• Journal of Electrical Engineering and Technology
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• v.12 no.6
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• pp.2419-2425
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• 2017

In this paper, a system for the precise detection of arcs is proposed for a rigid catenary using a spectrometer. For this purpose, a miniature rigid catenary contact-loss simulator was used. Experiments were performed by varying the amplitude of the excitation frequency with which a real arc can occur using a simulator in the range of 5 to 15 mm. The range of the radiated wavelength of the copper, which is a material in the rigid catenary, and the irradiance were measured using a spectrometer according to the generated contact loss. In addition, the amount was monitored over time and its characteristics were analyzed. The voltage and current of the load were analyzed when the arc occurred due to contact loss. The analytical results will be applied to detect rigid catenary arcs and used as a monitoring system for real vehicles developed in the future. This will prevent abrasion and disconnection in rigid catenary systems.

• Journal of Korea Multimedia Society
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• v.22 no.12
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• pp.1438-1446
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• 2019

Recently, the number of mobile users as well as high-speed Internet user has been increasing rapidly. Moreover, traffic is growing fast as services that provide real-time content such as Youtube and Netflix become popular. The problem of traffic control in real-time content services is important because many people use cell phones to receive real-time content. In this regard, the field of CCN is currently being studied. We studied the mobility of nodes among CCN research fields. Node mobility can be divided into three categories : consumer mobility, intermediate node, and provide mobility. In this paper, we propose Mobility Node Support(MD-INS) to support the intermediate-node mobility in CCN real-time services. Experimental results show that the proposed scheme shows better performance than CCN in terms of service disconnection time and packet loss.

• Proceedings of the KIEE Conference
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• 2006.07a
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• pp.525-526
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• 2006

Recently, much research has been done and many improvements have been developed for islanding protection of distributed generation(DG). Anti-islanding protection for DG must be act very quickly to prevent equipment damage at the time of disconnection and for the safety of maintenance and repair personnel. DG-based detection methods have included both passive and active types, and now research has shifted towards new anti-islanding detection methods that make up for the defects of the previous types. Because differences occur between the utility grid and the DG when connecting and disconnecting depending on the phase difference, voltage, current, relative capacity of electric power, and system operation characteristics, voltage phase angle is an important consideration. In this paper, we simulated islanded operation characteristics comparing phase difference of DG and the connected utility grid, and analyzed various parameters (real power, reactive power, RMS voltage, RMS current, power factor angle, and frequency) by varying the DG's voltage phase angle. Using this information, we propose a suitable DG voltage phase angle for enhanced passive islanding detection techniques.

• Journal of Power Electronics
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• v.16 no.3
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• pp.1012-1024
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• 2016

This study deals with an on-line software fault detection, localization, and system reconfiguration method for electrical system drives composed of three-phase AC/DC/AC converters and three-phase permanent magnet synchronous machine (PMSM) drives. Current sensor failure (outage), speed/position sensor loss (disconnection), and damaged DC-link voltage sensor are considered faults. The occurrence of these faults in PMSM drive systems degrades system performance and affects the safety, maintenance, and service continuity of the electrical system drives. The proposed method is based on the monitoring signals of "abc" currents, DC-link voltage, and rotor speed/position using a measurement chain. The listed signals are analyzed and evaluated with the generated residuals and threshold values obtained from a Sliding Mode Current-Speed-DC-link Voltage Observer (SMCSVO) to acquire an on-line fault decision. The novelty of the method is the faults diagnosis algorithm that combines the use of SMCSVO and adaptive thresholds; thus, the number of false alarms is reduced, and the reliability and robustness of the fault detection system are guaranteed. Furthermore, the proposed algorithm's performance is experimentally analyzed and tested in real time using a dSPACE DS 1104 digital signal processor board.

• Korean Journal of Remote Sensing
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• v.39 no.1
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• pp.77-86
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• 2023

Ship detection is widely used in areas such as maritime security, maritime traffic, fisheries management, illegal fishing, and border control, and ship detection is important for rapid response and damage minimization as ship accident rates increase due to recent increases in international maritime traffic. Currently, according to a number of global and national regulations, ships must be equipped with automatic identification system (AIS), which provide information such as the location and speed of the ship periodically at regular intervals. However, most small vessels (less than 300 tons) are not obligated to install the transponder and may not be transmitted intentionally or accidentally. There is even a case of misuse of the ship'slocation information. Therefore, in this study, ship detection was performed using high-resolution optical satellite images that can periodically remotely detect a wide range and detectsmallships. However, optical images can cause false-alarm due to noise on the surface of the sea, such as waves, or factors indicating ship-like brightness, such as clouds and wakes. So, it is important to remove these factors to improve the accuracy of ship detection. In this study, false alarm wasreduced, and the accuracy ofship detection wasimproved by removing wake.As a ship detection method, ship detection was performed using machine learning-based random forest (RF), and convolutional neural network (CNN) techniquesthat have been widely used in object detection fieldsrecently, and ship detection results by the model were compared and analyzed. In addition, in this study, the results of RF and CNN were combined to improve the phenomenon of ship disconnection and the phenomenon of small detection. The ship detection results of thisstudy are significant in that they improved the limitations of each model while maintaining accuracy. In addition, if satellite images with improved spatial resolution are utilized in the future, it is expected that ship and wake simultaneous detection with higher accuracy will be performed.

• Proceedings of the KIPE Conference
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• 2013.11a
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• pp.258-259
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• 2013

Load connection or disconnection makes instantaneous sag & swell in 3-phase grid. When unbalance state occurs, between sensed phase voltage and actual phase voltage may have discrepancy. It makes difficult to detect accurate sag & swell, so it is hard to satisfy the standard for switching ESS system to UPS mode. In this paper, we analyzed unbalanced 3-phase voltage, and compensated the actual sag & swell magnitude.

• Journal of Aerospace System Engineering
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• v.17 no.6
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• pp.100-107
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• 2023

Open-phase fault in a Permanent Magnet Synchronous Motor (PMSM) occurs due to disconnection of phases of motor windings or inverter switch failures. When an open-phase occurs, it leads to the generation of torque ripples and vibrations in the motor, which can have a critical impact on the safety of the vehicle (including aircraft) using a PMSM as an actuator. Therefore, rapid fault detection and classification are essential. This paper proposes a classification method for detecting open-phase faults and locating fault positions in a PMSM used in aircraft applications. The proposed approach uses an Extended Kalman Filter for fault diagnosis, and it subsequently classifies faults using a Multiple Model filter.

• Journal of the Korea Institute of Military Science and Technology
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• v.10 no.1
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• pp.44-54
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• 2007

In the military field, according to the MIL-STD-188-220, which is an Ad-Hoc communication protocol used for sending out or receiving data and voice smoothly among nodes in the situation that wireless communication nodes move arbitrarily, data communication is cut off because nodes can not know topology changes perpetually in the link disconnection state due to node movement in the case that transmitters do not confirm whether data is delivered to receivers or not, and transmit only the data having routine precedence continuously. In order to solve this problem, we have proposed the technique that makes efficient data communication possible by achieving a rapid topology change detection and link information update using TEST frame. We have analyzed TEST frame application effects in the two aspects of the topology update delay time and the data transmission success ratio.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.4
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• pp.239-243
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• 2011

In wireless ad-hoc network, the detection of link breakage and re-establishing the route path causes lots of network overhead and results in communication delay. In the LBN method, the node causing a link breakage actively sends a message to neighbors so that they can instantly start re-establishing process of new path. In this paper we describe the result of network simulation we performed using NS2 to show the effectiveness of LBN method.

• Journal of Cerebrovascular and Endovascular Neurosurgery
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• v.26 no.1
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• pp.30-36
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• 2024

Objective: This study aims to investigate the efficacy of microsurgery with intraoperative indocyanine green (ICG) angiography as a treatment approach for ethmoidal dural arteriovenous fistula (DAVF). Methods: Between January 2010 and July 2021, our institution encountered a total of eight cases of ethmoidal DAVF. In each of these cases, microsurgical treatment was undertaken utilizing a bilateral sub-frontal interhemispheric approach, with the aid of intraoperative ICG angiography. Results: ICG angiography identified bilateral venous drainage with single dominance in four cases (50%) of ethmoidal DAVF, a finding that eluded detection during preoperative transfemoral cerebral angiography (TFCA). The application of microsurgical treatment, in conjunction with intraoperative ICG angiography, resulted in consistently positive clinical outcomes for all patients, as evaluated using the Glasgow Outcome Scale (GOS) at the 6-month postoperative follow-up assessment; six patients showed GOS score of 5, while the remaining two patients attained a GOS score of 4. Conclusions: The use of intraoperative ICG angiography enabled accurate identification of both dominant and non-dominant venous drainage patterns, ensuring complete disconnection of the fistula and reducing the risk of recurrence.