• Corrosion Science and Technology
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• 제9권3호
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• pp.137-141
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• 2010

Sodium nitrite is widely used as one of the popular corrosion inhibitors for the protection of ferrous metal in closed cooling water system, such as a diesel engine and a chiller. The optimum treatment conditions are studied through laboratory tests using linear polarization resistance (LPR) technique. Corrosion rate of the carbon steel electrode could be maintained less than $2.5{\times}10^{-3}$ mmpy in the test condition of 500 ppm as ${NO_2}^-$, 200 ppm as $Cl^-$, $70^{\circ}C$ and pH 6.8. The pH control is confirmed not to be an important factor in the protection of carbon steel by sodium nitrite inhibitor. The addition of tolyltriazole was needed for the protection of the copper alloy in the sodium nitrite treatment system.

• 한국안전학회지
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• 제17권3호
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• pp.61-65
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• 2002

A study on the characteristics of electric shock in fresh water due to the leakage of submerged electric facility is conducted by using a reduced scale model at a scale of 1:10 in laboratory. Electric potential as a function of distance from leakage source, type of the leakage source, magnitude of the source voltage, submerged depth and diameter of a copper rod electrode is measured. On the basis of safety standard, separation for guarantee of safety is determined by the measured potential. Also supposing that body resistance is 500［$\Omega$］, the human reaction was estimated by calculating body current for some shock duration. Thus, in this paper, the hazard of the electric shock is assessed by introducing representative safety factors, body voltage and body current due to leakage source.

• 기술사
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• 제14권4호
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• pp.15-25
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• 1981

Electrical behaviors of the divalent silver oxide-zinc cell were analyzed for imporving capacity and keeping electrodes from passivation or sharp increases of cell internal resistance in the course of discharge. One of primary factors in relation to lowering performance can be depicted by cell internal resistance increase being created by various routes, first by insufficiency and/or the carbonation of the electrolyte, secondly by barrier blockage, thirdly by electrode passivation which are due to improper material use of wrong processing, and by gassing as fourth cause. The carbonation causes electrobyte to have impedance up as well as poor amalgamation, resulting in vigorous corrosion reaction of copper plated inner top, evolving hydrogen gas. Electrical characteristics of the cell was reviewed to elucidate relationships between the discharge capacity and the cell internal resistance.

• Tribology and Lubricants
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• 제29권2호
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• pp.77-84
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• 2013

A small engine-oil-deterioration detection sensor was developed and installed at the tip of a dipstick gage. The sensor part was manufactured using printed circuit board (PCB) manufacturing technology. A set of sensor covers was installed in order to protect the sensor and realize good signal stability. The small engine-oil-deterioration detection sensor system comprised a dual sensor having etched copper electrodes coated with gold and ceramic, a flexible PCB (FPCB) acting as electric wire, and a dummy PCB with only a lock connector. The sensor can easily be installed by insertion through the guide tube of a dipstick gage. Thus, a driver can easily handle it without further installation equipment. The sensor can determine the level of deterioration in the engine oil by estimating the corresponding dielectric constant of the engine oil.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1500-1502
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• 1998

Electro Discharge Machining (EDM) is a so-call nonconventional machining technique. This paper presents the experimental results of an EDM technique for the fabircation of microholes on #7440 pyrex glass substrates. With various applied voltages and various concentration of NaOH or KOH solution, the glass substrates have been microdrilled using the copper electrodes of which diameters are 250 ${\mu}m$ to 450 ${\mu}m$. The machined throughholes have been observed the top diameter, the bottom diameter and machining time have been measured. EDM in NaOH solution causes the fabrication to have better the surface condition, higher selective of electrode, lower concentration of solution with respect to EDM in KOH solution machined fabrication.

• Bulletin of the Korean Chemical Society
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• 제35권8호
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• pp.2519-2522
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• 2014

Recently, the observation of the electrocatalytic behavior of individual nanoparticles (NPs) by electrochemical amplification method has been reported. For example, the Iridium oxide ($IrO_x$) NP collision on the Pt UME was observed via electrocatalytic water oxidation. However, the bare Pt UME had poor reproducibility for the observation of NP collision signal and required an inconvenient surface pre-treatment for the usage. In this manuscript, we has been investigated other metal electrode such as Cu UME for the reproducible data analysis and convenient use. The $IrO_x$ NP collision was successively observed on the bare Cu UME and the reproducibility in collision frequency was improved comparing with previous case using the $NaBH_4$ pre-treated Pt UME. Also, the adhesion coefficient between NP and the Cu UME was studied for better understanding of the single NP collision system.

• 동력기계공학회지
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• 제5권4호
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• pp.61-66
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• 2001

Electro-Rheological(ER) fluids undergo a phase-change when subjected to an external electric field, and this phase-change typically manifests itself as a many-order-of magnitude change in the rheological behavior. This paper presents experimental results on material properties for an ER fluids of arabic gum components subjected to electrical fatigues. As a first step, ER fluids are made of arabic gum 25% of particle weight-concentration. Following the construction of test mechanism for estimated durability of ER fluid, the dynamic yield stress, shear stress and current density of the ER fluids are experimentally distilled as a function of DC electric field. The durability estimation of operated ER fluids are distilled and compared with those of unused ER fluids. In addition, the surface roughness of the employed electrode for copper and aluminum are evaluated as a function of the number of the electric-field cycles.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 춘계학술대회 논문집
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• pp.886-889
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• 2000

This paper describes the machining characteristics of the MoSi$_2$-based composites by electric discharge drilling with various tubular electrodes. MoSi$_2$-based composites has been developed in new materials for jet engine of supersonic-speed airplanes and gas turbine for high- temperature generator. By combining a nonconducting ceramics with more conducting ceramic it was possible to raise the electrical conductivity. In drilling by EDM, the dielectric flushed down the interior of the rotating tube electrode, in order to facilitate the removal of machining debris from the hole. Various metal-coated tubular electrodes of which core are copper and brass are used to know the effect of coating material on machinability of ED drilling.

• 한국해양공학회지
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• 제10권4호
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• pp.103-108
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• 1996

To syudy the change of prtential in the mortar-embedded precorroded rebar, a half cell method was adapted. The rebar was corroded by the salt spray and then the rebar embedded in the mortar. A saturated copper sulfate feference electrode was used. The corrosion potential of the rebar in the mortar specimen cured in air was increased, whereas that of the rebar cured in water was decreased with aging. The corrosion potential of the rebar in the mortar was decreased with corroded time by the salt spray. As the mortar thickness covered the rebar was increased, the corrosion potential of the rebar in the mortar was increased.

• 한국세라믹학회지
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• 제55권4호
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• pp.325-336
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• 2018

Perovskite solar cells (PSCs) are a new class of photovoltaic devices, which have attracted significant attention due to their remarkable optoelectrical properties, including high absorption coefficients, high carrier mobilities, long carrier diffusion lengths, tunable bandgaps, low cost, and facile fabrication. PSCs have reached efficiencies of 22.70% and 18.36% on rigid fluorine-doped tin oxide and poly(ethylene terephthalate) substrates, respectively; these are comparable to those of single-crystal silicon and copper-indium-gallium-selenium solar cells. Over the past eight years, the photo conversion efficiency of PSCs has been significantly improved by device-architecture adjustments, and absorber and electron/hole transport layer optimization. Each layer is important for the performance of PSCs; hence, we discuss achievements in flexible perovskite solar cells (FPSCs), covering electron/hole-transport materials, electrode materials. We give a comprehensive overview of FPSCs and put forward suggestions for their further development.