• 한국재료학회지
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• 제29권1호
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• pp.16-22
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• 2019

Indirect oxidation using chlorine species oxidizing agents is often effective in wastewater treatment using an electrochemical oxidation process. When chlorine ions are contained in the wastewater, oxidizing agents of various chlorine species are produced during electrolysis. In a ballast water management system, it is also used to treat ballast water by electrolyzing seawater to produce a chlorine species oxidizer. However, ballast water in the brackish zone and some wastewater has a low chlorine ion concentration. Therefore, it is necessary to study the chlorine generation current efficiency at various chlorine concentration conditions. In this study, the chlorine generating current efficiency of a boron-doped diamond(BDD) electrode and insoluble electrodes are compared with various chloride ion concentrations. The results of this study show that the current efficiency of the BDD electrode is better than that of the insoluble electrodes. The chlorine generation current efficiency is better in the order of BDD, MMO(mixed metal oxide), $Ti/RuO_2$, and $Ti/IrO_2$ electrodes. In particular, when the concentration of sodium chloride is 10 g/L or less, the current efficiency of the BDD electrode is excellent.

• 한국분말재료학회지
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• 제23권4호
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• pp.307-310
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• 2016

$TiOF_2$, which has remarkable electrochemical and optical properties, is used in various applications such as Li-ion batteries, electrochemical displays, and photocatalysts. In addition, it is possible to utilize the template which is allowed to synthesize fluorine doped $TiO_2$ powders with hollow or faceted structures. However, common synthesis methods of $TiOF_2$ powders have some disadvantages such as the use of expensive and harmful precursors and batchtype processes with a limited production scale. In this study, we report a synthetic route for preparing $TiOF_2$ powders by using an inexpensive and harmless precursor and a continuous ultrasonic spray pyrolysis process under a controlled atmosphere to address the aforementioned problems. The synthesized powder has an average size of $1{\mu}m$, a spherical shape, a pure $TiOF_2$ phase, and exhibits a band-gap energy of 3.2 eV.

• 대한전기학회논문지
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• 제41권6호
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• pp.652-660
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• 1992

0.10Pb(SbS11/2TSnS11/2T)OS13T-0.25PbTiOS13T-0.65PbZrOS13T ceramics modified by LaS12TOS13T(1[mol%]) and MnOS12T(0-0.30[mol%]) were fabricated. The structural and pyroelectric properties with contents of MnOS12T were studied. Crystal structure of a specimen was rhombohedral type and average grain sizes were decreased with increasing the contents of MnOS12T. Relative dielectric constant and dielectric loss factor were minimum in the specimens doped 0.24[mol%]MnOS12T. (PbS10.99TLaS10.01T)[(SbS11/2TSnS11/2T) TiS10.25TZrS10.65T]OS13T specimen modified 0.24[mol%]MnOS12T showed the good pyroelectric properties and pyroelectric coefficient and voltage responsivity were 6.73x10S0-8T[C/cmS02TK], 125[V/W], respectively. Voltage responsivity was increased with decreasing the chopper frequency.

• 센서학회지
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• 제13권2호
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• pp.152-156
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• 2004

The dielectric and piezoelectric properties of 0.36Pb($Sc_{1/2}Nb_{1/2}$)$O_{3}$-0.25Pb($Ni_{1/3}Nb_{2/3}$)$O_{3}$-0.39Pb$TiO_{3}$ (hereafter PSNNT) at the morphotropic phase boundary (MPB) composition were investigated with $0{\sim}2.5$ mot% $MnO_{2}$ doping. Bulk density, dielectric loss and tetragonality of crystal structure were all improved with increasing $MnO_{2}$ additive content. With increasing $MnO_{2}$ additive content, the electromechanical coupling factor and quality factor were also increased: Electromechanical coupling $k_{p}$ and quality factor $Q_{m}$ at 2.0 mol% $MnO_{2}$ doping with were showed highest values of 55.6 % and 252, respectively.

• 한국세라믹학회지
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• 제25권5호
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• pp.443-448
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• 1988

Colored Cubic Zircona(CCZ) single crystals were grown by the skull melting method. The grown crystals were doped with up to 0.1wt% transition (Cu, Ni, Co, Ti, Fe, Mo, Cr, V, Mn) metal ions on ZrO2-Y2O3(9.5~10mol%) and their Optical transmission spectra(λ=300~800nm)data were obtained. Various colors were pronounced due to dopant effects in the grown Crystals.

• 한국전기전자재료학회논문지
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• 제17권2호
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• pp.178-183
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• 2004

PBT thin film was known to be a representative for the FeRAM devices because of its good ferroelectric proporties and the ease in fabricating the thin film. However, there have been several problems such as polarization fatigue and leakage current in memory devices with a PZT thin film. In this study, Sm-dolled PZT thin films were fabricated by the so1-gel method, and their ferroelectric and dielectric proportrics were compared as a function of Sm content. We investigated the effect of the Sm dopant on structural and electrical properties of PZT film. Sm-doped PZT thin films on the Pt/Ti/SiO$_2$/Si substrates have been prepared by a sol-gel method. The remanent polarization and coercive field decreased with increasing the concentration of Sm. The dielectric constant and dielectric loss decreased with Increasing Sm content. Sm-doped PZT thin films showed improved fatigue characteristics compared to the undoped PZT thin film.

• 한국세라믹학회지
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• 제33권10호
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• pp.1101-1108
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• 1996

No-doped PZT thin films have been fabricated on Pt/Ti/SiO2/Si substrate using Sol-Gel technique. A fast annealing metho (three times of intermediate and final annealing) was used for the preparation of multi-coated 1800$\AA$ thick Nb-doped PZT thin films. As Nb doping percent was increased leakage current was lowered approximately 2 order but dielectic properties were degraded due to the appearance of pyrochlore phase and domain pinning. Futhermore the increase of the final annealing temperature up to 74$0^{\circ}C$lowered the pyrochlore phase content resulting in enhancing the dielectric properties of the Nb doped films. The 3%-Nb doped PZT thin films with 5% excess Pb showed a capacitance density of 24.04 fF/${\mu}{\textrm}{m}$2 a dielectric loss of 0.13 a switchable polarization of 15.84 $\mu$C/cm2 and a coercive field of 32.7 kV/cm respectively. The leakage current density of the film was as low as 1.47$\times$10-7 A/cm2 at the applied voltage of 1.5 V.

• 분석과학
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• 제24권6호
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• pp.493-502
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• 2011

본 연구에서는 가시광촉매의 특성을 나타낼 수 있는 촉매를 제조하여 촉매를 특성화 하였으며, toluene, xylene, MEK (methyl ethyl ketone), ammonia를 반응물로 하여 기존의 UV-광촉매와 분해능을 비교 실험하였다. UV-광촉매는 파장범위가 280~360 nm 근처에서 광촉매가 활성화된다. 그러나 가시광촉매는 가시광영역인 400~750 nm의 파장영역에서도 광촉매가 활성화 된다. 이것을 UV-Vis 흡수도로 파악하였다. 그리고 가시광촉매의 성능을 향상시키기 위하여 여러 가지 재료로 도핑하는데, 여기서는 망간에 Pt를 부가하여 성능향상을 꾀하였다. Pt를 첨가한 가시광 촉매의 경우 성능이 향상되었음을 알 수 있었다. 그리고 바인더로 MTMS (methyl tri methoxy silane)를 사용하였으며 바인더양에 따른 접촉각을 측정하였다. MTMS 함량이 증가할수록 접촉각이 커졌다. 따라서 친수성이 줄어든 것으로 나타났다. 그리고 Mn-$TiO_2$ 촉매의 항균성이 매우 우수한 것으로 나타났다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 C
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• pp.1254-1256
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• 1994

0.15$(Ba_{0.95}Sr_{0.05})$O-0.15$(Sm_{2(1-x)}Nd-{2x})O_3-0.7TiO_2 (x=0{\sim}10[m/o])$ ceramics were fabricated by mixed-oxide method. Microwave dielectric properties was investigated with the contents of $Nd_2O_3$. Increasing the contents of $Nd_2O_3$ from 0 to 6[m/o], sintered density was increased 5.53 to $5.68[g/ cm^3]$. In the specimen with contents of $Nd_2O_3$(6[m/o]), dielectric content was maximum value of 78.14 and decreased with increasing the contents of $Nd_2O_3$. Quality factor was increased with the contents of $Nd_2O_3$.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2016년도 추계학술대회 논문집
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• pp.199-199
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• 2016

Commercially pure titanium (cp-Ti) and Ti alloys (typically Ti-6Al-4V) display excellent corrosion resistance and biocompatibility. Although the chemical composition and topography are considered important, the mechanical properties of the material and the loading conditions in the host have, conventionally. Ti and its alloys are not bioactive. Therefore, they do not chemically bond to the bone, whereas they physically bond with bone tissue. The electrochemical deposition process provides an effective surface for biocompatibility because large surface area can be served to cell proliferation. Electrochemical deposition method is an attractive technique for the deposition of hydroxyapatite (HAp). However, the adhesions of these coatings to the Ti surface needs to be improved for clinical used. Plasma electrolyte oxidation (PEO) enables control in the chemical com position, porous structure, and thickness of the $TiO_2$ layer on Ti surface. In addition, previous studies h ave concluded that the presence of $Ca^{+2}$ and ${PO_4}^{3-}$ ion coating on porous $TiO_2$ surface induced adhesion strength between HAp and Ti surface during electrochemical deposition. Silicon (Si) in particular has been found to be essential for normal bone and cartilage growth and development. Zinc (Zn) plays very important roles in bone formation and immune system regulation, and is also the most abundant trace element in bone. The objective of this work was to study electrochemical characteristcs of Zn and Si coating on Ti-6Al-4V by PEO treatment. The coating process involves two steps: 1) formation of porous $TiO_2$ on Ti-6Al-4V at high potential. A pulsed DC power supply was employed. 2) Electrochemical tests were carried out using potentiodynamic and AC impedance methoeds. The morphology, the chemical composition, and the micro-structure an alysis of the sample were examined using FE-SEM, EDS, and XRD. The enhancements of the HAp forming ability arise from $Si/Zn-TiO_2$ surface, which has formed the reduction of the Si/Zn ions. The promising results successfully demonstrate the immense potential of $Si/Zn-TiO_2$ coatings in dental and biomaterials applications.