• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.4
• /
• pp.20-27
• /
• 2021

The present study presents a nonlinear finite element analysis (FEA) approach using the general program of Abaqus to evaluate the seismic response of unreinforced masonry walls strengthened with the steel bar truss system developed in the previous investigation. For finite element models of masonry walls, the concrete damaged plasticity (CDP) and meso-scale methods were considered on the basis of the stress-strain relationships under compression and tension and shear friction-slip relationship of masonry prisms proposed by Yang et al. in order to formulate the interface characteristics between brick elements and mortars. The predictions obtained from the FEA approach were compared with test results under different design parameters; as a result, a good agreement could be observed with respect to the crack propagation, failure mode, rocking strength, peak strength, and lateral load-displacement relationship of masonry walls. Thus, it can be stated that the proposed FEA approach shows a good potential for designing the seismic strengthening of masonry walls.

• The Journal of the Korea Contents Association
• /
• v.21 no.8
• /
• pp.294-304
• /
• 2021

Medical institutions remodel existing hospital buildings rather than construct buildings to satisfy patient satisfaction and enhance competitiveness with other medical institutions. Medical institution remodeling is gradually increasing due to enhanced laws and systems to improve the quality of medical services and the level of patient safety. However, prior studies were discussed only within a limited range, including architectural elements, about medical institution remodeling. Therefore, this study aims to provide basic data to medical institutions planning future remodeling by examining the legal issues of medical institution remodeling in various ways. Medical institution remodeling extends the construction period due to restrictions on construction conditions, and causes damage such as noise and dust to patients. So it is necessary to prevent damage to patients in advance and to support appropriate remodeling of medical institutions. Therefore, it is necessary to prepare an Act on promotion of and support for remodeling of medical institutions. In addition, medical institutions should prepare a checklist for voluntary compliance with construction standards, preventive measures and post-improvement measures, and measures for infection and radiation exposure in hospitals.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.5
• /
• pp.151-160
• /
• 2022

Owing to the recent increase in the frequency of explosion accidents, blast resistive design has garnered attention to reduce the damage of important structural elements. However, domestic research on the blast resistive structures is still insufficient, and domestic design guideline against blast loads are not documented yet. In this study, a numerical study on the RC blast resistive walls, where the test variable was the presence of FRP sheet, was performed using LS-DYNA program. Based on the numerical results, displacement-time hysteretic curve, pressure-impulse diagram, and fragility curve of the test specimens were derived. It was shown that the FRP sheet strengthening method is efficient to improve the blast resistive performance of the RC wall. Also, the strengthening effect of FRP sheet on the RC wall was stronger when the magnitude of the blast load was greater.

• Earthquakes and Structures
• /
• v.22 no.6
• /
• pp.625-635
• /
• 2022

High-rise buildings (HRBs) are considered one of the most common structures nowadays due to the population growth, especially in crowded towns. The lack of land in crowded cities has led to the convergence of the HRBs and the absence of any gaps between them, especially in lands with weak soil (e.g., liquefaction-prone soil), but then during earthquakes, these structures may be exposed to the risk of collision between them due to the large increase in the horizontal displacements, which may be destructive in some cases to the one or both of these adjacent buildings. To evaluate methods of reducing the risk of collision between adjacent twin HRBs, this research investigates three vibration control methods to reduce the risk of collision due to five different earthquakes for the case of two adjacent reinforced concrete (RC) twin high-rise buildings of 15 floors height without gap distance between them, founded on raft foundation supported on piles inside a liquefaction-prone soil. Contact pounding elements between the two buildings (distributed at all floor levels and at the raft foundation level) are used to make the impact strength between the two buildings realistic. The mitigation methods investigated are the base isolation, the tuned mass damper (TMD) method (using traditional TMDs), and the pounding tuned mass damper (PTMD) method (using PTMDs connected between the two buildings). The results show that the PTMD method between the two adjacent RC twin high-rise buildings is more efficient than the other two methods in mitigating the earthquake-induced pounding risk.

• Journal of the Korea Institute of Building Construction
• /
• v.22 no.2
• /
• pp.219-228
• /
• 2022

In this study, to improve educational motivation and learning outcomes, a mobile app using game elements was developed, and the effect of its application in rebar work education was analyzed. Using the 4F(Figure out-Focus-Fun design-Finalize) process, which is a game development model, a mobile learning app for rebar work was developed that considers the characteristics of college students familiar with smartphone use, and the app was developed in a manner that utilizes game mechanics such as learning missions and points to stimulate a learner's interest and improve educational motivation. The results show that the proposed app for rebar work is positively evaluated in terms of interface style, perceived usefulness, perceived ease of use, perceived enjoyment, attitude toward using, and intention to use. Therefore, it can be concluded that using the learning game app for rebar work in classes can contribute to improving a learner's performance in various aspects.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.25 no.4
• /
• pp.1-11
• /
• 2021

The research intended to understand the lateral behavior in core and offset outrigger system. To achieve this goal, a structural analysis and design of 70 stories building was carried out by making use of MIDAS-Gen. And the primary parameters of this analysis were the stiffness of outrigger and the location of outrigger in plan. On the basis of the analysis results, we analyzed the lateral behavior of structural elements such as slab, outrigger and exterior columns in core and offset outrigger. In this analysis research, it is indicated that the stiffness of outrigger and the outrigger location in plan had an any impact on lateral behavior in outrigger system of tall building. Specially, slab stresses in core outrigger system were highly distributed in the slab near the outrigger system to connect shear walls and exterior columns while slab stresses in offset outrigger system were highly distributed in the slab between the outrigger system and shear walls. Also the study results can be of significant help to obtaining the engineering data for the reasonable structure design of the high-rise outrigger system.

• Journal of the Korea Convergence Society
• /
• v.12 no.11
• /
• pp.329-334
• /
• 2021

This thesis examined the characteristics of constructivism that brought about expanded expression of modern jewelry, and also organized how the constructivism was utilized for jewelry. The objective of this study is to examine the attempts of new materials based on constructivism and various expression styles, and also to understand the concept of constructivism developed into an element of complex formative expression. For this, this study organized the characteristics of constructivism that was initially expanded from Bau Haus in the aspect of expression through the composition of material and space, and also analyzed the jewelry artists' methods and attempts to express various materials. As a result, the constructivism showed the expansion of the formativeness of jewelry in the formative aspect of steric expression and in-depth concept through the composition of architectural pattern, visualization of space, and use of other materials, which becomes an example of basic formative element of modern jewelry design. However, it is limited to the material formative element of constructivism, so the expansion of design would be needed. Thus, there should be more researches on the expansion of various jewelry designs that could express the philosophy of constructivism.

• Journal of the Korea Institute of Building Construction
• /
• v.23 no.3
• /
• pp.285-293
• /
• 2023

In this research, we embarked on a meticulous analysis of the challenges inherent in real-world scenarios relating to the durability design standards of engineered concrete structures and the assessment of carbonation durability in concrete guidelines. Our investigation brought to light substantial issues concerning constructability and quality assurance. The genesis of these problems is the exclusive application of prescribed strength to exterior walls, neglecting other elements to facilitate smoother licensing procedures. While this methodology aims to mitigate financial constraints in alignment with enhanced standards, it invariably invites complications. Furthermore, it is imperative to resolve the uncertainty surrounding durability evaluations by establishing a clear and definitive objective. Alongside this, actionable steps must be formulated to forestall the emergence of fissures between the floors of residential buildings, particularly apartment complexes. It is equally essential to tackle issues connected to application by devising a comprehensive management strategy for potential cracking during the phase of maintenance.

• Computers and Concrete
• /
• v.31 no.5
• /
• pp.433-442
• /
• 2023

This study presents the visually observed behavior of fibers embedded in concrete samples that were subjected to a flexural bending test. Three types of fibers such as macro polypropylene, macro polyethylene, and the hybrid of steel and polyvinyl alcohol were mixed with cement by a designated mix ratio to prepare a total of nine specimens of each. The bending test was conducted by following ASTM C1609 with a net deflection of 2, 4, and 7 mm. The X-ray computed tomography (XCT) was carried out for 7 mm-deflection specimens. The original XCT images were post-processed to denoise the beam-hardening effect. Then, fiber, crack, and void were semi-manually segmented. The hybrid specimen showed the highest toughness compared to the other two types. Debonding based on 2D XCT sliced images was commonly observed for all three groups. The cement matrix near the crack surface often involved partially localized breakage in conjunction with debonding. The pullout was predominant for steel fibers that were partially slipped toward the crack. Crack bridging and rupture were not found presumably due to the image resolution and the level of energy dissipation for poly-fibers, while the XCT imaging was advantageous in evaluating the distribution and behavior of various fibers upon bending for fiber-reinforced concrete beam elements.

• Journal of Korean Society of Water and Wastewater
• /
• v.37 no.6
• /
• pp.395-408
• /
• 2023

This study presents a novel method for addressing the issue of high-concentration contaminants (ammonium, phosphate, antibiotics) in leachate arising from decomposing livestock carcasses. Antibiotics, developed to eliminate microorganisms, often have low biodegradability and can persist in the ecosystem. This research proposes design elements to prevent contamination spread from carcass burial sites. The adsorbents used were low-grade charcoal (an industrial by-product), Alum-based Adsorbent (ABA), and Zeolite, a natural substance. These effectively removed the main leachate contaminants: low-grade charcoal for antibiotics (initial concentration 1.05 mg/L, removal rate 73.4%), ABA for phosphate (initial concentration 2.53 mg/L, removal rate 99.9%), and zeolite for ammonium (initial concentration 38.92 mg/L, removal rate 100.0%). The optimal mix ratio for purifying leachate is 1:1:10 of low-grade charcoal, ABA, and zeolite. The average adsorbent usage per burial site was 1,800 kg, costing KRW 2,000,000 per ton. The cost for the minimum leachate volume (about 12.4 m³) per site is KRW 2,880,000, and for the maximum volume (about 19.7 m³) is KRW 4,620,000. These findings contribute to resolving issues related to livestock carcass burial sites and suggest post-management strategies by advocating for the effective use of adsorbents in leachate purification.