• Bulletin of the Korean Chemical Society
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• 제33권2호
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• pp.387-392
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• 2012

A series of Pd-based catalysts were prepared and examined for the amination of 2,6-dimethylphenol in a fixedbed reactor. The best results were obtained for Pd/$Al_2O_3$-BaO with a conversion of 99.89% and a selectivity of 91.16%. These catalysts were characterized using BET, XRD, XPS, TEM and $NH_3$-TPD. Doped BaO not only improved the dispersion of the Pd particles but also decreased the acidity of the catalyst, which remarkably enhanced the selectivity and stability of the catalyst. The generality of Pd/$Al_2O_3$-BaO for this kind of reaction was demonstrated by catalytic aminations of o- and p-alkyl phenols.

• 디지털융복합연구
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• 제12권7호
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• pp.291-296
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• 2014

GaN LED의 p-패드 금속과 에피층 사이에 $SiO_2$ 전류 절연 층을 제작하고, p-전극 금속의 패턴을 핑거(finger) 형태로 확장하여 형성함으로써, 대면적 고출력 소자에서 전류가 균일하게 퍼지도록 유도함과 동시에 p 패드 금속 표면에서의 광 손실을 줄여 광 출력을 증진시켰다. $SiO_2$ 절연 층의 면적과 두께를 다르게 하면서 광 출력의 증가를 비교 확인하였고, 실바코 사의 ATLAS 툴을 이용하여 컴퓨터 시뮬레이션을 실시함으로써 LED 내 활성 층에서의 전류 밀도 분포를 계산하였다. $SiO_2$ 절연 층의 두께가 $50{\mu}m$와 $100{\mu}m$ 인 두 경우 모두, p 패드의 직경이 $105{\mu}m$이고 핑거의 폭은 $12{\mu}m$인 경우와 비교할 때, p 패드의 직경이 $100{\mu}m$이고 핑거의 폭이 $6{\mu}m$인 경우가 더 높은 광 출력 특성을 나타냈다.

• 대한전자공학회논문지
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• 제16권1호
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• pp.19-23
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• 1979

$S_nO_2$ and $Z_nO$ based semiconductor combustible gas sensors have been fabricated and measured their charactcnstics. Adding about 0.5 wt % $P_dCf_2$ to the mixture of $S_n0_2$ and $Z_nO$ improved the sensitivity. The devices were fired for one hoar in air in the tewerature range of $400^{\circ}C$ to $1000^{\circ}C$. Their electrical conductivity was changed by t he change of atmosphenc pressure around then.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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• pp.76-79
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• 2004

This research was carried out to evaluate role of supplementary reagents, such as phosphate and SDS, to remove hydrophobic organic contaminant from soils during the EK-Fenton process. The $H_2O$$_2$ stability improved due to the role as stabilizer of phosphate and SDS during the EK-Fenton process. Furthermore, although pH in region near cathode was 8.2 after test, $H_2O$$_2$ stability improved due to transportation of SDS in the region near cathode. Therefore, in tests using phosphate and SDS as supplementary reagent, the efficiency of phenanthrene treatment improved through the EK-Fenton process using longer reaction time.

• 청정기술
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• 제21권4호
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• pp.271-277
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• 2015

본 연구에서는 효율적인 광 전기화학적 수소제조를 위하여 광촉매로써 상용화 촉매인 P25-티타니아와 합성한 Ag_xO를 적정 질량비로 혼합한 촉매를 사용하였다. Ag_xO는 일반적인 솔-젤법으로 합성하였으며, 은 용액의 안정화를 위해 합성과정 중에 수산화테트라메틸암모늄을 첨가하고 열처리 온도를 -5, 25, 50 ℃로 다양화시켜 세 가지 형태의 산화은을 얻었다. 합성한 Ag_xO의 물리화학적 특성은 X-선 회절분석법(XRD), 주사전자현미경(SEM), 자외선-가시선 분광광도계(UV-Visible spectroscopy), X-선 광전자 분광법(XPS)을 이용하여 확인하였다. 물/메탄올(무게 비 1:1) 혼합용액을 광분해 한 결과, 순수 P25-티타니아보다 Ag_xO가 첨가된 혼합촉매에서 현저히 높은 양의 수소가 발생하였다. 보조 산화제로써 H₂O₂를 첨가한 경우 그리고 Ag_xO의 합성온도가 50 ℃일 때 가장 높은 수소 제조효율을 나타내었다. 특히, 0.9 g의 P25-티타니아와 0.1 g의 Ag_xO (50 ℃)를 혼합한 촉매를 사용하였을 때 8시간 반응하는 동안에 13,000 μmol의 수소가 발생하였다.

• 센서학회지
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• 제29권3호
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• pp.156-161
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• 2020

In this study, hierarchical mesoporous CuO spheres, ZnO flowers, and heterojunction CuO/ZnO nanostructures were fabricated via a facile hydrothermal method. The as-prepared materials were characterized in detail using various analytical methods such as powder X-ray diffraction, micro Raman spectroscopy, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, and transmission electron microscopy. The obtained results are consistent with each other. The H₂S-sensing characteristics of the sensors fabricated based on the CuO spheres, ZnO flowers, and CuO/ZnO heterojunction were investigated at different temperatures and gas concentrations. The sensor based on ZnO flowers showed a maximum response of ~141 at 225 ℃. The sensor based on CuO spheres exhibited a maximum response of 218 at 175 ℃, whereas the sensor based on the CuO/ZnO nano-heterostructure composite showed a maximum response of 344 at 150 ℃. The detection limit (DL) of the sensor based on the CuO/ZnO heterojunction was ~120 ppb at 150 ℃. The CuO/ZnO sensor showed the maximum response to H₂S compared with other interfering gases such as ethanol, methanol, and CO, indicating its high selectivity.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.297-299
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• 1999

Effects of additives on the ceramic and electrical properties of Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$ceramics in a perovskite type structure were investigated. The dielectric and piezoelectric properties of the base composition were improved markedly through selection of Fe$_2$O$_3$ additives in proper amounts. The composition Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$ obtained the dielectric constant ($\varepsilon$$_{r}$=1,425). Also, electromechanical couping factors for planar(k$_{p}$) and piezoelectric constant(d$_{33}$) were obtained 0.50 and 294[pC/N] at the additives 0wt% Fe$_2$O$_3$ respectively. The mechanical quality facor(Q$_{m}$) of Pb(Y$_{1}$2/Ta$_{1}$2/)O$_3$-PbZrO$_3$-PbTiO$_3$+Fe$_2$O$_3$(0.3 wt%) is about 510.510.510.

• 한국표면공학회지
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• 제47권4호
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• pp.210-214
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• 2014

We investigated emission characteristics of tandem organic light emitting devices (OLEDs) with p-type materials as charge generation layer. The tandem OLEDs were fabricated by using $MoO_x$, $WO_x$, C60 and HATCN as p-type material or not using p-type material for charge generation. When HATCN was used as p-type material, it showed high current density at low applied voltage, but increase of efficiency was small because of charge unbalance in emitting layer. In case of tandem OLED not using p-type material, applied voltage increased remarkably because of difficulty of hole injection. In case of $MoO_x$, $WO_x$ or C60 as p-type material, current emission efficiency increased greatly. In particular, current emission efficiency of tandem OLED using $MoO_x$ as p-type material increased up to 3 times than current emission efficiency of single OLED. The Commission Internationale de l'Eclairage (CIE) 1931 color coordinates were changed by overlapping of 504 nm emission wavelength. As a result, emission efficiency of tandem OLED improved compared with single OLED, but driving voltage also increased by increase of organic layer thickness.

• Journal of Ceramic Processing Research
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• 제13권spc2호
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• pp.336-340
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• 2012

Wide band gap p-type hydrogenated amorphous silicon oxide (a-SiO:H) buffer layer has been used at the interface of transparent conductive oxide (TCO) and hydrogenated amorphous silicon (a-Si:H) p-type layer of a p-i-n type a-Si:H solar cell. Introduction of 5 nm thick buffer layer improves in blue response of the cell along with 0.5% enhancement of photovoltaic conversion efficiency (η). The cells with buffer layer show higher open circuit voltage (Voc), fill factor (FF), short circuit current density (Jsc) and improved blue response with respect to the cell without buffer layer.

• 한국수정란이식학회지
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• 제30권1호
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• pp.23-31
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• 2015

Catalpol, an iridoid glucoside, isolated from the root of Rehmannia glutinosa Libosch. It possesses a broad range of biological and pharmacological activity including anti-tumor, anti-inflammation and anti-oxidant by acting as a free radical scavenger. Therefore, in this study, the effects of catalpol on blastocyst development, expression levels of reactive oxygen species (ROS) and apoptotic index were investigated in porcine embryos. After in vitro maturation and fertilization, porcine embryos were cultured for 6 days in porcine zygote medium 3 (PZM-3) supplemented with catalpol (0, 100, 200 and $400{\mu}M$, respectively). Blastocyst development not significantly improved in the catalpol treated group when compared with control group. Otherwise, the intracelluar levels of ROS were decreased and the numbers of apoptotic nuclei were reduced in the catalpol ($100{\mu}M$) treated porcine blastocysts (P<0.05). On the other hand, blastocyst development was significantly improved in the catalpol ($100{\mu}M$) treated group when compared with the untreated catalpol group under $H_2O_2$ ($200{\mu}M$) induced oxidative stress (P<0.05). Otherwise, the intracellular levels of ROS in catalpol ($100{\mu}M$) treated group were significantly decreased in the untreated catalpol group under $H_2O_2$ ($200{\mu}M$) induced oxidative stress (P<0.05). Furthermore, the total cell numbers of blastocysts were significantly increased (P<0.05) in the catalpol ($100{\mu}M$) treated group under $H_2O_2$ ($200{\mu}M$) induced oxidative stress, whereas numbers of apoptoic nuclei were significantly reduced (P<0.05). In conclusion, our results indicate that treatment of catalpol may have important implications for improving developmental competence and preimplantation quality of porcine embryos through its anti-oxidant and anti-apoptotic effect.