• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.6
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• pp.290-297
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• 2004

The color enhancement of natural ruby produced from Mong Hsu were carried out by the heat treatment using gas diffusion. The natural ruby in this paper has a colored patch of which the color ranges from blue to a color close to black. The most favorable heat treatment conditions were as follows; range of temperature $1400~1600^{\circ}C$, duration 12 hrs, $O_2$ atmosphere. The color tone of ruby obtained under the optimum conditions was overall clear red by partial removal of colored patch. From EPMA results, part of blue or black colored patch within ruby were found to occur by charge transfer between $Fe^{2+}{\;}and{\;}Ti^{4+}$ . These results are consistent with the XRF that contents of $Fe(Fe^{2+}{\;}or{\;}Fe^{3+}$) and $Ti^{4+}$ ion to cause a blue or black colored patch after heat treatment became slightly less than with non-treated ruby. The silk formed on the surface of ruby heat treated for 12 hrs at $1700^{\circ}C$ were found to be generated by re-crystallization of rutile $TiO_2$ by XPS analysis.

• Korean Journal of Materials Research
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• v.15 no.4
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• pp.252-256
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• 2005

We removed the bluish of the natural ruby successfully by vacuum annealing, and measured the color evolution with annealing time and temperature. We varied the anneal temperature and time $800\~1500^{\circ}C$ and $3\~26$ hrs, respectively. The color evolution of rubies with annealing condition was recorded by a digital camera and a color coordination visible spectrometer. We determined the optimum bluish eliminating annealing condition was $1500^{\circ}C-3hr$, which conserving the natural inclusions. We suggest the bluish shrink with diffusion coefficient of $D=(5\times10^{-3}){\exp}(-200.000/RT)[cm^2/s]$. We propose the color of ruby may be determined as the identical red color if the color difference between two samples are less than 1.0, and the color difference nay be an auxiliary standard to evaluate the color of rubies.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.4
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• pp.165-171
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• 2009

In this study, ruby single crystals were successfully grown by flux method using an alumina crucible. The alumina crucible can be a substitute for the platinum crucible of high price. The ruby single crystals were grown in the temperature range of $915{\sim}1350^{\circ}C$ for 240 h, using $PbO-B_2O_3$ mixture. The grown ruby crystals with 9.02 ${\times}$ 6.36 mm in size exhibited red color and were transparent. The optical and structural properties were examined by UV-VIS spectrometry, FTIR and XRD. The optical properties of theses crystals were similar to those of the natural ruby and synthetic ruby grown by other methods.

• Economic and Environmental Geology
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• v.47 no.6
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• pp.563-569
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• 2014

Ruby is one of the most favor colored gem, for beautiful red tone, be high in scarcity value. However, rubies with high quality are produced in restricted regions, such as in Thailand, Sri Lanka, Myanmar, and Tanzania etc., and they have been gradually exhausted by mining for a long period. Therefore, improving qualities of low level rubies with various treatments is arising an alternative way to obtain better rubies. Gemological and mineralogical properties of the natural ruby from Tanzanian were studied with heat treatments. Those characteristics were compared between only heat and adding flux materials under heating. Tanzanian raw rubies were applied a heat treatment ($1,600^{\circ}C$ for 6 hours). However, chromameter and UV-Vis analyses found that a simple heat treatment is inappropriated for the Tanzanian ruby. Although $Cr^{3+}$ containing for red color in the ruby increased with heat treatment, the ruby displays dark medium red because of Fe in the ruby as a form of $Fe_2O_3$. The low transparency after heat treatment is attributed to the recrystallization of $SiO_2$ which has a low melting point. Chromameter confirmed adding Pb-containing flux under heating greatly improves the clarity and color of Tanzanian rubies with micro-fractures and cavities on the surface. EMPA results show that Pb as an additive fills the cavities and cracks on raw Tanzanian rubies during the heat treatment. As a rewult of it, the quality of the Tanzanian ruby raw dramatically improved. These results indicate that the heat treatment with an additive (Pb in this study) is an effective way to obtain better quality of the Tanzanian ruby. Consequently, this study suggests a suitable method to improve the properties of the Tanzanina ruby. The result of this study would provide useful information to upgrade the qualities of similar gem stones such as corundum and sapphire.

• Korean journal of applied entomology
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• v.18 no.2 s.39
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• pp.107-110
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• 1979

An parasite, Anicetus beneficus was introduced from Japan to Jeju-do, Korea in 1975, and evaluated as a biological agent for control of the ruby scale, Ceroplastes rubens MASKELL. The results were as follows: 1. A major pest of citrus, ruby scale had one generation a year and hatched from late June to early August with the peak hatching in the middle of July. 2. A. beneficus was widely distributed in 16 citrus growing areas since released in 1975. 3. The pnupulation of ruby scales was considerably decreased by increasing of the parasites. Mean percent parasitism of A. beneficus was 1.7 in 1975, 14.1 in 1976, 31.0 in 1977 and 37.0 in 1978.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.11 no.6
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• pp.104-111
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• 2008

Plant growth and variegated leaf color changes of three leaf variegated Sedum spectabile varieties 'Variegatum', 'Frosty Morn', red colored 'Washfield Ruby', and one Sedum lineare variety 'Variegatum' and Sedum sarmentosum under three levels of shading conditions were examined for leaf ornamental value improvement. Shading levels were 40%($1,500{\mu}mol{\cdot}m-^2{\cdot}s-^1$), 70%($750{\mu}mol{\cdot}m-^2{\cdot}s-^1$) and 85%($375{\mu}mol{\cdot}m-^2{\cdot}s-^1$). Improvements of leaf ornamental value of 'Variegatum' 'Frosty Morn' and 'Washfield Ruby' were observed at 40% shading level and plant heights and leaf sizes were also increased. Plant height of S.sarmentosum were shorten under direct sun light condition and leaf color changed to greenish yellow(RHS143B) but deep green color(RHS144A) was observed under shading conditions. Endurance of S.sarmentosum was stronger than other species and leaf ornamental values remained well at 70% shading level. Leaf width of S.lineare 'Variegatum' were not changed under shading conditions but leaf length was increased. Leaf color was Deep green color was greenish yellow under direct sun light but deepest green color was observed at 85% shading level. Consider all ornamental value criteria, best shading conditions for S.lineare 'Variegatum' were ranged 40% to 70%.

• Journal of the Mineralogical Society of Korea
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• v.29 no.4
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• pp.191-198
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• 2016

Pyromorphite($Pb_{4.85}(P_{1.02}O_4)_3Cl_{1.04}$) which belongs to the apatite group was compressed up to 33.4 GPa for its equation of state at ambient temperature. High pressure experiment was performed with symmetrical diamond anvil cell employing the angle dispersive X-ray diffraction method. Pressure was determined by ruby fluorescence calibration method. No phase transition were observed and bulk modulus was determined to be 80(7) GPa when $K{_0}^{\prime}=13(2)$. Employing the normalized pressure-normalized strain analysis, reliability check of the compressible behavior was conducted.

• Journal of the Mineralogical Society of Korea
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• v.31 no.4
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• pp.277-285
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• 2018

Azurite ($Cu_3(CO_3)_2(OH)_2$) was compressed up to 21.52 GPa for its behaviors at ambient temperature. High pressure experiment was performed using the symmetrical diamond anvil cell employed in the angle dispersive X-ray diffraction method. Pressure was determined by ruby fluorescence calibration method. No phase transitions were observed within the present pressure limit and bulk modulus was determined to be 54.4 GPa when ${K_0}^{\prime}$ is fixed to be 4. Applying the normalized pressure-strain analysis, reliability of the azurite compression pattern was checked.

• Nuclear Engineering and Technology
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• v.54 no.5
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• pp.1652-1656
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• 2022

Fire tests were conducted on cables using fire-retardant paint employed in nuclear power plants that transmit electrical power, control and instrument signals. The failure criteria of various power and control cables coated with fire retardant coating at three different coating thicknesses (~0.5 mm, 1.0 mm & 1.5 mm) were studied under direct flame test using Container Fire Test Facility (CFTF) based on standard tests for bare cables. A direct flame fire test was conducted for 10 min with an LPG ribbon burner rated at ten by fixing the cable samples in a vertical cable track. Inner sheath temperature was measured until ambient conditions were achieved by natural convection. The cables are visually evaluated for damage and the mass loss percentage. Cable functionality is ascertained by checking for electrical continuity for each sample. The thickness of cable coating on fire exposure is also studied by comparing the transient variation of inner sheath temperature along the Cable length. This study also evaluated the adequacy of fire-retardant coating on cables used for safety-critical equipment in nuclear power plants.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.15 no.4
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• pp.145-151
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• 2005

Color enhancement of African rubies with dark red was carried out by the heat treatment and the hydrothermal treatment method respectively. The heat treatment method brought about an adverse effect causing the color to be deteriorated. However, the hydrothermal treatment method enhanced its color and clarity. The hydrothermal treatment conditions for color enhancement of them were as follows: solvent: 0.9M $Na_2CO_3-1M\;K_2CO_3$, temperature: $450^{\circ}C$, duration: 48 hrs, filling: $30\%$, pressure: 375 atm. As the results of characteristics for African rubies obtained under these conditions, it was known that the amount of $Cr^{3+},\;Fe^{3+},\;Ti^{4+}$ was reduced after the hydrothermal treatment from the ICP/MS and XRF analyses. Also, it was found that the red color from the colorimeter analyses was getting lighter. These results were consistent with the PL analysis showing that the intensity of the luminescence peak generated by the electron transition of $Cr^{3+}$ ion became lower after the hydrothermal treatment compared with the non-treated rubies.