• Proceedings of the KIEE Conference
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• 2006.10a
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• pp.28-29
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• 2006

To improve Mechanical and Thermal Properties of semiconducting materials in power cable, we have investigated those of semiconducting materials showed by changing the content of carbon black and Carbon Nanotube. Density were measured by EW-200SG. High temperature, heat degradation initiation temperature, and heat weight loss were measured by TGA (Thermogravimetric Analysis). The dimension of measurement temperature was $0[^{\circ}C]$ J to $700[^{\circ}C]$, and rising temperature was $10[^{\circ}C/min]$. Heat degradation initiation temperature from the TGA results was decreased according to increasing the content of Carbon Nanotube. That is, heat stabilities of EVA containing the weak VA (vinyl acetate) against heat was measured the lowest. From the results of the experiment applied in this study, it is evident that a small amount of Carbon nanotube additives significantly improved the Mechanical and Thermal Properties of semiconducting materials.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.7
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• pp.598-606
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• 2000

In this paper we investigated the relation between the surface degradations and anti-pollution characteristics of Room Temperature Vulcanized(RTV) silicone rubber coating that has different roughness through immersing into saline water. We utilized several analytic techniques such as atomic force microscopy(AFM) scaning electron microscopy(SEM) contact angle Salt Deposit Density(SDD) and average leakage current under the condition of salt fog. It is found that the surface roughness of treated RTV silicone rubber increased and the hydrophobicity of sample surface decreased with increasing the duration o immersion into water due to the erosion of base polymer the melting down alumina trihydrate(ATH) and the diffusion of Low Molecular weight(LMW) fluid. Despite the roughness of surface had been increased by water immersion excellant anti-pollution and recovery characteristics were maintained and SDD saturated to 0.1~0.14mg/cm$^2$. The average leakage current under salt fog increased with surface roughness. Measurement of average leakage current will be helpful to investigate surface degradation and lifetime expectation of RTV silicone coating.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.133-137
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• 2004

In this paper, we investigated impurities content, absorption properties, and thermal properties showing by changing the content of carbon black which is semiconductive materials for underground power transmission. Specimens were made of sheet form with the three of existing resins and the nine of specimens for measurement. Impurities content of specimens and absorption properties were measured by ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometer) and Karl Fisher. And high temperature, heat degradation initiation temperature, and heat weight loss were measured by TGA (Thermogravimetric Analysis). The dimension of measurement temperature was 0$[^{\circ}]$ to 800$[^{\circ}]$, and rising temperature was 10$[^{\circ}/min]$. Impurities content was highly measured according to increasing the content of carbon black from this experimental result also absorption amount was increased according to these properties. Specially, impurities content values of the A1 and A2 of existing resins were measured more than 4000[ppm]. Heat degradation initiation temperature from the TGA results was decreased according to increasing the content of carbon black. All over, heat stabilities were EEA>EBA>pEVA. That is, heat stabilities of EVA containing the weak VA(vinyl acetate) against heat was measured the lowest.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.8
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• pp.641-646
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• 2011

Ga-doped ZnO-$SnO_2$ (ZSGO) films were deposited by rf magnetron sputtering and their structural and electrical properties were investigated. In order to fabricate the target for sputtering, the mixture of ZnO, $SnO_2$ (1:1 weight ratio) and $Ga_2O_3$ (3.0 wt%) powder was calcined at $800^{\circ}C$ for 1 h. The substrate temperature was varied from room temperature to $300^{\circ}C$. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The optical transmittances of the films were measured and the optical energy band gaps were obtained from the absorption coefficients. The resistivity variation with substrate temperature was measured. Auger electron spectroscopy was employed to find the atomic ratio of Zn, Sn, Ga and O in the film deposited at room temperature. ZSGO films exhibited the optical transmittance in the visible region of more than 80% and resistivity higher than $10\;{\Omega}cm$.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.213-213
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• 2000

Direct laser vaporization of transition-metal(Co, Ni)/graphite composite pellet produced single wall carbon naotubes(SWNT) in the condensing vapor in a heated flow cylinder-type tube furnace, Transition metal/graphite composite pellet target was made by mixing graphite, Co, and Ni in 98:1:1 atomic weight ratios, pressing the mixed powder, and curing it. The target was placed in a tube furnace maintained at 1200$^{\circ}C$ and Ar inert collision gas continuously flowed into the tube. The 2nd harmonic, 532nm wavelength light from Nd-YAG laser was used to vaporize the tube. The carbon nanotubes produced by the laser vaporization were accumulated on quartz tube wall. The raw carbon nanotube materials were purified with surfactants(Triton X-100) in a ultrasonicator. These carbon nanotubes were analyzed using SEM, XRD, and Raman spectroscopic method. The carbon nanotube growth on the Ni-patterned Si substrate was investigated by the CVD process. Transition-metal, Ni and CH4 gas were used as a catalyst and a reactant gas, respectively. The structure and the phonon frequencies of the carbon nanotubes formed on the patterned Si substrate were measured by SEM and Raman spectrometer.

• Macromolecular Research
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• v.17 no.11
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• pp.894-900
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• 2009

This study examined the charge carrier photogeneration and hole transport properties of blends of poly (9-vinylcarbazole) (PVK), $\pi$-conjugated polymer, with different weight proportions (0~29.4 wt%) of (PEA)$VOPO_4{\cdot}H_2O$ (PEA: phenethylammonium cation), a novel organic-inorganic hybrid material, using IR, UV-Vis, and energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), steady state photocurrent (SSPC) measurement, and atomic force microscopy (AFM). The SSPC measurements showed that the photocurrent of PVK was reduced by approximately three orders of magnitude by the incorporation of a small amount (~12.5 wt%) of (PEA) $VOPO_4{\cdot}H_2O$, suggesting that hole transport occurred through the PVK carbazole groups, whereas a reverse trend was observed at high proportions (>12.5 wt%) of (PEA)$VOPO_4{\cdot}H_2O$, suggesting that transport occurred via (PEA)$VOPO_4{\cdot}H_2O$ molecules. The transition to a trap-controlled hopping mechanism was explained by the difference in ionization potential and electron affinity of the two compounds as well as the formation of charge percolation threshold pathways.

• Nuclear Engineering and Technology
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• v.54 no.3
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• pp.1049-1061
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• 2022

Neutron and gamma-ray shielding properties of Inconel 718 reinforced B₄C (0-25 wt%) were investigated using PSD software. Mean free path (MFP), linear and mass attenuation coefficients (LAC,MAC), tenth-value and half-value layers (TVL,HVL), effective atomic number (Z_eff), exposure buildup factors (EBF), and fast neutron removal cross-sections (FNRC) values were calculated for 0.015-15 MeV. It was found that MAC and LAC increased with the decrease in the content of B₄C compound by weight in Inconel 718. The EBFs were computed using G-P fitting method for 0.015-15 MeV up to the penetration depth of 40 mfp. HVL, TVL, and FNRC values were found to range between 0.018 cm and 3.6 cm, between 2.46 cm and 12.087 cm, and between 0.159 cm^-1 and 0.194 cm^-1, respectively. While Inconel 718 provides the maximum photon shielding property since it offered the highest values of MAC and Z_eff and the lowest value of HVL, Inconel 718 with B₄C(25 wt%) was observed to provide the best shielding material for neutron since it offered the highest FNRC value. The study is original in terms of several aspects; moreover, the results of the study may be used in nuclear technology, as well as other technologies including nano and space technologies.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.101-102
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• 2022

A new hydrazone derivatives namely (E)-N'-(4-(dimethylamino)benzylidene)-2-(5-methoxy-2-methyl-1H-indol-3-yl)acetohydrazide (HIND) has been confirmed for mitigating the corrosion of the steel rebar exposed to chloride contaminated synthetic concrete pore solution (ClSCPS). The mitigation of corrosion properties has been characterized by weight loss and electrochemical methods (Electrochemical impedance, Potentiodynamic polarization studies) as well as surface observations. The presence of HIND in the ClSCPS decreased the corrosion of steel rebar by adsorption of HIND molecules on the surface of the steel rebar. The optimal HIND concentration was 0.5 mmol/L, corresponding to an inhibition efficiency of 88.4%. The use of HIND enables the corrosion process to have a higher energy barrier. X-ray photo electron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) spectroscopy interpretations confirmed that HIND mitigates the corrosion attack on the surface steel rebar.

• Korean Journal of Environmental Biology
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• v.24 no.2 s.62
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• pp.102-111
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• 2006

The increased occurrence of hyperglycemia and oxidative stress in streptozotocin (STZ) induced type I diabetes has been implicated in the etiology and pathology of disease complication. STZ has known to be genotoxic in a variety of assays including tests for microbial mutagenesis and unscheduled DNA synthesis in rat kidney. Diabetes mellitus (DM) is a pathologic condition, resulting in severe metabolic imbalances and non-physiologic changes in many tissues. We examined the effect of gamma radiation and KWNP on preventing the development of insulin dependent diabetes mellitus using streptozotocin-induced Fisher 344 diabetic rats. The hematological values (red blood cell and white blood cell), serum biochemical constituents-alkaline phosphatase (ALP), total cholesterol, triglycerides and insulin-were checked and the organs (testis, spleen and kidney) were weighed. The gonad indices of the STZ treated groups were much lower than the value of the control group. But the gonad indices of the KWNP treated groups were higher than those of the treated groups. The ratio of the weight of kidney to the body weight of the STZ treated groups was higher than that of the control group. The value of the diabetic group treated with KWNP after irradiation (F group) was lower than the other STZ treated groups. The white blood cell and ALP values of the F group were lower than the other STZ groups, as well. The cholesterol and triglyceride values of all the KWNP treated groups were significantly lower than the other groups. A significant increase (about 10 times) of insulin was detected in the F group. The results of hematological assay showed the distinctive damage in the irradiated and STZ treated groups. The quantity of apoptotic cells in seminiferous tubule of testis confirmed a serious damage as assessed in the STZ treated groups. These experimental results have revealed that treatment of the products of KWNP after irradiation has the antidiabetic effect in the STZ-induced diabetic rats. But the F group showed higher recuperative power. These experimental results have revealed that treatment of the gamma irradiation and KWNP have the recovering effect in the STZ-induced diabetic rats.

• Journal of Energy Engineering
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• v.17 no.1
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• pp.15-22
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• 2008

This study was carried out to investigate physical and chemical characteristics of the distillates and residue of Athabasca oilsand bitumen obtained from Canada, using a vacuum distillation unit. The distillates and residue produced from the vacuum distillation were characterized through atomic analysis, SARA analysis, and measurement of boiling point distribution, molecular weight, and API gravity. The vacuum distillation equipment consisted of a 6-litter volume vessel, a glass-packed column, a condenser, a reflux device, a flask fer collecting distillates, and a temperature controller. The cutting of distillates was performed with four steps under the condition of full vacuum and maximum temperature of $320^{\circ}C$. The results showed that the sulfur amount and average molecular weight of the distillates were significantly reduced compared to those of oilsand bitumen. As the cutting temperature increased, the hydrogen amount decreased but the sulfur amount and average molecular weight increased in the distillates.