• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1343-1344
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• 2007

In this paper, we investigated mechanical characteristics about thermal properties in semiconductor layer of power cables. Method of specimen making used solution mixing and Tensometer 2000 of Alpha used for measurement of stress and strain. Semiconductor layer made an experiment on separately environmental temperature$[25^{\circ}C]$ and high temperature$[90^{\circ}C]$ which running temperature$[90^{\circ}C]$ of cables exposed. As a result, specimen of applicable DFS(Dual Filler System) could know mechanical superiority that its structural characteristics reinforcement considered thermal characteristics.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.156-157
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• 2006

To improve mean-life and reliability of power cable in this study, we have investigated chemical properties showing by changing the content of Carbon nanotube(CNT) that is semiconductive additives for underground power transmission. Specimens were made of sheet form with the three of existing resins and the five of specimens for measurement. Chemical properties of specimens was measured by FT-ATR (Fourier Transform Attenuated Total Reflectance). The condition of specimens was a solid sheet. We could observe functional group (C=O, carbonyl group) of specimens through FT-ATR. From these experimental result, the concentration of functional group (C=O) was high according to increasing the content of Carbon nanotube. We could know CNT/EEA was excellent more than other specimens from above experimental results.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.134-135
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• 2005

To improve mean-life and reliability of power cable, we have investigated volume resistivity and thermal conductivity showed by changing the content of acetylene black which is the component parts of semiconductive shield in underground power transmission cable. The sheets were primarily kneaded in their pellet form material samples for 5 minutes on rollers ranging between 70[$^{\circ}C$] and 100[$^{\circ}C$]. Then they were produced as sheets after pressing for 20 minutes at 180[$^{\circ}C$] with a pressure of 200[kg/cm]. The content of conductive acetylene black was the variable, and their contents were 20, 30 and 40[wt%], respectively. Volume resistivity of specimens was measured by volume resistivity meter after 10 minutes in the preheated oven of both $25\pm1[^{\circ}C]$ and $90\pm1[^{\circ}C]$. Thermal conductivity was measured by Nano Flash Diffusivity. The measurement temperatures of thermal conductivity using Nano Flash Diffusivity were both 25[$^{\circ}C$] and 55[$^{\circ}C$]. From these experimental results, volume resistivity was high according to an increase of the content of acetylene black. And thermal conductivity was increased to an increase of the content of acetylene black. And thermal conductivity were increased by heating rate because volume of materials was expanded according to rise in temperature.

• Transactions on Electrical and Electronic Materials
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• v.7 no.1
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• pp.16-20
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• 2006

In this paper, we investigated the effects of short-term oxygen plasma treatment of semiconducting silicone layer to improve interfacial performances in joints prepared with a insulating silicone materials. Surface characterizations were assessed using contact angle measurement and x-ray photoelectron spectroscopy (XPS), and then adhesion level and electrical performance were evaluated through T-peel tests and electrical breakdown voltage tests of treated semi-conductive and insulating joints. Plasma exposure mainly increased the polar component of surface energy from $0.21\;dyne/cm^2$ to $47\;dyne/cm^2$ with increasing plasma treatment time and then leveled off. Based on XPS analysis, the surface modification can be mainly ascribed to the creation of chemically active functional groups such as C-O, C=O and COH on semi-conductive silicone surface. This oxidized rubber layer is inorganic silica-like structure of Si bound with three to four oxygen atoms ($SiO_x,\;x=3{\sim}4$). The oxygen plasma treatment produces an increase in joint strength that is maximum for 10 min treatment. However, due to brittle property of this oxidized layer, the highly oxidized layer from too much extended treatment could be act as a weak point, decreasing the adhesion strength. In addition, electrical breakdown level of joints with adequate plasma treatment was increased by about $10\;\%$ with model samples of joints prepared with a semi-conducting/ insulating silicone polymer after applied to interface.

• Transactions on Electrical and Electronic Materials
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• v.10 no.6
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• pp.217-221
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• 2009

The use of the carbon nanotube (CNT) is superior to the general powder state materials in their thermal and chemical properties. Because its ratio of diameter to length (aspect ratio) is very large, it is known to be a type of ideal nano-reinforcement material. Based on this advantage, the existing carbon black of the semiconductive shield materials used in power cables can acquire excellent properties by the use of a small amount of CNTs. Therefore, we fabricated specimens using a solution mixing method. We investigated the thermal properties of the CNT, such as its storage modulus, loss modulus, and its tan delta using a dynamic mechanical analysis 2980. We found that a high thermal resistance level is demonstrated by using a small amount of CNTs. We also investigated the chemical properties of the CNT, such as the oxidation reaction by using Fourier transform infrared spectroscopy (FT-IR) made by Travel IR. In the case of the FT-IR tests, we searched for some degree of oxidation by detecting the carboxyl group (C=O). The results confirm a tendency for a high cross-linking density in a new network in which the CNTs situated between the carbon black constituent molecules show a bond using similar constructive properties.

• Korean Journal of Materials Research
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• v.32 no.5
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• pp.264-269
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• 2022

Ti₃C₂T_x MXene, which is a representative of the two-dimensional MXene family, is attracting considerable attention due to its remarkable physicochemical and mechanical properties. Despite its strengths, however, it is known to be vulnerable to oxidation. Many researchers have investigated the oxidation behaviors of the material, but most researches were conducted at high temperatures above 500 ℃ in an oxidation-retarding environment. In this research, we studied changes in the structural and electrical properties of Ti₃C₂T_x MXene induced by low-temperature heat treatments in ambient conditions. It was found that a number of TiO₂ particles were formed on the MXene surface when it was mildly heated to 200 ℃. Heating the material to higher temperatures, up to 400 ℃, the phase transformation of Ti₃C₂T_x MXene to TiO₂ was accelerated, resulting in a TiO₂/Ti₃C₂T_x hybrid. Consequently, the metallic nature of pure Ti₃C₂T_x MXene was transformed to semiconductive behavior upon heat-treating at ≥ 200 ℃. The results of this research clearly demonstrate that Ti₃C₂T_x MXene may be easily oxidized even at low temperatures once it is exposed to air.

• Journal of the Korean institute of surface engineering
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• v.51 no.4
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• pp.231-236
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• 2018

We report p-type electrical characteristics of the amorphous $La_2NiO_{4+{\delta}}$ thin films which were sputtered on the glass substrates using an RF sputtering system. As-deposited thin films at room temperature and $300^{\circ}C$ were amorphous in nature. Post-annealing of the thin film samples over $400^{\circ}C$ resulted in the nano-crystallization of the $La_2NiO_{4+{\delta}}$. The electrical properties of the films were much dependent on the oxygen partial pressure, temperature of the post-annealing and sputtering ambient. The as-deposited samples at room temperature show a hole concentration of $7.82{\times}10^{13}cm^{-3}$, and it could be increased as high as $3.51{\times}10^{22}cm^{-3}$ when the films were post-annealed in an oxygen atmosphere at $500^{\circ}C$. Such p-type conductivity behavior of the $La_2NiO_{4+{\delta}}$ films suggests that the amorphous and nano-crystallized $La_2NiO_{4+{\delta}}$ films have potential for the application as p-type semiconductive or conductive materials at low temperatures where material diffusion is limited.