• 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.19 no.1
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• pp.623-633
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• 2019

This research investigated the mediating effects of communication skills in the relationship between perceived social support and school adjustment of high school students in the multicultural families, South Korea. The high school students from one to three degree in the school, who are joined the center for multicultural families in Kyeonggi-do province, were participated in the survey for this research. Total 110 were analysed using SPSS version 23.0, and used a correlation and regression analyses, proposed by Baron and Kenny(1986), to estimate the relationships between research variables. The results were as follows: First, perceived social support, communication skills and school adjustment were significant associated each other, and had positive correlations. Secondly, communication skilsl of multicultural families' high school students in South Korea had partial mediating effects on the relationship between perceived social support and school adjustment. Based on these findings, the limitations and implications of this research were discussed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.7
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• pp.870-874
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• 2018

In the worst maritime accidents, people should abandon ship, but ship structures are narrow and complex and operation takes place on rough seas, so escape is not easy. In particular, passengers on cruise ships are untrained and varied, making evacuation prospects worse. In such a case, the evacuation management of the crew plays a very important role. If a rescuer enters a ship at distress and conducts rescue activities, which zones represent the most effective entry should be examined. Generally, crew and rescuers take the shortest route, but if an accident occurs along the shortest route, it is necessary to select the second-best alternative. To solve this situation, this study aims to calculate evacuation routes using Q-Learning of Reinforcement Learning, which is a machine learning technique. Reinforcement learning is one of the most important functions of artificial intelligence and is currently used in many fields. Most evacuation analysis programs developed so far use the shortest path search method. For this reason, this study explored optimal paths using reinforcement learning. In the future, machine learning techniques will be applicable to various marine-related industries for such purposes as the selection of optimal routes for autonomous vessels and risk avoidance.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.4
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• pp.378-383
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• 2018

The goal of this study was to examine the growth and yield according to planting density in wide-row drill seeding cultivation suitable for mechanized harvesting. We evaluated effects depending on planting densities [row spacing (30, 40, 50, and 60 cm) and plant spacing (10, 15, and 20 cm)] and cultivars ('Hongeon' and 'Arari') on growth and yield of Adzuki Beans (Vigna angularis (Willd.) Ohwi Ohashi). When row spacing decreased, the stem length increased in 'Arari' but decreased in 'Hongeon.' The stem diameter and number of branches in both the cultivars decreased with a decrease in row spacing. The pod height increased with lower planting densities. The greatest height values recorded in 'Hongeon' and 'Arari' were 5.0 cm and 8.8 cm in $30{\times}10cm$ and $50{\times}10cm$ treatments, respectively. The number of pods and number of seeds in both cultivars tended to increase with a decrease in planting density. On the other hand, in 100-seed weight, there was a difference in planting density in 'Hongeon', but no difference in 'Arari'. The highest yield was at the planting density of $40{\times}15cm$ in both 'Hongeon' and 'Arari', $285kg{\cdot}10a^{-1}$ and $374kg{\cdot}10a^{-1}$.

• Journal of The Korean Association For Science Education
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• v.38 no.6
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• pp.781-792
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• 2018

In modern society, as technology develops and industry diversifies, students can choose from a variety of career paths. Since science, technology, engineering, and mathematics require a longer education and experience than other fields, it is important to design science education policies based on the competencies required for science, technology, engineering, and mathematics (STEM) occupations. This study explores the definition of science and technology manpower and STEM occupations and identifies core competencies of STEM occupations using standard job information operated and maintained by the US Department of Labor ($O^*NET$). We specially analyzed ratings of the importance of skills (35 ratings), knowledge (33 ratings), and work activities (41 ratings) conducting descriptive analysis and principal component analysis (PCA). As a result, core competencies of STEM occupations consist of STEM problem-solving competency, Management competency, Technical competency, Social service competency, Teaching competency, Design competency, Bio-chemistry competency, and Public service competency, which accounts for 70% of the total variance. This study can be a reference for setting the curriculum and educational goals in secondary and college education by showing the diversity of science and technology occupations and the competencies required for STEM occupations.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.4
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• pp.384-389
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• 2018

Cultivation techniques of proso millet (Panicum miliaceum L.) and foxtail millet (Setaria italica L.), such as sowing, weeding, and harvesting, are often not properly utilized, resulting in low productivity rates. The goal of this study was to develop cultivation techniques to increase millet productivity rates and reduce labor inputs. We evaluated the effects of different machine sowing methods compared with manual sowing methods from 2014 to 2016. The three machine sowing methods were dibbling, drilling, and broadcasting. Compared with manual sowing, the broadcasting method decreased labor times by 16.07 and $14.23hr10a^{-1}$ for proso and foxtail millets, respectively. Proso millet showed greater culm lengths at 138 and 125 cm with the broadcasting method for two years, whereas foxtail millet after three years had greater culm lengths from both the drilling and broadcasting methods. Both crops exhibited the thickest culm stems in the $3^{rd}$ year. The greatest number of seeds of the panicle were from the manual sowing method in both crops. Compared with manual sowing, broadcasting increased grain yields by 15-35% and 9.1-28% for proso and foxtail millets, respectively. Therefore, we suggest that the application of broadcasting in mechanical sowing will increase labor efficiency and yields of proso and foxtail millets.

• International Area Studies Review
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• v.20 no.2
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• pp.3-23
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• 2016

In this study, we used actual proof analysis, based on SVAR model according to economy theory, to observe the impact of actual and financial market of Korea, Japan, and China that have adopted quantitative easing export based strategy of growth, an unconventional monetary policy of the U.S. As a result of estimation, it appears that real effective exchange rate rise shock of Korea, Japan, and China against U.S. dollar has a negative influence on current account and index of industrial product, which are real economy. It can be implied that the result is driven from the fact that strong home currency of Korea, Japan, and China decreases price competitiveness of exports, causing negative influence on real economy. The real effective exchange rate shock against U.S. dollar appeared to decrease national bond rate of Korea and Japan, while increasing that of China. In instances of Korea and Japan, it is implied that national bond rate decreases as foreigner investment funds flow in, considering foreign-exchange profit through advanced financial market with high opening extent. On the other hand, because there are strong regulation on opening extent of Chinese financial markets, the influence seems to be greater for domestic policy, rather than a foreign influence. Lastly, Korea showed a more dramatic variable reaction to exchange rate shock compared to Japan or China. It is implied from the result that Korea is relatively more susceptible and fragile in regards of international status of economic size and currency.

• 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.

• The Journal of the Korea Contents Association
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• v.18 no.11
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• pp.462-474
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• 2018

The development of bio-sensing technology made it easy to collect various biometric information that was only available in large medical devices. The miniaturization of sensors makes it simple to carry out various health checkups that It did in person to the hospital by improving the portability of diagnostic devices. It is able to combine sensors into portable devices such as Smartphones, apply advanced Internet of Things (IOT) technology, and create new form factors for medical devices such as ultra-small modules that can be inserted or attached to their bodies. The results can be checked immediately through portable information devices such as smart phones. Although commercialization is still slow in Korea, new technologies are being applied in various ways in countries such as the United States that have granted remote medical services. Medical demand, supply and cost in South Korea are growing ahead of a super-aged society. Under these circumstances, attention is focusing on whether smart healthcare, a new concept, can complement the existing medical system. This study identifies the technology trends associated with smart health care and categorizes various healthcare products in the UX design aspects. In addition, the UX design approach and guidelines for applying smart healthcare technologies to the elderly, the intended users, are presented. This research will provide a reference to a new social issue, the UX-design approach to solving the problems of the aged society.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.64 no.1
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• pp.33-39
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• 2019

The goal of this study was to investigate how the characteristics of growth and yield are affected by various planting densities in wide-row drill seeding cultivation suitable for mechanized harvesting. Two cultivars ('Hwanggeum' and 'Leebackchal') of proso millet (Panicum miliaceum L.) were planted at varying planting densities [row spacing (20, 30, and 50 cm) and plant spacing (3, 5, 10, and 15 cm)]. The culm length was highest at the planting density of $50{\times}3cm$ and $50{\times}5cm$ for 'Hwanggeum' and $20{\times}3cm$ for 'Leebackchal'. The culm diameter became thinner as the planting density increased. The number of tillering and panicle length showed the same tendency to increase in quantity or length as planting density decreased and was highest at $50{\times}15cm$ when the planting density was lowest. The number of seeds per individual increased as planting density decreased. The thousand grain weight showed no significant differences among treatment plots. The greatest yield of 'Hwanggeum' was obtained at a planting density of $50{\times}3cm$ ($314.9kg{\cdot}10a^{-1}$) and that of 'Leebackchal' was obtained at $50{\times}3cm$ and $50{\times}5cm$ ($358-356kg{\cdot}10a^{-1}$).