• Journal of Industrial Technology
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• v.18
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• pp.131-138
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• 1998

Numerical modeling for electromagnetic exploration methods are essential to understand behaviours of electromagnetic fields in complex subsurfaces. In this study, a finite element method was adopted as a numerical scheme for the 2.5-dimensional forward problem. And a finite element equation considering linear conductivity variation was proposed when 2.5-dimensional differential equation to couple eletric and magnetic field was implemented. Model parameters were investigated for near-field with large source effects and far-field with responses dominantly by homogeneous half-space. Numerical responses by this study were compared with analytic solutions in homogeneous half-space and compared with other three dimensional numerical results.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1463-1466
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• 2003

Korean tank has been used from the end of 1980's. Even though Korean tank is regarded as the tank which is made in Korea, a lot of parts still need to be imported from abroad. Therefore, the localization for the parts of Korean Tank is necessary to be set free from the rate of dependence on imports. In this research, one of the most important part of Korean Tank, Lever, was considered to carry out localization. For the first step, two dimensional drawing and three dimensional modeling of the Lever was done. Secondly, the stress analysis was carried out for Lever and it is shown that the predictions of the proposed modeling are in very good agreement with the expected results.

• Journal of Conservation Science
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• v.35 no.1
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• pp.71-80
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• 2019

This study examined the applicability of digital technologies based on three-dimensional(3D) scanning, modeling, and printing to the restoration of damaged artifacts. First, 3D close-range scanning was utilized to make a high-resolution polygon mesh model of a roof-end tile with a missing part, and a 3D virtual restoration of the missing part was conducted using a haptic interface. Furthermore, the virtual restoration model was printed out with a 3D printer using the material extrusion method and a PLA filament. Then, the additive structure of the printed output with a scanning electron microscope was observed and its shape accuracy was analyzed through 3D deviation analysis. It was discovered that the 3D printing output of the missing part has high dimensional accuracy and layer thickness, thus fitting extremely well with the fracture surface of the original roof-end tile. The convergence of digital virtual restoration based on 3D scanning and 3D printing technology has helped in minimizing contact with the artifact and broadening the choice of restoration materials significantly. In the future, if the efficiency of the virtual restoration modeling process is improved and the material stability of the printed output for the purpose of restoration is sufficiently verified, the usability of 3D digital technologies in cultural heritage restoration will increase.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.353-356
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• 2002

In vehicle accidents, the rolling, pitching, and yawing which are produced by collisions affect the motions of vehicle. Therefore, vehicle behavior under impact situation should be analyzed in three-dimension. In this study, three-dimensional vehicle dynamic equations based on impulse-momentum conservation principles under vehicle impact are introduced for simulation. This analysis has been performed by the real vehicle impact data from JARI and RICSAC. This study suggested each system modeling such as suspension, steering, brake and tire as well as the appropriate vehicle behavior simulation model with respect to pre and post impact.

• Journal of Welding and Joining
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• v.16 no.4
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• pp.109-116
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• 1998

The three-dimensional profile of a solder fillet is predicted by minimizing the surface tension and gravity energies of the solder joint using finite element modeling. Geometric complexity stemming from the inclined plane of the gullwing lead is resolved by employing three element types. These element types are used to describe the joint profile formed on the vertical, inclined and interfacial planes. The predicted solder joint profiles show good agreements with the experimental data provided that the solder volume is adjusted considering the wicking effects. Effects of the pad length, inclined lead angle and solder volume on joint profiles are also investigated.

• Korean Journal of Computational Design and Engineering
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• v.5 no.4
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• pp.293-300
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• 2000

The non-manifold geometric modeling technique is to improve design process and to Integrate design, analysis, and manufacturing by handling mixture of wireframe model, surface model, and solid model in a single data structure. For the non-manifold geometric modeling, Euler operators and other high level modeling methods are necessary. Boolean operation is one of the representative modeling method for the non-manifold geometric modeling. This thesis studies Boolean operations of non-manifold model with the data structure of selective storage. The data structure of selective storage is improved non-manifold data structure in that existing non-manifold data structures using ordered topological representation method always store non-manifold information even if edges and vortices are in the manifold situation. To implement Boolean operations for non-manifold model, intersection algorithm for topological cells of three different dimensions, merging and selection algorithm for three dimensional model, and Open Inventor(tm), a 3D toolkit from SGI, are used.

• Journal of Conservation Science
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• v.28 no.1
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• pp.87-94
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• 2012

This study was focused on digital restoration and surface depth modeling applying the three-dimensional laser scanning system of the Haeundae Stone Inscription. Firstly, the three-dimensional digital restoration carried out acquiring of point cloud using wide range and precision scanner, thereafter registering, merging, filtering, polygon mesh and surveyed map drawing. In particular, stroke of letters, inscribed depth and definition appearing the precision scanning polygon was outstanding compared with ones of the wide range polygon. The surface depth modeling completed through separation from polygon, establishment of datum axis, selection of datum point, contour mapping and polygon merging. Also, relative inscribed depth (5~17mm) and outline by the depth modeling was well-defined compared with photograph and polygon image of the inscription stone. The digital restoration technology merging wide range and precision scanning restored the total and detailed shape of the Stone Inscription quickly and accurately. In addition, the surface depth modeling visibly showed unclear parts from naked eye and photograph. In the future, various deteriorations and surrounding environment change of the Stone Inscription will be numerically analyze by periodic monitoring.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 1999.06a
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• pp.133-140
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• 1999

In this paper, we propose a method of image-based three-dimensional modeling for realistic facial expression. In the proposed method, real human facial images are used to deform a generic three-dimensional mesh model and the deformed model is animated to generate facial expression animation. First, we take several pictures of the same person from several view angles. Then we project a three-dimensional face model onto the plane of each facial image and match the projected model with each image. The results are combined to generate a deformed three-dimensional model. We use the feature-based image metamorphosis to match the projected models with images. We then create a synthetic image from the two-dimensional images of a specific person's face. This synthetic image is texture-mapped to the cylindrical projection of the three-dimensional model. We also propose a muscle-based animation technique to generate realistic facial expression animations. This method facilitates the control of the animation. lastly, we show the animation results of the six represenative facial expressions.

• Proceedings of the KSEEG Conference
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• 1999.04a
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• pp.74-76
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• 1999

• Journal of Korean Elementary Science Education
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• v.41 no.4
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• pp.673-689
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• 2022

To understand seasonal changes it is necessary to understand the relationship between celestial bodies in a three-dimensional space, and to this end, modeling activities in which students directly construct, use, evaluate, and modify three-dimensional models are important. In this study, the process of elementary school students using globes and light bulbs to model Earth's motion in a three-dimensional space as a cause of seasonal changes was analyzed. Seventeen sixth graders participated in the modeling process. After exploring phenomena and concepts related to seasonal change, students constructed models using globes and bulbs and used them to explain seasonal changes. Video data recording students' modeling process, students' activity sheets, and transcripts of post-interview were used as research data, and data triangulation was conducted. The modeling level analysis framework was also developed based on previous studies. In particular, the framework was developed in detail in this study in consideration of the concept of Earth's motion as well as understanding model and implementing modeling. In the final analysis framework, the 3D modeling level was classified from level 1 to level 3, and student performance that may appear at each level was specified. As a result of the study, there were two main levels of modeling using globes for elementary school students to explain seasonal changes. The rotation and tilt of the axis of rotation and revolution of the earth were considered but the level at which empirical evidence was not used (level 2), the level at which empirical evidence was used to explain seasonal chages (level 3). However, even when students use empirical evidence, it did not lead to the construction of a scientific model. In this study, the cause was explored in relation to the characteristics of the tool used for modeling.