• Journal of Pharmaceutical Investigation
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• v.35 no.6
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• pp.467-469
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• 2005

The purpose of this study was to investigate main ingredients of Hwangtoh (Korean yellow ochre), especially ferric oxide $(Fe_{2}O_{3})$ content. In this study, X-ray fluorescence spectrophotometry was employed to analyze the ingredients of Hwangtoh. The ferric oxide $(Fe_{2}O_{3})$ contents of Hwangtoh from Hwa Sun, Ham An, Chil Gok, Sun Chun, Ha Dong, San Chung, Go Chang, Kim Che and Jeong Eup were 1.5, 5.66, 11.76, 6.63, 2.74, 11.4, 4.84, 7.21 and 6.23%, respectively. Based on the above results, any Hwangtoh sample didn't meet the ferric oxide $(Fe_{2}O_{3})$ content criterion.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.3
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• pp.65-71
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• 2018

There is no significant difference in the initial viscosity of a propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material with added yellow iron oxide is faster than that with the addition of red iron oxide. Specifically, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure with yellow iron oxide than with red iron oxide. The initial viscosity was lowest at 71% of the large particle to small particle ratio.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.390-393
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• 2010

The thermal decomposition rate of ammonium perchlorate with 3% of yellow iron oxide, FeOOH was found to be much faster than with red iron oxide, $Fe_2O_3$. By applying yellow and red iron oxide as a burning rate modifier to HTPB/AP propellant, burning rate of the HTPB/AP propellant with yellow iron oxide was shown to be 10 ~ 25% faster than with red iron oxide. There was no special difference in viscosity and hardness buildup of yellow and red oxide added HTPB/AP formulations.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.498-503
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• 2017

There is no unusual difference in the initial viscosity of the propellant applied with yellow iron oxide and red iron oxide. In addition, the thermal decomposition rate of the material added with yellow iron oxide is faster than that of the addition of red iron oxide. Especially, it was confirmed that the pressure exponent was 18% lower at high temperature and high pressure. The initial viscosity was lowest at 71% of large particle/small particle ratio

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.12-17
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• 2020

The mechanical properties of the propellant with yellow iron oxide were slightly increased compared to the propellant with red iron oxide. The propellant with yellow iron oxide used two types of AP. As the ratio of small particles of AP increased, the burning rate increased. The propellant may be applied to the propellant under operating conditions of 17.5 mm/sec or less having a pressure index of 0.5. The burning rate downs in the mixer scale-up. The stress at maximum load of propellant decreased and the strain at maximum load increased in the mixer scale-up. The yellow iron oxide did not affect the adhesive force between the insulation/liner/propellant.

• Journal of Pharmaceutical Investigation
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• v.30 no.3
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• pp.219-222
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• 2000

The purpose of this research was to investigate the general properties and main ingridients of Hwangtoh, which is the Korean loess. It is well known as a raw material of pottery shown to be widely scattered on the earth, especially in Korea. It belongs to primary clay that was found to be rich on mountain surface or field. In this study, XRF Spectral method was employed to analyze the chief ingredients of Hwangtoh, being found to consist of $43{\sim}50%\;SiO_2,\;2{\sim}34%\;Al_2O_3,\;2{\sim}3%\;Mg,\;2{\sim}3%\;Na\;and\;1{\sim}2%\;K$. The ferric oxide contents of Hwangtoh from San Chung, Ha Dong, Ko Ryung, Ouk Chong, Bang Gae and Song Kwang were 6.46, 7.96, 11.26, 9.36, 9.06 and 9.28 %, respectively. The general characteristics of Hwangtoh from different places were studied by determining the content of water and the capacity to maintain temperature. Based on the above results, Hwangtoh could be said to have better quality than primary clay of Kaolin dose, and also would be able to find an application in construction formulations.

• Journal of the Korean Chemical Society
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• v.19 no.2
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• pp.142-146
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• 1975

The formation of iron oxide hydroxide in a ferrous sulfate was studied in different contents of iron in the solution at a temperature range of 90 to $100^{\circ}C$ under 1${\sim}$3 atmospheres. The Mohr's salt thus formed was hydrolyzed under 1 to 3 atmospheres, in 14 to 72 g/l of iron content in the solution pH 3 or 6 for two hours at 90 to $100^{\circ}C$. The results obtained was as follows; 1) In Mohr's salt solution, as the iron content was increased, with decreasing the concentration of hydrogen ion, the yield of iron oxide hydroxide was gradually increased. 2) When iron content in Mohr's salt solution was 42.81 g/l, 91.5% of iron was recovered in the form of $\alpha$-goethite similar to yellow grade of natural goethite. 3) When $\alpha$-goethite obtained was calcined of $500^{\circ}C$, it was turned into ${\alpha}$-ferric oxide with a redish brown colour.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.6
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• pp.10-15
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• 2020

This study is about the changes in mechanical and combustion properties after the production of the combustion catalysts FeOOH and Fe₂O₃ having the same manufacturing method and application to the solid propellant. In order to make the FeOOH and Fe₂O₃ having the same manufacturing method, FeOOH was calcined at 200, 300, 400, 500℃ for 2 h, and the XRD results were confirmed. In addition, after applying the prepared catalyst to a solid propellant, it exhibited change in mechanical and combustion properties. As result of XRD, FeOOH was confirmed to change the crystal phase from Geothtie to Hematite between 200 and 300℃. The stress of the propellant hardly changed as the calcination temperature of the combustion catalyst incredsed, but the elongation increased when catalyst was calcined. the maximum value at 300℃. The burning rate confirmed that FeOOH without calcination was about 3~5% faster than other catalysts.