• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1997년도 춘계학술대회 논문집
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• pp.150-155
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• 1997

Rapid Prototyping(RP) is the technique which is used to make prototypes or functional parts directly using the 3-D solid data. Before building the prototype, several processes such as transfering 3D data from CAD system(STL) determination of build-direction, adding support structure and slicing are required. Among the above processes. determination of build-direction is the target of this study. The build direction is determined by many factors according to the objective of the user, like part accuracy, number of support structure, build time, amount of trapped volume, etc, But it is not easy to determine the build-direction because there are many factors and some factors have dependent properties with one another. So, in this study the part accuracy, the number of support structures and build time are considered as the main factor to determine the optimal build-direction. To determine the optimal build-direction for increasing part accuracy, sum of projected area which caused stairstepping effect was considered. The less the projected area is the better part accuracy is About the optimal build-direction to minimize the amount of support structure, sum of projected area of facets that require support structures was considered. About the build time, we considered the minimum height of part we intended. About the build time, we considered the minimun height of part we intended to make.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.10-12
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• 2008

Hemodynamic features of blood flow in the abdominal aorta aneurysm (AAA) are very important, because they are closely related with the rupture of aneurysm to death. It has been considered that the wall shear stress of blood flows influences the formation, growth, and rupture of AAA. On this account, it is important to understand the flow structure of blood in the aneurysm. In this study, the whole velocity field information inside a typical AAA was measured using an in vitro AAA model under the pulsatile flow condition. The vessel geometry was reconstructed based on the computerized tomography (CT) data of a patient. The AAA model was made by using a rapid prototyping (RP) method, based on the reconstructed vessel geometry. Velocity fields in the AAA model were measured at different pulsatile phases using a PIV (particle image velocimetry) system. As experimental results, a large-scale vortex is formed inside the AAA model and the vortices located near the AAA wall are supposed to increase the local pressure and wall shear stress. In this study, the AAA wall stress found to be was one of the most important governing parameters giving rise to the ruptured aneurysm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.599-602
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• 2002

A novel rapid prototyping (RP) process, an automated transfer type variable lamination manufacturing process (Automated VLM-ST) has been developed. In Automated VLM-ST, a vacuum chuck and linear moving system transfer the plate type material with two pilot holes to the rotation stage. A four-axis synchronized hotwire cutter cuts the material twice to generate Automated Unit Shape Layer (AUSL) with the desired width, side slopes, length, and two reference shapes in accordance with CAD data. Each AUSL is stacked on the stacking plate with two pilot pins using the pilot holes in AUSL and the pilot pins. Subsequently, adhesive is supplied to the top surface of the stacked AUSL by a bonding roller and pressure is simultaneously applied to the bottom surface of the stacked AUSL. Finally, three-dimensional shapes are rapidly fabricated. This paper describes the procedure for generating the cutting path data (AUSL data) f3r automated VLM-ST. The method for the generation of the Automated Unit Shape Layer (AUSL) in Automated VLM-ST was practically applied and fabricated for a various shapes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.231-235
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• 2005

Most tissue engineering strategies for creating functional replacement tissues or organs rely on the application of temporary three-dimensional scaffolds to guide the proliferation and spread of seeded cells in vitro and in vivo. Scaffolds should be satisfied following requirements; macrostructure to promote cell proliferation, pore interconnectivity, pore size ranging from 200 to $400{\mu}m$, surface chemistry and mechanical properties. Rapid prototyping techniques have often been used as an useful process that fabricates scaffolds with complex structures. In this study, a new process to fabricate a three-dimensional scaffolds using bio-compatible polymer has been developed. It employs a highly accurate three-dimensional positioning system with pressure-controlled syringe to deposit biopolymer structures. The pressure-activated microsyringe is equipped with fine-bore nozzles of various inner-diameters. In order to examine relationships between line width and process parameters such as nozzle height, applied pressure, and speed of needle, experiments were carried out. Based on the experimental results, three-dimensional scaffold was fabricated using the apparatus. It shows the validity of the proposed process.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2170-2174
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• 2005

Selective Laser Sintering (SLS) is a useful rapid prototyping technique for the manufacture of three dimensional (3D) solid objects directly from a scanning data. A new approach called a Selective Multi-Laser Sintering (SMLS) system has been developed at Korea Institute Machinery & Materials (KIMM) as an industrial type SFFS. This SMLS machine is built with a frame, heaters, nitrogen supply part, laser system. This system uses the dual laser and 3D scanner made in $Solutionix^{TM}$ to improve the precision and speed for large objects. The three-dimensional solid objects are made of polyamide powder. The investigation on each part of SMLS system is performed to determine the proper theirs design and the effect of experimental parameters on making the 3D objects. The temperature of the system has a great influence on sintering the polymer. Because the stability of the powder temperature prevents the deformation of each layer, the controls of the temperature in both the system and the powders are very important during the process. Therefore, we simulated the temperature distribution of build room using the temperature analysis with ANSYS program. Selected radiant heater is used to raise temperature of powder to melting point temperature. The laser parameters such as scan spacing, scan speed, laser power and laser delay time affect the production the 3D objects too. The combination of the slow scan speed and the high laser power shows the good results without the layer curling. The work is under way to evaluate the effect of experimental parameters on process and to produce the various objects. We are going to experiment continuously to improve the size accuracy and surface roughness.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2001년도 춘계학술발표논문집
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• pp.307-311
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• 2001

신속조형시스템(RP : Rapid Prototyping)용 자료교환 표준인 STL의 자료구조는 단순하고, 조형용 2차원 단면 자료로의 전환이 용이하며, 생산 가공 기술로서의 현대적인 특성(신속성, 조형성, 경제성, 청정성 등)을 가지고 이는 장점이 있는 반면에, STL 3D 좌표값의 기준(좌표계의 원점)이 되는 크기 정보가 없다. 이런 문제를 구현된 STL 뷰어에서는, 스케일링(scaling) 기법과 선형적인 이동 기법을 사용하여 해결하였고, CAD 시스템으로 제작된 파일 자체의 문제점 패싯(facet) 중복, 정밀도, 법선 벡터 값의 오류 등도 검증기(verifier)와 오류 정정기(error corrector)글 구현하여 해결하였다. 제안된 방법으로 구현된 STL 뷰어는 시스템의 안정성과 확장성, 그리고 효율성 측면에서 우수한 성능을 보였으며, 슬라이싱(slicing), 경로 추적기(path tracer)의 전처리기의 역할을 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 합동 추계학술대회 논문집 정보 및 제어부문
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• pp.75-78
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• 2002

SFFS(Solid Freeform Fabrication System) is commercializing to rapid prototyping concept in world-wide some corporations including the States, have much technological problems yet and need new mode for agile solid freeform fabrication as well as prototyping. In this paper, we design an automatic control algorithm that the cutting path of laser beam, on the SFFS, is controlled with constant speed. The designed algorithm for constant-speed path control is implemented and experimented in the $CAFL^{VM}$ (Computer Aided Fabrication of Lamination for Various Material) system, the new SFFS which is developed in this paper. Its process is an automated fabrication method in which a 3D object is constructed from STL(SToreoLithography) 2D data, derived from CAD 3D image, by sequentially laminating the part cross-sections. The constant-speed path control is started from the STL data. After STL file is modified in data format to be available for control. The fabrication of the 2D part is, with constant speed, conducted from the 23 position data by laser beam. we confirm its high-performance through experiment results from the application into $CAFL^{VM}$ system.

• 대한기계학회논문집B
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• 제37권3호
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• pp.249-257
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• 2013

쾌속조형기술을 이용한 3차원 형상의 인공지지체가 조직공학 적용을 위해 개발되고 제작되었다. 본 연구에서는 폴리머 적층 시스템을 이용한 스캐폴드 제작에 있어 시린지 노즐 부분에 노즐 가이드를 장착하여 폴리머 적층 폭과 높이 실험을 수행하였다. 이 때 인공지지체 제작을 위한 생체재료로 폴리카프로락톤이 사용되었다. 폴리머 적층 공정 조건으로는 600 kPa의 공압과 $125^{\circ}C$의 온도가 이용되었다. 성공적인 와셔 인공지지체 제작을 통해 폴리머 적층 시스템에 적용된 노즐 가이드의 성능이 검증되었다. 결론적으로, 향상된 폴리머 적층 시스템을 이용함으로써 복잡한 형상의 조직공학용 3 차원 인공지지체를 제작할 수 있을 것으로 기대된다.

• 대한두개안면성형외과학회지
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• 제17권3호
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• pp.146-153
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• 2016

Background: Restoring the orbital cavity in large blow out fractures is a challenge for surgeons due to the anatomical complexity. This study evaluated the clinical outcomes and orbital volume after orbital wall fracture repair using a rapid prototyping (RP) technique and intraoperative navigation system. Methods: This prospective study was conducted on the medical records and radiology records of 12 patients who had undergone a unilateral blow out fracture reconstruction using a RP technique and an intraoperative navigation system from November 2014 to March 2015. The surgical results were assessed by an ophthalmic examination and a comparison of the preoperative and postoperative orbital volume ratio (OVR) values. Results: All patients had a successful treatment outcome without complications. Volumetric analysis revealed a significant decrease in the mean OVR from $1.0952{\pm}0.0662$ (ranging from 0.9917 to 1.2509) preoperatively to $0.9942{\pm}0.0427$ (ranging from 0.9394 to 1.0680) postoperatively. Conclusion: The application of a RP technique for the repair of orbital wall fractures is a useful tool that may help improve the clinical outcomes by understanding the individual anatomy, determining the operability, and restoring the orbital cavity volume through optimal implant positioning along with an intraoperative navigation system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.204-209
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• 1995

The implementation of rapid prototyping technologies has been developed for automotive engineering by utilizing concurrent engineering principes integrated with slective laser sintering. The Selective Laser Sintering, in which a part is generated in layers form powder using a computer-controlled laser scanning apparatus and power feed system. An over view of the basic principles of SLS Machine operation is given. Binding mechanisms are described for power which becomes thermally activated bye the scanning laser beam; viscous flow and melting of a low-melting-point phase in powder. The production of parts from metal is described, including post processing to improve structural integrity and induce a transformation.