• Magazine of RCR
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• v.19 no.1
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• pp.57-60
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• 2024

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.54-59
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• 2020

Coarse aggregate is produced in various ways depending on the location and production method. Currently, the construction industry is in need of a stable supply of coarse aggregate and a way to secure standard quality. The purpose of this study is to examine whether the use of coarse aggregate in 3D printing can help solve this problem. ABS filament was selected for use in 3D printing. CATIA was used for the design of the coarse aggregate, and CUBICON Single Plus was used for the production. Six specimens were produced and cured in water for 28 days. Three of them were made with AE agent, and three were made without it. A compressive strength test confirmed that when the AE agent was used, the compressive strength was greater than the lightweight concrete design criterion specified in the concrete standard specification. This suggests that coarse aggregate produced by a 3D printer may be used for lightweight concrete. A mass production system using this method could help to solve the problems facing the construction industry, such as stable supply and demand for coarse aggregate and securing standard quality.

• Journal of Drive and Control
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• v.17 no.4
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• pp.97-102
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• 2020

This paper presents the basic research for the design and fabrication of a 3D-printed load cell made of NCPC (nano-carbon piezo-resistive composite). We designed a structure that can resonate at a low frequency range of about 5-6 Hz with ANSYS using sensitivity analysis and a response surface method. The design was verified by fabricating the device with a low-quality commercial 3D printer and ABS filament. We conducted a feasibility test for a commercial sensor using 1000 cyclic load tests at 0.3 Hz in a material testing system. A manufacturing process for the 3D printer filament based on the NCPC was also developed using the nano-composite process.

• International Journal of Internet, Broadcasting and Communication
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• v.12 no.3
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• pp.74-86
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• 2020

This study discussesresearch and development of large-sized 3D printers that can be applied to construction and civil engineering for various designs of protective casing on foam liner for concrete exteriors. The consistent use of concrete represents the current surroundings. However, concrete exteriors in Korea have not considered the regional characteristics, but the concrete has been poured solely for economical aspects for the last decade or two. There are many cases of poor installation and not enough design development projects to correct it. This study was conducted to apply various patterns, regional characteristics, and 3D printing for protective casing design for foam liner to create various designs for the concrete walls. Therefore, we started researching on a large 3D printer, and designed and developed this system. Considering the chronological process, the properties of concrete structures were identified, the application of designs for concrete in Korea and abroad and the 3D printing materials for the protective casing were surveyed and analyzed, and a stereotype was produced in the first year to study designs for the beauty of concrete surfaces. In the second year, images of regional characteristics were gathered, design ideas for regional promotion were derived, virtual images were produced along with design modeling to simulate the appearances, and verify the effect of application and promotion. Finally, in the third year, the 3D printer for concrete foam liner was constantly improved to analyze the 3D printing program and the various library elements to complete an actual large-sized 3D printer.

• Korean Journal of Construction Engineering and Management
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• v.21 no.2
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• pp.3-14
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• 2020

This study reviews and comparatively analyzes existing classification systems for 3D concrete printers to propose a classification system for 3D concrete printers. Several classifications for existing 3D printers have been proposed and used in the market. Nevertheless, quite a few of the printer types such as fused deposition modeling (FDM) and selective laser melting (SLM) are not suitable for characterizing 3D concrete printers. To derive the properties that distinguish one 3D concrete printer type from the others, this study reviews existing 3D concrete printers and comparatively analyzes the properties of 3D concrete printers identified in previous studies. The results show that existing classifications do not reflect the states-of-the-art of 3D concrete printers, the classification terms are ambiguous, and the entire printing processes are not considered. A new classification system was proposed based on the essential properties of the 3D concrete printers identified through the analysis of related work. The result of this study can be used as a basis for classifying commercial 3D concrete printers as well as studies related to 3D concrete printers.

• Journal of the Korean Recycled Construction Resources Institute
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• v.6 no.1
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• pp.16-24
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• 2018

In this study, an experiment was conducted to analyze mortar based rheology for 3D printing method application. The tendency of rheological properties due to the change of W/B, binder type, replacement ratio, and super plasticizer which have a great influence on the flow characteristics of concrete was experimentally analyzed. Experiments were carried out by dividing into paste and mortar. In the paste experiment, rheology was analyzed by setting W/B, binder type, replacement ratio, and super plasticizer dosage as main variables. In the mortar experiment, the rheological properties of W/B and sand ratio were analyzed. As a result, as the W/B was increased, the viscosity decreased and the FA ratio to replace FA increased and the viscosity increased. In order to increase the fluidity, substitution of only 5% of SF reduces the shear stress and the viscosity is reduced by about 83%. Mortar rheological evaluation shows that there is a critical section where a large change occurs in the W/B 30 to 40% section. Also, in the same W/B, it is analyzed that there is a critical section where the shear stress increases more than twice in the sand ratio of 50~60%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.305-308
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• 2016

The 3D printing technology which is called new revolution of 21C is under the spotlight recently. The technology takes effects on general manufacturing industries, as well as the prototypes, education, health care, construction. and other industries. It seems that personalized products will be produced and distributed with the introduction of 3D printers. In the case the possibility of violating intellectual property rights, we propose a system that can prevent the violation.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.245-246
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• 2022

Recently, research on the self-healing of concrete using bacteria has been actively conducted. The self-healing method using bacteria has a low self-healing rate and the surrounding environment of the fracture site is very important. A previous study to solve this problem involves the manufacture of capsules using 3D printing. Fracture position control was an important topic in 3D printing-based capsules. In this study, to compensate for the shortcomings of existing studies, a capsule capable of selective destruction location control was produced using PDMS-based molds that are not restricted by the environment. Resin capsules were prepared for each part using several molds and a bonding surface was arranged. In order to verify this on the bonding surface, fracture strength and wave unit values were analyzed through a three-way compression experiment. It can be seen that as the curing time increases, the deviation between samples decreases. In addition, through experiments, it was confirmed that the junction surface and wave unit values coincide in all three directions. It can be used for self-healing research using various solutions.

• Korean Journal of Construction Engineering and Management
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• v.22 no.1
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• pp.81-89
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• 2021

In recent years, the design of buildings is changing from formal to creative and freeform. Accordingly, the scale of construction technology is changing to architectural design and construction of irregular buildings. Using the FDM method, which is one of the 3D printing technologies, it is possible to manufacture various forms of irregular formwork inexpensively and quickly coMPared to the existing formwork, and it seems to be able to solve the manpower problem. Using a 3D printer, the PLA filament formwork is produced in the form of a cylinder and a rectangular cuboid, and the usability of the PLA filament formwork is confirmed by examining the compression strength test and the degree of deformation and reusability over 28 days of age. Different sizes of additional specimens are also conducted according to the size. As a result of the experiment, it was confirmed that the filament formwork itself has about 3~4MPa strength. As a result of reviewing data through existing linear studies and experiments, it is appropriate to use more than 60% infill, and it is advantageous in terms of strength. As a result of cutting and dismantling the filament formwork, the surface is very clean and there is no damage, so it can be reused.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.168-169
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• 2021

A hydrophobic surface increases the contact angle between water and cement paste. There are two methods to increase water contact angle, i.e. lowering the surface energy and adjusting the surface roughness of concrete. The hydrophobicity of concrete can be quantitatively evaluated according to the chemical and physical properties of the solid surface. So far, researches have shown the chemical properties of hydrophobic concrete, however it has not covered how to control surface. This study demonstrated the hydrophobic cement paste prepared by low-resolution molds printed with a 3D printer that exhibit rough surface. Thus, we presented the most hydrophobic characteristics of mold.