• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1391-1393
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• 1999

This paper have analyzed sheath induced voltage in underground transmission cable system which will be operated with cable cover protection unit(CCPU). Simulation was carried out to analyze sheath induced voltage using on real cable system in the case with and without CCPU. Sheath induced voltage was also analyzed according to grounding method, fault resistance and fault angle. Simulation was performed using EMTP and ATP Draw, the simulation results represent whether the arrester is necessary or not in cable system.

• Proceedings of the KSR Conference
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• 2006.11b
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• pp.565-580
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• 2006

Set in constant increase and period current of lively technical development of railroad use and construction of cable stayed bridge railway bridge, one of bridge form of most suitable that think side police officer and the material enemy of bridge that use long rail, is increasing laying stress on the foreign countries. Main tower fixing department of this cable stayed bridge is consisted of main tower flange that support bearing plate, bay ring plate bearing plate, support end rib and diaphragm etc, as stress transmission mechanic that tensility of cable socket into normal force of main tower, and is used this time. These structural elements is very complex the structure and direction of load delivered from socket specially calbe particularly be different, and need FEM analysis that use Thick Shell element for suitable arrangement of mutual stress flowing grasping and absence that follow hereupon because all of the each support plate angle that suport this differ.

• Wind and Structures
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• v.28 no.4
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• pp.255-270
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• 2019

Aerodynamic configurations of bridge decks have significant effects on the aerostatic torsional divergence and flutter forsuper long-span bridges, which are onset for selection of suitable bridge decksfor those bridges. Based on a cable-stayed bridge with double main spans of 1500 m, considering typical twin-box, stiffening truss and closed-box section, which are the most commonly used form of bridge decks and assumed that the rigidity of those section is completely equivalent, are utilized to investigate the effects of aerodynamic configurations of bridge decks on aerodynamic instability performance comprised of the aerostatic torsional divergence and flutter, by means of wind tunnel tests and numerical calculations, including three-dimensional (3D) multimode flutter analysis and nonlinear aerostatic analysis. Regarding the aerostatic torsional divergence, the results obtained in this study show twin-box section is the best, closed-box section the second-best, and the stiffening truss section the worst. Regarding the flutter, the flutter stability of the twin-box section is far better than that of the stiffening truss and closed-box section. Furthermore, wind-resistance design depends on the torsional divergence for the twin-box and stiffening truss section. However, there are obvious competitive relationships between the aerostatic torsional divergence and flutter for the closed-box section. Flutter occur before aerostatic instability at initial attack angle of $+3^{\circ}$ and $0^{\circ}$, while the aerostatic torsional divergence occur before flutter at initial attack angle of $-3^{\circ}$. The twin-box section is the best in terms of both aerostatic and flutter stability among those bridge decks. Then mechanisms of aerostatic torsional divergence are revealed by tracking the cable forces synchronous with deformation of the bridge decksin the instability process. It was also found that the onset wind velocities of these bridge decks are very similar at attack angle of $-3^{\circ}$. This indicatesthat a stable triangular structure made up of the cable planes, the tower, and the bridge deck greatly improves the aerostatic stability of the structure, while the aerodynamic effects associated with the aerodynamic configurations of the bridge decks have little effects on the aerostatic stability at initial attack angle of $-3^{\circ}$. In addition, instability patterns of the bridge depend on both the initial attack angles and aerodynamic configurations of the bridge decks. This study is helpful in determining bridge decksfor super long-span bridges in future.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1499-1501
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• 1994

This paper studies on the outdoor field test facilities which are established for weather-resist and mechanical-resist property teat of composite insulator. We have established measuring and data acquisition system for various test conditions -leakage current, temperature, humidity, wind direction, wind velocity and rainfall. The merry-go-round test and salt fog test have been studied in order to evaluate non tracking property of rubber material. Especially we have checked the relationship between hydrophobicity and outdoor exposure degree by contact angle measurement.

• Proceedings of the KIEE Conference
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• 2004.11a
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• pp.248-250
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• 2004

We have investigated the surface state of 154kV polymeric insulators exposed to in-service conditions for about five years. In order to evaluate surface aging of silicone rubber exposed to real field environments, we used various analytic methods such as contact angle, ATR-FTIR, SEM-EDS. Although contaminants were accumulated on weathershed surface, polymeric insulator has retained its intrinsic surface hydrophocity. In addition, ATR-FTIR confirmed the diffusion layer of a low molecular weight silicone fluid on surface layer and no surface cracking and chalking were Indicated by SEM. Polymeric insulators have still retained their improved pollution performance over porcelain insulators. That will lead to very low frequency of flashovers throughout their useful life, often under contaminated conditions.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.21-30
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• 2008

In this study, to evaluate the aerodynamic stability of suspension bridge hanger ropes, the wind tunnel tests are carried out. It is found that the vortex induced vibration is detected only in single PE-coated PWS cable case. And the wake galloping is occurred in twin cables spaced $3\sim6$ cable diameters of cable center to center when the incidence angle of wind is only zero degree. In case of other incidence angles of wind except zero degree, the wake galloping or the wake flutter are showed in twin cables even outside range of the bounds of $3\sim6$ cable diameters. CFRC cable shows very stable for the twin cables regardless of the distance between two cables, and also for various incidence angles of wind. Thus the characteristic of CFRC rope overwhelms one of PWS cable in aerodynamic stability.

• Korean Journal of Materials Research
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• v.29 no.6
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• pp.378-384
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• 2019

Ice accumulation on Aluminum Conductor Steel Reinforced(ACSR) cable during winter is an important matter in terms of safety, economy, and efficient power supply. In this work, the ice adhesion strengths of ACSR cable oxidized during different periods(7 years oxidized and 15 years oxidized) are evaluated. At first, a plate type dry oxidation standard specimen, whose surface characteristics are similar to those of ACSR cable, is prepared. Dry oxidation standard specimens are heat-treated at $500^{\circ}C$ for 20, 60, and 120 minutes in order to obtain different degrees of oxidation. After the dry oxidation, surface properties are analyzed using contact angle analyzer, atomic force microscopy, spectrophotometer, and gloss meter. The ice adhesion strengths are measured using an ice pull-off tester. Correlations between the surface properties and the ice adhesion strength are obtained through a regression analysis indicating a Boltzmann equation. It is revealed that the ice adhesion strength of 15-year oxidized ACSR cable is approximately 8 times higher than that of ACSR-bare.

• Wind and Structures
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• v.22 no.2
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• pp.253-272
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• 2016

The paper concerns with the method and results of wind tunnel investigations of the Strouhal number (St) of a stationary iced cable model of cable-supported bridges with respect to different angles of wind attack. The investigations were conducted in the Climatic Wind Tunnel Laboratory of the Czech Academy of Sciences in $Tel{\check{c}}$. The methodology leading to the experimental icing of the inclined cable model was prepared in a climatic section of the laboratory. The shape of the ice on the cable was registered by a photogrammetry method. A section of an iced cable model with a smaller scale was reproduced with a 3D printing procedure for subsequent aerodynamic investigations. The St values were determined within the range of the Reynolds number (Re) between $2.4{\cdot}10^4$ and $16.5{\cdot}10^4$, based on the dominant vortex shedding frequencies measured in the wake of the model. The model was oriented at three principal angles of wind attack for each of selected Re values. The flow regimes were distinguished for each model configuration. In order to recognize the tunnel blockage effect the St of a circular smooth cylinder was also tested. Good agreement with the reported values in the subcritical Re range of a circular cylinder was obtained. The knowledge of the flow regimes of the airflow around an iced cable and the associated St values could constitute a basis to formulate a mathematical description of the vortex-induced force acting on the iced cable of a cable-supported bridge and could allow predicting the cable response due to the vortex excitation phenomenon.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.12
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• pp.940-949
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• 2013

In this paper, wrinkle reduction design was studied for triangular sail. Wrinkles in the solar sail membrane can change the load path and surface topology which may have an adverse effect on propulsion performance and controllability. In this study, wrinkle reduction strategies of adjusting cable angle, catenary and catenary-wire schemes were considered and the design parameters for wrinkle reduction were systematically investigated.

• Proceedings of the KIEE Conference
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• 2005.07a
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• pp.175-177
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• 2005

This paper analyzes transient behavior due to switching overvoltage in 22.9kV combined distribution systems. Computer models are consisted of distribution overhead line model, underground cable model and surge-arrester model in this paper. The computer models are made by EMTP/ATPDraw simulation and Line constants are calculated by ATP_LCC. This paper analyzes the various parameters affecting. These factors include closing angle and cable length.