• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.262-265
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• 2004

This study focused on the introduction of the self-healing technique for polymeric composites and evaluated the healing efficiency through the interlainar fracture toughness tests. The DCPD and ENB were used for a healing agent and the Grubbs' catalyst as a catalyst. The healing efficiency was evaluated by the use of mode I and the mode n fracture toughnesses. According to the results, the DCPD-ENB mixture with a suitable ratio revealed better healing efficiency than DCPD only.

• Architectural research
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• v.25 no.3
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• pp.53-59
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• 2023

Concrete is widely used in the construction industry; however, it has the disadvantage of deteriorating durability due to cracks occurring because of climate change and shrinkage. In addition, when cement is used as a binder, CO₂ emitted during the manu-facturing process accounts for ~8% of global CO₂ emissions. In this study, ecofriendly cementitious materials such as blast furnace slag powder and fly ash (FA) were used as cement substitutes in the production of mortar containing a chitosan-based polymer (CP), and their fluidity, compressive strength, and self-healing performance were examined. The 28-day compressive strength of the control sample was ~32.4 MPa (the lowest for all tested samples), while that of the sample containing 5% CP and 20% FA was ~49.6 MPa (the highest for all tested samples) and ~53.1% higher than that of the control sample. Even at a healing age of 56 days, the control sample exhibited the lowest healing performance, whereas the samples containing CP (5%, 10%) and 20% FA demonstrated excellent healing performance. After 28 days, the decrease in crack size for the control sample was minimal; however, for the sample containing only cement and CP, a significant decrease in crack size was observed even after 28 days. This study confirmed that the appropriate use of CP and cementitious materials improves not only compressive strength but also the selfhealing performance of mortar.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.112-119
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• 2020

In this study, cellulose-based bacterial pellets was used for the self-healing concrete manufacturing. The pellet is composed of complex cultured bacterial spore powder, methyl cellulose, two kinds of PVA nutrients and water, and is extruded through a hydraulic press to have a shape of 2mm in diameter to 3 to 4mm in length. Cellulose pellets expand at neutral pH, release bacteria and nutrients, and do not react in a basic environment, increasing the long-term survival rate of bacteria in cement mortar. In addition, pellet self-healing performance of pellet mortar was significantly higher than that of control mortar. Cellulose-based pellets are a new type of bacterial carrier system that will help develop self-healing concrete in the future by improving and optimizing pellets.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.793-796
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• 2003

This study dealt with the manufacturing process of self-healing microcapsules for damage repair in polymeric composites. The microcapsule was consisted with a DCPD (dicyclopentadiene) as the healing agent and a urea-formaldehyde resin as the wall section. The size distribution of microcapsules were measured by a particle size analyzer using a laser diffraction technique. Thermal stability of microcapsules was investigated by using a TGA under continuous and isothermal heating conditions. According to the results, these microcapsules were verified to be to thermally stable and have a great potential to be applicable for damage repair in polymeric composites.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.84-89
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• 2018

Recently, study on self-healing materials have been performed to increase the life by repairing the damage of structures themselves, which are difficult to repair or require high maintenance costs. A water permeability test has been widely used for the evaluation of self-healing performance. However, in the self-healing performance test method, the initial crack width of the concrete greatly affects on the self-healing performance but it does not have a consistent standard. Therefore, in this study, the correlation between crack and permeability and that between time and permeability were analyzed based on crack width and permeability. In addition, since the initial crack width measured by optical microscope is not reliable, the value is derived from the Poiseuille flow and the tendency of time-permeability and time-crack width are analyzed.

• Korean journal of dermatology
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• v.56 no.10
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• pp.645-647
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• 2018

• Elastomers and Composites
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• v.49 no.2
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• pp.134-143
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• 2014

Polymers are introduced to neat asphalt to prepare self-healing asphalt. The polymers are Surlyn, Nylon and polyethyleneterephtalate(PET). Since they are known as having high intermolecular force, they have high processing temperature. Therefore they are hardly introduced into the asphalt as bulk state. So in this study, they are introduced as solutions. Polymer-modified asphalts showed excellent modification effect and also healing effect. 5% polymer added asphalt showed more than 18% increased tensile strength. This tensile strength increment can be explained by polymer's intermolecular forces. Especially Surlyn interacts with asphalt molecules by hydrogen bonding and also with metals in asphalt by ionic bonding. When it comes to healing aspect the healing efficiency of Surlyn increased to 138% based on tensile strength. That of PET increased to 141% based on complex modulus and in case of Nylon it increased to 131% based on impact strength. This tells that in dealing with healing efficiency the important considering factors are not only the intermolecular forces of the polymers but also the interaction between the polymer and asphalt molecules.

• Journal of the Korean Recycled Construction Resources Institute
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• v.11 no.4
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• pp.568-575
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• 2023

This paper aims to evaluate the quality characteristics and healing performance of precast concrete incorporating self-healing technology as a key technique for the construction of smart cities. The study found that precast concrete mixed with hybrid capsules exhibited a tendency of reduced slump and air content, impacting the quality characteristics. Specifically, the slump decreased by up to 14 %, and the air content by up to 9 %. Moreover, the inclusion of hybrid capsules in the concrete resulted in a maximum decrease of 16 % in compressive strength and 18 % in flexural strength. However, the introduction of hybrid capsules significantly enhanced the crack healing performance. The assessment through water permeability tests showed that the healing rate of 0.3 mm crack width after a 28-day healing period improved as the mixing ratio increased, with the healing rates at 1 %, 3 %, and 5 % hybrid capsule mixtures observed to increase by approximately 16 %, 25 %, and 32 %, respectively.

• Journal of Korea Society of Digital Industry and Information Management
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• v.5 no.1
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• pp.23-32
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• 2009

Although the web is becoming a widely accepted medium, it provides relatively poor performance and low availability. A cluster consists of a collection of interconnected stand-alone computers working together and provides a high-availability solution in application area such as web services or information systems. Web server clusters require a high-availability service with a proactive and practical fault management. However, as the system complexity grows, it is not easy to meet the requirement. Therefore, web server clusters must have self-fault management capability for meeting high-availability requirement. In this paper, we propose high availability web server clusters using self-healing technique with a minimal human intervention. Our experimental results show that a proposed method can be used to improve the availability of web server clusters.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2004.04a
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• pp.190-193
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• 2004

Two different diene monomers [dicyclopentadiene (DCPD) and 5-ethylidene-2-norbomene (ENB)] as self­healing agent for polymeric composites were microencapsuled by in-situ polymerization of urea and formaldehyde. The healing agents were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). Exothermic reaction and glass transition temperature from DSC and storage modulus (G') and tan $\delta$ from DMA curves were analyzed for the samples cured for 5 min and 24 h in the presence of different amounts of catalyst. Micorcapsules were successfully formed for both diene monomers. Microcapsules containing the healing agent were manufactured and its thermal properties were characterized by thermo gravimetric analysis (TGA). Optical microscope (OM) and particle size analyzer (PSA) were employed to observe morphology and size distribution of microcapsules, respectively. Comparison of the two self-healing agents and their microcapsules with the two was made in this study.