• Nuclear Engineering and Technology
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• v.41 no.1
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• pp.1-10
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• 2009

The safe and reliable performance of fusion and fission plants depends on the choice of suitable materials and an assessment of long-term materials degradation. These materials are degraded by their exposure to extreme conditions; it is necessary, therefore, to address the issue of long-term damage evolution of materials under service exposure in advanced plants. The empirical approach to the study of structural materials and fuels is reaching its limit when used to define and extrapolate new materials, new environments, or new operating conditions due to a lack of knowledge of the basic principles and mechanisms present. Materials designed for future Gen IV systems require significant innovation for the new environments that the materials will be exposed to. Thus, it is a challenge to understand the materials more precisely and to go far beyond the current empirical design methodology. Breakthrough technology is being achieved with the incorporation in design codes of a fundamental understanding of the properties of materials. This paper discusses the multi-scale, multi-code computations and multi-dimensional modelling undertaken to understand the mechanical properties of these materials. Such an approach is envisaged to probe beyond currently possible approaches to become a predictive tool in estimating the mechanical properties and lifetimes of materials.

• Journal of Drive and Control
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• v.20 no.2
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• pp.24-30
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• 2023

This study aimed to analyze the fatigue of forklifts in industrial settings by assessing their stress levels during operation. Strain gauges were affixed to the dynamic components of the forklifts to gather real-time data and enhance the reliability of the analysis. Although monitoring structural loads in harsh testing environments can be challenging, the affixed strain gauges on the dynamic components can provide more precise results and improve the interpretation of data. By creating testing modes that simulate forklift usage environments and performing experiments with selected cargo and driving modes, a comparison of the damage severity of forklift parts under different driving conditions was done. These results can be utilized to forecast the lifespan of forklift parts under extreme driving conditions and assist in the design and optimization of new parts in the future.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.8-13
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• 2010

Satellite structure should be designed to accommodate and support safely the payload and equipments necessary for its own missions and to secure satellite and payloads from severe launch environments. The launch environments imposed on satellites are quasi-static accelerations, aerodynamic loads, acoustic loads and shock loads. Especially when optical payload is accommodated, satellite structure usually adopts the optical bench consisting of composite material not only to support and secure but also to guarantee good pointing stability against extreme thermal environments. This paper deals with optical bench and support structure which shall be designed to minimize the loads transferred to optical payloads from satellite.

• Journal of Species Research
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• v.9 no.1
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• pp.26-34
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• 2020

The phylum Bacteroidetes covers phenotypically diverse groups of Gram negative rods that do not form endospores, and currently includes 6 classes, 6 orders, 33 families and 380 genera. Members of Bacteroidetes can be aerobic and anaerobic heterotrophs, hydrogen utilizing chemolithotrophs, or methylotrophs. They can be isolated from diverse habitats including terrestrial and aquatic environments, environments with extreme physicochemical conditions, and animal and plant hosts. During a series of extensive surveys of prokaryotic species diversity in Korea, bacterial strains belonging to Bacteroidetes were isolated from various sources of aquatic and terrestrial environments. A total of 22 isolates were obtained, which represent 22 unrecorded species in Korea belonging to 14 genera of 6 families. Sixteen species among them were assigned to Flavobacteriaceae, two species were to Sphingobacteriaceae, and single species was to each of the families Bacteroidaceae, Balneolaceae, Chitinophagaceae and Cytophagaceae. At genus level, Chryseobacterium (5 species) and Flavobacterium (5 species) were the most abundant genera, and single species were obtained for the genera Bacteroides, Baloneola, Terrimonas, Dyadobacter, Aquimarina, Arenibacter, Gillisia, Gilvibacter, Salinimicrobium, Winogradskyella, Pedobacter and Sphingobacterium. The detailed descriptions of each unrecorded species are provided.

• Microbiology and Biotechnology Letters
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• v.47 no.3
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• pp.401-411
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• 2019

All Idiomarina species are isolated from saline environments; microorganisms in such extreme habitats develop metabolic adaptations and can produce compounds such as proteases with an industrial potential. ARDRA and 16S rRNA gene sequencing are established methods for performing phylogenetic analysis and taxonomic identification. However, 16S-23S ITS is more variable than the 16S rRNA gene within a genus, and is therefore, used as a marker to achieve a more precise identification. In this study, ten protease producing Idiomarina strains isolated from the Peruvian salterns were characterized using biochemical and molecular methods to determine their bacterial diversity and industrial potential. In addition, comparison between the length and nucleotide sequences of a 16S-23S ITS region allowed us to assess the inter and intraspecies variability. Based on the 16S rRNA gene, two species of Idiomarina were identified (I. zobellii and I. fontislapidosi). However, biochemical tests revealed that there were differences between the strains of the same species. Moreover, it was found that the ITS contains two tRNA genes, $tRNA^{Ile(GAT)}$ and $tRNA^{Ala(TGC)}$, which are separated by an ISR of a variable size between strains of I. zobellii. In one strain of I. zobellii (PM21), we found nonconserved nucleotides that were previously not reported in the $tRNA^{Ala}$ gene sequences of Idiomarina spp. Thus, based on the biochemical and molecular characteristics, we can conclude that protease producing Idiomarina strains have industrial potential; only two I. zobellii strains (PM48 and PM72) exhibited the same properties. The differences between the other strains could be explained by the presence of subspecies.

• Journal of the Korean Ceramic Society
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• v.49 no.4
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• pp.287-294
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• 2012

Ceramic Matrix Composites (CMCs) represent a class of non-brittle refractory materials for harsh and extreme environments in aerospace and other applications. The quasi-ductility of these structural materials depends on the quality of the interface between the matrix and the fiber surface. In this study, a manufacture route is described where in contrast to most other processes no additional fiber coating is used to adjust the fiber/matrix interfaces in order to obtain damage tolerance and fracture toughness. Adapted microstructures of uncoated carbon fiber preforms were developed to permit the rapid infiltration of molten alloys and the subsequent reaction with the carbon matrix. Furthermore, any direct reaction between the melt and fibers was minimized. Using pure silicon as the reactive melt, C/SiC composites were manufactured with an aim of employing the resulting composite for friction applications. This paper describes the formation of the microstructure inside the C/C preform and resulting C/C-SiC composite, in addition to the MAX phases.

• Journal of Marine Bioscience and Biotechnology
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• v.1 no.1
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• pp.1-8
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• 2006

Marine biotechnology encompasses biotechnology in areas such as marine microbiology, biomedical important marine natural products, organisms in extreme environments, and aquaculture. Marine biotechnology, today, poised to flourish more than ever from the confluences that are occurring in fundamental research in modern biology and other areas of science. Using research results from our laboratory and those from others, we will review the current advances of marine biotechnology in this lecture.

• Journal of the Korean Operations Research and Management Science Society
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• v.25 no.4
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• pp.111-122
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• 2000

This paper considers remanufacturing planning problems under deterministic environments. As increasing the environmental pressures in manufacturing, various methods for reducing wasted or postponing the time to be waste are considered. This paper considers remanufacturing planning problems on a single facility, where the wastes(or used products) are remanufactured to satisfy the given demand on the remanufactured products. The objective is to find the optimal remanufacturing and purchasing planning of the wastes which minimize total cost subject to satisfaction all the given demand on the remanufactured products. Two problems that the amount of wastes is a given constant or a decision variable are considered, respectively. For the problems, the extreme point solutions are characterized, and dynamic programming algorithms are developed with numerical examples.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.4
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• pp.181-185
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• 2011

Due to the increasing of nonlinear loads such as converters and inverters connected to the electric power distribution system, and extensive application of harmonic generation sources with power electronic devices, disturbance of the electric power system and its influences on industries have been continuously increasing. Thus, it is difficult to construct accurate load model for active and reactive power in environments with harmonics. In this research, we develop current harmonics estimation method based on Extreme Learning Machine (ELM) with fast learning procedure for residential loads. Using data sets acquired from various residential loads, the proposed method has been intensively tested. As the experimental results, we confirm that the proposed method makes it possible to effective estimate current harmonics for various input voltage.

• Journal of the Korean Society of Safety
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• v.33 no.3
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• pp.8-14
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• 2018

Ni-base superalloy has excellent resistance to extreme environments such as high temperatures and high stresses and are used as materials for large gas turbines. In this paper, the specimens were taken from the blade that were used for a long time, and their life span was studied by microstructure analysis and avoidance of cursing. The microstructural analysis of the specimens was carried out using a OM and SEM to observe the coarsening, carbides on gamma prime. Low-cycle fatigue tests were performed on new material and airfoil of long time-used blade. The test was conducted under various deformation conditions and temperature conditions of $760^{\circ}C$ and $870^{\circ}C$. The low cycle fatigue test was carried out using the Coffin-Manson equation and the fatigue life was predicted. After the test, crack path and fracture surface were analyzed using SEM.