• 한국산업융합학회 논문집
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• 제5권2호
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• pp.141-146
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• 2002

Stereolithography is the best known as rapid prototyping system. It uses the STL format data which is generated from CAD system. In this study, One of the main function of this developed CAM system deals with shape modification which divide a shape into two parts or more. The cross section of a STL part by a z-level is composed with nested or single polygonal closed loop. In order to make RP product, closed loops must fill with triangular facets from SSET and recover sliced triangular facets which is located normal direction to the cross sectional plane. The system is development by using Visuall C++ compiler in the environment of pentium PC. Operating system is Windows NT workstaion from Micro-Soft.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.81-86
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• 1999

The STL file format is an approximation of 3-D model with triangular facets. STL is a standard input file format of Rapid Prototyping(RP) equipment. In computer graphics, a circle has been approximated with an inscribed polygon, which causes an error between the real and approximated circles. In this study, an intersecting polygon has been used to approximate the circle and applied to produce more accurate RP part. The newly proposed method shows it's excellence in part accuracy.

• 한국정밀공학회지
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• 제15권12호
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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.

• International Journal of Precision Engineering and Manufacturing
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• 제3권2호
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• pp.5-14
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• 2002

Internet becomes very common tool far communication and data sharing. Virtual readily(VR) on web browser, and virtual prototyping and virtual manufacturing is widely used in many engineering fields. The reduction of overall development process and error minimization during data conversion becomes very crucial where sharing data via Internet and VR. This paper deals with the advantage and disadvantage of VRML format used in RP(Rapid Prototyping), and a software for RP data preparation is developed. If VRML format as an international standard for VR, is replaced with STL format, the weak points of STL formal can be overcome and the technique related to virtual prototyping and virtual manufacturing can be addressed more systematically by sharing the data. The system developed in this work shows a good window to get access to a mare realistic observation of an object for an RP system from a long remote sites in a more systematic way.

• 한국멀티미디어학회논문지
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• 제5권5호
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• pp.552-561
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• 2002

본 논문은 쾌속조형(rapid prototyping) 시스템에서 사용되며 3D 기하학적 형상을 가지는 STL 파일에 워터마크를 삽입하고 추출하는 방법에 관한 연구이다. 제안된 알고리즘은 3D 형상의 왜곡이 없도록 하기위해, 패싯의 법선 영역과 꼭지점 영역에 워터마크를 삽입한다. 워터마크 비트들은 법선의 위치와 꼭지점의 순서 정보를 이용하여 삽입된다 제안된 알고리즘은 패싯의 저장 순서에 대한 종속성이 없으며, 워터마크의 비가시성 (invisibility)을 충족한다. 제안된 알고리즘으로 3D 기하학적 형상에 워터마크를 삽입하고 추출하는 실험 결과들은 STL로 표현된 3D원형상에 영향을 주지 않고 워터마크의 삽입과 추출이 가능함을 보여준다.

• 한국CDE학회논문집
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• 제11권6호
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• pp.440-446
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• 2006

This study relates to the effect of forming time of injection path on the total process. The whole process can be divided into build process of forming path of injection and after treatment process. The total time required for the whole process could be reduced by reducing the forming time of injection path using SLC file to correct the problems of STL file that is the basic file format for high speed molding devices. First of all, I verify the forming time of injection path according to the conditions of STL file during the formation of injection path. And I verify problems using STL file during formation of injection path. And then I tried to solve problems of STL file by comparing between the formation time of injection path and the existing method using SLC files.

• International Journal of CAD/CAM
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• 제2권1호
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• pp.55-67
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• 2002

In many areas of industry, it is desirable to have fast and reliable systems in order to quickly obtain suitable solid models for computer- aided analyses. Nevertheless it is well known that the data exchange process between CAD modelers and CAE packages can require significative efforts. This paper presents an approach for geometrical data exchange through triangulated boundary models. The proposed framework is founded on the use of STL file specification as neutral format file. This work is principally focused on data exchange among CAD modelers and FEA packages via STL. The proposed approach involves the definition of a topological structure suitable for the STL representation and the development of algorithms for topology and geometry data processing in order to get a solid model suitable for finite element analysis or other computer aided engineering purposes. Different algorithms for model processing are considered and their pros and cons are discussed. As a case study, a prototype modeler which supports an exporting filter for a commercial CAE package has been implemented.

• International Journal of Internet, Broadcasting and Communication
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• 제11권3호
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• pp.8-19
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• 2019

Since their emergence in 2007, smart phones have advanced up to the point that 5G mobile communication in 2019 started to be commercialized. Accordingly, now it is possible to share 3D modeling files and collaborate by means of a mobile web. As the recently commercialized 5G mobile communication network is so useful in sharing 3D modeling files and collaborating that even large-size geometry files can be transmitted at ultra high speed with ultra low transfer delay. We examines characteristics of major 3D file formats such as STL, OBJ, FBX, and glTF and compares the existing 4G LTE (Long Term Evolution) network with the 5G NR (New Radio) mobile communication network. The loading time and packets of each format were measured depending on the mobile web browser environments. We shows that in comparison with 4G LTE, the loading time of STL and OBJ file formats were reduced as much as 6.55 sec and 9.41 sec, respectively in the 5G NR and Chrome browsers. The glTF file format showed the most efficient performance in all of the 4G/5G mobile communication networks, Chrome, and Edge browsers. In the case of STL and OBJ, the traffic was relatively excessive in 5G NR and Edge browsers. The findings of this study are expected to be utilized to develop a 3D file format that reduces the loading time in a mobile web environment.

• 한국콘텐츠학회논문지
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• 제18권9호
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• pp.710-721
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• 2018

본 연구에서는 오픈소스 SW인 Blender를 사용하여 인터넷에서 쉽게 구할 수 있는 3D 프린터용 STL(stereolithography) 파일 기반의 3D 애니메이션을 제작하는 방법을 제시하고 이를 OBJ(Object) 파일과 FBX(filmbox) 파일을 이용하는 경우와 비교하였다. STL 파일은 무료로 제공되는 장점이 있지만 OBJ나 FBX 파일과는 달리 계층 구조(hierarchy), 머티리얼(material) 및 텍스쳐(texture) 정보를 포함하지 않기 때문에 3D 애니메이션 제작과정이 좀 더 복잡해진다. 특히 계층구조 정보의 누락은 3D 애니메이션의 핵심인 리깅(rigging) 작업 시에 원하지 않는 부위가 움직이는 심각한 문제를 발생시키는 원인이 된다. 본 연구에서는 Blender의 웨이트 페인팅 기능을 이용하여 계층구조 누락으로 인한 문제를 해결할 수 있음을 예증하였으며 샘플링 횟수와 해상도가 렌더링(rendering) 시간에 미치는 영향도 함께 조사하였다. 한편 3D 프린터로 출력한 곤충 모형은 초등과학교육에서 새로운 형태의 교육 자료로 활용이 가능할 것으로 기대된다.

• 한국CDE학회논문집
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• 제6권1호
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• pp.48-58
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• 2001

One of the biggest problems of rapid prototyping(RP) technologies lies in their standard file format for CAD data exchange. Current methods using the de facto industry standard 'STL'have at times resulted in problems such as accuracy, redundancy, and integrity. In this paper we propose a STEP based data exchange framework for rapid prototyping systems. In this paradigm of data exchange, STEP models can be imported and converted into faceted B-rep. solid models for visualization and 2-D layer data for RP. Also an STL model, on the other hand, can be converted into a faceted B-rep. STEP model and exported as a new data exchange model with RP information.