• Korean Chemical Engineering Research
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• v.59 no.3
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• pp.417-428
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• 2021

The combustion characteristics of anthracite, which follow a complex process with low reactivity, must be considered through the dynamic behavior of circulating fluidized bed (CFB) boilers. In this study, computational fluid dynamics (CFD) simulation was performed to analyze the combustion characteristics of anthracite in a pilot scale 0.1 MW_th Oxy-fuel circulating fluidized bed (Oxy-CFB) boiler. The 0.1MW_th Oxy-CFB boiler is composed of combustor (0.15 m l.D., 10 m High), cyclone, return leg, and so on. To perform CFD analysis, a 3D simulation model reactor was designed and used. The anthracite used in the experiment has an average particle size of 1,070 ㎛ and a density of 2,326 kg/m³. The flow pattern of gas-solids inside the reactor according to the change of combustion environment from air combustion to oxygen combustion was investigated. At this time, it was found that the temperature distribution in air combustion and oxygen combustion showed a similar pattern, but the pressure distribution was lower in oxygen combustion. addition, since it has a higher CO₂ concentration in oxygen combustion than in air combustion, it can be expected that carbon dioxide capture will take place actively. As a result, it was confirmed that this study can contribute to the optimized design and operation of a circulating fluidized bed reactor using anthracite.

• Journal of the Korean Institute of Landscape Architecture
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• v.49 no.2
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• pp.41-50
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• 2021

This study was conducted to see the differences of park users by classifying them with their park use frequency in terms of park use, management policy and perception, using the same survey results conducted in 2014 and 2020. Research was conducted on urban parks in Yangju, South Korea, and 740 in 2014 and 431 in 2000 survey results were used. After classifying the high-use and low-use groups according to park use frequency, this study compared the demographic differences and park use method differences according to the group, the recognition differences for the future park management direction between the two groups were analyzed and compared using statistical analysis by year. The results showed that the park's quantitative expansion and accessibility improvements were the most important issues in 2014, while the importance of park management, such as checking and improving aging facilities, providing various programs, and creating a themed neighborhood park that could reveal the identity of the area, was increased in 2020. Despite recognizing the importance of persistent management in the case of high-use groups, the results showed that they were less willing to participate in park management programs compared to less-use groups, which showed the need for a discussion of how to involve high-use groups for long term park management. This study contribute the body of literature that it seeks to understand differences of park user in terms of their park use frequency. However, in future studies, analyzing the differences of park users through a short-term study is required.

• Journal of the Korean School Mathematics Society
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• v.24 no.1
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• pp.107-126
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• 2021

Lexicon is closely related to human thinking. In particular, a classroom lexicon results from objectifying the teaching-learning activity in classrooms, allowing humans to recognize and explore the activities and phenomena in classrooms explicitly. Therefore, using the lexicon and clarifying what the words mean is to enhance the understanding of teaching activities. The International Classroom Lexicon Project investigates and identifies each country's mathematics classroom lexicon, where ten countries participated. The purpose of this current study is to compare the differences in perceptions between teachers and pre-service teachers about the Korean classroom lexicon previously investigated as a part of the international collaborative project. By comparing the responses of 147 teachers and 127 pre-service teachers, the degree of familiarity with pedagogical terms and the frequency of occurrence or usage in classrooms were compared and analyzed to understand the recognition of pre-service teachers' pedagogical terms. Finally, we also discuss reflections on Korean mathematics teaching practices in Korea.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.371-378
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• 2021

In this study, in order to analyze the spatial distribution of cold water occurred in the Southeast Sea of Korea, the K-means clustering method was used to analyze the ocean observatory buoy of Gori and Yangpo and GHTSST Level 4 from 2016 to 2018. The buoy data was used to identify the change in sea water temperature and the cold water occurrence at Gori and Yangpo in the Southeast Sea. As a result, the sea water temperature of Gori and Yangpo decreased equally at the cold water occurrence. Therefore, the reciprocal of the sea water temperature and the variance of SST were compared to see the changes of SST when the cold water occurs. When the reciprocal of the sea water temperature increases, the dispersion of SST also increases. Through this, it can be seen that there is a change in the water temperature distribution of SST in the sea when the cold water occurs. After that, K-means clustering was used to classify the cold water. After analyzing the optimal K value for clustering by using the Elbow method, it was possible to classify a region with cold water. Through this, it is estimated that the spatial distribution and diffusion range of the cold water, and it can be estimated and used in future studies to identify damage caused by the cold water and predict spatial spread.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.5
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• pp.60-67
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• 2021

According to the 「Guidelines of Structural Design for Piloti Building」 of the Ministry of Land, Infrastructure and Transport (2018), the natural period of middle and low rise building of upper-walled lower frame type, such as the domestic multiplex house in piloti style, is suggested for safety to apply the existing code formula of the wall structure. However, the current code formula of the wall structure was provided based on actual measurement of high-rise wall-type structures that mainly exhibit bending behavior. So it is considered that it is not suitable for a piloti-type house with four stories or less, where the wall behaves in shear. See also Park et al. (2000) confirmed that the effect of the lower frame part is greater than that of the upper wall part in the natural period of complex structures with 10 or more floors through analytical studies. Therefore, in this study, in order to examine the effect of the lower frame on the natural period of the middle and low-rise piloti structure, the estimation of natural period by the finite element analysis, approximation formula and ccurrent code formula was performed for the target structures with the shear and flexural stiffness of the upper wall and the shear stiffness of the lower frame as variables. As result, it was found that the change in the shear stiffness of the lower frame had a greater effect on the natural period of the whole building than the change in the bending or shear stiffness of the upper wall.

• The Journal of the Korea Contents Association
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• v.21 no.7
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• pp.637-649
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• 2021

This study aims to see, a 10-weeks program of Body Stability Exercise(BSE) was conducted on 21 male handball players at Muan Y High School and then, the results of changes in Visual Response Speed Test, Functional Movement Screen, Y-Balance Test, and Vital Capacity were observed, compared and analyzed to provide follow-up management and training data that can be used to reduce injuries and improve performance. After training, strength and quickness were increased significantly and reaction time was significantly shortened (p<0.001). The total score of Functional Movement Screen was increased from 10.43±1.16, before training to 12.05±1.07 after training, which was statistically significant(p<0.001). Y-Balance Test was significantly increased from 89.18±6.99 before training to 91.39±7.33 after training(p<0.001). The Vital Capacity increase was also shown to be more than statistically significant(p<0.001). The 10-week BSE program improved speed, agility, Functional Movement Screen, Y-Balance Test, and Vital Capacity. In conclusion, it's can prevent or reduce injuries and performance could be improved while playing handball.

• Land and Housing Review
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• v.12 no.2
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• pp.121-139
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• 2021

Technical documents in the construction field are changing from paper documents to electronic ones. As a result, the industry witnesses a trend of using portable electronic devices in searching or retrieving necessary information such as relevant regulations. Despite the improvement in the accessibility to general technical documents, a limitation is still found in accessing the electronic documents on the regulations. We see the barrier for field engineers to enhance their technical knowledge. One of major barriers is that videos, animations, and virtual reality information to enhance the visual understanding of technical content related to regulations are not linked. It is the interactive electronic technical manual (IETM) that can address such issues. The IETM is an electronic document system that enables real-time information acquisition while operating in the form of conversations with users by linking multimedia functions to document types such as specifications and guidelines. This study establishes a model of the IETM that can be operated in the planning stage of a construction project. The study also verifies its usability with a hypothetical case study. This study aims to improve the usability of the IETM in the construction project by analyzing the application effect of the IETM using the AHP technique.

• Genes and Genomics
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• v.40 no.12
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• pp.1373-1382
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• 2018

Hanwoo and Chikso are classified as Korean native cattle breeds that are currently registered with the Food and Agriculture Organization. However, there is still a lack of genomic studies to compare Hanwoo to Chikso populations. The objective of this study was to perform genome-wide analysis of Hanwoo and Chikso populations, investigating the genetic relationships between these two populations. We genotyped a total of 319 cattle including 214 Hanwoo and 105 Chikso sampled from Gangwon Province Livestock Technology Research Institute, using the Illumina Bovine SNP50K Beadchip. After performing quality control on the initially generated datasets, we assessed linkage disequilibrium patterns for all the possible SNP pairs within 1 Mb apart. Overall, average $r^2$ values in Hanwoo (0.048) were lower than Chikso (0.074) population. The genetic relationship between the populations was further assured by the principal component analysis, exhibiting clear clusters in each of the Hanwoo and Chikso populations, respectively. Overall heterozygosity for Hanwoo (0.359) was slightly higher than Chikso (0.345) and inbreeding coefficient was also a bit higher in Hanwoo (-0.015) than Chikso (-0.035). The average $F_{ST}$ value was 0.036 between Hanwoo and Chikso, indicating little genetic differentiation between those two breeds. Furthermore, we found potential selection signatures including LRP1B and NTRK2 genes that might be implicated with meat and reproductive traits in cattle. In this study, the results showed that both Hanwoo and Chikso populations were not under severe level of inbreeding. Although the principal component analysis exhibited clear clusters in each of the populations, we did not see any clear evidence that those two populations are highly differentiated each other.

• International Area Studies Review
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• v.20 no.1
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• pp.23-51
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• 2016

This study analyzed the expected economic effects of the Korea-GCC FTA and sought strategies for industrial cooperation. To see the economic effects of Korea-GCC FTA, we analysed the effect of the oil tariff reduction of economy by Vector Autoregression(VAR) model. The estimation results shows that following the abolishment of the tariff on crude oil imports, GDP, GNI and consumption are expected to grow by 0.212%, 0.389% and 0.238%, respectively. Meanwhile, investment, export and import are estimated to drop by 0.462%, 0.413% and 0.342%, respectively. As for prices, producer prices are to rise by 6.356%p, whereas consumer prices fall by 2.996%p. In short, the Korea-GCC FTA and resultant abolishment of the tariff on crude oil imports followed by the decline in crude oil prices will result in declining prices whilst macroeconomic indices, such as GDP, GNI and consumption, will increase exerting positive effects on domestic economic growth. Also, it is necessary to proactively respond to GCC member states' industrial diversification policies for FTA-based industrial cooperation to diversify the sources of crude oil and natural gas imports for further resource risk management.

• 기호학연구
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• no.57
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• pp.59-90
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• 2018

This paper examines the discussions related to image and signification through the theories of Roland Barthes. We have already been able to see through the studies of Semiotics and Anne H?nault that the denotation is distinguished from the connotation in the linguistic dimension. Through the analysis of the advertising image of Barthes, we have seen that the syntagmatic relationship can make the sense of the image objective. From this study, we also emphasized that it is possible to subjectively interpret images that deviate from the syntagmatic relationship. In addition, we examined the concepts of Studium and Punctum by Barthes. With this we have found that the definition of a personal meaning to objects has a theoretically clear position. Finally, we have been able to understand the concept of 'le sens obtus' through the article ${\ll}$ Le troisi?me sens ${\gg}$. The notion of 'sens obtus' makes it possible to realize that the objective and clear sense of object is not the one chosen primarily from the subject. By facing an object such as an image to be interpreted, the subject is placed in a situation where he is not compelled to choose a meaning but rather he chooses one of the possible senses. This makes it clear that the semantic levels provided by semiotic theories are limited to the analytic dimension.