• 한국방사선학회논문지
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• 제14권5호
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• pp.627-634
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• 2020

본 연구는 기존의 납을 대신해 친환경 물질인 황산바륨과 3D 프린터 소재인 PLA 필라멘트를 혼합하여 형태학적 구현을 위한 차폐체를 개발하고자 하였다. 환경 물질인 황산바륨 분말 가루와 3D프린터 소재인 PLA 필라멘트를 사용하였으며, 황산바륨 분말 가루와 PLA를 혼합하기 위하여 압출기로 융합 후 3D 프린터로 차폐체를 제작하였다. 황산바륨 파우더 분말 가루와 PLA 필라멘트 혼합비율을 확인하기 위해 혼합입도를 분석하였으며, 혼합된 차폐체의 차폐능을 확인하기 위해 황산바륨 함유량에 따른 두께별 흡수선량을 구하여 선량을 평가한 후 차폐능을 분석했다.황산바륨 분말 입자와 PLA 필라멘트 혼합 입도 평가 시 외관상과 주사전자현미경 관찰사진에서 함유량이 30%일 때 가장 적정비율로 혼합된 것을 확인하였다. 황산바륨 함유량에 따른 두께별 흡수선량 결과에서 함유량이 0%일 때와 각 % 별 함유량을 비교했을 때 두께 0.5 cm에서 흡수선량의 차이가 가장 크게 나타났으며, 바륨함유량이 30%일 때 두께 3 cm에서 가장 낮은 선량값을 나타냈다. 또한 바륨함유량이 30%를 기점으로 함유량이 증가할수록 흡수 선량값은 다시 높아지는 결과가 나타났다. 기존의 납 대신 친환경 물질인 황산바륨을 필라멘트 소재인 PLA와 혼합하여 형태학적인 차폐체를 만들 수 있었다. 혼합물에 대한 바륨의 혼합비율은 30%가 가장 적절하며, 본 연구를 토대로 진단 방사선 분야 내 3D 프린터를 이용한 형태학적 차폐체 구현을 위한 기초 자료로 사용될 것으로 기대한다.

• 한국기계가공학회지
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• 제20권2호
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• pp.38-44
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• 2021

To cater to the transition from single-color to multicolor/multi-material printing, this paper proposes a cartridge-replacing type multi-nozzle Fused Depositon Modeling(FDM) three-dimensional (3D) printer. In the test printing run, tool change failure/wobble/layer shift occurred. It was confirmed that improper support was the cause of this tool change failure. As a solution, spline and electromagnetic cartridges were designed. Wobble was caused by machine vibration and the motor stepping out. To minimize wobble, an additional Z-axis was installed, and the four-point bed leveling method was used instead of the three-point bed leveling method. The occurrence of layer shift was ascribed to the eccentricity of the Z-axis lead screw. Therefore, slit coupler was replaced with an Oldham type. In addition to the mechanical supplementation, the control environment was integrated to prevent accidents and signal errors due to wire connections. Before the final test printing run, a rectifier circuit was added to the motor to secure precise control stability. The final test printing run confirmed that the wobble/layer shift phenomenon was minimized, and the maximum error between layers was reduced to 0.05.

• 한국정밀공학회지
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• 제32권10호
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• pp.917-923
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• 2015

3D Printing has a great advantage for its capabilities in manufacturing complicated structures in a reasonable manufacturing time, and thus is widely used in various fields. Due to the high cost of the equipment and material, a fairly acceptable equipment, the Projection Stereolithography Apparatus (PSLA), has been developed, using the projection pattern approach for the purpose of quick manufacturing. We evaluated its surface quality, as compared with that of other systems. The result is the development of a high-performance, low-cost 3D Printer and its operating software, using LCD and UV LED. Working materials for an optimal manufacturing are suggested in the research, along with some suggestions of basic approaches for enhancing the accuracy and quality of the manufactured structures.

• 한국기계가공학회지
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• 제18권3호
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• pp.33-40
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• 2019

FDM 3D printers have become widespread, and investment in the 3D printer industry is increasing. Therefore, many 3D printers are released and the functions of products are emphasized. However, to lower unit prices, open-type 3D printers are sold in kit form, and their performance is very low. If the 3D printer has many heat sources and is sealed, there is the possibility that the main accessories (the main board, power supply, and motor) will be damaged by trapped heat. At the same time, if the ambient temperature is low due to the properties of the material, the output quality deteriorates. In this study, we analyzed the temperature rise of the main accessories and the quality of the output by the heat bed when a chamber was added to an open-type 3D printer. We also compared the quality of the output due to the air flow with the temperature rise of the main accessories. Moreover, we found the optimal value. As a result of the quality analysis, it was finally confirmed that the case with the chamber at $95^{\circ}C$ was the best for the printing condition. In addition, in the absence of the chamber, the bending of the specimen was found to be large, and in the case of the chamber, the degree of bending was slightly decreased by 0.05 mm.

• 한국방사선학회논문지
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• 제13권4호
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• pp.565-572
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• 2019

본 연구에서는 야외 방사선투과검사 시 방사선작업종사자의 맞춤형 차폐체 제작을 위해 3D 프린터 필라멘트의 재질 및 두께에 대한 차폐 분석을 수행하였다. MCNPX를 이용한 모의 모사를 통해 복셀 선원 $^{192}Ir$, $^{75}Se$를 선택 후 ICRU Slab Phantom에 차폐체를 부착하고, 선원과 Slab Phantom의 거리를 100 cm으로 설정하였다. 12 개의 차폐물질에 대하여 차폐물질이 없는 경우부터 200 mm 까지 5 mm 단위로 나누어 각 차폐물질별 단위 질량 당 흡수되는 에너지를 평가하였다. 그 결과 모든 방사선투과검사용 감마선원에서 ABS + Tungsten, ABS + Bismuth, PLA + Copper, PLA + Iron 순으로 차폐 효과가 높은 것으로 나타났다. 그러나 납에 비해서는 다소 낮은 차폐 효과를 보였다. 향후 본 연구를 토대로 원자번호와 밀도가 높은 필라멘트 재료에 대한 추가적인 연구가 필요할 것으로 판단된다.

• 한국방사선학회논문지
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• 제16권6호
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• pp.687-695
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• 2022

고 에너지 전자선 치료 시 차폐체로 사용되는 납을 대체할 수 있는 3D 프린터 소재를 찾기 위해 MCNP6 프로그램을 사용하였다. 고 에너지 전자선을 방출하는 선형가속기의 PDD(Percent Depth Dose), Flatness, Symmetry를 측정하고, MCNP6로 선형가속기를 모의 모사 후 비교하여 실측과 모의 모사와의 선원항이 일치함을 확인하였다. 납 차폐체를 모의 모사하여, 흡수선량의 95 % 이상을 차폐할 수 있는 납 차폐체의 적정 두께를 선정하였다. 3 mm 두께의 납 차폐체에 대한 흡수선량 데이터를 기준으로 하여 ABS + W(10%), ABS + Bi(10%), PLA + Fe(10%) 소재들의 1, 5, 10, 15 mm 두께 별로 모의 모사로 분석하여 차폐성능을 분석하였다. 3D 프린터로 각각의 시제품을 제작하여 모의 실험과 같은 조건으로 측정하여 분석한 결과 ABS+W(10%) 소재가 최소 10 mm 이상의 두께로 형성되었을 때, 3 mm 두께의 납을 대체할 수 있는 차폐성능을 가지는 것을 확인하였다. 주사전자현미경(SEM)과 EDS 스펙트럼을 이용하여 ABS + W(10%) 소재의 원소조성 및 표면형상을 분석하였다. 이러한 결과를 통해, 상용화 된 납 차폐체를 ABS + W(10%) 소재로 대체하면 납과 같은 차폐효과를 낼 뿐만 아니라 3D 프린터를 이용하여 환자 맞춤형으로 제작할 수 있어 고 에너지 전자선 치료에 매우 유용할 수 있음을 확인하였다.

• 한국의류산업학회지
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• 제21권3호
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• pp.267-276
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• 2019

This study develops 3D-printed-garment collections for a fashion show presentation. A design concept using traditional patterns that consisted of garments regarding the limitation of the printing technology was investigated in order to develop the collection. The structures of the connecting joints of the textile parts which could be easily and sturdily interconnected were invented. Wearability as garments that could be naturally worn on the human body were sought. As a result, four 3D-printed-garments were developed. The 1st garment composed of objects based on a 'Yeon-Dang-Cho'-pattern was constructed as a geometric robe style using a FDM 3D printer and transparent TPU filaments. The 2nd and 3rd 3D-printed-garments composed of an object based on a 'Boe-Sang-Hwa'-pattern was constructed as a distorted one-piece exaggerating the silhouettes of shoulders and waist parts as well as a straight asymmetric tunic style that used the same printer and material as the 1st garment. The last garment composed of an object based on a 'Boe-Sang-Hwa'-pattern printed using a SLA 3D printer and flexible-liquid-resin was constructed attaching the objects on the fabric material by the hot-press machine. The four developed garments were presented in the opening fashion show of 'the 6th International 3D-printing Korea Expo'. This study provides a basic case for related studies to adapt 3D-printing technology in textile pattern development of garment construction.

• 한국기계가공학회지
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• 제19권11호
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• pp.35-41
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• 2020

The structure of the femur bone was analyzed. Moreover, the mechanical strength of the bone was determined by considering two parameters, namely, the outer wall thickness and inner filling density to realize the 3D printing of a cortical bone and spongy bone by using a fused deposition modeling type 3D printer and ABS material. A basic experiment was conducted to evaluate the variation trend in the mechanical strength of the test specimens with the change in the parameters. Based on the results, the parameters corresponding to the highest mechanical strength were selected and applied to the artificial bone, and the mechanical strength of the artificial bones was examined under a load. Moreover, we proposed an approximation method for the 3D printing parameters to enable the comparison of the actual bones and artificial bones in terms of the strength and weight.

• 대한방사선기술학회지:방사선기술과학
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• 제44권6호
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• pp.615-621
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• 2021

In the medical field, radiation provides information for the diagnosis and treatment of diseases. As the use of radiation increases and the risk of exposure increases, interest in radiation protection is also rapidly increasing. Lead shielding material is mainly used, which has a risk of lead poisoning and absorption into the body. Tungsten mixed filament shielding sheets were fabricated with a size of 70 × 70 mm and a thickness of 1, 2, and 4 mm by using a 3D printer. In the general shooting experiment, the thickness of the shielding sheet is 1 ~ 5mm, the tube voltage is 60, 80, 100, 120 kVp and the tube current is 20, 40 mAs. In general photography, Tungsten showed better shielding rate compared to Brass, Copper, and Lead protective tools under all irradiation conditions, and in particular, Tungsten 5 mm showed 100% shielding rate. The 3D-printed tungsten mixed filament shielding is expected to be used as a new shield that can replace the existing lead protection tools as it shows a better shielding rate than the existing lead protection tools in Radiography.

• 소성∙가공
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• 제31권2호
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• pp.89-95
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• 2022

3D printing products manufactured by material extrusion are used in many industrial fields recently. However, these products are difficult to use in the field due to their low tensile strengths. In order to solve this problem, research on improving the tensile strength of the output using a 3D printer has been continuously conducted. In this study, we performed a tensile test using Universal Testing Machine according to infill pattern, nozzle temperature, bed temperature, and printing speed conditions. Results revealed that tensile specimen of concentric shape had the highest tensile strength in infill pattern condition and that the tensile strength increased linearly with increasing nozzle and bed temperatures. However, the tensile strength decreased with increasing printing speed. Consequently, we confirmed that tensile strength could be increased and decreased depending on output conditions of 3D printing.