• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.578-582
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• 1996

Verification of STL is essential in RP. In the study, triangle based non-manifold geometric modeling that can check intersection between triangles was used to vilify STL. The method proposed in this study can be applied at the most general case and very useful, but has a penalty on computing thime of O(n$^2$)

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.6 no.1
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• pp.51-58
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• 1997

The verification of the STL file is essential to build the confident parts using a RP machine, because the STL file obtained from the CAD software has many errors-the orientation of triangle does not coincide with adjacent triangles or some triangles are omitted, overlpped and so forth. Especially, the STL file translated from the surface model has more errors than those translated from the solid model. In this study, all possible errors were classified with the most general from and the causes of errors were analyzed to verify and correct errors. Using the triangle based non-manifold geometric modeling, these errors were corrected. Especially, this study took the notice of the problem about the intersected triangles and non-manifold properties overlooked in the previous studies. But this study has a penalty on computing time of $O(n^2)$.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.10
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• pp.46-55
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• 1996

As industrial standard data, the STL format which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system in recent days. Because most RP system take the only form of two dimensional line segments as an input stream inspite of its imperfectness while converting into STL format, a CAD model is converted into a standard industrial format which is composed of many triangular facets. The error verifying process is composed of four main steps, and these are 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to anedge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Correct the wrong direction and normal vectors. This paper is concerned with serching the mentioned errors in advance and modifying them.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.04a
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• pp.597-601
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• 1996

Nowadays, the STL format, industrial standard data, which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system. Because most RP machine is accpted to only two dimensional line segments, but some STL translators are sometimes poorly implemented. The error verifying process is as follows. 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to an edge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Repair wrong direction and value of normal vectors. This paper is concerned with searching the mentioned errors in advance and modifying them.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.2
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• pp.103-109
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• 2017

Metal 3D printing, which is an additive metal manufacturing (AMM) process, enables the development of full-density metallic tools and parts using metal powders that are precisely delivered and controlled for deposition with no powder bed. However, some unknown geometric defects and irregular geometric features on an STL model can possibly result in incorrect metal part fabrication after the build. This study first proposes a methodical approach for verifying the build part, including the missing facet problems in an STL model, by defining some irregular features that possibly exist on the part. Second, 2D tool paths on each build layer were investigated for detecting any singular region inside the layer. The method was implemented for building two sample STL models using a direct energy deposition process, and finally, it was visually simulated for diagnosis.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.06a
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• pp.3-7
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• 2001

본 연구에서는 다종재료를 가공할 수 있는 RP(Rapid Prototyping)인 CAFL$^{VM}$의 구현을 위해 반드시 필요한 단면정보 추출기에 대하여 연구하였다. STL 3D 모형에서 단면정보를 추출하기 위해서, 패싯(facet)과 슬라이싱(slicing) 평면이 가질 수 있는 모든 경우를 고려한 알고리즘을 개발하였다. STL 파일의 구조적인 문제점 때문에 모호성과 처리량 증가 문제가 발생하지만, 본 연구에서는 창조 버퍼를 사용하여 이러한 문제점들을 효과적으로 해결하였으며, 이를 많은 STL 3D 샘플로 검증하였다.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.06a
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• pp.307-311
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• 2001

신속조형시스템(RP : Rapid Prototyping)용 자료교환 표준인 STL의 자료구조는 단순하고, 조형용 2차원 단면 자료로의 전환이 용이하며, 생산 가공 기술로서의 현대적인 특성(신속성, 조형성, 경제성, 청정성 등)을 가지고 이는 장점이 있는 반면에, STL 3D 좌표값의 기준(좌표계의 원점)이 되는 크기 정보가 없다. 이런 문제를 구현된 STL 뷰어에서는, 스케일링(scaling) 기법과 선형적인 이동 기법을 사용하여 해결하였고, CAD 시스템으로 제작된 파일 자체의 문제점 패싯(facet) 중복, 정밀도, 법선 벡터 값의 오류 등도 검증기(verifier)와 오류 정정기(error corrector)글 구현하여 해결하였다. 제안된 방법으로 구현된 STL 뷰어는 시스템의 안정성과 확장성, 그리고 효율성 측면에서 우수한 성능을 보였으며, 슬라이싱(slicing), 경로 추적기(path tracer)의 전처리기의 역할을 한다.

• Journal of Sensor Science and Technology
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• v.11 no.5
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• pp.263-272
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• 2002

In this paper, we investigate the potential for retrieval of morphometric data from three dimensional images of conducting bronchus obtained by X-ray Computerized Tomography (CT) and to explore the potential for the use of rapid prototype machine to produce physical hollow bronchus casts for mathematical modeling and experimental verification of particle deposition models. We segment the bronchus of lung by mathematical morphology method from obtained images by CT. The surface data representing volumetric bronchus data in three dimensions are converted to STL(streolithography) file and three dimensional solid model is created by using input STL file and rapid prototype machine. Two physical hollow cast models are created from the CT images of bronchial tree phantom and living human bronchus. We evaluate the usefulness of the rapid prototype model of bronchial tree by comparing diameters of the cross sectional area bronchus segments of the original CT images and the rapid prototyping-derived models imaged by X-ray CT.

• Proceedings of the KIEE Conference
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• summer
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• pp.845-847
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• 2004

단락시험시 시험회로의 주요 파라미터들은 시험전압과 시험전류를 이용하여 결정된다. 특히, 단락전류의 경우 전류파형의 피크치, RMS, 시간, DC-성분, 역률 등을 분석프로그램을 이용하여 분석하게 된다. 그러나 이러한 분석프로그램은 각 시험기관마다 다르고, 현재까지 분석프로그램을 검증할 국제저인 기준이 존재하지 않았다. 그러나 최근 들어 STL(Short-circuit Testing Liason)에서는 각 시험기관마다 상이한 분석프로그램을 검증할 절차에 대한 연구를 수행하여 왔으며 그 첫 번째로 단락전류 분석프로그램에 대한 성능 평가 절차가 어느 정도 완성되었다. 이에 본 논문에서는 STL에서 배포한 TDG(Test Data Generator)를 이용해reference curve를 생성하고, 전기연구원의 전류분석프로그램을 사용하여 분석프로그램의 신뢰성을 평가하여 보았다.

• Tunnel and Underground Space
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• v.27 no.2
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• pp.69-76
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• 2017

Physical models of underground mines are very useful to the design of mine openings and the management of work progress of mining companies as well as to consulting. Even though 3D image realization techniques for mine openings have already been developed by various companies the physical models are still widely used because they can provide better understanding without sophisticated equipments for the most of people. Conventional materials for the physical models are paper and acryl which demand a lot of time and labor to make the model even with low precision and high cost. In this research, 3D printing technique is adopted to develop the physical model with relatively short time, low cost, and proper degree of precision. Finally the computer software "UMine2STL" was developed and verified by comparing the printed product with its design.