• Journal of the Korean Crystal Growth and Crystal Technology
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• v.17 no.4
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• pp.156-159
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• 2007

The red emission properties of $Mn^{4+}$ doped $SrAl_{12}O_{19}$ prepared by the solid-state reaction was investigated, in order to verify its potential to act as the red emitting phosphor of white LEDs. The emission spectrum exhibits a narrow band between $600{\sim}700 nm $ with four sharp peaks occurring at about 643, 656, 666, 671 nm due to the $^2E\to^4A_2$ transition of $Mn^{4+}$. The excitation spectrum exhibits a broad band between $200{\sim}500 nm$ with three peaks occurring at about 338, 398 and 468 nm, respectively. Moreover, the relative emission intensity of $SrAl_{12}O_{19}:Mn^{4+}$ with or without $CaF_2$ and MgO fluxes measured at excitation source 390 nm. The relative emission intensity of $SrAl_{12}O_{19}:Mn^{4+}$ containing 0.67mol% MgO was approximately 30% higher than that of the base composition sample. Strontium hexa-aluminate measured at room temperature as a function of the substituted Mg concentration. MgO was added to replace part of the $Al_2O_3$. Also, the relative emission intensity of $SrAl_{12}O_{19}:Mn^{4+}$ containing 0.67 mol% MgO and 0.67 mol% $CaF_2$ was approximately about 48% higher than that of the base composition $SrAl_{12}O_{19}:Mn^{4+}$.

• The Journal of the Korea Contents Association
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• v.21 no.9
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• pp.149-163
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• 2021

The 4th industrial revolution refers to the next-generation industrial revolution led by information and communication technologies such as artificial intelligence (AI), Internet of Things (IoT), robot technology, drones, autonomous driving and virtual reality (VR) and it also has made a significant impact on the development of the advertising industry. However, the world is rapidly changing to a non-contact, non-face-to-face living environment to prevent the spread of COVID 19. Accordingly, the role of the 4th industrial revolution and advertising is changing. Therefore, in this study, text analysis was performed using Big Kinds to examine the 4th industrial revolution and changes in advertising before and after COVID 19. Comparisons were made between 2019 before COVID 19 and 2020 after COVID 19. Main topics and documents were classified through LDA topic model analysis and Word2vec, a deep learning technique. As the result of the study showed that before COVID 19, policies, contents, AI, etc. appeared, but after COVID 19, the field gradually expanded to finance, advertising, and delivery services utilizing data. Further, education appeared as an important issue. In addition, if the use of advertising related to the 4th industrial revolution technology was mainstream before COVID 19, keywords such as participation, cooperation, and daily necessities, were more actively used for education on advanced technology, while talent cultivation appeared prominently. Thus, these research results are meaningful in suggesting a multifaceted strategy that can be applied theoretically and practically, while suggesting the future direction of advertising in the 4th industrial revolution after COVID 19.

• Journal of Digital Convergence
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• v.18 no.12
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• pp.335-341
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• 2020

This study aims to identify the importance and degree of performance of COVID19 infection control educational program for 4th grade nursing college students, and to prepare the basic data for developing COVID19 infection control nursing education program based on this study. Data were collected from January 6 to January 30, 2020 by using structured questionnaire from 72 senior nursing students at "A" City Nursing College. The overall average of importance of COVID19 infection control nursing was 4.4 out of 5, and the overall average of performance was 2.4 out of 5. The greatest difference in importance and performance were the sectors of personal protection(equipment dressing & undessing) and collecting safe sample. By analyzing the needs for COVID19 infection control nursing of nursing college students It is used as the basic data for the development of simulation education programs by improving performance of both personal protection and collecting safety samples.

• YAKHAK HOEJI
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• v.12 no.3_4
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• pp.76-84
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• 1968

When 19-hydroxycholesterol acetate was added into CSD-10 in Nutrient Broth or in a mineral salts medium consisting of KH$_{2}$PO$_{4}$(0.1%), $K_{2}$HPO$_{4}$(0.1%), NH$_{4}$NO$_{3}$(0.1%), MgSO$_{4}$(0.02%), CaCl$_{2}$(0.002%), and FeCl$_{3}$(0.005%), a substantial amount of 19-hydroxyandrost-4-ene-3,17-dione was accumulated prior to accumulation of estrone. From this result and all of previous works, a tentative degradation pathway of 19-hydroxycholesterol acetate to estrone by CSD-10 was derived. 19-hydroxyandrost-4-ene-3,17-dione seems to be an attractive intermediate for the synthesis of 19-norsteroids.

• Genomics & Informatics
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• v.19 no.4
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• pp.35.1-35.2
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• 2021

• Korean Journal of Materials Research
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• v.31 no.2
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• pp.61-67
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• 2021

Fabrication of a ferromagnetic composite powder for the magnesium and BaFe12O19 system by mechanical alloying (MA) is investigated at room temperature. Mixtures of Mg and BaFe12O19 powders with a weight ratio of Mg:BaFe12O19 = 4:1, 3:2, 2:3 and 1:4 are used. Optimal MA conditions to obtain a ferromagnetic composite with fine microstructure are investigated by X-ray diffraction, differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM) measurement. It is found that Mg-BaFe12O19 composite powders in which BaFe12O19 is dispersed in Mg matrix are successfully produced by MA of BaFe12O19 with Mg for 80 min. for all compositions. Magnetization of Mg-BaFe12O19 composite powders gradually increases with increasing the amounts of BaFe12O19, whereas coercive force of MA powders gradually decreases due to the refinement of BaFe12O19 powders with MA time for all compositions. However, it can be seen that the coercivity of Mg-BaFe12O19 MA composite powders with a weight ratio of Mg:BaFe12O19=4:1 and 3:2 for MA 80 min. are still high, with values of 1260 Oe and 1320 Oe compared to that of Mg:BaFe12O19=1:4. This clearly suggests that the refinement of BaFe12O19 powders during MA process for Mg:BaFe12O19=4:1 and 3:2 tends to be suppressed due to ductile Mg powders.

• Korean Journal of Soil Science and Fertilizer
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• v.33 no.1
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• pp.47-51
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• 2000

2,4,5-trichlorophenoxyacetic acid (2,4,5-T)-degrading bacterial strains were isolated from rice field and field in suburbs of Taejon. Of the total 100 isolates, 19 strains were selected by fast growth on solid minimal media containing 2,4,5-T as a sole of carbon and energy, and they were identified to genus level. 11 strains were identified as Pseudomonas, 4 strains as Acinetobacter, 1 strains were as Alcaliagenes and 3 strains were not identified. Strains MU19 and MU92 which were identified as Pseudomonas were capable of degradation for 4 kinds of chlorinated aromatic hydrocarbons, 2,4-D, 2,4,5-T, MCPA and 3CB. Acinetobacter sp. MU38 showed the highest degradability in liquid minimal media at 48 hours after inoculation, and Pseudomonas spp. MU19. MU57, MU73, and MU92 were able to degrade carbon source at higher rates. As the results Acinetobacter sp. MU38 and Pseudomonas spp. MU19 and MU92 were capable of biodegradation for broad range of halogenated aromatic hydrocarbons, and had higher rates of degradation for 2,4,5-T.

• International Journal of Computer Science & Network Security
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• v.22 no.4
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• pp.39-46
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• 2022

The spread of Omicron, a mutated version of COVID-19 across several countries is leading to the discussion of lockdown once again for curbing the spread of the new virus. In this context, this research is showing the impact of lockdown for the successful control of the COVID-19 pandemic in Saudi Arabia. The outbreak of the COVID-19 pandemic around the globe has affected Saudi Arabia with around 2,37,803 confirmed cases within the initial 4 months of transmission. Saudi Arabia has announced a 21-day lockdown from March 23, 2020, to reduce the transmission of the COVID-19 pandemic. Machine Learning-based, Multinomial logistic regression was applied to understand the relationship between daily COVID-19 confirmed cases and lockdown in the 17 most-affected cities of KSA. We used secondary published data from the Ministry of Health, KSA daily dataset of COVID-19 confirmed case counts. These 17 cities were categorized into 4 classes based on lockdown dates. A total of three scenarios such as night lockdown, full lockdown, and no lockdown have been analyzed with the total number of confirmed cases with 4 classes. 15 out of 17 cities have shown a strong correlation with a confidence interval of 95%. These findings provide evidence that the COVID-19 pandemic may be partially suppressed with lockdown measures.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.3
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• pp.625-632
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• 2024

This paper analyzed the changes in the curriculum of computer and software-related majors that educate the core ICT technologies needed for the 4th Industrial Revolution, before and after the COVID-19 pandemic. According to the standard classification of university education units, 172 majors classified into Applied Software Engineering, Computer Science·Computer Engineering, and Artificial Intelligence Engineering were targeted, and the curricula of 2023 and 2019 were compared and analyzed. As a result of the analysis, the introduction of the related curriculum for each curriculum group increased by about 2.6%p before and after the COVID-19 pandemic (2023 84.2%, 2019 81.6%). and the 4th Industrial Revolution response index increased by 9.5 points (37.0 in 2023, 27.5 in 2019)

• Clinical and Experimental Pediatrics
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• v.64 no.7
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• pp.364-369
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• 2021

Background: As the coronavirus disease 2019 (COVID-19) outbreak continues to evolve, it is crucially important for pediatricians to be aware of the differences in demographic and clinical features between COVID-19 and influenza A and B infections. Purpose: This study analyzed and compared the clinical features and laboratory findings of COVID-19 and influenza A and B infections in children. Methods: This retrospective study evaluated the medical data of 206 pediatric COVID-19 and 411 pediatric seasonal influenza A or B patients. Results: COVID-19 patients were older than seasonal influenza patients (median [interquartile range], 7.75 [2-14] years vs. 4 [2-6] years). The frequency of fever and cough in COVID-19 patients was lower than that of seasonal influenza patients (80.6% vs. 94.4%, P<0.001 and 22.8 % vs. 71.5%, P<0.001, respectively). Ageusia (4.9%) and anosmia (3.4%) were present in only COVID-19 patients. Leukopenia, lymphopenia, and thrombocytopenia were encountered more frequently in influenza patients than in COVID-19 patients (22.1% vs. 8.5%, P=0.029; 17.6% vs. 5.6%, P=0.013; and 13.2% vs. 5.6%, P=0.048, respectively). Both groups showed significantly elevated monocyte levels in the complete blood count (70.4% vs. 69.9%, P=0.511). Major chest x-ray findings in COVID-19 patients included mild diffuse ground-glass opacity and right lower lobe infiltrates. There were no statistically significant intergroup differences in hospitalization or mortality rates; however, the intensive care unit admission rate was higher among COVID-19 patients (2.4% vs. 0.5%, P=0.045). Conclusion: In this study, pediatric COVID-19 patients showed a wide range of clinical presentations ranging from asymptomatic/mild to severe illness. We found no intergroup differences in hospitalization rates, oxygen requirements, or hospital length of stay; however, the intensive care unit admission rate was higher among COVID-19 patients.