• 한국문화재보존과학회:학술대회논문집
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• 2005.11a
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• pp.231-241
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• 2005

• Journal of Conservation Science
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• v.20
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• pp.55-65
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• 2007

Black surface layers collected from stone pagodas were analyzed to study the effects of carbon compounds on the blackening of stone surface layer. The total amounts of carbon was measured through elemental analyser. Organic and elemental carbon were measured by combustion ihrornatographic $CO_2$ determination after elimination of carbonates carbon with acid treatment. The elemental carbon concentration in the black surface layer measured 0.52wt.%. This value is not sufficient to explain the complete blackening of stone surface. To trace the origin of carbon in black surface layer on the stone pagoda, aerosol samples for PM 10 were collected at the near sites of the pagoda. The major components of them were soluble ions(42.8wt.%), carbon(38.4 wt.%) and crustal matter(16wt.%). From the high content(13wt.%) of elemental carbon in aerosol ran be deduced that it may be a prime origin for the elemental carbon in the black surface layer on the stone pagoda. The crustal matter in aerosol can be also a origin of silicate mineral in black surface layer and plays a important role in the darkening of black surface layer.

• Journal of Conservation Science
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• v.29 no.4
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• pp.407-420
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• 2013

The stone sculptures in Gyeongbokgung Royal Palace are mainly composed of granite (884 sculptures, 96.7%) and marble (25 sculptures, 2.7%) that originated in several different quarries. Main deterioration forms are crack (24%), break-out (21%), exfoliation (36%), granular disintegration (9%) and blackening (20%). Crack and break-out are dominant contributors to high physical deterioration degree, and blackening is major weathering form of intensive discoloration. The Gyeonghoeru, Geunjeongjeon and Pumgyeseok areas require urgent and high conservation maintenance with short-term periodic monitoring since proportions of 3-grade deterioration were calculated higher than others as 55% for Gyeonghoeru, 29% for Geunjeongjeon, 11% for Pumgyeseok area. The Pumgyeseok (officials' rank stone), especially, needs intervention for protective facility due to its material vulnerability to weathering in outdoor environment.

• Horticultural Science & Technology
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• v.33 no.1
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• pp.55-60
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• 2015

Skin blackening is a serious postharvest disorder occurring in 'Fuyu' persimmon fruits (Diospyros kaki, 'Fuyu'). Phenolic content, polyphenol oxidase (PPO) and peroxidase (POD) activity, and lipid saturation were investigated in skin tissue of 'Fuyu' fruits. The phenolic compounds were accumulated unevenly on fruit skin depending on sunlight exposure, i.e., the most accumulation on sunny side and the least on the opposite, shaded side. The fruits harvested from shaded branches inside the canopy showed relatively even distribution of phenolic compounds in the skin. The activity distribution of PPO and POD were also uneven but only in fruits suffering f rom skin b lackening disorder, w ith the h ighest and the lowest a ctivity of PPO and P OD, respectively, in the blackened area of the fruit. When the sunny, southern sides of fruits were marked at harvesting time and fruits were stored at low temperature, a round black spot, as a symptom of skin blackening disorder, developed during storage exactly on the marked region. In addition, the sunny side of fruit showed higher lipid saturation, thus indicating adaptation to high temperature caused by the sunlight. These results suggest that the skin blackening disorder of 'Fuyu' fruits can be considered as a kind of chilling injury symptom that develops on the high-temperature-acclimated skin tissue of sunlight-exposed fruits when they are later exposed to low temperature.

• 한국문화재보존과학회:학술대회논문집
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• 2007.10a
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• pp.65-66
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• 2007

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.367-370
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• 2007

An EEFL with the sodium free alumino-silicate glass of high K and low $tan{\delta}$, has been investigated. As compared with borosilicate and the soda-lime EEFLs, the luminous efficiency as well as the pinhole stability of new EEFLs improves remarkably without blackening of $NaHg_2$.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.33 no.2
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• pp.49-57
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• 2001

This study was performed to identify the effect of calendering variables on the properties of coated paper such as sheet gloss, surface roughness, opacity, etc. The effect of calendering variables including the number of nips, pressure, machine speed and moisture content on the properties of coated paper was investigated. The calender was installed with two steel rolls and one cotton-made roll. With this calender, the coated sheets were passed through the calender from 1 to 4 times, applying the linear pressure on calender rolls, 5 through 100kg/cm and operating the machine speed 3 to 12m/min. Also, the moisture content of coated sheet was varied about 5 and 10%. It was found that sheet gloss and surface roughness of coated paper was increased with increasing the number of passing nips, linear roll pressure and the moisture content of coated paper. But it was shown that the opacity and brightness of coated paper were decreased under the above conditions due to the blackening. It was also suggested that the soft nip possibly increased the thermoplasticity of coating layer with the heat of steel roll, resulting in the reinforcement of surface properties positively. The sheet gloss and surface roughness of coated paper could be improved by the longer dwell time over the rolls.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.219-219
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• 2009

ceramic metal halide lamps are a subset of high intensity discharge lamps so named because of their high radiance These lamps weak ionized plasma in a fire-resisting but light transmissive wrapping by the corridor of current through atomic and molecular vapors. for commercial applications, For commercial applications, the conversion of electric power to light must occur with good efficiency and with sufficient spectral content throughout the visible (380-800 nm) to permit the light so generated to render colors comparable to natural sunlight. the purpose of this paper is to carry out a study on the variation of ageing time(2000 On/Off[hr]) on the performance of 150W CMH lamps. Experimental results show that the blackening by reacting W(tungsten)with I atomic has been created in the arc tube of an ageing lamp(2000 On/Off[hr]), the arc was unstable, and increased a lamp resistance made lamp voltage increases significantly. Also, Color temperature of the ageing lamp was moved by the losses of Ho with Dy atomics and by recombination of Na with I.

• Korean Journal of Metals and Materials
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• v.50 no.5
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• pp.353-360
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• 2012

The corrosion product of archaeological iron objects is supposed to be removed because it causes re-corrosion. So far it is removed by scapel and sand blaster but they depend on the skill and experience of a conservator and the glass-dust of the sand blaster is harmful to humans. Therefore this study applies a laser cleaning system which is used in various industrial cleaning processes, to remove corrosion product from archaeological iron objects. In addition, this work studies the alternation of corrosion product after laser irradiation, which evaluates the reliability of the laser cleaning system. Optical microscopy, SEM-EDS, XRD, Raman have been used to observe and analyse the surface of the objects. The results show the capacity of laser cleaning some corrosion product, but blackening appears with increasing pulses and laser energy, and some corrosion products, goethite and hematite, are partially altered to magnetite. These problems, blackening and alternation of corrosion product, should be solved by further studies which find the optimal laser irradiation condition and use a wetting agent.

• Journal of the Mineralogical Society of Korea
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• v.17 no.1
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• pp.75-83
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• 2004

Blackening on stone monuments is serious problem, because it is not only aesthetically unattractive, but also an important process in stone deterioration. Black surface layers contain often a large amounts of iron compound. Therefore it is assumed that besides another elements the iron have influence on blackening of surface. After the samples of black surface layers were collected from the stone monuments (Museumsinsel) in Berlin, Germany, especially in this study has been used Mossbauer spectroscopy in order to determine the valence and chemical composition of iron. Mineralogical and chemical analyses were carried out X-ray diffractormetry and X-ray fluorescence method on the black surface layer's samples and original stone samples. The origin of Iron compound in the black surface provides the important clue for the conservation work of stone monuments, like removing of black surface. To find it, black surface layer on white sandstone -it contains very small amount of iron compound- was compared with that on the red sandstone (Fe contains very small amount of iron compound- was compared with that on the red sandstone (Fe abundant). As a results, it is assumed that the iron in black layer on white sandstone is originated mainly from a surrounding environmental material and for the iron in black layer on the red sandstone is responsible the original stone. Even if black surface layer was removed from the red sandstone, some other conservation method should be studied beyond removing of black surface layer, because the iron can move continuously from the inner zone of original stone to surface area.