• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.5
• /
• pp.9-15
• /
• 2023

In this study, the lamination performance and strength characteristics of cement-based composite materials according to the laminated specimens manufacturing method were analyzed. As a result of evaluating the buildability according to the layer height, the highest dimensional stability was shown when the layer height was 10 mm in all parts. The mold casting specimen and the printing-Z specimen showed the same compressive strength performance at the age of 28 days. On the other hand, the compressive strength at 28 day of printing-X specimen was the lowest at 71.72 MPa, and 8% lower than that of the mold casting specimen and the printing-Z specimen. The split tensile strength of the laminated specimen may show similar performance to that of the mold casting specimen, but the strength performance may decrease by more than 10% depending on the direction of the layer and the number of layers in the specimen. As a result of the interface analysis of the laminated specimen through X-ray CT analysis, it was confirmed that pores of a certain size were distributed along the interface of the layer.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.3 no.4
• /
• pp.59-68
• /
• 1997

This study is intended to review the Nucleus System of standard hospitals in U.K. The research is focused on the theoretical background, contents of Nucleus System, and the operational problems through the survey of sample hospitals. The contents of research include the development history of standardization, outlines, aimes, advantages, the data of Nucleus system, and the study-visits of sample hospitals. The conclusion could be summarized as follows ; 1) The form of standard hospitals is compact and low-rise the major movements are horizontal. The standard plans of the functional dpartments are unified as cruciform with $15m{\times}15m$ module. 2) The Nulceus System has been developed. The hospitals have 3 stories maximum and courtyards for natural light & ventilation. 3) The advantages of Nucleus System includes reduction of design & construction period, the buildability due to the repetitive construction, and the running cost. And the disadvantages are mentioned as the lack of storage, staff accomodation, pantry, and sanitary facilities. 4) Sample hospitals provide human scale, possibilities of growth & change, and curing environment from art decoration & artificial lake. 5) In case of Korean situation, even the minimum standardization such as hospital design guidelines should be developed in near future.

• Korean Journal of Construction Engineering and Management
• /
• v.15 no.4
• /
• pp.30-38
• /
• 2014

Achieving high productivity and constructability are very important issues in construction industry. Study on constructability have been conducted actively, and many researches referred that improving constructability can enhance cost, quality, schedule, productivity and so on. However, there are lack of quantitative analysis, since most studies have proved correlation between productivity and constructability using questionaries and by case studies. Also, researches are mostly about specific detail scope of work to improve constructability, thus it is hard to apply constructability factors on various work in construction. In this paper, will deduct general factors affecting on constructability and evaluate effects of factors affecting on each work. Furthermore this paper will verify impact of factors affecting on productivity by multi regression anlaysis using actual data sets of high-rise building construction site.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.35 no.4
• /
• pp.227-233
• /
• 2022

The 3D-printing technique is used for manufacturing objects by adding multiple layers, and it is relatively easy to manufacture objects with complex shapes. The 3D concrete printing technique, which incorporates 3D printing into the construction industry, does not use a formwork when placing concrete, and it requires less workload and labor, so economical construction is possible. However, 3D-printed concrete is expected to have a lower strength than that of molded concrete. In this study, the properties of 3D-printed concrete were analyzed. To fabricate the 3D-printed concrete samples, the extrusion path and shape of the samples were designed with Ultimaker Cura. Based on this, G-codes were generated to control the 3D printer. The optimal concrete mixing proportion was selected considering such factors as extrudability and buildability. Molded samples with the same dimensions were also fabricated for comparative analysis. The properties of each sample were measured through a three-point bending test and uniaxial compression test, and a comparative analysis was performed.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.37 no.1
• /
• pp.33-40
• /
• 2024

The volume of shells, a prominent form of marine waste, is steadily increasing each year. However, a significant portion of these shells is either discarded or left near coastlines, posing environmental and social concerns. Utilizing shells as a substitute for traditional aggregates presents a potential solution, especially considering the diminishing availability of natural aggregates. This approach could effectively reduce transportation logistics costs, thereby promoting resource recycling. In this study, we explore the feasibility of employing wasted shell aggregates in 3D concrete printing technology for marine structures. Despite the advantages, it is observed that 3D printing concrete with wasted shells as aggregates results in lower strength compared to ordinary concrete, attributed to pores at the interface of shells and cement paste. Microstructure characterization becomes essential for evaluating mechanical properties. We conduct an analysis of the mechanical properties and microstructure of 3D printing concrete specimens incorporating wasted shells. Additionally, a mix design is proposed, taking into account flowability, extrudability, and buildability. To assess mechanical properties, compression and bonding strength specimens are fabricated using a 3D printer, and subsequent strength tests are conducted. Microstructure characteristics are analyzed through scanning electron microscope tests, providing high-resolution images. A histogram-based segmentation method is applied to segment pores, and porosity is compared based on the type of wasted shell. Pore characteristics are quantified using a probability function, establishing a correlation between the mechanical properties and microstructure characteristics of the specimens according to the type of wasted shell.