was filled with fish paste and water to simulate soft tissue around esophagus. CT of chest model was reconstructed three-dimensionally by Rapidia software to make images of foreign body models. The axial CT, MPR image and VOI image were compared with real foreign body materials as to shape, size, location and orientation. Results Esophageal FB models were easily made. CT data gave good 3D images and showed realistic foreign body materials. Conclusion The results indicate the usefulness of 3D CT technique to help in diagnosis of esophageal foreign body models.

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implementation of 3D Reconstruction using Multiple Kinect Cameras (다수의 Kinect 카메라를 이용한 3차원 객체 복원 구현)

  • Shin, Dong Won;Ho, Yo Sung
    • Smart Media Journal
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    • v.3 no.4
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    • pp.22-27
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    • 2014
  • Three-dimensional image reconstruction allows us to represent real objects in the virtual space and observe the objects at arbitrary view points. This technique can be used in various application areas such as education, culture, and art. In this paper, we propose an implementation method of the high-quality three-dimensional object using multiple Kinect cameras released from Microsoft. First, We acquire color and depth images from triple Kinect cameras; Kinect cameras are placed in front of the object as a convergence form. Because original depth image includes some areas where have no depth values, we employ joint bilateral filter to refine these areas. In addition to the depth image problem, there is an color mismatch problem in color images of multiview system. In order to solve it, we exploit an color correction method using three-dimensional geometry. Through the experimental results, we found that three-dimensional object which is used the proposed method is more naturally represented than the original three-dimensional object in terms of the color and shape.

Nonlinear Model of FRP-Confined Concrete Members Considering with Three-Dimensional Behaviors (3차원 거동에 의한 원형 FRP-구속 콘크리트의 부재 비선형 모델)

  • Cho Chang-Geun;Kwon Minho;Park Moon-Ho;Kim Wha-Jung;Bae Soo-Ho
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.05a
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    • pp.738-741
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    • 2004
  • This study is concerning on modeling to predict the flexural behaviors of FRP-confined concrete structural members. For compressive behaviors of confined concrete by FRP jackets, the hypoelasticity-based constitutive law of concrete has been presented under the basis of three-dimensional stress states. The strength enhancement of concrete wrapped by FRP jackets has been determined by the failure surface of concrete in tri-axial states, and its corresponding peak strain is computed by the strain enhancement factor. The behavior of FRP jackets has been modeled using the mechanics of orthotropic laminated composite materials in two-dimensional stress states. To be based on the three-dimensional constitutive laws, an algorithm for the prediction of flexural bending behaviors of FRP-confined concrete structural member has been presented.

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