• Advances in nano research
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• v.10 no.2
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• pp.115-128
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• 2021

In this article, free vibration behavior of electro-magneto-thermo sandwich Timoshenko beam made of porous core and Graphene Platelet Reinforced Composite (GPLRC) in a thermal environment is investigated. The governing equations of motion are derived by using the modified strain gradient theory for micro structures and Hamilton's principle. The magneto electro are under linear function along the thickness that contains magnetic and electric constant potentials and a cosine function. The effects of material length scale parameters, temperature change, various distributions of porous, different distributions of graphene platelets and thickness ratio on the natural frequency of Timoshenko beam are analyzed. The results show that an increase in aspect ratio, the temperature change, and the thickness of GPL leads to reduce the natural frequency; while vice versa for porous coefficient, volume fractions and length of GPL. Moreover, the effect of different size-dependent theories such as CT, MCST and MSGT on the natural frequency is investigated. It reveals that MSGT and CT have most and lowest values of natural frequency, respectively, because MSGT leads to increase the stiffness of micro Timoshenko sandwich beam by considering three material length scale parameters. It is seen that by increasing porosity coefficient, the natural frequency increases because both stiffness and mass matrices decreases, but the effect of reduction of mass matrix is more than stiffness matrix. Considering the piezo magneto-electric layers lead to enhance the stiffness of a micro beam, thus the natural frequency increases. It can be seen that with increasing of the value of WGPL, the stiffness of microbeam increases. As a result, the value of natural frequency enhances. It is shown that in hc/h = 0.7, the natural frequency for WGPL = 0.05 is 8% and 14% less than its for WGPL = 0.06 and WGPL = 0.07, respectively. The results show that with an increment in the length and width of GPLs, the natural frequency increases because the stiffness of micro structures enhances and vice versa for thickness of GPLs. It can be seen that the natural frequency for aGPL = 25 ㎛ and hc/h = 0.6 is 0.3% and 1% more than the one for aGPL = 5 ㎛ and aGPL = 1 ㎛, respectively.

• Korean Journal of Medicinal Crop Science
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• v.28 no.6
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• pp.421-427
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• 2020

Morus alba, Anti-obesity, C57BL/6 Mice, Expression, Flavonoid, Gene, Mulberry Background: The seed oil of Zanthoxylum schinifolium S. et Z. (sancho) is a traditional cooking oil that has long been sold at a very high price however, depending on the method of extraction and storage, this oil becomes rancid occurs very quickly. Therefore, this study aimed to find a material that prevents rancidity and improves the storage properties of sancho oil. Methods and Results: Sancho oil was extracted using an extraction press, and acid values were compared with commercially available vegetable oils, sancho oil had a higher acid value than other vegetable oils. A very high acid value was observed in sancho oil stored for 6 months, regardless of temperature, requiring an effective storage method. The high acid value and the decrease in turbidity of sancho oil are dependent on the days of sedimentation. Treatment with sodium bicarbonate by concentration resulted in minimal changes in acid value over time. However, minor differences were detected among the treatment concentrations. Ascorbic acid was added to maximize the effect of sodium bicarbonate, and it was observed that ascorbic acid did not improve the antioxidant effect. The sodium bicarbonate and ascorbic acid mixture resulted in minimal change in acid value at temperature up to 25℃. Conclusions: Sancho oil becomes rancid very quicky and requires efficient storage techniques. Sodium bicarbonate and ascorbic acid have been proven to be useful as safe anti-racidity agents without causing harm to humans.

• Structural Engineering and Mechanics
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• v.76 no.6
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• pp.687-708
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• 2020

Openings in steel plate shear walls (SPSWs) are usually used for decorative designs, crossing locations of multiple utilities and/or structural objectives. However, earlier studies showed that generating an opening in an SPSW has a negative effect on the cyclic performance of the SPSW. Therefore, this study proposes tripling or doubling the steel-sheet-plate (SSP) layer and stiffening the opening of the SPSW to provide a solution to undesirable opening effects, improve the SPSW performance and provide the infill option of potential strengthening measures after the construction stage. The study aims to investigate the impact of SSP doubling with a stiffened opening on the cyclic behaviour, expand the essential data required by structural designers and quantify the SPSW performance factors. Validated numerical models were adopted to identify the influence of the chosen parameters on the cyclic capacity, energy dissipation, ductility, seismic performance factors (SPF) and stiffness of the suggested method. A finite Element (FE) analysis was performed via Abaqus/CAE software on half-scale single-story models of SPSWs exposed to cyclic loading. The key parameters included the number of SSP layers, the opening size ratios corresponding to the net width of the SSP, and the opening shape. The findings showed that the proposed assembly method found a negligible influence in the shear capacity with opening sizes of 10, 15, 20%. However, a deterioration in the wall strength was observed for openings with sizes of 25% and 30%. The circular opening is preferable compared with the square opening. Moreover, for all the models, the average value of the obtained ductility did not show substantial changes and the ultimate shear resistance was achieved after reaching a drift ratio of 4.36%. Additionally, the equivalent sectional area of the SSP in the twin and triple configuration of the SPSWs demonstrated approximately similar results. Compared with the single SSP layer, the proposed configuration of the twin SSP layer with a stiffened opening suggest to more sufficiency create SSP openings in the SPSW compared to that of other configurations. Finally, a tabular SPF quantification is exhibited for SPSWs with openings.

• Journal of the Korea Society of Computer and Information
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• v.26 no.8
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• pp.91-101
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• 2021

This paper intends to draw implications for preparing for Post-Corona in the health field and policy fields as the global pandemic is experienced due to COVID-19. The purpose of this study is to analyze the news and trends of media companies through temporal analysis of the three infectious diseases, SARS-CoV, MERS-CoV, and SARS-CoV-2 (COVID-19), in which the domestic infectious disease preventive system was active throughout the first year of the outbreak. To this end, by using the news analysis program of the Korea Press Foundation 'Big Kinds', the number of news articles per year was digitized based on the period when each infectious disease had an impact on Korea, and major trends were implemented and analyzed in a word cloud. As a result of the analysis, the number of articles related to infectious diseases peaked when the World Health Organization (WHO) declared a warning and (suspicious) confirmed cases occurred. According to keyword and word cloud analysis, 'infectious disease outbreak and major epidemic areas', 'prevention authorities', and 'disease information and confirmed patient information' were found to be the main common features, and differences were derived from the three infectious diseases. In addition, the current status of the infodemic was identified by performing word cloud analysis on information in uncertainty. The results of this study are significant in that they were able to derive the roles of the health authorities and the media that should be preceded in the event of a new disease epidemic through previously experienced infectious diseases, and areas to be rearranged.

• 한국사회정책
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• v.24 no.2
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• pp.157-179
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• 2017

In Korea, 'spoon class discourse' has attracted public attention in the press and among young people, which reflects that mass awareness that the class status structure is clearly rooted in the society becomes widespread. Although income distribution has been improved since late 2000s, it is interesting that Korean people's subjective perception concerning class mobility and social justice has been worsemed. By using the survey data on people's perception of opportunity inequality, this study finds that Korean people have by and large negative subjective awareness regarding socio-economic opportunity inequality, magnitude of opportunity inequality, and achievement by efforts, and that the degree of the negative perception is greater in accordance with the people's subjective identification. The regression analysis reveals that the social status of respondents and their parents(-), experience of discrimination(+), age(-), and high education of college and above (+) have consistent effect over socio-economic opportunity inequality, magnitude of opportunity inequality, and achievement by efforts with statistical significance. More concretely, as people have lower subjective status identification at the time of parent generation and their own generation, as they have the experience of discriminatory misconduct, and as they are young and highly educated, they have negative or pessimistic perception regarding opportuinity inequality. In addition, it is revealed that the unemployed and non-regular workers have significantly negative perception on socio-economic opportunity inequality, magnitude of opportunity inequality, while negative perception on the magnitude of opportunity inequality and achievement by efforts is noticeable among high and middle income households.

• The Journal of the Korea Contents Association
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• v.21 no.6
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• pp.466-479
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• 2021

Fake news is flooded with fake news that mixes untrue falsehoods in whole or in part. In order to create a frame for political and social purposes, news is mainly created by combining facts with fakes, or news is created for the purpose of incitement to encourage distortion and hatred. In particular, some media, including over-the-air broadcasting, are expressing their political bias in a specific direction without hesitation. Even if the press has political bias, if it is based on the delivery of facts, a trusted media environment can be achieved under the mutual checks of conservatives and progressives. The May 18 Democratic Uprising is a painful history and fact of modern history, leaving remuneration and progress. Nevertheless, there is still a view that the May 18 Democratic Uprising is regarded as 'democracy movement' and 'violence'. This study analyzed how the conservative JoongAng Ilbo and the progressive Kyunghyang Shinmun Manpyeong deal with the May 18 Democratic Uprising. The Manpyeong of the two newspapers differs greatly from the viewpoint of the May 18 Democratic Uprising. The liberal tendency of the Kyunghyang Shinmun Manpyeong has great significance in that it reveals the essence of the event and satirizes the subject. On the other hand, the conservative JoongAng Ilbo Manpyeong cannot approach the nature of the case or the object of satire due to ambiguity.

• Journal of Digital Convergence
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• v.19 no.3
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• pp.177-185
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• 2021

This paper aimed to grasp what the percentage in the types of news stories on the online broadcast is, which was conducted by analyzing the news stories of 9 broadcasting websites on the Naver newsstand. For the analysis, a total of 270 days' samples were selected, including 30 days per broadcast on 9 broadcasting websites. For a method of analysis, One-way ANOVA was used to examine the difference among broadcasting websites. The analysis was made centering with priorities given to the type of news stories by the composition of language, the type of genre as a standard of stories, and so on. As a result of analysis, all the programs in the off-line broadcast have been produced and transmitted as a video-typed story, but a half of those in on-line broadcast have been made up of the stories composed of photo and text. The online newspaper has been producing a new type of news' story using video-typed story or computer graphic while the online broadcast has actively been utilizing stories composed of photos and text, which are types of newspaper's stories. From above-mentioned results, it can be understood that the boundary among media is getting more and more indistinct on the environment of online media, showing the phenomenon that the type of broadcast's stories is becoming old-fashioned.

• Geomechanics and Engineering
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• v.24 no.3
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• pp.215-226
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• 2021

To study the evolution mechanism of cracks in rocks with multiple defects, rock-like samples with multiple defects, such as strip-shaped through-going cracks and cavity groups, are used, and the crack propagation law and changes in AE (acoustic emission) and strain of cavity groups under different inclination angles are studied. According to the test results, an increase in the cavity group inclination angle can facilitate the initial damage degree of the rock and weaken the crack initiation stress; the initial crack initiation direction is approximately 90°, and the extension angle is approximately 75~90° from the strip-shaped through-going cracks; thus, the relationship between crack development and cavity group initiation strengthens. The specific performance is as follows: when the initiation angle is 30°, the cracks between the cavities in the cavity group develop relatively independently along the parallel direction of the external load; when the angle is 75°, the cracks between the cavities in the cavity group can interpenetrate, and slip can occur along the inclination of the cavity group under the action of the shear mechanism rupture. With the increase in the inclination angle of the cavity group, the AE energy fluctuation frequency at the peak stress increases, and the stress drop is obvious. The larger the cavity group inclination angle is, the more obvious the energy accumulation and the more severe the rock damage; when the cavity group angle is 30° or 75°, the peak strain of the local area below the strip-shaped through-going fracture plane is approximately three times that when the cavity group angle is 45° and 60°, indicating that cracks are easily generated in the local area monitored by the strain gauge at this angle, and the further development of the cracks weakens the strength of the rock, thereby increasing the probability of major engineering quality damage. The research results will have important reference value for hazard prevention in underground engineering projects through rock with natural and artificial defects, including tunnels and air-raid shelters.

• Structural Engineering and Mechanics
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• v.78 no.1
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• pp.41-52
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• 2021

Inelastic static pushover analysis has been used in the academic-research widely for seismic analysis of structures. Nowadays, the variety pushover analysis methods have been developed, including Modal pushover, Adaptive pushover, and Cyclic pushover, in which some weaknesses of the conventional pushover method have been rectified. In the conventional pushover analysis method, the effects of cumulative growth of cracks are not considered on the reduction of strength and stiffness of RC members that occur during earthquake or cyclic loading. Therefore, the Cyclic Pushover Analysis Method (CPA) has been proposed. This method is a powerful technique for seismic evaluation of regular reinforced concrete buildings in which the first mode of them is dominant. Since the bridges have different structures than buildings, their results cannot necessarily be attributed to bridges, and more research is needed. In this study, a cyclic pushover analysis with four loading protocols (suggested by valid references) by the Opensees software was conducted for seismic evaluation of two regular reinforce concrete bridges. The modeling method was validated with the comparison of the analytical and experimental results under both cyclic and dynamic loading. The failure mode of the piers was considered in two-mode of flexural failure and also a flexural-shear failure. Along with the cyclic analysis, conventional analysis has been studied. Also, the nonlinear incremental dynamic analysis (IDA) method has been used to examine and compare the results of pushover analyses. The time history of 20 far-field earthquake records was used to conduct IDA. After analysis, the base shear vs. displacement in the middle of the deck was drawn. The obtained results show that the cyclic pushover analysis method is able to evaluate an accurate seismic behavior of the reinforced concrete piers of the bridges. Based on the results, the cyclic pushover has proper convergence with IDA. Its accuracy was much higher than the conventional pushover, in which the bridge piers failed in flexural-shear mode. But, in the flexural failure mode, the results of each two pushover methods were close approximately. Besides, the cyclic pushover method with ACI loading protocol, and ATC-24 loading protocol, can provided more accurate results for evaluating the seismic investigation of the bridges, specially if the bridge piers are failed in flexural-shear failure mode.

• The Journal of the Korea Contents Association
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• v.21 no.8
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• pp.236-246
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• 2021

The purpose of this study was to help solve the problems of the high school credit system by exploring its operation plans for both career guidance and the effective and efficient operation of the high school credit system. The study's research method was literature research; it examined prior research, public hearings, press releases, the 2015 revised curriculum, and plans to promote the high school credit system by the Ministry of Education. To solve the problems facing the high school credit system, the curriculum should be organized as follows. First, it should be organized around general subjects. Second, students need to be able to study subjects related to their desired fields in depth. Third, it is necessary to confirm the basis for organizing the curriculum. Meanwhile, the following steps should be taken to improve the operation of the high school credit system for career guidance. First, a career curriculum committee for career learning and coaching should be formed and operationalized. Second, the teachers' work system should be restructured. Third, career aspirations should be identified, and directions for further study should be researched. Fourth, career and academic design guidance coaching books should be provided. Fifth, it is the role of the career and academic design guidance teacher. Sixth, emphasis should be placed on responsibility for subject selection and preparation for re-taking program.