• International Journal of CAD/CAM
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• 제7권1호
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• pp.81-89
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• 2007

As the modular production is an important issue in globalized manufacturing industries, sub modules or parts of the final product are provided by many suppliers. Some part suppliers design their own products for themselves. In some cases, part supplier may provide the same type product to multiple 1-tier companies. Because all suppliers and 1-tier companies can not use the same CAD system in general case, the engineering change in the CAD model of one company could not propagate to related CAD models of other companies directly. Although they use the same CAD system, it is hard to share their CAD model with each other because of company security policy. In this paper, the neutral reference model, which consists of the neutral skeleton model and the external reference model, is proposed to apply a global top-down modeling approach to collaborating companies.

• 한국CDE학회논문집
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• 제13권4호
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• pp.243-254
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• 2008

As modular production becoming increasingly widespread in globalized manufacturing industries, sub modules or parts of the final product are being provided by many suppliers. Some part suppliers design their own products for themselves. In some cases, part suppliers provide the same type of product to multiple OEM companies. Because all part suppliers and OEM companies typically cannot use the same CAD system, engineering change in the CAD model of one company cannot be directly propagated to related CAD models of other companies. Even if two companies use the same CAD system, it may be difficult to share their CAD model owing to corporate security policy. In this paper, a neutral reference model that consists of a neutral skeleton model and an external reference data model is proposed as a new medium for the sharing and propagation of engineering change information among collaborating companies.

• The Journal of Advanced Prosthodontics
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• 제10권3호
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• pp.245-251
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• 2018

PURPOSE. To evaluate the accuracy of a model made using the computer-aided design/computer-aided manufacture (CAD/CAM) milling method and 3D printing method and to confirm its applicability as a work model for dental prosthesis production. MATERIALS AND METHODS. First, a natural tooth model (ANA-4, Frasaco, Germany) was scanned using an oral scanner. The obtained scan data were then used as a CAD reference model (CRM), to produce a total of 10 models each, either using the milling method or the 3D printing method. The 20 models were then scanned using a desktop scanner and the CAD test model was formed. The accuracy of the two groups was compared using dedicated software to calculate the root mean square (RMS) value after superimposing CRM and CAD test model (CTM). RESULTS. The RMS value ($152{\pm}52{\mu}m$) of the model manufactured by the milling method was significantly higher than the RMS value ($52{\pm}9{\mu}m$) of the model produced by the 3D printing method. CONCLUSION. The accuracy of the 3D printing method is superior to that of the milling method, but at present, both methods are limited in their application as a work model for prosthesis manufacture.

• 한국CDE학회논문집
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• 제16권1호
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• pp.21-30
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• 2011

Similarity assessment of a CAD model is one of important issues from the aspect of model re-using. In real practice, many new mechanical parts are designed by modifying existing ones. The reuse of part enables to save design time and efforts for the designers. Design time would be further reduced if there were an efficient way to search for existing similar designs. This paper proposes an efficient algorithm of similarity assessment for mechanical part model with design history embedded within the CAD model. Since it is possible to retrieve the design history and detailed-feature information using CAD API, we can obtain an accurate and reliable assessment result. For our purpose, our assessment algorithm can be divided by two: (1) we select suitable parts by comparing MSG (Model Signature Graph) extracted from a base feature of the required model; (2) detailed-features' similarities are assessed with their own attributes and reference structures. In addition, we also propose a indexing method for managing a model database in the last part of this article.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2009년도 추계학술대회
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• pp.204-207
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• 2009

본 논문은 마커리스 증강현실(Markerless Augmented Reality)의 구현과 레퍼런스(reference) 데이터 그룹을 효율적으로 생성하고 활용하는 방법을 제안한다. 구현은 카메라 설정과 레퍼런스 데이터 그룹 생성, 트래킹(tracking) 부분으로 되어 있다. 효율적인 레퍼런스 데이터 그룹을 생성하기 위해서는 CAD모델과 같은 3D모델을 필요하며, 다양한 관점에서 본 레퍼런스 데이터 그룹을 생성해야 한다. 모델에 대한 영상에서 특징점들을 추출하고, 광선 추적법을 이용하여 그 특징점에 대응하는 3D좌표를 추출하여, 모델의 특징점 들에 대한 2D/3D 대응점의 레퍼런스 데이터 그룹이 구성된다. 트래킹 할 때 현재 프레임영상에서 특징점 들이 가장 많이 매칭되는 레퍼런스 데이터와 그 주위의 모델 데이터만을 이용하기 때문에 빠르게 트래킹 할 수 있다.

• Journal of Computational Design and Engineering
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• 제2권4호
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• pp.253-260
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• 2015

Feature-based NC machining, which requires high quality of 3D CAD model, is widely used in machining aircraft structural part. However, there has been little research on how to automatically detect the CAD model errors. As a result, the user has to manually check the errors with great effort before NC programming. This paper proposes an automatic CAD model errors detection approach for aircraft structural part. First, the base faces are identified based on the reference directions corresponding to machining coordinate systems. Then, the CAD models are partitioned into multiple local regions based on the base faces. Finally, the CAD model error types are evaluated based on the heuristic rules. A prototype system based on CATIA has been developed to verify the effectiveness of the proposed approach.

• 한국정보통신학회논문지
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• 제13권11호
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• pp.2335-2340
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• 2009

본 논문은 레퍼런스(reference) 데이터 그룹을 효율적으로 생성하고 활용한 마커리스 증강현실(Markerless Augmented Reality)의 구현 방법을 제안한다. 카메라 설정과 레퍼런스 데이터 그룹 생성, 트래킹 (tracking) 부분으로 되어 있다. 효율적인 레퍼런스 데이터 그룹을 생성하기 위해서는 CAD모델과 같은 3D모델을 필요하며, 다양한 관점에서 본 레퍼런스 데이터 그룹을 생성해야 한다. 모델에 대한 영상에서 특징점들을 추출하고, 광선 추적법을 이용하여 그 특징점에 대응하는 3D좌표를 추출하여, 모델의 특징점들에 대한 2D/3D 대응접의 레퍼런스 데이터 그룹이 구성된다. 트래킹 할 때 현재 프레임영상에서 특징점 들이 가장 많이 매칭되는 레퍼런스 데이터와 그 주위의 모델 데이터만을 이용하기 때문에 빠르게 트래킹할 수 있다.

• 한국CDE학회논문집
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• 제7권3호
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• pp.148-156
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• 2002

Most Rapid Prototyping (RP) processes adopt a solid Computer Aided Design (CAD) model, which will be sliced into thin layers of constant thickness in the building direction. Each cross-sectional layer is successively deposited and, simultaneously, bonded onto the previous layer; and eventually the stacked layers from a physical part of the model. A new RP process, the transfer-type Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-ST), has been developed to reduce building time and to improve the surface finish of parts with the thick layers and a sloping surface. This paper describes the generation of Unit Shape Layer (USL), the cutting path data of the linen. hotwire cutter for the VLM-ST process. USL is a three-dimensional layer with a thickness of more than 1 mm and a side slope, and it is the basic unit of cutting and building in the VLM-ST process. USL includes data such as layer thickness, positional coordinates, side angles of each layer, hotwire cutting speed, the heat input to the hotwire, and reference shape. The procedure of generating USL is as follows: (1)Generation of the mid-slice from the CAD model, (2)Conversion of the mid-slice into a simply connected domain, (3)Generation to the reference shape for the mid-slice, (4)Calculation of the rotation angle of the hotwire of the cutting system.

• 대한기계학회논문집A
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• 제20권11호
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• pp.3525-3537
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• 1996

This paper presents a CAD program develpoed on a microcomputer in order to support graphic and computational assessment of ergonomic problems associated with the design of a man-in-cab system. The program is coded to help workspace designers with ergonomic evaluations needed in the design stage. This paper proposed a biomechanical -ergonomic evaluations needed using man and workplace models. The human model is developed to have dimensions obtained from the Korean anthropometric data reported in 1992. Its graphical representation is based on a wire-frame model but, whenever necessary, body segments can be represented by a solid model with hidden line/faces removed and shaded. Workplace models are presented for cabs of the excavator, one of the most popular construction vehicles. A workplace model consists of an operator seat, a steering wheel. two control levers, two pedals, and a control panel. The workplace elements can be modified in their sizes, positions, and orientations by changing the reference point and design parameters. An algorithm for the view test is suggested and loaded to provide a visual evaluaiton of the overall layout of a workplace model.

• 대한조선학회논문집
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• 제32권4호
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• pp.9-18
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• 1995

국내에서 사용되고 있는 CAD/CAM 시스템들은 모두 도입한 제품들로, 그 구조가 폐쇄형으로 되어있기 때문에, 원천기술을 갖고있지 못한 후발 개발자들은 그 내부구조를 파악하기 어렵다. 근래에 정보기술분야에서 개방형 구조를 갖는 시스템들이 등장하여 좋은 기회를 제공하고 있다. 이 글에서는 개방형 구조를 갖는 형상모델러를 개발하기 위하여 그 시스템설계를 수행한 내용을 소개한다. 기존의 유사한 형상모델러들을 조사분석하여, 새로운 시스템이 갖추어야하는 기능들을 파악하였으며, 공학설계의 전 과정을 형상모델러가 유연하게 지원하기 위하여 복합다양체를 지원하는 자료구조를 갖는 것이 필요하다고 판단하였다. 이를 토대로 개방형 구조를 갖는 형상모델러의 골격에 대한 기준모델이 제안되었다. 이러한 기준모델과 자료구조, 그리고 공통의 개발환경은 시스템 개발을 위한 여러 사람의 참여와, 업무분담, 그리고 분담개발된 요소기능들의 통합을 지원하는 유효한 수단이 될 것이다.