• Journal of the Korean Ceramic Society
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• v.28 no.12
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• pp.996-1004
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• 1991

In this study, we tried to synthesis iron hydroxide suitable for longitudinal magnetic recording media from waste acid, which is a by-product of an iron works factory. Effects of initial pH of reactants, reaction temperature, reaction time for the synthesis of acicular iron hydroxide were studied in relation to particle properties of iron hydroxide and magnetic properties of maghemite powders. As the pH in reactant solution increased, $\beta$-FeOOH(pH=4.5), mixture of $\beta$-FeOOH and $\alpha$-FeOOH(4.5$\alpha$-FeOOH and Fe3O4(6.4$\alpha$-FeOOH (pH>13) was found to from in order. Especially, $\alpha$-FeOOH formed above pH 13 was single phase with superior acicularity. The temperature range over which the single-phase goethite can be formed increased as the initial pH of reactants increased (pH 13:10~5$0^{\circ}C$, pH 13.2:10~7$0^{\circ}C$, pH 13.5:0~8$0^{\circ}C$). The goethite formed between 40~6$0^{\circ}C$ has superior characteristics because the acicularity increased with increasing temperature but at high temperature (>6$0^{\circ}C$) Fe3O4 (pH=13) was found to start to form. Generally, single phase of goethite was found to form after one hour when an optimized condition. The particle size of goethite did not change as the reaction time increased over one hour. Accordingly, the magnetic properties of ${\gamma}$-Fe2O3 produced from goethite were not altered.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.321-327
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• 2024

Out-of-home (Out-of-Home) advertising can be an effective means of delivering messages for preventing drowsy driving, given that it is exposed at locations and times where vehicle traffic occurs. This study investigated the influence of message framing of drowsy driving prevention OOH advertising and regulatory focus on the intention to drowsy driving prevention behaviors by an experimental study targeting 200 university students. The results showed an interaction effect between message framing and regulatory focus on the intention to drowsy driving prevention behaviors. While no significant differences were observed in the intention to drowsy driving prevention behaviors based on regulatory focus for positively framed messages, for negatively framed messages, a higher intention was observed when the prevention focus group rather than promotion focus group. This study focuses on two key areas: how messages are crafted (message framing) and the characteristics of the people who receive them (regulatory focus). By exploring these aspects, it provides valuable theoretical and practical knowledge. Essentially, it opens doors for creating message strategies that are finely tailored to suit the preferences of the audience. This advancement is vital for researchers and practitioners as it enhances the effectiveness of communication efforts.

• Proceedings of the Korean Ceranic Society Conference
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• 2003.04a
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• pp.33.2-33
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• 2003

• Proceedings of the Materials Research Society of Korea Conference
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• 2005.05a
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• pp.81-81
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• 2005

• Korean Journal of Materials Research
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• v.15 no.5
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• pp.348-352
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• 2005

Gallium oxyhydroxide (GaOOH) powders were heat-treated in a flowing ammonia gas to form GaN, and the reaction kinetics of the oxide to nitride was quantitatively determined by X-ray diffraction analysis. GaOOH turned into intermediate mixed phases of $\alpha-\;and\;\beta-Ga_2O_3$, and then single phase of GaN. The reaction time for full conversion $(t_c)$ decreased as the temperature increased. There were two-types of rapid reaction processes with the reaction temperature in the initial stage of nitridation at below $t_c$, and a relatively slow processes followed over $t_c$ does not depends on temperatures. The nitridation process was found to be limited by the rate of an interfacial reaction with the reaction order n value of 1 at $800^{\circ}C$ and by the diffusion-limited reaction with the n of 2 at above $1000^{\circ}C$, respectively, at below $t_c$. The activation energy for the reaction was calculated to be 1.84 eV in the temperature of below $830^{\circ}C$, and decreased to 0.38 eV above $830^{\circ}C$. From the comparative analysis of data, it strongly suggest the rate-controlling step changed from chemical reaction to mass transport above $830^{\circ}C$.

• Journal of Environmental Health Sciences
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• v.21 no.4
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• pp.24-31
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• 1995

Gas sensing element, $\alpha-Fe_2O_3$ was synthesized by dehydration, reduction, and oxidation of $\alpha-FeOOH$, which was synthesized with $FeSO_4\cdot 7H_2O$ and NaOH. They were produced as a bulk-type, a thick film-type. Then, their responses and mechanisms of response to the gas of carbon monoxide were studied. The qualities of gas sefising elements are decided by the structure and the relative surface area. In the process of $\alpha-FeOOH$ synthesis, the effects of reaction conditions as the equivalent ratio, on the structure and the relative surface area of gas sensing element were observed. The changes of the structure were measured with XRD, SEM,TG-DTA and BET. The resistance changes of the synthesized gas sensor in the air were measured. The response ratio were also measured for the changes of working temperature and gas concentration. As a result of analysis with XRD, it was confirmed that the the best conditions for the synthesis of $\alpha-FeOOH$ were equivalent ratio 0.65. The thick film-type element of $\gamma-Fe_2O_3$ responded more quickly than the bulk-type did. The structure and the relative surface area of the $\rho-FeOOH$ were confirmed as the important factors deciding gas response charcteristics.

• Journal of the Korean Society of Safety
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• v.11 no.2
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• pp.67-78
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• 1996

Gas sensing element, $\gamma-Fe_2O_3$was synthesized by dehydration, reduction, and oxidation of $$${\gamma}$-FeOOH, which was synthesized with $FeSO_4\;{\cdot}\;7H_2O$ and NaOH. They were produced as a bulk-type, a thick film-type. Then, their responses and mechanisms of response to the gas of liquefied-petroleum were studied. The qualities of gas sensing elements are decided by the structure and the relative surface area. In the process of $\alpha-FeOOH $synthesis, the effects of reaction conditions as the equivalent ratio, on the structure and the relative surface area of gas sensing element were observed. The changes of the structure were measured with XRD, SEM, TG-DTA and BET. The resistance changes of the synthesized gas sensor in the air were measured. The response ratio were also measured for the changes of working temperature and gas concentration. As a result of analysis with XRD, it was confirmed that the the best conditions for the synthesis of $\alpha -FeOOH$ were equivalent ratio 0.65. The thick film-type element of $\gamma-Fe_2O_3$responded more quickly than the bulk-type did. The structure and the relative surface area of the $\alpha-FeOOH $were confirmed as the important factors deciding gas response charcteristics.

• 보존과학연구
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• s.16
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• pp.59-111
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• 1995

Chemical composion and crystal form of Corrosion products found on archaeological iron objects were analyzed using X-ray fluorescence analysis, micro-X-ray powder diffraction analysis and ion chromatographic technique. The nature and behavior of the corrosion products were studied in order to aid in the conservation and restoration of burial iron objects. Twenty-two samples analyzed in this study were collected from iron object found in Korea and Japan. The corrosion products of iron objects from burial mounds contain $\alpha$-FeOOH, $\beta$-FeOOH, $\gamma$-FeOOH, $Fe_3O_4$and amorphous iron hydroxides. The content of $\alpha$-HeOOH is the greatest. Because, Ageing for long period should change the amorphous iron hydroxides is considerably less than that in usual atmospheric corrosion products. The concentration of chlorine and sulfine is remarkably variable ($Cl^-$ : 100- 30,000ppm, $SO_4^-2$ : 20-10,000ppm),but the reasons are unclear. The presence of generally high concentrations of chlorine and sulfine the corrosion products of iron objects seem to be influenced by the marine climatic condition. The presence of high chlorine and sulfine concentrations in the corrosion products of iron objects seem to be influenced by the marine burial environments.

• Corrosion Science and Technology
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• v.7 no.2
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• pp.119-124
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• 2008

Steel is generally not corrosion resistant to water with formation of non protective rusts on its surface. Rusts are composed of iron oxides such as $Fe_3O_4$, $\alpha-$, $\beta-$, $\gamma-$and ${\delta}-FeOOH$. However, steel, particularly weathering steel containing small amounts of Cu, Ni and Cr etc., shows good corrosion resistance against rural, industrial or marine environment. Its corrosion rate is exceedingly small as compared with that of carbon steel. According to the exposure test results undertaken in outdoor environments, the atmospheric corrosion rate for weathering steel is only 1 mm for a century. Atmospheric corrosion for steels proceeds under alternate dry and wet conditions. Dry condition is encountered on steel surface on fine or cloudy days, and wet condition is on rainy or snowy days. The reason why weathering steel shows superior atmospheric corrosion resistance is due to formation of corrosion protective rusts on its surface under very thin water layer. The protective rusts are usually composed of two layer rusts; the upper layer is ${\gamma}-FeOOH$ termed as lepidocrocite, and inner layer is nano-particle ${\alpha}-FeOOH$ termed as goethite. This paper is aimed at elucidating the atmospheric corrosion mechanism for steel in comparison with corrosion in bulky water environment by use of empirical data.The summary is as follows: 1. No corrosion protective rusts are formed on steel in bulky water. 2. Atmospheric corrosion for steel is the corrosion under wetting and drying conditions. Corrosion and passivation occur alternately on steel surface. Steel, particularly weathering steel with small amounts of alloying elements such as Cu, Ni and Cr etc. enhances forming corrosion protective rusts by passivation.

• Environmental Analysis Health and Toxicology
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• v.23 no.2
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• pp.119-127
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• 2008

The purpose of this study was to investigate the effects of frankincense oil in a skin aging animal model. Skin aging was induced by both the irradiation of UVB and the application of squalene monohydroperoxide (Sq-OOH) to the back of experimental animals for 4 weeks. And at the same time experimental materials were applied topically. Six to seven weeks female SHR-1 hairless mice were divided into five groups including normal (N: saline), control (C: UVB+Sq-OOH+saline), vehicle control (VC: UVB+Sq-OOH+jojoba oil), positive control (PC: UVB+Sq-OOH+0.01% retinoic acid) and experimental (E: UVB+Sq-OOH+3% Frankincense oil) groups, five animals each group. The skin erythema index for the PC and E groups were lower than that of the C group. Whereas, both the lipid and water capacities for the PC and E groups were higher than those of the C group. Wrinkles for the C group were formed as a pattern of deep furrows and thick crests. Whereas, wrinkles for the PC and E groups were formed as a pattern of shallow furrows and thin crests which were similar to that of the N group. As for the both absolute and relative weight of the spleen, the PC group were significantly higher than the other groups. In conclusion, frankincense oil can be used practically for the prevention or improvement of skin aging in terms of health promotion and beauty for the people.