• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.883-889
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• 2021

The South Korean fishing industry is experiencing a rapid growth owing to an increase in its leisure-fishing population. Consequently, fishing boats weighing 9-10 [ton] have also been increasing. Current fishing boats operate their essential equipment by switching their engines with batteries to reduce the cost of gas and engine noise. However, stranding incidents have been increasingly recorded annually, in which boats fail to start owing to discharged batteries, and these incidents can lead to serious casualties. This study proposes the installation of a solar auxiliary power system to safeguard fishing boats, particularly those weighing between 9-10 [ton]. The feasibility of securing space for the solar auxiliary power of boats under consideration was verified. To examine the application of solar power, this study calculates the load necessary to operate it for fishing and models such a system using an electricity analysis program The modeled system, which applies the monthly horizontal solar insolation, validated the adoption of a solar auxiliary power in fishing boats.

• Korean Journal of Child Education & Care
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• v.18 no.4
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• pp.65-89
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• 2018

Objective: The purpose of this study is to analyze the science concepts and teaching and learning methods presented in the science education-related activities of the Nuri Curriculum teacher guidebooks for ages 3-5. Methods: The research data included 772 activities related to science education in the teachers' guidebook. The analysis of science concepts was based on physical science (force and motion, physical structure, electricity and magnetism, light and shadow, sound properties), chemistry (material properties, material reaction), life science (organizational structure, growth and change, heredity and evolution, animal plant and human relationships), earth science (earth system interaction, earth system structure, and universe), engineering (designed world, engineering design, engineering, technology and society) and ecology (environment preservation). Teaching and learning methods were analyzed according to the types of small and large group activities and of free play activities. Results: Science concepts were mainly presented in the fields of engineering, chemistry, and life science commonly among children aged 3-5, whereas the concepts of physical science were lowly presented in all ages. Science concepts appeared mainly in the daily subjects of 'animal plant and nature', 'life tools', 'environment and life', and 'spring, summer, autumn and winter'. As the teaching and learning method, free paly activities (science area, free outdoor selection activity, math and manipulative activity) were mostly used for the ages of 3 and 4, and small and large group activities (cooking, story sharing, music activity) were for the age of 5. Conclusion/Implications: It is necessary to select the level of science area and concept that can be taught according to the age of children and the timing of the teaching.

• Journal of the Korea Convergence Society
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• v.10 no.8
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• pp.181-193
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• 2019

The regional economy growth of Jeju has seen higher than national growth since 2011 by the establishment of Jeju Special Self-Governing Province and the increase of incoming population, but its economic growth has slowed after 2016. This study conducted the dynamic shift-share analysis using the production and employees of each industry from 2010 to 2016, targeting Jeju with many factors of regional economic change. In the results of empirical analysis, the regional economy of Jeju was not the industrial structure depending on the national growth, but the industrial structure by the competitiveness and industrial structure of Jeju region. The industries having positive(+) effects of industrial mix effect and competitive effect on the production and the number of employees were the electricity/gas/heavy equipments & waterworks, construction, accommodation & restaurants, and service industry. These industries have positive effects on the regional industry of Jeju. The above-mentioned industries are not only more likely to grow than other regions, but also to drive the local economy of Jeju. In order for these industries to continuously contribute to the regional economy of Jeju, it would be necessary to have the policy/institutional support in the long-term perspective.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.7
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• pp.2377-2398
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• 2021

In the recent modernized world, utilization of natural resources (renewable & non-renewable) is increasing drastically due to the sophisticated life style of the people. The over-consumption of non-renewable resources causes pollution which leads to global warming. Consequently, government agencies have been taking several initiatives to control the over-consumption of non-renewable natural resources and encourage the production of renewable energy resources. In this regard, we introduce an IoT powered integrated framework called as green home architecture (GHA) for green score calculation based on the usage of natural resources for household purpose. Green score is a credit point (i.e.,10 pts) of a family which can be calculated once in a month based on the utilization of energy, production of renewable energy and pollution caused. The green score can be improved by reducing the consumption of energy, generation of renewable energy and preventing the pollution. The main objective of GHA is to monitor the day-to-day usage of resources and calculate the green score using the proposed green score algorithm. This algorithm gives positive credits for economic consumption of resources and production of renewable energy and also it gives negative credits for pollution caused. Here, we recommend a green score based tax calculation system which gives tax exemption based on the green score value. This direct beneficiary model will appreciate and encourage the citizens to consume fewer natural resources and prevent pollution. Rather than simply giving subsidy, this proposed system allows monitoring the subsidy scheme periodically and encourages the proper working system with tax exemption rewards. Also, our GHA will be used to monitor all the household appliances, vehicles, wind mills, electricity meter, water re-treatment plant, pollution level to read the consumption/production in appropriate units by using the suitable sensors. These values will be stored in mass storage platform like cloud for the calculation of green score and also employed for billing purpose by the government agencies. This integrated platform can replace the manual billing and directly benefits the government.

• Journal of Korean Society of Disaster and Security
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• v.14 no.1
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• pp.9-21
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• 2021

Recently, the importance of eco-friendly power generation facility using renewable energy has newly appeared. Hydropower plant is a very important source of electricity generation and supply which is very important to secure safety because it is commonly connected with multi facility and operated on a large scale. In this study, a scenario-based analysis method was suggested to assess vulnerability of a penstock system caused by water hammer commonly occurred in the operation of hydropower plants. A hypothetical hydropower plant was used to demonstrate the applicability of a transient analysis model. In order to verify reliability of the model, the prediction of pressure behaviors were compared with the results of commercial model (SIMSEN) and measured data, then a real hydroelectric power plant was applied to develop all potential water hammer scenarios during the actual operation. The scenario-based simulation and vulnerability assessment for water hammer in the penstock system were performed with internal and external load conditions. The simulation results indicated that the vulnerability of a penstock system was varied with the operating conditions of hydropower facilities and significantly affected by load combination consisting of different load scenarios. The proposed numerical method could be an useful tool for the vulnerabilityty assessment of the hydropower plants due to water hammer.

• Journal of the Korea Convergence Society
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• v.12 no.8
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• pp.31-37
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• 2021

As the size of buildings increases due to urbanization due to the development of industry, the need to purify the air and maintain a comfortable indoor environment is also increasing. With the development of monitoring technology for refrigeration systems, it has become possible to manage the amount of electricity consumed in buildings. In particular, refrigeration systems account for about 40% of power consumption in commercial buildings. Therefore, in order to develop the refrigeration system failure diagnosis algorithm in this study, the purpose of this study was to understand the structure of the refrigeration system, collect and analyze data generated during the operation of the refrigeration system, and quickly detect and classify failure situations with various types and severity . In particular, in order to improve the classification accuracy of failure types that are difficult to classify, a three-step diagnosis and classification algorithm was developed and proposed. A model based on SVM and LGBM was presented as a classification model suitable for each stage after a number of experiments and hyper-parameter optimization process. In this study, the characteristics affecting failure were preserved as much as possible, and all failure types, including refrigerant-related failures, which had been difficult in previous studies, were derived with excellent results.

• Explosives and Blasting
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• v.39 no.4
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• pp.22-33
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• 2021

Recently, the frequent occurrence of ground subsidence in urban areas has caused increasing anxiety in residents and incurred significant social costs. Among the causes of ground subsidence, the rupture of old water and sewer pipes not only halts the operation of the buried pipes, but also leads to ground and water pollution problems. However, because most pipes are buried after construction and cannot be seen with the naked eye, the importance of maintenance has underestimated compared to other structures. In recent years, integrated physical exploration has been applied to the maintenance of underground pipes and structures. Currently, to investigate the internal conditions and vulnerable portions of the ground, consolidated physical surveys are executed. Consolidated physical surveys are analysis techniques that obtain various material data and add existing data using multiple physical surveys. Generally, in geotechnical engineering, consolidated physical surveys including electrical and surface wave surveys are adopted. However, it is difficult to investigate time-based changes in under ground using these surveys. In contrast, surveys using cosmic-ray muons have been used to scan the inner parts of nuclear reactors with penetration technology. Surveys using muons enable real-time observation without the influence of vibration or electricity. Such surveys have great potential for available technology because of their ability to investigate density distributions without requiring as much labor. In this paper, survey technologies using cosmic ray muons are introduced, and the possibilities of applying such technologies as new physical survey technologies for underground structures are suggested.

• Environmental and Resource Economics Review
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• v.30 no.4
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• pp.557-579
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• 2021

Collective energy is an intermediate stage in energy conversion and has a great influence on the power structure as a distributed power source. However, the problem of the collective energy business has recently emerged due to the worsening profitability of some collective energy operators. This study measured the technical efficiency of major operators through the estimation of the production efficiency of Korean collective energy operators, and based on this, we looked at ways to improve the profit structure of operators. After collecting detailed data from 16 collective energy operators between 2016 and 2019, the production efficiency of operators was estimated using the panel stochastic frontier model. As a result of the estimation, combined steam power operators showed the highest production efficiency and reverse CHP operators showed the lowest efficiency. Furthermore, as a result of examining the factors influencing profitability, it was confirmed that production efficiency has a positive effect on overall profitability. However, businesses with a high proportion of heat production, such as small district electricity operators, profitability was lower. This phenomenon is due to the structural limitations of the current heat sales market. Hence, the adjustment of the heat sales unit price is necessary to improve profitability of collective energy operators.

• The Journal of the Korea Contents Association
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• v.22 no.9
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• pp.85-94
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• 2022

In modern society, environmental and energy problems have caused to replace cars with environment friendly energy. Vehicles with internal combustion engine which use petroleum are one of the factors that influence global pollution due to environment problems such as fine dust and ozone layer destruction. In addition use of energies for automobile making resources to become depleted. To solve this limited oil energy problem by using other energy sources. To the problem using electric energy and green energy as alternative for a solution. Among environment friendly energies this paper studies the possibility of drive service for autonomous vehicles that self-charges using only solar energy and whether they can be used as pollution free and alternative energy for automobiles. Studies was researched based on published literature review, data from ministry of transportation and automobile companies. Also case of electric vehicle and prototype automobile using only solar energy and the theory of near future technologies. Many automakers are using electric cars as alternative energy. Also making efforts to use solar energy as an substitute energy source and as a way to supplement electricity. Results show that there is a potential on operating autonomous vehicle using only solar energy. Furthermore, it will be possible to use automobiles actively, also use and supply solar energy. This paper suggest the possibility of contributing to the future of the automotive industry.

• Journal of the Society of Disaster Information
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• v.18 no.3
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• pp.550-559
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• 2022

Purpose: Pipes are widely used as applied devices in many industrial fields such as machinery, electronics, electricity, and plants, and are also widely used in safety-related fields such as firefighting and chemistry. With the diversification of products, the importance of technology in the piping field is also increasing. In particular, when changing the existing copper pipe to stainless steel, it is necessary to evaluate safety and flow characteristics through structural analysis or flow analysis. Method: This study investigated the safety by flow analysis of the 6.35 inch socket model, which are integrated insert type connectors developed by a company, using CFD analysis technique. For CDF analysis, RAN model and LES model are used. Result: As results of the analysis, amplitude of the pressure fluctuation acting on the wall of the piping system is formed at a level of 3,780 Pa or less, which is a very small level of pressure compared with the operating pressure or design stress of the refrigerant piping. Conclusion: These results mean that the effect of vibration caused by turbulence on the structural safety of the pipe is negligible.