• Proceedings of the KWS Conference
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• 1997.05a
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• pp.65-68
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• 1997

Fracture behavior of ex-serviced 1Cr-0.5Mo steel was measured at room(24$^{\circ}C$) and elevated(538$^{\circ}C$) temperature and compared with that measured with virgin 1Cr-0.5Mo steel. Compact C(T) specimens were machined from the base and welded test materials. In case of the C(T) specimens of the weld, fatigue precrack was introduced along the fusion line so that a crack growth should occur along the region of heat affected zone. It was observed that the J-R curve of the serviced material was significantly lower than that of the virgin material at room temperature. Brittle fracture was observed in the serviced material. On the other hand at elevated temperature no noticeable difference was found between the J-R curves of the virgin and the serviced material. The measured J-R curves were also compared with those of the 1.25Cr-0.5Mo steel from other literatures. Optical microscopy and SEM examination of the serviced material reveal the carbide in/along the grain boundary which shows material degradation due to long-term usage.

• Journal of the Korean Society of Safety
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• v.12 no.2
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• pp.45-56
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• 1997

Fracture behavior of ex-serviced 1Cr-0.5Mo steel was measured at room($24^{\circ}C$) and elevated($538^{\circ}C$) temperature and compared with that measured with virgin 1Cr-0.5Mo steel. Compact C(T) specimens were machined from the base and welded test materials. In case of the C(T) specimens of the weld, fatigue precrack was introduced along the fusion line so that following crack growth should occurs along the region of heat affected zone. It was observed that the J-R curve of the serviced material was significantly lower than that of the virgin material at room temperature. Brittle fracture was observed in the serviced material. On the other hand, at elevated temperature no noticeable difference was found between the J-R curves of the virgin and the serviced material. The measured J-R curves were also compared with those of the 1.25Cr-0.5Mo steel obtained from the other literatures. Optical microscopy and SEM examination of the serviced material reveal the carbide in/along the grain boundary which shows material degradation due to long-term usage. An example of application of the measured J-R curves is shown.

• The Journal of the Convergence on Culture Technology
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• v.6 no.2
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• pp.481-487
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• 2020

In this study, finite element analysis was performed to evaluate the track irregularity of the existing track system on urban transit according to the large-scale excavation work that is constructed adjacent to the serviced line. Based on the numerical analysis, the effect of track irregularity generated during the step-by-step construction process was analytically derived, and the stability in terms of track deformation was evaluated through comparison with related standards. As the results, in the case of track irregularity items evaluated based on the relative displacement difference at a certain distance, such as alignment and vertical irregularity, it occurred most clearly at the location where deformation of the existing structure begins, such as the end point of adjacent excavation work. On the other hand, the overall vertical and horizontal displacement of the track was the largest deformation at the center of the construction section. The vulnerable position of the deformed side of the existing structure due to adjacent excavation is analytically proven that the both of the end point section and the center of the construction can be a vulnerable position in terms of track irregularity.

• East Asian mathematical journal
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• v.31 no.5
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• pp.707-716
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• 2015

We consider a queueing system with N-limited nonstop forwarding. In this queueing system, when the server breaks down, up to N customers can be serviced during the repair time. It can be used to model an assembly line consisting of several automatic stations and a manual backup station. Within the framework of $Geo^X/D/1$ queue, the matrix analytic approach is used to obtain the performance of the system. Some numerical examples are provided.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.206-210
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• 2005

The Maglev system is environmentally friendless system, has excellent running capabilities and lower life cycle cost. The Maglev has been developed by Germany and Japan since 1970's. Then, Transrapid of Germany, super high speed type, had started for commercial operating at Sanghai of China in the early of 2004. In March of this year, HSST of Japan, urban type, had been serviced at Tobukyuro Line which links between Nagoya and Aichi. Recently, in Korea, Maglev system has been reviewed for commercial application.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1595-1596
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• 2015

This study presents the review of technical requirements of safety and security for the developed high-speed freight train which will be serviced on the existing route of the high-speed line. There is no any experience to make a system design of high-speed freight train in Korea until now. We need to make a new regulations of commercial service.

• The Journal of the Convergence on Culture Technology
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• v.5 no.4
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• pp.401-406
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• 2019

The three-dimensional precision numerical analysis was performed using the finite element model applied with the railway track model consisting of rails, sleepers, and track elastic springs(ballast, rail pad). As a result of analyzing the track deformation level of the existing tracks due to the excavation work adjacent to the railway facilities, it was found that the track irregularity evaluation criteria (allowed values) of both conventional and high-speed railways lines were satisfied. Based on the numerical analysis using the track model, it was analyzed that the results of the prediction of the track irregularity due to the excavation work and the level of the track deformation occurring at the actual site could be approximated as closely as possible.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.1
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• pp.115-129
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• 2010

As the fixed mobile communication tools using the internet are developed, the off-line services are serviced through on-line on the internet. our society is divided into the real world and the cyber world. In the cyber world, the authentication to the user is absolutely required. The authentication is divided into the real-name authentication and the anonymous authentication by the kind of the internet service provider. There are some ISPs needed the real-name authentication and there are others ISPs needed the anonymity authentication. The research about the anonymity authentication is steadily established to these days. In this paper, we analyze the problem about blind signature, group signature, ring signature, and traceable signature. And we propose a method of anonymity authentication using the public certificate. In the proposal, the anonymity certificate have the new structure and management. Certificate Authority issues several anonymity certificates to a user through the real-name authentication. Several anonymity certificates give non-linked and non-traceability to the attacker.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.273-281
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• 2010

To install turnout on the main line of high speed railway running 300km/h, measures of rail destressing of existing line, speed-up plan, shortening the installation time and other important technical measures should be considered to reduce the inconvenience of passenger. In particular, for the newly constructing Ohsong and Kimcheon-Gumi station in KyongBu high speed line, it must be difficult to install divided turnout part because it should be done within short night block out hours (6 hours per day) and KTX trains are safely serviced just in time, which is not only the first time in the domestic and but also very rare practical experience in the world. This thesis is covered with experienced work conditions, required equipments and various safety measures, etc.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.1
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• pp.79-86
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• 2008

Domestic and foreign follows the trend which is that safety checkup of electrical facilities is serviced by on-line system with joining information technology. This paper research improvement of what kind of system and law for market environment of electric power value added service. For improvement of market environment of electric power value added service, this paper researches improvement of on-line monitoring system and necessity of arc interruption and revision of arc related law.