• Transactions of Materials Processing
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• v.11 no.4
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• pp.323-331
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• 2002

The combination of rapid prototyping(RP) and rapid tooling(RT) has a potential for rapid manufacturing of three-dimensional parts. In the present study, a new RP system transfer type Variable Lamination Manufacturing using Expandable Polystyrene Foam (VLM-ST), is proposed to fabricate net shapes of three-dimensional prototypes. Various three-dimensional parts, such as a knob shape and a human head shape, are manufactured by the VLM-ST apparatus. In addition, a new rapid tooling technology, which utilizes a room temperature vulcanizing (RTV) molding technique and a triple reverse process technique, is proposed to manufacture net shapes of three-dimensional plastic parts using the prototypes of VLM-ST. A plastic part of the knob shape is produced by the proposed RT technology. The combination of the proposed RP and RT enables the manufacture of a plastic knob within two days.

• Transactions of Materials Processing
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• v.10 no.6
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• pp.500-508
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• 2001

The integration of Rapid prototyping (RP) and Rapid Tooling (RT) has the potential for rapid net shaping of thee-dimensional parts, which have a geometrical complexity. In this study, a new R)P process, (VLM-SP), was proposed to manufacture net shapes of three-dimensional prototypes and it was shown that VLM-SP is an effective and economic process through the comparison of building time, building cost and dimensional accuracy for the test parts with the commercial RP processes ; LOM and FDM. In addition, the metal parts, which are a spanner shape and a clover punch, were produced by the plaster casting as one of RT using the prototypes of VLM-SP.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2003.04a
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• pp.428-432
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• 2003

The technical combination of RP and RT has a potential for rapid manufacturing of three-dimensional parts. In the present work a new RP system, $VLM-_{ST}$, is proposed to manufacture net shapes of 3D prototypes. ㅁ human head shape and a kob shape are manufactured by the $VLM-_{ST}$ apparatus. In addition, a new RT technology, which utilizes a RTV molding technique and a triple reverse process technique, is proposed to manufacture net shapes of 3D plastic parts using prototypes of $VLM-_{ST}$. A plastic part of the knob shape os produced by the proposed RT technology. The combination of the proposed RP and RT enables the manufacturing of a plastic knob within two days.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.169-175
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• 1994

This study attempts to develop a process which can produce three-dimensional shapes of metals directly from CAD data. Prototypes made from metals, can not only be used to test the mecchanical properties of the product, but also potentially become the actual die or product itself. The test-device of the process has been designed and manufactured. The laser scanning method using a scanning path schedule composed of circle and arc elements, scanning speed variation method and dwell method have been developed, which resist warping phenomenon and increase the adhesiveness between the layers. For the production of prototypes with pure iron powder, the optimal values of the principal process parameters have been determined, through which cross-shaped and twisted clover-shaped prototypes have been fabricated. In order to improve the strength of the prototype, the experimental studies of solid-phase sintering, and copper infiltration have been done.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.2 s.179
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• pp.181-190
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• 2006

In the industry, three-dimensional coloring has been needed for a realistic prototype. The Z-corporation developed a 3D printer which provides a three-dimensional colored prototype. However, the process cannot be adopted to models fabricated by other rapid prototyping processes. In addition, time and cost for manufacturing colored prototypes still remain to be improved. In this study, a new coloring process using an ink-jet head is proposed for color printing on a three-dimensional surface. Process parameters such as the angle and the distance between the ink-jet nozzle and the three-dimensional surface should be investigated through experiments. In order to minimize the distortion of a 2D image, the correction matrix according to the sloped angle is proposed and obtained by analysis of printing errors. An image on the doubly curved surface is printed so as to verify the proposed method. As a practical example, a helmet is chosen for printing images on the curved surface. The practical applicability of the correction matrix is then demonstrated by printing the character images on the surface of the helmet.

• Imaging Science in Dentistry
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• v.51 no.1
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• pp.41-47
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• 2021

Purpose: This study aimed to compare the accuracy of 3-dimensional(3D) printed models derived from multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) systems with different fields of view (FOVs). Materials and Methods: Five human dry mandibles were used to assess the accuracy of reconstructions of anatomical landmarks, bone defects, and intra-socket dimensions by 3D printers. The measurements were made on dry mandibles using a digital caliper (gold standard). The mandibles then underwent MDCT imaging. In addition, CBCT images were obtained using Cranex 3D and NewTom 3G scanners with 2 different FOVs. The images were transferred to two 3D printers, and the digital light processing (DLP) and fused deposition modeling (FDM) techniques were used to fabricate the 3D models, respectively. The same measurements were also made on the fabricated prototypes. The values measured on the 3D models were compared with the actual values, and the differences were analyzed using the paired t-test. Results: The landmarks measured on prototypes fabricated using the FDM and DLP techniques based on all 4 imaging systems showed differences from the gold standard. No significant differences were noted between the FDM and DLP techniques. Conclusion: The 3D printers were reliable systems for maxillofacial reconstruction. In this study, scanners with smaller voxels had the highest precision, and the DLP printer showed higher accuracy in reconstructing the maxillofacial landmarks. It seemed that 3D reconstructions of the anterior region were overestimated, while the reconstructions of intra-socket dimensions and implant holes were slightly underestimated.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.11
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• pp.96-102
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• 2019

Reverse engineering involves duplicating a physical part by measuring and analyzing its physical dimensions, features, and material properties. By combining reverse engineering with three-dimensional (3D) printing, engineers can simply fabricate and evaluate functional prototypes. This design methodology has been attracting increasing interest with the advent of the Fourth Industrial Revolution. In the present study, we apply reverse engineering and 3D printing technologies to evaluate a fabricated automotive inner ring prototype. Through 3D printing, inner rings of various densities were prepared. Their physical dimensions were measured with a 3D scanning system. Of our interest was the effect of inner ring density on the physical dimensions of the fabricated prototype. We compared the design dimensions and physical dimensions of the fabricated prototypes. The results revealed that even the 20% density of inner ring was effective for 3D printing in terms of satisfying the design requirements.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.884-889
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• 1994

In this work, rapid prototyping and three dimensional finite element analysis are simltaneously applied to design metal forming processes. Rapid prototyping is a new prototyping technology which producess three dimensional part models directly from CAD data and has been extensively applied to various manufacturing processes. There are many types of rapid prototyping systems due to their building principles and materials. In this work, Stereolithography Apparatus (SLA) which is the most widely-used rapid prototyping system is introduced to manufacture the die set. To prepare STL file generally, mesh data which are in describing the die surface in finite element analysis are translated so that rapid prototyping and finite element analysis are effectively connected. The die sets are manufactured using SLA prototypes, and matal forming experiments are carried out using them. Comparing experiments results with analyses, the processes can be predicted and designed successfully.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.10a
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• pp.190-194
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• 2001

The integration of rapid prototyping and tooling has the potential for the rapid net shape manufacturing of three-dimensional parts with geometrical complexity. In this study, a new rapid prototyping process, transfer type of Variable Lamination Manufacturing (VLM-ST), was proposed to manufacture net shape of 3-D prototypes. In order to examine the efficiency and applicability of the proposed process, various 3-D parts, such as a world-cup logo, and extruded cross and a knob shape, were fabricated on the apparatus. In addition, the new rapid tooling process, which is a triple reverse process, was proposed to manufacture of 3-D functional part using VLM-ST prototypes and the plastic part of the knob shape was produced by the new rapid tooling process.

• Journal of Mechanical Science and Technology
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• v.20 no.1
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• pp.85-93
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• 2006

The trend of miniaturization has been applied to the research of rockets to develop prototypes of micro rockets. In this paper, the development of a web-integrated prototyping system for three-dimensional micro rockets, and the results of combustion tests are discussed. The body of rocket was made of 6061 aluminum cylinder by lathe process. The three-dimensional micro nozzles were fabricated on the same aluminum by using micro endmills with ${\phi}100{\mu}m{sim}{\phi}500{\mu}m$ diameter. Two types of micro nozzle were fabricated and compared for performance. The total mass of the rockets was 7.32 g and that of propellant (gun powder) was 0.65 g. The thrust-to-weight ratio was between 1.58 and 1.74, and the flight test with 45 degree launch angle from the ground resulted in $46\;m{\sim}53\;m$ of horizontal flight distance. In addition, ABS housing for the micro machined rocket was fabricated using Fused Deposition Modeling (FDM). A web-based design, fabrication, and test system for micro nozzles was proposed to integrate the distributed hardware resources. Test data was sent to the designer via the same web server for the faster feedback to the rocket designer.