• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.3
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• pp.53-59
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• 2018

When manufacturing self-healing concrete using bacteria, nutrients are added to increase the activity of the bacteria. Although many researches have focused on the effects of nutrients containing bacterial healing agent on concrete, few have studied the effects of sole nutrient on self-healing of cement composites. Bacterial nutrients, like commercial chemical admixtures, affect hydration characteristics such as flow, setting, hydration heat, mechanical strength of cement composites and also affect the self healing of cement composites by hydration of unhydrated particles. In this study, effect of the four nutrient commonly used in the existing literature on the hydration characteristics of cement composites by its addition was investigated. Flow, setting time, hydration heat, compressive strength have studied for each nutrients added by 1.5% and 3% of cement weight. Experimental results shows that urea and calcium-nitrate can be used up to 3% without significant detrimental effect on cement composites. Addition of calcium-lactate up to 1.5% show better compressive strength than control, but addition of 3% show almost non-hydration. Yeast extract shows detrimental effects on the composites regardless of the amount added.

• Journal of People, Plants, and Environment
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• v.23 no.2
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• pp.245-254
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• 2020

Patients diagnosed with cancer face mental problems such as alienation, isolation, anxiety about death and fear, recovering from psychological difficulties. In this study, a forest healing program was provided for cancer patients to recover from psychological stress, depression, social isolation and self-esteem caused by cancer and changes in salivary cortisol through psychological and emotional recovery were measured. From September 19 to November 28, 2017, a forest healing program composed of a total of 10 sessions, two hours per session was provided for 12 cancer patients in the Forest of Taegyo located in Yongin. Psychological tests were performed with Social Adaptation Self-evaluation Scale (SASS), Korean-version Perceived Stress Scale (PSS) and Beck Depression Inventory (BDI) and the collected data were analyzed with the SPSS 18.0. The salivary cortisol level was measured along with the psychological tests and were analyzed by a specialized testing agency. The results of the analysis showed that the pre- and post-assessment score of SASS was 29.17 and 25.92, respectively, and that the pre- and post-assessment score of PSS was 30.50 and 23.92, respectively. The pre- and post-assessment score of BDI was 41.00 and 34.83, respectively, which showed significant differences. In addition, the pre- and post-assessment level of saliva cortisol was 3.13 and 1.68, respectively, showing a significant decrease. In short, the forest healing program was found to be effective in reducing physiological changes caused by social isolation and stress due to the emotional and psychological difficulties that the subjects who were diagnosed with cancer and were recovering from it have. In the future, it will be necessary to develop and implement a forest healing program by conducting a forest healing requirement survey on cancer patients.

• Journal of the Korea Society of Computer and Information
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• v.16 no.9
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• pp.57-68
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• 2011

Self-healing is an approach to evaluating constraints defined in target system and to applying an appropriate strategy when violating the constrains. Today, the computing environment is very complex, so researches that endow a system with the self-healing's ability that recognizes problem arising in a target system are being an important issues. However, most of the existing researches are that self-healing developers need much effort and time to analyze and model constraints. Thus, in order to improve these problems, this paper proposes the method that automatically generates monitoring module by using UML models for self-healing. The approach proposes: 1) defining system knowledge required for self-healing from UML model, 2) process for generating monitor, by using monitor generated, and process for monitoring the problems. Through these, we can reduce the efforts of self-healing developers to analyze target system, and secure monitoring scope based on information of system knowledge. Also we can minimize the efforts to develop the monitoring environment automatically. to evaluate the proposed approach, we apply proposed approach to ATM prototype system for qualitative result, and perform quantitative evaluation through video conference system in our existing research.

• Journal of Soil and Groundwater Environment
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• v.7 no.1
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• pp.41-51
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• 2002

Recently, domestic waste landfills are constructed sometimes on seashore area to provide large landfill area. In order to strengthen the foundation of landfills and to prevent the infiltration of leachate through the bottom, many cases of constructing cement hardened liners on seashore clays are found. In these cases, it is possible to have cracks in the hardened liners due to settlement with waste load since the stiffness of the hardened liner Is greater than that of clay liners. In this study, the capability of Self-Sealing and Self-Healing (SSSH) liner made with a seashore clay in the metropolitan landfill to prevent the percolation of water and leachate is examined using flexible-wall permeameter test and using uniaxial compression test. Applicability of SSSH to weathered granitic soil is also examined for self-sealing capabilities. The result of Flexible permeameter test for SSSH with the seashore clay showed that permeability obtained was lower than permeability criteria of Korean waste management law. The permeability and strength characteristics of SSSH with granitic soil and bentonite showed better results than with the seashore clay.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.309-314
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• 2004

This study focused on the introduction of damage repair for polymeric composite carbody. called selfing tech-healinique. using microcapsules loaded with the healing agent The manufacturing process for microcapsules with the healing agent was introduced and tile characteristics of microcapsules manufactured by varying with various manufacturing process variables were evaluated. The DCPD was used for the healing agent and microcapsules were made of urea-formaldehyde resin. The magnitude and the size distribution of microcapsules were measured by a particle size analyzer using laser diffraction technique. Thermal stability was investigated by using a TGA under continuous and isothermal heating conditions for the healing agent. microcapsules without the healing agent. microcapsules with the healing agent.

• Journal of Adhesion and Interface
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• v.23 no.1
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• pp.8-16
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• 2022

In this study, self-healable waterborne polyurethane (SH-WPU) as shoes and coating materials with self-healable disulfide functionalities was synthesized by mixing polyether polyol to impart excellent durability and heat resistance and polycarbonate polyol to impart excellent mechanical properties. The synthesized SH-WPU was characterized by fourier transform-infrared spectroscopy (FT-IR), and physical and self-healing properties were confirmed through universal testing machine (UTM) and scanning electron microscope (SEM) measurements. Tensile strength and hardness were increased and elongation was decreased by using polycarbonate polyol. In addition, as a result of comparison of thermal properties, thermal stability has been increased as the content of polycarbonate polyol increased. The healing efficiency showed the highest efficiency when poly(tetramethylene ether)glycol : polycarbonate polyol = 0.75 : 0.25, and it was confirmed that the damaged part was healed through surface observation using a microscope and SEM.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.337-341
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• 2004

Engineering ceramics have superior heat resistance, corrosion resistance, and wear resistance. Consequently, these art significant candidates for hot-section structural components of heat engine and the inner containment of nuclear fusion reactor. Besides, some of them have the ability to heal cracks and great benefit can be anticipated with great benefit the structural engineering field. Especially, law fracture toughness of ceramics supplement with self-healing ability. In the present study, we have been noticed some practically important points for the healing behavior of silicon nitride, alumina, mullite with SiC particle and whisker. The presence of silicon carbide (SiC) in ceramic compound is very important for crack-healing behavior. However, self-healing of SiC has not been investigated well in detail yet. In this study, commercial SiC was selected as sample, which can be anticipated in the excellent crack healing ability. The specimens were produced three-point bending specimen with a critical semi-circular crack of which size that is about $50-700{\mu}m$. Three-point bending test and static fatigue test were performed cracked and healed SiC specimens. A monotonic bending load was applied to cracked specimens by three-point loading at different temperature. The purpose of this paper is to report Strength Properties and Elastic Waves Characteristics of Silicon Carbide with Crack Healing Ability.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.122-123
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• 2016

Sulfate anion which cause concrete degradation is affected on marine structures. There are two of control method concrete degradation which is arisen by sulfate anion. Cementitious materials prevent permeation of sulfate anion and water-binder ratio increase to improve watertightness. But, those methods are passive. So, this study is developing new materials which prevent actively concrete degradation on sulfate anion.

• Proceedings of the KIEE Conference
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• 2000.11c
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• pp.522-524
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• 2000

This paper describes the metalization burn out characteristics and spreading-out mechanisms of metalized polypropylene films (MPPF) with defects. As a result, the variation in diameter of the demetalized spots was verified and the spreading-out processes of the demetalized spots were characterized and illustrated by several patterns. Subsequent self healing events was also depicted in this paper.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.215-216
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• 2021

In this study, the liquidity and compressive strength characteristics of concrete mixed with self-healing capsules were analyzed as part of the study to improve the problems of cracks and maintenance of concrete structures.