• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.24-31
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• 2024

Mortar has been applied in most previous studies on 3D concrete printing. In such cases, however, the economic efficient cannot help decreasing due to higher binder contents and larger amount of fine aggregates. In order to enhance the applicability of 3D printing technology to construction industry, therefore, 3D concrete printing technology utilizing coarse aggregates needs to be developed further. This study aims at proposing the mix design process of concrete containing coarse aggregates for 3D printing. Based on extensive literature review and experimental studies, the mix proportion suitable for 3D printing has been derived, and the extrudability of concrete with coarse aggregates has been verified through 3D printing tests. The primary variable of the extrudability tests was the contents of viscosity modifying agent (VMA), and the extrudability was quantitatively evaluated by measuring dimensions, distribution of aggregates, and surface quality of 3D-printed filaments. The test results showed that the dimensional suitability and surface quality were improved as the VMA contents were larger, and the coarse aggregates were evenly distributed in the section of filament regardless of the VMA contents. Based on the test results, the mix design process for concrete containing coarse aggregates for 3D printing has been proposed.

• Elastomers and Composites
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• v.51 no.4
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• pp.301-307
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• 2016

Additive manufacturing (AM), so called 3D Printing is a new manufacturing process and is getting attraction from many industries. There are several methods of 3D printing. Among them fused deposition modeling (FDM) type is most widely used by reason of cheap maintenance, easy operation and variety of polymeric materials. Articles manufactured by 3D printing have weak deposition strength compared with conventionally manufactured products. Deposition strength of FDM type 3D printed article is highly dependent of deposition temperature. Subsequently the nozzle temperature in the FDM type 3D printing is very important and it is controlled by heat source in the 3D printer. Nozzle is connected with heat block and barrel, and heat block contains heat source. Nozzle becomes hot through heat conduction from heat source. Nozzle temperature has been predicted for various thermal boundary conditions by computer simulation and compared with experimental measurement. Nozzle temperature highly depends upon thermal conductivities of heat block and nozzle. Simulation results are good agreement with experiment.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.4
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• pp.1-8
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• 2017

This paper concerns the possibility of 3D printing reverse idle gears for tractor transmission. For the purposes of this experiment, idle gears were manufactured using a SLA 3D printer, FDM 3D printer, and through machining. The accuracy of the idle gears produced in these three different ways were evaluated by the properties of their outer diameter, inner diameter, roundness, concentricity, parallelism, span, backlash, and gear grade. The tooth characteristics of the idle gears were evaluated by their profile, lead, and the pitch of the gears. The results of this experiment determined that the surface conditions created by the finishing process had a significant impact on the dimensional accuracy of the gears and the characteristics of their teeth.

• Journal of Biomedical Engineering Research
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• v.41 no.2
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• pp.75-83
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• 2020

In large-scale hospitals, the department of biomedical engineering should always provide quick repair service for damaged medical devices to guarantee continuous patient treatment. However, in actual circumstances, there are so many time-consuming issues that delays device repair for weeks or even months; therefore, it is required to prepare alternative ways for quick repair service. In this study, we first mentioned about the regulation issues in Korea about the 3D printing-based medical device repair, and then introduced the results of our preliminary study that evaluated the feasibility of 3D printing-based medical device repair before real-field application. Results of the study demonstrated that, in all of the 23 cases, parts for repair that were manufactured by 3D-printing were successfully fixed and connected to the main body of the original device, and showed sufficient rigidity for protecting internal parts of the device. Considering the experimental results, medical device repair by applying 3D printing technology can be a promising alternative in cases when regular repair process is not available or takes too much time.

• Elastomers and Composites
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• v.55 no.1
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• pp.46-50
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• 2020

Material extrusion (ME)-type 3D printing is the most popular among the 3D printing processes. In this study, the cross-section morphologies of ME-type 3D printing manufactured specimens were observed with respect to the thermal properties of the material. The cross-section morphology of a specimen is related to the deposition strength, and the outside profile of the cross-section is related to the surface roughness. The filaments used in this study, with different thermal conductivities, were the acrylonitrile-butadiene-styrene (ABS), the high impact polystyrene (HIPS), the glycol-modified polyethylene terephthalate (PETG), and the polylactic acid (PLA). The cross-sections and the surfaces of the 3D manufactured specimens were examined. In ME-type 3D printing, the filaments are extruded through a nozzle and they form a layer. These layers rapidly solidify and as a result, they become a product. The thermal conductivity of the material influences the cooling and solidification of the layers, and subsequently the cross-section morphology and the surface roughness.

• Journal of the Korean Society of Mineral and Energy Resources Engineers
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• v.56 no.3
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• pp.260-269
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• 2019

The application of 3D printing technology in seismic physical modeling was investigated and the related domestic research was conducted. First, seven types of additive manufacturing methods were evaluated. In this report, to confirm the application of 3D printing technology, related studies in domestic and international journals of geophysics were searched and a comprehensive analysis was conducted according to year and the additive manufacturing type. The analysis showed that studies on 3D printing technology have been dominantly conducted since the 2010s, which corresponds to the time when 3D printers were commercialized. Moreover, 87% of the studies used the material extrusion additive manufacturing method, and the research was conducted in specific universities. This research can be used as basic data for application of 3D printing technology in geophysics.

• The Journal of Advanced Prosthodontics
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• v.10 no.3
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• pp.245-251
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• 2018

PURPOSE. To evaluate the accuracy of a model made using the computer-aided design/computer-aided manufacture (CAD/CAM) milling method and 3D printing method and to confirm its applicability as a work model for dental prosthesis production. MATERIALS AND METHODS. First, a natural tooth model (ANA-4, Frasaco, Germany) was scanned using an oral scanner. The obtained scan data were then used as a CAD reference model (CRM), to produce a total of 10 models each, either using the milling method or the 3D printing method. The 20 models were then scanned using a desktop scanner and the CAD test model was formed. The accuracy of the two groups was compared using dedicated software to calculate the root mean square (RMS) value after superimposing CRM and CAD test model (CTM). RESULTS. The RMS value ($152{\pm}52{\mu}m$) of the model manufactured by the milling method was significantly higher than the RMS value ($52{\pm}9{\mu}m$) of the model produced by the 3D printing method. CONCLUSION. The accuracy of the 3D printing method is superior to that of the milling method, but at present, both methods are limited in their application as a work model for prosthesis manufacture.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.5
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• pp.143-148
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• 2018

3D printing has been expanding beyond the bio/nano field to the automobile and aviation industries. 3D-printing technology has to overcome real problems to have economic value compared to its unlimited usability. Typically, the difference in mechanical strength along the lamination direction requires sufficient research to ensure reliability. In this paper, we study the anisotropic properties of ABS based on the stacking method of FDM 3D printing. Specifically, the mechanical properties of ABS material are determined through a tensile test and 3-point bending test, and the in-plane orthotropic properties are ascertained.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.909-917
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• 2018

3D printing technology is expected to be an innovative technology of the manufacturing industry during the 4th industrial revolution, and it is being used in various fields including biotechnology and medical field. In this study, we verified the printing materials through Monte Carlo simulation to evaluate the radiation shielding ability of the raw material using this 3D printing technology. In this paper, the printing materials were selected from the raw materials available in a general-purpose FDM-based 3D printer. Simulation of the ICRU phantom and the shielding system was carried out to evaluate the shielding effect by evaluating the particle fluence according to the type and energy of radiation. As a result, the shielding effect tended to decrease gradually with increasing energy in the case of photon beam, and the shielding effect of TPU, PLA, PVA, Nylon and ABS gradually decreased in order of materials. In the case of the neutron beam, the neutron intensity increases at a low thickness of 5 ~ 10 mm. However, the effective shielding effect is shown above a certain thickness. The shielding effect of printing material is gradually increased in the order of Nylon, PVA, ABS, PLA and TPU Respectively.

• Journal of the Korean Society of Clothing and Textiles
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• v.45 no.1
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• pp.155-167
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• 2021

The latest innovation in the field of fashion comes in the form of 3D-printed clothing. This study explores the composition and characteristics of the shapes in the architecture of Zaha Hadid, a representative architectural designer who expresses space in three dimensions. Hadid applies his aesthetic to fashion design using these distinctive geometric shapes to create design motifs as well as develop new clothing material with 3D printing technology. The research was conducted as follows. First, the lines and arrangement of the geometric shapes in Zaha Hadid's architecture were analyzed so that his design principles could be used as a theoretical basis for this study. The study also reviewed geometric fashion designs using 3D printing technology over the last ten years. Second, we developed triangular modules with rods and tongs that could be fashioned into clothing using fused deposition modeling (FDM) 3D printers. Lastly, the 3D printing fashion design was developed to explore new silhouettes, textures, and a novel way of producing clothing. This study hopes to serve as a stepping-stone for further research on innovations that combine fashion with technology.