• International Journal of Contents
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• v.5 no.3
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• pp.71-78
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• 2009

Recently, interest has heightened over 'critical infrastructures' and their reliability in the face of potential terrorist attack. Assault on any of the critical infrastructures as transportation, power, water, telecommunications, and financial services, entails great consequences for their users as well as the other interdependent critical infrastructures. How to protect our vital critical infrastructures is the key question in this paper. The purpose of this article is to suggest the implications for crisis and emergency management to protect the critical infrastructures in our society. For achieving the purpose, we examined the concept of comprehensive security, national crisis, and critical infrastructure and, using the holistic approach, we examined the comprehensive emergency management for suggesting the implications for establishing the critical infrastructure protection system; building up the high reliability organization, organizing and partnering, assessing the risk, preparing first responders, working with private owners of critical infrastructures, working with communities, improving the administrative capacity.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.1
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• pp.183-195
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• 2014

Multicasting is an efficient way of group communications because one sender can transmit data to multiple receivers with only one transmission. Furthermore, multicasting is considered an appropriate transmission method for multimedia services. Multimedia applications are expected to become more prevalent over mobile ad-hoc networks in the near future. Therefore, achieving reliability in multimedia communications is an important task. In this paper, we propose a leader-based reliable multicast medium access control layer protocol for multimedia applications to enhance video quality. We present a Markov chain model and numerical formulation of our proposed system.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.555-560
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• 2008

Korean Train Express (KTX) has been commercially operating and achieving elevation on transport capacity since 2004. And HSR-350x was developed and succeeded in testing of running over 350km/h. The new high-speed train development project, HEMU-400x project, has started since last year. To develop the train system, it is important how we progress the configuration of the system, design, manufacturing and test verification. The authors devised the performance estimate and verification process of the HEMU-400x and the project is performed following the developed processes.

• Journal of Magnetics
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• v.6 no.2
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• pp.73-76
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• 2001

A double rectangular spiral type inductor has been fabricated by using FeTaN films. The inductor is composed of internal coils sandwiched by magnetic layers. Characteristics of inductor performance are investigated with an emphasis on planarization of magnetic films. In the absence of the planarization process, the grating topology of the upper magnetic films over the coil arrays degrades the soft magnetic properties and the inductor performance. It also induces a longitudinal magnetic anisotropy with the easy axis aligned to the magnetic flux direction. This alignment prevents the upper magnetic films from contributing to the total induction. Glass bonding is a viable method for achieving a completely planar inductor structure. The planar inductor with glass bonding shows excellent performance: inductance of 1.1 $\mu H$, Q factor of 7 (at 5 MHz), and the current capability up to 100 mA.

• East Asian mathematical journal
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• v.38 no.4
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• pp.517-532
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• 2022

This study looked at how content reviews with mathematical games in class would influence the mathematical disposition of middle school students. In doing so, three games adapted from prior research were used as a supplementary instruction after school hours over three months. The mathematical topics of the games involved concepts of probability and trigonometry at the middle school level. The results of the pre- and post-survey on mathematical disposition indicate that incorporating mathematical games appeared to have some positive impacts on whether students might be more eager to learn mathematics and actually put more effort in learning materials.

• East Asian mathematical journal
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• v.40 no.2
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• pp.231-265
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• 2024

Achieving something in learning is a very important task. Due to its significance, extensive research has been conducted over a long period to determine what factors influence learning. In the field of mathematics, such research has been continuously carried out, and as a result, it has been revealed that cognitive, affective, and socio-environmental factors influence mathematics learning. However, most of these studies were based on one or two variables, and thus, they did not comprehensively examine the factors affecting mathematics learning. Therefore, this study aims to synthesize the existing research to comprehensively derive the factors influencing mathematics learning.

• Progress in Superconductivity and Cryogenics
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• v.26 no.1
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• pp.1-4
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• 2024

This study explores the use of a bulk type high-temperature superconductors (HTS) as trapped field magnets in synchronous motors. A HTS bulk is examined for its ability to generate powerful magnetic fields over a permanent magnet and to eliminate the need for a direct power supply connection compared to a tape form of HTS. A 150 kW interior-mounted bulk-type superconducting synchronous motor is designed and analyzed. The A-H formulation is used to numerical analysis. The results show superior electrical performance and weight reduction when comparing the designed model with the conventional permanent magnet synchronous motor of the same topology. This study presents HTS bulk synchronous motor's overall design process and highlights its potential in achieving relatively high power density than conventional permanent magnet synchronous motor.

• Nuclear Engineering and Technology
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• v.56 no.7
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• pp.2775-2780
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• 2024

Special methods for cleaning surfaces of stainless steel with a coating simulating radioactive contamination have been developed and studied. The removal of simulated surface contamination was performed using lasers in the micron spectral range with pulse durations of 8 ns and 270 fs. Optimal cleaning modes were determined for gas and liquid environments, achieving surface cleaning coefficient of over 90% in a single pass. A correlation between the degree of cleaning in liquids and the viscosity of the environment was discovered.

• Current Optics and Photonics
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• v.4 no.3
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• pp.161-173
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• 2020

Colloidal quantum dots (QDs) have gained tremendous attention as a key material for highly advanced display technologies. The performance of QD light-emitting diodes (QLEDs) has improved significantly over the past two decades, owing to notable progress in both material development and device engineering. The brightness of QLEDs has improved by more than three orders of magnitude from that of early-stage devices, and has attained a value in the range of traditional inorganic LEDs. The emergence of high-luminance (HL) QLEDs has induced fresh demands to incorporate the unique features of QDs into a wide range of display applications, beyond indoor and mobile displays. Therefore it is necessary to assess the present status and prospects of HL-QLEDs, to expand the application domain of QD-based light sources. As part of this study, we review recent advances in HL-QLEDs. In particular, based on reports of brightness exceeding 10⁵ cd/㎡, we have summarized the major approaches toward achieving high brightness in QLEDs, in terms of material development and device engineering. Furthermore, we briefly introduce the recent progress achieved toward QD laser diodes, being the next step in the development of HL-QLEDs. This review provides general guidelines for achieving HL-QLEDs, and reveals the high potential of QDs as a universal material solution that can enable realization of a wide range of display applications.

• Journal of Korean Society of Rural Planning
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• v.21 no.4
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• pp.85-94
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• 2015

The purpose of this study is to investigate how the hollowization in rural villages which causes marginal villages appears in Korean rural villages and whether the hollowization has relation with decrease and aging of population or not. For achieving the research objective, survey was carried out focused on Geumsan-gun. As a result, it confirmed that rural out-migration and rural decline especially in 'people', 'land(economic situation)' and 'community' have being progressed. Also variance analysis and regression analysis were executed with using the number of population and the ratio of people over 65 as dependent variables and using each survey contents(variables) as independent variables. The results of analysis showed that the ratio of people over 65(+), the income level per household(-), the rate of fallow lands(+), the number of empty houses(+), programs for urban-rural interchange(+), and the implementing public projects(+), etc. have a relation with the number of population(-) and the number of population(-), the income level per household(-), the rate of fallow lands(+), the number of empty houses(+), activities of communities(+), and the implementing public projects(+), etc. have a relation with the ratio of people over 65(+) (+: increase, -: decrease). So the hollowization in people', 'land(economic situation)' and 'community' has direct relation with decrease and aging of population in rural areas.