• 한국전기전자재료학회논문지
• /
• 제25권5호
• /
• pp.381-386
• /
• 2012

To study encapsulation method for large-area organic light emitting diodes (OLEDs), red emitting OLEDs were fabricated, on which $Alq_3$ as organic buffer layer and LiF and Al as inorganic protective layers were deposited to protect the damage of OLED by epoxy. And then the OLEDs were attached to flat glass by printing method using epoxy. The basic structure of OLED doped with rubrene of 1 vol.% as emitting layer is ITO(150 nm) / 2-TNATA(50 nm) / ${\alpha}$-NPD(30 nm) / $Alq_3$:Rubrene(30 nm) / $Alq_3$(30 nm) / LiF(0.7 nm) / Al(100 nm). In case of depositing $Alq_3$, LiF and Al and then attaching of flat glass onto OLED, current density, luminance, efficiency and driving voltage were not changed and lifetime was increased according to thickness of Al as inorganic protective layers. The lifetime of OLED/$Alq_3$/LiF/Al_4/glass structure was 139 hours increased by 15.8 times more than bare OLED of 8.8 hours and 1.6 times more than edge sealed OLED of 54.5 hours.

• 한국광물학회지
• /
• 제2권1호
• /
• pp.8-10
• /
• 1989

Sphene from the McDonald pegmatite near Bancroft, Ontario, Canada was analyzed using EPMA. It contains 4.3 to 6.3 weight percent of Nb2O5 with an average formula Ca1.02(Ti0.62Al0.22Nb0.07Fe0.06Ta0.01)Si0.99(O4.85F0.16). Three types of subtitutions are possible; 1)2Ti4+=(Nb, Ta)5+ + (Al, Fe3+), 2) Ti + O = (Al, Fe3+) + (F, OH), and 3) 2Ti + O = Fe2+ + (Nb, Ta)5+ + (F, OH). T재 different schemes of substitutions for balancing the analysis are considered when the iron is either all ferric or all ferrous. Assuming stoichiometry fo Ca and Si, a general formula derived from the two different schemes is Ca(Ti0.64Al0.22Fe3+0.06-X {{{{Fe_{x}^{2+} }} Nb0.01)Sio4.80-XF0.16(OH)0.04+x.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 하계학술대회 논문집
• /
• pp.312-312
• /
• 2009

본 연구에서는 Thermal evaporator(저항 가열 식 진공 증착법) 장비를 활용하여 ZnS/$Na_3AlF_6$/ZnS/Cu-$0.25\lambda$, ZnS/$CaF_2$/ZnS/Cu-$0.25\lambda$의 다층 박막을 glass 기판위에 증착하였다. 증착 전에 EMP(Essential Macleod Program)을 활용하여 광학적 특성을 simulation하였으며 다층 박막 제작 후 Spectrophotometer를 사용하여 반사율 및 색상을 CIE $L^*a^*b^*$ 좌표에 표시하여 고 굴절 물질에 따른 광학적 특성을 EMP simulation과 비교하였다. AES depth profile을 분석하여 막의 두께 및 층간 확산여부에 관하여 관측 하였다. 저굴절 물질을 Na3AlF6로 사용하였을 경우 simulation과 결과 값 모en purple 계통의 색상을 나타냈으며 CaF2를 사용하였을 경우 simulation은 purple 계통의 색상, 결과값은 red-yellow 계통의 색상으로 나타났다.

• 대한수학회지
• /
• 제51권3호
• /
• pp.495-507
• /
• 2014

Nielsen and Rege-Chhawchharia called a ring R right McCoy if given nonzero polynomials f(x), g(x) over R with f(x)g(x) = 0, there exists a nonzero element r ${\in}$ R with f(x)r = 0. Hong et al. called a ring R strongly right McCoy if given nonzero polynomials f(x), g(x) over R with f(x)g(x) = 0, f(x)r = 0 for some nonzero r in the right ideal of R generated by the coefficients of g(x). Subsequently, Kim et al. observed similar conditions on linear polynomials by finding nonzero r's in various kinds of one-sided ideals generated by coefficients. But almost all results obtained by Kim et al. are concerned with the case of products of linear polynomials. In this paper we examine the nonzero annihilators in the products of general polynomials.

• 한국세라믹학회지
• /
• 제17권2호
• /
• pp.61-68
• /
• 1980

The effect of the addition of various fluoreides on the mullitization of Korean crude kaolin was studied by X-ray powder diffraction and scanning electron microscopic methods. Kaolin without any addition of fluoreides began to be transformed into the mullite at 1, 10$0^{\circ}C$. Mullite peaks were discernible in the X-ray diffraction patterns of the specimens which contained fluorides equivalent to about 2 wt % fluorine, and which were sintered at 1, 05$0^{\circ}C$. The higher the concentration of fluorine in kaolin, the lower was the initiatinig temperature of mullitization. Experiments , for example, showed that mullite could be formed at 95$0^{\circ}C$ from kaolin mixed with 3.4% fluorine. Of the fluoride, addtives, sodiumsiliconfluoride $(Na_2SiF_6)$ was must effective in mullite formation of kaolin. In order of accelerating mullitization, the fluorides except $Na_2SiF_6$ could be placed in following sequence ; (1) sodium (NaF) (2) aluminium$(AlF_3)$ (3)potassium(KF) (4) ammonium$(NH_4F)$ (5) magnesium$(MgF_2)$ (6) calcium$(CaF_2)$. It was considered that the intrinsic characteristics of fluorides, such as size of ionic radiu, charge , bond strength between cation and anion, and electronegativity of cation affected millitization of halloysite, a main constituent mineral of kaolin.

• Korean Chemical Engineering Research
• /
• 제58권1호
• /
• pp.52-58
• /
• 2020

본 연구에서는 MgF₂를 이용하여 LiNi_0.8Co_0.15Al_0.05O₂ 양극활물질의 표면을 코팅하여 전기화학적 특성과 열적 안정성을 평가하였다. 코팅된 MgF₂의 비율은 0.5, 1, 3 wt%로 조절하였다. 전기화학적 특성은 CV, 충·방전 프로파일, 출력특성, 수명특성을 분석하였고, 열적 안정성은 DSC 분석을 통하여 이루어졌다. 전기화학적 특성 분석 결과 0.1C에서 초기 방전 용량은 MgF₂ 코팅이 되었을 때 감소하였지만, 2C까지 출력을 향상 시켰을 때는 약간 향상된 방전 용량을 얻을 수 있었고, 수명특성 또한 향상되었다. 또한 DSC 분석 결과 코팅이 되었을 때 발열 온도가 증가하였고, 발열 피크의 세기 또한 감소하였다.

• Nuclear Engineering and Technology
• /
• 제55권12호
• /
• pp.4642-4646
• /
• 2023

The Tb³⁺ or Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor were fabricated by funace at 1500 ℃ for 12 h using a solid state reaction. The XRD (X-ray diffraction_Panalytical X'Pert Pro) and FE-SEM (field emission scanning electron microscope) are measured to confirm the crystalline structure and surface morphology of the phosphor. The Tb³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor emits the lights in 470~650 nm wavelength range due to transitions from ⁵D₄ to ⁷F_j. Therefore, it shows the green region in the CIE chromaticity diagram under both UV and X-rays excitations. The Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor emits the lights in 550~750 nm wavelength range because of ⁵D_i to ⁷F_j. The emission is confirmed to be in the red region using the CIE chromaticity diagram. The Tb³⁺ or Eu³⁺-doped Lu₂Gd₁Ga₂Al₃O₁₂ phosphor shows the characteristic f-f transition with a long decay time, which is about several milliseconds. They have the high efficiency of light emission for X-ray because of their high effective Z number (Z_eff = 58.5) and density. Therefore, they are very much promising phosphors for X-ray imaging application in medical fields.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1996년도 하계학술대회 논문집 C
• /
• pp.1466-1468
• /
• 1996

The standards of the capacitance arc measured and analyzed by the dry nitrogen or mica film as a dielectric. In this paper, respectively the standard capacitors of 10 pF and 100 pF for the establishment of the dielectric loss tangent are made by $Al_{2}O_{3}$ crystal disc with the low dielectric loss tangent, and then measured the dielectric loss tangent with precision. To regard for the existence of capacitances just in the dielectric, 3-terminal configuration electrode is used. With using the 2D electric field simulator, precise design values are derived in addition to stray capacitance. As stated above method, respectively the standards of the capacitances with 10 pF and 100 pF arc made with the low dielectric loss tangent less than $10^{-4}$.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
• /
• pp.653-656
• /
• 1999

Effect of $Al_2O_3$ Additives on Microwave Dielectric Properties of $0.15(Ba_{0.85}Ca_{(0.15-y)}Mg_y)$-0.125 $Nd_2O_3-0.60TiO_2+10wt%Bi_zO_3$ (y=0.05, 0.08) Ceramics was investigated. To control of $\tau\;{f}$ on microwave dielectric properties of $0.15(Ba_{0.85}Ca_{(0.15-y)}Mg_y)$-0.125 $Nd_2O_3-0.60TiO_2+10wt%Bi_zO_3$ ceramics $Al_2O_3$ was doped in the composition range of 0 to 0.15 wt%. As a result, dielectric constant was decreased from 94 to 80 but $Q\cdot{f}_0$ value was increased from 4980 to 5210 GHz and temperature coefficient of resonant frequency can be controlled from +9 to -10$ppm^\circ{C}$ as an increase of$Al_2O_3$ doping concentration. Especially, a new microwave dielectric material having $\varepsilon\;_r=84,\;Q\cdot{f}_0=5120\;GHz\;and\;\tau_f=0\;ppm/^\circ{C}$ was obtained at $Al_2O_3$ doping concentration of 0.08 wt%.

• 한국세라믹학회지
• /
• 제54권4호
• /
• pp.340-348
• /
• 2017

$SiC_f/SiC$ composites were joined using a $60{\mu}m-thick$ $Ti_3AlC_2$ or $Ti_3SiC_2$ MAX phase tape. The filler tape was inserted between the $SiC_f/SiC$ composites containing a 12 wt.% $Al_2O_3-Y_2O_3$ sintering additive. The joining was performed to a butt-joint configuration at $1600^{\circ}C$ or $1750^{\circ}C$ in an Ar atmosphere by applying 3.5 MPa using a hot press. Microstructural and phase analyses at the joining interface confirmed the decomposition of $Ti_3AlC_2$ and $Ti_3SiC_2$, indicating the joining by solid-state diffusion. The results showed sound joining interface without the presence of cracks. Joining strengths higher than 150 MPa could be obtained for the joints using $Ti_3AlC_2$ or $Ti_3SiC_2$ at $1750^{\circ}C$, while those for joined at $1600^{\circ}C$ decreased to 100 MPa approximately without the deformation of the joining bodies. The thickness of initial filler tape was reduced significantly after joining because of the decomposition and migration of MAX phase owing to the plasticity at high temperatures.