• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.823-824
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• 2016

In general, distribution board, panel board and motor control center can be installed over a wide area such as residence of group, building, schools, factories, ports, airports, water service and sewerage, substation and heavy industries that are used to supply converts the voltages extra high voltage into optimal voltage. There are electrical accidents due to rise of contact temperature, loose contact of bus bar, deterioration of the contact resistance, overtemperatue of the bus bars. In this paper, we propose bus bar joints monitoring system with loose connection of bus bar, measuring the joint resistance of busbars and monitoring internal and external heat. The proposed system can be reduced the electrical accidents by maintenance of busbar joints and the temperature of the conductive contact surface of busbars.

• Tunnel and Underground Space
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• v.32 no.6
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• pp.478-490
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• 2022

TBM disc cutter, which is the main cutting tool of tunnel boring machine (TBM), is replaced when it is excessively worn during the boring process. Disc cutters are usually monitored by workers at cutterhead chamber, and they check the status and wear amount of cutters. Because cutterhead chamber is usually in dangerous circumstance due to high pressure and instability of excavation surface, the measurement by manpower occasionally results in inaccuracy of measurement result. In order to overcome the limitations, the real-time disc cutter monitoring techniques have been developed in some foreign countries. This paper collected the current status of disc cutter monitoring system from the literature. Several types of sensors are used to measure the cutter wear, and it is believed that the collected information can be useful reference when similar domestic technologies are developed in the future.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.441-448
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• 2022

In the distribution system, there are multiple power protection systems such as circuit breakers at substations, and reclosers, minimum circuit ampacities, fault interrupters on distribution lines. They are widely used to prevent partial outages, cascading power failure or blackout so that other healthy systems could maintain the integrity in case of the instant fault or permanent failure on the power lines. However, when a fault happens, it could cause a major black out due to the lack of the protection cooperation between the protection relay of the circuit breaker at a substation and a protection system on the distribution lines. To achieve the power system integrity better, it is required to develop the circuit breaker which can be operational within 1 cycle(16ms). In this study, the high speed circuit breaker which is filled up with eco-friendly gas is developed. This equipment achieved an excellent test results based on IEC 62271-111 standard. It is respected that this equipment would contribute to prevent the wide area blackout by isolating a fault area quicker and faster.

• Tribology and Lubricants
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• v.38 no.2
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• pp.41-52
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• 2022

Mineral electrical insulating oil, which is widely used in transformers, exhibits excellent cooling performance and transformer efficiency. However, given that it is composed of petroleum-based components, it is weak in terms of biodegradability. This causes environmental problems in case of leakage and a low flash point, which is a factor that would cause great damage in the event of a fire in a substation. In this context, the use of eco-friendly electric insulating oil composed of bio-based vegetable oil and synthetic ester, which has excellent biodegradability and flame retardancy performance, has recently been expanded to the field of electric power, and various research and development (R&D) studies are in progress. According to different research results, vegetable oil and synthetic ester manufacturing technology, thermal stability, oxidation stability, property change, and quality control, which are characteristics of eco-friendly electrical insulating oils, are major factors affecting the maintenance of insulating oil properties. In addition, power companies have established and operated quality control standards according to the use of eco-friendly electrical insulating oil as they expand the exploitatoin of renewable energy in electricity production. In particular, deterioration and oxidation characteristics were jointly identified in R&D as an important influencing factor according to the content of saturated and unsaturated fatty acids present in vegetable oils and synthetic esters in power transformer applications.

• KEPCO Journal on Electric Power and Energy
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• v.8 no.1
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• pp.5-7
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• 2022

KEPCO's plan is undergoing a trial operation to replace the open-loop section with ring main units configuration where underground distribution lines are installed, by linking the multi-way circuit breakers auto (MCA) on the power side of each pad-mounted transformer. However, ring main units application mentioned above may cause the ripple effects, when implementing the configuration without a study of protection coordination. Because ring main units with classical pre-set protection devices contribution in fault condition didn't consider yet. For the reliable ring main units operation, it is necessary to resolve several protection issues such as the protection coordination with substation side, prevention of the transformer inrush current. These issues can radically deteriorate the distribution system reliability Hence, it is essential to design proper protection coordination to reduce these types of problems. This paper presents a scheme of ring main units' configuration and MCA's settings of time-current curves to preserve the performance of protection coordination among the switchgears considering constraints, e.g. prevention of the ripple effects (on the branch section when a transformer failure occurs and the mainline when a branch line failure occurs). It was confirmed that the propagation of the failure for each interrupter segment could be minimized by applying the proposed TCC and the interrupter settings for the MCAs (branch, transformer). Further, it was verified that the undetected area of the distribution automation system (DAS) could be supplemented by having the MCA configurated ring main units operate first, instead of the internal protection equipment in the transformer such as the fuse, STP when a transformer failure occurs.

• Tunnel and Underground Space
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• v.33 no.4
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• pp.244-254
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• 2023

The disc cutter mounted on the Tunnel Boring Machine (TBM) is subjected to cutting forces in three dimensions during rock excavation process. It is widely known that the cutting forces increased with the strength of the rock mass, while the rolling force can be significantly increased when the disc cutter encounters abnormal rotation. Therefore, the cutting force acts on the disc cutter provides important information because it represents the conditions of the rock mass and the disc cutter. For these reasons, several studies have been conducted to measure the cutter forces in real-time. This paper introduces the current status of research on the cutter force measurement of TBM disc cutters, which has been reported in the literature. It is judged that this paper can be a useful reference material when similar technologies are developed in Korea in the future.

• Smart Media Journal
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• v.12 no.2
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• pp.91-102
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• 2023

The Energy Management System (EMS) communicates with power plants and substations, monitors the substations and plant operational status of the transmission and substation system for stability, continuity, real-time, and economy of power supply, and controls power plants and substations. Currently, the power exchange EMS communicates with power plants and substations based on the serial communication-based Distributed Network Protocol (DNP) 3.0 protocol. However, problems such as the difficulty of supply and demand of serial communication equipment and the lack of installation space for serial ports and modems are raised due to the continuous increase in new facilities to perform communication, including renewable power generation facilities. Therefore, this paper presents a TCP/IP-based communication method instead of the existing serial communication method of the power exchange EMS, and presents a security risk analysis that may occur due to changes in the communication method and a countermeasure to the security risk.

• Proceedings of the Korean Society of Crop Science Conference
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• 2022.10a
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• pp.268-268
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• 2022

Protein is a major nutrient of food and has long been studied for nutritional and utility value. Among them, rice protein is attracting attention because of its hypoallergenic characteristics and nutritional value. Mutant DM225 with increased protein content was selected by EMS treatment on the weed rice Dharial. QTL analysis of Protein content was carried out using BC₂F₂ populations derived from a cross between "Hanareum2" as a recurrent parent and "DM225" as a donor parent. The protein content of populations was between 5~11%, with an average of 7.7%. To identify QTLs related to Protein content, 117 KASP markers(polymorphic ratio: 15%) showing polymorphisms between the parents were genotyped for the BC₂F₂ population. One QTL was detected between markers SK07 06 and SK07_10 on chromosome 7(LOD: 28.1). This QTL explained 71.4% of the phenotypic variance for Protein content. This QTL will be useful for protein-related rice breeding program.

• Tunnel and Underground Space
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• v.33 no.5
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• pp.425-434
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• 2023

To measure the wear amount of the TBM disk cutter in real time, it is important not only to automate the measurement using sensors, but also to stably transmit the measured data to the information processing system. In this study, we investigated the viability of utilizing Bluetooth Low Energy (BLE) technology to wirelessly transmit sensor data from the TBM cutter head to a receiver located at the chamber's rear. Through laboratory experiments, we analyzed the Received Signal Strength Index (RSSI) of the receiver considering various signal strength of the transmitter, separation distances between the transmitter and receiver and chamber fill materials. Our results demonstrate that wireless data transmission is feasible across all tested conditions when the transmitter signal strength is 0 dBm or higher.

• The Journal of the Korea institute of electronic communication sciences
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• v.19 no.1
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• pp.53-64
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• 2024

The Yeongnam southeastern region, with Ulsan as its focal point, is planning large-scale floating offshore wind power projects. Additionally, due to the establishment of new nuclear power plants and the extension of existing ones, there is a demand for the expansion of the power grid. The government has announced plans to establish a new power grid for this region as part of the 10th power supply plan. However, there are anticipated challenges in the actual construction phase, primarily because of the presence of national parks and cultural heritage protection zones near Gyeongju. As a result, this study presents an alternative approach that minimizes the creation of new power lines by utilizing existing ones. Using the Power System Simulator for Engineers (PSS/E), an analysis of transient stability was conducted and demonstrated its feasibility.