• Applied Science and Convergence Technology
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• 제26권4호
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• pp.70-73
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• 2017

The dielectric constant and loss of poling/non-poling was measured in the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ samples. The addition of $La^{3+}$ to the $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ did not cause a large change in grain size. But the addition of $La^{3+}$ did show transition temperature, which shifted toward low temperature in the $Pb[(Mg_{1/3}Ta_{2/3})Zr]O_3$ systems. In addition, the dielectric and pyroelectric properties (${\varepsilon}{\sim}20000$, $p{\sim}0.03C/m^2K$) of this system using $La^{3+}$ have been greatly improved. Pyroelectrics $Pb_{0.97}La_{0.02}(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ system was found to have a relatively high ferroelectric FOMs ($F_V{\sim}0.035m^2/C$, $F_D{\sim}0.52{\times}10^{-4}Pa^{-1/2}$) at room temperature. Spontaneous polarization showed a value of $0.27{\sim}0.35C/m^2$ in the composition added to $La^{3+}$. The piezoelectric constant ($d_{33}=350{\sim}490pC/N$) and electromechanical coupling factor ($k_P=0.25{\sim}0.35$) are obtained in $Pb_{1-3x/2}La_x[(Mg_{1/3}Ta_{2/3})_{0.66}Zr_{0.34}]O_3$ compositions with $La^{3+}$ dopant.

• Corrosion Science and Technology
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• 제7권6호
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• pp.338-343
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• 2008

The electrochemical properties of W-modified austenitic stainless steels containing Ta and La were evaluated in a $H_{3}PO_{4}$ type PEMFC environment. Electrochemical test was conducted in 0.05 M $H_{3}PO_{4}$ solution at $80^{\circ}C$ and electrical property was conducted by contact resistance test. XPS was conducted to analyze the chemical elements consisting of passive film. Addition of La and Ta in W-modified austenitic stainless steel shows not only better corrosion resistance but also better electrical property.

• 한국세라믹학회지
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• 제54권4호
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• pp.278-284
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• 2017

In this work, Ta-substituted $Li_7La_3Zr_{2-x}O_{12}$ (LLZTO) powder and pellets with garnet cubic structure were fabricated and characterized by modified and optimized sol-gel synthesis. Ta-substituted LLZO powder with the smallest grain size and pure cubic structure with little pyrochlore phase was obtained by synthesis method in which Li and La sources in propanol solvent were mixed together with Zr and Ta sources in 2-methoxy ethanol. The LLZTO pellets made with the prepared powder showed cubic garnet structure for all conditions when the amount of Li addition was varied from 6.2 to 7.4 mol. All the X-ray peaks of the pyrochlore phase disappeared when the Li addition was increased above 7.0 mol. When the final sintering temperature was varied, the LLZTO pellet had a pyrochlore-mixed cubic phase above $1000^{\circ}C$. However, the surface morphology became much denser when the final sintering temperature was increased. The sol-gel-driven LLZTO pellet with a sintering temperature of $1100^{\circ}C$ showed a lithium ionic conductivity of 0.21 mS/cm when Au was adopted as electrode material for the blocking capacitor. The results of this study suggest that modified sol-gel synthesis is the optimum method to obtain cubic phase of LLZTO powder for highly dense and conductive solid electrolyte ceramics.

• 한국세라믹학회지
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• 제36권6호
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• pp.640-645
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• 1999

Recently rapid progress of electronic and telecommunication technology requires the development of new piezoelectric materials and cellular communication is more and more used in various fields. Langasite(La3Ga5SiO14) is suitable for new piezoelectric properties. Langastie can be applied as communication devices due to intermediate piezoelectric properties which are similar to those of quartz and LiTaO3 in its acoustic characteristics. So in this study Langastie(La3Ga5SiO14) single crystal with 47 mm in diameter and 25mm in length were sucessfully grown by using self-designed Czochralski system. In addition optimum growth conditions for the piezoelectric applications throughout estimation of crystal quality and frequency characteristics were investigated.

• 한국식품저장유통학회지
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• 제12권2호
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• pp.179-183
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• 2005

솔잎 열수 증류액에 대한 항산화 활성은 $RC_{50}$ 값이 $18.4\;{\mu}L$로서 매우 강한 항산화 활성을 나타내었다. 솔잎 열수 증류액에 대한 항돌연변이 활성은 S. typhimurium TA98과 TA100 균주를 이용한 돌연변이성 실험 결과 솔잎 열수 증류액 자체로서는 변이원성이 없었으며 항돌연변이원성 실험에서는 직접변이원인 WNNG $(0.4\;{\mu}L/plate)$의 경우 S. typhimurium TA100 균주에서 시료농도 $200\;{\mu}L/plate$에서 $45.9\%$의 억제활성을 나타내었으며 4NQO $(0.15\;{\mu}g/plate)$에 대해서는 동일 농도에서 $85.5\%$의 높은 억제활성을 나타내었다. 그리고 간접변이원인 $B(\alpha)P\;(10\;{\mu}g/plate)$에 대해서는 시료농도 $200\;{\mu}g/plate$의 시료농도에서 $88\%$의 높은 억제 활성을 나타내었다. 한편 Trp-P-1 $0.15\;{\mu}g/plate$에 대해서는 $50\;{\mu}g/plate$의 낮은 시료농도에서도 $85\%$의 높은 억제활성을 나타내었으며 모두 농도 의존적으로 억제하는 것으로 나타났다. 솔잎 열수 증류액의 암세포 성장억제효과를 검토한 결과, 폐암세포, 유방암세포에 대해서 각각 $78.7\%$, $62.3\%$의 비교적 높은 억제효과를 보였으며, 특히 위암세포, 자궁암세포, 간암세포에서 각각 $90.8\%,\;93.7\%,\;90.0\%$의 높은 억제효과를 나타내었다.

• 동아시아식생활학회지
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• 제17권4호
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• pp.563-570
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• 2007

This study was performed to observe the antioxidative effects, antimutagenic capacity, and cytotoxic activity of the 70% ethanol extract, and fractions, of Agaricus blazei Murill mycelium, using DPPH free radical scavenging ability, the Ames test, and SRB assay, respectively. Among the fractions, ethyl acetate showed the most effective antioxidative capacity according to the $RC_{50}$(73.6 $\mu$g/mL) of the scavenging effect on the DPPH radical. The inhibition rate of both the aqueous fraction and 70% ethanol extract(200 $\mu$g/plate) toward the Salmonella typhimurium TA100 strain was 94.6%, and it was 89.4% against the mutagenesis induced by MNNG(0.4 $\mu$g/plate). In addition, an identical concentration of the 70% ethanol extract in the TA98 strain, and the ethyl acetate fraction in the TA100 strain, showed inhibition rates of 80.3% and 76.9%, respectively, the highest activities against the mutagenesis induced by 4NQO(0.15 $\mu$g/plate). The cytotoxic effects of the 70% ethanol extract and its fractions increased with increasing sample concentration against human cervical adenocarcinoma(HeLa), human hepatocellular carcinoma(Hep3B), human breast adenocarcinoma(MCF-7), human stomach adenocarcinoma(AGS), and human lung carcinoma (A549). A 1 mg/mL concentration of the ethyl acetate fraction showed cytotoxicities of 77%, 83.8%, 82.1%, 83.1%, and 92.6% against HeLa, Hep3B, MCF-7, AGS and A549, respectively.

• 한국식품영양과학회지
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• 제36권2호
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• pp.143-148
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• 2007

메밀 함량이 높은 국수 개발 및 메밀 원료에서부터 제품에 이르기까지의 영양적 가치와 기능성에 대한 과학적 연구를 위해서 메밀가루 및 메밀가루 혼합분에 대해서 반죽 특성과 생리활성을 조사하였다. 아밀로그래프 및 파리노그래프를 사용한 리올로지특성은 호화온도와 최고 점도는 B1에 비하여 메밀 혼합분에서는 낮아졌고, 파리노그래프 측정 결과 B1이 $BF1\simBF4$에 비하여 수분 흡수율은 낮게 나타났으며 반죽형성시간은 BF2에서 9.2분으로 가장 길었다. 메밀 혼합분 에탄올 추출물의 MNNG$(0.4{\mu}g/plate)$에 대한 항돌연변이 효과에서 S. Typhimurium TA100 균주에 대해 B1, BF4 및 BF3의 추출물은 시료농도 160 g/plate에서 각각 45%, 42% 및 37.3%의 돌연변이 억제효과를 나타내었다. 동일 시료 농도에서 4NQO(0.15 g/plate)에 대해서는 S. Typhimurium TA98과 TA100 균주에서 B1 추출물의 시료농도가 $160{\mu}g/plate$일 때 각각 64%와 44.3%의 가장 높은 억제활성을 나타내었다. 그리고 유방암세포에 대한 암세포 성장 억제활성을 검토한 결과, B1, BF4 및 BF3 추출물의 시료 농도 1 mg/mL에서 67.9%, 63% 및 59%의 억제효과를 나타내었다. 동일시료 농도에서 간암세포의 경우 B1에서 72.6%, 위암세포의 경우 모든 시료에서 70% 이상의 암세포 성장 억제효과를 나타내었으며, 특히 BF3의 경우 81.1%의 높은 억제효과를 보였다. 폐암세포와 자궁암세포에서는 60% 이상의 암세포 성장억제 효과를 나타내었다.

• 신재생에너지
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• 제20권2호
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• pp.71-81
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• 2024

In this study, the electrochemical properties of garnet-structured all-solid-state battery electrolytes (Li_6.4La₃Zr_1.4Ta_0.6O₁₂, hereafter LLZTO) were assessed by altering the calcination temperature, while maintaining a consistent sintering duration. Among the various heat treatment conditions employed for sample fabrication, the '700_1100' condition, denoting a calcination temperature of 700℃ and a sintering temperature of 1100℃, resulted in the most exceptional ionic conductivity of 4.89 × 10^-4 S/cm and a relative density of 88.72% for the LLZTO material. This is attributed to the low calcination temperature of 700℃, leading to reduced grain size and enhanced cohesiveness, thus resulting in a higher sintered density. In addition, a microstructure similar to the typical sintering characteristics observed in Spark Plasma Sintering (SPS) methods was identified in the SEM analysis results under the '700_1100' condition. Consequently, the '700_1100' heat treatment condition was deemed to optimal choice for enhancing ionic conductivity.

• 한국식품영양과학회지
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• 제44권4호
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• pp.516-523
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• 2015

도라지 추출물과 그것의 분획물들(헥산, 클로로포름, 에틸아세테이트, 부탄올 및 물)의 발암물질 N-nitrosodimethylamine(NDMA)과 유전독성에 대항하는 안전성, 항돌연변이 및 항암 효과를 연구하였다. 도라지 추출물과 그것의 분획물들의 유전독성학적 안전성 평가를 위한 복귀돌연변이 시험은 S. Typhimurium TA98과 TA100의 복귀변이 집락수를 조사하는 Ames test로 수행하였다. 도라지 추출물과 그것의 분획물들은 복귀변이 집락수를 유의적으로 변화시키지 않았고, N-methyl-N'-nitro-N-nitroso-guanidine과 4-nitroquinoline 1-oxide에 의해 유발된 돌연변이에 대해 농도 의존적으로 돌연변이 억제 효과가 있었다. 도라지 추출물과 그것의 분획물들 중에 에틸아세테이트 분획물이 가장 높은 항돌연변이 효과를 나타내었다. 도라지 70% 에탄올 추출물 및 분획물들은 인간 자궁경부암세포(HeLa), 인간 간암세포(HepG2), 인간 유방암세포(MCF-7) 및 인간 폐암세포(A549) 성장 억제 효과를 나타내었고, 인간 신장정상세포(293)는 암세포보다 억제 효과가 낮았다. 더하여 in vivo에서 도라지 70% 에탄올 추출물 및 분획물의 항암 효과를 검토하기 위하여 Balb/c 마우스에 sarcoma-180 종양세포로 고형암을 유발시키면서 도라지 추출물과 그것의 분획물들의 고형암 성장 억제 효과를 알아본 결과 농도 의존적으로 고형암 성장 억제 효과를 나타냈고 도라지 에틸아세테이트 분획물이 가장 높은 억제 효과를 보였다. 그리고 도라지 에틸아세테이트 분획물은 NDMA 생성을 억제하였다. 따라서 도라지 에틸아세테이트 분획물은 항돌연변이 및 항암 효과가 있었고 현재 실험 조건에서 안전한 새로운 항암 소재 후보라는 것을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
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• pp.174-174
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• 2008

Non-volatile memories using ferroelectric-gate field-effect transistors (Fe-FETs) with a metal/ferroelectric/semiconductor gate stack (MFS-FETs) make non-destructive read operation possible. In addition, they also have features such as high switching speed, non-volatility, radiation tolerance, and high density. However, the interface reaction between ferroelectric materials and Si substrates, i.e. generation of mobile ions and short retention, make it difficult to obtain a good ferroelectric/Si interface in an MFS-FET's gate. To overcome these difficulties, Fe-FETs with a metal/ferroelectric/insulator/semiconductor gate stack (MFIS-FETs) have been proposed, where insulator as a buffer layer is inserted between ferroelectric materials and Si substrates. We prepared $SrBi_2Ta_2O_9$ (SBT) film as a ferroelectric layer and $LaZrO_x$ (LZO) film as a buffer layer on p-type (100) silicon wafer for making the MFIS-FET devices. For definition of source and drain region, phosphosilicate glass (PSG) thin film was used as a doping source of phosphorus (P). Ultimately, the n-channel ferroelectric-gate FET using the SBT/LZO/Si Structure is fabricated. To examine the ferroelectric effect of the fabricated Fe-FETs, drain current ($I_d$) versus gate voltage ($V_g$) characteristics in logarithmic scale was measured. Also, drain current ($I_d$) versus drain voltage ($V_d$) characteristics of the fabricated SBT/LZO/Si MFIS-FETs was measured according to the gate voltage variation.