• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.201-203
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• 2001

Safety is emphasized in nuclear power plant system for its characteristic. One of the most important systems to guarantee the safety of nuclear power plant is the PPS(Power protection system). The measurement control system includes PPS, which is similar to the human nervous system, is very important factor not only for the safety but also for the operation. Therefore, developing a technology to level up the performance of measurement system and reliability of the plant will bring cost-effective and safe generation of nuclear power. In this study, I researched composition of digitized PPS and algorithm for cyclic inspection.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.96-101
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• 2001

The development of a new experimental method is required to easily observe the growth behavior of fatigue cracks. To satisfy the requirement, an image processing technique was introduced to fatigue testing. The length of surface fatigue crack could be successfully measured by the image processing system. At first, the image data of cracks were stored into the computer while the cyclic loading was interrupted. After testing, crack length was determined using image processing software which was developed by ourselves. Block matching method was applied to the detection of surface fatigue cracks. By comparing the data measured by image processing system with the data measured by manual measurement with a microscope, the effectiveness of the image processing system was established. If the proposed method is used to monitor and observe the crack growth behavior automatically, the time and efforts for fatigue test could be dramatically reduced.

• Journal of the Korean Society of Safety
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• v.17 no.4
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• pp.11-18
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• 2002

We proposed a new experimental method which is required to easily observe the growth behavior of fatigue cracks. In the proposed method, the image data of cracks were stored into the computer while the cyclic loading was interrupted. After testing, crack length was determined using an image processing software which was developed by authors. By comparing the data measured by the image processing system with those by the manual measurement with a microscope, the effectiveness of the image processing system was established. If the proposed method is used to monitor and observe the crack growth behavior automatically, the time and efforts for fatigue test could be dramatically reduced.

• Journal of the Korean Society for Nondestructive Testing
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• v.30 no.5
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• pp.444-450
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• 2010

In the present study, the microscopic degradation of copper and copper alloy subjected to cyclic deformation has been evaluated by the electrical resistivity measurement using the DC four terminal potential method. The copper (Cu) and copper alloy (Cu-35Zn), whose stacking fault energy is much different each other, were cyclically deformed to investigate the response of the electrical resistivity to different dislocation substructures. Dislocation cell substructure was developed in the Cu, while the planar array of dislocation structure was developed in the Cu-35Zn alloy increasing dislocation density with fatigue cycles. The electrical resistivity increased rapidly in the initial stage of fatigue deformation in both materials. Moreover, after the fatigue test it increased by about 7 % for the Cu and 6.5 % for the Cu-35Zn alloy, respectively. From these consistent results, it may be concluded that the dislocation cell structure responds to the electrical resistivity more sensitively than the planar array dislocation structure evolved during cyclic fatigue.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1795-1799
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• 2013

The corrosion property of aluminum by lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt is investigated in liquid and gel electrolytes consisting of ethylene carbonate/propylene carbonate/ethylmethyl carbonate/diethyl carbonate (20:5:55:20, vol %) with vinylene carbonate (2 wt %) and fluoroethylene carbonate (5 wt %) using conductivity measurement, cyclic voltammetry, scanning electron microscopy, and energy dispersive X-ray spectroscopy. All corrosion behaviors are attenuated remarkably by using three gel electrolytes containing 3 wt % of hydrophilic and hydrophobic fumed silica. The addition of silica particles contributes to the increase in the ionic conductivity of the electrolyte, indicating temporarily formed physical crosslinking among the silica particles to produce a gel state. Cyclic voltammetry also gives lower anodic current responses at higher potentials for repeating cycles, confirming further corrosion attenuation or electrochemical stability. In addition, the degree of corrosion attenuation can be affected mainly by the electrolytic constituents, not by the hydrophilicity or hydrophobicity of silica particles.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.2
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• pp.100-106
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• 2008

An experimental study was carried out in a small-scale test furnace to investigate the performance, such as $NO_X$ emission, enhancement of heat transfer, uniformity of temperature, and etc, of oscillating combustion applied in radiant tube burner system. A premixed type burner and a cyclic oscillating control valve were designed and used. The fuel, used commercial LPG in this study, was only oscillated using the cyclic oscillating control valve. As oscillating combustion was applied in radiant tube burner system, it is found that $NO_X$ emission, compared to no oscillation, could be reduced by 38% at $90{\sim}120rpm\;(1.5{\sim}2.0Hz)$. However, as oscillating frequency was increased, effect of abatement of $NO_X$ emission is gradually reduced. From the measurement of furnace heating time from $100^{\circ}C$ to $720^{\circ}C$, heat transfer is increased by 11.5% at the oscillation of 120rpm. Temperature distribution of radiant tube surface is more uniform at oscillation of 120rpm with decrease of the peak temperature and increase of low temperature. From these results, it is confirmed that oscillating combustion is useful in radiant tube burner system.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.6
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• pp.540-546
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• 2010

In order to confirm the effect of Nafion ionomer content in catalyst layer on the performance of PEMFC, we have fabricated several electrodes which were prepared by varying the quantity of Nafion ionomer from 24 wt.% to 39 wt.% in catalyst layer. The effect of Nafion ionomer of each electrode was evaluated with cyclic voltammetry measurement. In addition, cell performance was obtained through single cell test using hydrogen and air. The Pt utilization and performance of single cell were changed by addition of Nafion ionomer to the electrode. Single cell fabricated with 33 wt.% of Nafion ionomer in catalyst layer showed the maximum Pt utilization and performance.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.49-59
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• 2010

Earthquake-induced liquefaction on saturated loose sand is well known in the world. Since Saemangeum Dike Project has a plan to be reclaimed with dredged sand on wide river, possibility of liquefaction should be checked. Section Dongjin5 was selected to evaluate possibility of liquefaction. Estimating method follows as 1) determination of PL value with SPT results, passing curve, and soil properties, 2) prediction for maximum earthquake acceleration, 3) calculation for FL value on depth with Korean specification for highway bridges, 4) visualization for possibility of liquefaction on all of project area with GIS 5) comparison with Japanese specification for highway bridges, Youd and Idriss method, and Andrus and Stokoe II method for verification, 6) ascertainment for the potential liquefaction with cyclic triaxial test. 7) establishing for countermeasure if needed. From the results, even though most of area covered with sand, no potential liquefaction exists except some areas. Those need to soil improvement with grout or attaching measurement on substructure.

• Journal of Ocean Engineering and Technology
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• v.21 no.3 s.76
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• pp.65-70
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• 2007

There are many kinds of protection methods for marine structures, with varyingeconomical and environmental advantages. The coating protection method is being widely used in both continental and marine structures. In this study, by adding some additives, such as Zn powder(Zn), carbon black(CB) to epoxy anti-corrosive paint, the effect on the corrosion resistance was investigated throughan electrochemical method. The additive of Zn(20)+CB(10) showed the lowest passivity current density. Polarization resistance in both cyclic voltammogram and impedance measurement of an additive of Zn(20)+CB(10) was also the largest value, compared to other additives. Furthermore, rusting and bubbling was not observed on the surface of the test specimen with the additive of Zn(20)+CB(10), compared to other specimens. It is suggested that the corrosion resistance of the anti-corrosive paint can be improved by using some additives.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.379-384
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• 2017

An electrochemical reduction of a mixture of NiO and rare earth oxides has been conducted to increase the reduction degree of rare earth oxides. Cyclic voltammetry (CV) measurement was carried out to determine the electrochemical reduction behavior of the mixed oxide in molten LiCl medium. Constant voltage electrolysis was performed with various supplied charges to understand the mechanism of electrochemical reduction of the mixed oxide as a working electrode. After completion of the electrochemical reduction, crystal structure of the reaction intermediates was characterized by using an X-ray diffraction method. The results clearly demonstrate that the rare earth oxide was converted to RE-Ni intermetallics via co-reduction with NiO.