• Korean Journal of Materials Research
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• v.22 no.11
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• pp.620-625
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• 2012

A general synthetic method to make $Fe_3O_{4-{\delta}}$ (activated magnetite) is the reduction of $Fe_3O_4$ by $H_2$ atmosphere. However, this process has an explosion risk. Therefore, we studied the process of synthesis of $Fe_3O_{4-{\delta}}$ depending on heat-treatment conditions using $FeC_2O_4{\cdot}2H_2O$ in Ar atmosphere. The thermal decomposition characteristics of $FeC_2O_4{\cdot}2H_2O$ and the ${\delta}$-value of $Fe_3O_{4-{\delta}}$ were analyzed with TG/DTA in Ar atmosphere. ${\beta}-FeC_2O_4{\cdot}2H_2O$ was synthesized by precipitation method using $FeSO_4{\cdot}7H_2O$ and $(NH_4)_2C_2O_4{\cdot}H_2O$. The concentration of the solution was 0.1 M and the equivalent ratio was 1.0. ${\beta}-FeC_2O_4{\cdot}2H_2O$ was decomposed to $H_2O$ and $FeC_2O$4 from $150^{\circ}C$ to $200^{\circ}C$. $FeC_2O4$ was decomposed to CO, $CO_2$, and $Fe_3O_4$ from $200^{\circ}C$ to $250^{\circ}C$. Single phase $Fe_3O_4$ was formed by the decomposition of ${\beta}-FeC_2O_4{\cdot}2H_2O$ in Ar atmosphere. However, $Fe_3C$, Fe and $Fe_4N$ were formed as minor phases when ${\beta}-FeC_2O_4{\cdot}2H_2O$ was decomposed in $N_2$ atmosphere. Then, $Fe_3O_4$ was reduced to $Fe_3O_{4-{\delta}}$ by decomposion of CO. The reduction of $Fe_3O_4$ to $Fe_3O_{4-{\delta}}$ progressed from $320^{\circ}C$ to $400^{\circ}C$; the reaction was exothermic. The degree of exothermal reaction was varied with heat treatment temperature, heating rate, Ar flow rate, and holding time. The ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was greatly influenced by the heat treatment temperature and the heating rate. However, Ar flow rate and holding time had a minor effect on ${\delta}$-value.

• Korean Journal of Crystallography
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• v.15 no.1
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• pp.35-39
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• 2004

Two new nickel vanadium borophosphate cluster compounds, $(NH_4)_{10}[Ni(H_2O)_5]_4[V_2P_2BO_{12}]_6{\cdot}nH_2O$ (1) and $(NH_4)_{3.5}(C_3H_{12}N_2)_{3.5}[Ni(H_2O)_6]_{1.25}{[Ni(H_2O)_5]_2[V_2P_2BO_{12}]_6{\cdot}nH_2O$ (2) have been synthesized and structurally characterized. Inter-diffusion methods were employed to prepare the compounds. The cluster anion $[(NH_4)\;{\supset}\;V_2P_2BO_{12}]_6$ is used as a building unit in the synthesis of new compounds containing $Ni(H_2O){^{2+}_5}$ in the presence of pyrazine and 1,3-diaminopropane. Compounds contain isolated cluster anions with general composition ${[Ni(H_2O)_5]_n[(NH_4)\;{\supset}\;V_2P_2BO_{12}]_6}^{-(17-2n)}$ (n = 2, 4). Crystal data: $(NH_4)_{10}[Ni(H_2O)_5]_4[V_2P_2BO_{12}]_6{\cdot}nH_2O$, monoclinic, space group C2/m (no. 12), a = 27.538(2) ${\AA}$, b = 20.366(2) ${\AA}$, c = 11.9614(9) ${\AA}$, ${\beta}$ = 112.131(1)$^{\circ}$, Z = 8; $(NH_4)_{3.5}(C_3H_{12}N_2)_b[Ni(H_2O)_6]_{3.5}{[Ni(H_2O)_5]_2[V_2P_2BO_{12}]_6{\cdot}nH_2O$, triclinic, space group P-1 (no. 2), a = 17.7668(9) ${\AA}$, b = 17.881(1) ${\AA}$, c = 20.668(1) ${\AA}$, ${\alpha}$ = 86.729(1)$^{\circ}$, ${\beta}$ \ 65.77(1)$^{\circ}$, ${\gamma}$ = 80.388(1)$^{\circ}$, Z = 2.

• Journal of the Korean Chemical Society
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• v.15 no.6
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• pp.312-317
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• 1971

The interactions of aniline, o-toluidine, o-ethylaniline and o-chloroaniline with iodine in carbon tetrachloride solution have been examined through spectrophotometric measurements. The results indicate that both aniline and the o-substituted anilines examined form one-to-one complexes with I2in solution. The formation constants of the complexes measured at room temperature are 12.8, 9.31, 3.15 and 0.576 l $mole^{-1}$, respectively. Comparison of these results with previous experimental results indicates that the relative stabilities of the $I_2$-amine complexes decrease in the following order: $C_6H_5N(C_2H_5)_2 >C_6H_5N(CH_3)_2 >C_6H_5NH_2 >o-CH_3C_6H_4NH_2 >o-C_2H_5C_6H_4NH_2 >o-ClC_6H_4NH_2$. This may support the conclusion that the relative stabilities of these complexes are explained by the inductive effect and steric hindrance of the substituents.

• Nuclear Engineering and Technology
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• v.16 no.2
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• pp.58-63
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• 1984

Paper electrophoretic separation of octahedrally bonded (Ruc $l_{6}$ )$^{3-}$ has been carried out by using the specially designed migration apparatus. The supporting electrolyte solutions are as follows: 0.1M-HCl $O_4$, 0.05 M-HCl+0.09M-KCl, 0.1M-HCl, 5$\times$10$^{-3}$ M-NTA, 0.01M-HCl, 0.01M-HCl $O_4$, 0.01M-citric acid, 0.01M-K $H_2$P $O_4$+0.01M-N $a_2$HP $O_4$, 0.05M-borax, 0.025M-N $a_2$C $O_3$+0.025M-NaHC $O_3$, 0.01M-N $a_3$P $O_4$, 0.01M-NaOH and 0.1 M-NaOH. The (Ruc $l_{6}$ )$^{3-}$ appears in 2 to 4 peaks and is found in several chemical species such as (RuCl ($H_2O$)$_{5}$ )$^{2+}$, cis and trans (RuC $l_2$($H_2O$)$_4$)$^{1+}$, (RuC $l_3$($H_2O$)$_3$)$^{0}$ , (RuC $l_4$($H_2O$)$_2$)$^{1-}$, (RuC $l_{5}$ ($H_2O$))$^{2-}$ and (RuC $l_{6}$ )$^{3-}$. The retention value has been found to be highest in the 0.025M-N $a_2$C $O_3$+0.025M-NaHC $O_3$ electrolyte solution.n.

• Journal of the Korean Chemical Society
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• v.24 no.3
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• pp.218-224
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• 1980

The surface reactions of CO and $C_2H_4$ with adsorbed oxygen on ZnO were studied by means of EPR spectroscopy. The EPR spectra of $O_2$ adsorbed ZnO at various temperatures were compared, and the signal at g = 2.014 was characterized as trapped $O^-$ at oxygen vacancy. CO and $C_2H_4$ react with $O^-$ at $25^{\circ}C$ and desorbed as $CO_2$ and $H_2O$ above $200^{\circ}C$. $O_2^-$ species interact with $C_2H_4$ about $100^{\circ}C$, but desorption of partial oxidation products also was not observed until the temperature was raised to $200^{\circ}C$.

• Journal of the Korean Ceramic Society
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• v.35 no.12
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• pp.1336-1336
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• 1998

A twt -step carbothermal reduction scheme has been employed for the synthesis of SiC whiskers in an Ar or a H2 atmosphere via vapor-solid two-stage and vapor-liquid-solid growth mechanism respectively. It has been shown that the whisker growth proceed through the following reaction mechanism in an Ar at-mosphere : SiO2(S)+C(s)-SiO(v)+CO(v) SiO(v)3CO(v)=SiC(s)whisker+2CO2(v) 2C(s)+2CO2(v)=4CO(v) the third reaction appears to be the rate-controlling reaction since the overall reaction rates are dominated by the carbon which is participated in this reaction. The whisker growth proceeded through the following reaction mechaism in a H2 atmosphere : SiO2(s)+C(s)=SiO(v)+CO(v) 2C(s)+4H2(v)=2CH4(v) SiO(v)+2CH4(v)=SiC(s)whisker+CO(v)+4H2(v) The first reaction appears to be the rate-controlling reaction since the overall reaction rates are enhanced byincreasing the SiO vapor generation rate.

• Korean Journal of Materials Research
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• v.22 no.5
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• pp.253-258
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• 2012

Activated magnetite ($Fe_3O_{4-{\delta}}$) was applied to reducing $CO_2$ gas emissions to avoid greenhouse effects. Wet and dry methods were developed as a $CO_2$ removal process. One of the typical dry methods is $CO_2$ decomposition using activated magnetite ($Fe_3O_{4-{\delta}}$). Generally, $Fe_3O_{4-{\delta}}$ is manufactured by reduction of $Fe_3O_4$ by $H_2$ gas. This process has an explosion risk. Therefore, a non-explosive process to make $Fe_3O_{4-{\delta}}$ was studied using $FeC_2O_4{\cdot}2H_2O$ and $N_2$. $FeSO_4{\cdot}7H_2O$ and $(NH_4)_2C_2O_4{\cdot}H_2O$ were used as starting materials. So, ${\alpha}-FeC_2O_4{\cdot}2H_2O$ was synthesized by precipitation method. During the calcination process, $FeC_2O_4{\cdot}2H_2O$ was decomposed to $Fe_3O_4$, CO, and $CO_2$. The specific surface area of the activated magnetite varied with the calcination temperature from 15.43 $m^2/g$ to 9.32 $m^2/g$. The densities of $FeC_2O_4{\cdot}2H_2O$ and $Fe_3O_4$ were 2.28 g/$cm^3$ and 5.2 g/$cm^3$, respectively. Also, the $Fe_3O_4$ was reduced to $Fe_3O_{4-{\delta}}$ by CO. From the TGA results in air of the specimen that was calcined at $450^{\circ}C$ for three hours in $N_2$ atmosphere, the ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was estimated. The ${\delta}$-value of $Fe_3O_{4-{\delta}}$ was 0.3170 when the sample was heat treated at $400^{\circ}C$ for 3 hours and 0.6583 when the sample was heat treated at $450^{\circ}C$ for 3 hours. $Fe_3O_{4-{\delta}}$ was oxidized to $Fe_3O_4$ when $Fe_3O_{4-{\delta}}$ was reacted with $CO_2$ because $CO_2$ is decomposed to C and $O_2$.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.1B
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• pp.93-100
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• 2011

The people frequently drink coffee under stress at work, according to increase attractive of leisure activities, favourite food in modern society. The coffee taste which we are catching the taste of modern people is depending on various kinds processing methods such as a mixture of beans. However, the most coffee contains $C_8H_{10}O_2N_4$ which affected various parts of the body. These $C_8H_{10}O_2N_4$, is that the main component of coffee is caffeine. Therefore, in this paper, we are analyzed influence about articulator according to increase in $C_8H_{10}O_2N_4$ 250mg contains a cup of coffee. From this, we gradually increased the amount of $C_8H_{10}O_2N_4$ intake about thirty persons of men in his 20's in experiments. Then we performed a study about Jitter, Formant, Spectrum in voice analysis parameter by applying the results having an affect articulator.

• Journal of the Korean Chemical Society
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• v.9 no.2
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• pp.71-74
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• 1965

Reduction of Ti(Ⅳ)-oxalate complex on dropping mercury electrode has been studied as a function of oxalate concentration and of pH varied with HCl. Assuming there are equilibrium $TiO(C_2O_4)_2= \;+\;2H^+\;=\;Ti^{+4}\;+\;2C_2O_4\;=\;+\;H_2O,\;K_4$ in addition to $TiO(C_2O_4)_2\;^=\;=\;TiO^{++}\;+\;2C_2O_4=\;K_2\;Ti(C_2O_4)_2\;^-\;=\;Ti^{+3}\;+\;2C_2O_4=\;K_3$ in the system cathodic wave has been well explained for that pH is higher than 0.5. The equilibrium constants $K_2,\;K_3$ and $K_4$ have been to be $2{\times}10^{-12},\;5{\times}10^{-13}$ and $10^{-11}$, respectively. The reduction of Ti(Ⅳ)-oxalate system is $Ti^{+4}\;+\;e\;{\to}\;Ti^{+3}$ in the concentration of hydrochloric acid, higher than 3M.

• Bulletin of the Korean Chemical Society
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• v.26 no.10
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• pp.1525-1528
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• 2005

The synthesis and characterization of ${K_3[Ru(C_2O_4)3]{\cdot}4H_2O\;(C_2O_4}^{2-}$ = oxalato anoin) complex are described, and its redox properties (in buffer solution of pH = 12) have been investigated. This complex is used for in situ generation of oxoruthenates complexes which have been characterized by electronic spectroscopy. Reaction of ${K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${S_2O_8}^{2-}$ in molar KOH generates trans-${[RuO_3(OH)_2]^{2-}/S_2O_8}^{2-}$ reagent while with excess ${BrO_3}^-$ in molar $Na_2CO_3$ generates ${[RuO_4]^-/BrO_3}^-$ reagent. Avoiding the direct use of [$RuO_4$] the organic-soluble $(n-Pr_4N)^+[RuO_4]^-$, (TPAP) has been isolated by reaction of $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${BrO_3}^-$ in molar carbonate and n-$Pr_4$NOH. In a mixture of $H_2O/CCl_4$ ruthenium tetraoxide can be generated by reaction of $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ with excess ${IO_4}^-$. The catalytic activities of oxoruthenates that have been made from $K_3[Ru(C_2O_4)3]{\cdot}4H_2O$ towards the oxidation of benzyl alcohol, piperonyl alcohol, benzaldehyde and benzyl amine at room temperature have been studied.