• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.404-412
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• 2020

Herein, the properties and self-healing performance of cement mortar incorporating calcium sulfoaluminate(CSA), crystalline admixture(CA), and magnesium oxide(MgO) were investigated. Mortar strength test and water permeability experiments were conducted to analyze self-healing performance of the mortar. Also, variation in crack width were measured via digital optical microscope observation. The hydration products formed in the crack via self-healing were analyzed using x-ray diffraction(XRD), thermogravimetry(TG), and digital optical microscope. The analysis revealed that compressive strength and tensile strength increased as CA substitutional ratio increased. However, in the case of MgO replacement, the compressive strength and tensile strength decreased as the CA substitution ratio increased. The products in the recovered cracks are found to be mostly Ca(OH)2, MgCO3, and CaCO3. CaCO3 was shown to be the main healing product and had a higher portion than Ca(OH)2 and MgCO3 in the recovery products. Moreover, the optimal mix derived via water permeability and crack width results was 8% CSA + 1% CA + 2.5% MgO.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.1
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• pp.81-87
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• 2020

Crack control is essential to increase the durability of concrete significantly. Healing of crack can be controlled by rehydration of unreacted clinkers at the crack surface. In this paper, by comparing the results of isothermal calorimetry test and regression analysis, the Parrot & Killoh's cement hydration model was verified and clink er hydration model was proposed. The composition and quantification of hydration products were simulated by combining kinematic hydration model and thermodynamic model. Hydration simulation was conducted using the verified and proposed hydration model, and the simulation was performed by the substitution rate of clink er. The type and quantity of the final hydration product and healing product were predicted and, in addition, the optimal cementitious material of self-healing concrete was selected using the proposed hydration model.

• Journal of Digital Convergence
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• v.16 no.6
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• pp.297-306
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• 2018

The purpose of this study was to examine the effectiveness of a smoking cessation healing camp for male workers. A single group pre-test post-test design was used. An experimental group (n=28) allocated into a smoking cessation healing camp which was provided for two days and one night. Effectiveness of the intervention was measured at soon after smoking cessation healing camp. There were significant differences between pre-test and post-test on readiness to quit smoking(t=-2.64, p=.013), smoking cessation self-efficacy(t=2.42, pp=.022), nicotine dependence(t=2.55, p=.017), and depression(t=2.85, p=.008). In conclusion, the smoking cessation healing camp is effective for male smokers in workplace settings by providing insightful antismoking information and encouraging smoking cessation self-efficacy and readiness to quit smoking.

• Clean Technology
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• v.17 no.1
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• pp.1-12
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• 2011

Scientists and engineers have altered the properties of materials such as metals, alloys, polymers, ceramics, and so on, to suit the ever changing needs of our society. Man-made engineering materials generally demonstrate excellent mechanical properties, which often tar exceed those of natural materials. However, all such engineering materials lack the ability of self-healing, i.e. the ability to remove or neutralize microcracks without intentional human interaction. The damage management paradigm observed in nature can be reproduced successfully in man-made engineering materials, provided the intrinsic character of the various types of engineering materials is taken into account. Various self-healing ptotocols that can be applied for the organic materials such as polymers, ionomers and composites can be developed by utilizing suitable chemical reactions and physical intermolecular interactions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.2
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• pp.79-87
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• 2011

In this study, the chloride penetration tests were performed for the initially cracked reinforced concrete members. The chloride diffusion characteristics and the critical crack width are compared, and the properties of self-healing are investigated. According to the test results, the chloride penetration resistance was greatly reduced as the surface crack width increased. When the mineral admixtures are added, the chloride penetration resistance of uncracked specimens were effectively increased, however, in case of the blast furnace slag and fly ash, the cracked specimens showed the more reduced resistance than OPC case, inversely. Also, the critical width was $29{\mu}m$, on average, for immersion test. The crack width with $4{\sim}15{\mu}m$ was restored by self-healing, The parts restored by self-healing were seemed to be visually restored, however, the chloride penetration resistance was not restored, perfectly.

• Journal of the Korean Geotechnical Society
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• v.32 no.3
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• pp.29-37
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• 2016

SSG (self-healing smart grouting) method, which is developed recently, has the characteristics such as an improvement of durability and waterproofing, prevention of leaching and pollution. In this study, we performed several tests such as gel-time measurement, uniaxial compression test, permeability test, fish poison test and chemical resistance test to compare the engineering properties of SSG with the other chemical grouting method (LW, SGR). As results of tests, the SSG method has low possibility of groundwater and ground pollution caused by leaching, furthermore, it has advantages like long/short term waterproofing, strength and durability. Therefore the SSG method can be applicable in the fields as an alternative of existing chemical grouting methods with problems.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.9
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• pp.199-206
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• 2019

Experimental study on the durability characteristics to examine the feasibility of concrete with high water-tightness and self-healing performance to minimize maintenance of concrete for artificial ground is as follows. 1) When blending agent, swelling agents, and curing accelerator were added on the ternary system cement with blast-furnace slag fine particles and fly ash to give a self-healing property, higher blending strengths by 82% at design standard strength of 24MPa and by 74% at design strength of 30MPa, respectively could be obtained. 2) The permeability test for the specimens having high water-tightness and no shrinkage showed that the permeability was reduced at maximum of 98%. However, the permeability was decreased as the design strength was increased, showing the reduction rate of 87% at the design strength of 50MPa. 3) The depth of carbonation of blast-furnace slag and fly ash was increased in all the specimens compared with those of OPC only. However, as the material age was increased, carbonation penetration depth was decreased compared with the reference blend. 4) Compared with the reference blending using only OPC, the freeze-thaw resistance was higher in the case of blending with 40% of blast-furnace slag and 10% of fly ash at the design standard strength of 50MPa. In addition, the freeze-thaw resistance in general was superior in the design standard strength of 50MPa with the lower water-binder ratio (W/B) as compared with the design standard strength of 24MPa and 30MPa with the high water-binder ratios.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.243-244
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• 2022

In this paper, experiments were conducted on signal amplification of polymer capsules for application to Ground Penetrating Radar so as to enable real-time monitoring of polymer capsules inside concrete using the Morphology Dependent Resonance phenomenon. A TEM CELL and a vector network analyzer were used to analyze the difference in resonance frequency depending on the material of the sphere and the presence or absence of fracture. In order to manufacture a capsule of a size that can be measured using millimeter waves used in GPR, we manufactured a capsule with a 3D printer and analyzed the effects of the presence or absence of coating and the size of the capsule on the resonance frequency. Resonant frequency or signal amplification is more affected by diameter than coating. The capsule showing the highest amplification is the resin-coated 50 mm diameter capsule with a 316-fold increase and the lowest capsule is the uncoated 10 mm diameter capsule with a signal amplification of 11.9 times. These results demonstrate the potential of GPR to measure the position and state of self-healing capsules, which are small-sized polymers, in real time using millimeter waves.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.508-511
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• 2004

This study focused on the effect of autonomic microcapsules on the mechanical properties of structural material. Several types of microcapsules with healing agents were manufactured by varying agitation speed of high speed stirrer. The size distribution of microcapsules was measured by a particle size analzer. The epoxy specimens embedded with microcapsules were manufactured and the degree of cure of such epoxy specimen was measured by a differential scanning calorimetry. The tensile modulus and tensile strength in epoxy specimens embedded with microcapsules were evaluated in order to investigate the effects of microcapsules on mechanical properties of structural materials. The configuration of microcapsules and morphology of fracture surfaces for the epoxy specimen were examined by an optical microcope and a scanning electron microscope. According to the results, tensile strength of the epoxy specimen embedded with microcapsules was indicated a little reduction, but tensile modulus was not much affected on microcapsules.

• Journal of The Korea Institute of Healthcare Architecture
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• v.11 no.2
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• pp.63-71
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• 2005

The purpose of this study is to find the complementary idea of the psychological elements in aesthetic expression of architectural space in the sense of healing. Marks $L\ddot{u}scher$, the swiss psychologist suggested reasonable categories of emotional character according to the couple combinations among Content, Self-Esteem, Confidence, and Liberty. His theory on healing is not only the concept but the practical method to understand and control the conflict between contrary elements of emotion. Compared to the Freud's objective theory of cause and consequence, his idea is focused on the subjective and autonomous harmony. This theory based on complementary idea is applied to psychological attitude of architects on Spatial Expression in this study. Refuge, Prospect, Flow and Void are assumed as equivalent spatial elements to the four major emotional conditions suggested by $M.L\ddot{u}scher$. The couple combinations among them also characterize the architectural characters definitely and it is expected to be the reasonable criteria in analysing aesthetic value and motive of creating human space.