• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.394-397
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• 2008

In this research, the fine-structure TiO2+Ti bulks have been fabricated by the combined application of magnetic pulsed compaction (MPC) and subsequent sintering, and their densification behavior was investigated. The obtained density of $TiO_2$+Ti bulk prepared by the combined processes was increased with increasing MPC pressure from 0.7 to 1.7 GPa. Relatively higher density (88%) in the MPCed specimen at 0.7Gpa was attributed to the decreasing of the inter-particle distance of pre-compacted component. High pressure and rapid compaction by Magnetic Pulsed Compaction could reduce shrinkage rate (about 10%) of the sintered bulks compared to that of general processing (about 20%). Mixing conditions of PVA, water, Ti and $TiO_2$ nano powder for compaction of $TiO_2$ nano powder did not affect on density and shrinkage of the sintered bulks due to high pressure of MPC.

• Korean Journal of Materials Research
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• v.26 no.8
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• pp.406-411
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• 2016

In order to reuse the photocatalyst and enhance the photolysis efficiency, we have used atmospheric pressure dielectric barrier discharge (APDBD) to clean and activate $TiO_2$ powder. The photocatalytic activity of the $TiO_2$ powder before and after APDBD treatment was evaluated by the degradation of methylene blue (MB) in aqueous solution. The apparent reaction rate constant of photolysis of the first sample of reused $TiO_2$ cleaned by APDBD improved to a level up to 0.32h-1 higher than the 30 % value of the initial $TiO_2$ powder. As the number of photolysis reactions and APDBD cleanings increased, the apparent rate constants gradually decreased; however, the fourth photolysis reaction still showed a value that was greater than 10% of the initial value. In addition, APDBD treatment enhanced the process by which $TiO_2$ effectively adsorbed MB at every photolysis stage.

• Journal of Powder Materials
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• v.24 no.4
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• pp.279-284
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• 2017

The formation mechanism and photocatalytic properties of a multiwalled carbon nanotube (MWCNT)/$TiO_2$-based nanotube (TNTs) composite are investigated. The CNT/TNT composite is synthesized via a solution chemical route. It is confirmed that this 1-D nanotube composite has a core-shell nanotubular structure, where the TNT surrounds the CNT core. The photocatalytic activity investigated based on the methylene blue degradation test is superior to that of with pure TNT. The CNTs play two important roles in enhancing the photocatalytic activity. One is to act as a template to form the core-shell structure while titanate nanosheets are converted into nanotubes. The other is to act as an electron reservoir that facilitates charge separation and electron transfer from the TNT, thus decreasing the electron-hole recombination efficiency.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.469-470
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• 2006

[ $TiO_2$ ] nanoparticle was synthesized by the flame method, which was controlled by varying the ratio and flow rate of gas mixtures consisting of oxygen (oxidizer), methane (fuel) and nitrogen (carrier gas). The crystalline phases of $TiO_2$ nanoparticle depended strongly on the temperature distribution in the flame, whereas the morphology was not sensitive. We proved that the anatase phase formed without the phase transformation in the flame and the rutile phase generated through several phase transformations.

• Proceedings of the Korean Ceranic Society Conference
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• 2000.04a
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• pp.144.2-144.2
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• 2000

• Proceedings of the Materials Research Society of Korea Conference
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• 1993.11a
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• pp.2-2
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• 1993

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.178-178
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• 2002

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.28-32
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• 1998

Two organophosphorous insecticides, Dichlorovos and Chloropyrifos were degraded in the presence of UV irradiation, UV irradiation with $TiO_2$ powder and UV irradiation with sea sand using low pressure mercury lamp. The identification of these compounds was carried out by gas chromatograph with a nitrogen-phosphorous detector, Total Organic Carbon and Ion Chromatograph, respectively. Both dichlorvos and chloropyrifos, UV irradiation with sea sand were more degradable than UV irradiation and UV irradiation with $TiO_2$ powder. The final products were $Cl^-$ in Dichlorvos, $Cl^-$ $SO_4{^{2-}}$ in Chloropyrifos, respectively.

• Journal of Powder Materials
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• v.10 no.1
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• pp.15-20
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• 2003

Hybrid $A1_2O_3-TiC$ ceramic particle reinforced 6061 and 5083 Al composite powders were prepared by the combination of twin rolling and stone mill crushing process, followed by consolidating processes of cold compaction, degassing and hot extrusion. The composite bar consists of lamellar structure of ceramic particle rich area and matrix area, in which the hybrid was decomposed into each TiC of about $3-4\mutextrm{m}$ and $AI_2O_3$ particles of about $1-2\mutextrm{m}$ in diameter. It also found that fine $Mg_2Si$ precipitates of about 30 nm were embedded in the matrix, which have grains of about 3 $\mutextrm{m}$. Higher UTS was measured at the 5083 composite bar compared to the conventionally fabricated composite, due to again refinement effect by the rapid solidification. No particle was shown to form in the interface between the matrix and reinforcement, whereas carbon was diffused into the matrix.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.288-288
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• 2007

본 연구에서 내환원성 $BaTiO_3$의 PTCR(Positive Temperation Coefficient Resistance) 특성 및 미세구조에 대한 분쇄 및 출발 원료들의 하소 조건의 영향을 연구하였다. $BaCO_3$, $TiO_2$, $CeO_2$를 Attrition milling 하여 1차 혼합 및 분쇄한 후 건조하여 혼합분말을 얻었으며, $(Ba_{1-x}Ce_x)TiO_3$를 합성하기 위하여 $1000^{\circ}C{\sim}1200^{\circ}C$ 공기중에서 하소하였다. 각 하소온도에서 제조한 $(Ba_{1-x}Ce_x)TiO_3$에 첨가제를 2차 혼합하고 초미분쇄하여 분말을 제조하였다. 직경 5mm 의 시편을 제조하여 환원 및 재산화 분위기에서 소결을 한 후 상온저항값 및 R-T특성을 측정하였고 SEM 을 통해 미세구조를 관찰하였다. 또한 하소 후 온도에 따른 상분석을 XRD를 통하여 분석하였다. 그 결과 하소온도가 증가함에 따라 상온저항값은 감소하는 경황을 보였으며 PTC특성은 감소하다가 증가하는 경향을 보였다. 초미분쇄에 따른 입자크기는 $1{\mu}m$이하로 작아졌으며 미립화가 됨에 따라 하소/소결온도에 앙향을 줄 것으로 사료된다.