• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.10
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• pp.4759-4780
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• 2017

Full Dimension multiple input multiple output (FD-MIMO) architecture employs a planar array design at the Base Station (BS) to provide high order multi-user MIMO (MU-MIMO) via simultaneous data transmission to large number of users. With FD-MIMO, the BS can also adjust the beam direction in both elevation and azimuth direction to concentrate the energy on the user of interests while minimizing the interference leakage to co-scheduled users in the same cell or users in the neighboring cells. In a typical highly populated macrocell environment, modelling the elevation angular characteristics of three-dimensional (3D) channel is critical to understanding the performance limits of the FD-MIMO system. In this paper, we study the throughput performance of FD-MIMO system with varying elevation angular spread and inter-element spacing using a 3D spatial channel model. Our results show that for a typical urban scenario, horizontal beamforming with correlated antenna spacing achieves optimal performance but by restricting the spread of elevation angles of departure, elevation beamforming achieves high array gain with wide inter-element spacing. We also realize significant gains due to spatial array processing via modelling the elevation domain and varying the inter-element spacing for both the transmitter and receiver.

• Journal of the HCI Society of Korea
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• v.12 no.2
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• pp.21-29
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• 2017

While the second and the third industrial revolutions made it possible a few standardized designs to be extracted and produced in large quantities, the recent development of the 3D printing technology allowed many individuals to reflect their unique personal characteristics on their creative works and produce them in large quantities-i.e., personally customized designs and mass production of various designs. However, for the customized designs and the mass production of various designs through the 3D printing technology, the individuals should use a 3D modeling software and the supporting features of the software can significantly affect the type and shape of a creative work. In this study, we surveyed the individuals who design the creative works using 3D printers about the type of software that they use and the type of creative works that they design using the software, to propose a possible direction of new software that supports their activities. To do this, we first surveyed sixty members of the OpenCreators, which is the largest 3D printing creator community in South Korea, about the 3D modelling Software that they use for their 3D printing creations, the best 3D modelling software for the 3D printing, and the type of frequently printing creation using the best 3D modelling software. We then analysed the response results. As a result, we found that most of 3D printing creators in South Korea use Rhino and 123D Design. More specifically, the Rhino was being widely used by the people in the 3D printing industry to print prototypes, samples, and mock-ups, while the 123D Design was being mainly used for general purposes such as educational tools, accessories, and home interior accessories. Therefore, we believe it is necessary to develop the software in two separated categories, i.e. for the business, like the Rhino, and for the beginners, and educational and personal purposes, like the 123D Design. Finally, we stressed and proposed the necessity to support individual creators by developing an industry-specific 3D modeling software.

• Bulletin of the Korean Space Science Society
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• 1995.10a
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• pp.16-16
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• 1995

• Journal of Korean Society for Geospatial Information Science
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• v.2 no.2 s.4
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• pp.99-108
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• 1994

In this thesis, we propose the 3D terrain modelling method for the better understanding of the geographic information. The process of 3D terrain medelling consists of three steps. The first step is to obtain real-world data from satellite images and stored in the form of DEM(Digital Elevation Model). The second one is to extract the meaningful data from DEM data based on LOD(Level Of Detail). And the third is to construct the 3D surface by TIN(Triangulated Irregular Network) with the extracted meaingful data. The proposed dynamic TIN reconstruction algorithm locally reconstruct the existed TIN model with the additional a new point. In this way, we can construct the TIN with the reduced time and can simulated 3D terrain model in real time.

• Journal of Korean Society for Geospatial Information Science
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• v.5 no.2 s.10
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• pp.77-85
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• 1997

Researches in the field of Computer Graphics and Geographical Information Systems(GIS) have extensively studied the method of photo-realistic landscape modelling, because it have become a commom requirement in applications such as flight simulators, mission rehearsal, and construction planning. A common approach to the display of terrain uses a Digital Elevation Model(DEM). DEM is an evenly spaced array of the terrain elevation data and can be obtained from stereo satellite data. With the DEM data, the process of 3D terrain modelling consists of three steps. The first step is to extract the meaningful data (such as peak, pit, passes...) from DEM data based on LOD(Level Of Detail) criteria. The second is to construct the 3D surface by TIN, which represents a surface as a set of non-overlapping continuous triangular facets of irregular size and shape. The third is a rendering of 3D terrain model. The goal of this research is a construction of 3D terrain with TIN. To do this, we are going to app]y Radial Sweep Algorithm. Radial Sweep Algorithm for generating TIN works quickly and efficiently. However, it does not solve the problem caused by the approximated nature of triangulated surface. To solve this problem, this research derive improved radial sweep algorithms with the optimal triangle definition.

• ETRI Journal
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• v.5 no.3
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• pp.9-15
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• 1983

This paper describes the applicable method of part stress analysis failure rate prediction for electronic components in the MIL-HDBK-217D. The part stress analysis method requires the great amount of detailed informations, such as operating temperature, operating environment, etc. This paper calculates the failure rate of electronic components using the computer program. The program was written by Fortran V and has four basic units as follows (1) Raw data file (2) Failure rate calculation (3) Reliability modelling(Series only) (4) New data file The Functions and structure of the program are illustrated.

• Proceedings of the Materials Research Society of Korea Conference
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• 2008.05a
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• pp.36.1-36.1
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• 2008

• Journal of Digital Contents Society
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• v.16 no.2
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• pp.189-196
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• 2015

The proposed cooperative 3D modelling system enables more efficient modeling works by improving current cooperation systems. Current 3D modeling tasks work on off-line and most of works are cooperation systems which communicate by files. These cooperation system cannot be interactive, occurs time delay while feedback and must have some programs which can read the files. This paper solves these problems using web that has the characteristics of network and proposes new cooperation system form. Using WebGL(Web Graphics Library) which is proposing technology in technical realization of Web 3D modeling, we make 3D objects in web browser and these objects can be manipulated by server-client communication. Therefore, if people use this system, they can use real time interaction and feedback. Also this system lowers a software installation necessity and can access everytime if web browser is installed.

• Earthquakes and Structures
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• v.6 no.1
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• pp.19-43
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• 2014

A risk assessment framework for evaluating building structures is implemented in this study. This framework allows considering sources of uncertainty both on structural capacity and seismic demand. In particular randomness on seismic load, incident angle, material properties, floor mass and structural damping are considered; in addition the choice of fibre modelling versus plastic hinge model is also considered as a source of uncertainty. The main objective of this work is to study the contribution of these sources of uncertainty on the fragilities of steel and steel-reinforced concrete composite 3D building structures. The fragility curves are expressed in the form of a two-parameter lognormal distribution where vertical statistics in conjunction with metaheuristic optimization are implemented for calculating the two parameters.

• International Journal of High-Rise Buildings
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• v.7 no.4
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• pp.343-362
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• 2018

A simplified spring connection modelling approach for steel flush endplate beam-to-column connections in fire has been developed to enable realistic behaviour of connections to be incorporated into full-scale frame analyses at elevated temperature. Due to its simplicity and reliability, the proposed approach permits full-scale high-temperature frame analysis to be conducted without high computational cost. The proposed simplified spring connection modelling approach has been used to investigate the influence of connection ductility (both axial and rotational) on frame behaviour in fire. 2D steel and 3D composite frames with a range of beam spans were modelled to aid the understanding of the differences in frame response in fire where the beam-to-column connections have different axial and rotational ductility assumptions. The modelling results highlight that adopting the conventional rigid or pinned connection assumptions does not permit the axial forces acting on the connections to be accurately predicted, since the axial ductility of the connection is completely neglected when the rotational ductility is either fully restrained or free. By accounting for realistic axial and rotational ductilities of beam-to-column connections, the frame response in fire can be predicted more accurately, which is advantageous in performance-based structural fire engineering design.