• Composites Research
• /
• v.28 no.5
• /
• pp.316-321
• /
• 2015

This study investigated the effects of microcapsules on mechanical properties and thermal stability of the composite material containing self-healing microcapsules. To this end, tensile specimens and flexural specimens containing melamine-urea-formaldehyde (M-U-F) shell walled microcapsules with diameters of $70{\sim}130{\mu}m$ were manufactured. Varying amount of microcapsules in the specimens was considered: 0 wt%, 0.5 wt%, and 1.0 wt%. The tensile and flexural tests were conducted to evaluate mechanical properties of the specimens containing the microcapsules and the thermogravimetric analysis test was performed to evaluate the thermal stability of the specimens containing the microcapsules. The results show that the tensile strength of the specimens was sensitive to the amount of the microcapsules compared to the tensile modulus even though the tensile modulus of the specimens was not significantly affected by the amount of the microcapsules. However, reduction of the tensile strength was not linearly proportional to the amount of microcapsules; similar results were observed in the flexural test. The weight changes of the specimens containing the microcapsules, as a function of temperature, were similar to those specimens without microcapsules. The thermal stability of the specimens was not affected significantly by the microcapsules embedded in the specimens.

• The Journal of the Convergence on Culture Technology
• /
• v.7 no.2
• /
• pp.291-296
• /
• 2021

The purpose of this study is to investigate the effect of gardening programs using vertical gardens on helplessness, depression, and self-esteem in patients with chronic mental disorders. This study was applied to 21 patients with chronic mental disorder who were admitted to the rehabilitation hospital of E Hospital in Seoul from June to October 2018. The group was treated as an experimental group (N = 21) 5 times a week. For 20 weeks, each session lasted 30 minutes. Patients in the experimental group programmed 4 sessions of general occupational therapy, which combined treatments to improve cognition and training, and 1 session of a horticultural program using a vertical garden. Helplessness, depression, and self-esteem were evaluated for pre and post evaluation of the horticultural program. After completing the program, the average score of helplessness in the experimental group decreased by 0.91 points from 47.38 to 46.47, and there was a statistically significant change (p=0.043). The mean score of depression in the experimental group was 9.23 before and after 9.08, which was statistically significant (p = 0.035). The average score of self-esteem in the experimental group increased by 3.14 points from 27.99 to 31.13 at a statistically significant level (p = 0.001). This result suggests that a gardening program using vertical gardens has an effect on helplessness, depression, and self-esteem in patients with chronic mental disorders. And this means that long-term plans and effective programs for recovery from chronic mental disorders to the community are needed. With a horticultural work program using a vertical garden, the helplessness of the mentally impaired in a closed treatment space is restored, and such treatment space needs to be increased.

• Journal of Convergence for Information Technology
• /
• v.9 no.6
• /
• pp.52-64
• /
• 2019

The purpose of this study was to understand and describe the illness experience of middle-aged women who underwent craniotomy for meningioma. Data were collected through individual in-depth interviews with 7 middle-aged women who underwent craniotomy. Verbatim transcripts were analyzed using Giorgi's phenomenological analysis to uncover the meaning of the illness experience of the participants. As a results, seven themes were identified: serious attack of fear in middle age, strengthening self-confidence in healing, escape from fear of death, care for my own body, two types of conflict for family harmony and disease, nurse as a healing partner, and opening the second life. Based on the results of this study, it will be possible to plan more comprehensive nursing intervention through understanding of participants' experience. Also, the main reason of fear that participants felt was lack of information about craniotomy. Therefore, the development of educational programs to provide information and knowledge about cranial surgery is suggested.

• Transactions on Electrical and Electronic Materials
• /
• v.17 no.5
• /
• pp.239-251
• /
• 2016

The potential of nanocomposites have been drawing the intention of the researchers from energy storage to electrical insulation applications. Nanocomposites are known to improve dielectric properties, such as the increase in dielectric breakdown strength, suppressing the partial discharge (PD) as well as space charge, and prolonging the treeing, etc. In this review, different theories have been established to explain the reactions at the interaction zone of polymer matrix and nanofiller; the characterization methods of nanocomposites are also presented. Furthermore, the remarkable findings in the fields of epoxy, cross-linked polyethylene (XLPE), polypropylene and polyvinyl chloride (PVC) nanocomposites are reviewed. In this study, it was observed that there is lack of comparison between results of lab scale specimens and actual field aged cables. Also, non-standardization of the preparation methods and processing parameters lead to changes in the polymer structure and its surface degradation. However, on the positive side, recent attempt of 250 kV XLPE nanocomposite HVDC cables in service may deliver a promising performance in the coming years. Moreover, materials such as self-healing polymer nanocomposites may emerge as substitutes to traditional insulations.

• Journal of Adhesion and Interface
• /
• v.18 no.4
• /
• pp.171-178
• /
• 2017

Recently, layer-by-layer (LbL) assembly has emerged as a promising fabrication technique in controlling surface wetting properties. LbL assembly technique is eco-friendly versatile technique to control the hierarchical structure and surface properties in nano- and micro-scale by employing a variety of materials (e.g., polymers, surfactants, nanoparticles, etc.). This article reviews recent progress in controlling the surface wetting using LbL technique. In particular, technical trends and research findings on fabrication and the applications of superhydrophobic, superhydrophilc, and superoleophobic/superhydrophilic LbL surfaces are extensively explained. Additionally, basic principles and fabrication methods in emerging areas such as omniphobic, self-healing, intelligent and responsive LbL surfaces are discussed.

• Applied Chemistry for Engineering
• /
• v.34 no.3
• /
• pp.207-212
• /
• 2023

Near-infrared (NIR) absorbing dyes have been applied to various applications such as optical filters, biotechnology, energy storage and conversion, coating additive, and traditionally information-storage materials. Because image sensors used in cellphones and digital cameras have sensitivity in the NIR region, the NIR cut-off filter is essential to achieving more clear images. As energy storage and conversion have been important, diverse NIR absorbing materials have been developed to extend the absorption region to the NIR region, and NIR absorbing materials-based research has proceeded to improve device performances. Adding NIR-absorbing dye with a photo-thermal effect to a self-healable coating system has been attractive for future mobility technology, and more effective self-healing properties have been reported. In this report, the chemical structures of representative NIR-absorbing dyes and state of the art research based on NIR-absorbing dyes are introduced.

• The Journal of the Convergence on Culture Technology
• /
• v.3 no.4
• /
• pp.117-122
• /
• 2017

North Korean youth is a youth aged 6 to 18 who lives in a South Korean society after having left North Korea. In this study, photo-in-education (PIE) provides North Korean youths with opportunities for cultural and arts education, and to help them adjust themselves to South Korean society. As a result, they, as young people who are exploring a new life in South Korea, have been able to express their own inner world through photos, videos, and writings. Also, young people have developed a bright and clear mind, and enhanced an expressive power and logical power that helps grow healthily and intelligently. Further, it is the aim of this education to help them to have a positive feeling for society and to do their best to become a healthy member of society, who will be able to contribute to society. Through PIE, it was found that North Korean defectors were able to see themselves positively and express their own inner self positively, despite that they are still in the negative and shady side of life.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.43 no.5
• /
• pp.49-54
• /
• 2011

Curtain coating has been considered as the best coating technology because it is a coating technology that forms contour coating layer with better coverage. To increase the curtain stability surfactants are being used. In this study, the effect of a surfactant on the stability of curtain coating colors was examined by evaluating dynamic surface tension with a bubble surface tensiometer. Di-2-ethylhexyl sodium sulfosuccinate was used as a surfactant since it showed low dynamic surface tension at low surface age. And we evaluated the influence of surfactant on coating color properties including surface tension, viscosity and curtain stability. The surface tension of coating color was decreased when surfactant addition was increased up to 0.5 pph, but it was leveled off at 0.3 pph of surfactant addition. With the increase of surfactant addition rate, viscosity of coating color were increased. Micelles formed by surfactant contributed to the increase of the viscosity. Curtain stability was improved with the addition of surfactant until it reached up to 0.5 pph. Excessive addition of surfactant (> 0.5 pph) didn't improve curtain stability. This was attributed to Marangoni effect(self-healing) and decreasing of curtain thickness.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.35 no.12
• /
• pp.1325-1333
• /
• 2011

An analytical, numerical, and experimental comparison of the hydraulic and thermal performance of new vascular channels with semicircular cross sections was conducted. The following conditions were employed in the study: Reynolds number, 30-2000; cooling channels with a volume fraction of the cooling channels, 0.04; and pressure drop, $30-10^5$ Pa. Three flow configurations were considered: first, second, and third constructal structures with diameters optimized for hydraulic operations. To validate the proposed vascular designs by an analytical approach, 3-D numerical analysis was performed. The numerical model was also validated by the experimental data, and the comparison results were in excellent agreement in all cases. The validation study against the experimental data showed that compared to traditional channels, the optimized structure of the cooling plates could significantly enhance heat transfer and decrease pumping power.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.6
• /
• pp.744-749
• /
• 2013

The protection switching technology is widely adopted in the fiber-optical transmission equipments based on TDM(Time Division Multiplexing), such as PDH, SDH/SONET. A variety of protection switching algorithms for Ethernet networks and the progress of standardization are summarized in the document. There are several kinds of protection switching algorithms for Ethernet networks, such as STP, RSTP, MSTP and etc. However, since Ethernet signal move through detour route, it causes much time to recover. Accordingly, it is difficult to secure a usability of Ethernet networks and QOS(Quality of Service). Also, if the protection switching protocol standardized by IEEE and ITU-T is used, it remains a inherent network switching time for protection. Therefore, a specific protection switching algorithm for Ethernet are needed for seamless and stable operation of Ethernet networks service for Distribution Automation System(DAS). A reliable protection algorithm with no switching delay time is very important to implement Self-healing service for DAS. This study of FPGA based protection switching algorithm for Ethernet networks shows that in case of faults occurrence on distribution power network, immediate fault isolation and restoration are conducted through interaction with distribution equipments using P2P(Peer to Peer) communication for protection coordination. It is concluded that FPGA based protection switching algorithm for Ethernet networks available 0ms switching time is crucial technology to secure reliability of DAS.