• Journal of the Computational Structural Engineering Institute of Korea
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• v.26 no.2
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• pp.99-112
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• 2013

This paper presents a subspace system identification for estimating the stiffness matrix and flexural rigidities of a shear building. System matrices are estimated by LQ decomposition and singular value decomposition from an input-output Hankel matrix. The estimated system matrices are converted into a real coordinate through similarity transformation, and the stiffness matrix is estimated from the system matrices. The accuracy and the stability of an estimated stiffness matrix depend on the size of the associated Hankel matrix. The estimation error curve of the stiffness matrix is obtained with respect to the size of a Hankel matrix using a prior finite element model of a shear building. The sizes of the Hankel matrix, which are consistent with a target accuracy level, are chosen through this curve. Among these candidate sizes of the Hankel matrix, more proper one can be determined considering the computational cost of subspace identification. The stiffness matrix and flexural rigidities are estimated using the Hankel matrix with the candidate sizes. The validity of the proposed method is demonstrated through the numerical example of a five-story shear building model with and without damage.

• Journal of KIISE:Computing Practices and Letters
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• v.10 no.5
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• pp.406-418
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• 2004

Last days, various kinds of applications and system were individually introduced into specific groups or enterprises by different objective without considering interoperability among those. However, the environment for data processing is changing rapidly in these days. And now the necessity is growing to integrate and couple applications and system in the process dimension for more flexible and quicker data processing on these application programs and system. When integrating these application programs or system, an integration based on XML is recommended as it is one of good methods which will the additional cost and satisfy the requirements of the integration. This is because the XML is not only device-independent data type which can be used any platform, but also it uses XSLT, the document conversion standard established by W3C, which allows easy data conversion from one to another type on occasion of demands. This paper studies a design and implementation of system to convert XML structure. This system shows the structure of source- side providing data and destination-side processing data with using XML schema that defines structural information of a XML document. And this system defines the structure relationship of desired form as mapping structural information and data. This system creates the XSLT document that defines conversion rule between two structures based information which is defined. The XSLT document which is created as described above will convert data to be appropriate to the structure of the destination- side. By implementing this system, it is able to apply a document into various kinds of structure without considering specific system or platform and it is able to construct XSLT document to which meaning of desired form can be given. This paper aims to offer a process conversion between documents and to improve interoperability and scalability, so that we can contribute to build XML document processing environment

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.261-273
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• 2011

Recently, the demands for steel frame are increasing because of the trend and due to the demand for bigger and higher buildings. In the analysis of typical steel frame, connections are based on the idealized fixed or pinned connection. A fixed connection assumes that the relative angle of each member before deformation is the same after the transformation. Therefore, the stiffener reinforces the connection to sufficient rigidity and stability of the panel zone. In the economical aspect, however, the necessity of connection that the stiffener reinforcement has omitted is increasing due to the excessive production as well as labor costs of connection. In contrast, pinned connection is assumed that bending moments between the beams and columns do not transfer to each member. This is easy to make in the plant and the construction is simple. However, the structural efficiency is reduced in pinned connection because connection cannot transfer moments. The introduction of this semirigid process can decide efficient cross-sectional dimensions that promote ease in the course of structural erection, as performed by members in the field-a call for safety in the entire frame. Therefore, foreign countries exert efforts to study the practical behavior and the results are applied to criterion. This paper analyzes the semirigid connection of domestic steel by design specifications of AISC/LRFD and make data bank that pertain to each steel. After wards, the results are compared to those of idealized connection; at the same time, this paper presents a design method that matches economic efficiency, end-fixity, and rotational stiffness.

• Journal of the Mineralogical Society of Korea
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• v.25 no.4
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• pp.283-293
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• 2012

In order to have better insights into the chemical differentiation of Earth from its magma ocean phase to the current stratified structure, detailed information of crystallization kinetics of silicate melts consisting of the magma ocean is essential. The structural transitions in oxide glasses and melts upon crystallization provide improved prospects for a systematic and quantitative understanding of the crystallization processes. Here, we report the $^{27}Al$ 3QMAS NMR spectra for sol-gel synthesized $Al_2O_3$ glass with varying temperature and annealing time. The NMR spectra for the amorphous $Al_2O_3$ show well-resolved Al coordination environments, characterized with mostly $^{[4,5]}Al$ and a minor fraction of $^{[6]}Al$. The fraction of $^{[5]}Al$ in the alumina phase decreases with increasing annealing time at constant temperature. The NMR results of $Al_2O_3$ phases also imply that multiple processes (e.g., crystallization and/or changes in structural disorder within glasses) could involve upon its phase transition. The current results and method can be useful to understand crystallization kinetics of diverse natural and multi-component silicate glasses and melts. The potential result may yield atomic-level understanding of Earth's chemical evolution and differentiation from the magma ocean.

• Journal of the Korean Society for information Management
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• v.32 no.2
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• pp.131-152
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• 2015

This study described the results of converting RDB to RDF ontology by each of R2RML method and Non-R2RML method. This study measured the size of the converted data, the conversion time per each tuple, and the response speed to queries. The STNet, a structured terminology dictionary based on RDB, was served as a test bed for converting to RDF ontology. As a result of the converted data size, Non-R2RML method appeared to be superior to R2RML method on the number of converted triples, including its expressive diversity. For the conversion time per each tuple, Non-R2RML was a little bit more faster than R2RML, but, for the response speed to queries, both methods showed similar response speed and stable performance since more than 300 numbers of queries. On comprehensive examination it is evaluated that Non-R2RML is the more appropriate to convert the dynamic RDB system, such as the STNet in which new data are steadily accumulated, data transformation very often occurred, and relationships between data continuously changed.

• International Journal of Computer Science & Network Security
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• v.22 no.7
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• pp.259-267
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• 2022

With the rapid development and introduction of digital technologies, both everyday human life and technological processes of any production are changing, which stimulates the transformation of the economy and education. Digital technologies are not only a tool, but also a living environment of modern human, which opens up new opportunities: learning at any convenient time, continuing education, the ability to form individual educational learning trajectories and more. However, the digital environment requires teachers to take a modern approach to the organization of the educational process, the formation of new skills and abilities to work in the digital educational environment. As a result of the study, it was found that the system of vocational education should provide training for masters of industrial training who have a high level of digital competence. The purpose of the article is to single out, theoretically substantiate and determine the level of formation of structural components of digital competence of future masters of agricultural training. The structure of digital competence of agricultural master was analyzed on the basis of domestic and foreign scientists researches. Systematized research results indicate that digital competence consists of four components: motivational-value (combination of internal and external motives for the use of digital technologies in future professional activities), cognitive (a set of theoretical knowledge, skills and abilities of future master of industrial training to effectively build educational process with the use of digital technologies), activity-professional (expansion and deepening of knowledge, skills, necessary skills for effective implementation of digital technologies in the educational process) and evaluative-reflexive (ability to analyze and self-analyze own activities and its results taking into account professional characteristics, self-realization in professional activities through the use of digital technologies). These components are comparable with the indicators that describe the knowledge, skills and abilities needed by the future master of industrial training to organize the modern educational process. A questionnaire was conducted to determine the levels of this competence formation, which allows us to conclude that it is necessary to increase the level of formation of all components of digital competence of future masters of industrial training in agriculture. The results of the study can be used as a basis for the development of disciplines that form the special competencies of masters of industrial training in agriculture and programs of advanced training of teachers.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.30-39
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• 2023

Large dams, which are critical infrastructures for disaster prevention, are exposed to various risks such as aging, floods, and earthquakes. Better dam safety inspection and diagnosis using digital transformation technologies are needed. Traditional visual inspection methods by human inspectors have several limitations, including many inaccessible areas, danger of working at heights, and know-how based subjective inspections. In this study, drone photogrammetry was performed on two large dams to evaluate the applicability of digital data-based dam safety inspection and propose a data management methodology for continuous use. High-quality 3D digital models with GSD (ground sampling distance) within 2.5 cm/pixel were generated by flat double grid missions and manual photography methods, despite reservoir water surface and electromagnetic interferences, and severe altitude differences ranging from 42 m to 99.9 m of dam heights. Geometry profiles of the as-built conditions were easily extracted from the generated 3D mesh models, orthomosaic images, and digital surface models. The effectiveness of monitoring dam deformation by photogrammetry was confirmed. Cracks and deterioration of dam concrete structures, such as spillways and intake towers, were detected and visualized efficiently using the digital 3D models. This can be used for safe inspection of inaccessible areas and avoiding risky tasks at heights. Furthermore, a methodology for mapping the inspection result onto the 3D digital model and structuring a relational database for managing deterioration information history was proposed. As a result of measuring the labor and time required for safety inspection at the SYG Dam spillway, the drone photogrammetry method was found to have a 48% productivity improvement effect compared to the conventional manpower visual inspection method. The drone photogrammetry-based dam safety inspection is considered very effective in improving work productivity and data reliability.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.7
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• pp.445-453
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• 2012

An investigation for removal of 1-indanone (1-ID), which were commonly produced from the biological and/or chemical treatment and natural weathering of the PAHs-contaminated soils, via oxidative transformation mediated by birnessite in the presence of various phenolic mediators is described. This study also examines the potential effect of the natural occurring substance humic acid (HA) on the oxidative transformation. The experiment was carried out in aqueous phase as a batch test (10 mg/L 1-ID, 0.3 mM phenolic mediators, $1.0g/L\;{\delta}-MnO_2$, at pH 5). All of the 11 tested phenoilic mediators belong to the group of natural occurring phenols and are widely used as model constituents of humic substances. From the results of HPLC analysis, it is demonstrated that 1-ID was not reactive to birnessite itself, but it can be effectively removed in birnessite-mediated cross coupling reactions in the presence of the phenolic mediators. The percent removals of 1-ID after 2 day incubation were ranged from 9.2 to 71.2% depending on the phenolic mediators applied. The initial rate constant ($K_{int}$, $hr^{-1}$) values for the 1-ID removals obtained from the pseudo-first-order kinetic plots also widely ranged from 0.18 to 15.0. Results of the correlative analysis between the removal efficiencies and structural characteristics of phenolic mediators indicate that the transformation of the 1-ID was considerably enhanced by the addition of electron-donating substituents (e.g., -OH, $-OCH_3$) at the benzne ring, and much less enhanced by the addition of electron-withdrawing substituents (e.g., -COOH, -CHO). The presence of HA showed that removal efficiencies of 1-ID in the birnessite-phenolic mediator systems decreased with increasing HA concentrations. However at low concentration of HA (< 2 mg/L), it caused some enhancement in the removals of 1-ID as compared to the control.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.629-635
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• 2001

To improve the ductility of $A1_3Hf$ intermetallics, which are the potential high temperature structural materials, the mechanical alloying behavior. the effect of Cu addition on the $Ll_2$ phase formation and the behavior of vacuum hot-pressed consolidation were investigated. During the mechanical alloying by SPEX mill, the $Ll_2 A1_3Hf$ intermetallics with the grain size of 7~8nm was formed after 6 hours of milling in Al-25at.%Hf system. The $Ll_2$ Phase of Al_3Hf$ intermetallics with the addition of 12.5at.%Cu, similar to that of the binary Al-25at.% Hf, was formed, but the milling time necessary for the formationof the $Ll_2$ phase was delayed form 6 hours to 10 hours. The lattice parameter of ternary $Ll_2(Al+Cu)_3Hf$ intermetallics decreased with the increase of Cu content. The onset temperature of $Ll_2$ to $D0_{23}$ phase in $Al_3Hf$ intermetallics was around 38$0^{\circ}C$, the temperature upon completion varied from 48$0^{\circ}C$ to 5$50^{\circ}C$ as the annealing time. The onset temperature of $Ll_2$ to $D0_{23}$ phase transformation in $(Al+ Cu)_3Hf$ intermetallics increased with the amount of Cu and the highest onset temperature of $700^{\circ}C$ was achieved by the Cu addition of 10at.%. The relative density increased from 89% to 90% with the Cu addition of 10at.% in $Al_3Hf$ intermetallics hot-pressed in vacuum under 750MPa at 40$0^{\circ}C$ for 3 hours. The relative density of 92.5% was achieved without the phase transformation and the grain growth as the consolidation temperature increased from 40$0^{\circ}C$ to 50$0^{\circ}C$ in $(Al+Cu)_3Hf$ intermetallics hot-pressed in vacuum under 750MPa for 3 hours.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.503-510
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• 2005

In this research, composite alumina was prepared to add the various promoters by sol-gel method and examined its thermal stability. After sintering at $1,200^{\circ}C$, the thermal stability resulted in following order, $Si{\fallingdotseq}La$ > Ti > $Ba{\fallingdotseq}Ce$ > Y > $Zr{\fallingdotseq}Mg$, in accordance with adding the promoters. Especially in case of silica-added alumina, a phase transformation temperature to ${\alpha}$-alumina increased about $150^{\circ}C$ and after sintering at $1,200^{\circ}C$, it showed to maintain in ${\gamma}$-form and ${\delta}$-form alumina phase. Also it showed an increase of surface area from $3m^2/g$ to $71m^2/g$ compared with pure ${\alpha}$-alumina. In the case of silicaadded alumina, the characterization change of this alumina particle resulted in a delay of phase transformation because Si-O-Al bond was increased when sintered at high temperature. In case of lanthanum-added alumina, there was a sintering delay phenomenon in inter-particles as $LaAlO_3$ structure existed. The existence of lanthanum structure was confirmed by XRD and XPS analysis. It appeared on the alumina surface as $La_2O_3$ structure when it was sintered under $1,000^{\circ}C$, as the perovskite structure of $LaAlO_3$ at above $1,000^{\circ}C$ and as the magneto-plumbite structure of $LaAl_{11}O_{18}$ at above $1,300^{\circ}C$.