• Journal of the Optical Society of Korea
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• v.18 no.4
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• pp.382-387
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• 2014

An all-reflective, simple noncollinear second harmonic (SH) autocorrelator is described for monitoring the shot-to-shot behavior of ultrashort high-power laser pulses. Two mirrors are used for the dispersion-free splitting of a pulse into two halves. One of the mirrors is able to adjust the delay time and angle between two halves of the laser pulse in a nonlinear crystal. We present the possibility of real-time measurement of the pulse duration, peak intensity (or energy), and the pointing jitters of a laser pulse, by analyzing the spatial profile of the SH autocorrelation signal measured by a CCD camera. The measurement of the shot-to-shot variation of those parameters will be important for the detailed characterization of laser accelerated electrons or protons.

• ETRI Journal
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• v.44 no.6
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• pp.915-924
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• 2022

In this paper, we present a two-stage scalable channel estimator (TSCE), a deep learning (DL)-based scalable, and robust channel estimator for wireless cellular networks, which is made up of two DL networks to efficiently support different resource allocation sizes and reference signal configurations. Both networks use the transformer, one of cutting-edge neural network architecture, as a backbone for accurate estimation. For computation-efficient global feature extractions, we propose using window and window averaging-based self-attentions. Our results show that TSCE learns wireless propagation channels correctly and outperforms both traditional estimators and baseline DL-based estimators. Additionally, scalability and robustness evaluations are performed, revealing that TSCE is more robust in various environments than the baseline DL-based estimators.

• International Journal of High-Rise Buildings
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• v.12 no.3
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• pp.209-214
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• 2023

Seismic performance-based design methods are widely used in the field of engineering. This paper introduces the current status of seismic performance-based design methods for high-rise buildings in China, and summarizes latest advancements in seismic performance-based design methods for high-rise buildings in China, with a focus on the design methods based on predetermined yield mode and the design methods based on member ductility requirements. Finally, the development direction of seismic performance-based design method for high-rise buildings is prospected.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• v.2
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• pp.307-310
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• 2006

In this paper, we design a prototype service in Telematics environment for providing safety warning notification at crooked roads efficiently using wireless sensor network. Through this study, we 1) analyze several requirements to be satisfied in the services, 2) design and implement the service architecture based on the requirements.

• Perspectives in Nursing Science
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• v.8 no.2
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• pp.129-138
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• 2011

Purpose: The purpose of this study was to identify the current status of evidence-based research, education, and practice, and to suggest a directions for the future development of evidence-based nursing. Methods: To examine the current status of evidence-based nursing research, experimental research among studies published in the Journal of Korean Academy of Nursing from 2008 to 2010 were analyzed. We suggested a direction for the future development of evidence-based research based on the analysis and literature reviews. We also suggested a direction for the future development of evidence-based education and practice based on literature reviews. Results: The results showed that designs and methods of studies were insufficient to use evidences derived from the studies in terms of evidence-based research, and experimental studies consistent with themes were found to be deficient. In the future, the methods and rationale for the design of experimental studies need to be clearer In addition, a test for intervention effects through repetitive studies and a connection between the intervention effects and a protocol for clinical practice will be required. In terms of evidence-based education, curriculum revision and development of teaching methods including contents related to evidence-based practice and research methodology in undergraduate and graduate programs will be required. Evidence-based practice in Korea was less actively done than with that of foreign countries. Some large hospitals have recently attempted systemic activities to promote evidence-based nursing practice in clinical settings. To activate evidence-based practice, the perception of nurses for evidence-based practice needs to be changed and support for education and administration of the program is required. Also, evidence-based practice guidelines, protocols, and assessment tools need to be developed. Conclusion: Evidence-based nursing in Korea is in the process of evolving. To realize evidence-based nursing, we need to develop nursing science based on evidences of closer communication and cooperation in terms of nursing research, education, and practice.

• Tribology and Lubricants
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• v.31 no.5
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• pp.195-204
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• 2015

Several researches are focused on improving the value of fine chemicals based on biomass resources due to environmental and other concerns associated with the use of petroleum-based products. Therefore, the synthesis and application of estolides derived from plant-based waste oil materials and their application as lubricants and as processing oil for butyl rubber products have been studied. Four kinds of estolide were prepared with conversions of 71~92% over 24h using various vegetable oils, as determined by size exclusion chromatography (SEC) and nuclear magnetic resonance (NMR) spectroscopy. FT-IR spectroscopy determines the esterification of estolides using 2-ethylhexyl alcohol. The estolides have iodine values of 35~90, α-ester/α-acid ratios of 0.45~0.55, and total acid number of 114~134 mg KOH g^–1. Four ball wear tests show that the wear scar diameters (WSDs) of estolides as base oil significantly decreased to 0.328~0.494 mm, compared to WSDs of 0.735 and 0.810 mm of WSD for 150N and Yubase 6, respectively, as general base oil. Thus, the estolides have better wear resistance and satisfying design objectives for the engineering of a variety of lubricant base oils.

• Nuclear Engineering and Technology
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• v.47 no.3
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• pp.315-322
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• 2015

The research carried out on thorium-based fuels indicates that these fuels can be considered as economic alternatives with improved physical properties and proliferation resistance issues. In the current study, neutronic assessment of $UO_2$ in comparison with two $(Th-^{233}U)O_2$, and $(Th-^{235}U)O_2$ thorium-based fuel loads in a heavy water research reactor has been proposed. The obtained computational data showed both thorium-based fuels caused less negative temperature reactivity coefficients for the modeled research reactor in comparison with $UO_2$ fuel loading. By contrast, $^{235}U$-containing thorium-based fuel and $^{235}U$-containing thorium-based fuel loadings in the thermal core did not drastically reduce the effective delayed neutron fractions and delayed neutron fractions compared to $UO_2$ fuel. A provided higher conversion factor and lower transuranic production in the research core fed by the thorium-based fuels make the fuel favorable in achieving higher cycle length and less dangerous and costly nuclear disposals.

• Korean Journal of Childcare and Education
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• v.14 no.6
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• pp.219-239
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• 2018

Objective: This study aims to analyze the research trend of domestic child care education, and to seek directions for future research related to child care education based on analysis results. Methods: A total of 91 theses were selected in journals released in Korea from January 2006 to August 2018. The analysis standards for the research trend were established as research period, theme, target and method. Results: First, the amount of research on child care education has gradually increased since 2006. Second, action research for improvement was the most common research theme for child care education, while activities utilizing fairy tales and picture books were the most frequently used education activities. Third, research that targeted five-year-olds accounted for the largest part of research. Fourth, when it came to research type, most research was based on quantitative research. Conclusion/Implications: Based on the analysis results above, the direction for the development of future child care education and relevant research was discussed.

• ETRI Journal
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• v.27 no.5
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• pp.497-503
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• 2005

In this paper, we present a performance analysis for an MPEG-4 video codec based on the on-chip network communication architecture. The existing on-chip buses of system-on-a-chip (SoC) have some limitation on data traffic bandwidth since a large number of silicon IPs share the bus. An on-chip network is introduced to solve the problem of on-chip buses, in which the concept of a computer network is applied to the communication architecture of SoC. We compared the performance of the MPEG-4 video codec based on the on-chip network and Advanced Micro-controller Bus Architecture (AMBA) on-chip bus. Experimental results show that the performance of the MPEG-4 video codec based on the on-chip network is improved over 50% compared to the design based on a multi-layer AMBA bus.

• Journal of the Optical Society of Korea
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• v.11 no.3
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• pp.124-129
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• 2007

For the first time we compare two kinds of optical frequency combs, one of which is based on a Ti:sapphire femtosecond laser and the other is based on a mode-locked erbium-doped fiber laser. The comparison is performed by measuring an optical frequency standard with these two combs simultaneously. The two frequency measurements agree within 1.8 Hz ($3.8{\times}10^{-15}$) with the uncertainty of 17.2 Hz ($3.6{\times}10^{-14}$), from which it can be concluded that the Ti:sapphire-based frequency comb and the fiber-based frequency comb have no systematic discrepancy at this level of uncertainty.