• Earthquakes and Structures
• /
• v.6 no.4
• /
• pp.351-373
• /
• 2014

This paper investigates the seismic response of lightweight acceleration-sensitive non-structural components (NSCs) mounted on irregular reinforced concrete (RC) primary structures (P-structures) using non-linear dynamic finite element (FE) analysis. The aim of this paper is to study the influence of NSC to P-structure vibration period ratio, peak ground acceleration, NSC to P-structure height ratio, and P-structure torsional behaviour on the seismic response of the NSCs. Representative constitutive models were used to simulate the behaviour of the RC P-structures. The NSCs were modelled as vertical cantilevers fixed at their bases with masses on the free ends and varying lengths so as to match the frequencies of the P-structures. Full dynamic interaction is considered between the NSCs and P-structures. A set of 21 natural and artificial earthquake records were used to evaluate the seismic response of the NSCs. The numerical results indicate that the behaviour of the NSCs is significantly influenced by the investigated parameters. Comparison between the FE results and Eurocode (EC8) predictions suggests that EC8 underestimates the response of NSCs mounted on the flexible sides of irregular RC P-structures when the fundamental periods and heights of the NSCs match those of the P-structures. The perceived cause of this discrepancy is that EC8 does not take into account the amplification in the dynamic response of NSCs induced by the torsional behaviour of RC P-structures.

• Journal of Ocean Engineering and Technology
• /
• v.30 no.6
• /
• pp.440-450
• /
• 2016

The capsizing and consequent sinking of a coastal car ferry was recently reported, with numerous human casualties. The primary cause was determined to be a sudden turn with improperly stowed and secured cargo. Part I of this study introduces how long term acceleration components are determined from seakeeping analyses. A carferry with a displacement of 1,633 tonf was selected as the target vessel. Sea data that included the significant wave heights and periods were collected at four observation buoys, some of which were far away from two main voyage routes: Incheon-Jeju and Pusan-Jeju. Frequency response analyses were performed to obtain the linearized radiation force coefficients, hydrostatic stiffnesses, and wave excitation forces. Time response analyses were sequentially performed to produce the motion-induced acceleration processes. The probabilistic distributions of the acceleration components were determined using a peak and valley counting method. Long term extreme acceleration components were proposed as a final result.

• Journal of the Korean Dietetic Association
• /
• v.3 no.2
• /
• pp.123-140
• /
• 1997

The purpose of this study were to assess main management components that can lead to successful university foodservice operations. Specifically, it was intended to develop the tool which assesses the service quality, management, to assess the difference between customer importance from and perceptions of service quality, to compare management perceptions of customer importances with actual service delivery, and to identify internal problems which affect service quality with the use of gap model. Three types of questionnaires were developed and implemented for customers, foodservice personals and foodservice manager. Assessment tools were developed based on the literature review, SERVQUAL, GAP model, and the pilot study. Through the validity and reliability test, the questionnaires were revised. Questionnaires were distributed to 900 university students, 207 foodservice personnels, and 54 foodservice manager respectively. 831 university students, 177 foodservice personnels, and 48 foodservice manager were responded with a response rate of 92.3%, 85.5%, and 88.8% respectively. Statistical data analysis was completed using the SPSS programs for descriptive analysis, ANOVA. and SNK test. The results of this study can be summarized as follows : 1. In quality service management components, 31 quality service attributes were categorized and named into primary quality, secondary quality, hygiene, empathy, tangibles, reliability, responsiveness, and price by the factor analysis. 2. Importance mean score of customers was 4.02 out of 5, but perception mean score of customers was 2.55. So there was a relative big gap(1.47) between importance and perception scores, especially in three dimensions of responsiveness, primary quality, and hygiene. 3. It showed that customers' mean scores of perceived service quality by dimensions were the following order : price > reliability > secondary quality > hygiene > tangibles > primary quality > responsiveness > empathy. And the perception mean score of rented(2.59) or contracted(2.58) management was significantly higher than that of self-operated(2.48). 4. Customers' importances mean score which internal customers recognize was 4.23 out of 5, but service delivery mean score was 3.85. So there was a little gap(0.39) between management perceptions of customer importances and actual service delivery. 5. In gap model, SERVQUAL score showed -1.47, Gap 1 positive 0.15, gap 2 negative 0.61, and gap 3 was positive 0.19. 6. The internal problems were as follows : (1) The managers of University foodservice perceived well enough the customers' expectation value but their management competency was lacked in terms of responding customer needs, (2) The foodservice staff perceived service performance more highly than service quality specifications.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2010.06a
• /
• pp.30-30
• /
• 2010

The Angle Ring and Cap which is called pressboard are settled at primary and secondary coil winding of 154 kV transformer that can reduce effectively distance of insulation. As it has not manufactured pressboard of Angle Ring and Cap for high voltage grade, insulation components industry especially high voltage transformer has not participate in a competition with worldwide yet. That's why is difficult to make an specialized shape of insulation components of high voltage grade. At first, it is very important to make an utility of deformation manufacturing for high voltage transformer insulation components by itself. Therefore it has finally completed to make an deformation manufacturing utility using an special analysis tools. In this paper, developed insulation components was investigates in tensile strength is introduced.

• Educational Technology International
• /
• v.24 no.2
• /
• pp.115-141
• /
• 2023

The aim of this research is to understand the perceptions of primary and secondary teachers regarding educational resource sharing systems(ERS) by using a qualitative approach. This study conducted Focus Group Interview(FGI) with 20 primary and secondary school teachers. Interview data were analyzed through inductive content analysis method. The results are as follows. First, teachers placed significant emphasis on high-quality, convenient functions, and reward system for sharing resources. Specifically, teachers identified the necessity for a diverse array of materials, systematic categorization of these resources, and the provision of monetary compensation as essential components. Second, the study participants advocated strategies for revitalizing ERS including enhancing accessibility, constructing user-friendly features, increasing awareness, and establishing a reward system to incentivize the resource sharing. In particular, teachers proposed strategies such as developing mobile-based services and AIdriven data recommendation system. These results provide actionable insights for stakeholders engaged in the design, implementation, and evaluation of resource sharing platforms.

• Journal of the Korean Ceramic Society
• /
• v.46 no.1
• /
• pp.74-80
• /
• 2009

Electrospinning process is the useful and unique method to produce nanofibers from metal precursor and polymer solution by controlled viscosity. In this study, the NiZn ferrite nanofibers were prepared by electrospinning with a aqueous metal salts/polymer solution that contained polyvinyl pyrrolidone and Fe (III) chloride, Ni (II) acetate tetrahydrate and zinc acetate dihydrate in N,N-dimethylformamide. The applied electric field and spurting rate for spinning conditions were 10 kV, 2 ml/h, respectively. The obtained fibers were treated at $250^{\circ}C$ for 1 h to remove the polymer. Finally, the NiZn ferrite fibers were calcined at $600^{\circ}C$ for 3 h and annealed at $900{\sim}1200^{\circ}C$ in air. By tuning the viscosity of batch solution before electrospinning, we were able to control the microstructure of NiZn ferrite fiber in the range of $150{\sim}500\;nm$ at 770 cP. The primary particle size in $600^{\circ}C$ calcined ferrite fiber was about 10 nm. The properties of those NiZn ferrite fibers were determined from X-ray diffraction analysis, electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, thermal analysis, and magnetic measurement.

• Nuclear Engineering and Technology
• /
• v.54 no.2
• /
• pp.507-513
• /
• 2022

When X-ray energy above 8 MV is used, photoneutrons are generated by the photonuclear reaction, which activates the components of linear accelerator (linac). Safely managing the radioactive material, when disposing linac or replacing components, is difficult, as the standards for the radioactive material management are not clear in Korea. We surveyed the management status of radioactive components occurred from medical linacs in Korea. And we also measured the activation of each part of the discarded Elekta linac using a survey meter and portable High Purity Germanium (HPGe) detector. We found that most medical institutions did not perform radiation measurements when disposing of radioactive components. The radioactive material was either stored within the institution or collected by the manufacturer. The surface dose rate measurements showed that the parts with high surface dose rates were target, primary collimator, and multileaf collimator (MLC). ⁶⁰Co nuclide was detected in most parts, whereas for the target, ⁶⁰Co and ¹⁸⁴Re nuclides were detected. Results suggest that most institutions in Korea did not have the regulations for disposing radioactive waste from linac or the management procedures and standards were unclear. Further studies are underway to evaluate short-lived radionuclides and to lay the foundation for radioactive waste management from medical linacs.

• Education of Primary School Mathematics
• /
• v.26 no.4
• /
• pp.237-255
• /
• 2023

At a time when the textbooks publishing system is changing from government-administered to certified, it is necessary to analyze textbooks published in both systems. This study analyzed one government textbook and three certified textbooks on quadrilaterals based on the instructional components that must be taught in the area of 2-D shapes. As a result of the analysis, it was found that concept exploration was implemented appropriately, but classification activities were not presented in some lessons. In Defining Concepts, the definition of the concept was presented appropriately, but there were differences depending on the textbooks. In addition, it was found that there was little activity in talking about the components of shapes or shapes. In applying concepts, more diverse activities were presented in certified textbooks than in government textbooks. Knowing relationships are rarely presented in textbooks due to its influence on the curriculum. Based on the results of this analysis of quadrilaterals, this study provides textbook writers with implications on what to further consider is dealing with quadrilaterals.

• Journal of the Korean Society of Industry Convergence
• /
• v.2 no.1
• /
• pp.77-83
• /
• 1999

Grown in the secondary broth of production media, the strain Streptomyces albulus has increased more the production of its metabolite ${\varepsilon}$-poly-L-lysine, one of poly(amino acid)s used as disinfecting food additives, than the strain in the primary culture of growth nutrients. Having the strain removed, the large concentrate obtained by ultrafiltrating the secondary culture broth. The concentrated production broth exchanged into followed by detecting in UV flowcell at 220nm the peptide bond of the components eluting the adsorbed proteins and polylysine with NaCl salt of gradient concentration, and has separated into five components. Among them the component in the fourth peak fraction has proved to be the pure ${\varepsilon}$-poly-L-lysine after the portion being hydrolyzed the fraction with HCl into amino acid followed by being the composing amino acid analysis.

• Proceedings of the KSR Conference
• /
• 2003.10c
• /
• pp.3-7
• /
• 2003

The dynamics of the pantograph motion and contact forces of the high-speed railway are investigated through signals. acquired during a test run. The signals are obtained from accelerometers, load cells, and strain gauges attached to various positions of the pantograph, and they are processed in time-and frequency-domains to evaluate the dynamic characteristics and load forces. The natural frequencies of the pantograph is found to be 8.5Hz. There also are frequency components varying linearly with the train speed. The signal frequency components above 40Hz are attenuated as they pass through the primary and secondary suspensions.