• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.16-21
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• 2017

Fire or electrical problem while DC electric traction vehicle operation caused by various reasons can lead to not only suspension of the operation, but also severe aftermath such as massive casualty. In this paper, fire analysis on DC electric traction vehicle caused by electrical breakdown on line breaker, which is in connection with the power supply, is presented. When the electric arc, the by-product of frequent line breaker operation, is not fully diminished, it leads to electrical breakdown and fire. Especially, electrical breakdown can be easily induced by the open-and-close operation of inner contractor inside line breaker, eventually followed by ground fault and generation of transient current. Electric arc is consequent on the ground fault and acts as possible ignition source, leading to fire. Also, during the repetitive operation of the line breaker, the contactor is separated each other and some copper powder is generated, and the copper powder provided breakdown path, resulting in fire.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.4 s.109
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• pp.420-427
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• 2006

In this study, wind loads transmitted to a transmission tower from transmission lines are mitigated using rotational viscoelastic dampers. First, the wind load characteristics in a transmission tower is investigated considering the effect of the transmission lines through stochastic analysis. The assemblage of the transmission line and insulator are modeled as a double pendulum system connected to the SDOF model of the tower. From the result of the stochastic analysis, the background component of the overturing moment caused by the wind loads acting on the transmission lines are found to have considerable portion in the total overturning moment. Based on this observation result, a strategy Installing rotational viscoelastic damper (VED) between tower arm and transmission line is proposed for the mitigation of the transmission line reactions, which play a role as dynamic loads on a transmission tower. For the purpose of verification, time history analysis is conducted for different wind velocities and VED parameters. The analysis result shows that the rotational VED is effective for the mitigation of the background component rather than the resonance component of the transmission line reactions and achieves the reduction ratio of 50% even for higher wind speed.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.59 no.2
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• pp.191-196
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• 2010

The electricity distribution system in Korea is adopting a multi-grounding system. Protection of this distribution system against lightning is performed by installing overhead ground wires over the high voltage wires, and connecting the overhead ground wires to the ground every 200 m. The ground resistance in this system is limited not to exceed $50\Omega$ and overhead ground wire and neutral wire are multiple parallel lines. Although overhead ground wire and neutral wire are installed in different locations on the same pole, this circuit configuration has duplicated functions of providing a return path for unbalanced currents and protecting the distribution system against induced lightning. Therefore, the purpose of this study is to analyze the induced lightning shielding effect according to the neutral wire installation structure of a 22.9kV distribution line in order to present a new 22.9kV distribution line structure model and characteristics. This study calculated induced lightning voltage by performing numerical analysis when an overhead ground wire is present in the multi-grounding type 22.9kV distribution line structure, and calculated the induced lightning shielding effect based on this calculated induced lightning voltage. In addition, this study proposed and analyzed an improved distribution line model allowing the use of both overhead wire and neutral wire to be installed in the current distribution lines. The result of MATLAB simulation using the conditions applied by Yokoyama showed almost no difference between the induced lightning voltage developed in the current line and that developed in the proposed line. This signifies that shielding the induced lightning voltage through overhead wire makes no difference between current and proposed distribution line structures. That is, this study found that the ground resistance of the overhead wire had an effect on the induced lightning voltage, and that the induced lightning shielding effect of overhead wire is small.

• International Journal of Costume and Fashion
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• v.8 no.2
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• pp.50-64
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• 2008

The purpose of this study is to classify Avatar fashion style through analysis of on-line Avatar Mall and to propose color pallette and fashion contents from fashion color analysis. The literature research focused on investigating the notion, characters and types of Avatar and relation of Avatar and self-image, clothing image and color image. In data research, 4 on-line portal sites Avatar Malls were analyzed and Avatar fashion style was classified. In addition, Avatar clothing color was analyzed. The research of this study are as follows: Firstly, Avatar in the cyber space represents 'me' of the real states. Avatar fashion helps to represent Avatar Image and clothing makes human image and identity as a social sign. Color helps to constitute clothing impression and human image, therefore clothing and color are the important elements to express self-image through Avatar in the cyber space. Secondly, Avatar Malls of 4 on-line portal sites are very similar and confuse Avatar users because of no standard of fashion style classification. Accordingly, the standard of fashion style classification should be made by a fashion expert, and the specific characters of every on-line portal site should be emphasized. Thirdly, as a result of the analysis of Avatar's clothing, the clothing is divided into a real world clothing and an imaginary world clothing. There are daily clothes, uniform, event clothes, story clothes and fantasy clothes. As a result of the color analysis of Avatar clothing, White, Red, Red Purple colors and bright and vivid tone are generally used for Avatar clothing. This study is significant to classify Avatar fashion style systematically, to notify sensitive and delicate users' sign and to make Avatar fashion image emotional and high-quality.

• 제어로봇시스템학회:학술대회논문집
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• 1996.10b
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• pp.273-276
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• 1996

We propose a new method to extract valid lines from a visual image. Unsupervised clustering method is used to assign each line to any of the line groups according to its orientation. During the low-level image processing we use an adaptive threshold method to reduce human supervision and to automate the processing sequence. To reduce the misclassification rate and to suppress the superiors line support regions at the clustering stage, the adaptive threshold method is consistently applied. Performing principal component analysis on each line support region provides an efficient method of obtaining line equation. Finally we adopt the theory of robust statistics to guarantee the quality of each extracted line and to eliminate the lines of poor quality. We present the experimental results to verify our method. With the proposed method, one can extract the lines according to the internal orientation similarities and integrate the whole process into one adaptive procedure.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.7
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• pp.11-17
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• 1982

In this paper, a reliable and convenient evaluation method for the adequacy of any radial distribution line's voltage drop is proposed for improvement of the voltage regulation of the distribution line under operation. Using the voltage measurement of the first load branch point and the last point on the given distribution line its average line voltage drop and the line voltage drop variance by pure load variation are computed. And by these values and allowable or required line drop from proper voltage regulation view point, present adequency index and operation improvement index of the line drop are newly introduced for the evaluation of the given distribution line's voltage regulation. As a result of application to the 4 cases of study, the proposed method is proved to be reliable and convenient.

• Journal of Ocean Engineering and Technology
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• v.27 no.6
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• pp.22-26
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• 2013

The purpose of this study was to improve the design of a mooring line by attaching a lumped mass to it on the seabed. A numerical analysis of the redesigned mooring system is performed to analyze the effect of the weight of the attached lumped mass using the commercial software Orcaflex. The ultimate tension of the mooring system with the lumped mass is compared with that of a bare mooring line in the original design. An appropriately designed weight for the lumped mass is found to induce a critical lifted point in the mooring line by floater motion in the ultimate condition to move toward the floater position from the anchor point, while maintaining a similar safety factor for the mooring line. On the other hand, it is shown that excess weight for the lumped mass induces snapping in a mooring line, resulting in low safety factor for the mooring system. The distance between lumped weights is shown to be a minor parameter affecting the safety of a mooring line, although a shorter line has an advantage from an economic point of view. Using the optimal weight for the lumped mass attached to the mooring line on a seabed reduces the mooring line length and installation area occupied by a mooring system under real sea conditions.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.325-339
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• 2007

This paper presents the analysis results to evaluate the application of separation sleeper boot of turnout in concrete track in subway. An analysis includes the dynamic load on turnout-bridge and the ballast improvement method of upbound and down line independent girder in servicing line. From the results, the aspect and the property of separation sleeper boot of turnout are evaluated. FE analysis explain the relationship between independent bridge and track behaviour of dynamic loads. The assessment of application based on FE analysis results in a good improvement method of servicing subway line is proposed.

• Proceedings of the KIEE Conference
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• 2004.07e
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• pp.27-29
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• 2004

This paper presents improved teaching and learning Gill for easily analysis tool of load flow of power system. This GUI includes not only contingency analysis function, but also calculating power loss from transmission line flow. The Gill is friendly for study for power system operation and control because picture provide a better visualizing of relationships between input parameters and effect than a tabula type result. This Gill enables topology and the output data of load flow for line outages to be shown on same picture page. Users can input the system data for power flow on the the picture and can easily see the the result diagram of bus voltage, bus power, line flow. It is also observe the effects of different types of variation of tap, shunt capacitor, loads level, line outages. Proposed Gill has been studied on the Ward-Hale 6-Bus system.

• Journal of Sensor Science and Technology
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• v.14 no.6
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• pp.438-443
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• 2005

In this paper, we introduce the on-line test of the current collection characteristics for HSR 350x(Korea High Speed Train project) that have been performed in the Kyoung-bu high-speed line since 2002. Through the analysis of measured data during on-line test, the variation trends of contact force between pantograph and catenary according to the track conditions and driving patterns are reviewed. This study shows that the track conditions do not affect on the dynamic performance between pantograph and the driving patterns are important factors in determining the good interaction of them.