• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.155-155
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• 2004

최근 집중 육성산업으로 분류되어 연구 및 투자가 되고 있는 반도체, 정보통신, 바이오산업, 디스플레이 등에서 초정밀화와 저비용, 대량생산을 하기 위해서 기존의 공정을 대체할 수 있는 새로운 나노공정기술의 요구가 급증하고 있다 최근에는 극초단파 특성으로 인하여 극미세 형상을 가공할 수 있는 펨토초 레이저(femto second laser)를 나노공정에 적용하는 다양한 연구가 진행되고 있다. 특히, 기존의 쾌속조형공정을 응용하여 다른 공정으로는 제작이 불가능한 나노 스케일에서 3차원 자유곡면을 가지는 구조물을 제작할 수 있는 공정개발에 대하여 다양한 연구가 진행되고 있다.(중략)

• Journal of the Korean Society for Precision Engineering
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• v.19 no.2
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• pp.95-105
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• 2002

In order to reduce the lead-time and cost, the technology of rapid prototyping (RP) has been widely used. However, RP technologies have disadvantageous characteristics according to their working principle: low building speed, high cost for introduction and maintenance of RP apparatus, stair-stepped surface and additional post processing. A new rapid prototyping process, as a transfer type of Variable Lamination Manufacturing by using expandable polystyrene room (VLM-ST), has been developed to reduce building lime. apparatus cost including the introduction and the maintenance and additional post-processing. The objective of this study is to propose a VLM-ST process and to develop an apparatus for implementation of the process. Design criteria of the apparatus are defined and the techniques arc proposed to satisfy the design criterion. In order to examine the efficiency and applicability of the developed process, various three-dimensional shapes, such as a world-cup logo. a knob shape, an extruded cross, a twisted shape, a character, Son-o-kong. a helical gear shaped and a scissor shape are fabricated on the apparatus in which unit shape layer (USL) was generated to build up each layer.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.187-190
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• 2007

The objective of this paper is to investigate into the development of injection mould with high cooling characteristics using a direct metal RP technology. In order to manufacture the injection mould with a high cooling rate, three-dimensional conformal cooling channels have been generated in the mould. DMT process, which is one of direct metal RP technologies, has been utilized to directly manufacture the metallic mould with three-dimensional conformal cooling channels. In order to examine the performance of the designed mould, injection molding tests have been carried out. The results of the experiments have been shown that a cooling time and the injection time of the proposed mould are reduced by the factor of five and two times in comparison with the injection mould with linear cooling channels.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.2 no.3
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• pp.5-12
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• 2003

In order to reduce the lead-time and cost, many useful methods have been applied to rapid prototyping (RP) in recent years. But cutting process is still considered as one of the effective RP methods that have been developed and currently available in the industry. It also offers practical advantages in aspects of precision and versatility. However, traditional 3-axis NC machining has some inherent limitations such as the restriction of tool accessibility and the complex setup. In this work, a new rapid prototyping system with high speed 5-axis machining of plastics has been developed to overcome those limitations. And cutting experiments were conducted to determine the design factors of the system and the cutting conditions of plastics. The architecture of developed system is described in detail and the successful application examples are presented.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.37-40
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• 2001

This paper describes the selection and evaluation of RP processes. Major rapid prototyping processes such as SLS, SLA, FDM and LOM, which are wide spread in use are selected. A test part, which includes various primitives, is designed in order to evaluate these RP processes. Measurement of the test part is automated by using a CMN program. To visualize and analyze measured data, Microsoft Access and Visual C++ are used. Also, from measured data obtained, TOPSIS, one of the decision making methods, and Shannon Entropy is used to select an appropriate RP process for specific application.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.1047-1050
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• 1997

Rapid Prototyping(RP) is an efficient method for rapid design verification and trial manufacturing. In order to improve their unique characteristics according to the working principles. Variable Lamination Manufacturing process and corresponding CAD/CAM system is developed. The objective of this study is to improve dimensional accuracy of VLM-ST process, and it can be done by offset for cutting error correction, cutting path correction for sharp edge and reference shape generation. To verify the proposed algorithms, they applied to three-dimensional shapes, such as spanner and mechanical part.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.22-25
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• 2003

It is usually difficult for a single user to have all the essential knowledge on various Rapid Prototyping processes and techniques. It is therefore necessary to capture knowledge and experience of users of expert level into a decision-support system which provides quicker and more interactive way to select proper RP process and/or machine. rather than reading reports on benchmarking studies and comparing tables and graphs. In this paper two algorithms are presented, which may be used in such a decision-support system. together with its applications. The one is an extended PRES(Project Evaluation and Selection) algorithm which applies weighting factors of each attribute. The other is a LCE(Linear Confidence Equation) algorithm which is proposed to apply user's input requirements as well as weighting factors.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.131-137
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• 2007

In metal casting process, it is very difficult to predict the form accuracy of cast part and reduce repeatability error. In this study, the variations of form accuracy were measured in the process of metal cast prototyping, where RP part is manufactured from CAD model in the first, and then, wax part is cast in the vacuum environment using the RP part as master model, and finally metal prototype is cast using ceramic mold and the wax part as pattern. To investigate the variations of form accuracy, the averages and standard deviations of error distribution of the parts measured by 3D scanner were compared. It was observed that the biggest shrinkage is generated during the extraction of wax part in the second step and the biggest deterioration of form accuracy is generated during the metal part casting in the last step.

• Journal of the Korean Society for Precision Engineering
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• v.24 no.6
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• pp.138-145
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• 2007

Among various rapid prototyping processes, stereo-lithography process which can manufacture transparent prototype is known to be the greatest in the form & dimensional accuracy and surface roughness. In this paper, bench mark tests of 4 stereo-lithography-type rapid prototyping apparatus were carried out using transparent materials. The test includes measurement of mechanical properties, form accuracy, building speed and manufacturing cost. It was observed that ViperPRO of 3D systems is advantageous in the mechanical properties and building speed, RM600011 of CMET in sub-milli scale form accuracy and manufacturing cost, and relatively economical Eden500V of Objet is great in tensile strength at room temperature.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.12
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• pp.1958-1967
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• 2004

This paper describes the method to rapidly fabricate the large-sized physical model with the envelope model size of more than 600 mm${\times}$ 600 mm${\times}$ 600 mm using two type semi-automatic VLM-ST processes in connection with the reverse engineering technology. The fabrication procedure of the large-sized solid shape is as follows: (1) Generation of STL data from 3D scan data using 3D scanner, (2) generation of shell-type STL data by Boolean operation, (3) division of shell-type STL data into several pieces by solid splitting, (4) generation of USL data for each piece with VLM-Slicer, (5) fabrication of each piece by cutting and stacking according to USL data using VLM-ST apparatus, (6) completion of a shell-type prototype by zigzag stacking and assembly for each piece, (7) completion of a 3D solid shape by foam backing, (8) surface finish of a completed 3D solid shape by coating and sanding. In order to examine the applicability of the proposed method, the miniature of the Mount Rushmore Memorial has been fabricated. The envelope model size of the miniature of the Mount Rushmore Memorial is 1,453 mm${\times}$ 760 mm${\times}$ 853 mm in size. From the result of the fabricated miniature of the Mount Rushmore Memorial, it has been shown that the method to fabricate the large object using two type semi-automatic VLM-ST processes in connection with the reverse engineering technology are very fast and efficient.