• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.1
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• pp.90-97
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• 2024

In this study, we employed Highly Ductile Cement Composite (HDCC) to evaluate the flexural performance of a RC slab that simulates the laminating structure of a seashell. To evaluate flexural performance, we produced conventional RC slab specimens, HDCC slab specimens, and HDCC-M slab specimens which biomimics a seashell's layered structure by inserting PE mesh inside the slab made of HDCC. A series of 4-point bending tests were conducted. Experimental results shows the flexural strength of the HDCC-M slab specimen was 1.7 times and 1.2 times higher than that of the RC and HDCC slab specimens, respectively. Furthermore, the ductility was evaluated using the ratio of yield deflection to maximum deflection, and it was confirmed that the HDCC slab test specimen exhibited the best ductility. This is most likely due to the fact that the inserted PE mesh separates the layers and increases ductility, while the HDCC passing through the mesh prevents the loss of load carrying capacity due to layer separation.

• 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 the Korean Recycled Construction Resources Institute
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• v.6 no.3
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• pp.174-181
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• 2018

This paper examines the structural behavior of 3D printed concrete specimens with focus on the bond between the layers. The tensile bond and flexural strengths were investigated experimentally and compared with those of specimens made by conventional mold casting. The test parameters were the time gap between printing layers and the reinforcement between vertical layers. The results showed the 3D printed specimens had voids between layers and confirmed the strength reduction due to printing time gap and the stress concentration caused by the voids. Most of the reduction in tensile bond strength between layers was due to the stress concentration at least up to certain printing time gap. Moreover, beyond a certain printing time gap (24hours), the additional reduction in tensile bond strength reached a level that could affect the structural behavior. The reinforcement between layers was helpful to increase the ductile behavior which is essential to prevent the sudden collapse of the structure. In addition, the reduction in flexural strength due to the stress concentration by the voids was observed and should be considered in the design of 3D printed wall structures against the lateral load.

• The Journal of Sustainable Design and Educational Environment Research
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• v.19 no.4
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• pp.78-87
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• 2020

This study proposed the basic data that contributes to inducing an effective construction plan through the application of the 4th industrial technology to construct a school building that can guarantee the five goals of construction management: cost, process, quality, safety, and environmental management. To this end, 3D printing, drones, robot automation, and augmented reality technologies that are highly usable in construction sites were identified for construction workers. As part of this, related literature and research data were investigated. The selected 4th industrial technology was investigated and analyzed on how it was used for cost, process, quality, safety, and environmental management in a detailed school construction process. As a result of the analysis, significant results were found for the application plan of the 4th industrial technology in school construction for cost, process, quality, safety, and environmental management.

• Korean Journal of Construction Engineering and Management
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• v.23 no.6
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• pp.119-124
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• 2022

Recently a method of constructing architectural products using additive manufacturing technology has been proposed. The additive manufacturing technology automates the construction process and it can secure the safety of workers. In addition, due to the high implementation efficiency of atypical shapes, the applicability to the manufacturing process of buildings and infrastructure is drawing attention. Additive manufacturing technology has the ability of satisfying computer-based construction automation, resource management and construction period prediction which is required in the modern construction industry. However, the industrial application is still limited by insufficient data, standards, regulations, and operating methods. In this study, in order to analyze the applicability of architectural additive manufacturing technology, we manufacture each architectural product with two additive manufacturing systems. In addition, we apply an application of each building product into an appropriate manufacturing system through the AM production decision model. And identify problems in the manufacturing process through empirical experiments. As a result, we propose an extended additive production decision model to improve the quality of building products.

• Korean Journal of Construction Engineering and Management
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• v.21 no.4
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• pp.72-81
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• 2020

Sustainable development goals (SDGs) are designed to promote human and social development and address challenges related to sustainable economic development, in addition to creating quality employment. SDGs create new market and business opportunities that enable companies to effect business changes through innovative solutions. To tackle structural problems and create infrastructure for future societies, a national-level digital transformation strategy is being developed in Korea. The Korean government announced an investment plan for living social overhead capital (SOC) to address various social and structural problems caused by low economic growth. This study emphasizes the importance of building SOCs in accordance with the requirements of future societies. This study primarily aims to suggest business opportunities created by achieving SDGs, by analyzing business cases involving 3D printing-based construction. Implementing living SOCs through ingenious thinking will not only create new businesses and jobs through digital transformation, but also improve the economic and social value by encouraging community members to be proud of their future society.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.6_2
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• pp.849-860
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• 2021

Recently, it is easy to find cases of 3D printing product, equipment, and materials in the architecture field. However, there is a lack of distribution environment where 3D printing products can be traded on an online platform or to access on-demand services in the architecture field. Therefore, in this study, a distribution platform development plan was proposed in consideration of the maturity level of the 3D printing distribution market in the domestic architecture field. For this purpose, the research was carried out as follows. First, by analyzing the case of the 3D printing distribution platform, the development stage of the distribution platform was set as three stages from the perspective of market maturity, platform development level, and sales/purchase experience level of suppliers and consumers. Second, the market maturity of the current domestic architecture field was evaluated as the first stage, and a distribution platform that could be implemented in the first stage was presented as a pilot. Third, we presented the first stage pilot, collected practical opinions on future construction plans through in-depth interviews, and presented detailed implementation plans for each stage necessary to achieve the second and third stage market maturity goals. Based on the roadmap derived from this study, it is expected that the domestic distribution platform market will grow step by step in the future and be utilized for business model development.

• Journal of Drive and Control
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• v.16 no.3
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• pp.42-50
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• 2019

3D printing AM processes have advantages in complex shapes, customized fabrication and prototype development stage. However, due to various parameters based on both the machine and the material, the AM process can produce finished output after several trials and errors in the initial stage. As such, minimizing or optimizing negative factors for various parameters of the 3D printing AM process could be a solution to reduce the trial-and-error failures in the early stages of such an AM process. In addition, this can be largely solved through software simulation in the preprocessing process of 3D printing AM process. Therefore, the objective of this study was to investigate a simulation technology for the AM software, especially Ansys Inc. The metal 3D printing AM process, the AM process simulation software, and the AM process simulation processor were examined. Through this study, it will be helpful to understand 3D printing AM process and AM process simulation processor.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.73-80
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• 2022

This study evaluated changes in fluidity and rheological properties over time for 3D printed composite materials, and evaluated compressive strength and splitting tensile strength properties for laminated and molded specimens. The composite material for 3D printing starts to change rapidly after 30 minutes of extrusion, and the viscosity of the material tends to be maintained up to 90 minutes, but it was confirmed that construction within 60 minutes after mixing is effective. The compressive strength of the laminated test specimen showed equivalent or better performance at all ages compared to the molded test specimen. In the stress-strain curve of the laminated specimen, the initial slope was similar to that of the molded specimen, but the descending slope was on average 1.9 times higher than that of the molded specimen, indicating relatively brittle behavior. The splitting tensile strength of the P-V laminated specimen was about 6% lower than that of the molded specimen. It is judged that this is because the interfacial adhesion force against the vertical load is affected by the pattern direction of the laminated test specimen.

• 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.