• ETRI Journal
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• v.39 no.2
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• pp.234-244
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• 2017

Research interest in three-dimensional multiple-input multiple-output (3D-MIMO) beamforming has rapidly increased on account of its potential to support high data rates through an array of strategies, including sector or user-specific elevation beamforming and cell-splitting. To evaluate the full performance benefits of 3D and full-dimensional (FD) MIMO beamforming, the 3D character of the real MIMO channel must be modeled with consideration of both the azimuth and elevation domain. Most existing works on the 2D spatial channel model (2D-SCM) assume a wide range for the distribution of elevation angles of departure (eAoDs), which is not practical according to field measurements. In this paper, an optimal FD-MIMO planar array configuration is presented for different practical channel conditions by restricting the eAoDs to a finite range. Using a dynamic network level simulator that employs a complete 3D SCM, we analyze the relationship between the angular spread and sum throughput. In addition, we present an analysis on the optimal antenna configurations for the channels under consideration.

• Applied Microscopy
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• v.37 no.2
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• pp.143-146
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• 2007

The objects of the nature have three dimensional (3-D) parameters. The 3-D profiles are embedded on the photographs and microscopic images. To understand 3-D configuration, stereo pair image with thick section is frequently employed. The perception of 3-D images is possible with the aid of stereoscopic glasses, although the expert can perceive 3-D images without the glasses. Anaglyphic stereo images are constructed by various softwares from commercial and freeware. Here we would like to present an easy anaglyphs construction method with Adobe $Photoshop^{(R)}$ based on tilting paired images from high voltage electron microscope. The anaglyphic stereo images constructed revealed the same 3-D perception with conventional stereoscopy. We could zoom in/out the anaglyph image digitally to investigate the detail configuration by real time. This method is expected to contribute to understanding complex structures 3 dimensionally.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.12
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• pp.3148-3165
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• 1993

A cascade wind tunnel test for a turbine nozzle, which was designed for a small turbo jet engine in a previous study, has been conducted to evaluate its aerodynamic performance and losses. The large-scale blades were based on the mid-span profile of the nozzle. Oil film flow structure, and then 3-dimensional velocity components were measured in the flow passage with a 5-hold pressure probe, in addition to turbulent intensities at mid-span of cascade exit using a hot-wire anemometer. From this study, 3-dimensional growth of horseshoe and passage vortices in the downstream direction was clearly understood with near-wall flow phenomena. In addition, secondary flow and losses associated with the blade configuration were obtained in detail.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.05a
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• pp.1000-1007
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• 2007

In this study, structural vibration analyses of a smart unmanned aerial vehicle (UAV) have been conducted considering dynamic hub-loads of tilt rotor. Practical computational structural dynamics technique based on the finite element method is applied using MSC/NASTRAN. The present UAV(TR-S5-04) finite element model is constructed as a full three-dimensional configuration with different fuel conditions and tilting angles for helicopter, transient and airplane flight modes. In addition, the 3-dimensional supporting equipment structures of electronic devices are considered for vibration analysis. As the results of this study, transient structural displacements and accelerations are presented in detail. Moreover, vibration characteristics of structural parts and installed equipments are investigated for different fuel conditions and tilting angles.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.12
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• pp.1077-1083
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• 2014

Multi-material Additive Manufacturing (AM) is being focused to apply for direct manufacturing of a product. In this paper, a three-dimensional circuit device (3DCD) fabrication technology based on the multi-material AM technology was proposed. In contrast with conventional two-dimensional Printed Circuit Board (PCB), circuit elements and conducting wires of 3DCD are placed in threedimensional configuration at multiple layers of the structure. Therefore, 3DCD technology can improve design freedom of an electronic product. In this paper, 3DCD technology is proposed based on AM technology. Two types of 3DCD fabrication systems were developed based on the Stereolithography and the Fused Deposition Modeling technologies. And the 3DCD samples which have same function were fabricated, successfully.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.317-322
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• 1989

Effective computational strategies have been proposed in the evaluation of stiffness matrices of rigid-plastic finite element method widely used in simulation of metal forming processes. The stiffness matrices are expressed as the sum of stiffness matrices evaluated by reduced integration and Liu's stabilization matrices which control the occurrence os zero-energy mode due to excessive reduced integration. The proposed method has been applied to the solution of fundamental 3-dimensional problems. The results clarified that the deformed mesh configuration was remarkably stabilized and computation speed attained about 3 times as fast as that of conventional 3-dimensional analyses. Furthermore, computation speed increases by a factor 60 when parallel computation is introduced. This speed has a tendency to increase as the total degree of freedom increases. As a result, this rigid-plastic finite element method enables us to analyze real 3-dimensional forming processes with practically acceptable computation time.

• Journal of KIISE:Software and Applications
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• v.36 no.11
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• pp.960-966
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• 2009

A manifold is used to represent a relationship between high-dimensional data samples in low-dimensional space. In human pose estimation, it is created in low-dimensional space for processing image and 3D body configuration data. Manifold learning is to build a manifold. But it is vulnerable to silhouette variations. Such silhouette variations are occurred due to view-change, person-change, distance-change, and noises. Representing silhouette variations in a single manifold is impossible. In this paper, we focus a silhouette variation problem occurred by view-change. In previous view invariant pose estimation methods based on manifold learning, there were two ways. One is modeling manifolds for all view points. The other is to extract view factors from mapping functions. But these methods do not support one by one mapping for silhouettes and corresponding body configurations because of unsupervised learning. Modeling manifold and extracting view factors are very complex. So we propose a method based on triple manifolds. These are view manifold, pose manifold, and body configuration manifold. In order to build manifolds, we employ biased manifold learning. After building manifolds, we learn mapping functions among spaces (2D image space, pose manifold space, view manifold space, body configuration manifold space, 3D body configuration space). In our experiments, we could estimate various body poses from 24 view points.

• International Journal of Naval Architecture and Ocean Engineering
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• v.10 no.3
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• pp.250-258
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• 2018

Free Standing Hybrid Riser (FSHR) is comprised of vertical steel risers and Flexible Jumpers (FJ). They are jointly connected to a submerged Buoyancy Can (BC). There are several factors that have influence on the behavior of FSHR such as the span distance between an offshore platform and a foundation, BC up-lift force, BC submerged location and FJ length. An optimization method through a parametric study is presented. Firstly, descriptions for the overall arrangement and characteristics of FSHR are introduced. Secondly, a flowchart for optimization of FSHR is suggested. Following that, it is described how to select reasonable ranges for a parametric study and determine each of optimal configuration options. Lastly, numerical analysis based on this procedure is performed through a case study. In conclusion, the relation among those parameters is analyzed and non-dimensional parametric ranges on optimal arrangements are suggested. Additionally, strength analysis is performed with variation in the configuration.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.23 no.2
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• pp.335-344
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• 1993

The purpose of this study was to clarify the spatial relationship of temporomandibular joint and to an aid in the diagnosis of temporomandibular disorder. For this study, three-dimensional images of normal temporomandibular joints were reconstructed by computer image analysis system and three-dimensional reconstructive program integrated in computed tomography. The obtained results were as follows: 1. Two-dimensional computed tomograms had the better resolution than three dimensional computed tomograms in the evaluation of bone structure and the disk of TMJ. 2. Direct sagittal computed tomograms and coronal computed tomograms had the better resolution in the evaluation of the disk of TMJ. 3. The positional relationship of the disk could be visualized, but the configuration of the disk could not be clearly visualized on three-dimensional reconstructive CT images. 4. Three-dimensional reconstructive CT images had the smoother margin than three-dimensional images reconstructed by computer image analysis system, but the images of the latter had the better perspective. 5. Three-dimensional reconstructive images had the better spatial relationship of the TMJ articulation, and the joint spaces were more clearly visualized on dissection images.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.10
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• pp.1-6
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• 2006

This paper predicts the stall characteristics of three-dimensional wings. An iterative decambering approach is introduced into the nonplanar lifting surface method to take into consideration the stall characteristics of wings. An iterative decambering approach uses known airfoil lift curve and moment curve to predict the stall characteristics of wings. The multi-dimensional Newton iteration is used to take into consideration the coupling between the different sections of wings. Present results are compared with experiments and other numerical results. Computed results are in good agreement with other data. This scheme can be used for any wing with the twist or control surface and for wing-wing configurations such as wing-tail configuration or canard-wing configuration.