• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.803-805
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• 2008

For the life estimation of CCFLs in edge-lit LCD modules has been required CCFL blackening test, which is executed in the state of low current and long-time operation under the high temperature condition. We investigated the reason why CCFL blackening happened more easily in the above test conditions and the way how mechanical parts had influence upon CCFL blackening in the edge-lit LCD modules.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2262-2267
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• 2010

In order to analyze the reason of wall blackening, which affect the decline of lifetime in a ceramic metal halide lamp, we carried out the deterioration of ceramic tubes by a change in operating conditions with arc tubes of two types of spherical and cylindrical, and we have confirmed the cause of wall blackening through the analysis of element composition and spectrum from SEM/EDS and spectrum analyzer. Wall blackening of tungsten was shown by sputtering from ignition in 20 minute on/off condition and wall blackening from chemical reaction between PCA wall and rare earth halides was shown significantly in a condition without on/off test. Especially, the wall blackening and the decline of luminous flux were reduced by inner convection in spherical type arc tube. Moreover, the color temperature and color coordinate were changed by reduction of emission spectrum of Dy which causes the chemical reaction with PCA wall.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1994.11a
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• pp.101-105
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• 1994

A/F sensor with a sensing and a pumping element, which is made of YSZ(yttria stabilized zirconia) sheets, can be used for the combustion control of lean burn engine. A/F sensor can detect the oxygen partial pressure in more wide range than the other oxygen sensors, such as the limiting current type oxygen sensor and λ-sensor. However this sensor has the disadvantage that the characteristics has been degraded rapidly due to the physical or electrochemical reasons. The blackening phenomenon is known as one of the degradations caused by high voltage biased for oxygen pumping. In this paper, we have studied to analyze the blackening phenomenon by comparing two characteristics between before and after blackening in impedance spectroscopy, and discussed the blackening mechanism.

• Journal of the Korean Vacuum Society
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• v.17 no.6
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• pp.481-486
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• 2008

The different degrees of blackening were observed at the inner surface of borosilicate, soda-lime, and aluminosilicate glass tubes having different sodium (Na) contents. The sodium contents ($Na_2O$) within the borosilicate, soda-lime, and aluminosilicate glass tubes were found to be 4%, 14%, and 0.06%, respectively. The degree of blackening was shown to increase as the sodium content within the glass of the fluorescent lamp containing Ne+Ar+Hg gas mixture. Higher degree of blackening was observed from the inner surface of the glass tube coated with $Y_2O_3$. The blackening was found to be originated from the amalgam of $NaHg_2$ generated by the chemical reaction between the mercury ions within the discharge gas and sodium within the glass tube during operation.

• Journal of the Korean institute of surface engineering
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• v.56 no.1
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• pp.69-76
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• 2023

The effects of hairline treatment on surface blackening and thermal diffusion behaviors of Zn-Al-Mg alloy coated steel sheet were evaluated by the three-dimensional surface profiler and laser-flash technique. The metallographic observation of coating damages by hairline treatments showed that several cracks were initiated and propagated along the interface between primary Zn/eutectic phases. As the hairline processing became more severe, the crack occurrence frequency in eutectic phase of coating layer and the surface roughness increased, which had a proportional relationship with the level of blackening on the coating surface. In addition, the higher interfacial areas of the blackened coating surface, caused by the hairline process, led to an increase in thermal diffusivity and conductivity of the coated steel sheet. On the other hand, when the coating damage by hairline treatment was excessive and the steel substrate was exposed, there was little difference between the thermal diffusivity/conductivity of the untreated sample though the blackening degree was higher than that of untreated sample. This work suggests that the increase in the surface areas of the coating layer without exposure to steel substrate through hairline treatment can be one of the effective technical strategies for the development of Zn-Al-Mg alloy coated steel sheets with higher blackening level and thermal diffusivity.

• Korean Journal of Organic Agriculture
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• v.23 no.1
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• pp.91-101
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• 2015

'Chuhwangbae' pears (Pyrus pyrifolia Nakai) were investigated on how types of paper bag and harvesting dates influenced on skin blackening before harvest as well as fruit quality after harvest. Experiments included four different types of paper bags (NP/YP, GP/YP, NP/BP, and NP/RP) and five different harvesting dates [160, 170, 180, 190, and 200 days after full bloom (DAFB)]. NP/YP and GP/YP indicated for newspaper- and gray paper-outer bag, respectively, with yellow paper-inner bag of the both. NP/BP and NP/RP indicated for newspaper-outer bag of the both with black paper- and red paper-inner bag, respectively. The NP/YP (newspaper/yellow paper) showed high absorbance and air and water vapor permeability in the bags, while the NP/RP (newspaper/red paper) resulted in poor physical properties in the bags. Fruit enclosed with NP/YP resulted in the absence of skin blackening, but fruit with NP/RP bags had the highest skin blackening (12.7%). Occurrence of skin blackening was concentrated on the middle and calyx end-part of fruit region. NP/RP bag treatment was likely to increase fruit weight, firmness, titratable acidity, and fruit surface color. Harvest at high relative humidity in air increased skin blackening of fruit. Later fruit harvest, such as 190 and 200 DAFB, increased skin blackening, fruit weight, and sugar content while decreasing fruit firmness and titratable acidity.

• Korean Journal of Food Science and Technology
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• v.28 no.5
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• pp.910-915
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• 1996

Ascidian muscle was blackened during the frozen storage, so the prevention against blackening was investigated. Low storage temperature and packaging in polyethylene bags delayed the blackening of ascidian muscle during the frozen storage. The blackening was prevented by dipping for $3{\sim}5$ minutes in 3% brine solution containing 0.3% citric acid, packaging in the polyethylene bag, freezing at $-45^{\circ}C$ for 5 hours and storing at $-20^{\circ}C$. Under this condition, the color and the quality of frozen ascidian muscle were nearly not changed for 200 days.

• Clean Technology
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• v.27 no.1
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• pp.17-23
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• 2021

Black polymer spacers are currently used for physically separating aligned camera lenses in camera modules of mobile phones. However, the mechanical properties of polymer spacers have their limits, especially in the current trend of using more lenses in thinner camera modules. Thus, copper (Cu) becomes a good candidate for those polymer spacers because of its superior mechanical properties and its inherent blackness due to its black surfaced oxides, such as copper (II) oxide (cupric oxide, CuO). The latter property is critical in quality control because the closer the color of a spacer is to black, the less light interference and flaring phenomena can occur. A standard Cu blackening process and its operational conditions were proposed in this study through a comprehensive analysis of previous research and patents. The Cu blackening process is composed of cleaning, deoxidizing, activating, blackening and sealing. The effects of operational parameters, such as the temperature of each unit process and the activator concentration, were then investigated by measuring the blackness of the Cu strips with a colorimeter. The proposed operational conditions were determined by whether the blackness of Cu strips was within the on-spec. value used in the field.

• Bulletin of the Korean Chemical Society
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• v.23 no.3
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• pp.369-373
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• 2002

The liquid phase oxidation of p-xylene has been carried out with oxygen-enriched gas, and the manganese component was precipitated probably via over-oxidation to $Mn^{4+}$. The precipitation increased with rising oxygen concentration in the reaction gas and occurred mainly in the later part of the oxidation. The activity of the reaction decreased, and the blackening of the product and side reactions to carbon dioxide increased with the degree of precipitation. Precipitation can be decreased with the addition of metal ions, such as cerium, chromium and iron.

• Journal of Electrical Engineering and Technology
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• v.6 no.1
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• pp.123-127
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• 2011

To clarify the relations of optical properties to the main factors responsible for the loss and damage of luminous efficacy, a 20 min turn-on/turn-off test for 2,000 h for a ceramic metal halide lamp is conducted. The corrosion rates of the arc tube wall and electrode are estimated based on thermal stress. Wall blackening is attributed to the tungsten being transported from the hot electrode tips to the relatively cold arc tube wall. Furthermore, the grain boundaries of the arc tube are changed by the degradation. Distortion of the electrode is observed, and the ignition and the driving voltage of the load both increase. Finally, the color rendering index and the color coordinates are changed after the degradation. The luminous flux and the intensity of the luminous distribution are decreased significantly.