• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.194-201
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• 2005

Recently, as Rapid Prototyping is attracting people's attention, many peoples are actively participating in the research on STL format. The STL files are transformed to be input for RP after modeling in CAD system. When the shape, however, needs to be changed or edited, it is impossible without the original data. So, if the original data is lost, new modeling is required. Therefore, this study suggests a way to edit the shape in STL format and to make the Boolean operation possible between the original and edited shapes. In addition, the reliability was confirmed after going over the errors of the edited data.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.12
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• pp.21-27
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• 1998

This paper recommends the database construction for STL data and the new method of Delaunay's triangulation method in order to decrease volume errors by verifying STL file errors and modifying hole errors. Each vertex for the boundary coordinates of the verified hole errors was analyzed according to the following cases: planes or slow curves, edges, apexes, and rapid curves. In each case, a different modification process was adopted. With this method, most errors resulting from the conversion into the STL data as well as lots of volume errors arising from error modification were decreased.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.965-969
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• 1995

This paper deals with effective using the IGES file for flexible data exchange among the other CAD/CAM system. If a data exchange between STL file and the neutral IGES file in Stereolithography system is available, a product design becomes more flexible. THere can be many restrictions and difficulties intranslating these data. First, an STL file follows two rules, such as right-hand rule, and vertex-to-vertex rule, thus requires a structural verification. Second, translation should be performed with minmal errors. It becomes very important to translate IGES file of limited kinds of entities fot the purpose of geometric information into STL file with minor data manipulation. The developed system suggests a good approach of translating the sampled B-spline surface of IGES and shows a potential linkage between IGES and STL format file.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.04a
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• pp.416-421
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• 1997

This study presents a way to construct 3D shape in STL format from 2D slice data. Nowadays ahape reconstruct has been done in many ares, the application of this method is important especially in Reverse Engineering which reconstructs original shape from cross-section data. Current RP (Rapid Prototyping) is used not only for the verification of a part designed but also for the production and tooling in more effective way. In RP technology, data should be prepared in STL format. In this paper, the way to make 3D shape data in STL format form 2D slice data is described which can be used to reconstruct an original shape in RP equipment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.3
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• pp.78-86
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• 2018

The 3D mesh model is used in various fields, such as virtual reality, shape-based searching, 3D simulation, reverse engineering, 3D printing, and laser scanning. There are various formats for the 3D mesh model, but STL and OBJ are the most typical. Since application systems support different 3D mesh formats, developing technology for converting 3D mesh models from one format into another is necessary to ensure data interoperability among systems. In this paper, we propose a method to convert a 3D mesh model in STL format into the OBJ format. We performed the basic design of the conversion system and developed a prototype, then verified the proposed method by experimentally converting an STL file into an OBJ file for test cases using this prototype.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.04a
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• pp.92-92
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• 2019

In this study, we evaluated the effect of branch (STB) and leave (STL) extracts from Sageretia thea on ${\beta}$-catenin level in human colorecal cancer cells, SW480 and lung cancer cells, A549. STB and STL dose-dependently suppressed the growth of SW480 and A549 cells. STB and STL decreased ${\beta}$-catenin level in both protein and mRNA level. MG132 decreased the downregulation of ${\beta}$-catenin protein level induced by STB and STL. However, the inhibition of $GSK3{\beta}$ by LiCl or ROS scavenging by NAC did not block the reduction of ${\beta}$-catenin protein by STB and STL. Our results suggested that STB and STL may downregulate ${\beta}$-catenin protein level independent on $GSK3{\beta}$ and ROS. Based on these findings, STB and STL may be a potential candidate for the development of chemopreventive or therapeutic agents for human colorectal cancer and lung cancer.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.11
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• pp.140-147
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• 1995

This paper deals with conversion from the STL file to the Slice to the Slice cross-sectional information for Stereolithography. The STL file is widely used for Stereolithography, but it is very difficult to convert STL file into Slice file directly. Because it consists of an ordered list of triangular net without any topological information other than the orientation of each facet. So, The system is accomplished by data flow through several intermediate stages such as Reference. SL1. .SL2L. .SL3. and .SLC file. The data processing is performed in 5 steps: 1) Create a Reference file including common information. 2) Modify STL file within the effective range of SL machine. 3) Calculate a point of intersection between plane equation and line equation. 4) Sort z values in ascending order using quick sort algorithm. 5) Search the adjacent points and formulate a closed loop usingsingly linked linear list. The system is developed by using Borland C++ 3.1 compiler in the environment of Pentium PC, and verified to be satisfactory by making some prototypes of electric household appliances.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.10a
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• pp.889-893
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• 1995

This paper verified error of STL file and presented a new application of reformed division method for reducing to appeared error by using Delaunay triangulation method that used to modify error of verified data. First, it is analyzed each vertices in hole error and classified follow case that is 1. case of plan or slope, 2. case of edge, 3. case of apex and 4. case of rapid curve, and reduced volume tolerance between original model and converted model after convert STL file.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.997-999
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• 2015

SketchUP은 최근 인기를 얻고 있는 3D 모델링 도구지만, 3D 프린터용 표준 파일 포맷인 STL을 지원하지 않는 단점이 있다. 본 논문에서는 SketchUp에서 만든 3D 모델(FBX)을 불러 와서 사용하고, STL로 변환할 수 있는 프로그램을 구현하는 방법을 논한다.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.710-721
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• 2018

In this study, we have suggested a method to create 3D animation based on STL files which are easily available on the internet using Blender, which is one of the most popular open-source 3D modeling SW. And the procedure of making 3D animation using STL file was compared with those for OBJ or FBX files as well. Contrary to OBJ and FBX, STL files do not contain information regarding hierarchy, material and texture which are very important in making 3D animation. Especially the absence of hierarchy may cause serious problems in rigging, which involves movement of unwanted parts of 3D object during rigging process. It is demonstrated that the weight painting feature of Blender could be a solution to tackle the faulty rigging due to attributes of STL files. The effect of the sampling frequency and the resolution on the rendering time is also investigated with respect to the 3D mantis animation. It is also seen that insect models by 3D printer could be used as a new type of pedagogical material in the elementary science education.