• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.853-854
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• 2006

Warm compaction powder metallurgy was used to produce a $Ti_3SiC_2$ particulate reinforced Cu matrix composite. Fabrication parameters and warm compaction behaviors of Cu powder were studied. Based on the optimized fabrication parameters a Cu-based electrical contact material was prepared. Results showed that in expend of some electrical conductivity, addition of $Ti_3SiC_2$ particulate increased the hardness, wear resistivity and anti-friction ability of the sintered Cu-base material.

• Journal of architectural history
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• v.24 no.5
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• pp.49-58
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• 2015

The purpose of this study is to analyze the overall condition of the foundation for the three storied stone pagoda of Bulguksa temple in GyeongJu. As a research method, exploration of the electrical resistivity, refraction seismic, surface wave exploration, GPR exploration, Reputation loading test. The results of the investigation, the range of the foundation was formed in foundation stone outskirts of 1.5 ~ 2.0m. It was confirmed to be about 2.0m depth. The depth of the foundation becomes shallower from the base portion to the outside. And the bearing capacity of foundation was sufficient conditions to weight. It can sufficiently support the weight of pagoda. And, the result of this investigation becomes basis data for repair work.

• Corrosion Science and Technology
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• v.5 no.3
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• pp.106-111
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• 2006

Painting has protected metallic stack but the paint films may be degraded and corrosion problem can be arisen. To protect the painted metal stack, cathodic protection can be applied. If cathodic protection is applied to bare metal, only small area may be protected. However, if cathodic protection is applied to painted metal surface, large area can be protected and the lifetime of paint films can be extended. High corrosion resistant alloys were corroded at a Flue Gas Desulfurization (FGD) facility of power plant within a short period and thus cathodic protection can be used to protect these metals. On the base of computer simulation, if cathodic protection is applied to bare metal in a FGD environment, it was estimated that applied current could almost be spent to protect area near the anode. However, if cathodic protection is applied to high resistant-coated metal, the much larger area from the anode could be effectively protected.

• Proceedings of the KIEE Conference
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• 1987.07a
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• pp.501-504
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• 1987

The photoconductor is made of evaporated amorphous selenium as the base material, doped with arsenic and tellurium to prevent crystallization and to increase the red sensitivity of the amorphous selenium. The four-layered photoconductor of Se-As-Te has good photosensitivity(r=0.9) and high dark resistivity($P_d=10^{12}{\Omega}{\cdot}cm$). therefore, this four-layered photoconductor can be used for the target of color image pick-up tube.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.7
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• pp.6-13
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• 2006

Tin doped indium oxide(ITO) and Al doped zinc oxide(ZnO:Al) films, which are widely used as a transparent conductor in optoelectronic devices, were prepared by using the capacitively coupled DC magnetron sputtering method. ITO and ZnO:Al films with the optimum growth conditions showed each resistivity of $1.67{\times}10^{-3}[{\Omega}-cm],\;2.2{\times}10^{-3}[{\Omega}-cm]$ and transmittance of 89.61[%], 90.88[%] in the wavelength range of the visible spectrum. The two types of 5 inch-PDP cells with ZnO:Al and ITO transparent electrodes were made under the same manufacturing conditions. The PDP cell with ZnO:Al film was optimally operated in the mixing gas rate of Ne(base)-Xe(8[%]), and at gas pressure of 400[Torr]. It also shows the average measured brightness of $836[cd/m^2]$ at voltage range of $200{\sim}300$[V]. Luminous efficiency, one of the key parameter for high brightness and low power consumption, ranges from 1.2 to 1.6[lm/W] with increasing frequency of ac power supplier from 10 to 50[Khz]. The brightness and luminous efficiency are lower than those with ITO electrode by about 10[%]. However, these values are considered to be enough for the normal operation of PDP TV.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.7
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• pp.574-577
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• 2011

In this study, we use the $2.5cm{\times}7.5cm$ soda lime glass as the substrate. We used the ultrasonicator. Glass was dipped in the acetone, methanol and DI water respectively for 10 minutes. Ar(99.99%)gas was used as the sputtering gas. We varied the RF power between 100~175 W with 25 W steps. Base pressure was kept by turbo molecular pump at $3.0{\times}10^{-6}$ torr. Working pressure was kept by injection of Ar gas. ZnS thin films were deposited with the radio frequency magnetron sputtering technique at various temperatures and sputtering powers. It is also clearly observed that, the intensity of the (111) XRD peak increases with increasing the RF power. Electrical properties were measured by hall effect methods at room temperature. The resistivity, carrier concentration, and hall mobility of ZnS deposited on glass substrate as a function of sputtering power. It can be seen that as the sputtering power increase from 100 to 175 W, the resistivity of the films on glass decreased significantly from $8.1{\times}10^{-2}$ to $1.2{\times}10^{-3}\;{\Omega}{\cdot}cm$. This behavior could be explained by the effect of the sputtering power on the mobility and carrier concentration. When the RF power increases, the carrier concentration increases slightly while the resistivity decreases significantly. These variation originate from improved crystallinity and enhanced substitutional doping as the sputtering power increases.

• Applied Chemistry for Engineering
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• v.4 no.2
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• pp.393-402
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• 1993

Redox flow secondary battery have been studied actively as one of the most promising electrochemical energy storage devices for a wide range of applications, such as electric vehicles, photovoltaic arrays, and excess power generated by electric power plants. In all-vanadium redox flow battery using solution of vanadium-sulfuric acid as a active material, the difficulty in developing an efficient ion selective membrane can still be identified. The asymmetric cation exchange membrane(M-30) as a separator of all-vanadium redox flow battery which were obtained by the reaction of chlorosulfonation for 30 minutes under the irradiation of UV, showed its superiority in the transport number of 0.94 and electrical resistivity of $0.5{\Omega}{\cdot}cm^2$. The base membrane were prepared by lamination a low density polyethlene film of $10{\mu}m$ thickness on polyolefin membrane(HIPORE 120). The electrical resistivity of M-30 membrane in real solution of vanadium-sulfuric acid was $3.79{\Omega}{\cdot}cm^2$ and it was similar to that of Nafion 117 membrane. Also the cell resistivity was $6.6{\Omega}{\cdot}cm^2$and lower than that of Nafion 117. In considertion of electrochemical properties and costs of membranes, M-30 membrane was better than that of Nafion 117 and CMV of Asahi glass Co. as a separator of all-vanadium redox flow battery.

• Journal of the Korean Geophysical Society
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• v.3 no.2
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• pp.113-126
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• 2000

We have conducted multiple geophysical surveys to investigate the geoenvironmental change of the Nanjido Landfill due to the stabilization process. Geophyscial surveys are comprized of gravity, magnetic, dipole-dipole electrical and SP methods. Due to the field conditions, surveys were conducted on the top surface of the landfill no.2 and southern border areas in front of landfills. The gravity anomalies obtained on the top surface of the landfill no.2 in 1999 show that the gradient of the anomaly on the central area is decreasing in comparison with that observed four years ago. The complexity of magnetic anomaly pattern it also decreasing. These facts suggest that the stabilization work of the Nanjido landfill makes some progress by compaction process due to repetitive subsidence and refilling. The dipole-dipole electrical resistivity and SP data obtained on the outside of the waterproof wall at the landfill no.1 were severely affected by unsatisfactory surface conditions. On the other hand, the dipole-dipole electrical resistivity profiles obtained on the inside and outside parts of the waterproof wall at the landfill no.2 show the blocking effect of leachate flow by the waterproof wall. Few SP anomalies are observed on the top and side surfaces of the landfill no.2, but SP anomalies obtained on the base area inside the waterproof wall strongly reflect the effect of leachate collecting wells.

• Computers and Concrete
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• v.32 no.3
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• pp.287-302
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• 2023

Corrosion of reinforcing bars in reinforced concrete structures due to chloride attack in environments containing chloride ions is one of the most important factors in the destruction of concrete structures. According to the abundant reports that the corrosion rate around the repair area has increased due to the macro-cell current known as the incipient anode, it is necessary to understand the effective parameters. The main objective of this paper is to investigate the effect of the kinetic parameters of corrosion including the cathodic Tafel slope, exchange current density, and equilibrium potential in repair materials on the total corrosion rate and maximum corrosion rate in the patch repair system. With the numerical simulation of the patch repair system and concerning the effect of parameters such as electromotive force (substrate concrete activity level), length of repair area, and resistivity of substrate and repair concrete, and with constant other parameters, the sensitivity of the macro-cell current caused by changes in the kinetic parameters of corrosion of the repairing materials has been investigated. The results show that the maximum effect on the macro-cell current values occurred with the change of cathodic Tafel slope, and the effect change of exchange current density and the equilibrium potential is almost the same. In the low repair extant and low resistivity of the repairing materials, with the increase in the electromotive force (degree of substrate concrete activity) of the patch repair system, the sensitivity of the total corrosion current reduces with the reduction in the cathode Tafel slope. The overall corrosion current will be very sensitive to changes in the kinetic parameters of corrosion. The change in the cathodic Tafel slope from 0.16 to 0.12 V/dec and in 300 mV the electromotive force will translate into an increase of 200% of the total corrosion current. While the percentage of this change in currency density and equilibrium potential is 53 and 43 percent, respectively. Moreover, by increasing the electro-motive force, the sensitivity of the total corrosion current decreases or becomes constant. The maximum corrosion does not change significantly based on the modification of the corrosion kinetic parameters and the modification will not affect the maximum corrosion in the repair system. Given that the macro-cell current in addition to the repair geometry is influenced by the sections of reactions of cathodic, anodic, and ohmic drop in repair and base concrete materials, in different parameters depending on the dominance of each section, the sensitivity of the total current and maximum corrosion in each scenario will be different.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.28 no.1
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• pp.51-56
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• 2015

The object of this study is to obtain the optimum mix proportion of halogen free compound with flame resistance and, for the purpose, thermal/electrical characteristics test are conducted using compatibilizing agents, flame resistance agents, hydroxide aluminum, sunscreen, antioxidant and silicon oil on the base resin of linear low density polyethylene (LLDPE), Ethylene vinyl acetate copolymer (EVA). Existing compound method accompanies many requirements to be satisfied including a lot of addition of flame resistance agents, prohibition of impact on mixing capability with base and property and etc. In this study, different from the existing method, the optimum mix proportion is determined and experimented by adding nano clay. Oxygen index test shows no difference between specimens while T-6, T-9 shows oxygen index of 29[%] and 26[%], respectively. This is concluded that hydroxide aluminum, which is a flame resistance agent, leads low oxygen index. From UL94-V vertical flame resistance test, the combustion behavior is determined as V-0, Fail based on UL94-V decision criteria. Viscometry shows low measurements in specimens with separate addition of compatibilizing agents or nano clay. Volume resistivity test shows low measurement mainly in specimens without compatibilizing agents. Therefore, with the flame resistance compound shows better performance for thermal/electrical property and the optimum mix proportion are achieved among many existing materials.