• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.111-116
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• 2022

The causes of motor burnout include overload, phase loss, restraint, interlayer short circuit, winding ground fault, instantaneous overvoltage, and the rotor contacting the stator, leading to insulation breakdown, leading to breakdown or electrical accidents. Therefore, equipment failure causes not only loss due to cost required for equipment maintenance/repair, but also huge economic loss due to productivity decrease due to process stop because the process itself including the motor is stopped. The current level of technology for diagnosing motor failures uses vibration, heat, and power analysis methods, but there is a limit to analyzing the problems only after a considerable amount of time has passed according to the failure. Therefore, in this paper, a device and algorithm for measuring insulation resistance using DC AMP signal was applied to an industrial motor to solve this problem. And by following the insulation resistance state value, we propose a diagnosis of deterioration and failure of the motor that cannot be solved by the existing method.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1113-1120
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• 2022

In this paper, a communication methodology for the digital FRTU(: Feeder Remote Terminal Unit) required by the smart grid distribution system was studied. The digital FRTU consists of a fault handling unit and a communication unit. The fault handling unit transmits fault information to the communication unit in case of a failure, and the communication unit is designed to autonomously determine the fault section through two-way communication between surrounding digital FRTUs. For performance verification, a performance verification system consisting of 3 line sections based on 3 digital FRTUs was constructed to enable fault simulation for various failure scenarios. Various fault cases including one phase ground fault, line-to-line short-circuit fault, and three-phase short-circuit fault were experimentally simulated on the established performance verification system, and the validity of the developed methodology was confirmed by proving the accurate fault section inference results for each fault simulation case.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.459-466
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• 2022

Switching surges are a common type of phenomenon that occur on any sort of power system network. These are more pronounced on long transmission lines and in high voltage converter stations. At AC/DC hybrid transmission lines, the insulation coordination of such lines is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and AC/DC converter station. The power system structure consist of AC/DC hybrid transmission lines which is combination of AC 765kV and ±500kV HVDC 1 bipole system for contingency analysis. The power system under study and its components are simulated using EMTDC software package, the effects of the various AC/DC mixing power lines are reviewed. The developed models of EMTDC conversion lines based on combination of AC/DC system are simulated and the characteristics of switching surge over-voltage from its results are discussed.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.5
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• pp.817-826
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• 2023

In this paper, a fault determination methodology based on an artificial neural network was proposed to protect the system from faults on the lines in the smart grid distribution system. In the proposed methodology, first, it was designed to determine whether there is a low impedance line fault (LIF) based on the magnitude of the current RMS value, and if it is determined to be a normal current, it was designed to determine whether a high impedance ground fault (HIF) is present using Normal/HIF classifier based on artificial neural network. Among repetitive DSP module-based algorithm verification tests, the normal/HIF classifier recognized the current waveform as normal and did not show reclosing operation for the cases of normal state current waveform simulation test where the RMS value was smaller than the minimum operating current value. On the other hand, for the cases of LIF where RMS value is greater than the minimum operating current value, the validity of the proposed methodology could be confirmed by immediately recognizing it as a fault state and showing reclosing operation according to the prescribed procedure.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.652-661
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• 2020

Recently, the Korean government developed the RE3020 (renewable energy) policy to overcome environmental problems, such as fine dust, climate change, and large-scale PV systems interconnected with a distribution system. When a large-scale PV system is interconnected in the distribution system, however, a malfunction can occur, and the protection devices may not be operated because of the dividing effect depending on the magnitude and direction of fault current as well as connection types and location of the PV system. Therefore, this paper proposes a search algorithm for the malfunction pattern of protection devices based on various scenarios, when large-scale PV systems are operated and interconnected in a distribution system. This paper presents a malfunction mechanism of protection devices according to the installation locations of recloser (R/C). Furthermore, the modeling of a distribution system with large-scale PV systems was performed using Off-DAS S/W, and the malfunction patterns of protection devices were analyzed based on a range of scenarios. From the simulation results with the proposed model and algorithm for searching for protection devices, it was confirmed that they are useful and effective in identifying a malfunction phenomenon depending on the installation location of the R/C and connection type of PV system.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.30 no.1
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• pp.76-89
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• 2012

This study aimed at carrying out a semantic interpretation of the core Design language that seemed to influence deeply in the creation of the ChwuiseokJeong wonlim of Gochang. Especially, this paper aimed at inferring how the spiritual culture of seclusion of the 16th century influenced the creation of the wonlim by understanding the metaphor and symbolism by grasping the transmission meaning and reception meaning of the creators and the people concerned with keywords like Eunil(隱逸: seclusion), Chwuiseok(醉石), and Chilseongam(七星巖). 'Building up a wall' was intentionally carried out in order to represent 'Seven Stars(The Big Dipper)' inside of the wonlim. This is a kind of two-dimensional 'enframement', and a result of active creation of a meaningful landscape. From Chilseongam that was created by assembling, we presumed that Kyung-Hee Kim, Nohgye(蘆溪), the creator showed the recognition and thoughts of astronomy as a Confucian scholar that the ChwuiseokJeong Wonlim where he secluded is the center of the universe. The interpretation of words in Nohgyezip, an anthology, showed that the articles and writtings of Nohgye, his decsendants, and the people of ChwuiseokJeong included alcohols, Chwuiseok, Yeon-Myung Do, and Yuli(栗里) where Do secluded; this means that Nohgye ranked himself with Do because Nohgye also lived in peace by drinking alcohols and enjoying nature like Do did. 'Drinking' was what expressed the mind of Nohgye who wanted to be free and have the joy of enjoying mountains, water, and their landscape like Do did. In other words, 'Drinking' is the symbol of freedom that makes him forget himself and equate himself with nature. These are the representation, imitation, and mimesis of respecting Yeon-Myung Do. As the alegory of 'speaking something with other things' suggested, it is possible to read 'Chwuiseok', came from the story of Yeon-Myung Do, in multiple ways; it superficially points out 'a rock on which he laid when he was drinking', but it also can be interpreted as 'an object' that made him forget his personal troubles. In addition, it means freewill protecting unselfish mind with the spiritual aberration of drinking, 'Chwui(醉)', mentally; also, it can be interpreted metaphorically and broadly as a tool that makes Nohgye reach to the state of nature by the satisfied mind of Yeon-Myung Do. 'Chwuiseok' was a design language that showed the situation of Nohgye by comparing his mind with the mind of Yeon-Myung Do from the Confucian point of view, and a kind of behavioral mimesis based on his respect to Do and 'aesthetic representation of objective reality.' It is not coincidental that this mimesis was shown in the engraved words on Chwuiseok and the creation of ChwuiseokJeong that has the same name with Chwuiseok in Korea and China.