• Journal of radiological science and technology
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• v.42 no.6
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• pp.447-454
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• 2019

In order to improve and supplement the shielding method for electron beam treatment, we designed a patient-specific shielding method using a 3D printer, and evaluated the usefulness by comparing and analyzing the distribution of electron beam doses to adjacent organs. In order to treat 5 cm sized superficial tumors around the lens, a CT Simulator was used to scan the Alderson Rando phantom and the DICOM file was converted into an STL file. The converted STL file was used to design a patient-specific shield and mold that matched the body surface contour of the treatment site. The thickness of the shield was 1 cm and 1.5 cm, and the mold was printed using a 3D printer, and the patient customized shielding block (PCSB) was fabricated with a cerrobend alloy with a thickness of 1 cm and 1.5 cm. The dosimetry was performed by attaching an EBT3 film on the surface of the Alderson Rando phantom eyelid and measuring the dose of 6, 9, and 12 MeV electron beams on the film using four shielding methods. Shielding rates were 83.89%, 87.14%, 87.39% at 6, 9, and 12 MeV without shielding, 1 cm (92.04%, 87.48%, 86.49%), 1.5 cm (91.13%, 91.88% with PSCB), 92.66%) The shielding rate was measured as 1 cm (90.7%, 92.23%, 88.08%) and 1.5 cm (88.31%, 90.66%, 91.81%) when the shielding block and the patient-specific shield were used together. PCSB fabrication improves shielding efficiency over conventional shielding methods. Therefore, PSCB may be useful for clinical application.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.6
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• pp.193-198
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• 2021

In this study, the rheological characteristics and of 3D printing composite materials and the compressive strength characteristics according to the lamination patterns were evaluated. As a result of rheology test, rapid material change was observed after 60 minutes of extrusion, yielding stress 1.4 times higher than immediately after mixing, and plastic viscosity was 14.94-25.62% lower. The compressive strength of the specimens manufactured in the mold and the laminated specimens were compared, and the lamination pattern of the laminated specimens were 0°, 45°, and 90° as variables. The compressive strength of the mold casting specimen and the laminated specimen from 1 to 28 days of age showed similar performance regardless of the lamination pattern. In particular, at the age of 28 days, the modulus of elasticity, maximum compressive strength, and strain at maximum stress of all specimens were almost the same. In order to analyze the interface of the laminated specimens, X-ray CT analysis of the specimen whose compressive strength were measured was performed. Through CT analysis, it was confirmed that cracks did not occur at the lamination interface, which can be judged that the interface in the laminated specimen behaved in an integrated manner.

• Design & Manufacturing
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• v.14 no.1
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• pp.49-55
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• 2020

In this study, the fatigue behavior and fatigue life characteristics of PA2200 specimens fabricated by SLS 3D printer were studied. Fatigue tests were performed according to the standard specification (ASTM E468) and fatigue life curves were obtained. In order to perform the fatigue test, mechanical properties were measured according to the test speed of the simple tensile test, and the self-heating temperature of the specimen according to the test speed was measured using an infrared temperature measuring camera in consideration of heat generation due to plastic deformation. There was no significant difference within the set test speed range and the average self-heating temperature was measured at 38.5 ℃. The mechanical strength at the measured temperature showed a relatively small difference from the mechanical strength at room temperature. Fatigue test conditions were established through the preceding experiments, and the loading conditions below the tensile strength at room temperature 23 ℃ were set as the cyclic load. The maximum number of replicates was less than 100,000 cycles, and the fracture behavior of the specimens with the repeated loads showed the characteristics of Racheting. It was confirmed that SLS 3D printing PA2200 material could be applied to the Basquin's S-N diagram for the fatigue life curve of metal materials. SEM images of the fracture surface was obtained to analyze the relationship between the characteristics of the fracture surface and the number of repetitions until failure. Brittle fracture, crazing fracture, grain melting, and porous fracture surface were observed. It was shown that the larger the area of crazing damage, the longer the number of repetitions until fracture.

• Journal of Investigative Cosmetology
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• v.15 no.1
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• pp.49-58
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• 2019

Special makeup companies are able to overcome the difficulties resulting from increase in labor costs by enhancing work efficiency through fabrication of prosthesis using 3D printing. With accurate fabrication being enabled, a given business area can be broadened to tailor-made prosthesis such as anaplastology. In this regard, the current study attempted to investigate the possibility of digital processing through special makeup molds and silicon patches designed using a FDM 3D printer, and the results are as follows: First, when a design modeled through the 3D graphics software 'ZBrush' was printed using a FDM 3D printer, the exact shape and surface texture which were observed on the computer monitor could be exactly obtained. Second, negative molds fabricated with flexible TPU filament were easier to use and displayed a more complete silicon mold than PLA filament-based negative molds. Third, the support, which is a disadvantage of the 3D printer, it was able to align objects or split the molds in such a way so that no support was formed in the slicing program. Fourth, the shrinkage rate of the outputs acquired through PLA or TPU filament did not change the shape of the silicon molds. Fifth, the texture of the fine contours which was found in silicon molds varied depending upon the object alignment angle in the slicing program. They can also be viewed differently depending upon the angle of lighting. To use a 3D printer in the fabrication of special makeup molds, therefore, it is necessary to examine how to fabricate them easily by concealing contours as much possible. It is also necessary to analyze the images acquired after attaching the colored silicon patches and check their availability.

• The Journal of Advanced Prosthodontics
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• v.13 no.6
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• pp.361-372
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• 2021

PURPOSE. To improve the clinical effects of complete denture use and simplify its clinical application, a digital complete denture restoration workflow (Functional Suitable Digital Complete Denture System, FSD) was proposed and preliminary clinical evaluation was done. MATERIALS AND METHODS. Forty edentulous patients were enrolled, of which half were treated by a prosthodontic chief physician, and the others were treated by a postgraduate student. Based on the primary impression and jaw relation obtained at the first visit, diagnostic denture was designed and printed to create a definitive impression, jaw relation, and esthetic confirmation at the second visit. A redesigned complete denture was printed as a mold to fabricate final denture that was delivered at the third visit. To evaluate accuracy of impression made by diagnostic denture, the final denture was used as a tray to make impression, and 3D comparison was used to analyze their difference. To evaluate the clinical effect of FSD, visual analogue scores (VAS) were determined by both dentists and patients. RESULTS. Two visits were reduced before denture delivery. The RMS values of 3D comparison between the impression made via diagnostic dentures and the final dentures were 0.165 ± 0.033 mm in the upper jaw and 0.139 ± 0.031 mm in the lower jaw. VAS ratings were between 8.5 and 9.6 in the chief physician group, while 7.7 and 9.5 in the student group; there was no statistical difference between the two groups. CONCLUSION. FSD can simplify the complete denture restoration process and reduce the number of visits. The accuracy of impressions made by diagnostic dentures was acceptable in clinic. The VASs of both dentists and patients were satisfied.

• Journal of Radiation Protection and Research
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• v.47 no.3
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• pp.152-157
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• 2022

Background: The hemi-body electron beam irradiation (HBIe^-) technique has been proposed for the treatment of mycosis fungoides. It spares healthy skin using an electron shield. However, shielding electrons is complicated owing to electron scattering effects. In this study, we developed a thimble-like head bolus shield that surrounds the patient's entire head to prevent irradiation of the head during HBIe^-. Materials and Methods: The feasibility of a thimble-like head bolus shield was evaluated using a simplified Geant4 Monte Carlo (MC) simulation. Subsequently, the head bolus was manufactured using a three-dimensional (3D) printed mold and Ecoflex 00-30 silicone. The fabricated head bolus was experimentally validated by measuring the dose to the Rando phantom using a metal-oxide-semiconductor field-effect transistor (MOSFET) detector with clinical configuration of HBIe^-. Results and Discussion: The thimble-like head bolus reduced the electron fluence by 2% compared with that without a shield in the MC simulations. In addition, an improvement in fluence degradation outside the head shield was observed. In the experimental validation using the inhouse-developed bolus shield, this head bolus reduced the electron dose to approximately 2.5% of the prescribed dose. Conclusion: A thimble-like head bolus shield for the HBIe^- technique was developed and validated in this study. This bolus effectively spares healthy skin without underdosage in the region of the target skin in HBIe^-.