• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.5
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• pp.559-566
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• 2016

Cables for Towed Array Sonar System(TASS) were developed. In order to verify the performance of cables, environmental and operational conditions as well as functional requirements were investigated during design stage. Double armored high and low voltage integrated cable for towed body and two kinds of cables, armored and light weight power and optic hybrid cables for towed array sensor system were developed by modeling and simulation. Customized manufacturing process and test method, such as foam extrusion and dynamic fatigue test were applied to this development. In conclusion, underwater towed hybrid cable with high tensile strength and compact structure were developed.

• Progress in Superconductivity and Cryogenics
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• v.25 no.2
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• pp.19-24
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• 2023

Recently, interest in renewable energy such as solar and wind power has increased as an alternative to fossil fuels. Renewable energy sources such as large wind farms require long-distance power transmission because they are located inland or offshore, far from the city where power is required. High-Temperature Superconducting (HTS) power cables have more than 5 times the transmission capacity and less than one-tenth the transmission loss compared to the existing cables of the same size, enabling large-capacity transmission at low voltage. For commercialization of HTS power cables, unmanned operation and long-distance cooling technology of several kilometers is essential, and pressure drop characteristic is important. The cryostat's spiral corrugation tube is easier to bend, but unlike the round tube, the pressure drop cannot be calculated using the Moody chart. In addition, it is more difficult to predict the pressure drop characteristics due to the irregular surface roughness of the binder wound around the cable core. In this paper, a CFD model of a spiral corrugation tube with a core was designed by referring to the water experiments from previous studies. In the four cases geometry, when the surface roughness of the core was 10mm, most errors were 15% and the maximum errors were 23%. These results will be used as a reference for the design of long-distance HTS power cables.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3201-3204
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• 2000

In general, analog tester or strip chart recorder have been used to measure the corrosion potential of structures such as gas pipelines, oil pipelines, hot water pipelines, power cables etc. Recently, automatic digital data logger substitutes for these manual equipment because using these manual equipments are tedious and time consuming. However, digital data logger also has a shortcoming, that is, short measuring time because of the short lifetime of batteries. Therefore, we developed a long lifetime and low power loss battery taking advantage of galvanic series. In this paper, the results of development for power generator using two metals and DC/DC converter in order to obtain enough voltage for the operation of digital data logger. DC/DC converter operates with 0.5[V]. Its output voltage is 3.5[V] and output current is from 60[mAh] to 1,200[mAh].

• The Transactions of The Korean Institute of Electrical Engineers
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• v.65 no.10
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• pp.1780-1785
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• 2016

This paper presents few case studies of state diagnosis of XLPE cables using very low frequency techniques. The power cables of 22.9kV which have installation fault were assessed using VLF technique in addition to other techniques like insulation resistance and DC voltage withstand test. From the experimental results, The dielectric loss($tan{\delta}$) values of degradation of the cable(joint, knife, needle) at $U_0$ were 5.839, 5.526 and 6.251, respectively and all values were "further study advised". VLF PD measurement was also found defective portion. These method was effective in defect to fault in the degradation of the cable. However, the breakdown did not occur in the degradation of the cable because of properties of XLPE insulation. Few case studies of using VLF $tan{\delta}$ diagnosis for fault are measured and analyzed. The $tan{\delta}$ values at $U_0$ were "further study advised" or "action required".

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.3
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• pp.191-195
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• 2015

Inside the existing superconducting cables, the superconducting wire carries a loss-free current, and the cable former (the stranded copper wire) bypasses the fault current to prevent damage and loss of the superconducting cable when the fault current is applied. The fault-current-limiting-type superconducting cable proposed in this paper usually carries a steady current; but in a fault state, the cable generates self-resistance that makes the fault current lower than a certain width. That is, the superconducting cable that transmitted only a low voltage and a large capacity power repetitively limits the fault current, as does a superconducting current limiter. To complete this structure, it is essential to investigate the mutual resistance relationship between the superconducting wires after applying a fault current. Therefore, in this paper, one kinds of superconducting wires (a wire without a stabilization layer) were connected parallel 4 tapes, respectively; and after applying a fault current, the current, voltage, resistance and thermal stability of the HTS thin-film wires were examined.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.1
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• pp.91-96
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• 2004

Overloading of electrical equipment results in excessive currents. As the heat developed in the cables is proportional to square of the current, they get overheated. The insulation on cables is generally made of materials which are damaged easily by excessive temperature. They may therefore lose their insulating properties and lead to short circuits. Since many insulating materials are combustible, they may even catch fire if the temperature rises to their ignition temperature. In this paper, we have simulated the thermal analysis for cable according to the value of current in a overload and a short with the cable of the L's company product(600 V, VV : Four Core) using the electro-thermal finite element method(Flux2D).

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.7
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• pp.91-96
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• 2014

The requirements for separation between ICT cables and power cables depend upon the electromagnetic immunity of the ICT cable, the construction of the power cable, the quantity of, and type of electrical circuits and the presence of dividers etc. We studied and reviewed the regulations and standards relevant for requirements of this separation in domestic and foreign. And then we would like to suggest the method of separation calculation between ICT and power cabling taking the EMC into consideration.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.3
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• pp.498-504
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• 2015

This paper proposed an Spread Spectrum Time Domain Reflectometry (SSTDR) using time-frequency correlation analysis in order to have more accurate fault determination and location detection than classical SSTDR despite increased signal attenuation due to the long distance to cable fault location. The proposed method was validated through comparison with classical SSTDR methods in open- and short-circuit fault detection experiments of low-voltage power cables. The experimental results showed that the proposed method can detect correlation coefficients at fault locations accurately despite reflected signal attenuation so that cable faults can be detected more accurately and clearly in comparison to existing methods.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.1
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• pp.36-42
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• 2011

This paper mainly proposes the protective coordination scheme of the microgrid system. The microgrid protection is identical to the conventional protection system separating the normal part and contingency part to reduce damage when the contingency occur at power cables, facilities. But they are different in the protection type. The conventional protection system only considers unidirectional current. However the microgrid protection should be considered not only unidirectional current but also backfeed current because various microsources and loads are installed in the microgrid system. In case the contingency occurs in microsource, when microgrid is interconnected to grid, the protection system should be configured to not separate microgrid from grid before the microsource is isolated to microgrid. And in case of fault occur in power system, the microsources should not isolated to microgrid before the static switch at PCC is tripped to separate from power system. Considering these characteristic of microgird, this paper proposes the protective coordination scheme of microgrid and implemented the on-line real time monitoring system. Especially in case the microgrid is connected to low voltage distribution system with 220/380V voltage level, the proposed protection method with power IT technology can solve the problems when the existing protective devices only applied to the microgrid system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.593-602
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• 2020

Power cables installed in domestic factories or underground can cause accidents depending on the manufacturing process, installation, and environmental conditions during use. When an accident occurs in a power cable, it can cause enormous economic loss and social confusion. Hence, the importance of preventive management of the cable through diagnosis is increasing to prevent it. Therefore, in this paper, a diagnostic sample cable was produced by simulating a part that could be a problem due to the installation, manufacturing defects, or deterioration of cables that can occur in the field. Dielectric loss Tangent (tan 𝛿; TD), and Partial Discharge(PD) tests were performed. Partial discharge and AC (60Hz) withstand voltage equipment using High-Frequency Current Transformer (HFCT) were applied After applying a VLF (Very Low Frequency) power supply with a frequency of 0.1Hz was applied. As a result, B and C phase defect samples at a 2.0U₀ voltage through the VLF could measure the internal partial discharge in the A-phase normal sample cable from the noise at a 0.5U₀ to 2.0U₀ voltage. In addition, the 1.5U₀ voltage was measured through the AC (60Hz) withstand voltage equipment of the commercial frequency to verify its effectiveness. Partial discharge in the run-off state was measured at a voltage of 1.0U₀, and there was a risk when installing the equipment. AC power equipment showed a difficulty of movement by volume or weight. The diagnostic method, through the VLF of the quadrant state, revealed its safety and effectiveness.