• Current Applied Physics
• /
• v.18 no.11
• /
• pp.1426-1430
• /
• 2018

High magnetic field effects on the microstructure and magnetic properties of $BaFe_{12}O_{19}$ hexaferrites synthesized hydrothermal method have been investigated. The obtained results indicate that the lattice constant decreases gradually as the magnetic field strength increases, which may be attributed to the lattice distortion resulted from the high magnetic field. Polycrystalline $BaFe_{12}O_{19}$ samples prepared under magnetic field strength at zero and 5 T are single phase. It is found that application of external magnetic field during synthesis can induce orientated growth of the hexaferrite crystals along the easy magnetic axis. The magnetic properties can be effectively regulated by an application of high magnetic fields. It is observed that the $BaFe_{12}O_{19}$ prepared under a 5 T magnetic field exhibits a higher room-temperature saturation magnetization (66.3 emu/g) than that of the sample (43.6 emu/g) obtained without magnetic field. The results can be explained as the enhanced crystalline, improvement of $Fe^{3+}$ ions occupancy and the oriented growth induced by the external magnetic field. The growing orientation of particles gives rise to increased coercivity due to the enhancement in shape anisotropy. It is expected that an application of magnetic field during the formation of magnetic nanoparticles could be a promising technique to modify magnetic properties with excellent performance.

• Journal of the Korea Institute of Information Security & Cryptology
• /
• v.22 no.5
• /
• pp.1115-1122
• /
• 2012

VoIP service is steadily growing due to the spread of smartphones, enhanced network, and various VoIP applications. But, VoIP has many security vulnerabilities because it is based on IP network. This paper analyzes the important weight of VoIP security checklists for incident prevention and response using AHP. The results of AHP analysis showed that network security, incident response, and access control were the most important in technical, administrative, physical standpoint. This study proposes factor analysis of VoIP security checklist at first time. By doing this, it will be used helpfully when VoIP service providers establish their own security policies and inspect their VoIP environment according to their security policies.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.107-114
• /
• 2020

Technologies related scan-to-BIM for BIM-based reverse engineering techniques are beginning to be actively introduced in the A.E.C. industry, and the scalability of the technology is growing considerably. This study uses patent analysis based on objective data to find the right direction for Korean Scan-to-BIM technology by identifying the trends in Korea, the United States, Europe, and Japan. This was done using the WIPSON patent search system to find previous research on patent analysis related to building technology, theoretical consideration of scan-to-BIM technology, and published patents. We collected information, verified the process, and extracted valid patents. We used the effective patent data to analyze the annual trend of patent applications, national trends, and technological trends through the International Patent Classification (IPC) code, the types of the top 20 major applicants, and family patent trends.

• Journal of Animal Science and Technology
• /
• v.63 no.2
• /
• pp.199-210
• /
• 2021

A number of management issues can be used as drivers for change in order to improve animal welfare and nursing capacity of the hyperprolific sow. Group housing of sows during gestation is a recommended practice from the perspective of animal welfare. Related health issues include reproductive health and the locomotor system. It appears that management of pregnant sows in groups is challenging for a producer and considerable skill is required. We explored the benefits and challenges of group housing, including feeding issues. Increasing litter size requires additional attention to the mammary gland and its ability to provide sufficient nursing for the growing litter. We discuss the fundamentals of mammary development and the specific challenges related to the hyperprolific sow. We also address challenges with the farrowing environment. It appears that the old-fashioned farrowing crate is not only outdated in terms of welfare from the public's perspective, but also fails to provide the environment that the sow needs to support her physiology of farrowing, nursing, and maternal behaviour. Studies from our group and others indicate that providing the sow with a loose housing system adequate in space and nesting material, along with reasonable chance for isolation, can be considered as fundamental for successful farrowing of the hyperprolific sow. It has also been shown that management strategies, such as split suckling and cross fostering, are necessary to ensure proper colostrum intake for all piglets born alive in a large litter. We thus conclude that welfare and nursing capacity of the sow can be improved by management. However, current megatrends such as the climate change may change sow management and force the industry to rethink goals of breeding and, for instance, breeding for better resilience may need to be included as goals for the future.

• Research in Community and Public Health Nursing
• /
• v.32 no.2
• /
• pp.162-174
• /
• 2021

Purpose: The purpose of this qualitative study is to explore the changed parenting experiences of mothers of elementary school kids living in the aftermath of the COVID-19 outbreak in Korea. Methods: From July to August in 2020, 10 mothers parenting elementary school students under the COVID-19 were interviewed in depth. For data analysis, a phenomenological research methodology suggested by Colaizzi was used. Results: According to the analysis, the experiences of mothers consisted of four categories: the 'pain from the uncontrollable COVID-19', 'the problem of family relations due to the COVID-19 pandemic situation', 'standing firm against the drastic changes', and 'accepting the world changed by the COVID-19'. Conclusion: The findings in this study vividly represent the parenting experiences of mothers of elementary school students after the outbreak of COVID-19. As the pandemic persists, mothers parenting elementary school students feel complex emotions and experience exhaustion, but in the process, they found family members growing positively and trying to adjust to each other to overcome the crisis. To support positive adaptation to catastrophic situations, an institutional and political foundation is needed to develop a systematic crisis management program customized for mothers and families of elementary school students. The results of this study can be used as basic data when establishing national policies and support systems so that mothers parenting elementary school students can better adapt to and overcome crisis situations.

• Journal of Urban Science
• /
• v.10 no.1
• /
• pp.29-37
• /
• 2021

The number of old buildings older than 30 years in Korea continues to increase from 29.9% in 2005 to 38.8% in 2020. Considering the growing urban regeneration projects, urban maintenance projects, the suppression of urban expansion, and the lack of idle land in the city, the dismantling of old buildings is expected to increase further in the future. As major accidents at building dismantling sites continue to occur, related agencies are also strengthening safety management of building dismantling works. While physical safety management such as collapse and fall is strengthened, there is a relative lack of interest in the health of workers at dismantling sites due to environmental hazards. Since relevant laws stipulate that construction waste should be separated and discharged, old buildings need to be considered for environmental hazards such as fine dust, floating bacteria, and floating molds when dismantling. In this study, we intend to find important safety management elements in the management of building dismantling sites, measure environmental factors harmful to dismantling workers, and present basic data for the management of dismantling sites in the future. "Safety management" was the highest priority, followed by "dust," "vibration," "noise," "bacteria," and "smell." The perception of the importance of "physical damage prevention" with workers working on dismantling and managers managing the site came out similar, but the perception of "work efficiency" and "health disorder prevention" through environmental hazard management showed different priorities. In the process of dismantling, floating bacteria and floating mold were collected, cultured, and measured the concentration in the indoor air. The measurement was measured by dividing it into pre-dismantling and during dismantling.

• The Journal of the Korea Contents Association
• /
• v.21 no.5
• /
• pp.118-128
• /
• 2021

As interest in the audiobook market is growing, this study examined the influence of audiobook usage on purchase intention. An online survey was conducted in December 2020 targeting those in their 20s to 40s with experience using audiobooks. PLS-SEM was employed and the results are as follows. First, information, relaxation, and convenience motivation of audiobooks had a positive impact on user satisfaction. Second, while innovativeness of users had a positive impact on satisfaction, multitasking did not significantly affect satisfaction. Third, satisfaction had a positive impact on continued use and purchase intention. Finally, the continued use intention positively affected the purchase intention. This study is significant as an early study on the use of audiobooks. It is also meaningful in that it explored the process of evolving books in accordance with changes in technology and market demand.

• Membrane Journal
• /
• v.31 no.6
• /
• pp.384-392
• /
• 2021

Growing pollution due to industrialization leads to difficulties in survival of mankind. Generation of clean water from wastewater by membrane separation process is emerging cost efficient technology. Membrane prepared from renewable resources are in lots of demand to reduce burden on synthetic polymers which is one of the source of environmental pollution. Bacterial cellulose (BC) is very pure and distinct form of cellulose nanofibrils (CNF). Nanopapers prepared from CNF are used ad ultrafiltration (UF) and nanofiltration (NF) membrane for different applications. High crystallinity of BC gives rise to excellent mechanical property, an essential criterion for wastewater treatment membrane. In this review, BC based membrane for application in dye, oil, heavy metal and chemical removal from wastewater is discussed.

• The Journal of the Convergence on Culture Technology
• /
• v.8 no.1
• /
• pp.307-312
• /
• 2022

In line with the 4th industrial revolution and the innovative changes of the 21st century knowledge and information society, the education field where the 2015 revised curriculum is applied is facing a situation where it is necessary to consider various teaching and learning methods. Among them, interest in instructional design applying flipped learning suitable for future education is growing, but studies on classes using flipped learning in actual music and education are rare. In general music classes currently conducted in the elementary education field, it is insufficient to learn the musical function targeted in the class. Therefore, this study developed and validated an instructional design model for elementary school music and classes that applied flipped learning based on the ADDIE model, which is a systematic instructional design model, using the design and development research methodology. Based on the developed instructional design model, major issues for each stage were presented, and major educational implications in the development process were discussed.

• Korean Journal of Materials Research
• /
• v.31 no.11
• /
• pp.619-625
• /
• 2021

Cu₂ZnSn(S,Se)₄ (CZTSSe) based thin-film solar cells have attracted growing attention because of their earth-abundant and non-toxic elements. However, because of their large open-circuit voltage (V_oc)-deficit, CZTSSe solar cells exhibit poor device performance compared to well-established Cu(In,Ga)(S,Se)₂ (CIGS) and CdTe based solar cells. One of the main causes of this large V_oc-deficit is poor absorber properties for example, high band tailing properties, defects, secondary phases, carrier recombination, etc. In particular, the fabrication of absorbers using physical methods results in poor surface morphology, such as pin-holes and voids. To overcome this problem and form large and homogeneous CZTSSe grains, CZTSSe based absorber layers are prepared by a sputtering technique with different RTA conditions. The temperature is varied from 510 ℃ to 540 ℃ during the rapid thermal annealing (RTA) process. Further, CZTSSe thin films are examined with X-ray diffraction, X-ray fluorescence, Raman spectroscopy, IPCE, Energy dispersive spectroscopy and Scanning electron microscopy techniques. The present work shows that Cu-based secondary phase formation can be suppressed in the CZTSSe absorber layer at an optimum RTA condition.