• KIPS Transactions on Software and Data Engineering
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• v.9 no.1
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• pp.11-16
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• 2020

3D printing is one of the emerging technologies and getting a lot of attention. To do 3D printing, 3D model is first generated, and then converted to G-code which is 3D printer's operations. Facet, which is a small triangle, represents a small surface of 3D model. Depending on the height or precision of the 3D model, the number of facets becomes very large and so the conversion time from 3D model to G-code takes longer. Apach Hadoop is a software framework to support distributed processing for large data set and its application range gets widening. In this paper, Hadoop is used to do the conversion works time-efficient way. 2-phase distributed algorithm is developed first. In the algorithm, all facets are sorted according to its lowest Z-value, divided into N parts, and converted on several nodes independently. The algorithm is implemented in four steps; preprocessing - Map - Shuffling - Reduce of Hadoop. Finally, to show the performance evaluation, Hadoop systems are set up and converts testing 3D model while changing the height or precision.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.16 no.3
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• pp.1-8
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• 2017

Tool path generation is a part of process planning in 3D printing. This is done before actual printing by a computer rather than an AM machine. The mesh geometry of the 3D model is sliced layer-by-layer along the Z-axis and tool paths are generated from the sliced layers. Each 2-dimensional layer can have two types of printing paths: (i) shell and (ii) infill. Shell paths are made of offset loops. During shell generation, twists can be produced in offset loops which will cause twisted tool paths. As a twisted tool path cannot be printed, it is necessary to remove these twists during process planning. In this research, An algorithm is presented to remove twists from the offset loops. To do so the path segments are traversed to identify twisted points. Outer offset loops are represented in the counter-clockwise segment order and clockwise rotation for the inner offset loop to decide which twisted loop should be removed. After testing practical 3D models, the proposed algorithm is verified to use in tool path generation for 3D printing.

• Journal of Engineering Education Research
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• v.24 no.3
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• pp.42-49
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• 2021

This paper deals with the development and application of a 3D printing education program implemented to cultivate creative fusion-type talents required by the 4th Industrial Revolution. Specifically, the entire process developed by applying the ADDIE program development model, from 3D modeling to post-processing of printed materials, was performed individually and for each team for about 200 second-year college students for two weeks. Through this program, students develop the basic ability to apply 3D printing to the learning curriculum, the ability to solve problems through cooperative interactions between team members, and convergence thinking ability by collaborating within the team by students from various major fields. They are proved by analyzing an education satisfaction survey conducted after application of the program. In conclusion, the program of this paper presents a methodology for effective 3D printing education in universities.

• Journal of radiological science and technology
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• v.41 no.1
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• pp.61-66
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• 2018

The recent 3D printing technology is used in various medical, manufacturing, and education fields and is more efficient in terms of production process, time, and cost than existing production. Especially in fracture surgery, interest and research have been focused on improving accuracy, shortening of operation time and recovery time, and reducing reoperation. However, because of the financial and technical problems of the 3D printer and the file conversion program, the 3D printing is made directly at the hospital, and it is not generally used for diagnosis of fracture and surgical research. In this study, to solve those problems, clavicle CT imaging was switched into Osirix Open Source DICOM Viewer, Stereolithography file conversion programs and commercial Terarecon 3D DICOM Viewer, file conversion programs, and then clavicle fracture model was directly made through 3D printer of fused filament fabrication wire additive processing method, and then the accuracy of the shape was compared and analyzed. Clavicle fracture models printed in two methods were blind-tested on clinicians of general hospitals' orthopedics and radiologic technicians with over 10 years of experiences, and then their analysis opinions of resolution reviews were analyzed. The result showed no difference. The 3D printing model with open source DICOM STL file conversion program used was applicable to clinical, so it is considered useful in precision diagnosis of fracture and operation plans.

• Journal of International Society for Simulation Surgery
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• v.3 no.1
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• pp.36-38
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• 2016

Fibrous dysplasia is a relatively rare disease but the management would be quite challenging. Because this is not a malignant tumor, the preservation of the facial contour and the various functions seems to be important in treatment planning. Until now the facial bone reconstruction with autogenous bone would be the standard. Although the autogenous bone would be the ideal one for facial bone 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, facial bone 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 maxillary anatomy as possible using the 3D printing model, 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 molded Titanium mesh to reconstruct three-dimensional maxillary structure during the operation. This prefabricated Titanium-mesh implant was then inserted onto the defected maxilla and fixed. Three dimensional printing technique of titanium material based on the computer simulation turned out to be successful in this patient. Individualized approach for each patient could be an ideal way to restore the facial bone.

• Journal of Powder Materials
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• v.31 no.2
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• pp.119-125
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• 2024

The n-type Bi_2-xSb_xTe₃ compounds have been of great interest due to its potential to achieve a high thermoelectric performance, comparable to that of p-type Bi_2-xSb_xTe₃. However, a comprehensive understanding on the thermoelectric properties remains lacking. Here, we investigate the thermoelectric transport properties and band characteristics of n-type Bi_2-xSb_xTe₃ (x = 0.1 - 1.1) based on experimental and theoretical considerations. We find that the higher power factor at lower Sb content results from the optimized balance between the density of state effective mass and nondegenerate mobility. Additionally, a higher carrier concentration at lower x suppresses bipolar conduction, thereby reducing thermal conductivity at elevated temperatures. Consequently, the highest zT of ~ 0.5 is observed at 450 K for x = 0.1 and, according to the single parabolic band model, it could be further improved by ~70 % through carrier concentration tuning.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.9
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• pp.787-792
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• 2015

Recently, 3D printing technology is a hot issue in various industrial fields. According to the user's application, it allows for the free form fabrication method to be utilized in a wide range. The powder based fusion technique is one of the 3D printing methods. When using this method it is possible to apply the various binder jetting techniques such as piezo, thermal bubble jet, dispenser and so on. In this paper, a multi thermal bubble ink jet was integrated for jetting of powder binding material and developing a power fused 3D printing system. For high quality 3D printing parts, it needs an analysis and evaluation of the behavior of the thermal bubble ink jet head. In the experiment, a correlation between jetting binder quantity and layer thickness of powder was investigated, and a 3D part model was fabricated, which was used by measuring the scale factor.

• Journal of radiological science and technology
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• v.40 no.3
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• pp.433-441
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• 2017

The 3D printing selective laser sintering (SLS) and stereo lithography apparatus (SLA) method used for bone model production has good precision and resolution, but the printers are expensive and need professional knowledge for operation. The program that converts computed tomography digital imaging and communications in medicine (DICOM) file into STL (stereolithography) file is also expensive so requesting 3D printing companies takes a lot of time and cost, which is why they are not generally utilized in surgery. To produce bone models of fractured patients, the use of 3D imaging conversion program and 3D printing system should be convenient, and the cost of device and operation should be low. Besides, they should be able to produce big size bone models for application to surgery. Therefore, by using an fused deposition modeling (FDM) method 3D printer that uses thermoplastic materials such as DICOM Viewer OsiriX and plastic wires, this study developed 3D printing system for Fracture surgery Patients customized bone model production for many clinics to use for surgery of fracture patients by universalizing with no limit in printing sizes and low maintenance and production cost. It is expected to be widely applied to the overall areas of orthopedics' education, research and clinic. It is also expected to be conveniently used in not only university hospitals but also regular general hospitals.

• Journal of The Korean Association of Information Education
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• v.19 no.2
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• pp.167-174
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• 2015

A recent increase of interests on the influence of 3D printing and low prices of 3D printers makes a high possibility of 3D printer adoption as a educational equipment in public education settings. The Ministry of Science, ICT and Future Planning and Ministry of Trade, Industry and Energy proposed '3D printing industry development strategies', and had pilot schools to include understanding of 3D printing concepts and practices in the primary, secondary and high schools' curriculum. However, even if 3D printers were provided in educational settings, the research on educational content and methods to properly react to this change is very limited. Therefore, this study reviewed various 3D modeling software because a modeling skill is a prerequisite skill to use 3D printers, and proposed a creative design spiral based teaching content that can be incorporated in elementary school contexts.

• Journal of Microbiology and Biotechnology
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• v.32 no.12
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• pp.1573-1582
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• 2022

In this study, we investigated the optimal conditions for 3D structure printing of alternative fats that have the textural properties of lard using beeswax (BW)-based oleogel by a statistical analysis. Products printed with over 15% BW oleogel at 50% and 75% infill level (IL) showed high printing accuracy with the lowest dimensional printing deviation for the designed model. The hardness, cohesion, and adhesion of printed samples were influenced by BW concentration and infill level. For multi-response optimization, fixed target values (hardness, adhesiveness, and cohesiveness) were applied with lard printed at 75% IL. The preparation parameters obtained as a result of multiple reaction prediction were 58.9% IL and 16.0% BW, and printing with this oleogel achieved fixed target values similar to those of lard. In conclusion, our study shows that 3D printing based on the BW oleogel system produces complex internal structures that allow adjustment of the textural properties of the printed samples, and BW oleogels could potentially serve as an excellent replacement for fat.