• 펄프종이기술
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• 제32권1호
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• pp.1-9
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• 2000

This study was carried out to improve the opacity of printing paper. Conventional filler loading enhanced the opacity of paper, but subsequently caused reduction of paper strength of paper. We try to seek a new filler loading method so-called beater loading that enhances opacity of paper as well as sustained desire strength. In our experiment, comparing to direct loading method, the beater loading method enhanced 0.8% of opacity and 0.2% of brightness. This also decreased the rates of strength reduction of paper. Therefore, the results obtained in this study indicated that beater loading was a very effective method to improve the opacity of paper while not to decreased so much of paper strength.

• Design & Manufacturing
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• 제12권3호
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• pp.19-24
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• 2018

Fused deposition Modeling (FDM) is one of the most widely used for the prototype of parts at ease. The FDM 3D printing method is a lamination manufacturing method that the resin is melted at a high temperature and piled up one by one. Another term is also referred to as FFF (Fused Filament Fabrication). 3D printing technology is mainly used only in the area of prototype production, not in production of commercial products. Therefore, if FDM 3D printer is applied to the product process of commercial products when considered, the strength and dimensional accuracy of the manufactured product is expected to be important. In this study, the mechanical properties of parts made by 3D printing with FDM method were investigated. The aim of this work is to examine how the mechanical properties of the FDM parts, by changing of processing FDM printing direction and the height of stacking layer is affected. The effect of the lamination direction and the height of the stacking layer, which are set as variables in the lamination process, by using the tensile specimen and impact specimen after the FDM manufacturing process were investigated and analyzed. The PLA (Poly Lactic Acid) was used as the filament materials for the 3D printing.

• 대한치과기공학회지
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• 제43권1호
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• pp.13-18
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• 2021

Purpose: This study aimed to compare the flexural properties and perform the Weibull analysis of photo-curing three-dimensional (3D) printing resin. Methods: Photo-curing temporary resin (3D polymer) was used as a printing resin. Specimens (65 × 10 × 3.3 ㎣) were prepared following the ISO 20975-1 guidelines and according to the different printing orientations using a digital light processing 3D printer (D2 120; Dentium). The flexural strength (FS), flexural modulus, and work of fracture (WOF) were measured using a universal testing machine (Instron 3344; Instron) at a crosshead speed of 5 mm/min. Results: In this study, the 0° orientation exhibited higher FS and WOF than the 45° orientation. Significant differences were found among the printing orientations (p<0.05). Specimens printed at the 0° orientation were the most accurate. In the Weibull analysis, 0° showed the greatest Weibull modulus (m), which represents a higher reliability. Conclusion: 3D printing should be selected and used by considering flexural properties, size accuracy, and reliability.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.2160-2163
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• 2005

Solid freeform fabrication (SFF) technology plays a major role in industry and represents a reasonable percentage of industrial rapid prototyping/tooling/manufacturing (RP/RT/RM) development applications. However, SFF technology still has long way to progress to achieve satisfactory process speed, surface finish and overall quality improvement of its application. Today, three dimensional printing (3DP) technique that is one of SFF technology is receiving many interests, and is applied by various fields. It can fabricate three dimensional objects of solid freeform with high speed and low cost using ink jet printing technology. However, need long curing time after manufacture completion. And it must do post-processing process necessarily to heighten strength of objects because strength of fabricated objects is very weak. Therefore, in this study, we proposed an improved 3DP process that can solve problems of conventional 3DP process. The general 3DP process is method to spout binder simply through printer head on powder, but proposed process is method to cure jetted UV resin by UV lamp after jet UV resin using printhead on powder. The hardening of resin is achieved strongly at early time by UV lamp in proposed method. So, the proposed process can fabricate three dimensional objects with high speed without any post-processing.

• 한국분말재료학회지
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• 제31권1호
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• pp.8-15
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• 2024

The emergence of ferrous-medium entropy alloys (FeMEAs) with excellent tensile properties represents a potential direction for designing alloys based on metastable engineering. In this study, an FeMEA is successfully fabricated using laser powder bed fusion (LPBF), a metal additive manufacturing technology. Tensile tests are conducted on the LPBF-processed FeMEA at room temperature and cryogenic temperatures (77 K). At 77 K, the LPBF-processed FeMEA exhibits high yield strength and excellent ultimate tensile strength through active deformation-induced martensitic transformation. Furthermore, due to the low stability of the face-centered cubic (FCC) phase of the LPBF-processed FeMEA based on nano-scale solute heterogeneity, stress-induced martensitic transformation occurs, accompanied by the appearance of a yield point phenomenon during cryogenic tensile deformation. This study elucidates the origin of the yield point phenomenon and deformation behavior of the FeMEA at 77 K.

• 한국기계가공학회지
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• 제17권5호
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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.

• 대한치과보철학회지
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• 제58권4호
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• pp.300-305
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• 2020

목적: 인공치의 표면처리가 3D 프린팅 의치상레진과의 전단결합강도에 미치는 영향을 알아보고 임상적용에 있어 참고하기 위함이다. 재료 및 방법: 3D 프린팅 의치상레진을 3D 프린터를 이용하여 시편을 제작하였고, 인공치의 표면처리는 sandblasting, 프라이머의 적용 유무에 따라 5가지 군으로 나누어, 각 군마다 10개씩 진행하였다. Universal testing machine을 이용하여 전단 결합 강도를 측정하였고, 측정값은 one-way ANOVA로 통계분석 후 Turkey test를 통해 사후검정하였다. 이후 파절된 시편을 주사전자현미경을 이용하여 관찰하였다. 결과: 평균전단결합강도는 표면 처리 하지 않은 군에서 가장 낮은 값을 나타내었으며, 프라이머 처리한 군에서 유의하게 높은 결과 값을 나타내었다(P < .05). 또한 프라이머 처리한 군에서 대부분 응집파절을 나타내었다. 결론: 3D 프린팅 의치상레진에 인공치를 결합 시 인공치의 기계적·화학적 표면처리는 전단결합강도를 증가시켜 3D 프린팅 방식을 사용하여 의치를 제작할 경우 기계적·화학적 표면처리를 통해 인공치의 탈락을 줄일 수 있으며, 특히 sandblasting 과 프라이머를 처리하는 방법이 추천된다.

• 한국건설순환자원학회논문집
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• 제6권3호
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• pp.174-181
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• 2018

본 연구에서는 프린트 층 사이에 부착에 초점을 두고 3D 프린팅 콘크리트의 구조거동 연구를 수행하였다. 3D 프린팅 콘크리트의 부착 및 인장강도 실험을 수행하고 일괄 타설 콘크리트 실험결과와 비교하였다. 실험변수는 콘크리트 층 사이의 프린트 시간차와 철근 보강 여부이다. 콘크리트 층 사이에는 공극이 존재하고 이에 따라, 강도 감소가 발생한다. 층 사이 대부분의 인장부착 강도 감소는 응력 집중과 프린트 시간차에 기인한다. 프린트 시간차가 24시간을 초과할 때 인장부착 강도의 감소는 구조거동에 영향을 미친다. 층 사이 철근 보강은 연성거동 증진에 유용하고 구조물의 갑작스런 파괴를 예방한다. 또한, 공극이 유발한 응력 집중에 기인한 휨 강도 감소는 횡방향 하중을 받는 3D 프린트 벽체 구조물 설계시에 고려되어야 한다.

• 한국인쇄학회지
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• 제29권2호
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• pp.45-58
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• 2011

Gravure off-set printing recently is used in electronics display market. This method has advantages of mass production and high printing speed. It is also fine pattern can be implemented. We have manufactured low-curable conductive Ag pastes for gravure off-set printing. When printing, the pastes be used different silver powder shape because of the printing characteristics. The pastes were prepared with silver powder by silver powder shape and size, epoxy resin, solvent and homogenized on a standard three-roll mill. And the pastes exhibited a shear-thinning flow at viscosity profile. Moreover the adhesive strength and resistivity of silver film had a good characteristics. With the manufactured paste in this study, touch panel had is manufactured and it had $4{\times}10-5{\Omega}.cm$.

• 한국기계가공학회지
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• 제21권5호
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• pp.1-8
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• 2022

Fused deposition modeling (FDM), based on stacking a continuous filament of polymer or composite materials, is well matured and is thus widely used in additive manufacturing technology. To advance FDM-based 3D printing technology, the mechanical properties of additively manufactured composite materials must be improved. In this study, we proposed a novel FDM 3D printing process using metal wire-polymer composites, enabling enhanced mechanical properties. In addition, we developed a new type FDM filament of copper wire wrapped in nylon material for stable 3D printing without thermal damage during the printing process. After FDM printing of the copper wire-nylon composite filament, we conducted a tensile test to investigate the mechanical behavior of the printed composite materials. The experimental results confirmed that the tensile strength of the 3D-printed metal wire-polymer composites was higher than that of the conventional single polymer material. Thus, we expect that the FDM printing process developed in this study may be promising for high-load-bearing applications.