• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.3
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• pp.208-214
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• 2011

In this thesis, the partial discharge according to applied voltage and variations of cross-sectional area and length of the conductor related to general condition for using cable was measured in order to study degradation diagnosis for 2-Core cable of the PVC insulator used in industrial fields for other safety installations. Also the thermal degradation conditions under various installation circumstances of cables were studied by assuming degradation conditions with each different degradation rate (50%, 67%, 100%) such as variation in degradated temperature, thermal exposure time, normal state, partially degradated state and overall degradated state for thermal degradation diagnosis. The quantity of electric discharge (V-Q) according to applied voltage was measured for measurement of inception voltage and extinction voltage. The quantity of electric discharge and the number of electric discharge (Q-N) were measured with applied voltage kept constantly. In addition, pictures were taken using SEM (scanning electron microscope) to compare the surface of external insulator to degradated state of internal insulator according to thermal degradation temperature and also compare the surface of external insulator to degradated surface state of internal insulator according exposure time of cables to thermal stress.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1761-1766
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• 2016

In this paper, we investigated the fusing current of carbon fiber and thermal properties of carbon fiber and metal shielded cable due to over-current. The fusing current value for the metal-coated carbon fiber was 5.3A in 3K, 7.4K and 13.05A in 12K. And if it exceeds 50% of the fusing current was broken with a rapid voltage rise. In the case of carbon fiber shielded cable, the temperature of the PVC sheath increased somewhat in the allowable current range. However, the temperature of PVC sheath rapidly increased to $128.1^{\circ}C$ in the 2 time allowable current range. This value is $10^{\circ}C$ higher than the temperature of PVC sheath on the metal screen cable, because the resistance of the carbon fiber is high and heat transfer rate is slow.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.10
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• pp.636-641
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• 2015

In this study, the partial discharge degradation properties for 2-core PVC cable($2cores{\times}1.5mm^2$ cross section, length of 10 cm, 20 cm, 30 cm) following immersion with the salt water that the 2%, 4%, 8% of NaCl is dissolved in 100 g of distilled water for 48 and 96 hours has been measured. The results of this study are as follows. When the degradation time in salt water of 2% NaCl is 48 hours, it found that the number of partial discharge increased as about 40 pps, 50 pps, 90 pps with increasing the length of cable to 10 cm, 20 cm, 30 cm. In case the concentration and degradation time is same, the inception and extinction voltage decreased with increasing the length of cable. When the degradation time in salt water is 96 hours and the length of cable is 20 cm, it found that the number of partial discharge decreased as 3,000 pps, 500 pps, 100 pps with increasing the concentration of NaCl to 2%, 4%, 8%.

• Proceedings of the KIEE Conference
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• 2008.10a
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• pp.167-168
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• 2008

The permeation of $Ca^{2+}$ ions through the materials such as polyvinyl chloride (PVC) and non-halogenated flame retardant cross linked polyolefin (FR-XLPO) used for CN-CV underground distribution power cable jackets was investigated. The permeation of $Ca^{2+}$ ions was found to increase with the increase of time. The FR-XLPO showed higher permeation of $Ca^{2+}$ ions, by a factor of about two, than the PVC. This was explained by the destruction of structural integrity caused by mixing a large amount of mineral flame retardant such as $Mg(OH)_2$ used to impart non-flame ability to the jacket material.

• Proceedings of the KIEE Conference
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• 1998.11c
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• pp.864-865
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• 1998

Permeation of $Ca^{2+}$ ions in PVC and flame-retardant polyolefin (FR) compounds for the sheath of medium voltage underground cables was studied. At $70^{\circ}C$ ion permeation increases fast at times of up to a few tens of hour and then at a relatively slow rate. The first fast increase was attributed to the diffusion of ions in the samples while the second slow increase of ion permeation was attributed to the permeation of $Ca^{2+}$ ions through the samples. It was also found that the diffusivity of $Ca^{2+}$ ions in FR compounds is much higher than that in PVC compounds.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1354-1356
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• 1994

In order to protect cable from rat's biting, a development of rodent repellent is described. This cable has double coated sheath such as construction of skin layer over the conventional cable sheath. Stabilized rodent repellent agent which has good compatibility with PVC is employed in a skin layer. Rodent repellent layer has highly residual properties of agent through the manufacturing process, and meets the general requirements of cable sheath. Also, rat repellent effect is excellent.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.4
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• pp.287-292
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• 2012

In this study, Multi-Channel Magnetic Flux Leakage(MFL) sensor - based inspection system was applied to monitor the condition of cables. This inspection system measures magnetic flux to detect the local faults(LF) of steel cable. To verify the feasibility of the proposed damage detection technique, an 8-channel MFL sensor head prototype was designed and fabricated. A steel cable bunch specimen with several types of damage was fabricated and scanned by the MFL sensor head to measure the magnetic flux density of the specimen. To interpret the condition of the steel cable, magnetic flux signals were used to determine the locations of the flaws and the level of damage. Measured signals from the damaged specimen were compared with thresholds set for objective decision making. In addition, the magnetic flux density values measured from every channel were summed to focus on the detection of axial location. And, sum of flux density were displayed with threshold. Finally, the results were compared with information on actual inflicted damages to confirm the accuracy and effectiveness of the proposed cable monitoring method.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.768-770
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• 1992

Conventional flame retardant cable using PVC or CR materials generate considerable amount of toxic and acidic gas (HCI etc.) together with excessive black smoke during a fire. The newly developed halogen free materials have dissolved the problem of halogen acid gases. This paer describes the development of this power cable insulation and sheath, using halogen free materals.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.244-247
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• 2002

In order to evaluate the water ingress to URD power cables with the jacketing materials and the cable structures, water vapor transmission (WVT) tests were carried out by the ASTM and the TEPCO's specification. All polyolefin compounds showed the superior water suppression to conventional PVC. Especially, linear polyethylenes have very low WVT. In case of cable structures, Allaminate cables showed the significant water suppression due to the watertight structure. Accordingly, it can be concluded that jacketing material and cable structure play an important role in the water suppression of URD power cables.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.8
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• pp.687-694
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• 2002

In order to replace the jacket material for URD power cables, the 6 kinds of polyethylene compounds were manufactured and evaluated. The characteristics of the compounds were investigated by water vapor transmission (WVT) test, thermal and mechanical test. In WVT test, all the polyethylene compounds showed the superior water resistance to conventional PVC. The molecular structure and density of polyethylene play an important role in WVT. Also, the polyethylene compounds showed the suitable characteristics in thermal and mechanical test. Especially, the linear polyethylene compounds showed the superior characteristics to LDPE ones. Due to the fillers in compounds, the abrasion resistance was decreased and the cut-through resistance was increased. From this study, it can be considered that the polyethylene compounds may be suitable to jacket material for URD power cables.