• Proceedings of the Korean Institute Of Construction Engineering and Management
• /
• autumn
• /
• pp.504-508
• /
• 2003

Cost and schedule are the major concerns for the successful construction project management. The four dimensional CAD (4D CAD) integrating graphical data and scheduling data has also been an area of research interests for improving construction controls. In order to achieve the benefits from these areas in an integrated way, this study proposes a 4D-EVMS system for the owners. Managerial requirements for cost and schedule control for the owners are identified first. A 4D-EVMS model is then proposed which provides functional flexibility in order to enhance the efficiency of the system. Lessons learned and practical implications are briefly summarize.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.11
• /
• pp.21-31
• /
• 1998

This study described computer aided die design system for cold forging of non-axisymmetric parts. To design the die of cold forging. an integrated approach based on a rule-base system and commercial F. E. code were adopted. This system is implemented on the personal computer and its environment is a commercial CAD package named as AutoCAD. The system includes four modules. In the initial data input module, the variables which are necessary to design of die are inputted by user and die material are selected from the database. In the analysis and redesign module, stress distrubution action on the designed die is analyzed by commercial FEM code NISA II. The designed die is modified to prevent failure in both states of stress free and pressurizing. The developed system provides powerful capabilities for die design of non-axisymmetric parts.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.10
• /
• pp.46-55
• /
• 1996

As industrial standard data, the STL format which approximates three dimensional CAD model to triangular facets, is used for RP(Rapid Prototyping) system in recent days. Because most RP system take the only form of two dimensional line segments as an input stream inspite of its imperfectness while converting into STL format, a CAD model is converted into a standard industrial format which is composed of many triangular facets. The error verifying process is composed of four main steps, and these are 1) Remove facets with two or more vertices equal to each other. 2) Fix overlapping error such as more than three facets adjacent to anedge. 3) Fill holes in the mesh by using Delaunay triangulation method. 4) Correct the wrong direction and normal vectors. This paper is concerned with serching the mentioned errors in advance and modifying them.

• Korean Journal of Construction Engineering and Management
• /
• v.16 no.4
• /
• pp.30-40
• /
• 2015

Two-dimensional drawings are widely used as a communication tool in the construction industry, but they are still hard to be understood by engineers with less experience. A four dimensional CAD drawing is presented based on marker-based augmented reality, for visual assistance, detailed information, and prevention of misunderstanding among users. The developed drawing enables the users to easily understand its contents through the functions augmenting components, providing detailed construction information, and simulating construction process, using the marker in a 2D drawing. A questionnaire-based survey validates the capability of the developed drawing that it improves inexperienced engineers' understanding of the drawings.

• IE interfaces
• /
• v.11 no.2
• /
• pp.65-78
• /
• 1998

The letters of the automobile tire are usually engraved on the side-wall. The shape of the side-wall is a sculptured surface generated by the rotational sweeping of a profile curve. The letters laid on the side-wall are usually designed by a 2-dimensional CAD. It is impossible to machine the letters on the surface accurately by 3-axis NC machining, because the axis of cutter should be tilted to align with the normal vector of the surface. In this case. the degree of freedom for the machine is at least four. This paper describes an idea for tool path generation of a 4-axis machine by using the 2-dimensional CAD data of the letters and the surface of the side-wall. This study includes the following procedures; (1) measuring the profile of the side-wall surface and curve-fitting of the measured points. (2) the 'non-parallel projection' of the letters on the side-wall, and (3) an inverse kinematics of the 4-axis lettering machine. Procedures in this paper are programmed in C-language on Windows95 environment. With a PC based CNC controller and a 4-axis lettering machine. these are tested sucessfully for the practical use.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.1024-1030
• /
• 1993

In manufacturing press die with free surface, grinding operation is an important post process for surface finish and dimensional accuracy. With the advancement of NC technology. surface grinding operation is increasingly replaced by the gantry type manipulator. As the mechanics for grinding operation is different from machining operation, conventional CAM system for machining operation is hard to apply. In this. paper, we develop a five-axis CAM system by which an efficient gantry trajectory can be planned and verified. The developed system consists of four conceptual modules; namely CAD, PROCESS. CAM, and ANALYSIS. In the CAD module, the machined surface is represented by CL-data or surface modeler, and process parameters are specified by the PROCESS module. Then, the CAM module generates a series of grinding paths based on the grinding mechanics together with process databases for tool spaces and grinding conditions. The generated paths are verified via ANALYSIS module. Validation via real experiments is left for further study.

• Journal of the Ergonomics Society of Korea
• /
• v.21 no.1
• /
• pp.15-26
• /
• 2002

The anthropometric characteristics of the intended user population are most important parameters in the equipment and workplace layout design, particularly in the airplane cockpit design. Because human body is composed of multi-dimensional body segments, single 'average' or 'extreme' manikin is not sufficient in computer-aided design(CAD) environments. To overcome this limitation, we constructed a manikin group representing Korean Male pilot population. First, we identified 16 anthropometric variables which are important parameters in the evaluation of reach, visibility, and clearance. And we found their correlations and conducted a factor analysis. Four common factors were extracted in the factor analysis. The first one was related with length dimensions, the second was with the arm reach, the third was with the sitting height, and the last was with breadth-depth dimensions. Finally, 17 manikins were constructed and presented in the CAD prototype.

• Journal of the Korean Society of Industry Convergence
• /
• v.5 no.1
• /
• pp.11-19
• /
• 2002

This study described computer aided die design system for cold forging of non-axisymmetric parts such as gears and splines. To design the cold forging die, an integrated approach based on a rule-base system and commercial F. E. code were adopted. This system is implemented on the personal computer and its environment is a commercial CAD package named as Auto CAD. The system includes four modules. In the initial data input module, variables which are necessary to design of die are inputted by user and die material are selected from the database according to the variables. In the analysis and redesign module, stress distribution acting on the designed die is analyzed by commercial FEM code NISA II with elastic mode. If die failure predicted, the designed die would modified in four ways to prevent die failure in both states of stress free and pressurizing. The developed system provides useful date and powerful capabilities for die design of non-axisymmetric parts.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.30 no.9_10 s.157
• /
• pp.1485-1493
• /
• 2006

This study was to investigate the effect of different scouring methods on mechanical properties and appearance of lyocell. Two different scouring methods were adopted for the study; one was the traditional scouring with alkali and the other was enzymatic scouring. Enzymatic scouring was carried with four different enzymes; C1 : Cellusoft L, C2 : Cellusoft UL, D1 : Denimax 992L, D2 : Denimax Acid XCL. The mechanical properties of scoured lyocell were measured using KES-FB. The appearance of scoured samples was analyzed by 3D CAD SYSTEM of i-Designer. While the untreated fabric showed the best linearity because it is stiff, alkali treated samples showed the worst dimensional stability and distorted easily. Enzyme treated samples, especially C1 treated samples showed the best dimensional stability. In addition, enzyme treated samples showed low bending rigidity compared to the alkali treated samples. It means that the enzyme treated samples are more flexible than alkali treated samples. However, the smoothness of the sample's surface treated by either of methods did not show much difference. From the study, it was suggested that the enzymatic scouring for lyocell could help to gain natural silhouette.

• Journal of Korean Institute of Industrial Engineers
• /
• v.17 no.1
• /
• pp.37-49
• /
• 1991

This report describes an integrated approach to sculptured surface design and manufacture, and a software package for it on a multi-axis NC milling machine. The integrated software consists of four parts : (1) surface fitting procedure for generating the characteristic polyhedron from 3 dimensional CMM data, (2) surface description for generating the mathematical representation of sculptured surfaces. (3) tool path generation for approximating the surface representation into a sequence of linear cutter paths, and (4) tool control for generating the corresponding joint variable values. This integrated approach is generally applicable to sculptured surface manufacturing where multi-axis milling machines are necessary to produce smooth three-dimensional surfaces.