• Korean Journal of Materials Research
• /
• v.5 no.6
• /
• pp.706-714
• /
• 1995

Silicon oxide thin films were deposited by remote plasma chemical vapor deposition (RPCYD). The effect of the operating variables, such as plasma power, deposition temperature and partial pressure of reactant on the material Properties of the silicon oxide film was investigated. By XPS, it was found out that the film was suboxide (O/Si<2) and small amount of nitrogen due to the plasma excitation was accumulated at the Si/SiO$_2$interface. The amount of dangling bonds at the Si/SiO$_2$interfaces were measured by ESR and the concentration of hydrogen bond was obtained by SIMS and FT-IR. The bond angle distribution(d$\theta$/$\theta$) was shown to be similiar to thermal oxide above 20$0^{\circ}C$ but the etch rate was higher than that of the thermal oxides due to the structural difference and the stress between silicon substrate and silicon oxide film.

• Korean Journal of Materials Research
• /
• v.9 no.12
• /
• pp.1263-1269
• /
• 1999

An FBAR(Solidly Mounted Resonator) was fabricated using reflector layers which prohibit the penetration of bulk acoustic wave into substrate. The SMR consisted of top and bottom electrodes(Al films), a piezoelectric layer (ZnO film), reflector layers(W/$Si_2$ films) and Si substrate. The electrodes were deposited by dc sputtering. The piezoelectric layer and the reflector layers were deposited by rf magnetron sputtering. The control of crystallinity, microstructures and electric properties of each layer was essential for attaining the optimum FBAR characteristics. Under the best deposition conditions for FBAR devices, the ZnO films had highly c-axis preferred orientation(${\sigma}=2.17^{\circ}$), resistivity of $10^4\;{\omega}cm$, and surface roughness of 10.6 ${\AA}$. On the other hand, the surface roughness of W and $Si_2$ films was 16 ${\AA}$ and 33 ${\AA}$, respectively, and the resistivity of Al film was $5.1{\times}10^{-6}\;{\Omega}cm$. The SMR devices were fabricated by the conventional semiconductor processes. In the resonance conditions of the SMR, the series resonance frequency (fs) and the parallel resonance frequency(fp) were 1.244 GHz and 1.251 GHz, respectively and the quality factor(Q) was 1200.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.12 no.4_1
• /
• pp.33-41
• /
• 1992

For the purpose of improving the strength of Concrete, Silica Fume which has $SiO_2$ content of 90% and average particle diameter of $0.2{\mu}m$ was substituted to some extent as a cementious material of concrete. By means of using high range water reducing admixture and reducing water-cementions material ratio, the high strength mortar and concrete which have compressive strength of $865kg/cm^2$, $725kg/cm^2$, respectively were acquired. But the fact that the slump loss according to elapsed time was high and the tensile strength and elastic modulus were not improved sufficiently was the problem to be solved.

• Membrane Journal
• /
• v.30 no.1
• /
• pp.1-8
• /
• 2020

In membrane bioreactor (MBR), activated sludge degrade the biological component and membrane process separate this bacterial flocks as well the suspended solids. However, membrane fouling is one of the major issues in MBR. In this review, composite membrane used in MBR to overcome fouling is discussed. It is classified into membrane containing carbon and noncarbon materials. Introducing graphene, graphene oxide (GO) and carbon nanotubes or their modified part into pristine membrane enhance hydrophilicity of the composite membrane. Inorganic materials like silicon dioxide (SiO₂) or titanium dioxide (TiO₂) are also incorporated for preparing composite membrane to increase its water flux.

• Korean Journal of Materials Research
• /
• v.15 no.5
• /
• pp.323-333
• /
• 2005

Effects of gases to growth of $SiO_2$ nanowires were characterized. $N_2$, Ar, and $O_2$ gas's effect were determined. $SiO_2$ nanowires growth scheme was varied by kind and flow rates of gases because of amounts of $O_2$. Flow rates of gases and kind of substrates affected nanowires' diameters, lengths and morphologies of grown nano wires. With increasing flow rates of gases, nanowire's diameter increased because of additional VS and SLS reactions. By TEM characterization, We knows that, grown $SiO_2$ nanowires on Si substrate showed two shell structures. These shapes of nanowires were formed by reaction of additional SLS growth. Grown $SiO_2$ nanowires showed blue luminescence by PL characterization These Blue luminescence was due to quantum confinement effect and oxygen vacancies in the nanowires.

• Korean Journal of Materials Research
• /
• v.15 no.3
• /
• pp.189-194
• /
• 2005

[ $SiO_2$ ] nanowires were synthesized using the catalyst evaporation method. Grown nanowires had different shapes by kind of used metal catalyst. Mean diameters of grown $SiO_2$ nanowire were about 30 nm. The kind of catalysts affected microstructure of grown $SiO_2$ nanowire because of its typical growth reactions through the liquid state metal catalysts. Optical property were measured by photoluminescence spectroscopy. Relatively broad peak was obtained and mean peak positioned at 450 nm.

• Transactions of the Korean hydrogen and new energy society
• /
• v.22 no.4
• /
• pp.415-423
• /
• 2011

HI decomposition step certainly demand catalytic reaction for efficient production of hydrogen in SI process. Platinum catalyst can apply to HI decomposition reaction as well as hydrogenation or dehydrogenation. Generally, noble metal is used as catalyst which is loaded form for getting high dispersion and wide active area. In this study, Pt was loaded onto zirconia, ceria, alumina, and silica by impregnation method. HI decomposition reaction was carried out under the condition of $450^{\circ}C$, 1atm, and $167.76h^{-1}$ (WHSV) in a fixed bed reactor for measuring catalytic activity. And property of a catalyst was observed by BET, TEM, XRD and chemisoption analysis. On the basis of experimental results, we discussed about conversion of HI according to physical properties of the loaded Pt catalyst onto each support.

• Journal of the Korean Applied Science and Technology
• /
• v.27 no.2
• /
• pp.183-187
• /
• 2010

Core-Shell polymers of silicone dioxide-styrene system were prepared by sequential emulsion polymerization. In inorganic/organic Core-Shell composite particle polymerization, silicone dioxide adsorbed by surfactant sodium dioctyl sulfosuccinate (EU-DO133L) was prepared initially and then core silicone dioxide was encapsulated emulsion by sequential emulsion polymerization using styrene at the addition of potassium persulfate (KPS) as an initiator. We found that $SiO_2$ core shell of $SiO_2$/styrene structure was formed when polymerization of styrene was conducted on the surface of $SiO_2$ particles, and the concentration sodium dioctyl sulfosuccinate (EU-DO133L) was 0.5~2.0g. The structure of core-shell polymer were investigated by measuring to the thermal decomposition of polymer composite using thermogravimetric analyzer and morphology of latex by scanning electron microscope(SEM).

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.129-129
• /
• 2011

냉음극 변압기 전원 소스를 이용하여 저진공에서 플라즈마를 발생시키는 시스템을 개발하였다. 또한 이 장치를 이용하여 도핑된 산화막 증착 기술을 연구하였다. 이 때 도핑 전구체는 액체 소스였으며 이를 기화시켜 사용하였다. 특히 p 타입이 도핑된 이산화규소 박막 증착을 상온에서 실시하였다. 공정 압력은 400~1,000 mT였으며, 전압은 약 1,100~2,100 V 범위에서 조절하였다. 증착된 박막은 박막 두께와 홀 측정을 실시하였다. 홀 측정을 위한 인듐 금속 접합을 400 C에서 실시하였다. 결과를 요약하면, 플라즈마 공정 압력이 400에서 1,000 mTorr로 증가함에 따라 박막 증착 속도는 약 240~440 ${\AA}$/min이었다. 또한 증착된 p-SiO2의 벌크 농도는 같은 압력 증가에 따라 약 $1.2{\times}10^{19}$에서 $6.5{\times}10^{18}/cm^3$으로 절반 정도 감소하였다. 그에 따라 도핑된 산화막의 비저항은 $~1.4{\times}10^{-3}$에서 $2.5{\times}10^{-3}{\Omega}{\cdot}cm$로 증가하였다. 홀 이동도는 약 380~400 $cm^2/V{\cdot}s$를 유지하였다. 또한 전압이 1,100 에서 2,100 V로 증가함에 따라 산화막의 증착 속도는 약 330에서 410 ${\AA}$/min으로 증가하였다. 그러나 전압이 증가해도 벌크 농도는 약 8,9~$6.6{\times}10^{18}/cm^3$의 범위였다. 보다 자세한 결과는 발표를 통해 설명할 것이다.

• Membrane Journal
• /
• v.19 no.4
• /
• pp.268-276
• /
• 2009

In this study the basic data were settled down to establish theory of membrane module and apparatus for measuring suspended solid per particle size. The theory and technique were different with the conventional weight method and light scattering method. For this purpose silica, dextran, kaolin, and PEG (polyethylene glycol) suspended solutions were filtrated through glass fiber membranes GF/C and GF/A on membrane module for measuring TMP (Trans-membrane pressure) changes using digital pressure gages. And the related equation between modified solution concentration and TMP change slope was derived from the TMP change experiments, and then suspended solid concentration of samples could be expected by the equation.