• Proceedings of the KSR Conference
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• 2002.10a
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• pp.408-413
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• 2002

From the moment that electricity is applied to a relay, a wheel turned, or a valve opened, the process leading to the need for maintenance begins, The uninitiated will tell you that the Maintenance man is someone who repairs something when it has gone wrong. Unfortunately, in any large engineering concern, such as a railway, it is not possible to work on the principle that only when something breaks down should it get any attention. The failure of one contact, diode or bearing could well stop not only the assembly of which it is a part, but the flow line or process, with loss of revenue, and clientele, and often with effects on the safety of both staff and the traveling public. So, we have to establish the reliable and cost-effective maintenance system to resolve these problems.

• Journal of Electrical Engineering and Technology
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• v.4 no.1
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• pp.13-18
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• 2009

Because the existing Human-Machine Interface (HMI) for the conventional substation cannot dynamically indicate the configuration information of the Substation Automation System (SAS). In this paper, an intelligent station HMI is proposed for IEC 61850 based substation. The program of the proposed HMI not only can automatically generate the layout of single line diagram, but can also indicate the communication network and functions of IEDs by reading SCL files. It greatly helps monitor the operation status, communication network and each IED dynamically, such as failure detection in SAS. Furthermore, this paper presents the possibility of developing new software for SAS with the full use of IEC 61850-6. Once the software is complete, there is no need to change it when the substation is upgraded or when it is migrated to other IEC 61850 based substations, which is a cost-effective solution.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.511-512
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• 2006

The salt contamination on the distribution facilities is one of the major concern areas because more than 90% of salt contaminated failure occurs in distribution facilities. The periodic measurement of the Equivalent Salt Deposit Density(ESDD) is essential to manage and operate the power line. The ESDD has taken from the 112 position which is located on the coastline of the Korean Peninsula. The ESDD will be presented with the location and the distance from the coastline.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2013.10a
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• pp.699-705
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• 2013

This paper presents vibration testing, control, and finite element analysis of a piping system, which is subjected to the changes in fluid levels. Nuclear power plants typically employ a cooling system that uses sea water. These systems are subjected to dynamic characteristic changes caused by sea-level variations, which introduces failures of cooling system components. Therefore in this study, analytical and experimental studies were performed to understand the effect of sea-level changes on the dynamic characteristics of piping systems. It was shown that, as the sea-level increases, pipe's natural frequencies decreases in relation to its mode shape. A 1/14 scale model was also built to compare the results obtained by the analytical study. A good agreement between experiment and analytical studies were observed. Finally, an on-line resonant frequency identification system was proposed and developed, which utilizes piezoelectric transducers as sensors and actuators, in order to avoid catastrophic failure of piping systems.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1821-1832
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• 2008

Presently, the policy base of our government focusing on the privatization of public corporation with the transfer of political power, KORAIL, one of public corporation, also can not be free from there. the policy line of our government to privatize KORAIL following the developed countries' precedent has been advocated repeatedly already since the 1990's. whenever it happened, it was true that government as well as KORAIL researched on the success or failure case of privatization in developed countries, but considering lessened pressure to the public corporation during Nor's administration, I researched on the privatization of overseas' railways to remind you of what is advantage or disadvantage. In this research, treated Japan's case which is considered one of most successful privatization story in several cases. with the result of this research, which is expected to be utilized setting the policy of privatization direction, if KORAIL tried to be privatized once again.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.248-254
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• 2008

Electric railway system consists of traction power system, rolling stock, track, and overhead line system. A railway substation transforms the electric power transmitted from a electric power company and supply it to the railway power system for the operation of traction system.. It is very important to prevent a possible accident and keep the security of electric power system. This paper proposes a reliability analysis of AC railway substation by using Fault Tree Analysis(FTA). Failure rates of each equipment of railway substation are used to evaluate the reliability of railway substation. The analyzed results can be used to improve the system reliability. FTA is performed by the commercialized program of Relex(Ver. 7.7).

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.540-542
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• 2019

This paper proposes an open-phase fault control system using 3-phase neutral voltage. The proposed control system is designed as a new topology which uses the potential difference between neutral point and ground of three phase. The open-phase detection system is also configured to Y-wiring of three capacitance devices of the same capacity to each line of three phase power source R-S-T. This paper also designs a mobile phone application for remote alarm of open-phase fault.

• Korean Journal of Construction Engineering and Management
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• v.5 no.6 s.22
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• pp.212-217
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• 2004

Carbon fiber reinforced plastic(CFRP) plate Is one of the alterative materials for soengthening of reinforced and prestressed connote members due to excellent strength and light weight In this paper, the behavior of beams strengthened with CFRP plate and CFS(Carbon fiber sheet) is observed and analyzed from the test results. Especially specimens with thick plate is tested when large moment and large shear lone appear in same position. The main failure mode is a peeling-off of the CFRP plate near the loading points due to flexural-shear crack, Because of this failure mode, failure load is not linearly proportional to the thickness of CFRP plates. When beam is wrapped with CFS around oかy loading point it does not influence on the failure loads. Depending on the loading pattern, it is necessary to consider different design criteria for reinforced concrete members with external reinforcement. When line moment and large shear force appear in same location, maximum thickness may limit to 0.6mm and ratio between moment of strengthened beam and moment of unstrengthened beam is proposed 1.5-2.0. In order to use the plate of thicker than 6mm, CFS may be extended to the location which moment of strengthened beam is 1.5 times than moment of unstrengthened beam.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.89-96
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• 2006

Recent ULSI and multilevel structure trends in microelectronic devices minimize the line width down to less than $0.25{\mu}m$, which results in high current densities in thin film interconnections. Under high current densities, an EM(electromigration) induced failure becomes one of the critical problems in a microelectronic device. This study is to improve thin film interconnection materials by investigating the EM characteristics in Ag, Cu, Au, and Al thin films, etc. EM resistance characteristics of Ag, Cu, Au, and Al thin films with high electrical conductivities were investigated by measuring the activation energies from the TTF (Time-to-Failure) analysis. Optical microscope and XPS (X-ray photoelectron spectroscopy) analysis were used for the failure analysis in thin films. Cu thin films showed relatively high activation energy for the electromigration. Thus Cu thin films may be potentially good candidate for the next choice of advanced thin film interconnection materials where high current density and good EM resitance are required. Passivated Al thin films showed the increased MTF(Mean-time-to-Failure) values, that is, the increased EM resistance characteristics due to the dielectric passivation effects at the interface between the dielectric overlayer and the thin film interconnection materials.

• Composites Research
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• v.18 no.2
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• pp.20-29
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• 2005

To evaluate the flexural deformation and strength of composite motor case above the glass transition temperature$(T_g),\;170^{\circ}C$, of resin material, a finite element analysis(FEA) model in which material non-linearity and progressive failure mode were considered was proposed. The laminated flexural specimens which have the same lay-up and thickness as the composite motor case were tested by 4-point bending test to verify the validity of FEA model. Also. mechanical properties in high temperature were evaluated to obtain the input values for FEA. Because the material properties related to resin material were highly deteriorated in the temperature range beyond $T_g$, the flexural stiffness and strength of laminated flexural specimen in $200^{\circ}C$ were degraded by also $70\%\;and\;80\%$ in comparison with normal temperature results. Above $T_g$, the failure mode was changed from progressive failure mode initiated by matrix cracking at $90^{\circ}$ ply in bottom side and terminated by delamination at the center line of specimen to fiber compressive breakage mode at top side. From stress analysis, the progressive failure mechanism was well verified and the predicted bending stiffness and strength showed a good agreement with the test results.