• 한국정밀공학회지
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• 제25권3호
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• pp.157-164
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• 2008

While developing physical prototype from CAD model, rapid prototyping mainly focuses on two key points reducing time and material consumption. So, we have to change from a traditional solid model to building a hollowed prototype. In this paper, a new method is presented to hollow out solid objects with uniform wall thickness to increase RP efficiency. To achieve uniform wall thickness, it is necessary to generate internal contour by slicing the offset model of an STL model. Due to many difficulties in this method, this paper proposes a new algorithm that computes internal contours computing offset model which is generated from external contour using wall thickness. Proposed method can easily compute the internal contour by slicing the offset surface defined by the sum of circle swept volumes of external contours without actual offset and the circle wept volumes. Internal contour existences are confirmed by using the external point. Presented algorithm uses the 2D geometric algorithm allowing RP implementation more efficient. Various examples have been tested with implementation of the algorithm, and some examples are presented for illustration.

• 한국정밀공학회지
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• 제29권1호
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• pp.33-40
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• 2012

The scaffold serves as 3D substrate for the cells adhesion and mechanical support for the newly grown tissue by maintaining the 3D structure for the regeneration of tissue and organ. In this paper, we proposed integrated scaffold fabrication system using multi-axis rapid prototyping (RP) technology. It can fabricate various types of scaffolds: arbitrary sculptured shape, primitive shape, and tube shape scaffolds by layered dispensing biocompatible/ biodegradable polymer strands in designated patterns. In order to fabricate the 3D scaffold, we need to generate the plotting path way for the scaffold fabrication system. We design a data processing program - scaffold plotting software, which can convert the 3D STL file, primitive and tube model images into the NC code for the system. Finally, we fabricated the customized 3D scaffolds with high accuracy using the plotting software and the fabrication system.

• 한국실내디자인학회논문집
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• 제17권2호
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• pp.150-161
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• 2008

It requires more close cooperation process and mediator for smooth communication in this industry structure where design and engineers are separated. The database of design integrates separate system and helps connection between organizations. The application category is utilized variously from formation to operation. Architectures addressed in this content as Frank Gehry and Nox are making differentiated design on the base of 3d digital methodology and using it widely from generation to fabrication. Especially they got to be free from the generative limit as it became available to analyse, digital surface organization, and realize the complex system form. Now more integrated and delicate works got to be affordable owing to various kinds of improved CNC, RP(rapid-prototype) machines, and architecture hardwares. With a linkage of software now at their disposal, architects can create a digital model of a building and all of its design elements, and in turn use this 3d information to construct actual building components using machines driven by CNC and other advanced manufacturing techniques. Digital technologies are enabling a direct correlation between what design and construction, thus bringing to the forefront the issue of the significance of information, the production, communication, application, and control of digital information in the industrial system. The central requirement is the clear, reliable, and consistent exchange of information among all parties involved in creating a given project.

• 한국CDE학회논문집
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• 제3권3호
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• pp.201-209
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• 1998

To develop timely an optimal fan, a design system and a new manufacturing process used step by step have to be integrated. A small sized optimal fan for refrigerators, that was the goal on this project, was developed by the following principal processes. All processes are technologically linked in many directions: The existing fan was measured through reverse engineering. The measured data was used for the basic source of 3D design. The performance tests were carried and used as the data for the evaluation of the existing fan. Flow analysis by FANS-3D/sup [1]/ was performed at the given information (pressure drop and flow rate) to find out the configuration of optimal fan design. The flow patterns were investigated to measure the performance of fan through numerical experiment. The grid point data obtained by the above analysis turned into 3D high efficiency fan model by using CATIA. The product was manufactured by RP process (SLS, SLA) and tested the characteristic curves of the developed fan to compare with the existing fan. The modification of fan design were all examined to see any change in performance and checked to find any deficiency in assembling the fan into a duct. After the plastics flow analysis of the injection molding cycle to ensure acceptable quality fan, an optimal mold was processed by using tool-path for the newly designed fan.

• 전자공학회논문지D
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• 제34D권5호
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• pp.32-44
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• 1997

A three-dimensional (3D) full-dynamic damage model for ion implantation in crystalline silicon was proposed to calculate more accurately point defect distributions and ion-implanted concentration profiles during ion implantation process. The developed model was based on the physical monte carlo approach. This model was applied to simulate B and BF2 implantation. We compared our results for damage distributions with those of the analytical kinchin-pease approach. In our result, the point defect distributions obtained by our new model are less than those of kinchin-pease approach, and the vacancy distributions differ from the interstitial distributions. The vacancy concentrations are higher than the interstitial ones before 0.8 . Rp to the silicon surface, and after the 0.8 . Rp to the silicon bulk, the interstitial concentrations are revesrsely higher than the vacancy ones.The fully-dynamic damage model for the accumulative damage during ion implantation follows all of the trajectories of both ions and recoiled silicons and, concurrently, the cumulative damage effect on the ions and the recoiled silicons are considered dynamically by introducing the distributon probability of the point defect. In addition, the self-annealing effect of the vacancy-interstitial recombination during ion implantation at room temperature is considered, which resulted in the saturation level for the damage distribution.

• 한국정밀공학회지
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• 제24권6호
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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.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1999년도 춘계학술대회 논문집
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• pp.81-86
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• 1999

The STL file format is an approximation of 3-D model with triangular facets. STL is a standard input file format of Rapid Prototyping(RP) equipment. In computer graphics, a circle has been approximated with an inscribed polygon, which causes an error between the real and approximated circles. In this study, an intersecting polygon has been used to approximate the circle and applied to produce more accurate RP part. The newly proposed method shows it's excellence in part accuracy.

• Journal of International Society for Simulation Surgery
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• 제3권1호
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• pp.36-38
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• 2016

Fibrous dysplasia is a relatively rare disease but the management would be quite challenging. Because this is not a malignant tumor, the preservation of the facial contour and the various functions seems to be important in treatment planning. Until now the facial bone reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for facial bone reconstruction, donor site morbidity would be the inevitable problem in many cases. Meanwhile, various types of allogenic and alloplastic materials have been also used. However, facial bone reconstruction with many alloplastic material have produced no less complications including infection, exposure, and delayed wound healing. Because the 3D printing technique evolved so fast that 3D printed titanium implant were possible recently. The aim of this trial is to try to restore the original maxillary anatomy as possible using the 3D printing model, based on the mirrored three dimensional CT images based on the computer simulation. Preoperative computed tomography (CT) data were processed for the patient and a rapid prototyping (RP) model was produced. At the same time, the uninjured side was mirrored and superimposed onto the traumatized side, to create a mirror-image of the RP model. And we molded Titanium mesh to reconstruct three-dimensional maxillary structure during the operation. This prefabricated Titanium-mesh implant was then inserted onto the defected maxilla and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be successful in this patient. Individualized approach for each patient could be an ideal way to restore the facial bone.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2002년도 춘계학술발표논문집(하)
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• pp.901-906
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• 2002

본 논문은 신속조형(RP: rapid prototyping) 시스템에서 사용되며 3D 기하학적 형상 모델을 가지고 있는 STL(standard transform language)에 워터마크를 삽입하는 방법에 관한 연구이다. 제안된 알고리즘은 3D 형상 데이터의 왜곡이 전혀 없이 패싯(facet, mesh)의 버텍스(vertex) 영역에 워터마크를 삽입한다. 기존의 알고리즘으로 STL에 워터마크를 삽입할 경우, 패싯의 저장순서를 변경하는 단순한 공격으로도 워터마크가 제거된다. 제안된 알고리즘은 패싯의 저장 순서 변경과 같은 공격에 대한 강인성을 가질 뿐만 아니라, 비가시성(invisibility)도 충족한다. 제안된 알고리즘으로 STL 3D 형상에 워터마크를 삽입하고 추출하는, 실험 결과들은 3D 원형상을 전혀 왜곡하지 않고 워터마크의 삽입과 추출이 가능함을 보여준다.

• Journal of International Society for Simulation Surgery
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• 제3권1호
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• pp.12-15
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• 2016

Functional and esthetic reconstruction after segmental mandibulectomy is one of the most challenging surgeries in microsurgical reconstruction field. Simulation surgery before free flap reconstruction has been performed for efficient surgery and successful results. Fibula free flap is the flap of the choice for reconstruction of the segmental mandibular defect. Straight nature of the fibula bone requires multiple segmentations to fit into mandible. 3D rapid prototype (RP) model gives a lot of information for mandibular reconstruction. The purpose of this study was to report mandibular reconstruction with free fibular flap using simulation surgery. A total of 30 consecutive patients were included for functional and esthetic evaluation. Among 30 patients, two flaps showed necrosis after radiotherapy. The other flaps were all survived and showed successful reconstruction in both function and esthetics.