• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.4
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• pp.318-323
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• 2000

The intercalated compounds of alkylsulfonates into hydrated zinc were synthesized. From the high temperature powder X-ray diffraction (HTXRD), FT-IR, and molecular size, the temperature dependence of orientation for the intercalated alkylsulfonates were determined. In the temperatures range 1, alkylsulfonates were intercalated into hexa aqua zinc layer with the bilayer structure of $32.9^{\circ}$angle for ${Zn(H_2O_4]^{2+}[C_nH_{2n+1}SO_3]_2\;^-$. In the temperatures range 2, alkylsulfonates were intercalated into tetra aqua zinc layer with the bilayer structure of $55.2^{\circ}$angle for ${Zn(C_nH_{2n+1}SO_3)_2$. In the temperatures range 3, alkylsulfonates were directly bonded to zinc ion with the bilayer structure of $76.5^{\circ}$angle for ${Zn(C_nH_{2n+1}SO_3)_2$.

• Journal of the Korean Chemical Society
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• v.9 no.1
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• pp.16-22
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• 1965

The time-lag-effect of alkali salts on the gelation of sodium alginate-$CaSO_4{\cdot}$1/2 $H_2O$ is compared with Miyake's data, and then the formation rate of the elastics measured by the continuous method (an improved Schwedoff's method) and the change of rigidity with metallic oxides are studied as follows: (1) The gelation processes of sodium alginate and $CaSO_4{\cdot}$1/2 $H_2O$-aqueous sol are studied by measuring, continuously the increases of tensions ofsamples. (2) The time-lag-effect of $Na_3PO_4$ on the formation rate of the elastic gel is larger than that of $Na_2CO_3$, but the difference between the effects of the two alkali salts on the rate is found not so greater than predicted in Miyake's data. (3) Any regularities of the effect on the rate by metallic oxides are not observed. The increasing effects of the rates of $SiO_2$ and MgO are relatively large, and that of ZnO is relatively small. However, $Al_2O_3$, $Sb_2O_3$ and $TiO_2$show some decreasing effects. As a result it is noted that the regularities do not depend on the effect of oxide species and their amounts. (4) It is not found proportionality between the rigidity and the gelation rate. However, the increasing effect of the rigidity with the addition of metallic oxides can be observed. The rigidity increasing rate of MgO is the largest of them.

• Korean Journal of Materials Research
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• v.6 no.9
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• pp.943-949
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• 1996

카올린에서 추출된 황산알루미늄 용액으로부터 촉매담체용 r-AI2O3분말 합성에 대하여 연구하였다. 황산알루미늄 용액을 교반중의 에탄올(ethanol)에 적하하여 단일상(single phase)의 AI2(So4)3 18H2O석출물을 제조하고 이 석출물의 하소로부터 r-AI2O3분말을 합성하였다. 이 분말을 100$0^{\circ}C$에서 2시간 하소하였을 때 열적안정성을 보였으나, 120$0^{\circ}C$-2시간 하소에서 $\alpha$-AI2O3 로 전이하였다. r-AI2O3의 열적안정성에 미치는 BaO 첨가의 영향을 조사 연구하였다. 첨가량은 r-AI2O3에 대해서 1.0-6.0wt%로 하였다. BaO를 4.0wt%첨가한 시료는 AI2O3-BaO.6AI2O3(hexa-aluminate)혼합상생성으로 인하여 120$0^{\circ}C$에서 r-AI2O3의 전이를 방지하는데 효과적이었다. BaO를 4.0wt%첨가한 시료와 BaO를 첨가하지 않은 시료에 대하여 r-AI2O3$\longrightarrow$ $\alpha$-AI2O3전이에 따른 비표면적을 조사하여 보았다. 120$0^{\circ}C$-2시간에서 BaO 4.0wt% 첨가한 시료와 BaO를 첨가하지 않은 시료의 비표면적은 각각 95$m^2$/g과 50$m^2$/g을 유지하였다.

• Clean Technology
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• v.26 no.4
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• pp.304-310
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• 2020

In order to apply a photocatalyst (TiO2) to various building materials, TiO2-mayenite was prepared in this study. The TiO2 was synthesized using the sol-gel method by fixing titanium isopropoxide (TTIP) and urea at a ratio of 1 : 1. Later, they were calcined in a temperature range of 400-700 ℃ to analyze the properties according to temperature. BET, TGA, and XRD were used to analyze the physical and chemical properties of TiO2. The nitrogen oxide removal test was confirmed by measuring the change in the concentration of NO for 1 h according to KS L ISO 22197-1. The prepared TiO2 samples exhibited an anatase crystal structure below 600 ℃, and TiO2 (urea)-400 showed the highest nitrogen oxide removal rate at 2.35 µmol h-1. TiO2-mayenite was prepared using two methods: spraying TiO2 dispersion solution (s/s) and sol-gel solution (g/s). Through BET and XRD analysis, it was found that 5-TiO2 (g/s) prepared by spraying a sol-gel solution has maintained its crystallinity even after heat treatment. Also, 5-TiO2 (g/s)-500 showed the highest removal rate of 0.55 µmol h-1 in the nitrogen oxide removal test. To prepare TiO2-mayenite, it was confirmed that mayenite should be blended with TiO2 in a sol-gel state to maintain the crystal structure and exhibit a high nitrogen oxide removal rate.

• Solar Energy
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• v.10 no.2
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• pp.69-76
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• 1990

Photoelectrochemical decomposition of water by the irradiation of light to the $TiO_2$ thin film soaked in water was observed. The $TiO_2$ thin film was coated on top of $SnO_2$ nesa glass by use of spray method and of dip-coating method. The spray technique of $SnO_2$ nesa film production and dip-coating technique of $TiO_2$ thin film preparation on top of the $SnO_2$ nesa film were discribed briefly. $TiO_2$ film appearance was observed by SEM and I-V characteristic curve were measured for the various thickness of $TiO_2$ film. The film Thickness $1.8{\mu}m$ showed the maximum photoelectric current. Xe-lamp was used as light source for the photoelectrochemical reaction of thin film $TiO_2$ in acidic water(pH=1)

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.63.1-63.1
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• 2013

We present the results of time monitoring observations of $^{28}SiO$ v = 1, 2, J = 1-0, $^{29}SiO$ v = 0, J = 1-0 and $H_2O$ $6_{16}-5_{23}$ maser lines toward radio Source I in Orion KL. The observations have been performed from 2009 June to 2013 April using the 21m single dish radio telescopes of the Korean VLBI Network. Both SiO and $H_2O$ maser lines were simultaneously obtained at 20 epochs. In particular, the third outburst of $H_2O$ maser emission (the first: 1985, the second: 1998) was detected and the flux density variation curve was obtained. The maximum flux density flared up to an order of $10^5$ Jy during 2012 May-July at peak velocity of 7.33 km $s^{-1}$. Hirota et al. (2011) reported that the bursting maser features are located at 8" from Source I and coincident with the interacting region between the outflow from Source I and a dense ambient gas, Orion Compact Ridge. In the case of SiO masers arising from close to the Source I, the peak emission of the v = 1, J = 1-0 maser line appeared in 2010 April. We are investigating the possible relation between this SiO maser peak emission and the third $H_2O$ maser flaring.

• Journal of the Korean Ceramic Society
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• v.19 no.3
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• pp.193-198
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• 1982

The vaporization of $MgFe_2O_4$ was studied in $H_2-CO_2$ atmosphere over the temperature range of 600 to 90$0^{\circ}C$ by means of the transpiration method. It was found that the rate of vaporization for $MgFe_2O_4$ is controlled by a first order phase-boundary chemical reaction. The obtained activation energy of vaporization is 17.1 Kcal/mol.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.1147-1149
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• 1993

ZnO/$SnO_2$:F bilayer films have been prepared by pyrosol deposition method to develop optimum transparent electrode for use in amorphous silicon solar cells. The solution for $SnO_2:F$ film was composed of $SnCl_4{\cdot}5H_2O,\;NH_4F,\;CH_3OH$ and HCl, and ZnO films have been deposited on the $SnO_2:F$ films by using the solution of $ZnO(CH_3COO){_2}{\cdot}2H_2O,\;H_2O\;and\;CH_3OH$. These films have been investigated the variation of electrical and optical properties under the hydrogen plasma exposure. The sheet resistance of the $SnO_2:F$ film was sharply increased and its transmittance was decreased with the blackish effect after plasma treatment. However, the ZnO/$SnO_2:F$ bilayer film was shown hydrogen plasma durability because the electrical and optical properties was almost unchanged more then 60 seconds exposure time.

• Journal of the Korean Solar Energy Society
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• v.23 no.4
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• pp.29-35
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• 2003

We studied the water splitting into $H_2$ and $O_2$ using two different semiconductor photo catalysts and redox mediator, mimicking the Z-scheme mechanism of the photosynthesis, $H_2$ evolution took place on a Pt-$SrTiO_2$ (Cr-Ta doped) photocatalyst using $I^-$ electron donor under the visible light irradiation. The Pt-$WO_3$ photocatalyst showed an excellent activity of the $O_2$ evolution using $IO_3^-$ electron acceptor under visible light. $H_2$ and $O_2$ gases evolved in the stoichiometric ratio($H_2/O_2$=2) under visible light using a mixture of the Pt-$WO_3$ and Pt-$SrTiO_3$ (Cr-Ta doped) suspended in NaI aqueous solution. We proposed a two-step photo-excitation mechanism using redox mediator under the visible irradiation.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2000.04a
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• pp.110-111
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• 2000

대기중 가스상 $H_2O_2$(Hydrogen Peroxide)는 액상 화학반응과 기상 라디칼반응사이에 연결고리의 역할을 할 뿐만 아니라, 대기중의 $SO_2$를 $H_2SO_4$로 산화시키는 산화제로서 구름, 안개, 이슬 및 빗물의 산화에 중요한 역할을 담당한다. 또한 가스상 $H_2O_2$는 연쇄종결자와 $HO_2$.(hydroperoxyl radical)농도의 지표로서 광화학 스모그에 있어 중요한 화학종이기도 하다. $H_2O_2$농도의 증가는 결국 대기의 산화율 및 속도를 증가시키고 대류권내의 액상중에서 $H_2SO_4$ 생성을 가속화시킨다는 것은 이미 잘 알려져 있는 사실이다. (중략)