• 한국기계가공학회지
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• 제16권4호
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• pp.9-15
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• 2017

In hot forming process, the dies in which excessive worn or crack occurs is reused after repair. Generally hot forming dies are recycled through a welding repair method. Welding repair methods are highly dependent on the skills of engineer. It causes process defects such as dimensional defects and structural defects. Recently, the metal 3D printing method has been applied to the repair of used dies. The aim of this study is to evaluate the wear characteristics of AISI H13 tool steel repaired by 3D printing method. Three kinds of wear specimens were fabricated by using 3D printing, welding, and initial material. A pin-on-disk wear test was carried out to evaluate the wear characteristics. From the result of wear test, the wear characteristics of 3D printing method was superior to that of the welded material, and was similar to that of the initial material.

• International Journal of Computer Science & Network Security
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• 제22권7호
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• pp.443-450
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• 2022

The method of studying 3D-technologies abroad and in Ukraine is considered. The analysis of educational resources and experience of use of the equipment in branch is carried out. The didactic principles of the educational process for 3D-printing specialists are determined. The use of FDM technology and the ability to minimize the occurrence of defects in the future have been studied. An analysis of the international experience of the educational process of relevant specialists in the field. The content of training for 3D printing specialists has been developed. The experience of using 3D-technologies is described and the list of recommendations for elimination of defects during production of products by means of additive technologies is made. The recommendations will be useful not only for beginners, but also for experienced professionals in additive technologies. The need to study such experience is the main condition for the development of enterprises in Ukraine that plan to automate their own production. A 3D printing engineer must know the basics of economics and marketing, because his responsibilities include optimizing workflows to reduce the cost and speed up printing. Therefore, the knowledge gained from practical experience presented and in building for learning 3D printing engineers by the authors will be important.

• 한국임상수의학회지
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• 제39권5호
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• pp.246-252
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• 2022

Multilobular osteochondrosarcoma (MLO) reportedly has a good prognosis after complete resection. This study reports the successful treatment of MLO in two dogs using 3-dimensional (3D) printing technology. A nine-year-old castrated male Maltese (Case 1) and a five-year-old castrated male poodle (Case 2) both presented with a mass in the skull. Diagnostic imaging revealed a cranial mass arising from the cranio-orbital and parieto-occipital bones. The masses were resected using 3D-printed osteotomy guides, and the resulting defects were reconstructed using 3D-printed patient-specific implants. Histopathological results confirmed the resection of MLOs with clean margins. Patients routinely recover from surgery without complications. To date, the two patients remain alive without clinical signs of tumor recurrence at 20 and 12 months postoperatively, respectively. In the management of MLO in dogs, 3D printing technology can allow accurate tumor resection, reduced surgical time, and successful reconstruction of large defects.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.125-130
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• 2021

Scaffold is used to produce bio sensor. Scaffold is required high dimensional accuracy. 3D printer is used to manufacture scaffold. 3D printer can't detect defect during printing. Defect detection is very important in scaffold printing. Real-time defect detection is very necessary on industry. In this paper, we proposed the method for real-time scaffold defect detection. Real-time defect detection model is produced using CNN(Convolution Neural Network) algorithm. Performance of the proposed model has been verified through evaluation. Real-time defect detection system are manufactured on hardware. Experiments were conducted to detect scaffold defects in real-time. As result of verification, the defect detection system detected scaffold defect well in real-time.

• 대한두개안면성형외과학회지
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• 제16권1호
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• pp.11-16
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• 2015

Background: Source material used to fill calvarial defects includes autologous bones and synthetic alternatives. While autologous bone is preferable to synthetic material, autologous reconstruction is not always feasible due to defect size, unacceptable donor-site morbidity, and other issues. Today, advanced three-dimensional (3D) printing techniques allow for fabrication of titanium implants customized to the exact need of individual patients with calvarial defects. In this report, we present three cases of calvarial reconstructions using 3D-printed porous titanium implants. Methods: From 2013 through 2014, three calvarial defects were repaired using custom-made 3D porous titanium implants. The defects were due either to traumatic subdural hematoma or to meningioma and were located in parieto-occipital, fronto-temporo-parietal, and parieto-temporal areas. The implants were prepared using individual 3D computed tomography (CT) data, Mimics software, and an electron beam melting machine. For each patient, several designs of the implant were evaluated against 3D-printed skull models. All three cases had a custom-made 3D porous titanium implant laid on the defect and rigid fixation was done with 8 mm screws. Results: The custom-made 3D implants fit each patient's skull defect precisely without any dead space. The operative site healed without any specific complications. Postoperative CTs revealed the implants to be in correct position. Conclusion: An autologous graft is not a feasible option in the reconstruction of large calvarial defects. Ideally, synthetic materials for calvarial reconstruction should be easily applicable, durable, and strong. In these aspects, a 3D titanium implant can be an optimal source material in calvarial reconstruction.

• 실천공학교육논문지
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• 제15권2호
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• pp.419-427
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• 2023

In this study, optimal adhesion conditions to alleviate defects caused by heat shrinkage with FDM type 3D printers with machine learning are researched. Machine learning is one of the "statistical methods of extracting the law from data" and can be classified as supervised learning, unsupervised learning and reinforcement learning. Among them, a function model for adhesion between the bed and the output is presented using supervised learning specialized for optimization, which can be expected to reduce output defects with FDM type 3D printers by deriving conditions for optimum adhesion between the bed and the output. Machine learning codes prepared using Python generate a function model that predicts the effect of operating variables on adhesion using data obtained through adhesion testing. The adhesion prediction data and verification data have been shown to be very consistent, and the potential of this method is explained by conclusions.

• 대한치과보철학회지
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• 제58권4호
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• pp.349-355
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• 2020

외상, 구강암, 선천적 요인 등에 의한 구강 결손시 음식물의 섭취, 흡입성 폐렴 방지, 안모 지지를 위하여 치과용 obturator가 제작된다. 그러나 기존의 전통적인 인상 채득 방법을 이용한 obturator제작 시, 제작 과정에서 술자와 환자, 기공사 모두 번거로운 과정을 거쳐야 하며, 환자는 악안면 보철 치료가 가능한 치과 보철 전문의가 있는 병원을 찾아 방문해야 하는 어려움이 있다. 그러나, 3D printing을 포함한 CAD-CAM 기술을 이용하면 비교적 간단하게 hollow obturator를 제작할 수 있고, 보철 전문의가 없는 지역에서도, 지역 치과의사와 멀리 떨어져 있는 보철 전문의 간의 협진을 통해 수월한 치료가 가능할 수 있다. 본 연구에서는 한국의 상악 구개 결손 환자들의 치료를 위해, 일본에서 obturator를 디자인하고 한국에서 3D printing하여 성공적으로 obturator를 제작하였고, 더불어 원격 치료의 가능성을 확인하였기에 보고하는 바이다.

• 한국분말재료학회지
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• 제30권2호
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• pp.123-129
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• 2023

High-temperature and high-pressure post-processing applied to sintered thermoelectric materials can create nanoscale defects, thereby enhancing their thermoelectric performance. Here, we investigate the effect of hot isostatic pressing (HIP) as a post-processing treatment on the thermoelectric properties of p-type Bi_0.5Sb_1.5Te_3.0 compounds sintered via spark plasma sintering. The sample post-processed via HIP maintains its electronic transport properties despite the reduced microstructural texturing. Moreover, lattice thermal conductivity is significantly reduced owing to activated phonon scattering, which can be attributed to the nanoscale defects created during HIP, resulting in an ~18% increase in peak zT value, which reaches ~1.43 at 100℃. This study validates that HIP enhances the thermoelectric performance by controlling the thermal transport without having any detrimental effects on the electronic transport properties of thermoelectric materials.

• Design & Manufacturing
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• 제13권3호
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• pp.29-34
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• 2019

Cell phone injection is characterized by its small size and thinness. In addition, the product has a short cycle time, requiring a very short production schedule. To produce more accurate products faster, data from experience in producing similar products is required. In this study, two mobile phone models are presented. In this study, the quality problems caused by molding analysis and actual injection molding were analyzed and made into a database. As a result, it was considered that all the defects in the molding analysis do not affect the product in some cases, rather than appear as defects in the actual product. All defects shown in the molding analysis can be made into a database, and based on this data, it will be possible to obtain an effect that can predict more accurately whether it will cause problems after injection.

• 한국분말재료학회지
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• 제26권4호
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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.