• Journal of Advanced Navigation Technology
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• v.13 no.6
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• pp.984-990
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• 2009

Halftoning is very important image processing techniques in the digital printing industry which is a process of converting a continuous-tone image to bi-level tone image. In this paper we introduce a new digital halftoning method based on maze generation algorithm as a replacement algorithm of halftoning with space-filling curve. Previous error-diffusion methods based on space-filling curve suffer from regular pattern artifacts from uniform scan pattern. We use maze generation algorithm to remove this undesirable pattern of space-filling curve method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.6
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• pp.849-852
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• 2021

This paper presents a vision based tire mold inspection system where mold defects are inspected and the sizes of specific parts of the mold are measured. There are a lot of challenging issues as letters and pictures of intaglio are engraved on a bright surface of the tire mold. To solve the issues, we carefully selected a line-scan camera and a line light. In addition, we used PLC to control the mechanical parts. The developed system provides inspection of misspelled and deformed letters as well as a variety of the functions such as size measurement of engraved regions and inspection report file creation.

• Journal of KIISE
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• v.43 no.5
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• pp.516-523
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• 2016

For old-age makeups, makeup artists first make a mold cast of an actor's face using plaster and then sculpt wrinkles in clay on the plaster mold. After finishing the clay sculpture, its negative plaster mold is fabricated and silicone skin patches are finally made for application to the actor's face. This process takes a few days and is tedious for actors and makeup artists. With recent advances in 3D printing and scanning technology, it is becoming easier to scan and fabricate 3D faces. This paper presents a new pipeline composed of facial scanning, interactive wrinkle modeling, and mold printing stages to easily and efficiently fabricate silicone masks for old-age makeups without the use of plaster and clay. An intuitive sketch interface based on a normal map is proposed for the creation of wrinkles in real time, even with a high-resolution face model. Then the geometry of the final wrinkles is reconstructed using a depth map and the negative mold of the wrinkled face is printed. We also show that the presented pipeline can fabricate a silicone mask more conveniently than the traditional one that consists of pouring silicone into the prepared negative mold and then overlapping the mold with the original positive one.

• The Journal of the Korea Contents Association
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• v.16 no.2
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• pp.186-199
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• 2016

The shoe last which is the framework for the shoemaking is intensively combined with the 3D data and technologies. International shoe companies have already commercialized 3D printing technology in producing the shoe, but domestic shoe companies are still in their early stages. This study used the 3D scanning, 3D modeling and 3D printing of the high-technology to make the shoe last. This 3D producing processes should be helpful in building competitiveness in domestic shoe industry. The 3D foot scanning data of men in 30s(n=200) were collected in SizeKorea(2010). The basic statistics, factor and cluster analysis were performed. They were categorized in 3 groups by 3D foot measurement data, and the standard models were selected in each group. The cross sections in XY, YZ and XZ planes sliced from 3D scan data of the standard model were used in the sketches of the 3D shoe last modeling. The 3D shoe last was modeled by Solidworks CAD and printed by MakerBot Replicator2; a desktop 3D printer. This research showed the potential for utilization of 3D printing technology in the domestic shoe industry. The 3D producing process; 3D scanning, 3D modeling and 3D printing is expected to utilized widely in the fashion industry within the nearest future.

• The Journal of Korean Academy of Prosthodontics
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• v.60 no.2
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• pp.202-210
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• 2022

Recently with the advance in digital dentistry, the fabrication of dentures using computer-aided design and computer-aided manufacturing (CAD-CAM) is on the rise. The denture designed through a CAD software can be produced in a 3-dimensional manufacturing process. This process includes a subtractive processing method such as milling and an additive processing method such as 3D printing and in which it can be applied efficiently in more complex structures. In this case, complete dentures were fabricated using Stereolithography (SLA)-based 3D printing to shorten the production time and interval of visits in patient with physical disabilities due to cerebral infarction. For definitive impression, the existing interim denture was digitally replicated and used as an individual tray. The definitive impression obtained with polyvinyl siloxane impression material was including information about the inclination and length of the maxillary anterior teeth, vertical dimension, and centric relation. In addition, facial scan data with interim denture was obtained so that it can be used as a reference in determination of the occlusal plane and in arrangement of artificial teeth during laboratory work. Artificial teeth were arranged through a CAD program, and a gingival festooning was performed. The definitive dentures were printed by SLA-based 3D printer using a FDA-approved liquid photocurable resin. The denture showed adequate retention, support, and stability, and results were satisfied functionally and aesthetically.

• Progress in Medical Physics
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• v.32 no.4
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• pp.99-106
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• 2021

Purpose: In this study, we aimed to manufacture a patient-specific gel phantom combining three-dimensional (3D) printing and polymer gel and evaluate the radiation dose and dose profile using gel dosimetry. Methods: The patient-specific head phantom was manufactured based on the patient's computed tomography (CT) scan data to create an anatomically replicated phantom; this was then produced using a ColorJet 3D printer. A 3D polymer gel dosimeter called RTgel-100 is contained inside the 3D printing head phantom, and irradiation was performed using a 6 MV LINAC (Varian Clinac) X-ray beam, a linear accelerator for treatment. The irradiated phantom was scanned using magnetic resonance imaging (Siemens) with a magnetic field of 3 Tesla (3T) of the Korea Institute of Nuclear Medicine, and then compared the irradiated head phantom with the dose calculated by the patient's treatment planning system (TPS). Results: The comparison between the Hounsfield unit (HU) values of the CT image of the patient and those of the phantom revealed that they were almost similar. The electron density value of the patient's bone and brain was 996±167 HU and 58±15 HU, respectively, and that of the head phantom bone and brain material was 986±25 HU and 45±17 HU, respectively. The comparison of the data of TPS and 3D gel revealed that the difference in gamma index was 2%/2 mm and the passing rate was within 95%. Conclusions: 3D printing allows us to manufacture variable density phantoms for patient-specific dosimetric quality assurance (DQA), develop a customized body phantom of the patient in the future, and perform a patient-specific dosimetry with film, ion chamber, gel, and so on.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.10
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• pp.346-351
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• 2018

Metal three-dimensional (3D) printing technologies are mainly classified as powder bed fusion (PBF) and direct energy deposition (DED) methods according to the method of application of a laser beam to metallic powder. The DED method can be used to fabricate fine and hard 3D metallic structures by applying a strong laser beam to a thin layer of metallic powder. The PBF method involves slicing 3D graphics to be a certain height, laminating metal powders, and making a 3D structure using a laser. While the DED method has advantages such as laser cladding and metallic welding, it causes problems with low density when 3D shapes are created. The PBF method was introduced to address the structural density issues in the DED method and makes it easier to produce relatively dense 3D structures. In this paper, thin lines were produced by using PBF 3D printers with stainless-steel powder of roughly $30{\mu}m$ in diameter with a galvano scanner and fiber-transferred Nd:YAG laser beam. Experiments were carried out to find the optimal conditions for the width of a line depending on the processing times, laser power, spot size, and scan speed. The optimal conditions were two scanning processes in one line structure with a laser power of 30 W, spot size of $28.7{\mu}m$, and scan speed of 200 mm/s. With these conditions, a minimum width of about $85.3{\mu}m$ was obtained.

• Clean Technology
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• v.19 no.4
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• pp.410-415
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• 2013

The supercapacitors were fabricated using silver (Ag) nano paste and activated carbon paste on the polyimide (PI) film and 5% potassium polyacrylate (PAAK) was used for gel electrolyte. In this paper, the current collector film and the electrode film were fabricated using screen printing. The thickness of printed silver paste was $7.3{\mu}m$ and the sheet resistance has the range of $5-7m{\Omega}/square$. An activated carbon with a surface area of $1,968m^2/g$, an electronic conducting agent (SUPER P, TIMCAL) and poly (4-vinylphenol) were mixed in 2-(2-buthoxyethoxy) ethyl acetate (BCA) with a ratio of 7:1:3 to fabricate the electrode paste. To analyze electrochemical characteristics, cyclic voltammetry was performed to evaluate the stability of the devices under the voltage range of -0.5-0.5 V. The calculated specific capacitances were 44.04 and 8.62 F/g for 10 and 500 mV/s scan rates, respectively.

• Journal of Technologic Dentistry
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• v.45 no.1
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• pp.1-7
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• 2023

Purpose: To evaluate the marginal and internal fit of metal coping fabricated by a metal three-dimensional (3D) printer that uses selective laser melting (SLM). Methods: An extraoral scanner was used to scan a die of the prepared maxillary right first molar, and the coping was designed using computer-aided design software and saved as an stereo lithography (STL) file. Ten specimens were printed with an SLM-type metal 3D printer (SLM group), and 10 more specimens were fabricated by casting the castable patterns output generated by a digital light processing-type resin 3D printer (casting the 3D printed resin patterns [CRP] group). The fit was measured using the silicon replica technique, and 8 points (A to H) were set per specimen to measure the marginal (points A, H) and internal (points B~G) gaps. The differences among the groups were compared using the Mann-Whitney U-test (α=0.05). Results: The mean of marginal fit in the SLM group was 69.67±18.04 ㎛, while in the CRP group was 117.10±41.95 ㎛. The internal fit of the SLM group was 95.18±41.20 ㎛, and that of the CRP group was 86.35±32 ㎛. As a result of statistical analysis, there was a significant difference in marginal fit between the SLM and CRP groups (p<0.05); however, there was no significant difference in internal fit between the SLM group and the CRP group (p>0.05). Conclusion: The marginal and internal fit of SLM is within the clinically acceptable range, and it seems to be applicable in terms of fit.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.732-737
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• 2005

Distal 3D Real Object Duplication System(RODS) consists of 3D Scanner and Solid Freeform Fabrication System(SFFS). It is a device to make three-dimensional objects directly from the drawing or the scanning data. In this research, we developed an office type SFFS based on Three Dimensional Printing Process and a industrial SFFS using Dual Laser. An office type SFFS applied sliding mode control with sliding perturbation observer(SMCSPO) algorithm for control of this system. And we measured process variables about droplet diameter measurement and powder bed formation etc. through experiments. Also, in order to develop more elaborate and speedy system for large objects than existing SLS process, this study applies a new Selective Multi-Laser Sintering(SMLS) process and 3-axis dynamic Focusing Scanner for scanning large area instead of the existing $f\theta$ lens. In this process, the temperature has a great influence on sintering of the polymer. Also the laser parameters are considered like that laser beam power, scan speed, scan spacing. Now, this study is in progress to eveluate the effect of experimental parameters on the sintering process.