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

• 한국CDE학회논문집
• /
• 제10권5호
• /
• pp.328-338
• /
• 2005

CAD systems are routinely used by designers for creating part geometries. Interfaces to CAE/CAM systems are also commonplace enabling the FEA-based design optimization and the rapid fabrication of the designed part. However, conventional CAD systems have thus far focused on objects with homogeneous interior. Two recent advances--use of heterogeneous objects such as Functionally Graded Materials (FGM) in parts and Layered Manufacturing Technology (LMT)--have brought to the forefront the need for CAD systems to support the creation of geometry as well as the graded material inside. We first describe the need and the components of such a CAD system for heterogeneous objects. A prototype CAD system is then described with one specific example (thermal barrier type FGM, pressure vessel) in order to illustrate the use of the implemented CAD system. The implemented system is manually integrated with FEA tools for optimal design. Our ongoing work involves the automation of the integration with FEA tools.

• 한국CDE학회논문집
• /
• 제6권4호
• /
• pp.254-262
• /
• 2001

It is not possible to exchange parametric information of CAD (Computer Aided Design) models based on the current version of STEP (Standard leer the Exchange of Product model data). The design intent can be lost during the STEP transfer of CAD models. The ISO Parametrics Group has proposed the SMCH (Solid Model Construction History) schema in June 2000 that includes structures fur exchange of parametric information. This paper proposes the macro parametric approach that is intended to provide capabilities to transfer parametric information. In this approach, CAD models are exchanged in the form of macro files. The macro file contains user commands which are used in the modeling phase. To exchange CAD models using the macro parametric approach, modeling commands of commercial CAD systems are analyzed. Those commands are classified by the grouping method suggested by Bill Anderson. As a neutral file format, a standard modeling commands set has been defined. Mapping relations between the standard modeling commands set and the native modeling commands set of commercial CAD systems are defined.

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

• 한국의류학회지
• /
• 제19권2호
• /
• pp.242-263
• /
• 1995

The study was to find out the current situation of supply and demand of apparel CAD systems in Korea. Also it was hoped to gather any valuable information about the current usage of apparel CAD systems for the development of the enhanced apparel CAD system. Three interviews were carried out for the study. The first interview with the importing agents was to find out the apparel CAD system's supplying situation. The second interview with the users of apparel CAD system was about the usage of the systems and related informations. The last interview was about the pattern making facilities, which was pointed out by the users to be the most inconvenient part of apparel CAD systems. The results of the survey were: 1. The supply and demand of apparel CAD systems is increasing. 2. The education, training, maintenance of the system should be improved by the supplier. 3. Apparel CAD systems are used for various production systems in the apparel industry. 4. 100% of the systems are utilized for pattern input and 89% of the systems are utilized for marker making. Only 15% of the systems are utilized in pattern making process, which 80% of the users realize to be computerized. 5. The most serious barrier to the better usage of the system is the communication with the system in foreign language. This barrier could be lifted when Korean apparel CAD system is developed.

• 대한인간공학회:학술대회논문집
• /
• 대한인간공학회 1993년도 추계학술대회논문집
• /
• pp.165-188
• /
• 1993

The study was to find out the current situation of supply and demand of apparel CAD systems in Korea. Also it was hoped to gather any valuable information about the curent usage of appared CAD systems for the development of the enhanced apparel CAD system. Three interviews were carried out for the study. The first interview with the importing agents was to find out the apparel CAD system's supplying situation. The second interview with the users of apparel CAD system was about the usage of the systems and related informations. The last interview was about the pattern making facilities, which was pointed out by the users to be the most inconvenient prat of apparel CAD systems. The results of the survey were:- 1. The supplu and demand of apparel CAD systems is increasing. 2. The education, training, maintenance of the system should be improved by the supplier. 3. Apparel CAD systems are used for various production systems in the apparel industry. 4. 100% of the systems are utilized for pattern input and 89% of the systems are utilized for marker making. Only 15% of the systems are utilized in pattern making process, which 80% of the users realize to be computerized. 5. The most serious barrier to the better usage of the system is the communication with the system in foreign language. This barrier could be lifted when Korean apparel CAD system is developed.

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

• 한국건설관리학회:학술대회논문집
• /
• 한국건설관리학회 2008년도 정기학술발표대회 논문집
• /
• pp.291-296
• /
• 2008

지난 20년간 3D/4D CAD에 관한 연구는 시설물 생애주기의 설계, 시공단계를 중심으로 활발히 진행되어 왔지만 시설물 생애주기 전반에 걸쳐서 3D/4D CAD의 유용성에 관한 연구는 아직까지 미흡한 실정이다. 본 연구에서는 설계, 시공단계에 국한하지 않고 시설물 생애주기 동안의 3D/4D CAD 사용에 따른 유용성을 도출하기 위하여 현재 상용화된 소프트웨어를 사용하여 3D/4D CAD 모델을 생성하였다. 생성된 모델과 기존의 시설물 생애주기 관리 방법을 기반으로 전문가와 포커스 그룹 인터뷰를 실시하여 그 결과를 바탕으로 155명의 시설물 생애주기 관련 업무 수행자들의 설문조사를 통해 3D/4D CAD를 통한 시설물 생애주기 관리 유용성을 도출하였다.

• 한국건설관리학회:학술대회논문집
• /
• 한국건설관리학회 2006년도 정기학술발표대회 논문집
• /
• pp.154-160
• /
• 2006

건설산업분야에 CAD시스템이 도입된 이래 CAD로 작성된 도면으로부터의 물량산출에 관한 연구가 지난 20여 년간 많은 관심 속에 국내외 적으로 지속되어 왔으나, 성과는 그다지 만족스럽지 못하였다. 특히 3D CAD 시스템을 활용한 설계 및 물량산출은 제조업에서는 괄목할 만한 성과를 거두고 있음에도 불구하고 건설 산업에서는 3D CAD 시스템에 의한 물량산출시스템의 개발 및 운영에 많은 어려움이 있다. 3D CAD 시스템에서는 3D 라이브러리(3D Object)의 구축 및 활용이 매우 중요하며 건설 산업의 특성상 설계과정에서 발생하는 신규 부재(3D object)에 대한 신속한 지원이 없이는 설계 및 물량산출에 3D CAD 시스템의 활용에 많은 어려움이 있다. 또한 3D CAD 모델로 부터의 물량산출을 지원하는 시스템은 개념설계(schematic design)단계에서도 개략견적이 가능하여야 하며, 상세설계(detailed design) 단계 및 시공도면작성(construction design)단계에 이르는 각 단계마다 물량산출 및 비용 산출이 가능하여야 한다. 다음으로는 설계과정 및 의사결정단계를 거치면서 계속 진화하는 설계변경(revision)에 따라 유연하게 물량 및 비용 산출이 가능하여야 한다. 본 연구에서는 3D 모델을 기반으로 한 상용화된 5D(3D+cost+schedule) CAD 시스템인 컨스트럭터(Constructor)의 기본개념을 살펴보고 특히 레서피(Recipe)기반의 물량산출 모듈에 대한 설명 및 시범 프로젝트 적용결과에 대해 검토하고 앞으로의 기대효과 및 건설 산업에서의 3D CAD 기반 응용시스템 연구 방향에 대해 살펴보고자 한다.

• 건축사
• /
• 6호통권219호
• /
• pp.74-83
• /
• 1987

CAD시스템을 도입하여 활용하고 있는 필자의 경험을 토대로 하여 현재 CAD시스템의 도입을 검토하고 있거나 혹은 관심을 가지고 있는 설계사무실의 입장에 서서 결코 만만치 않은 가격의 CAD시스템을 어떻게 이해하고 활용할 것인가 하는 것을 중점적으로 고찰하였다. 지면사정상 깊이있는 이론적 설명은 배제하고 사무실에서 부딪히는 현실적인 문제를 위주로 기술하였으므로 경영하자 CAD책임자에게 특히 도움이 될 수 있었으면 한다.