• Journal of the Korean Society for Precision Engineering
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• v.29 no.1
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• pp.33-40
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• 2012

The scaffold serves as 3D substrate for the cells adhesion and mechanical support for the newly grown tissue by maintaining the 3D structure for the regeneration of tissue and organ. In this paper, we proposed integrated scaffold fabrication system using multi-axis rapid prototyping (RP) technology. It can fabricate various types of scaffolds: arbitrary sculptured shape, primitive shape, and tube shape scaffolds by layered dispensing biocompatible/ biodegradable polymer strands in designated patterns. In order to fabricate the 3D scaffold, we need to generate the plotting path way for the scaffold fabrication system. We design a data processing program - scaffold plotting software, which can convert the 3D STL file, primitive and tube model images into the NC code for the system. Finally, we fabricated the customized 3D scaffolds with high accuracy using the plotting software and the fabrication system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.536-539
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• 2002

The reverse engineering (RE) technology can quickly generate 3D point cloud data of an object by capturing the surface of a model using a 3D scanner. In the rapid prototyping (RP) technology, prototypes are rapidly produced from 3D CAD models in a layer-by-layer additive basis. In this paper, a physical human head shape is duplicated using a new RP process, the Transfer-type Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-ST), after the point cloud data of a human head shape measured from 3D SNX scanner are converted to STL file. From the duplicated human head shape, it has been shown that the VLM-ST process in connection with the 3D scanner is a fast and efficient process in that shapes with free surface, such as the human head shape, can be duplicated with ease. Considering the measurement time and the shape duplication time, the use of 3D SNX scanner and the VLM-ST process is expected to reduce the lead-time fur the development of new products in comparison with the other existing RE-RP connected manufacturing systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.24-27
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• 2001

Nowadays, increasing demand of the customized products has led to an increased usage of rapid prototyping in the product development. However, the acquisition price of a rapid prototyping equipment is still too high that not every body can afford to buy one. To offer a wide access to the users who need physical prototypes, a connection of the rapid prototyping equipment to the Internet is a viable step. It would allow a large group of customers all over the world to use the manufacturing capability of a service provider offering this kind of manufacturing service. To realize how such an e-manufacturing concept can look like, a LOM-type 3D printer developed at KIST has been used as test site and connected to the Internet. A possible user can log on to the server of the equipment and view his STL file and start the building operation from a remote place. To see whether the operation runs properly, a CCD camera is used to transmit the actual state of operation online. The result so far proves the feasibility of rapid prototyping on the Internet as well as an order-adaptive manufacturing system via web.

• Korean Journal of Computational Design and Engineering
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• v.5 no.2
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• pp.144-154
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• 2000

We propose an algorithm for obtaining a triangular approximation of a trimmed NLRBS surface. Triangular approximation is used in the pre-processing step of many applications such as RP(Rapid Prototyping), NC(Numerical Control) and FEA(Finite Element Analysis), etc. The algorithm minimizes the number of triangular elements within tolerance and generates a valid triangular mesh for STL file and NC tool path generation. In the algorithm, a subdivision method is used. Since a patch is a basic element of triangular mesh creation, boundary curves of a patch are divided into line segments and the division of curves is applied for the interior of the surface. That is, boundary curves are subdivided into line segments and two end points of each line segment are propagated to the interior of the surface. For the case of a trimmed surface, triangulation is carried out using a model space information. The algorithm is superior because the number of elements can be controlled as the curvature of the surface varies and it generates the triangular mesh in a trimmed region efficiently. To verify the efficiency, the algorithm was implemented and tested for several 3D objects bounded by NURBS surfaces.

• International Journal of CAD/CAM
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• v.6 no.1
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• pp.183-192
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• 2006

A CAD/CAM system has been developed for rapid prototyping (RP) of microfluidic devices based on excimer laser micromachining. The system comprises of two complementary softwares. One, the CAM tool, creates part programs from CAD models. The other, the Simulator Tool, uses a part program to generate the laser tool path and the 2D and 3D graphical representation of the machined microstructure. The CAM tool's algorithms use the 3D geometry of a microstructure, defined as an STL file exported from a CAD system, and process parameters (laser fluence, pulse repetition frequency, number of shots per area, wall angle), to automatically generate Numerical Control (NC) part programs for the machine controller. The performance of the system has been verified and demonstrated by machining a particle transportation device. The CAM tool simplifies part programming and replaces the tedious trial-and-error approach to creating programs. The simulator tool accepts manual or computer generated part programs, and displays the tool path and the machined structure. This enables error checking and editing of the program before machining, and development of programs for complex microstructures. Combined, the tools provide a user-friendly CAD/CAM system environment for rapid prototyping of microfluidic devices.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.168-177
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• 2001

Reverse engineering has been widely used for the shape reconstruction of an object without CAD data and the measurement of clay or wood models fur the development of new products. To generate a surface from measured points by a laser scanner, typical steps include the scanning of a clay or wood model, the generation of compatible input curves, the generation of a surface and manufacturing data like G code or STL file. A laser scanner has a great potential to get geometrical data of a model for its frost measuring speed and higher precision. The data from a laser scanner are composed of many line stripes of points including small spikes and noise. A new approach using automated surface generating algorithm is introduced to deal with problems during reverse engineering process. And the input data and the generated surface are represented in IGES format, thus can be supplied to other CAD/CAM software without any data manipulation.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.878-881
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• 2005

A Stereolithography technology is based on stacking of sliced layer from STL file that is converted from 3-dimensional CAD data. A microstereolithography technology is evolved from conventional stereolithography to fabricate microstructures. In this technology, we have to consider influence of resin flow to make refresh surface. To generate new resin surface, stage has to be moved downward deeply and upward to desired position. At this time, resin flow affects to refresh surface of resin. And resin viscosity is the key factor in simulation of resin flow. By setting optimal refresh time for resin surface, total fabrication time is reduced and there is no damage to fabricated layers. In this research, we simulate resin flow using CFD software and derive optimal stage moving time and dwelling time.

• Journal of the Korean Society of Radiology
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• v.11 no.5
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• pp.371-377
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• 2017

General phantom for practical X-ray photography Practical phantom is an indispensable textbook for radiology, but it is difficult for existing commercially available phantom to be equipped with various kinds of phantom because it is an expensive import. Using 3D printing technology, I would like to make the general phantom for practical X-ray photography less expensive and easier. We would like to use a skeleton model that was produced based on CT image data using a 3D printer of FDM (Fused Deposition Modeling) method as a phantom for general X-ray imaging. 3D slicer 4.7.0 program is used to convert CT DICOM image data into STL file, convert it to G-code conversion process, output it to 3D printer, and create skeleton model. The phantom of the completed phantom was photographed by X - ray and CT, and compared with actual medical images and phantoms on the market, there was a detailed difference between actual medical images and bone density, but it could be utilized as a practical phantom. 3D phonemes that can be used for general X-ray practice can be manufactured at low cost by utilizing 3D printers which are low cost and distributed and free 3D slicer program for research. According to the future diversification and research of 3D printing technology, it will be possible to apply to various fields such as health education and medical service.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.558-565
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• 2016

Recent 3D printing technology has been grafting onto various medical practices. In light of this trend, this research is intended to examine the figuration surface's accuracy of 3D images made by using DICOM images after printing by 3D printing. The medical images were obtained from animal bone objects, while the objects were printed after undergoing STL file conversion for 3D printing purposes. Ultimately, after the 3D figuration, which was obtained by the original animal bones and 3D printing, was scanned by 3D scanner, 3D modeling was merged each other and the differences were compared. The result analysis was conducted by visual figuration comparison, color comparison of modeling's scale value, and numerical figuration comparison. The shape surface was not visually distinguished; the numerical figuration comparison was made from the values measured from the four different points on the X, Y and Z coordinates. The shape surface of the merged modeling was smaller than the original object (the animal bone) by average of -0.49 mm in the 3D printed figuration. However, not all of the shape surface was uniformly reduced in size and the differences was within range of -0.83 mm on the experiment.

• Communications of Mathematical Education
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• v.29 no.1
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• pp.35-49
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• 2015

3D-Printing is one of the most innovative technologies that will be widely used in the 21st century. 3D-Printing also serves as an indispensable tool in STEAM education. In this article, we introduce what we have done in our mathematical modeling class in Uni. and recent R&E project under the support of Korean Foundation for the Advancement of Science and Creativity. We planned a model of STEAM education originating from our wish to make tangible models that use mathematical formulas to express the natural beauty of an object. We used a free, open-source software, Sage, to simulate these models online. Then, we created a program that generates a .STL file from these 3D images. This model can help students understand the natural beauty inherent in mathematics and use formulas and technology tools to simulate models in 3D. Finally, we were able to help students to create their own. STL files through a website we developed by adding Sage code into a Sage notebook. Then students can make and hold a 3D object of their very own. This process shows the possibility that mathematics, art and 3D-Printing can be effectively used to achieve the goals of STEAM education.