• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.10
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• pp.1471-1476
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• 2012

A study on the dielectric characteristics of the Glass Fiber Reinforced Plastic (GFRP) is important for designing a reliable high voltage superconducting machines such as transmission superconducting fault current limiters, superconducting cables, and superconducting transformers. In this paper, dielectric experiments of the GFRP under lightning impulse voltage are conducted in liquid nitrogen($LN_2$) according to various experimental conditions such as the thicknesses of the GFRP, the diameters of electrode systems and the pressures. The dielectric characteristics of the GFRP are analyzed by using a Finite Elements Method(FEM) according to various field utilization factors. It has been reported that the electrical insulation design of the GFRP would be conducted by considering the mean electric field intensity($E_{mean}$) distributed inside the GFRP. In this study, it is found that the dielectric performance of the GFRP could be explained by not only $E_{mean}$ but also the maximum electric field intensity ($E_{max}$). Finally, the empirical formulae of the GFRP to estimate an electrical breakdown voltage at sparkover under the lightning impulse condition are deduced. It is expected that the presented experimental results in this paper are helpful to design electrically reliable high voltage superconducting machines using the GFRP as an insulation material.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.23 no.5
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• pp.99-112
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• 2020

This study aims to propose biotope field datasheet and biotope type classification based on habitat-based by analyzing the German biotope system. The German system began in 1976 and has established a habitat-based national biotope classification system. On the other hand, Korea institutionalized in 2018 to build a classification system based on land use and land cover, which is a classification system that does not fully reflect ecosystem in Korea. Germany operates 44 biotope classification systems and 40 biotope field datasheet. Korea uses a single biotope field datasheet regardless of the biotope type. This classification system may not reflect the characteristics of Korea's biotope ecological habitat. The biotope classification system of Korea was proposed by dividing it into five categories: mountain ecology, freshwater ecology, land ecology, coastal ecology, and development area to reflect ecosystem habitat. The biotope type was designed as a system of large-classification-middle-small classification and subdivided into medium-classification and subdivided in each biotope system. The major classifications were classified into 44 categories according to the mountainous biotope(11), freshwater biotope(8), terrestrial biotope (12), coastal biotope(6), and development biotope(7). Unlike Germany, Korea's biotope field datasheet was proposed in five ways according to the classification of major ecosystem types. The results of this study are expected to contribute to the policy suggestion and the utilization of ecosystem conservation because the biotope classification system is classified to reflect the characteristics of ecosystem habitats.

• Journal of Power System Engineering
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• v.20 no.1
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• pp.5-10
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• 2016

Swing check valve is opened when the flow direction is forward, when the flow is reversed, the valve is automatically closed by back pressure. In this study, the internal flow field analysis of the valve was conducted by Fluent. The working fluid used in the study, using liquefied methane $-165^{\circ}C$ (CH4) and velocity field, pressure field, pressure drop coefficient were simulated by varying separately the opening divergence into four intervals from 0 to 100%. The approximate research result are as follow : When the opening divergence is smaller, it appears high pressure on the upstream side, this value is relaxed when the opening divergence is large. Flow rate coefficient of the valve shows a larger value as the degree of opening becomes larger, confirming that the check valve used in the study is in the effective flow rate counting range.

• Environmental Engineering Research
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• v.18 no.3
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• pp.117-121
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• 2013

For underpasses in Yeongjong Sky City business district, the guided drainage system, as a buoyancy prevention system has been designed, and is under construction. This paper investigates the safety of the guided drainage system for underpass structures being constructed in Yeongjong Sky City business district. This paper also calculates the amount of outflowing groundwater generated by the guided drainage system, and proposes alternative usages of the water. In order to investigate safety and field applicability of the guided drainage system for underpasses, characteristics of the surface flow for the area of interest have been analyzed, and the flow change of groundwater following the underpass structure construction has been evaluated using the 3-dimensional groundwater program MODFLOW. The influence of ground water on safety of the underpass structures has been calculated by FLAC2D analysis. For alternative usages for the outflowing groundwater generated by the guided drainage system, utilization methods of the outflowing groundwater in national and international resources have been researched. The amount of an outflowing groundwater to be generated in the area of interest has been analyzed, and efficient potential usages of this groundwater have been researched. When guided drainage technique is applied, the change in flow of groundwater must be evaluated and considered as safety factor relating to the buoyancy of the structure. As a result, safety factor demonstrated more than 1.2, meaning that the underpass structure is safe. The amount of subsoil drain generated by the guided drainage system was also analyzed. The quality and amount of water satisfied the standards and volume requirements, so as to make it applicable for a number of uses, such as X, Y, and Z, and should prove to be a valuable resource as the circumstances of the neighboring area change over time. These resources can be used as basic data for future urban water circulation studies, as well as generating research of alternative water usages.

• Journal of Korea Multimedia Society
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• v.14 no.3
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• pp.471-479
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• 2011

The world has witnessed a phenomenal growth in information and communication technologies (ICT). The development of new broadband communication services convergence of telecommunication with computers and recent developments in the field of communication protocol have fostered challenges as well as offerings in the wide-ranging use of ICT to support the creation of dynamic and interactive teaching and learning environment. By emergence of ICT, most of education and training institutions are struggling to integrate ICT and education and training systems. It is so important to apply proper delivery systems for utilization of the computerized teaching and learning contents in the classrooms. It will be a preliminary activity for building open and flexible distance teaching and learning systems in developing countries. In this paper, we would like to suggest and recommend the proper delivery systems for utilization of the computerized teaching and learning contents in the classrooms for education sector reform in developing countries.

• Journal of Korean Society of Rural Planning
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• v.5 no.2 s.10
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• pp.1-13
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• 1999

Packing house is the regional center in which packing, sorting, storage, and selling of harvested fruits are taken care of all together. It is located at the producing centers, and commercializes their apples. Apple grading policies of chief producing centers should concentrate on enhancing functions and roles of its local packing house. Consequently new packing house policies for enacting individual grading standards at national and local levels should be developed. This study is to develop Korea packing house on the basis of field survey in New York State. Increasing the utilization of packing house is the main key to the success of apple grading project. Therefore, effective arrangement and utilization of sorting facilities should be evaluated and new system which enables apple farms, local cooperatives, and corporations to joint-utilize packing house must to be established.

• The Transactions of the Korean Institute of Power Electronics
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• v.4 no.5
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• pp.474-482
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• 1999

In this paper, a new field weakening algorithm which maximizes the output torque not only in steady state b but also in transient state is proposed. Considering both voltage and current limit of system, analytic solutions f for optimal torque utilization in field weakening region I and region II are obtained. This algorithm finds optimal currents considering dynamic vol떠ge limit based on flux and speed. So the maximum usage of stator v voltage even in transient state results in the maximum torque and fast response time. Simulation and e experimental results show the effectiveness of the proposed field weakening scheme.

• International Journal of Advanced Culture Technology
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• v.9 no.4
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• pp.102-109
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• 2021

Since the 4th Industrial Revolution is implemented based on superintelligence, new insights must be provided through convergence studies with other fields to find optimal solutions to create new ideas. In this paper, we intende to present improvement measures for probability and statistical education, which is an athlete's subject on data analysis and processing in the ICT(Information & Communication Technologies) field in the era of superintelligence of the 4th industrial revolution. This paper aims to strengthen competitiveness through early development and commercialization of new technologies by presenting probabilities and statistical curriculums that require linkage in the ICT field. Second, it is necessary to present an educational system diagram linking probabilities and statistics in the ICT field to prepare a mid- to long-term response strategy for ICT education in response to innovative changes. Third, through a survey, we intend to present an effective educational operation plan linking probability and statistics to ICT major subjects by analyzing the perception of probability, statistical importance, and utilization of majors in this field.

• Smart Media Journal
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• v.9 no.2
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• pp.99-109
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• 2020

This paper proposes a platform construction plan for the use of spectrum big data, collects and analyzes the big data in the radio wave field, establishes a linkage plan, and presents a support system scheme for linking and using the spectrum and public sector big data. It presented a plan to build a big data platform in connection with the spectrum public sector. In a situation where there is a lack of a support system for systematic analysis and utilization of big data in the field of radio waves, by establishing a platform construction plan for the use of big data by radio-related industries, the preemptive response to realize the 4th Industrial Revolution and the status and state of the domestic radio field. The company intends to contribute to enhancing the convenience of users of the big data platform in the public sector by securing the innovation growth engine of the company and contributing to the fair competition of the radio wave industry and the improvement of service quality. In addition, it intends to contribute to raising the social awareness of the value of spectrum management data utilization and establishing a collaboration system that uses spectrum big data through joint use of the platform.

• Journal of Soil and Groundwater Environment
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• v.28 no.spc
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• pp.18-39
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• 2023

Rapid development of geophysical exploration and hydrogeologic monitoring techniques has yielded remarkable increase of datasets related to groundwater systems. Increased number of datasets contribute to understanding of general aquifer characteristics such as groundwater yield and flow, but understanding of complex heterogenous aquifers system is still a challenging task. Recently, applications of data science technique have become popular in the fields of geophysical explorations and monitoring, and such attempts are also extended in the groundwater field. This work reviewed current status and advancement in utilization of data science in groundwater field. The application of data science techniques facilitates effective and realistic analyses of aquifer system, and allows accurate prediction of aquifer system change in response to extreme climate events. Due to such benefits, data science techniques have become an effective tool to establish more sustainable groundwater management systems. It is expected that the techniques will further strengthen the theoretical framework in groundwater management to cope with upcoming challenges and limitations.