• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.31 no.8
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• pp.27-35
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• 2003

Geometric modeling tool and analysis tool of shell surface have been developed in the different environments and purposes. Thus they cannot be naturally fitted to each other for the integrated design and analysis. In the present study, an integrated framework of geometric modeling, analysis， and design optimization is proposed. It is based on the common representation of B-spline surface patch. In the analysis module, a geometrically-exact shell finite element is implemented. In shape optimization module, control points of the surface are selected as design variables. For the computation of shape sensitivities, semi-analytical method is used. Sequential linear programming(SLP) is adopted for the shape optimization of surfaces. The developed integrated framework should serve as a powerful tool for the geometric modeling, analysis, and shape design of surfaces.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.5
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• pp.3-15
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• 2008

This study aims to simulate the 3 dimensional (3D) model of Keum-man connection canal using geographic information system (GIS) as well as considering design in viewpoint of engineering. The canal connects from Keumkang to Mangyungkang in order to supply fresh water into Saemankeum lake. This study used 3 dimensional spatial planning model (3DSPLAM) process to generate the 3D model, which has not only several planning layers in actual process, but also their corresponding layers in modeling process to simulate 3D space of rural villages. The discharge of the canal is $20m^3/s$ on slope of 1/28,400 in the canal length of 14.2km, which consists of pipe line and open channel. This study surveyed the route of the canal and its surrounding environment for facilities to make images in the 3D graphic model. Besides, the present study developed data set in GIS for geogrphical surface modeling as well as parameters in hydraulic analysis for water surface profile on the canal using HEC-RAS model. From the data set constructed, this study performed analysis of water surface profile with HEC-RAS, generation of digital elevation model (DEM) and 3D objects, design of the canal section and route on DEM in AutoCAD, and 3D canal model and its surrounding 3D space in 3DMAX with virtual reality. The study result showed that the process making 3D canal model tried in this study is very useful to generate computer graphic model with the designed canal on the surface of DEM. The generated 3D canal can be used to assist decision support for the canal policy.

• Smart Structures and Systems
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• v.26 no.3
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• pp.277-290
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• 2020

Disasters, including earthquakes and landslides, have enormous economic and social losses besides their impact on environmental disruption. Iran, and particularly its Western part, is known as an earthquake susceptible area due to numerous strong ground motions. Studying ecological changes due to climate change can improve the public and expert sector's awareness and response to future disastrous events. Synthetic Aperture Radar (SAR) data and Interferometric Synthetic Aperture Radar (InSAR) technologies are appropriate tools for modeling and surface deformation modeling. This paper proposes an efficient approach to detect ground deformation changes using Sentinel-1A. The focal point of this research is to map the ground surface deformation modeling is presented using InSAR technology over Sarpol-e Zahab on 25^th November 2018 as a study case. For surface deformation modeling and detection of the ground movement due to earthquake SARPROZ in MATLAB programming language is used and discussed. Results show that there is a general ground movement due to the Sarpol-e Zahab earthquake between -7 millimeter to +18 millimeter in the study area. This research verified previous researches on the advanced image analysis techniques employed for mapping ground movement, where InSAR provides a reliable tool for assisting engineers and the decision-maker in choosing proper policies in a time of disasters. Based on the result, 574 out of 682 damaged buildings and infrastructures due to the 2017 Sarpol-e Zahab earthquake have moved from -2 to +17 mm due to the 2018 earthquake with a magnitude of 6.3 Richter. Results show that mountainous areas have suffered land subsidence, where urban areas had land uplift.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.1
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• pp.33-39
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• 2022

As 3D printer-related patents expire and major technologies are disclosed, the price of 3D printers is dropping, creating an environment where you can easily find the product you want. In particular, the cheapest FDM (Fused Deposition Modeling) 3D printer is being used in various fields. The FDM method can be manufactured without collapsing of the shape only by attaching a support under certain conditions when outputting the shape. When printing a shape without a support, the irregular surface that occurs at a certain angle is a defect in the product, but it is considered that it can be used as another fun factor in terms of arts and crafts. In this paper, to obtain such an irregular surface, factors that can affect the output were controlled and only the output angle was tested as a displacement factor. As a result of the experiment, it was possible to obtain an irregular surface without the filament flowing down when printing at an angle of 62° to 70° from the vertical. Also, artificially irregular surfaces were applied to craft products.

• Journal of KIISE:Computer Systems and Theory
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• v.27 no.4
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• pp.353-361
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• 2000

In Computer Graphics, to select the element for modeling is very important in aspect of real-time processing of photorealistic images. Especially in modeling of informal objects, the criteria of choice are such as the minimum number of data, the easy rendering technique, and the expansibility. The metaball model which is one of the methods for modeling the implicit surface is excellent in modeling the complicated surface with a few data. However, a greater number of data are required for modeling objects that consist of planar surfaces with metaballs than with polygons. In this paper, we propose the new skeletal element, metacube which has the merits of metaball and improves the modeling ability of informal objects containing planar surfaces. A metacube has two parameters to change freely its shape from the cube to the sphere and can easily do the modeling of objects with curved surfaces and plane surfaces.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.957-960
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• 1995

A new method is introduced for the parametrization in B-spline surface interpolation. THis method uses the basis function to assign the parameter values to the arbitrary set of geometric data. This method gives us several important advantages in geometric modeling.

• Nuclear Engineering and Technology
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• v.31 no.2
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• pp.182-191
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• 1999

The sorption of UO$_{2}$$^{2+}$ onto goethite and kaolinite under various experimental conditions was successfully interpreted using surface complexation modeling (SCM). The SCM approach used in this work is the triple-layer model (TLM) in which weakly bonded ions are modeled as outer-sphere (ion-pair) complexes and strongly bonded ions as inner-sphere (surface coordination) complexes. The change of ionic strength did not affect the U(VI) sorption onto goethite, thus the formation of inner-sphere surface complexes, (FeO)$_2$UO$_2$ and (FeO)$_2$(UO$_2$)$_3$OH$_{5}$ was assumed to simulate the effects of ionic strength and goethite concentration. On the other hand, the U(VI) sorption onto kaolinite showed ionic strength dependence, thus the formation of AlO-UO$_{2}$$^{2+}$(outer-sphere complex) and SiO(UO$_2$)$_3$OH$_{5}$ (inner-sphere complex) was assumed to simulate the experimental data. In the presence of carbonates, the sorption of U(VI) onto kaolinite decreased in the weakly alkaline pH range. This was well simulated assuming the formation of a outer-sphere surface complex, A1OH$^{2+}$- (UO$_2$)$_2$CO$_3$OH$_3$. Since SCM approach uses thermodynamic data such as surface complexation constants, it is more predictive than empirical modeling approach in which conditional values such as partition coefficient are used. used.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.1
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• pp.33-39
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• 2007

This paper is aimed at the development of a software that predicts the surface temperature profiles of three-dimensional objects on the ground by considering the spectral solar radiation through the atmosphere. The spectral solar radiation through the atmosphere is modeled by using the well-known LOWTRAN7 code which analyzes the detailed spectral transmission characteristics by considering the atmospheric gas layers. In this paper, the transient temperature distribution over a cylinder is calculated by using the semi-implicit method. The spectral radiative surface properties such as the absorptivity and emissivity of the objects are used to model the effects of the solar irradiation and the surface emission. Both the detailed spectral modeling and the simple total modeling for the solar radiation absorption show fairly good agreement with each other by showing less than 3% difference in surface temperature.

• Geophysics and Geophysical Exploration
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• v.4 no.2
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• pp.34-44
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• 2001

Forward modeling by construction of synthetic data is usually practiced in a horizontal surface and a few subsurface structures. However, in-situ surveys often take place in such topographic changes that the corrupted field data always make it difficult to interpret the right signals. To examine the propagation characteristic of elastic waves on the irregular surface, a general mesh generation code for finite element method was modified to consider the topography. By implementing this algorithm, the time domain modeling was practiced in some models with surface topography such as mound, channel, etc. The synthetic data obtained by receivers placed on surface also agreed with the analytic solution. The snapshots showing the total wave-field revealed the propagation characteristic of the elastic waves through complex subsurface structures and helped to identify the signals on the time traces. The transmission of Rayleigh waves along the surface, compressive waves, and sheer waves was observed. Moreover, it turned out that the Rayleigh waves behave like a new source at the edge.

• Computers and Concrete
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• v.22 no.2
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• pp.167-182
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• 2018

The modeling of loss of bond between reinforcing bars (rebars) and concrete due to corrosion is useful in studying the behavior and prediction of residual load bearing capacity of corroded reinforced concrete (RC) members. In the present work, first the possibility of using different methods to simulate the rebars-concrete bonding, which is used in three-dimensional (3D) finite element (FE) modeling of corroded RC beams, was explored. The cohesive surface interaction method was found to be most suitable for simulating the bond between rebars and concrete. Secondly, using the cohesive surface interaction approach, the 3D FE modeling of the behavior of non-corroded and corroded RC beams was carried out in an ABAQUS environment. Experimental data, reported in literature, were used to validate the models. Then using the developed models, a parametric study was conducted to examine the effects of some parameters, such as degree and location of the corrosion, on the behavior and residual capacity of the corroded beams. The results obtained from the parametric analysis using the developed model showed that corrosion in top compression rebars has very small effect on the flexural behaviors of beams with small flexural reinforcement ratio that is less than the maximum ratio specified in ACI-318-14 (singly RC beam). In addition, the reduction of steel yield strength in tension reinforcement due to corrosion is the main source of reducing the load bearing capacity of corroded RC beams. The most critical corrosion-induced damage is the complete loss of bond between rebars and the concrete as it causes sudden failure and the beam acts as un-reinforced beam.