• 공업화학
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• 제26권1호
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• pp.29-34
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• 2015

N,N'-diferuloyl-putrescine (DFP)은 회화나무 잎 등 식물계에 함유되어 있는 화합물로 피부 미백활성 및 항산화 활성 등이 있는 것으로 보고되고 있다. 본 연구에서는 식물계에서 미량 존재하는 DFP를 기능성 화장품 원료로 사용할 목적으로 다량 확보하고자 DFP 및 그 유도체(DFP-D)를 합성하였다. 합성한 DFP 및 DFP-D에 대한 항산화 활성을 DPPH법, 루미놀 발광법을 통하여 확인하였으며, 추가적으로 $^1O_2$에 대한 세포보호 효과를 평가하였다. 1,1-Diphenyl-2-picrylhydrazyl (DPPH) 라디칼 소거활성($FSC_{50}$)은 DFP가 $61.25{\pm}2.25{\mu}M$, DFP-D는 $12.92{\pm}0.72{\mu}M$을 나타냈으며, 루미놀 발광법을 이용한 $Fe^{3+}-EDTA/H_2O_2$계에 있어서의 총항산화능($OSC_{50}$)에서 DFP와 DFP-D는 비교물질로 사용한 L-ascorbic acid보다 각각 2배($1.84{\pm}0.12{\mu}M$) 및 13배($0.174{\pm}0.01{\mu}M$) 더 큰 총항산화능을 나타내었다. 피부 광노화에 있어서 핵심 역할을 하는 활성산소인 $^1O_2$으로 유도된 세포 손상에 있어서 $50{\mu}M$의 DFP-D의 세포 보호능(${\tau}_{50}=80.2min$)은 (+)-${\alpha}$-tocopherol (${\tau}50=43.6min$)보다 약 2배 정도 더 우수한 세포보호 효과를 나타내었다. 이상의 결과들을 통해 합성된 DFP 및 유도체 DFP-D의 강력한 항산화 활성은 기능성 화장품 원료로 사용하여 화장품 산업에 응용 가능성이 있음을 시사한다.

• 폴리머
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• 제32권3호
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• pp.219-229
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• 2008

A pH sensitive ternary copolymer gel was synthesized in the presence of ethylene glycol dimethacrylate (EGDMA) as a crosslinking agent through radical polymerization of vinyl acetate (VA), acrylic acid (AA) and methyl acrylate(MA) with a weight ratio of 1 : 1.3 : 1. A number of experiments were carried out to determine the swelling behavior of the gel under a variety of pH conditions of the swelling medium. As the pH of the swelling medium was changed from 1.0 to 8.0 at $37^{\circ}C$, the gel showed a shift in the pH-dependent swelling behavior from Fickian (n=0.3447) to non-Fickian (n=0.9125). The resulting swelling parameters were analyzed using graphical and statistical methods. The results showed that the swelling of the gel was controlled by the pH of the medium, i.e. $n=n_o{\exp}(S_{C}pH)$, where n is the diffusion exponent, $n_o(=28.9645{\times}10^{-2})$ is the pre-exponential factor and $S_C$(=0.1417) is pH sensitivity coefficient. The swelling behavior of the gel was also examined in aliphatic alcohols. The results showed that the rate of swelling increased with increasing number of carbon atoms in the alcoholic molecular chain.

• 반도체디스플레이기술학회지
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• 제9권4호
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• pp.77-81
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• 2010

The AZO thin films were deposited on the corning 1737 glass plate by the RF magnetron sputtering and effects of working pressure and oxygen contents on the electrical properties were investigated. XRD spectra showed a preferred orientation along the c-axis and a minimum FWHM for the 70mTorr. From the surface analysis (AFM), the number of crystal grain of AZO thin film increased as working pressure increased. The film deposited with 70mTorr of working pressure showed n-type semiconductor characteristic having suitable resistivity $-1.59{\times}10^{-2}{\Omega}cm$, carrier concentration $-10.1{\times}10^{19}cm^{-3}$, and mobility $-4.35cm^2V^{-1}s^{-1}$ while other films by 7 mTorr, 20 mTorr of working pressure closed to metallic films. The films including the oxygen represent stoichiometric composition similar to the oxide. The transmittance of the film was over 85% in the visible light range regardless of the changes in working pressure and oxygen contents.

• 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.

• 한국재료학회지
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• 제8권12호
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• pp.1146-1151
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• 1998

열처리 온도 및 시간의 변화에 따라 $PbO-TiO_2$-$A1_2O_3$-$SiO_2$유리계의 열처리된 시편들에서 perovskite $PbTiO_3$ 결정의 결정화 거동을 X선 회절 (XRD)과 주사 전자 현미경 (SEM)에 의하여 조사하였다 고온에서 장시간 동안 열처리된 시편은 높은 결정화도를 나타내었다. 열처리 시간이 증가할수록 $610^{\circ}C$와 $650^{\circ}C$ 에서 열처리된 시편들의 유전 상수는 증가했지만, $800^{\circ}C$에서 열처리된 시편의 유전 상수는 감소하였다. 시편들의 손실 정접은 열처리 조건에 거의 영향을 받지 않았다. $800^{\circ}C$에서 1h, 2h 및 8h 동안 열처리된 시편들의 압전 계수는 $1.0\times10^{-12}~8.0$\times$10^{-12}C/N$ 정도 이었다.

• Bulletin of the Korean Chemical Society
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• 제8권3호
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• pp.179-183
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• 1987

Reactions of $Rh(ClO_4)(CO)(AsPh_3)_2$ with unsaturated nitriles and aldehyde, L, produce a series of new cationic rhodium (I) complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ (L = $CH_2$ = CHCN, $CH_2$ = C($CH_3$)CN, trans-$CH_3CH$ = CHCN, $CH_2$ = CH$CH_2$CN, trans-$C_6H_5CH$ = CHCN, and trans-$C_6H_5CH$ = CHCHD) where L are coordinated through the nitrogen and oxygen, respectively but not through the ${\pi}$-system of the olefinic group. Dissociation constants for the reaction, $[RhL(CO)(AsPh_3)_2]ClO_4$ $\rightleftharpoons$ $Rh(ClO_4)(CO)(AsPh_3)_2$ + L, have been measured to be $1.20{\times}10^{-4}$ M (L = $CH_2$ = CHCN), $1.05{\times}10^{-4}$ M (L = $CH_2$ = C($CH_3$)CN, $3.26{\times}10^{-5}$ M (L = trans-$CH_3$CH = CHCN) and $6.45{\times}10^{-5}$ M (L = $CH_2$ = CH$CH_2$CN) in chlorobenzene at $25^{\circ}C, and higher than those of triphenylphosphine complexes, $[RhL(CO)(AsPh_3)_2]ClO_4$ where L are the corresponding nitriles that are coordinated through the nitrogen atom. The differences in dissociation constants seem to be predominantly due to the differences in ${\Delta}H$ (not due to the differences in ${\Delta}S$). The weaker Rh-N (unsaturated nitriles) bonding in $AsPh_3$ complexes than in $PPh_3$ complexes (based on ${\Delta}H$ values) suggests that the unsaturated nitriles in 2∼5 are good ${\sigma}$-donor and poor ${\pi}$-acceptor.

• 공업화학
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• 제22권4호
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• pp.376-383
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• 2011

글리시돌과 라우릴 알코올을 반응시켜 합성한 LA와 LA3 비이온계면활성제의 CMC는 각각 $0.97{\times}10^{-3}mol/L$, $1.02{\times}10^{-3}mol/L$이며, 1 wt% 농도에서의 표면장력은 26.99 mN/m과 27.48 mN/m이었다. 동적 표면장력 측정 결과에 의하면 LA와 LA3 비이온 계면활성제 모두, 공기와 수용액의 계면이 계면활성제 단분자에 의하여 비교적 짧은 시간 내에 포화되었으며, 1 wt% LA와 LA3 계면활성제 시스템들의 접촉각은 각각 27.8, $20.9^{\circ}$를 나타내었다. 비극성 오일 n-decane과 1 wt% 계면활성제 수용액 사이의 시간에 따른 계면장력은 시간에 따라 감소하며, LA와 LA3 시스템 모두 2~3 min 이내의 짧은 시간에 평형에 도달하였고, 평형에서의 계면장력 값은 각각 0.1524, 0.1716 mN/n을 나타내었다. $25^{\circ}C$에서의 계면활성제 수용액은 두 시스템 모두 비교적 안정한 상태를 유지하였고, LA 비이온 계면활성제가 LA3 비이온 계면활성제에 비하여 거품 안정성이 큼을 확인하였으며, 이러한 거품 안정성 측정 결과는 표면장력 측정 결과와도 일치하였다. 계면활성제, 물, 비극성 탄화수소 오일로 이루어진 3성분 시스템에 대하여 $25{\sim}60^{\circ}C$의 온도에서 상평형 실험을 수행한 결과, lower phase 마이크로에멀젼 혹은 oil in water (O/W) 마이크로에멀젼이 excess oil 상과 평형을 이루는 2상 영역만이 관찰되었을 뿐, lamellar liquid crystalline phase 혹은 middle-phase 마이크로에멀젼을 포함한 3상 영역은 나타나지 않았다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.255-255
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• 2010

Recently, nonvolatile memories (NVM) of various types have been researched to improve the electrical performance such as program/erase voltages, speed and retention times. Also, the charge trap memory is a strong candidate to realize the ultra dense 20-nm scale NVM. Furthermore, the high charge efficiency and the thermal stability of SiC nanocrystals NVM with single $SiO_2$ tunnel barrier have been reported. [1-2] In this study, the SiC charge trap NVM was fabricated and electrical properties were characterized. The 100-nm thick Poly-Si layer was deposited to confined source/drain region by using low-pressure chemical vapor deposition (LP-CVD). After etching and lithography process for fabricate the gate region, the $Si_3N_4/SiO_2/Si_3N_4$ (NON) and $SiO_2/Si_3N_4/SiO_2$ (ONO) barrier engineered tunnel layer were deposited by using LP-CVD. The equivalent oxide thickness of NON and ONO tunnel layer are 5.2 nm and 5.6 nm, respectively. By using ultra-high vacuum magnetron sputtering with base pressure 3x10-10 Torr, the 2-nm SiC and 20-nm $SiO_2$ were successively deposited on ONO and NON tunnel layers. Finally, after deposited 200-nm thick Al layer, the source, drain and gate areas were defined by using reactive-ion etching and photolithography. The lengths of squire gate are $2\;{\mu}m$, $5\;{\mu}m$ and $10\;{\mu}m$. The electrical properties of devices were measured by using a HP 4156A precision semiconductor parameter analyzer, E4980A LCR capacitor meter and an Agilent 81104A pulse pattern generator system. The electrical characteristics such as the memory effect, program/erase speeds, operation voltages, and retention time of SiC charge trap memory device with barrier engineered tunnel layer will be discussed.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.141-142
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• 2005

To investigate the ZnO thin films which is interested in the next generation of short wavelength LEDs and Lasers, our ZnO thin films were deposited by RF sputtering system. At sputtering process of ZnO thin films, substrate temperature, work pressure respectively is $300^{\circ}C$ and 5.2 mTorr, and the purity of target is ZnO 5N. The thickness of ZnO thin films was about $1.9{\mu}m$ at SEM analysis after sputtering process. Phosphorus (P) and arsenic (As) were diffused into ZnO thin films sputtered by RF magnetron sputtering system in ampoule tube which was below $5\times10^{-7}$ Torr. The dopant sources of phosphorus and arsenic were $Zn_3P_2$ and $ZnAs_2$. Those diffusion was perform at 500, 600, and $700^{\circ}C$ during 3hr. We find the condition of p-type ZnO whose diffusion condition is $700^{\circ}C$, 3hr. Our p-type ZnO thin film has not only very high carrier concentration of above $10^{19}/cm^3$ but also low resistivity of $5\times10^{-3}{\Omega}cm$.

• Nuclear Engineering and Technology
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• 제55권5호
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• pp.1734-1741
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• 2023

This work presents the synthesis and preparation of a new glass system described by the equation of (70-x) B₂O₃-5TeO₂ -20SrCO₃-5ZnO -xBi₂O₃, x = 0, 1, 5, 10, and 15 mol. %, using the melt quenching technique at a melting temperature of 1100 ℃. The photon-shielding characteristics mainly the linear attenuation coefficient (LAC) of the prepared glass samples were evaluated using Monte Carlo (MC) simulation N-particle transport code (MCNP-5) at gamma-ray energy extended from 59 keV to 1408 keV emitted by the radioisotopes Am-241, Ba-133, Cs-137, Co-60, Na-22, and Eu-152. Furthermore, we observed that the Bi₂O₃ content of the glasses had a significantly stronger impact on the LAC at 59 and 356 keV. The study of the lead equivalent thickness shows that the performance of fabricated glass sample with 15 mol.% of Bi₂O₃ is four times less than the performance of pure lead at low gamma photon energy while it is enhanced and became two times lower the perforce of pure lead at high energy. Therefore, the fabricated glasses special sample with 15 mol.% of Bi₂O₃ has good shielding properties in low, intermediate, and high energy intervals.