• Journal of Computational Design and Engineering
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• v.1 no.2
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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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• v.7 no.1
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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.

• Journal of Korea Multimedia Society
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• v.3 no.1
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• pp.63-76
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• 2000

Most work done in CSCW (Computer Supported Collaborative Work) system has been targeted toward supporting the exchange of documents or messages among group members, and yet support for cognitive aspects such as group organization, division and merge of work, and work flow control. The objective of the study is to provide CSCW environment for the engineering design process such as CAD (Computer Aided Design) and CASE (Computer Aided Software Engineering). The proposed DCWA (Distributed Collaborative Writing Aid) system suggests a mechanism that unifies the group organization, work division, and work flow control in the CAO, CASE, and software simulation tool. In particular, CAD relates the group and work partition by providing expressing the relation of drawing object (e.g., binding, attachment, and proportional scaling) which is owned by different members of group, and CASE combining with the simulation tool supports the flexibility of the work flow control. Simulating the prototype before manu-facturing a product can reduce time and cost in development.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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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.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.4
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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.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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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.

• Korean Journal of Computational Design and Engineering
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• v.13 no.4
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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 Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.912-920
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• 2002

As computer systems and communication technologies develop rapidly, CSCW(Computer Supported Collaborative Work) system appears nowadays, through which it is available to work on virtual space without any restriction of time and place. Most of CWCS systems depend on a special network and groupware. The systems of graphics and CAD are not so many because they are specified by hardware and application software. We propose a Web-based collaborative CAD system which is independent from any platforms, and develop a 3D solid modeler in the system. This system can be worked in the environment of Client/Server architecture. Clients connect to the design server through Java applet on WWW. The server is implemented by Java application.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.5
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• pp.747-754
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• 2002

We propose a Web-based collaborative CAD system which is independent from any platforms, and develop a 3D solid modeler in the system. We developed a new prototype of 3D solid modeler based on the web using Java 3D API, which could be executed without any 3D graphics software and worked collaboratively interacting with each user. The modeler can create primitive objects and get various 3D objects by using loader. The interactive control is available to manipulate-objects such as picking, translating, rotating, zooming. Users connect to this solid modeler and they can create 3D objects and modify them as they want. When this solid modeler is imported to collaborative design system, it will be proved its real worth in today's CAD system. Moreover, if we improve this solid modeler adding to the 3D graphic features such as rendering and animation, it will be able to support more detail design and effect view.

• Proceedings of the Korea Society of Design Studies Conference
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• 2005.10a
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• pp.182-183
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• 2005