• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.26 no.1
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• pp.100-107
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• 2017

3D printing is a technology that converts a computer-generated 3D model into a real object with additive manufacturing technology. A majority of 3D printing technologies uses one material, and this is considered a limitation. In this study, we developed a multi-material 3D printer by adopting dual resin vat and cleaning system with DLP (Digital Light Processing) 3D printing technology. The developed multi-material DLP 3D printer is composed of a manufacturing system, cleaning system, transporting system, and automatic resin recharging system. Various 3D structures were 3D printed with two materials, thus demonstrating the potential. Printing performance of the multi-material DLP 3D printer was studied by performing a comparative surface roughness test and tension test on specimens composed of one material as well as those composed of two materials.

• The Journal of Advanced Prosthodontics
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• v.13 no.2
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• pp.89-99
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• 2021

PURPOSE. This study aimed to compare the accuracy (trueness and precision) of interim crowns fabricated using DLP (digital light processing) according to post-curing time. MATERIALS AND METHODS. A virtual stone study die of the upper right first molar was created using a dental laboratory scanner. After designing interim crowns on the virtual study die and saving them as Standard Triangulated Language files, 30 interim crowns were fabricated using a DLP-type 3D printer. Additively manufactured interim crowns were post-cured using three different time conditions-10-minute post-curing interim crown (10-MPCI), 20-minute post-curing interim crown (20-MPCI), and 30-minute post-curing interim crown (30-MPCI) (n = 10 per group). The scan data of the external and intaglio surfaces were overlapped with reference crown data, and trueness was measured using the best-fit alignment method. In the external and intaglio surface groups (n = 45 per group), precision was measured using a combination formula exclusive to scan data (10C2). Significant differences in accuracy (trueness and precision) data were analyzed using the Kruskal-Wallis H test, and post hoc analysis was performed using the Mann-Whitney U test with Bonferroni correction (α=.05). RESULTS. In the 10-MPCI, 20-MPCI, and 30-MPCI groups, there was a statistically significant difference in the accuracy of the external and intaglio surfaces (P<.05). On the external and intaglio surfaces, the root mean square (RMS) values of trueness and precision were the lowest in the 10-MPCI group. CONCLUSION. Interim crowns with 10-minute post-curing showed high accuracy.

• Journal of Powder Materials
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• v.26 no.4
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• pp.327-333
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• 2019

In this study, a process is developed for 3D printing with alumina ($Al_2O_3$). First, a photocurable slurry made from nanoparticle $Al_2O_3$ powder is mixed with hexanediol diacrylate binder and phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide photoinitiator. The optimum solid content of $Al_2O_3$ is determined by measuring the rheological properties of the slurry. Then, green bodies of $Al_2O_3$ with different photoinitiator contents and UV exposure times are fabricated with a digital light processing (DLP) 3D printer. The dimensional accuracy of the printed $Al_2O_3$ green bodies and the number of defects are evaluated by carefully measuring the samples and imaging them with a scanning electron microscope. The optimum photoinitiator content and exposure time are 0.5 wt% and 0.8 s, respectively. These results show that $Al_2O_3$ products of various sizes and shapes can be fabricated by DLP 3D printing.

• Journal of the Korea Society of Computer and Information
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• v.14 no.12
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• pp.97-107
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• 2009

Television News has significant impact on the information analysis of viewers by delivering world news to anonymous individuals everyday. We need to pay more attention to resolution considering the fact that even slight facial expression and the dress of TV anchor can be noticed by viewers in the high definition age, called HD TV, by radical changes in broadcasting situation. As a result, the beauty of expression that lighting technology has is extremely important in the high definition age. In news broadcast, as a phenomenon according to this change in trend, people have been looking for change in order to break with traditional TV news production by adopting DLP(Digital Lighting Processing) or LED(Light Emitting Diode). This effort has contributed to creating proper picture quality appropriate for HD TV. Nowadays Digital imaging is creating new trend in TV news production method from traditional analog-based lighting environment thanks to the development of IT(Information Technology) and digitalized lighting equipment. This change has led to building of HD studio and appropriate sets and lighting system. There are film set and projector which projects image on the screen and PDP, LCD, and DLP which has been used widely in recent years and LED which is often used as background in news program as examples, which has appeared since 1990s with HD TV. In this article, I analyzed the KBS News 9 lnce 1990s with in order to research the influence of television image component on the alyzed the KBS of TV article, I. I wille uggest the category of TV anchor image formulation in delivering information by means of lnce 1990s with based on the analysis result.

• Journal of the Korea Convergence Society
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• v.10 no.4
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• pp.189-194
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• 2019

This thesis aimed to apply the 3D-printing technology rapidly introduced to the overall industry to jewelry design. In the results of examining preceding researches, out of 3D-printing methods, the FMD method was used the most in design area. However, for jewelry design, the 3D-printing is used for casting process out of production processes, so that the printing method is not FMD, but DLP. Thus, the researcher examined the material functions and applicability of jewelry design through research works, by applying the 3D-printing in DLP method to jewelry design. In the results, brooches were completed by applying the 3D-printing to the jewelry design with no casting process, and then utilizing enamel and pure silver together. Producing light and solid completed products in various colors, they were verified as applicable materials. Also, as the size and form of curved design mainly used for non-geometric jewelry design could be accurately predicted through Rhino CAD, diverse possibilities of advancement to be easily used for the development of formative form of jewelry design in the future were revealed.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08b
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• pp.1089-1092
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• 2007

New display technologies including LCD and plasma panels and Digital Light Projection (DLP) systems all offer large screens and impressive picture quality. However, flat-panel displays require a sophisticated picture processing to let these panels perform at their optimum levels. This paper explains why motion compensating techniques combined with frame rate conversion and quasi-impulse driving reduces motion blur and film judder for flat panel displays and presents the IC and its system application using this technique.

• Imaging Science in Dentistry
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• v.51 no.1
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• pp.41-47
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• 2021

Purpose: This study aimed to compare the accuracy of 3-dimensional(3D) printed models derived from multidetector computed tomography (MDCT) and cone-beam computed tomography (CBCT) systems with different fields of view (FOVs). Materials and Methods: Five human dry mandibles were used to assess the accuracy of reconstructions of anatomical landmarks, bone defects, and intra-socket dimensions by 3D printers. The measurements were made on dry mandibles using a digital caliper (gold standard). The mandibles then underwent MDCT imaging. In addition, CBCT images were obtained using Cranex 3D and NewTom 3G scanners with 2 different FOVs. The images were transferred to two 3D printers, and the digital light processing (DLP) and fused deposition modeling (FDM) techniques were used to fabricate the 3D models, respectively. The same measurements were also made on the fabricated prototypes. The values measured on the 3D models were compared with the actual values, and the differences were analyzed using the paired t-test. Results: The landmarks measured on prototypes fabricated using the FDM and DLP techniques based on all 4 imaging systems showed differences from the gold standard. No significant differences were noted between the FDM and DLP techniques. Conclusion: The 3D printers were reliable systems for maxillofacial reconstruction. In this study, scanners with smaller voxels had the highest precision, and the DLP printer showed higher accuracy in reconstructing the maxillofacial landmarks. It seemed that 3D reconstructions of the anterior region were overestimated, while the reconstructions of intra-socket dimensions and implant holes were slightly underestimated.

• Journal of Korean society of Dental Hygiene
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• v.19 no.6
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• pp.1089-1097
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• 2019

Objectives: The purpose of this study is to assess the accuracy of provisional restorative resins fabricated using dental three-dimensional (3D) printers. Methods: Provisional restorative resins were fabricated using the first molar of the right mandibular. Three groups comprising a total of 24 samples of such resins were fabricated. The prepared abutment was scanned initially and then designed using a computer-aided design (CAD) software. The conventional subtractive manufacturing system was employed to fabricate the first group of resins, while the second and third groups were fabricated using a digital light processing (DLP) 3D printer and a stereolithography (SLA) 3D printer, respectively. The internal surfaces of the resins were scanned and 3D measurements of the resins were taken to confirm their accuracy. Results: The root-mean-square deviation (RMS±SD) of the accuracy of the resins fabricated using the conventional subtractive manufacturing system, DLP 3D printer, and SLA 3D printer were 68.83±2.22 ㎛, 74.63±6.23 ㎛, and 61.74±4.09 ㎛, respectively. A one-way analysis of variance (ANOVA) test showed significant differences between the three groups (p < 0.05). Conclusions: Provisional restorative resins fabricated using DLP and SLA 3D printers demonstrated clinically-acceptable results.

• Korean Journal of Materials Research
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• v.31 no.9
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• pp.532-538
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• 2021

In this study, a spray dryer is used to make granules of Y₂O₃ and YF₃, and then Y₅O₄F₇ is synthesized following heat treatment of them under Ar gas atmosphere at 600 ℃. Single and binary monomer mixtures are compared and analyzed to optimize photocurable monomer system for DLP 3D printing. The mixture of HEA and TMPTA at 8:2 ratio exhibits the highest photocuring properties and low viscosity with shear thinning behavior. The optimized photocurable monomer and synthesized Y₅O₄F₇ are therefore mixed and applied to printing process at variable solid contents (60, 70, 80, & 85 wt.%) and light exposure times. Under optimal light exposure conditions (initial exposure time: 1.2 s, basic exposure time: 5 s), YOF composites at 60, 70 & 80 wt.% solid contents are successfully printed. As a result of measuring the size of the printed samples compared to the dimensions of the designed bar type specimen, the deviation is found to increase as the YOF solid content increases. This shows that it is necessary to maximize the photocuring activity of the monomer system and to optimize the exposure time when printing using a high-solids ceramic slurry.

• Journal of Technologic Dentistry
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• v.43 no.2
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• pp.48-55
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• 2021

Purpose: This study aimed to analyze deformation according to post-curing of complete arch artificial teeth for temporary dentures printed with a digital light processing (DLP) printer. Methods: An edentulous model was prepared and an occlusal rim was produced. The edentulous model and occlusal rim were scanned using a model scanner. A complete denture was designed using a dental computer-aided design, and the denture base and artificial tooth were separated. Ten complete arch artificial teeth were printed using a 3D printer (DLP). Complete arch artificial teeth was classified into the following three groups: a group no post-curing (NC), a group with 10 minutes post-curing (10M), and a group with 20 minutes post-curing (20M). Specimens were scanned using a model scanner. The scanned data were overlapped with the reference data. Statistical analysis was performed using one-way ANOVA analysis of variance, Kruskal-Wallis test, and Mann-Whitney U test (α=0.05). Results: Regarding the overall deviation of complete arch artificial teeth, the NC group showed the lowest mean deviation of 111.13 ㎛ and the 20M group showed the highest mean deviation of 131.03 ㎛. There were statistically significant differences among the three groups (p<0.05). Conclusion: The complete arch artificial tooth showed deformation due to post-curing. In addition, the largest shrinkage deformation was observed at 10 minutes of post-curing, whereas the least deformation was observed at 20 minutes.