• The Journal of Advanced Prosthodontics
• /
• 제10권5호
• /
• pp.335-339
• /
• 2018

PURPOSE. The purpose of the present study was to compare scanning trueness and precision between an abutment impression and a stone model according to dental computer-aided design/computer-aided manufacturing (CAD/CAM) evaluation standards. MATERIALS AND METHODS. To evaluate trueness, the abutment impression and stone model were scanned to obtain the first 3-dimensional (3-D) stereolithography (STL) file. Next, the abutment impression or stone model was removed from the scanner and re-fixed on the table; scanning was then repeated so that 11 files were obtained for each scan type. To evaluate precision, the abutment impression or stone model was scanned to obtain the first 3-D STL file. Without moving it, scanning was performed 10 more times, so that 11 files were obtained for each scan type. By superimposing the first scanned STL file onto the other STL files one by one, 10 color-difference maps and reports were obtained; i.e., 10 experimental scans per type. The independent t-test was used to compare root mean square (RMS) data between the groups (${\alpha}=.05$). RESULTS. The $RMS{\pm}SD$ values of scanning trueness of the abutment impression and stone model were $22.4{\pm}4.4$ and $17.4{\pm}3.5{\mu}m$, respectively (P<.012). The $RMS{\pm}SD$ values of scanning precision of the abutment impression and stone model were $16.4{\pm}2.9$ and $14.6{\pm}1.6{\mu}m$, respectively (P=.108). CONCLUSION. There was a significant difference in scanning trueness between the abutment impression and stone model, as evaluated according to dental CAD/CAM standards. However, all scans showed high trueness and precision.

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

• 한국정보처리학회:학술대회논문집
• /
• 한국정보처리학회 2017년도 춘계학술발표대회
• /
• pp.966-969
• /
• 2017

3D프린터 기술의 발달로 인해 다가오는 3D프린터의 개인화 시대에 맞추어 개인이 자신이 원하는 출력물을 자유롭게 쉽게 디자인하여 물체를 출력할 수 있도록 도와주는 3D모델링 툴이다. 본 논문에서는 3D프린터 사용에 가장 일반적으로 사용되는 STL파일을 사용자가 별도의 변환과정없이 오브젝트를 바로 STL로 만들어 낼 수 있는 모델링 도구를 제시한다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 추계학술대회 논문집
• /
• pp.105-108
• /
• 1997

To reduce design period, demands for rapid prototyping system is increasing. Among the rapid prototyping system, as a concept modeler, 3D Printer appears before the footlights. In spite of short production time and convenience, 3D Printer causes post processing problem. And that is too slow to adapt to the demand of workshop. In this research, we developed a system for reducing build time and roughness using splitting operation. Also, propose BFS(B-rep For STL) data structure to maintain model data, split STL model and implement Euler Operation for input and output.

• 대한치과재료학회지
• /
• 제44권4호
• /
• pp.329-336
• /
• 2017

본 연구는 맞춤형 지대주 (custom abutment) 설계 시 CAD 프로그램 내에서 선택된 수렴 각 그리고 곡률 반경 값 사용에 따른 가공 정확도를 평가하고자 한다. 치과용 CAD를 기반으로 10개의 맞춤형 지대주를 설계하였다. 제작된 맞춤형 지대주를 정밀 접촉식 스캐너를 이용하여 한 개의 시편을 10회 반복 스캔하였다. 스캔 된 맞춤형 지대주의 데이터는 "Test STL" 파일로 지정하여 저장하였다. Geomagic studio 소프트웨어를 이용하여 각 "Test STL" 파일과 동명 번호로 지정하여 저장된 CAD-reference-model STL 파일 (CRM)과 중첩하였다. 실험 결과에서 A8 군(수렴 각 $8^{\circ}$) 군은 A4 군(수렴 각 $4^{\circ}$) 보다 낮은 오차 수치를 나타났다. 또한, 곡률 반경 값이 높을 수록 맞춤형 지대주의 Top 그리고 chamfer 부위에 오차가 적게 나타냈다(p< 0.05). 전체적으로, 맞춤형 지대주 설계 시 곡률 반경 값은 가공 정확도에 영향을 미치는 것을 알 수 있었다.

• 한국정밀공학회지
• /
• 제16권1호통권94호
• /
• pp.95-107
• /
• 1999

The design models of a new product in general are created using clay models or wooden mock-ups. The reverse engineering(RE) technology enables us to quickly create the CAD model of the new product by capturing the surface of the model using laser digitizers or coordinate measuring machines. Rapid prototyping (RP) is another technology that can reduce the product development time by fabricating the physical prototype of a part using a layered manufacturing technique. In reverse engineering process, however, the digitizer generates an enormous amount of point data, and it is time consuming and also inefficient to create surfaces out of these data. In addition, the surfacing operation takes a great deal of time and skill and becomes a bottleneck. In rapid prototyping, a faceted model called STL file has been the industry standard for providing the CAD input to RP machines. It approximates the CAD model of a part using many planar triangular patches and has drawbacks. A novel procedure that overcomes these problems and integrates RE with RP is proposed. Algorithms that drastically reduce the point clouds data have been developed. These methods will facilitate the use of reverse engineered geometric data for rapid prototyping, and thereby will contribute in reducing the product development time.

• 한국경영과학회:학술대회논문집
• /
• 대한산업공학회/한국경영과학회 2000년도 춘계공동학술대회 논문집
• /
• pp.724-727
• /
• 2000

Rapid Prototyping(RP)이란 3차원 솔리드 모델을 단면화한 뒤 하나씩 적층하는 가공방식을 총칭한다. 이때 단면화하는 방법에 따라서 uniform, adaptive slicing으로 나뉘며, 입력 모델에 따라서 direct slicing과 STL을 이용한 방식으로 나뉜다. 적층 방법에 따라서는 연속된 2D 윤곽을 기반으로 적층하는 vertical layer 방식과 인접한 두 개의 2D 윤곽들을 연결하며 만들어진 3D layer를 기반으로 가공하는 sloping layer방식으로 나뉠 수 있다. 현재 상용 RP 시스템들에서는 거의 모든 경우 vertical layer 방식이 채택되어 사용되고 있다. RP와 절삭 공정, 예를 들면 CNC 밀링의 장점을 효율적으로 결합하기 위해서는 임의의 복잡한 형상을 갖는 솔리드 모델을 정밀도에 제한이 없이 제조할 수 있어야 한다. 그러나 절삭 공정은 특별한 전문적 지식들을 필요로 한다 또한 상용 RP에서 사용하는 순차적인 적층 작업으로는 가공할 수 없는 형상들이 많다. 대표적인 것으로 지지대를 필요로 하는 형상들이 있다. 이러한 형상들을 지원하기 위해서는 복잡한 3D 형상을 절삭 가능한 형식으로 분할하는 것과 적층 가능한 순서대로 공정 계획하는 것이 필요하게 된다. 본 연구에서는 SDM에서 제시된 3D 분할 방법이 솔리드 모델을 기반으로 전개되어 STL file과 같은 삼각다면체 형식으로 근사화된 모델에 적용하기 어렵다는데 착안하여 STL file에서 읽어들인 삼각 다면체 모델을 가공 가능한 3D 형상으로 분할하는 알고리즘을 제시하고자 한다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1995년도 추계학술대회 논문집
• /
• pp.903-906
• /
• 1995

In this paper,human body models have been manufactured by the use of rapid prototyping techniques, which are to be used for surgery planning in clinical practice. In this manufactacturing process, CT or MRI data of human bodies are prepared and the images are processed to obtain sectional contours. With these contours, three-dimensional surface triangulated models are constructed, which finally transformed to STL file for rapid prototyping. For this purpose, total service system for manufacturing of human body models is constructed by employing commercial softwares, and the related problems and process parameters are investigated

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 1997년도 춘계학술대회 논문집
• /
• pp.321-326
• /
• 1997

This paper present how VRML file format can be used for RP Technology. VRML standards provids compact and powerful interface between remote RP manufacturer in network independent environment. We have constructed integrated and network-connected server system which can share the CAD data and varios process which is STL-to-VRML translater,slicing process,slice anchor process etc. This Server system consisted in file converter between STL and VRML,CGI system which sends a generated data to VRML client or browser, slice-generator which can re-slice at varied thickness and simulator which can show and check simultaneously status between near slices with support. This system aims to the integrated simulator which supports graphic animator and FEA analysis system.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2003년도 춘계학술대회 논문집
• /
• pp.441-447
• /
• 2003

In the study, we described on the 3D solid model be made on the AutoCAD haved an effect on the deviation of form as RP manufactures the facetres. The STL file improved the deviation of form as the facetres value but the deviation of form have the difference a little as the RP system. In result, we ruled the correlation with the 3D solid model and the RP sample manufacturing, with manufacture RP sample according to facetres value in complex shape. And we developed the program which recombination the STL file that we make use of the AutoLISP.