• Journal of International Society for Simulation Surgery
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• v.1 no.1
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• pp.16-18
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• 2014

The orbit has a very special anatomical structure. The complex anatomical structure should be restored when we encounter the patient with orbital wall fracture. Unless these specific anatomy were reconstructed well, the patient should suffer from various complications such enophthalmos, diplopia or orbital deformity. In addition, because the patient has a his own specific orbital shape, individualized approach will be necessary. The aim of this trial is to try to restore the original orbit anatomy as possible 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. In order to restore the missing skipped images between the cuts of CT data because of the thinness of the orbital walls, we manipulated the DICOM data for imaging the original orbital contour using the preoperatively manufactured mirror-image of the RP model. And we fabricated Titanium-Medpor to reconstruct three-dimensional orbital structure intraoperatively. This prefabricated Titanium-Medpor was then inserted onto the defected orbital wall and fixed. Three dimensional approach based on the computer simulation turned out to be very successful in this patient. Individualized approach for each patient could be an ideal way to manage the traumatic patients in near future.

• Journal of International Society for Simulation Surgery
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• v.1 no.2
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• pp.99-102
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• 2014

The skull defect can be made after the trauma, oncologic problems or neurosurgery. The skull reconstruction has been the challenging issue in craniofacial fields for a long time. So far the skull reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for skull 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, skull 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 skull anatomy as possible using the 3D printed titanium implant, 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 fabricated Titanium implant to reconstruct three-dimensional orbital structure in advance, using the 3D printer. This prefabricated Titanium-implant was then inserted onto the defected skull and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be very successful in this patient. Individualized approach for each patient could be an ideal way to manage the traumatic patients in near future.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.9 s.180
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• pp.2235-2245
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• 2000

The necessity of using rapid prototyping(RP) for short-run manufacturing is continuously driving a development of a cost-effective technique that will produce completely-finished quality parts in a very short time. To meet these demands, the improvements in production speed, accuracy, materials, aid cost are crucial. Thus, a new hybrid-RP system performing both deposition and machining in a station is proposed. For the new hybrid RP process to maintain the same degree of process automation as in currently available processes like SLA or FDNI, a sophisticated process planning system is developed. In the process planner, CAD models(STEP AP203) are partitioned into 3D manufacturable volumes called 'Ueposition feature segment"(DFS) after machining features called "machining feature segmenf'(MFS) are extracted from the initial CAD model. Once MFS and DFS are identified, the process planner arranges them into a chain of processes and automatically generates machining information for each DFS and MFS. The goal of this paper is to present a framework for a process planning system for hybrid RP processes and to outline the geometric algorithms involved in developing such an environment.

• The korean journal of orthodontics
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• v.44 no.2
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• pp.69-76
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• 2014

Objective: This study aimed to evaluate the accuracy and precision of polyurethane (PUT) dental arch models fabricated using a three-dimensional (3D) subtractive rapid prototyping (RP) method with an intraoral scanning technique by comparing linear measurements obtained from PUT models and conventional plaster models. Methods: Ten plaster models were duplicated using a selected standard master model and conventional impression, and 10 PUT models were duplicated using the 3D subtractive RP technique with an oral scanner. Six linear measurements were evaluated in terms of x, y, and z-axes using a non-contact white light scanner. Accuracy was assessed using mean differences between two measurements, and precision was examined using four quantitative methods and the Bland-Altman graphical method. Repeatability was evaluated in terms of intra-examiner variability, and reproducibility was assessed in terms of interexaminer and inter-method variability. Results: The mean difference between plaster models and PUT models ranged from 0.07 mm to 0.33 mm. Relative measurement errors ranged from 2.2% to 7.6% and intraclass correlation coefficients ranged from 0.93 to 0.96, when comparing plaster models and PUT models. The Bland-Altman plot showed good agreement. Conclusions: The accuracy and precision of PUT dental models for evaluating the performance of oral scanner and subtractive RP technology was acceptable. Because of the recent improvements in block material and computerized numeric control milling machines, the subtractive RP method may be a good choice for dental arch models.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.6
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• pp.131-142
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• 2007

In this paper, semi-fragile watermarking algorithm was proposed for the application to RP(Rapid Prototyping) system. In the case of the perceptual change or distortion of the original one, the prototype product will be affected from the process because the RP system requires the high precision measure. Therefore, the geometrical transformations like translation, rotation and scaling, the mesh order change and the file format change are used in the RP system because they do not change the basic shapes of the 3D models, but, the decimation and the smoothing are not used because they change the models. The proposed algorithm which is called semi-fragile watermarking is robust against to these kinds of manipulations which preserve the original shapes because it considers the limitations of the RP system, but fragile against to the other manipulations which change the original shapes. This algorithm does not change the model shapes after embedding the watermark information, that is, there is no shape difference between the original model and the watermarked model. so, it will be useful to authenticate the data integrity and hide the information in the field of mechanical engineering which requires the high precision measure.

• Journal of the Korean Society of Visualization
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• v.10 no.1
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• pp.55-59
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• 2012

Reverse Design(RD) plays an important role in simulation engineering, such as CFD (Computational Fluid Dynamics) and Virtual Engineering and Design. RD becomes much more valuable when there is no shape data of the practical models for CFD grid generations. In this study, two-camera based rapid prototyping(RP) system is proposed. 3D-PTV based measurement algorithm was adopted. The developed system was applied to reconstruct three-dimensional data of a human face, a motorcycle model, a cylindrical body and a triangular pyramid.

• Journal of Korea Foundry Society
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• v.21 no.5
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• pp.290-295
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• 2001

We fabricated test samples containing various shape elements and surface roughness checking points for the jewelry cast master patterns by employing the 3D computer aided design (CAD), selective laser sintering (SLS) rapid prototype (RP) with the DuraForm powders. We varied the alignment angle from $0^{\circ}$ to $10^{\circ}$ at a given layer thickness of 0.08 and 0.1mm, respectively, in RP operation. Dimensions of the shape elements as well as values of surface roughness are characterized by an optical microscope and a contact-scanning profilometer. Surface roughness values of the top and vertical face increased as the alignment angle increased, while the other roughness values and shape elements variation were not depending on the alignment angle. The resolution of the shape realization was enhanced as the layer thickness became smaller. The minimum diameter of the hole, common in jewelry design, was 1.2 mm, and the shrinkage became 12% at the 1.6 mm-diameter hole, Our results implied that we face down the proposed design elements with $0^{\circ}$ alignment angle, and consider the shrinkage effect of each shape element in DuraForm RP jewelry modeling.

• Bulletin of the Korean Chemical Society
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• v.33 no.4
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• pp.1123-1127
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• 2012

P-gp (P-glycoprotein) is a member of the ATP binding cassette (ABC) family of transporters. It transports many kinds of anticancer drugs out of the cell. It plays a major role as a cause of multidrug resistance (MDR). MDR function may be a cause of the failure of chemotherapy in cancer and influence pharmacokinetic properties of many drugs. Hence classification of candidate drugs as substrates or nonsubstrate of the P-gp is important in drug development. Therefore to identify whether a compound is a P-gp substrate or not, in silico method is promising. Recursive Partitioning (RP) method was explored for prediction of P-gp substrate. A set of 261 compounds, including 146 substrates and 115 nonsubstrates of P-gp, was used to training and validation. Using molecular descriptors that we can interpret their own meaning, we have established two models for prediction of P-gp substrates. In the first model, we chose only 6 descriptors which have simple physical meaning. In the training set, the overall predictability of our model is 78.95%. In case of test set, overall predictability is 69.23%. Second model with 2D and 3D descriptors shows a little better predictability (overall predictability of training set is 79.29%, test set is 79.37%), the second model with 2D and 3D descriptors shows better discriminating power than first model with only 2D descriptors. This approach will be used to reduce the number of compounds required to be run in the P-gp efflux assay.

• Journal of International Society for Simulation Surgery
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• v.1 no.2
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• pp.90-94
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• 2014

Reconstruction of the mandible after ablative oral cancer surgery requires esthetic and functional rehabilitation. Restoring facial symmetry and dentition need accurate preoperative surgical planning and meticulous surgical technique. Free fibular flap is most useful tools to reconstruct mandible because of its adequate length and height, simultaneous harvest of soft and hard tissues and placing dental implants. In this case report, recurred squamous cell carcinoma in the right mandible had been resected and free fibular flap was utilized for mandible reconstruction using 3D rapid prototype. Simulation surgery before dental implant placement has been performed for esthetic and functional prosthodontics.

• Journal of International Society for Simulation Surgery
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• v.3 no.2
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• pp.77-79
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• 2016

Osteoma is one of the benign tumor that occurs on the bones all over the body. Mostly the simple excision is known to be enough. However, sometimes we encounter the troublesome situation where the osteoma is located in very challenging area, which results in the recurrence. 26 year female presented with the intractable intracranial osteoma. Given the disease entity of the osteoma, the simple excision would be enough or conservative management. But this osteoma turned out to be huge and recurrent in spite of the endoscopic resections, which causes the facial disappearance accompanied by the orbital vertical dystopia. Moreover, the patient's main concern was the pain. We performed the intracranial resection of the whole lesion and reconstructed the skull base and frontal bone as well as the part of the orbital wall. In order to restore the original bony anatomy, the 3D printing model was used based on the titanium mesh. I report this unusual case of the intractable intracranial huge osteoma. This report may be helpful for the other surgeons to make a decision on their similar cases in the future.