• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.239-245
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• 2005

Through the fatigue test of plastic gears using polyacetal polymer, this research aims at providing basic data for not only specifying operation conditions of plastic gears, but also designing dimensions of plastic gears with giving fatigue life and the estimated equation of fatigue life of plastic gears. That is, from the fatigue life curves, the estimated equation of fatigue life of plastic gears is taken out. For the estimated equation of fatigue life of plastic gears, this research provides two test methods; one is preserving non-limited temperature of tooth flank, the other is preserving limited temperature of tooth flank. As results, how the temperature of tooth flank affects the fatigue life is shown. In addition, based on the endurance limit, the essential factors of the unit load and K-factor are determined, which are needed in the design of gear by bending strength and surface durability.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.21-28
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• 2001

Analysis of squeal noise generated during brake operation is an important task for the improvement of brake noise prob-lem. By the use of measuring instrument and techniques, test and evaluation process are to be developed systematically in quantitative analysis. The cost far test and evaluation 7an be reduced, and the technical power can be raised by the devel- oped system.

• Journal of the Korean Society for Railway
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• v.8 no.6 s.31
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• pp.525-532
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• 2005

Fatigue life of catenary wires in various environments is reduced when stress is concentrated on some points, which are often found in corroded areas by surrounding pollutants. Therefore, the fatigue test were performed in order to investigate the effect of the surface corrosion on the destructive behavior in service environment and accelerated corrosion environment as well as th examine the corrosive property and mechanism of the catenary wires. In the fatigue test of the messenger stranded wire, the corrosion degraded materials showed 35~50% of fatigue life at a same stress amplitude compared to original material. Because the catenary wires have variable load by the interaction of periodic contacts with pantographs the maximum stresses of trolley wire and messenger wire calculated by simulation at the messenger wire during operation was estimated thought the corrosion behavior interpretation of variable stress and fatigue test.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.124-130
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• 2014

In highly reliable and durable systems, failures due to aging might result in catastrophes. Aging monitoring techniques to prevent catastrophes by predicting such a failure are required. This paper presents a scan-based on-line aging monitoring scheme which monitors aging during normal operation and gives an alarm if aging is detected so that the system users take action before a failure occurs. We illustrate our modified scan chain architecture and aging monitoring control method. Experimental results show our simulation results to verify the functions of the proposed scheme.

• Journal of the Korean Society for Railway
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• v.10 no.1 s.38
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• pp.84-87
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• 2007

Auxiliary power supply developed by domestic technology has very important function that not only effect on main power converter & inverter system, traction motor and train control system which are related to performance of train, but also influence on power supply for HVAC(Heat, Ventilation, Air-conditioning) and lighting device which are related to comfort of passengers. This paper shows characteristic test results of auxiliary power supply such as working condition and performance, which is associated with velocity of train, operating mode and surrounding equipment, through test running. And, it propose a modification of design parameter for stabilizing operation and improving reliability.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.1
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• pp.55-59
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• 2016

In Europe, polypropylene-insulated HV class cable with high temperature and no cross-linking was commercialized following the MV class. Our company also started a study of the polypropylene-insulated cable in 2013 and was carried out thermal, physical and electrical test. In addition, polypropylene-insulated cable was tested for compatibility with conventional joints and terminations in emergency condition and the accelerated life test for verifying their design life is in progress. The results of this study will be used to establish a standard specification and operation conditions of the polypropylene-insulated cable.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1186-1192
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• 2012

In Jeju Smart Grid field test, Zigbee technology is being used as one of customer side solutions for AMI. Although Zigbee networks that provides effective connectivity and control among devices are advantages in ease of implementation and use, the data can be exposed to cyber attacks such as eavesdrop, unauthorized data dissemination and forgery. Currently authentication and confidentiality services are provided with the network and link keys generated based on public key pairs that are pre-installed in offline. However, the network is vulnerable once a hacker intrudes into a local network because operation and management policies for the generated keys are not well-established yet. In this paper, the vulnerability of the Zigbee security system in the customer side environment of Jeju Smart Grid field test is analyzed. Then, two-way authentication with the unique identifiers of devices and user-specific group management policies are proposed to resolve the vulnerability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.10
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• pp.102-110
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• 2012

This paper propose the advanced topology of UPQC, its DC link is connected with Lithium battery, to compensate the momentary interruptions. The proposed system can be operated as UPS mode using the parallel inverter, which control the charge or discharge of battery, in case of the interruption. We dvelop 100kVA UPQC using the proposed topology to rise the power quality and the reliability of Microgrid. We verify its usefulness through voltage compensation test, UPS operation test and etc. using Microgrid test facility.

• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1353-1355
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• 2003

Total six units of 3kW photovoltaic (PV) system and data acquisition system (DAS) are constructed for analyzing performance of PV system at field demonstration test center of Gwang-Ju in Korea. As climatic and irradiation conditions are varied, operation characteristics of the PV system are collected and analyzed in data-acquisition system. Furthermore, not only performance test of each PV system component such as PV module and power conditioning system, but also performance of total PV system e.g. system efficiency, electric power and loss factor at the site are reviewed.

• Journal of the Society of Disaster Information
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• v.6 no.1
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• pp.140-152
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• 2010

In designing a railroad bridge, the fatigue is one of the main factors to be considered for ensuring safe operation. Especially, for a new type of a structural member, which has not been adopted to railroad bridges, the fatigue performance should be checked. In this paper, the fatigue characteristics of an IT girder are examined. The IT girder is a new type of a prestressed concrete girder which has two prestressed H-beams in the top of the girder to give the girder additional sectional capacity. To obtain the fatigue performance, a 10m IT girder specimen is designed, and a repeated load test is performed by applying the load cyclically two million times. The magnitude of the repeated load is determined considering the stress level under the service condition. During the test, static load tests are performed to identify the stiffness degradation. The fatigue performance of the girder is checked according to the Japanese and the CEB-FIB design codes. The fatigue test result shows that the IT girder satisfies both design codes.