• 한국CDE학회논문집
• /
• 제21권3호
• /
• pp.224-233
• /
• 2016

We propose a new method to visualize 3D models for FDM (Fused Deposition. Modeling) printing that appearance of the printed results can be predicted more realistically as that the efficiency of the modeling-printing process can be improved. The layered nature of horizontal slicing and the vibratory nozzle movements of customer-level FDM 3D printers leaving the characteristic patterns of noisy stripes on the surfaces of printed objects make difficulties in prediction of printed result in company with the thermal contraction of filament material. First, our method analyses the G-codes generated by common slicers to obtain proper outlines and take advantages of a modified version of Perlin noise based texturing method for rendering efficiency and enough number of control parameters on the visual details. The results show improved rendering details of pre-visualization of FDM printing.

• 한국전산구조공학회논문집
• /
• 제35권4호
• /
• pp.227-233
• /
• 2022

3D 프린팅은 다수의 레이어(layer)를 적층하여 물체를 제작하는 기법으로, 복잡한 형상을 가지는 물체를 비교적 쉽게 제작할 수 있다. 이를 건설 산업에 접목한 3D 콘크리트 프린팅(3D concrete printing)은 콘크리트 타설 시 거푸집을 사용하지 않으며, 비교적 적은 작업량과 인력이 요구되므로 경제적인 시공이 가능하나, 출력된 3D 프린팅 콘크리트는 일반 콘크리트 대비 다소 낮은 강도가 예상된다. 따라서, 본 연구에서는 3D 프린팅 콘크리트 시편의 물성을 분석하였다. 3D 프린팅 콘크리트 시편 출력을 위해 Ultimaker Cura 소프트웨어로 형상 및 출력 경로를 설계하고, 이를 바탕으로 3D 프린터를 제어하는 G-code를 생성하였다. 연구에서 사용된 3D 프린터의 출력 성능과 콘크리트의 적층성, 유동성 등을 고려하여 최적의 배합비를 선정하였고, 시편 출력에 활용하였다. 시편 출력 시 동일한 치수를 가지는 몰드 시편을 함께 제작하여 비교·분석에 사용하였다. 각 시편의 물성은 휨강도 시험과 압축강도 시험을 통해 각각의 강도를 측정하였고, 비교·분석하여 3D 프린팅 콘크리트 시편의 물성을 확인하였다.

• 한국전자파학회논문지
• /
• 제16권9호
• /
• pp.926-931
• /
• 2005

본 논문에서는 소형${\cdot}$광대역 특성을 갖는 프린트 슬리브 모노폴 안테나(printed-sleeve monopole antennas)를 제안하고 복사 특성을 고찰하였다. 제안된 안테나의 광대역 특성을 확인하기 위하여 PCS 대역(1.75 GHz${\~}$l.87 GHz)에서 안테나를 설계 제작하고 복사 특성을 측정하였다. 제안된 안테나는 수평면내 무지향성, 수직면내 지향성 특성을 가지며, 정재파비는 사용 주파수 대역에서 1.5이하, 안테나 이득은 2.14 dBi${\~}$3.4 dBi로 나타났다. 측정결과로부터 제안된 안테나는 이동 통신 실내용 광대역 안테나로 널리 사용될 수 있음을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.332-332
• /
• 2010

We have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films withouWe have successfully demonstrated the inkjet printing method to create $Al_2O_3$ films without a high temperature sintering process. In order to remove the coffee ring effect in the ink drop, we have introduced a co-solvent system in order to create Marangoni flow in the ink drop, which leads to the dense packing of ceramic powders on the substrate during inkjet process. The packing density of the Inkjet-printed $Al_2O_3$ films is around 60% (max. 70%) which is very high compared to the value obtained from the same material films by other conventional methods such as film casting, dip coating process, etc. The voids inside the films (which are around 40% of the entire film volume) are filled with the polymer resin (Cyanate ester) by the infiltration process. This resin infiltration is also implemented by the inkjet printing process right after the Ah03 film ink-jetting process. The microstructures of the printed $Al_2O_3$ films are investigated by Scanning Electron Microscope (SEM) to understand the degree of packing density in the printed films. The inkjet-printed $Al_2O_3$ films have been characterized to investigate its thickness and roughness. Quality factor of the printed $Al_2O_3$ film is also measured to be over 300 at 1MHz.

• 한국산업융합학회 논문집
• /
• 제26권5호
• /
• pp.937-943
• /
• 2023

In this study, the mast cover of submarine was reverse engineered and structural analysis was performed. In order to print with the 3D printer, the modeling was reduced to 1/5 size by applying geometric similarity. From the structural analysis results, it was found that the maximum value of equivalent stress generated in the mast cover was 180.9 MPa. This stress value occurs on the inner surface in the major axis. As a result of applying the load condition at a diving depth of 600 m, the mast cover is in a completely elastic state. The 1/5 size model printed on FDM 3D printer with PLA filament was the same as the reverse engineered modeling and it was printed in a perfect shape with no apparent defects. The 1/5 size model printed on PBF 3D printer with SUS316L powder was perfectly manufactured with no apparent defects.

• The Journal of Advanced Prosthodontics
• /
• 제13권2호
• /
• pp.71-78
• /
• 2021

Purpose. This study aims to compare the volumetric change, degree of conversion (DOC), and cytotoxicity of 3D-printed restorations post-cured under three different conditions. Materials and Methods. 3D-printed interim restorations were post-cured under three different conditions and systems: 5 min, 30 min, and 24 h. Three-unit and six-unit fixed dental prostheses (n = 30 for each case) were printed; ten specimens from each group were post-cured and then scanned to compare their volumetric changes. Root-mean-squared (RMS) values of the data were acquired by superimposing the scanned files with original files. Thirty disk-shaped specimens were printed to evaluate the DOC ratio. Fourier transform infrared spectroscopy was used to compare the DOCs of 10 specimens from each group. Human gingival fibroblasts were used to measure the cell viability of every specimen (n = 7). The data from this experiment were employed for one-way analysis of variance and Tukey's post-hoc comparisons. Results. Differences between the three-unit restorations were statistically insignificant, regardless of the post-curing conditions. However, for the six-unit restorations, a high RMS value was acquired when the post-curing duration was 30 min. The average DOC was approximately 56 - 62%; the difference between each group was statistically insignificant. All the groups exhibited cell viability greater than 70%, rendering them clinically acceptable. Conclusion. The post-curing conditions influenced the volume when the length of the restoration was increased. However, this deviation was found to be clinically acceptable. Additionally, post-curing did not significantly influence the DOC and cytotoxicity of the restorations.

• The Journal of Advanced Prosthodontics
• /
• 제14권4호
• /
• pp.250-261
• /
• 2022

PURPOSE. The purpose of this study was to analyze the marginal fit of three-unit resin prostheses printed with the stereolithography (SLA) method in two build orientations (45°, 60°) and two layer thicknesses (50 ㎛, 100 ㎛). MATERIALS AND METHODS. A master model for a three-unit resin prosthesis was designed with two implant abutments. Forty specimens were printed using an SLA 3D printer. The specimens were printed with two build orientations (45°, 60°), and each orientation was printed with two layer thicknesses (50 ㎛, 100 ㎛). The marginal fit was measured as the marginal gap (MG) and absolute marginal discrepancy (AMD), and MG and AMD measurements were performed at 8 points per abutment, for 16 points per specimen. All statistical analyses were performed using SPSS software. Two-way analysis of variance (ANOVA) was separately performed on the MG and AMD values of the build orientations and layer thicknesses. Moreover, one-way ANOVA was performed for each point within each group. RESULTS. The margins of the area adjacent to the pontic showed significantly high values, and the values were smaller when the build orientation was 45° than when it was 60°. However, the margin did not differ significantly according to the layer thicknesses. CONCLUSION. The marginal fit of the three-unit resin prosthesis fabricated by the SLA 3D method was affected by the pontic. Moreover, the marginal fit was affected by the build orientation. The 45° build orientation is recommended.

• 대한토목학회논문집
• /
• 제39권2호
• /
• pp.345-349
• /
• 2019

미국항공우주국은 인류의 타 행성 거주 가능성에 대해 지속적으로 관심을 가지고 관련 연구들을 진행해오고 있다. 이에 대한 관심을 고무시키기 위해 다양한 국제 대회를 추진하여 관련 아이디어를 공유하고 정보를 모으는데 기여하고 있다. NASA Centennial Challenge Program 중 한 가지인 "3D-Printed Habitat Challenge"는 2015년과 2017에 1차, 2차 대회를 진행한 바 있으며, 현재 3차 대회를 진행 중에 있다. 본 연구진은 지난 2차 대회 참가 경험과 해외 협력을 통해 3차 대회를 진행하고 있으며 대회 참가 및 건설 자동화 시공을 위하여 건설용 3D-Printer에 적용 가능한 사출 모듈을 개발하였다. 3D 프린팅 사출 모듈과 한국에서 최초로 개발된 달 복제토 KOHLS-1, 플라스틱 폴리머를 재료로 적층식 공시체를 제작하였다. 또한 3D 프린팅을 활용한 건설 기술의 핵심인 사출 모듈을 최적화하는 과정에서 ${\varnothing}150{\times}300mm^3$ 부피의 원기둥 공시체와 $200{\times}100{\times}650mm^3$ 부피의 보 공시체의 압축강도 및 휨 강도 시험을 진행하였다.

• 반도체디스플레이기술학회지
• /
• 제18권3호
• /
• pp.25-30
• /
• 2019

In this paper, we have analyzed manufacturing problems of the scaffold with pores using FDM 3D printer and PLGA. We suggested the solutions using 3SC practical TRIZ. We selected the final solution used machine learning. We reduced number of experiments using most influential factor after analysis print factors. We printed the scaffold and measured pore size. We created the regression model using python tensorflow. The print condition data of measured pore size was used as training data. We predicted the pore size of printed condition using regression model. We printed the scaffold using the predicted the print condition data. We quantitatively compare the predicted scaffold pore size data and the measured scaffold pore size data. We got satisfactory result.

• 국제학술발표논문집
• /
• The 8th International Conference on Construction Engineering and Project Management
• /
• pp.75-84
• /
• 2020

Modular construction is a construction method whereby prefabricated volumetric units are produced in a factory and are installed on site to form a building block. The construction productivity can be substantially improved by the manufacturing and assembly of standardized modular units. 3D printing is a computer-controlled fabrication method first adopted in the manufacturing industry and was utilized for the automated construction of small-scale houses in recent years. Implementing 3D printing in the fabrication of modular units brings huge benefits to modular construction, including increased customization, lower material waste, and reduced labor work. Such implementation also benefits the large-scale and wider adoption of 3D printing in engineering practice. However, a critical issue for 3D printed modules is the loading capacity, particularly in response to horizontal forces like wind load, which requires a deeper understanding of the building structure behavior and the design of load-bearing modules. Therefore, this paper presents the state-of-the-art literature concerning recent achievement in 3D printing for buildings, followed by discussion on the opportunities and challenges for examining 3D printing in modular construction. Promising 3D printing techniques are critically reviewed and discussed with regard to their advantages and limitations in construction. The appropriate structural form needs to be determined at the design stage, taking into consideration the overall building structural behavior, site environmental conditions (e.g., wind), and load-carrying capacity of the 3D printed modules. Detailed finite element modelling of the entire modular buildings needs to be conducted to verify the structural performance, considering the code-stipulated lateral drift, strength criteria, and other design requirements. Moreover, integration of building information modelling (BIM) method is beneficial for generating the material and geometric details of the 3D printed modules, which can then be utilized for the fabrication.