• 정보처리학회논문지A
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• 제13A권1호
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• pp.27-34
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• 2006

디자인 워킹 그룹에서 설계자가 CAD 툴을 사용하기 위해서는 현재 속한 그룹에서 사용 할 수 있는 CAD 틀 및 라이센스의 종류, 개수 및 설정 방법을 알아야 하고, 이 정보는 해당 그룹에 속한 관리자를 통해 얻는다. 기존의 CAD 툴/라이센스 공유 방법은 설계자가 CAD 툴 및 라이센스에 대한 정보를 획득하는 과정이 관리자와의 수작업을 통한 통신으로 이루어 졌으며, 해당 정보를 획득한 후에는 설계자가 직접 환경 설정을 해야 한다. 이와 같은 환경에서는 새로운 설계자가 특정 그룹에 들어왔을 때, 정보를 얻기 위한 통신과 설정 과정으로 인해 불필요한 설계시간을 소모하게 되어 결국 생산성 및 CAD 툴의 이용률을 저하시킨다. 또한, 관리자의 입장에서도 모든 설계자들에게 CAD 툴 및 라이센스에 대한 정보를 제공하기 위해서는 많은 시간 및 노력비용을 소모하게 된다. 본 논문에서는 디렉토리 서비스에 기반하여 특정 디자인 워킹 그룹에서 CAD 툴 및 라이센스를 자동화된 방법으로 공유하기 위한 방식을 제안한다. 본 논문에서 제안한 방법은 사용자와 관리자 사이의 통신부분을 자동화하여, 관련 정보 공유를 위해 소비되던 불필요한 시간을 최소화시킨다. 또한, 디렉토리 서비스를 이용하여 설계자와 관리자 사이의 CAD 툴 및 라이센스 정보에 대한 일관성을 항상 자동으로 유지함으로써, 설계자와 관리자 사이의 반복된 CAD 툴 및 라이센스 설정에 대한 정보 교환 작업을 제거하여 공유의 효율성을 높이고, 프락시를 사용하여 수동으로 진행되던 설계자의 환경 설정 과정을 자동화한다. 또한, 실행 가능한 프락시를 이용하여 씬 클라이언트 CAD 어플리케이션을 제공한다. 제안된 방법은 Sun Microsystems의 Jini 기술을 이용하여 구현한다. 본 논문에서 제안한 CAD 툴 및 라이센스 공유 시스템은 결과적으로 설계자와 관리자의 불필요한 설계 시간과 노력비용을 감소시키고, CAD 툴의 이용률을 향상시킬 수 있을 것이라고 사료된다.

• 대한산업공학회지
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• 제18권2호
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• pp.11-22
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• 1992

Up to now, most researches on production automation have concentrated on local automation, e. g. CAD, CAM, robotics, etc. However, to achieve total automation it is required to link each local modules such as CAD, CAM into a unified and integrated system. One such missing link is between CAD and computer vision system. This thesis is an attempt to link the gap between CAD and computer vision system. In this paper, we propose algorithms that carry out edge detection, thinning and pruning from the image data of manufactured parts, which are obtained from video camera and then transmitted to computer. We also propose a feature extraction and surface determination algorithm which extract informations from the image data. The informations are compatible to IGES CAD data. In addition, we suggest a methodology to reduce search efforts for CAD data bases. The methodology is based on graph submatching algorithm in GEFG(Generalized Edge Face Graph) representation for each part.

• 대한기계학회논문집A
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• 제31권6호
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• pp.635-643
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• 2007

As many engineers and technicians are involved in the design process of large scale and/or complex products, there are a lot of miss matches and interferences due to designers' faults and several kinds of CAD systems. Recently, CAD systems are applied to verify and check the assembly process. Digital Mock-Up(DMU) system, a tool to build a virtual mock-up in the design stage, has been used to prevent the interferences and miss matches during precision design processes. Using the virtual assembly tool, engineers are able to design precision and interference free parts without physical mock-ups. Instead of a single CAD source, several CAD systems are used to design a complex product. Several organizations are involved in the distributed design environment for heterogeneous multi-CAD assembly. XML and the lightweight CAD file are proposed for the multi-CAD assembly. XML data contains hierarchy of the heterogenenous multi-CAD assembly. STEP PDM schema and STEP ISO 10303-28 formations are applied to construct the XML data. The lightweight CAD file produced from various CAD files through ACIS kernel and InterOp not only contains mesn, B-Rep and topological data, but also is used to visualize CAD data and to verify dimensions. Developed system is executed on the desktop computers. It does not require commercial CAD systems to visualize 3D assembly data. Real-time interference and fitness checks, dimensional verification, and design and assembly verification are performed on the developed system. Assembly of heterogeneous models for a car is conducted to verify the effectiveness of the developed DMU system on the Internet.

• 디자인학연구
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• 제17권1호
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• pp.241-252
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• 2004

CAD는 이미 디자인 분야에서도 중요하게 사용되는 도구로 동시 공학적 프로세스 상에서 전통적인 디자인 방법은 점점 사라져 가고 있다. 하지만, 리버스 엔지니어링(Reverse Engineering) 방식의 CAD 도구는 디자이너들의 작업을 위해 사용하는 도구로는 아직 많은 문제점들을 가지고 있다. 특히 디자인 프로세스 초기 단계의 직관적인 작업의 특성으로 인해 디자이너들이 기존의 CAD 도구들을 이 단계에서 적용하기는 거의 불가능하다. 최근 이러한 정성적인 문제들에 대해 구체적으로 접근하려는 연구들이 소프트웨어 뿐 아니라 하드웨어적 측면에서도 이루어지고 있다. 이 글에서는 디자인 프로세스 상에서 사용되는 기존의 3D CAD 도구의 문제점들과 최근 연구되고 있는 새로운 인터페이스 접근 방법들에 대해 알아보았다. 또한 디자이너들을 위한 CAD 개발을 위한 가이드라인을 제시하고 이를 통해 유비쿼터스 컴퓨팅 환경에서 효율적으로 사용할 수 있는 디자인 도구를 개발하기 위한 방안을 제시하였다.

• International Journal of CAD/CAM
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• 제9권1호
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• pp.17-24
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• 2010

For several years, researchers have focused on improving the integration of the CAD, CAM and Analysis through a better communication between the various analysis tools. This tendency to integrate the CAD/Analysis and automation of the corresponding processes requires data sharing between the various tasks using an integrated product model. We are interested in this research orientation to CAD/CAM/Analysis integration by rebuilding the CAD model (BREP), starting from the Analysis results (deformed mesh). Because this problem is complex, it requires to be split into several complementary parts. This paper presents an original interoperability process between the CAD and CAE. This approach is based on a new technique of rebuilding the CAD surface model (Nurbs, Bezier, etc.) starting from triangulation (meshed surface) as a main step of the BREP solid model. In our work, the advantages of this approach are identified using a centrifugal pump example.

• International Journal of CAD/CAM
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• 제2권1호
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• pp.13-21
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• 2002

It is not possible to exchange parametric information of CAD models based on the current version of STEP. The design intent can be lost during the STEP transfer of CAD models. The Parametrics Group of ISO/TC184/SC4 has proposed the SMCH schema, which includes constructs for exchange of parametric information. This paper proposes a macro-parametric approach that is intended to provide capabilities to transfer parametric information including design intents. In this approach, CAD models are exchanged in the form of macro files. The macro file contains the history of user commands, which are used in the modeling phase. To exchange CAD models using the macro-parametric approach, the modeling commands of several commercial CAD systems are analyzed. Those commands are classified and a set of standard modeling commands has been defined. Mapping relations between the standard modeling commands and the native modeling commands of commercial CAD systems are defined. The scope of the current version is limited to parts modeling, not assemblies.

• 한국CDE학회논문집
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• 제11권6호
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• pp.447-454
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• 2006

Although there are many needs to use 3D models in MEMS field, it is not easy to generate 3D models based on MEMS CAD. This is because MEMS CAD is based on 2D and their popular format-GDSII file format- has its own limits and problems. The differences between GDSII file format and 3D CAD system, such as (1) superposed modeling, (2) duplicated entity, (3) restricted of entity type, give rise to several problems in data exchange. These limits and problems in GDSII file format have prevented 3D CAD system from generating 3D models from the MEMS CAD. To remove these limits and solve problems, it is important to extract the silhouette of data in the MEMS CAD. The proposed method has two main processes to extract silhouette; one is to extract the pseudo-silhouette from the original 2D MEMS data and the other is to remove useless objects to complete the silhouette. The paper reports on the experience gained in data exchange between 2D MEMS data and 3D models by the proposed method and a case study is presented, which employs the proposed method using MEMS CAD IntelliMask and Solidworks.

• International Journal of CAD/CAM
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• 제7권1호
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• pp.1-10
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• 2007

The compression of CAD models is a key technology for realizing Internet-based collaborative product development because big model sizes often prohibit us to achieve a rapid product information transmission. Although there exist some algorithms for compressing discrete CAD models, original precise CAD models are focused on in this paper. Here, the characteristics of hierarchical structures in CAD models and the distribution of their redundant data are exploited for developing a novel data encoding method. In the method, different encoding rules are applied to different types of data. Geometric data is a major concern for reducing model sizes. For geometric data, the control points of B-spline curves and surfaces are compressed with the second-order predictions in a local coordinate system. Based on analysis to the distortion induced by quantization, an efficient method for computation of the distortion is provided. The results indicate that the data size of CAD models can be decreased efficiently after compressed with the proposed method.

• 대한조선학회논문집
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• 제43권3호
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• pp.362-374
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• 2006

Currently, all design information of a hull structure is being first defined on 2D drawings not 3D CAD model at the initial ship design stage and then transferred to following design stages through the 2D drawings. This is caused by the past design practice, limitation on time, and lack of hull structural CAD systems supporting the initial design stage. As a result, the following design tasks such as the process planning and scheduling are being manually performed using the 2D drawings. For solving this problem, a data structure supporting the initial design stage is proposed and a prototype system is developed based on the data structure. The applicability of the system is demonstrated by applying it to various examples. The results show that the system can be effectively used for generating the 3D CAD model of the hull structure at the initial design stage.

• 대한치과교정학회지
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• 제49권6호
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• pp.404-412
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• 2019

Objective: To assess shear bond strength and failure mode (Adhesive Remnant Index, ARI) of orthodontic brackets bonded to polymethylmethacrylate (PMMA) blocks for computer-aided design/manufacture (CAD/CAM) fabrication of temporary restorations, following substrate chemical or mechanical treatment. Methods: Two types of PMMA blocks were tested: $CAD-Temp^{(R)}$ (VITA) and $Telio^{(R)}$ CAD (Ivoclar-Vivadent). The substrate was roughened with 320-grit sandpaper, simulating a fine-grit diamond bur. Two universal adhesives, Scotchbond Universal Adhesive (SU) and Assure Plus (AP), and a conventional adhesive, Transbond XT Primer (XTP; control), were used in combination with Transbond XT Paste to bond the brackets. Six experimental groups were formed: (1) $CAD-Temp^{(R)}/SU$; (2) $CAD-Temp^{(R)}/AP$; (3) $CAD-Temp^{(R)}/XTP$; (4) $Telio^{(R)}$ CAD/SU; (5) $Telio^{(R)}$ CAD/AP; (6) $Telio^{(R)}$ CAD/XTP. Shear bond strength and ARI were assessed. On 1 extra block for each PMMA-based material surfaces were roughened with 180-grit sandpaper, simulating a normal/medium-grit ($100{\mu}m$) diamond bur, and brackets were bonded. Shear bond strengths and ARI scores were compared with those of groups 3, 6. Results: On $CAD-Temp^{(R)}$ significantly higher bracket bond strengths than on $Telio^{(R)}$ CAD were recorded. With XTP significantly lower levels of adhesion were reached than using SU or AP. Roughening with a coarser bur resulted in a significant increase in adhesion. Conclusions: Bracket bonding to CAD/CAM PMMA can be promoted by grinding the substrate with a normal/medium-grit bur or by coating the intact surface with universal adhesives. With appropriate pretreatments, bracket adhesion to CAD/CAM PMMA temporary restorations can be enhanced to clinically satisfactory levels.