• Journal of Technologic Dentistry
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• v.43 no.3
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• pp.77-83
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• 2021

Purpose: The purpose of this in vitro study was to measure and compare the thickness-dependent color dimensions of digital light processing (DLP) three-dimensional (3D) printer and conventional interim restorative resin. Methods: Specimens (N=60) were fabricated using either subtractive manufacturing (S group) or DLP 3D printing (D group) material. All milled and 3D-printed specimens were allocated into three different groups (n=10) according to different thicknesses as follows: 1.0, 1.5, and 2.0 mm. Color measurements in the CIELab coordinates were made using a spectrophotometer under room light conditions (1,003 lux). The color differences (𝚫E^*) between the specimen and control target data were calculated. Data were analyzed using the oneway analysis of variance (ANOVA). Post hoc comparisons were conducted using Tukey's honestly significant difference method (α=0.05 for all tests). Results: The 𝚫L^*, 𝚫a^*, 𝚫b^*, and 𝚫E^* values of interim restorative resin produced by DLP 3D printing were obtained in terms of the specimen's thickness increased compared with the increases by subtractive manufacturing. When the thickness was similar, the color difference between subtractive manufacturing and DLP 3D printing was ≥5.5, which is a value required by the dentist for remanufacturing. Conclusion: Color was influenced by the thickness of the interim restorative resin produced by DLP 3D printing.

• The Journal of Advanced Prosthodontics
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• v.8 no.3
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• pp.219-223
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• 2016

PURPOSE. This study aimed to create a digitized database of fabricated obturators to be kept for patients' potential emergency needs. MATERIALS AND METHODS. A chairside intraoral scanner was used to scan the surfaces of an acrylic resin obturator. The scanned data was recorded and saved as a single standard tessellation language file using a three-dimensional modeling software. A simulated obturator model was manufactured using fused deposition modeling technique in a three-dimensional printer. RESULTS. The entire obturator was successfully scanned regardless of its structural complexity, modeled as three-dimensional data, and stored in the digital system of our clinic at a relatively small size (19.6 MB). A simulated obturator model was then accurately manufactured from these data. CONCLUSION. This study provides a proof-of-concept for the use of digital technology to create a digitized database of obturators for edentulous maxillectomy patients.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.41 no.5
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• pp.225-233
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• 2004

A novel real-time color gamut mapping method is described. The color gamut mapping method that is used for enhancing the color reproduction quality between PC monitor and printer devices is adopted for digital TV display quality enhancement. The high definition digital TV display devices operate at the clock speed of around 70MHz ～ 150MHz and permit several nano seconds for real-time gamut mapping. Thus, the concept of three-dimensional reduced resolution look-up table is introduced for real-time processing. The required hardware can be greatly reduced by look-up table resolution adjustment. The proposed hardware architecture is successfully implemented in FPGA and ASIC and also successfully adopted in digital TV display quality enhancement purposes.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.988-991
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• 2015

3D printing technology is instrument that can create real objects in three-dimensional space, as printed on paper, if the three-dimensional designs are made. 3D printing technology has been recently used in various field of medicine, and also biomedical application of three dimensional printing technology remains one of the most important research topics until now. 3D printing technology is causing a revolutionary change in the overall automotive manufacturing, aerospace, marine, medical and so on. The medical industry applications of current 3D printer are a virtual simulation, custom medical implants manufactured, practice of medical personnel. In this study, we analyzed 3D printing technology and application cases for medical services.

• Journal of the Korea Furniture Society
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• v.27 no.2
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• pp.128-136
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• 2016

Digital designs that appear in the three-dimensional virtual space by the digital type are designed as there is not an image created with an organic artificially generated (Creation) and representation (Modifying), developed by the specific environment given. The advanced digital design will produce a result with an algorithm according to a mathematical operation and the environment and has the nature of generating the real world, changes, development and affinity (Genetic Process). The digital design process is largely defined by a set of processes that are consistently designed to integrate form of creation, reproduction, proceeds in three steps, while the manufacture and assembly as a form of maintenance as possible the intended form of control data from the concept of building. By Joris Laarman 3D printer design is a simulation created by the digital process by the various algorithms and design achieved through the development of 3D printers, such as new materials and MX3D. From the mold production of a complex whole by using a robot and other digital production tool extracts a variety of forms.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.879-886
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• 2018

A 3-dimensional (D) printer is a device capable of outputting a three-dimensional solid object based on data modeled in a computer. These features are utilized in the bone model X - ray phantom production etc using CT data by fusing with the radiation science field. A bone model phantom was made using data obtained by CT scan of an existing Pelvis phantom, using PLA, Wood, XT-CF20, Glow fill, Steel filaments which are materials of Fused Filament Fabrication (FFF) 3D printer.Measure Hounsfield Unit (HU) with images obtained by CT scan of the existing Pelvis phantom and five material phantoms made with 3D printer under the same conditions,SI and SNR were measured using a diagnostic X-ray generator, and each phantom was compared and analyzed.As a result, the X - ray phantom in the X - ray examination condition of the limb was found to be most suitable for the glow fill filament.The characteristics of the filament can be known to the base of this research and the practicality of X - ray phantom fabrication was confirmed.

• 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.

• Journal of Korean Neurosurgical Society
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• v.52 no.6
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• pp.541-546
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• 2012

Objective : The prefabrication of customized cranioplastic implants has been introduced to overcome the difficulties of intra-operative implant molding. The authors present a new technique, which consists of the prefabrication of implant molds using three-dimensional (3D) printers and polymethyl-methacrylate (PMMA) casting. Methods : A total of 16 patients with large skull defects (>100 $cm^2$) underwent cranioplasty between November 2009 and April 2011. For unilateral cranial defects, 3D images of the skull were obtained from preoperative axial 1-mm spiral computed tomography (CT) scans. The image of the implant was generated by a digital subtraction mirror-imaging process using the normal side of the cranium as a model. For bilateral cranial defects, precraniectomy routine spiral CT scan data were merged with postcraniectomy 3D CT images following a smoothing process. Prefabrication of the mold was performed by the 3D printer. Intraoperatively, the PMMA implant was created with the prefabricated mold, and fit into the cranial defect. Results : The median operation time was $184.36{\pm}26.07$ minutes. Postoperative CT scans showed excellent restoration of the symmetrical contours and curvature of the cranium in all cases. The median follow-up period was 23 months (range, 14-28 months). Postoperative infection was developed in one case (6.2%) who had an open wound defect previously. Conclusion : Customized cranioplasty PMMA implants using 3D printer may be a useful technique for the reconstruction of various cranial defects.

• Journal of Radiation Protection and Research
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• v.49 no.2
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• pp.68-77
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• 2024

Background: Cone beam computed tomography (CBCT) is essential for correcting and verifying patient position before radiation therapy. However, it poses additional radiation exposure during CBCT scans. Therefore, this study aimed to evaluate radiological safety for the human body through dose assessment for CBCT. Materials and Methods: For CBCT dose assessment, the depth dose was evaluated using a cheese phantom, and the dose in the orbital area was evaluated using a human body phantom self-fabricated with a three-dimensional printer. Results and Discussion: The evaluation of radiation doses revealed maximum doses of 14.14 mGy and minimum doses of 6.12 mGy for pelvic imaging conditions. For chest imaging conditions, the maximum doses were 4.82 mGy, and the minimum doses were 2.35 mGy. Head imaging conditions showed maximum doses of 1.46 mGy and minimum doses of 0.39 mGy. The eyeball doses using a human body phantom model averaged at 2.11 mGy on the left and 2.19 mGy on the right. The depth dose ranged between 0.39 mGy and 14.14 mGy, depending on the change in depth for each imaging mode, and the average dose in the orbit area using a human body phantom was 2.15 mGy. Conclusion: Based on the experimental results, CBCT did not significantly affect the radiation dose. However, it is important to maintain a minimal radiation dose to optimize radiation protection following the as low as reasonable achievable principle.

• Journal of Conservation Science
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• v.35 no.1
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• pp.71-80
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• 2019

This study examined the applicability of digital technologies based on three-dimensional(3D) scanning, modeling, and printing to the restoration of damaged artifacts. First, 3D close-range scanning was utilized to make a high-resolution polygon mesh model of a roof-end tile with a missing part, and a 3D virtual restoration of the missing part was conducted using a haptic interface. Furthermore, the virtual restoration model was printed out with a 3D printer using the material extrusion method and a PLA filament. Then, the additive structure of the printed output with a scanning electron microscope was observed and its shape accuracy was analyzed through 3D deviation analysis. It was discovered that the 3D printing output of the missing part has high dimensional accuracy and layer thickness, thus fitting extremely well with the fracture surface of the original roof-end tile. The convergence of digital virtual restoration based on 3D scanning and 3D printing technology has helped in minimizing contact with the artifact and broadening the choice of restoration materials significantly. In the future, if the efficiency of the virtual restoration modeling process is improved and the material stability of the printed output for the purpose of restoration is sufficiently verified, the usability of 3D digital technologies in cultural heritage restoration will increase.