• Korean Journal of Optics and Photonics
• /
• v.28 no.6
• /
• pp.295-303
• /
• 2017

In this paper, we have studied a method of forming a line beam using a UV LED. The existing linear-type UV LED curing optical system is composed of several cylindrical lenses, but problems such as optical system alignment, enlargement of the module, efficiency, etc. may arise in the future. As an alternative to these problems, a bar-type TIR lens having a freeform surface only in the y-axis direction is designed, to verify that it shows advantages in maximum illuminance, uniformity of illuminance, and flux efficiency.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.2160-2163
• /
• 2005

Solid freeform fabrication (SFF) technology plays a major role in industry and represents a reasonable percentage of industrial rapid prototyping/tooling/manufacturing (RP/RT/RM) development applications. However, SFF technology still has long way to progress to achieve satisfactory process speed, surface finish and overall quality improvement of its application. Today, three dimensional printing (3DP) technique that is one of SFF technology is receiving many interests, and is applied by various fields. It can fabricate three dimensional objects of solid freeform with high speed and low cost using ink jet printing technology. However, need long curing time after manufacture completion. And it must do post-processing process necessarily to heighten strength of objects because strength of fabricated objects is very weak. Therefore, in this study, we proposed an improved 3DP process that can solve problems of conventional 3DP process. The general 3DP process is method to spout binder simply through printer head on powder, but proposed process is method to cure jetted UV resin by UV lamp after jet UV resin using printhead on powder. The hardening of resin is achieved strongly at early time by UV lamp in proposed method. So, the proposed process can fabricate three dimensional objects with high speed without any post-processing.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.595-598
• /
• 2002

Laser scanners are getting used more and more in reverse engineering and inspection. For CNC-driven laser scanners, it is important to automate the scanning operations to improve the accuracy of capture point data and to reduce scanning time in industry. However, there are few research works on laser scan planning system. In addition, it is difficult to directly analyze multi-patched freeform models. In this paper, we propose an STL (Stereolithography) mesh based laser scan planning system for complex freeform surfaces. The scan planning system consists of three steps and it is assumed that the CAD model of the part exists. Firstly, the surface model is approximated into STL meshes. From the mesh model, normal vector of each node point is estimated. Second, scan directions and regions are determined through the region growing method. Also, scan paths are generated by calculating the minimum-bounding rectangle of points that can be scanned in each scan direction. Finally, the generated scan directions and paths are validated by checking optical constraints and the collision between the laser probe and the part to be scanned.

• Journal of Computational Design and Engineering
• /
• v.1 no.1
• /
• pp.27-36
• /
• 2014

Similar to the essential components of many mechanical systems, the geometrical properties of the teeth of spiral bevel gears greatly influence the kinematic and dynamic behaviors of mechanical systems. Logarithmic spiral bevel gears show a unique advantage in transmission due to their constant spiral angle property. However, a mathematical model suitable for accurate digital modeling, differential geometrical characteristics, and related contact analysis methods for tooth surfaces have not been deeply investigated, since such gears are not convenient in traditional cutting manufacturing in the gear industry. Accurate mathematical modeling of the tooth surface geometry for logarithmic spiral bevel gears is developed in this study, based on the basic gearing kinematics and spherical involute geometry along with the tangent planes geometry; actually, the tooth surface is a parametric surface defined on a parallelogrammic domain. Equivalence proof of the tooth surface geometry is then given in order to greatly simplify the mathematical model. As major factors affecting the lubrication, surface fatigue, contact stress, wear, and manufacturability of gear teeth, the differential geometrical characteristics of the tooth surface are summarized using classical fundamental forms. By using the geometrical properties mentioned, manufacturability (and its limitation in logarithmic spiral bevel gears) is analyzed using precision forging and multiaxis freeform milling, rather than classical cradle-type machine tool based milling or hobbing. Geometry and manufacturability analysis results show that logarithmic spiral gears have many application advantages, but many urgent issues such as contact tooth analysis for precision plastic forming and multiaxis freeform milling also need to be solved in a further study.

• Journal of the Society of Naval Architects of Korea
• /
• v.38 no.2
• /
• pp.53-61
• /
• 2001

A cutting machine for freeform hull surfaces of ship models is developed and a servo system is employed for tool path control. The servo system consists of BLDC(Blushless DC) motor, control driver and host controller. Also PI controller is applied for precision processing. GUI(Graphic User Interface) was realized by visual c++ for the convenience of users. Free form surfaces are formed by the cutting machine developed in the Ocean Engineering Wide Tank of the University of Ulsan.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.142-145
• /
• 2004

More complex geometric shapes, including freeform surfaces, are adopted for the design of products to emphasize styling or aesthetics. Modeling of these products is extremely difficult, and often impossible. Reverse engineering is an emerging technology that can resolve this problem by generating CAD models from the physical mockups or prototype models. The laser scanner if often used to acquire the surface information of the part, but is limited in its measuring direction, which if fixed only along the z-axis. A Designed fixture of new shape to supplement these problems in this paper. The new fixture using several joints and an tooling ball holder is designed considering the convenience of the part set-up and the accuracy of the registration. The location of the tooling balls can be arranged to avoid the occlusion of the part and to minimize the registration error. The new fixture is apply to an object part having freeform surfaces to verify the effectiveness of the proposed design.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1740-1743
• /
• 2002

This paper presents the basic concept of a Solid Freeform Fabrication System using a rapid prototyping procedure. The system can fabricate a ceramic model by laser cutting, accumulating, laminating and sintering of each slice. The system is mainly equipped with a laser apparatus, an x-y table, a material transfer system, and an electric oven. The system could fabricate a small object with smooth surface within comparatively short period of time. The system has also shown its effectiveness in terms of the direct application of the object without the secondary mechanical process. The fabricated sample could directly be applied and used to fairly wide practical areas.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2015.05a
• /
• pp.126-127
• /
• 2015

New technologies using a CNC machine to reduce the production cost of free-form buildings are being developed. To produce free-form members with such technologies, a vast free form building should be first divided into multiple panels that can be produced. Considering the curved surface of free-form buildings, the shape and size of divided freeform panels vary, which will lead to a great deal of errors. Currently, the engineers and designers complete the panelizing work through trials and errors even in large-scale projects, which results in increased construction duration and cost. Thus, it is necessary to develop a freeform panelizing technology to maximize the economic effects of free-form concrete member production technology. The purpose of the study is to analyze influence factors on panelizing of free-form buildings, which is a preceding research for development of a panelizing technology. The influence factors drawn will provide a core basis for development of panelizing technologies for free-form buildings.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.915-918
• /
• 2005

Advances in Information Technology and in Biomedicine have created new uses for CAD technology with many novel and important biomedical applications. Such applications can be found, for example, in the design and modeling of orthopedics, medical implants, and tissue modeling in which CAD can be used to describe the morphology, heterogeneity, and organizational structure of tissue and anatomy. CAD has also played an important role in computer-aided tissue engineering for biomimetic design, analysis, simulation and freeform fabrication of tissue scaffolds and substitutes. And all the applications require precision geometry of the organs or bones of each patient. But the geometry information currently used is polygon model with none solid geometry and is so rough that it cannot be utilized for accurate analysis, simulation and fabrication. Therefore a case study is performed to deduce a transformation method to build free form surface from a rough polygon data or medical images currently used in the application. This paper describes the transformation procedure in detail and the considerations for accurate organ modeling are discussed.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2017.05a
• /
• pp.58-59
• /
• 2017

Through the case study, we surveyed the performance of a CNC-T BAR system on irregular-shaped building construction project. By CNC T-BAR system, we mean a surface curvature control system has been used in aircraft and ship manufacturing by controlling entire surface points on shape. For the past 10 year, the number of irregularly-shaped building design and construction project has been increased, and also the studies on irregular-shaped construction methods have been conducted. However, the previous studies did not review on the performance of the CNC T-BAR system. We collected construction-completed cases in Korea, which applied the CNC T-BAR system, and we studied its performance by comparing with a segment system in terms of construction duration and its quality. The result shows that the CNC T-BAR system can shorten the construction duration comparing with segment-assembly system while maintaining high quality. The CNC T-BAR system is expected to apply on the more number of irregularly-shape building construction project.