• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.103-115
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• 2014

The engineering design process is a creative process, and the designers must repeatedly apply Undo/Redo operations to modify CAD models to explore new solutions. Undo/Redo has become one of most important functions in interactive graphics and CAD systems. Undo/Redo in a collaborative CAD system is also very helpful for collaborative awareness among a group of cooperative designers to eliminate misunderstanding and to recover from design error. However, Undo/Redo in a collaborative CAD system is much more complicated. This is because a single erroneous operation is propagated to other remote sites, and operations are interleaved at different sites. This paper presents a multi-user selective Undo/Redo approach in full distributed collaborative CAD systems. We use site ID and State Vectors to locate the Undo/Redo target at each site. By analyzing the composition of the complex CAD model, a tree-like structure called Feature Combination Hierarchy is presented to describe the decomposition of a CAD model. Based on this structure, the dependency relationship among features is clarified. B-Rep re-evaluation is simplified with the assistance of the Feature Combination Hierarchy. It can be proven that the proposed Undo/Redo approach satisfies the intention preservation and consistency maintenance correctness criteria for collaborative systems.

• 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.

• 한국멀티미디어학회논문지
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• 제3권1호
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• pp.63-76
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• 2000

기존의 CSCW (Computer Supported Collaborative Work) 시스템은 단순히 문서나 메시지를 구성하고 전달하는 기능만을 지원할 뿐 협동 작업자들간의 조직구성, 업무분할 및 통합, 작업흐름 제어와 같은 인지학적 기능등은 효과적으로 반영하지 못하고 있다. 본 연구는 협동작업환경에서의 CAD(Computer Aided Design)/CASE(Computer Aided Software Engineering)와 같은 공학 디자인 프로세스를 인지학적으로 지원하기 위한 CSCW 시스템을 개발하는 데 그 목적이 있다. 제안된 DCWA (Distributed Collaborative Writing Aid) 시스템은 CAD/CASE 및 시뮬레이션 기능을 하나의 시스템으로 통합함으로써 조직구성, 업무분할, 작업흐름제어가 이들 기능에 통일적으로 적용될 수 잇도록 하였다. 특히 CAD 도구에서는 다중 사용자들 소유의 그림객체 간의 바인딩, 어태치먼트, 스케일링 기능들은 제공하여 결합 형태 및 정도를 나타내는 관계성 표현이 가능하도록 함으로써 업무분할 및 병합이 CAD 도구에서도 명확히 드러나도록 하였고, CASE 도구에서는 소프트웨어 시뮬레이션 기능과 연계하여 작업흐름 제어가 용이하도록 하였다. 이는 또한 제품을 생산하기 전에 미리 모형을 시뮬레이션 해봄으로써 제품 개발의 시간과 비용을 단축할 수 있는 효과를 가져다 준다.

• 한국정보통신학회:학술대회논문집
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• 한국해양정보통신학회 2000년도 추계종합학술대회
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• pp.364-367
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• 2000

As computer system and information/communication technology develop rapidly, nowadays CSCW(Computer Supported Collaborative Work) system appears, through which it is available to work on virtual space without any restriction of time and place. Most of Un systems depend on a special network and groupware. The systems of graphics and CAD are not so many because they are characterized by Hardware and application software. In this paper, we propose a web-based collaborative CAD system which can be jointly worked on Internet WWW being independent from any platforms. It can generate and handle objects easily using lava 3D, and it can transmit, print, and store them. The interactive work for designing objects can be also carried out through dialling with each other. This system is executed in the environment of Client/server. Clients connect to the server through lava applet on WWW. The server is implemented by lava application, and it consists of three components : connection manager which controls the contact to users, work manager which keeps viewing in concurrency and provides virtual work space sharing with others, and solid modeler which generates 3D object.

• 산업경영시스템학회지
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• 제32권4호
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• pp.169-177
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• 2009

Concurrent Engineering (CE) has presented new possibilities for successful product development by incorporating various product life-cycle functions from the earlier stage of design. In the product design, geometric representation is vital not only in its traditional role as a means of communicating design information but also in its role as a means of externalizing designer's thought process by visualizing the design product. During the last dozens of years, there has been extraordinary development of computer-aided tools intended to generate, present or communicate 3D models. However, there has not been comparable progress in the development of 3D-CAD systems intended to represent and manipulate a variety of product life-cycle information in a consistent manner. In the previous research, the authors proposed a novel concept called Minus Volume (MV) to incorporate various design information relevant to product life-cycle functions. This paper proposes the use of the MV concept for the collaborative design environment, where many team members are geographically distributed over the networked environment, including Internet, Intranet, WWW, etc. A prototype 3D-CAD system is implemented based on the MV concept and illustrated with the successful implementation of collaborative design example.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.509-513
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• 1996

The information technology of computers and computer tools have become so powerful that virtual enterprises are not just concepts any longer The virtual enterprises comprise distributed facilities and it is necessary to have a collaborative system among them. This paper proposes the modeling process of web-based collaborative system in the distributed manufacturing environment. It also presents the information infrastructure in order to communicate and to share the information more efficiently among the collaboration subsystem. The web-based collaborative system consists of four processes: 1) product design, 2) procurement of DB information, 3) query process, and 4) negotiation. The proposed web-based collaborative system will be implemented with network technologies.

• 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.

• 한국통신학회논문지
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• 제27권10C호
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• pp.912-920
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• 2002

오늘날 컴퓨터와 통신 기술의 발달로 시간과 공간의 제약 없이 공유된 가상 공간에서 작업을 하는 컴퓨터 지원 협동 시스템(CSCW)이 등장하고 있다. 그러나 대부분의 시스템은 그룹웨어를 사용하고, 공유객체는 윈도우 탐색기 형태를 지니고 있고, CAD를 비롯하여 그래픽 분야의 시스템은 하드웨어와 응용 소프트웨어에 크게 의존하기 때문에 협동시스템이 많지 않다. 본 논문은 인터넷 웹 상에서 협동작업으로 이루어지는 CAD시스템의 3차원 솔리드 모델러를 제안한다. 이 시스템은 Java와 Java 3D API를 이용하여 개발함으로 플랫폼에 구애받지 않고, 특정한 3차원 그래픽스 소프트웨어 없이 인터넷망과 웹브라우저를 이용하여 공유된 가상 공간에서 협동작업이 이루어지도록 한다. 협동설계 참여자들은 인터넷을 통해 솔리드 모델러 서버에 접근하여 원하는 3D 도형을 생성하고 조작한다.

• 한국정보통신학회논문지
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• 제6권5호
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• pp.747-754
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• 2002

본 논문은 인터넷 웹 상에서 협동작업으로 이루어지는 CAD시스템의 3차원 솔리드 모델러를 보여준다. 협동CAD시스템의 클라이언트는 자바 애플릿을 통해 웹 상에서 접근하고 솔리드 모델러 서버는 접속을 통제하는 접속관리자, 작업 그룹의 동기화를 유지하며 공유작업공간을 확보하는 작업관리자, 그리고 3차원 도형 객체를 생성하고 변형시키는 솔리드 모델러로 이루어져 있다. 솔리드 모델러의 시스템 라이브러리는 워크스페이스 클래스, 뷰 클래스, 평행투영 뷰 클래스, 원근투영 뷰 클래스, 솔리드 클래스 등으로 되어 있다. 기본도형을 생성하여 이동, 회전, 확대·축소하고, 다른 툴을 이용하여 제작한 오브젝트를 불러올 수 있다. 트리 형태의 장면그래프를 사용하므로 전체 구조를 쉽게 알 수 있고, 부분적 결합이 가능하며 오브젝트의 선택이나 조작에 있어서 하위계층을 쉽게 제어할 수 있다. Java 3D를 이용하여 개발함으로 써 많은 그래픽 라이브러리들의 특징을 편리하게 이용할 수 있으며, 다른 라이브러리에서 사용하지 않는 뷰, 렌더렁, 애니메이션 등과 같은 새로운 기술들을 포함시킬 수 있다.

• 한국디자인학회:학술대회논문집
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• 한국디자인학회 2005년도 추계 학술발표대회 논문집
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• pp.182-183
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• 2005