• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.6
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• pp.120-130
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• 2013

A study was conducted for the performance characteristics of methane taking recently the limelight in the world as a next-generation propellant, with the survey for state of the art in the development of methane/oxygen rocket engine being accompanied. Liquid methane as a rocket fuel has the favorable characteristics such as non-toxic, low cost, regenerative cooling capability, and potential for in-situ resource utilization (ISRU). The combination of liquid methane and liquid oxygen also provides the excellent performance including high specific impulse and low system mass. For these reasons, many researches have been actively carried out on the methane/oxygen engine, nevertheless, its technology readiness level is not that high enough just yet. Therefore, it is judged that it is the time to mitigate the technical gap with the space technology of advanced countries through a swift onset of the development of methane rocket engine.

• Journal of Practical Engineering Education
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• v.11 no.1
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• pp.87-103
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• 2019

The purpose of this study is to examine the factors affecting the intention of smart device internet usage from the perspective of lifelong learning of elderly people. Survey was conducted for understanding the factors affecting the internet usage intention of smart devices with 150 elderly people who visited the Gwangju Senior Technology Center (GSTC). The empirical results show that the perceived economic value and practical value of the elderly have a significant effect on the intention of utilizing the Internet of Smart Device. Although the moderating effect of the individual innovation of the elderly is not significant, Participation in social activities significantly moderated the relationship between perceived value and intention to use internet. In addition, the elderly expected that the quality of life would be improved via the use of smart devices.

• Pediatric Infection and Vaccine
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• v.28 no.2
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• pp.57-65
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• 2021

School closures during the coronavirus disease 2019 (COVID-19) pandemic have been outlined in studies from different disciplines, including economics, sociology, mathematical modeling, epidemiology, and public health. In this review, we discuss the implications of school closures in the context of the current COVID-19 pandemic. Modeling studies of the effects of school closures, largely derived from the pandemic influenza model, on severe acute respiratory syndrome coronavirus 2 produced conflicting results. Earlier studies assessed the risk of school reopening by modeling transmission across schools and communities; however, it remains unclear whether the risk is due to increased transmission in adults or children. The empirical findings of the impact of school closures on COVID-19 outbreaks suggest no clear effect, likely because of heterogeneity in community infection pressure, differences in school closure strategies, or the use of multiple interventions. The benefits of school closings are unclear and not readily quantifiable; however, they must be weighed against the potential high social costs, which can also negatively affect the health of this generation.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.310-321
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• 2021

The influence of regional economic growth on migration may also differ by age and generation age due to individual lifestyle. Therefore, this study analyzes an effects of changes in regional economic growth on migration between regions by age group. The result shows that the increase in the growth rate of the regional economy and job creation increased the net migration rate, regardless of age group. Second, it is found that the growth rate of the regional economy and job creation have a greater effect on the net migration rate for the youth population than for the middle-aged group. Third, it is found that the gap between regions in the level of individual income in the 25 to 29 years old and the level of land price fluctuations in the 40 to 64 years old affect the net migration rate. This implies that regional economic growth is still an important factor in the migration between regions, and has a great influence on the youth population.

• Journal of the Korean Vacuum Society
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• v.16 no.3
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• pp.161-166
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• 2007

Photovoltaic (PV) technology permits the transformation of solar light directly into electricity. For the last five years, the photovoltaic sector has experienced one of the highest growth rates worldwide (over 30% in 2006) and for the next 20 years, the average production growth rate is estimated to be between 27% and 34% annually. Currently the cost of electricity produced using photovoltaic technology is above that for traditional energy sources, but this is expected to fall with technological progress and more efficient production processes. A large scale production of solar grade silicon material of high purity could supply the world demand at a reasonably lower cost. A shift from crystalline silicon to thin film is expected in the future. The technical limit for the conversion efficiency is about 30%. It is assumed that in 2030 thin films will have a major market share (90%) and the share of crystalline cells will have decreased to 10%. Our research at Sungkyunkwan University of South Korea is confined to crystalline silicon solar cell technology. We aim to develop a technology for low cost production of high efficiency silicon solar cell. We have successfully fabricated silicon solar cells of efficiency more than 16% starting with multicrystalline wafers and that of efficiency more than 17% on single crystalline wafers with screen printing metallization. The process of transformation from the first generation to second generation solar cell should be geared up with the entry of new approaches but still silicon seems to remain as the major material for solar cells for many years to come. Local barriers to the implementation of this technology may also keep continuing up to year 2010 and by that time the cost of the solar cell generated power is expected to be 60 cent per watt. Photovoltaic source could establish itself as a clean and sustainable energy alternate to the ever depleting and polluting non-renewable energy resource.

• 한국노년학
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• v.31 no.3
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• pp.711-732
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• 2011

The purpose of this study is to understand the meaning and essence of aged life, which Korean elderly experience in real life and restructure them in the context of time and culture. In order to do so an in-depth interview was done with 15 elderlies over the age of 60 living in Hwaseong City, an urban-rural composite area in Gyeonggi Province where diverse elderlies could be found. In result, first, Korean elderly's understanding of aged life had physical, familial, economical, leisure, and social restoration aspects. Second, it was found that the degree of understanding about preparation for aging and preparedness is quite low. Third, as the gap between actual preparation for aging and aged life that elderly dreamed of became wider 'resentment on children', 'denial of reality', 'physical and economical change', and 'experience from prolongation of life-cycle' was found. Based on such results following suggestions could be made. First, the awareness of aged life and preparation for aging should be strengthened and there is a need for diverse educations aiming successful aged life. Second, elderly welfare policy and practical intervention with an integrated perspective based on the realm of life-cycle are demanded. Third, there is a need to strengthen the Aged Income Maintenance System for existing elder generation. Fourth, an intervention about adaptation and coping means of life event is needed. Lastly, there is a need to expand and carry out the aged life planning program for future elder generation.

• 한국노년학
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• v.31 no.3
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• pp.733-749
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• 2011

The purpose of this research are as follows. The first is to investigate the mediating effect of interpersonal skill on the relationship between the ability to use Internet and social activity among the 50's and 60's. The second is to compare 60's latent mean of core variables with 50's ones in terms of information gap. The data was Seoul welfare panel data made by Seoul welfare foundation in 2008 and the total subject was 941(50's=644, 60's=297). When it comes to the research methods, structured equation analysis for verifying the mediating effect and latent mean analysis for comparing the two groups were practiced. The results of this research are as follows. First of all, interpersonal skill did function as partial mediator. Second, according to the latent mean analysis, the group of 50's showed a more higher level of the ability to use Internet. On the other hand, the group of 60's revealed a more active social participation. In conclusion, Information educational programs should focus on Internet communication skill for enhancing social activities of the elderly and consider the differentiations among the elder generations.

• Journal of Korea Technology Innovation Society
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• v.10 no.4
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• pp.654-686
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• 2007

To estimate and analyze an interested science and technology level in any case requires three basic informations: (1) relative positions of our technology level, (2) other relevant technology level of the world best country holding the state of the art technology, and (3) its theoretical or practical maximum level within a certain period of time. Further, additional information from analyzing its respective rate of technology changes is necessary. It seems that most previous empirical or case studies on technology level have not considered third and fourth informations seriously, and thus critically have missed important findings from a dynamic point of view on the matter. A dynamic approach considering types of development processes and paths as well as current position needs an application of a concept of technology development stages and respective growth curves. This paper proposes a new method of approach and application by implementing relatively simple types of the growth curve(S-curve) such as logistic and Comports curves and applying estimation results of these curves to ten core technologies of the growth engines for the next future generation in Korea. The study implies that Korean science and technology level in general clearly gets higher as it approaches to a recent time of period, but relative technology gap from the world best in terms of catching-up period does not get better or narrower in case of at least part of the concerned technologies such as bio new drugs and human organs, and intelligence robots. The possibility does exist that some of our concerned technologies shooting for the next future generation may not come to the world highest level in the near future. The purpose of this study is to propose possibilities of catching-up, if any, by estimating its relevant type of growth pattern by way of measuring and analyzing technology level and by analyzing the technology development process through a position analysis. At this stage this study tries to introduce a new theoretical approach of estimating technology level and its application to existing case study results(data) from Korea Institute of Science and Technology Planning and Evaluation(KISTEP) and Korea Institute of Industrial Technology Evaluation and Planing(ITEP), for years of 2004 and 2006 respectively. The study has some limitations in terms of accuracy of measuring(estimating) a relevant growth curve to a particular technology, feasibility of applying estimated results, accessing and analyzing panel experts opinions. Hence, it is recommended that further study would follow soon enough to verify practical applicability and possible expansion of the study results.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.29 no.4
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• pp.416-421
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• 1984

Six soybean cultivars were used to study their seed development and germinability after flowering, in 1977 and 1978. The earlier varieties showed the faster seed development, but indeterminate types resulted in slower development. The earliest germinability was found in 15 to 25 days after flowering when dried with the pod shell. The germination of the seeds dried without pod shell, however, was inhibited significantly in early seed filling stages. Regular germinability of the Hill cultivar in a cold test was 40-45 days after flowering, or 10 to 15 days earlier than the physiological maturity.

• Journal of Korean Society of Disaster and Security
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• v.7 no.1
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• pp.35-42
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• 2014

This research has been shown the Research Plan for R&D Long-term Load-map Design in the Facility Disaster on response of the changing Disaster Environment, Showing the Strategy for the extending investment method of the technical development and related on that the advanced nation's technical level gap is minimized in the same area, Designing for the business' high-level, long-term load-map and the core driving strategy of the safety technology development business in the facility disaster, RFP Documentation on the core driving Business and the detailed driving Issue. This research has been resulted the three lists, trend analysis and Vision of the Technology Research Development (R&D) of the Safety Technology Area in domestic and foreign, the Responding Technology Predict and the Extended Research Strategy of the Next Generation Safety Technology in the facility Disaster, long-mid Term Road-Map of the Safety Technology in the facility Disaster, finally the Action Issue's RFP of the Safety Technology in the facility Disaster.