• Title/Summary/Keyword: Loss and damage

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Self-healing and leakage performance of cracks in the wall of a reinforced concrete water tank

  • Gao, Lin;Wang, Mingzhen;Guo, Endong;Sun, Yazhen
    • Earthquakes and Structures
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    • v.16 no.6
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    • pp.727-741
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    • 2019
  • A reinforced concrete water tank is a typical functional liquid storage structure and cracks are the greatest threat to the liquid storage structure. Tanks are readily cracked due to seismic activity, thereby leading to the leakage of the stored liquid and a loss of function. In order to study the effect of cracks on liquid storage tanks, self-healing and leakage tests for bending cracks and through cracks in the walls of a reinforced concrete water tank were conducted. Material performance tests were also performed. The self-healing performance of bending cracks in a lentic environment and through cracks in a lotic environment were tested, thereby the self-healing width of bending micro-cracks in the lentic environment in the short term were determined. The through cracks had the capacity for self-healing in the lotic environment was found. The leakage characteristics of the bending cracks and through cracks were tested with the actual water head on the crack. The effects on liquid leakage of the width of bending cracks, the depth of the compression zone, and the acting head were determined. The relationships between the leakage rate and time with the height of the water head were analyzed. Based on the tests, the relationships between the crack characteristics and self-healing as well as the leakage were obtained. Thereby the references for water tank structure design and grading earthquake damage were provided.

A Study for Efficient Foreign Object Debris Detection on Runways (활주로 FOD 탐지 효율화를 위한 기술적 고찰)

  • Lee, Kwang-Byeng;Lee, Jonggil;Kim, Donghoon
    • Journal of the Korean Society for Aviation and Aeronautics
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    • v.22 no.1
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    • pp.130-135
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    • 2014
  • FOD(Foreign Object Debris) has the potential threat to damage aircraft during critical phases of take-off and landing roll with some objects including metal on the runway. FOD can be found anywhere on an airport's air operation areas such as runway, taxiway and apron. It can lead to catastrophic loss of life and airframe, and increased maintenance and operating costs. In this paper, we defined FOD and surveyed its riskiness and necessity of automatic FOD detection system. We compared the requirements of the environment in Korea to the FAA advisory circular. Also we analyzed operation methods of FOD detection systems already installed at some airports. Based on the surveys mentioned above, we propose hybrid type of FOD detection system considering the environment in Korea which uses millimeter wave radar, optical camera and thermal imaging camera to detect FOD efficiently. In management approach, fixed type of the system should be installed for real-time monitoring, and mobile type of the system can be used additionally.

Nonlinear spectral design analysis of a structure for hybrid self-centring device enabled structures

  • Golzar, Farzin G.;Rodgers, Geoffrey W.;Chase, J. Geoffrey
    • Structural Engineering and Mechanics
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    • v.61 no.6
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    • pp.701-709
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    • 2017
  • Seismic dissipation devices can play a crucial role in mitigating earthquake damages, loss of life and post-event repair and downtime costs. This research investigates the use of ring springs with high-force-to-volume (HF2V) dissipaters to create damage-free, recentring connections and structures. HF2V devices are passive rate-dependent extrusion-based devices with high energy absorption characteristics. Ring springs are passive energy dissipation devices with high self-centring capability to reduce the residual displacements. Dynamic behaviour of a system with nonlinear structural stiffness and supplemental hybrid damping via HF2V devices and ring spring dampers is used to investigate the design space and potential. HF2V devices are modelled with design forces equal to 5% and 10% of seismic weight and ring springs are modelled with loading stiffness values of 20% and 40% of initial structural stiffness and respective unloading stiffness of 7% and 14% of structural stiffness (equivalent to 35% of their loading stiffness). Using a suite of 20 design level earthquake ground motions, nonlinear response spectra for 8 different configurations are generated. Results show up to 50% reduction in peak displacements and greater than 80% reduction in residual displacements of augmented structure compared to the baseline structure. These gains come at a cost of a significant rise in the base shear values up to 200% mainly as a result of the force contributed by the supplemental devices.

Potential in vitro Protective Effect of Quercetin, Catechin, Caffeic Acid and Phytic Acid against Ethanol-Induced Oxidative Stress in SK-Hep-1 Cells

  • Lee, Ki-Mo;Kang, Hyung-Sik;Yun, Chul-Ho;Kwak, Hahn-Shik
    • Biomolecules & Therapeutics
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    • v.20 no.5
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    • pp.492-498
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    • 2012
  • Phytochemicals have been known to exhibit potent antioxidant activity. This study examined cytoprotective effects of phytochemicals including quercetin, catechin, caffeic acid, and phytic acid against oxidative damage in SK-Hep-1 cells induced by the oxidative and non-oxidative metabolism of ethanol. Exposure of the cells to excess ethanol resulted in a significant increase in cytotoxicity, reactive oxygen species (ROS) production, lipid hydroperoxide (LPO), and antioxidant enzyme activity. Excess ethanol also caused a reduction in mitochondrial membrane potential (MMP) and the quantity of reduced glutathione (GSH). Co-treatment of cells with ethanol and quercetin, catechin, caffeic acid and phytic acid significantly inhibited oxidative ethanol metabolism-induced cytotoxicity by blocking ROS production. When the cells were treated with ethanol after pretreatment of 4-methylpyrazole (4-MP), increased cytotoxicity, ROS production, antioxidant enzyme activity, and loss of MMP were observed. The addition of quercetin, catechin, caffeic acid and phytic acid to these cells showed suppression of non-oxidative ethanol metabolism-induced cytotoxicity, similar to oxidative ethanol metabolism. These results suggest that quercetin, catechin, caffeic acid and phytic acid have protective effects against ethanol metabolism-induced oxidative insult in SK-Hep-1 cells by blocking ROS production and elevating antioxidant potentials.

An Overview of New Progresses in Understanding Pipeline Corrosion

  • Tan, M. YJ;Varela, F.;Huo, Y.;Gupta, R.;Abreu, D.;Mahdavi, F.;Hinton, B.;Forsyth, M.
    • Corrosion Science and Technology
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    • v.15 no.6
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    • pp.271-280
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    • 2016
  • An approach to achieving the ambitious goal of cost effectively extending the safe operation life of energy pipeline to 100 years is the application of health monitoring and life prediction tools that are able to provide both long-term remnant pipeline life prediction and in-situ pipeline condition monitoring. A critical step is the enhancement of technological capabilities that are required for understanding and quantifying the effects of key factors influencing buried steel pipeline corrosion and environmentally assisted materials degradation, and the development of condition monitoring technologies that are able to provide in-situ monitoring and site-specific warning of pipeline damage. This paper provides an overview of our current research aimed at developing new sensors and electrochemical cells for monitoring, categorising and quantifying the level and nature of external pipeline and coating damages under the combined effects of various inter-related variables and processes such as localised corrosion, coating cracking and disbondment, cathodic shielding, transit loss of cathodic protection.

Disease model organism for Parkinson disease: Drosophila melanogaster

  • Aryal, Binod;Lee, Youngseok
    • BMB Reports
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    • v.52 no.4
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    • pp.250-258
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    • 2019
  • Parkinson's disease (PD) is a common neurodegenerative disorder characterized by selective and progressive loss of dopaminergic neurons. Genetic and environmental risk factors are associated with this disease. The genetic factors are composed of approximately 20 genes, such as SNCA, parkin, PTEN-induced kinase1 (pink1), leucine-rich repeat kinase 2 (LRRK2), ATP13A2, MAPT, VPS35, and DJ-1, whereas the environmental factors consist of oxidative stress-induced toxins such as 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP), rotenone, and paraquat. The analyses of their functions and mechanisms have provided important insights into the disease process, which has demonstrated that these factors cause oxidative damage and mitochondrial dysfunction. The most invaluable studies have been performed using disease model organisms, such as mice, fruit flies, and worms. Among them, Drosophila melanogaster has emerged as an excellent model organism to study both environmental and genetic factors and provide insights to the pathways relevant for PD pathogenesis, facilitating development of therapeutic strategies. In this review, we have focused on the fly model organism to summarize recent progress, including pathogenesis, neuroprotective compounds, and newer approaches.

A Study on the Problems and Its Improvement Plans in Operation of Korean Trade Finance System (무역금융제도의 운용상 문제점과 그 개선방안에 관한 연구)

  • Chae, Jing-Ik
    • Korea Trade Review
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    • v.44 no.6
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    • pp.39-54
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    • 2019
  • Trade finance promotes export performance, and every small- and medium-sized export business has the right to use policy finance. The credit line is also stipulated by relevant laws and regulations. However, trade finance has repeatedly been misused, so these matters can lead to substantial financial loss and damage to the related financial institutions. The lack of expertise of K-SURE and the backwardness of banks represent even bigger problems in the follow-up management. The existing trade finance system should be improved in the following ways from the institutional and legal perspectives. Firstly, follow-up management of beneficiary companies should be reinforced and systematized through examining business tendencies, financial status, and other important factors. There is also a need for advancement of following up management. An effective and streamlined financing system must be established by abolishing the Korea Trade Insurance Corporation. This study presents improvements and their implications by looking into the main issues under the current trade finance system. This study is based on documentary research and practical cases.

Dose Effect of Phytosanitary Irradiation on the Postharvest Quality of Cut Flowers

  • Kwon, Song;Kwon, Hye Jin;Ryu, Ju Hyun;Kim, Yu Ri
    • Journal of People, Plants, and Environment
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    • v.23 no.2
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    • pp.171-178
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    • 2020
  • The present study was conducted to determine the effects of electron beam irradiation on the postharvest quality of cut flowers. Cut flowers were irradiated with electron beam at 100, 200, 400, 600, 800, 1,000, and 2,000 Gy with a 10 MeV linear electron beam accelerator to evaluate their irradiation tolerance. Postharvest quality was determined by monitoring fresh weight loss, flower longevity, flower diameter, flowering rate, visual quality of flowers and leaves, and chlorophyll content. Cut flowers showed a radiation-induced damage with increasing the irradiation dose. Flower longevity and fresh weight of cut flowers decreased when the irradiation dose was increased. Flower bud opening was also inhibited in a dose-dependent manner. The effective irradiation doses for 10% reduction of postharvest quality (ED10) values were 144.4, 451.6, and 841.2 Gy in the 'Medusa' lily, 'Montezuma' carnation, and 'Rosina White' eustoma, respectively. Although tolerance of cut flowers to electron beam irradiation vary according to species, cultivars, or maturity stage conditions, it is conceivable that 'Montezuma' carnation and 'Rosina White' eustoma could be tolerated and maintained overall postharvest quality up to 400 Gy, the generic irradiation dose approved by the Animal and Plant Health Inspection Service (APHIS) and the International Plant Protection Convention (IPPC) for postharvest phytosanitary treatments.

A Study on Architectural Form of Waste to Energy Plants in accordance with Law - Focus on Seoul and Tokyo - (법규에 따른 자원회수시설의 건축적 형태에 관한 연구 - 서울과 도쿄를 중심으로 -)

  • Jung, Seung-won;Lee, Kang-jun
    • Journal of Urban Science
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    • v.11 no.1
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    • pp.29-35
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    • 2022
  • Waste to Energy Plant were recognized as hateful facilities, and there were many conflicts in the location due to social problems such as the NIMBY phenomenon due to problems such as damage to property in the surrounding area, odor, and image loss. Problems such as air pollution and odor are solved by the development of advanced prevention facilities such as electric dust collectors, wet cleaning systems, semi-dry reaction towers, bag filters, and catalyst towers (SCR: Selective Catalytic Reduction), and air recycling facilities in waste storage tanks. However, it is being avoided because of the perception that it is an incinerator. To resolve these conflicts, the government installs and operates resident convenience facilities to compensate residents near resource recovery facilities, provides green space and improves the environment, and supports heating expenses in accordance with the 「Waste Treatment Facility Support Act」. The purpose of this study is to derive implications through the analysis of domestic and overseas case studies for resident convenience facilities and environment improvement for the promotion of local communities in resource recovery facilities and use them as basic data for community promotion and environmental improvement when installing resource recovery facilities in the future.

Characteristics of Cell Strings According to Wire Soldering Conditions for High Power Solar Module (고출력 태양광 모듈을 위한 와이어 솔더링 조건에 따른 셀 스트링 특성)

  • See Hee Hwang;Seung Ah Ur;Yo Han Noh;Jae Hyeong Lee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.37 no.6
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    • pp.614-618
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    • 2024
  • MBB (multi-busbar) technology is a module technology to achieve high power, and the use of a number of thin circular metal wires increases light-receiving capacity and reduces resistance. In the process of interconnection using a wire, the stress of the cell increases depending on the degree of coupling between the wire and the cell and the degree of damage caused by heat, or the mobility of current decreases due to poor bonding. The degree of such loss is affected by IR lamp, hot plate temperature and wire thickness. In addition, the values of contact resistance were compared and analyzed to analyze the cause of the decrease in electrical characteristics. In this study, process condition optimization was carried out through peeling test, SEM analysis, EL test, and pre/post bonding efficiency characteristic analysis of the bonded cell according to process conditions, compared the contact resistance.