• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.6
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• pp.629-636
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• 2022

Domestic eco-friendly vehicles currently account for 5.8% of the total registered vehicles in Korea. Hydrogen vehicles, one of the representative eco-friendly vehicles, have grown rapidly as they have been expanded to the market based on the government's policy to boost the hydrogen industry. Therefore, it is time to expand the safety review of hydrogen vehicles in various directions according to the increase in supply. In this study, the effect of internal heat damage was analyzed when a jet flame was generated by a hydrogen car in a road tunnel. It was simulated using Fluent, and the amount of jet flame injection was selected in consideration of the hydrogen tank capacity of commercial hydrogen vehicles for road tunnels. In addition, the study was conducted with the direction of the jet flame and the nozzle distance from the tunnel wall as variables. From the results, when the jet flame erupted in the road tunnel, high radiant heat emission of more than 20 kW/m² was generated in most areas within ±5 m in the longitudinal direction based on the vehicle (spray nozzle) and 5 to 7 m in the lateral direction based on the adjacent tunnel wall.

• 한국노년학
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• v.38 no.2
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• pp.291-308
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• 2018

The purpose of this study is to analyze the factors influencing financial preparedness for retirement of the middle-aged North Korean defectors (resettling in South Korea) using concepts of 'financial literacy' and 'financial inclusion'. Those questioned were 100 North Korean defectors of 40-60 years-old residing in Seoul and Gyeonggi-do Province selected by convenience sampling, one of the non-probability sampling. Path analysis is used as a main analysis method. The results of the study show a direct effect in which increased financial literacy resulted in better financial preparedness for retirement among middle-aged North Korean defectors at a statistically significant level. In addition, by boost-trapping method, financial inclusion has its mediating effect on the relationship between financial literacy and financial preparedness for retirement. However, this study shows that influence of financial literacy on financial preparedness for retirement is different across economic statues. The mediating effect of financial inclusion on the relationship between financial literacy and financial preparedness is statistically significant only for the low-income group. Meanwhile, for the above average income group, financial literacy has a direct effect on the financial preparedness after retirement at a statistically significant level. Based on these results, this study suggests practical and policy implementation such as necessity of customized financial education suited to their economic status, development of financial instruments for retirement, introduction of financial social workers to prepare stable old age of North Korean defectors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.8
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• pp.164-173
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• 2019

The purpose of this research was to introduce a network analysis method for analyzing technology trends in the aerospace industry at the Farnborough International Airshow (FIA), one of the world's three major airshows. Civil and defense companies and government and military officials from 112 countries and 1,500 agencies convened at FIA 2018 to share and explore recent trends in the aerospace industry. We studied aerospace technologies from 45 countries, 1,108 exhibiters, and 223 technology categories via centrality analysis. The results from the network analysis showed that machining is the center of aerospace technology. However, there were quite different tendencies, depending on the region and country. The centers of aerospace technology are machining in Europe and the United Kingdom, aircraft components in Asia, and engine components/controls in the United States. In Korea, no one key technology was recognized, due to the country's small attendance. We hope this research will be conducive to aerospace technology-and-research planning, and that it will be an appropriate tool to help domestic manufacturers boost their exports.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.179-184
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• 2019

In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power.

• The Journal of the Korea Contents Association
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• v.18 no.12
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• pp.140-149
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• 2018

Along with the recent increase in national income, social phenomena such as aging due to a decrease in population and an increase in single households are observed. There are also an increasing number of households raising pets in proportion to aging households and the increase in the number of single households, most of which use animal companions to overcome loneliness and boost domestic vitality. As more and more people consider pets as family members, the size of the domestic pet market is also growing. The growing number of pets in older households and single households is not properly managed by care such as food meals and exercise management for pets. It is necessary to research and develop robots that can monitor animal companions remotely, feed a certain amount of food at regular intervals, and manage their health through exercise. Among pet companions, dog selection is the highest. Therefore, this study identified robot research on driving methods, examples of existing pet care systems, and researched pet care robots using obstacle avoidance algorithms. In order to use the snack pay behavior and obstacle avoidance algorithm of the pet animals by applying IoT and we .oPI technology, it is able to use ultrasonic sensors on the front and has four infrared sensors on the back. However, this study does not reflect the characteristics of other pet animals as a study on pet care robots, and it requires continuous observation and testing.

• Korean Journal of Child Education & Care
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• v.18 no.4
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• pp.27-38
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• 2018

Objective: The purpose of this study is to investigate the effects of childcare teachers' teacher efficacy, psychological burnout and the practice of respecting rights for infants. Methods: For this study, questionnaires were distributed to 398 childcare teachers in the cities of I and S. The collected data were analyzed by descriptive statistic, multiple regression and Cronbach's ${\alpha}$ for reliability by SPSS-WIN computer program. Results: The results yielded some interesting results. First, childcare teachers were shown to have higher respecting rights for infants but just average teacher efficacy rates. Secondly, the study showed a positive correlation between the practice of respecting rights for infants and childcare teachers' teacher efficacy. However, there was a negative correlation between the practice of respecting rights for infants and psychological burnout. There was also a negative correlation between the practice of respecting rights for infants and childcare teachers' teacher efficacy. Third, the higher the childcare teachers' teacher efficacy of childcare teachers, the more positive influences existed in the practice of respecting rights for infants. It also showed that the lower the degree of psychological burnout, there was a negative impact on the practice of respecting rights for infants. Conclusion/Implications: The results of this study suggest that a support plan is needed to boost childcare teachers' teacher efficacy, and to lower the psychological burnout of childcare teachers with regards to the practice of respecting rights for infants.

• Journal of Technology Innovation
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• v.27 no.1
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• pp.1-43
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• 2019

The significance of SMEs (small and medium-sized enterprises) is gradually highlighted as we have entered the age of "New Normal." The South Korean government support these enterprises to boost economic growth and create more jobs. It also releases numerous policies such as national R&D projects and expanding tax incentive services particularly aiming at promoting dramatic investment in R&D and technological innovation. There is a sharp contrast regarding the efficiency of direct or indirect supports for encouraging R&D investment launched by SMEs depending on researchers. However, there has been little attempt to explore the optimal combination of two policy tools. Amid promoting affiliated governmental departments in charge of SMEs policies and constantly growing R&D investment, it is an appropriate time to discuss the medium and long-term direction for the optimal policy mix of direct and indirect supports. In this study, the author obtained 32 relevant studies published earlier in the domestic journals, explored literatures more systematically, and further conducted a meta-analysis. It is dedicated to summarizing relevant controversies and organizes them empirically beyond merely verifying whether policy support stimulates private R&D investment by SMEs. The meta-analysis showed that it would be effective to support as tax for large enterprises, while subsidiary support for SMEs. However, indirect support needs to be progressively increased as direct support primarily accounts for the entire R&D support for South Korean SMEs.

• Journal of Korea Port Economic Association
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• v.35 no.1
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• pp.139-162
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• 2019

In the case of Korea, policy support for shipping companies is limited, and the financial support should address the scale and period of support. Comprehensive measures are needed to boost the chances of reviving the industry. In order to secure competitiveness, the shipping companies need to make continuous efforts, prepare for the future by strengthening environmental regulations, and ensure that they have the ability to be flexible in their responses. The shipbuilding industry witnessed some improvement last year amid severe recession, but reforms are needed to address external and internal structural problems; further, to gain the characteristics of future leading industries, it is necessary to secure core technologies, as well as differentiated and specialized industrial competitiveness among rival countries through joint government intervention and joint R&D investment. Taking these steps will ensure that it has environment-friendly vessels and economic shipbuilding capabilities. The competitiveness of Busan Port should enable the utilization of the geopolitical characteristics of East Asia and contribute to: regional economic revitalization; development of its status as hub port; and securing the position of developed countries in East Asian logistics. For this purpose, it is necessary to establish a strategy to: expand the usability of shipowners/carriers; improve the quality of port operations; improve the portability of the smart system; expand the port of mega-ocean carriers; speed up port operations; and create low-cost ports. The establishment of a network of four countries will also require long-term global linkages. For example, there is a need to establish a logistics network between Eurasia and the European region, which will use the Russian Land Bridge System, as well as that of China.

• Korean Journal of Child Education & Care
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• v.19 no.3
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• pp.47-56
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• 2019

Objective: The purpose of this study is to investigate the relations between the childcare teacher's intrapersonal intelligence and the childcare of infant's right respects, and examine the mediating effect of the childcare teacher's professionality in the relationship between them. Methods: For this study, questionnaires were distributed to 351 childcare teachers in the city of J. The collected date were analyzed by descriptive statistic, multiple regression and Cronbach's ${\alpha}$ for reliability by SPSS 24.0 program. Results: The results are as following. First, the childcare teacher's intrapersonal intelligence, the childcare of infant's right respects, professionality showed a significant positive relation. Second, the partial mediating effect of the professionality in the relationship between the childcare teacher's intrapersonal intelligence and the childcare of infant's right respects. It was confirmed that the interpersonal intelligence had a positive effect on the childcare of infant's right respects and the professionality a mediating variable. Conclusion/Implications: The results of this study suggest that a support plan is needed to boost childcare teacher's intrapersonal intelligence and the professionality with regards to the childcare of infant's right.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.12 no.4
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• pp.456-465
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• 2019

PHEV(Plug in Hybrid Electric Vehicle) and BEV(Battery Electric Vehicle) equip high voltage batteries to drive motor and vehicle electric system. Those vehicle require OBC(On-Board Charger) for charging batteries and LDC(Low DC/DC Converter) for converting from high voltage to low voltage. Since the charger and the converter actually separate each other in electrical vehicles, there is a margin to reduce the vehicle weight and area of installation by integration two systems. This paper studies a 1.5kW LDC converter that can be integrated into an OBC using an isolated current-fed converter by simplifying the design of LDC transformers. The proposed LDC can control the final output voltage of the LDC by using a fixed arbitrary output voltage of the bidirectional buck-boost converter, so that Compared to the existing OBC-LDC integrated system, it has the advantage of simplifying the transformer design considering the battery voltage range, converter duty ratio and OBC output turn ratio. Prototype of the proposed LDC was made to confirm normal operation at 200V ~ 400V input voltage and maximum efficiency of 91.885% was achieved at rated load condition. In addition, the OBC-LDC integrated system achieved a volume of about 6.51L and reduced the space by 15.6% compared to the existing independent system.