• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.1-8
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• 2020

Centrifugal pump is a facility that transfers energy to fluid through centrifugal force, which is usually generated by rotating the impeller at high speed, and is a major process facility used in many LNG production bases such as vaporization seawater pump, industrial water and fire extinguishing pump using seawater. to be. Currently, pumps in LNG plant sites are subject to operating conditions that vary depending on the amount of supply desired by the customer for a long period of time. Pumps in particular occupy a large part of the consumption strategy at the plant site, and if the optimum operation condition is not available, it can incur enormous energy loss in long term plant operation. In order to solve this problem, it is necessary to identify the performance deterioration factor through the flow analysis and the result analysis according to the fluctuations of the pump's operating conditions and to determine the optimal operation efficiency. In order to evaluate operation efficiency through experimental techniques, considerable time and cost are incurred, such as on-site operating conditions and manufacturing of experimental equipment. If the performance of the pump is not suitable for the site, and the performance of the pump needs to be reduced, a method of changing the rotation speed or using a special liquid containing high viscosity or solids is used. Especially, in order to prevent disruptions in the operation of LNG production bases, a technology is required to satisfy the required performance conditions by processing the existing impeller of the pump within a short time. Therefore, in this study, the rotation difference of the pump was applied to the ANSYS CFX program by applying the modified 3D modeling shape. In addition, the results obtained from the flow analysis and the curve fitting toolbox of the MATLAB program were analyzed numerically to verify the outer diameter correction theory.

• Korean Journal of Environment and Ecology
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• v.36 no.2
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• pp.177-201
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• 2022

Following the adoption of the global plant conservation strategies at the Conference of the Parties for Biodiversity Conservation, diligent actions to achieve each targets are actively carried out. In particular, the need for ecological conservation research to achieve targets 2 and 7 of GSPC-2020 has increased. The priority taxa to accomplish the objectives of GSPC-2020 are rare and endemic plants. In particular, endemic plants with limited distribution in specific regions are evaluated to face a high risk of extinction. To address the necessity to preserve endemic plants, we investigated the distribution of Prunus choreiana H. T. Im, a Korean endemic plant. After that, we examined the vegetational environment of the habitat of P. choreiana and evaluated its population structure. The productivity of its fruits and the effects of pollinators on fruit production were evaluated as well. The fruiting ratio was calculated based on the number of flowers produced. Lastly, we observed the annual growth characteristics of P. choreiana. The habitats of P. choreiana did not show a specific type of vegetation. All of them were located in a limestone area of Gangwon-do in the central Korean Peninsula and occupied a site where the coverage of the tree layer and the sub-tree layer was not high or did not exist. The population structure of P. choreiana contained a high proportion of mature plants capable of producing fruits and a low proportion of seedlings and Juvenile plants. We found that the production of fruits required pollinators and was affected by the performance of each plant. Although P. choreiana produces many flowers, only a maximum of 20% and only 2-6% on average bear fruits. These flowering characteristics may be due to pollinators' low abundance and activity during the flowering season (between mid-March and early April), suggesting that many flowers are needed to attract more pollinators. We rarely observed the re-establishment of seedlings in the population of P. choreiana. Despite that, we predict the population to persist owing to its long lifespan and periodic production of numerous fruits. However, if the tree layer and sub-tree layer in competing status with P. choreiana increase their crown density, they are expected to inhibit the growth of P. choreiana and affect the risk of its extinction. Therefore, the current changes in the vegetational environment of the habitats are expected to decrease the number and extent of P. choreiana in the long term. The results of this study may serve as primary and important data necessary for the achievement of GSPC-2020 objectives.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.4
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• pp.356-368
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• 2021

To understand the temporal variation of phytoplankton communities in a coastal area, the biomass and diversity were weekly investigated in the inner bay of Yeong-do, Busan. In the study area, chlorophyll a concentration ranged from 0.43~7.58 mg m^-3 during the study, indicating the study area was in mesotrophic or eutrophic status. The fractions of chlorophyll a occupied by large phytoplankton (> 3 ㎛ diameter) exhibited an average of 80% of total chlorophyll a in this study. Among the large phytoplankton, while Bacillariophyta was the most dominant in spring and summer, Cryptophyceae prevailed in the fall and winter. On the contrary, in the picophytoplankton community less than 3 ㎛ in diameter, Mamiellophyceae was the most dominant in most seasons, Cryptophyceae was relatively high with an average of 17.7 ± 17.6% throughout the year, but seasonal variations were large. Dinophyceae rarely occupied a higher fraction up to 60.4% of the picophytoplankton community. By weekly monitoring at a coastal station for 13 months, it is suggested that phytoplankton communities in coastal waters could be changed on a short time scale. If data are steadily accumulated at the time-series monitoring site for a long time, these will provide important data for understanding the long-term dynamics of phytoplankton as well as the impact of climate and environmental changes.

• Journal of Korean Society of Forest Science
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• v.102 no.2
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• pp.210-215
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• 2013

Litterfall production represents a major contribution of carbon and nutrient cycling in forest ecosystems. This study was carried out to determine the litterfall production in a broadleaved deciduous forest at the Mt. Keumsan Long Term Ecological Research (LTER) site, Southern Korea. Littefall was collected monthly or bimonthly from the site for 7 years from 2004 to2010. Leaf and reproductive (catkins) litters showed a seasonal variation, but litters of needle, branch, and barks were not changed across the seasons. Annual leaf litter of Quercus serrata and Carpinus laxiflora were significantly different (p<0.05) but that of C. cordata, Chamaecyparis obtusa, and Pinus thunbergii was not significantly changed for 7 years (p>0.05). Annual average litterfall production was 5,223 kg/ha, but annual variations were very large with minimum of 4,110 kg/ha/yr in 2004 and maximum of 6,002 kg/ha/yr in 2007. Total litterfall comprised of 2,323 kg/ha/yr in Q. serrata, 442 kg/ha/yr in C. laxiflora, 157 kg/ha/yr in C. cordata, 131 kg/ha/yr in Acer pseudosieboldianum, 390 kg/ha/yr in other deciduous tree species, 74 kg/ha/yr in P. thunbergii, 37 kg/ha/yr in C. obtusa, 672 kg/ha/yr in branches, 515 kg/ha/yr in miscellaneous, 448 kg/ha/yr in reproductive parts, and 54 kg/ha/yr in barks. respectively. The results indicate that litterfall production of the Mt. Keumsan LTER site was yearly fructurated with the positive linear relationship between leaf or total litterfall and annual mean temperature if no disturbance such as a typoon, and was lower than that of other Korean LTER sites.

• Journal of Korean Society of Forest Science
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• v.103 no.1
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• pp.37-42
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• 2014

Fine root distribution was investigated in Pinus densiflora stands using soil core sampling and minirhizotrons, and conversion factors and regression equations were developed for converting minirhizotron data into fine root biomass. Fine root biomass was measured by soil core sampling from October, 2012 to September, 2013 once a month except for the winter, and surface area of fine roots was estimated by minirhizotrons from May to August, 2013 once a month. Fine root biomass and surface area were significantly higher in the upper soil layers than in the lower soil layers. Fine root biomass showed seasonal patterns; the mean fine root biomass ($kg{\cdot}ha^{-1}$) in summer (3,762.4) and spring (3,398.0) was significantly higher than that in autumn (2,551.6). Vertical and seasonal patterns of fine root biomass might be related to the soil bulk density, nutrient content and temperature with soil depth, and seasonal changes of soil and air temperature. Conversion factors (CF) between fine root surface area from minirhizotron data and fine root biomass from soil core sampling were developed for the three soil depths. Then a linear regression equation was developed between the predicted fine root biomass using CF and the measured fine root biomass (y = 79.7 + 0.93x, $R^2=0.81$). We expect to estimate the long-term dynamics of fine roots using CF and regression equation for P. densiflora forests in Korea.

• International Journal of Computer Science & Network Security
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• v.21 no.12spc
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• pp.664-674
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• 2021

The relevance of this scientific research is determined by the negative impact of the COVID-19 pandemic on the current trends and dynamics of world tourism development. This article aims to identify patterns of development of the modern tourist market, analysis of problems and prospects of development in the context of the COVID-19 pandemic. Materials and methods. General scientific methods and methods of research are used in the work: analysis, synthesis, comparison, analysis of statistical data. The analysis of the viewpoints of foreign and domestic authors on the research of the international tourist market allowed us to substantiate the actual directions of tourism development due to the influence of negative factors connected with the spread of a new coronavirus infection COVID-19. Economic-statistical, abstract-logical, and economic-mathematical methods of research were used during the process of study and data processing. Results. The analysis of the current state of the tourist market by world regions was carried out. It was found that tourism is one of the most affected sectors from COVID-19, as, by the end of 2020, the total number of tourist arrivals in the world decreased by 74% compared to the same period in 2019. The consequence of this decline was a loss of total global tourism revenues by the end of 2020, which equaled $1.3 trillion. 27% of all destinations are completely closed to international tourism. At the end of 2020, the economy of international tourism has shrunk by about 80%. In 2020 the world traveled 98 million fewer people (-83%) relative to the same period last year. Tourism was hit hardest by the pandemic in the Asia-Pacific region, where travel restrictions are as strict as possible. International arrivals in this region fell by 84% (300 million). The Middle East and Africa recorded declines of 75 and 70 percent. Despite a small and short-lived recovery in the summer of 2020, Europe lost 71% of the tourist flow, with the European continent recording the largest drop in absolute terms compared with 2019, 500 million. In North and South America, foreign arrivals declined. It is revealed that a significant decrease in tourist flows leads to a massive loss of jobs, a sharp decline in foreign exchange earnings and taxes, which limits the ability of states to support the tourism industry. Three possible scenarios of exit of the tourist industry from the crisis, reflecting the most probable changes of monthly tourist flows, are considered. The characteristics of respondents from Ukraine, Germany, and the USA and their attitude to travel depending on gender, age, education level, professional status, and monthly income are presented. About 57% of respondents from Ukraine, Poland, and the United States were planning a tourist trip in 2021. Note that people with higher or secondary education were more willing to plan such a trip. The results of the empirical study confirm that interest in domestic tourism has increased significantly in 2021. The regression model of dependence of the number of domestic tourist trips on the example of Ukraine with time tendency (t) and seasonal variations (Turˆt = 7288,498 - 20,58t - 410,88∑5) it forecast for 2020, which allows stabilizing the process of tourist trips after the pandemic to use this model to forecast for any country. Discussion. We should emphasize the seriousness of the COVID-19 pandemic and the fact that many experts and scientists believe in the long-term recovery of the tourism industry. In our opinion, the governments of the countries need to refocus on domestic tourism and deal with infrastructure development, search for new niches, formats, formation of new package deals in new - domestic - segment (new products' development (tourist routes, exhibitions, sightseeing programs, special rehabilitation programs after COVID) -19 in sanatoriums, etc.); creation of individual offers for different target audiences). Conclusions. Thus, the identified trends are associated with a decrease in the number of tourist flows, the negative impact of the pandemic on employment and income from tourism activities. International tourism needs two to four years before it returns to the level of 2019.

• 한국노년학
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• v.38 no.4
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• pp.1035-1055
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• 2018

The purpose of this study is to investigate the relationship between public care and family care. Public care for older adults began in 2008 with the implementation of the Long-Term Care insurance in South Korea. Although the expansion of public care has the purpose of reducing the care burden for the family, it is not easy to say whether the developments of public care system reduce the amount of family care for older family members. Theoretically, public care and family care are expected to have various relationships depending on the degree of the role and function(substitution, hierarchical compensatory, task specific, supplementation, complementarity). And literatures have showed inconsistent results depending on the country, data, and methods. In this study, we analyzed the relationship between two care types focusing on home care services for older persons. Analyses were based on data from the second(2008) to sixth(2016) waves of Korean Longitudinal Study of Ageing(KLoSA). To investigate elderly care dynamics in the households, we pooled the data for four changes between two periods(2008-2010, 2010-2012, 2012-2014, and 2014-2016). This study used an analytic sample of 262 older adults, who are aged 55 over and experienced public care at least one point of time. We used Fixed-Effects(FE) model to analyze the differences within the same individuals under the condition that time-invariant unobserved factors are controlled. This study distinguished the cases of entry into public care and other cases of exiting public care. The results showed that older people who are dependent on public care are less dependent on family care than before. In both entry and exit groups, negative relations were maintained, but in the entering stage of public care, the degree of negative relations was relatively small, whereas in the stage of maintaining or departing from public care, relatively negative relations were strong. At the beginning periods, even though public care increased, family care did not decrease significantly. On the other hand, at the time of ending public care and relying on family care, family care increased significantly. The results of this study show that the relationship between public care and family care is close to hierarchical compensatory model and varies according to the stage of caring transition. Also, it was found that the cases of transition from public care to family care have the biggest burden of elderly care than other groups.

• Korean Association of Arts Management
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• no.51
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• pp.5-34
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• 2019

This study is a qualitative study conducted to identify environmental factors that impede emerging artists' ongoing creative activities, focusing on the local cultural ecosystem that they are part of. By doing so, we tried to understand the dynamics between key stake holders in the ecosystem that these young artists interact with and how they build and perceive their own, local cultural environment. The central research question of this study is: what factors impede the continuous creative activities of young artists and what causes them to leave local art scenes? The research was conducted thoroughly on the basis of emerging artists' experience and perspectives and applied to Creative Sector Holistic Model for analysis. The data of this research were collected based on two national-funding projects to support young artists from 2016 to 2018. The main research method of this study was interviews: official and casual interviews were executed with 29 young artists aged 20-34 who work in the fields of painting, literature, sculpture, video, korean traditional music, visual design and crafts. For the analysis of the data, the Creative Sector Holistic Model(Wyszomirski, 2008), which had applied the ecological logic to the creative industries, was applied. The result of this study shows that economic difficulties were not the only hindering factor in their sustainable art-making process. Various impeding factors derived from the local cultural ecosystem have been identified within the Holistic Model, demonstrating that these factors are all intertwined and connected. Thus, analyzing and understanding one's local cultural ecosystem can provide keys to long-term and lasting impacts when a local authorities wish to support young artists for the future of local cultural environment.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
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• v.8 no.8
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• pp.1-9
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• 2018

Emotional Intelligence is the ability to recognize, facilitate, understand and control and utilize one's and other's emotions and has been researched extensively in last 20 years. Of the four domains of emotional intelligence, Emotional Regulation, the ability for one to manage and modify one's emotional reactions in order to achieve goal-directed outcomes, with its influence on authentic leadership and change oriented organizational citizenship behavior was researched by surveying 300 nurses at large metropolitan hospitals in B city in South Korea. Previous research demonstrated in relationship based and long term oriented cultures, such as Korea, Japan and Chinese cultures, ability to regulate emotions is critical component in successful social dynamics yet research the topic is minimal in Korea. Authentic leadership is a leader displaying sincerity and authentic behavior and through such, trust is gained in followers and collaboration is formed. Change oriented organizational citizenship behavior is a proactive behavior where the individual performs behaviors not included in his job functions voluntarily. The results indicate the three out of four sub domains of authentic leadership influenced positively to change oriented organizational citizenship behavior with the exception of balanced information processing. Moreover, Emotional Regulation partially mediated between authentic leadership and change oriented organizational citizenship behavior. Such results validated previous studies that indicated authentic leadership as possible antecedents of individual proactive behaviors and by examining authentic leadership and change oriented organizational citizenship behavior with emotional regulation as a mediator proved possibility as another potential antecedent of change oriented organizational citizenship behavior in hospital setting.