• Transactions on Electrical and Electronic Materials
• /
• 제10권4호
• /
• pp.121-124
• /
• 2009

In this study, in order to develop compositions of ceramics suitable for piezoelectric actuator and ultrasonic vibrator applications using low temperature sintering, multilayer, PMN-PNN-PZT ceramics were fabricated using $Li_2CO_3$ and $Na_2CO_3$ as sintering aids. Their structural, piezoelectric and dielectric characteristics were investigated according to the Zr/Ti ratio. As the Zr/Ti ratio increased, the electromechanical coupling factor $k_p$, and piezoelectric constant $d_{33}$ and the mechanical quality factor $Q_m$ all increased with Zr/Ti ratio and then decreased after the ratio exceeded 50/50. At the ratio of Zr/Ti =49/51 and sintering temperature of $900^{\circ}C$; the density, electromechanical coupling factor $k_p$, dielectric constant ${\varepsilon}_r$ piezoelectric $d_{33}$ constant and mechanical quality factor $Q_m$ all showed the optimum values of 7.900 $g/cm^3$, 0.576, 856, 312 pC/N, 1,326, respectively. These property values are very suitable for multilayer ceramics actuator applications.

• 한국전기전자재료학회논문지
• /
• 제30권3호
• /
• pp.152-156
• /
• 2017

In this paper, $Pb(Mn_{1/3}Nb_{2/3})_{0.07}(Ni_{1/3}Nb_{2/3})_{0.10}(Zr_{0.5}Ti_{0.5})_{0.83}O_3$ ceramics were fabricated by the conventional solid state method to obtain excellent dielectric properties for ultrasonic generators. The effects of 2nd calcination temperature on their microstructure and piezoelectric properties were systematically investigated. The tetragonality increased in the ceramics when 2nd calcination temperature increased to the optimized temperature at $750^{\circ}C$. At that temperature, excellent physical properties ($d_{33}=352\;pC/N$, ${\varepsilon}_r=1,687$, $k_p=0.570$, $Q_m=1,640$) were obtained for ultrasonic generator application.

• 한국전기전자재료학회논문지
• /
• 제14권1호
• /
• pp.20-25
• /
• 2001

To develop the piezoelectric actuator, the structural, dielectric and piezoelectric properties and electric fieldinduced strain of the ceramics(Pb$\_$1-2/Ba$\_$x/)[Mg$\_$1/2/W$\_$1/2/)$\_$0.03/-Ni$\_$1/3/Nb$\_$2/3/)$\_$0.12/-(Zr$\_$0.5/Ti$\_$0.5/)$\_$0.85/]O$_3$(x=0, 0.01, 0.03, 0.05, 0.07, 0.1) were investigated with the substitution of Ba. The tetragonality of crystal structure and grain size decreased by the substitution of Ba. Curie temperature decreased due to the decrease of the tetragonality, and dielectric constants increased with the substitution of Ba. The coercive field, remnant polarization and electromechanical coupling factor also decreased, whereas the piezoelectric constatns d$\_$33/ and d$\_$31/ were showed the highest value of 430 and 209(x10$\^$-12/C/N), respectively, because of the increase of dielectric constant. The strain induced by 60Hz AC electric field had the maximum value of 204x10$\^$-6/Δℓ/ℓ at the substitution of Ba 3mol%. As the applied electric field approaches to the coercive field, the piezoelectric element is depolarized and the electric field induced strain revealed non-linearity.

• 복식
• /
• 제59권2호
• /
• pp.143-153
• /
• 2009

The purpose of this study is to provide color information in order to planning and merchandising in china fashion through the color of Beijing opera. In objective study, we collect total 302 Beijing opera images. The collecting method of source data is to extract digital color data by color picker. We transform RGB color data to H V/C, CIE L*a*b and analyze the attributes of color and tone, three-dimensional analysis. The results of this study are as follows : 1. The color distrbution of Beijing opera is R(26.9%)>YR(18.2%)>PB(11.6%)>Y(9.6%). Traditional preference color, red is most popular color as 26.7%:, the practice of vivid tone red is numerous. 2. The tone distribution of Beijing opera costume is P(16%)>It(13.9%)>d(11%)>5(9.6%)>4kg (8.2%)>b(7.1%:). The value o# Beijing opera costume distribute medium and medium-high and the chroma of those distributes low. 3. High chroma yellow is restrictive color as the symbol of emperor in china but medium-low chroma yellow is very frequently used. 4. Blue is often used in china costume. Especially in Beijing opera costume blue is symbol of bravery, dignity, cruel character 5. White in Beijing opera costume is much used for symbol of righteous loyalist. Black is less used than white in Beijing opera costume and black is authority color for symbol of the prime minister.

• 한국환경보건학회지
• /
• 제28권2호
• /
• pp.23-39
• /
• 2002

This study focuses on the structure of geographical conditions, the riverbed, the meterological and atmospheric examination, the ecological environment, the food chain and the ecosystem, in order to establish a basic plan for preparing a natural learning area of environmental ecosystem in Bukchun and its surroundings, Gyeongju. The results could be summarized as follows. Bukchun is a first grade which extends 6km along the road from Bomun bridge to the junction of Hyungsangang. The basin area is 7.10$\textrm{km}^2$ and the slope is 1/200~1/300. Gyeongju has good atmospheric conditions, i.e. SO$_2$0.011 ~0.017ppm, CO 0.8~ 1.5ppm, NO$_2$0.013~0.019ppm, $O_3$0.013~0.020ppm, TSP 85~142$\mu\textrm{g}$/㎥, PM-10 47~90$\mu\textrm{g}$/㎥ and Pb 0.057 ~0.129$\mu\textrm{g}$/㎥, which is below the annual and daily averages, and is little lower than those of Pohang and Ulsan. The ecosystem of Bukchun is based on the structure of the food chain, which includes birds such as the grey and white herons at the top of the food chain. This study also considers the development of the river's in terms of culture, environment and ecology concept.

• 한국식품영양과학회지
• /
• 제24권4호
• /
• pp.587-593
• /
• 1995

택사로부터 황산암모늄 분별 침전, DEAE-cellulose ion exchange chromatography, Sephadex G-150 chromatography 등의 방법을 이용하여 렉틴을 분리, 정제하였다. 정제한 렉틴의 분자량은 gel filtration법에 의해 측정한 결과 90,500 dalton이었으며, SDS polyacrylamide gel 전기영동을 실시한 결과 subunit 분자량은 각각 42,000, 27,000, 22,500 dalton으로 나타나므로 택사 렉틴이 heterotrimer임을 알았다. 정제된 택사 렉틴은 사람 적혈구의 경우 모든 혈액형에 대하여 응집현상을 나타내었으며 돼지, 쥐 및 개 등의 적혈구에 대해서도 모두 응집현상이 나타나 혈구 비특이성임을 보여주었다. 또한 이 렉틴은 sialic acid, glucose, ribose, sucrose, lactose, galactose 등 당에 의해서, 그리고 $Hg^{2+},\;Fe^{2+},\;Cu^{2+}$ 이온 등에 의해 적혈구 응집력이 저해되었다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
• /
• pp.469.2-469.2
• /
• 2014

All-solid-state solar cell based on Chloride doped organometallic halide perovskite, (CH3NH3)PbIxCl3-x, has achieved a highly power conversion efficiency (PCE) to over 15% [1] and further improvements are expected up to 20% [2]. In this way, solar cells using novel light absorbing perovskite material are actively being studied as a next generation solar cells. However, making solution-process require high temperature up to $500^{\circ}C$ to form compact hole blocking layer and sinter the mesoporous oxide scaffold layer. Because of this high temperature process, fabrication of flexible solar cells on plastic substrate is still troubleshooting. In this study, we fabricated highly efficient flexible perovskite solar cells with PCE in excess of 11%. Atomic layer deposition (ALD) is used to deposit dense $TiO_2$ as hole blocking layer on ITO/PEN substrate. The all fabrication process is done at low temperature below $150^{\circ}C$. This work shows that one of the important blueprint for commercial use of perovskite solar cells.

• 한국초전도저온공학회:학술대회논문집
• /
• 한국초전도저온공학회 2003년도 학술대회 논문집
• /
• pp.120-122
• /
• 2003

We jointed Bi(Pb)-Sr-Ca-Cu-O multifilament tapes and evaluated their electrical properties. In order to improve connectivity of multifilarnents, single-filament tape was inserted between two multifilament tapes or multifilament was stepped by mechanical remove. The critical current ratio (CCR) and n-value of the jointed tapes were evaluated as a function of uniaxial pressure. It was observed that CCR and n-value were 24.8-29.0% and 2.5-2.8 for lap-jointed tape. On the other hand, the corresponding values were improved to 51.8-61.9% and 2.9-5.1 for three stepped jointed tape, and 63.4-67.9% and 3.4-4.2 for double MSM lap-jointed tape, respectively. These improvements are to be due to better interconnection between filaments of two tapes.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
• /
• pp.59-61
• /
• 2005

In this paper, in order to develop the low temperature sintering ceramics for multilayer piezoelectric transformer, $Pb[(Mn_{1/3},Nb_{2/3})_{0.07}(Zn_{1/3}Nb_{2/3})_a(Zr_{0.48}Ti_{0.52})_{1-0.07-a}O_3]$ ceramics were manufactured with the variations of PZN from 2 to 14mol% and their dielectric and piezoelectric properties were investigated. Sintering temperature was varied from 910 to $1000^{\circ}C$. At 8mol% PZN substituted specimen sintered at $970^{\circ}C$, electromechanical coupling factor(kp), mechanical quality factor(Qm), dielectric constant and peizoelectric constant($d_{33}$) showed the optimal values of 0.536, 1803, 1551 and 328[pC/N), respectively, for multilayer piezoelectric transformer application.

• 한국재료학회지
• /
• 제30권7호
• /
• pp.343-349
• /
• 2020

NKN [(Na,K)NbO₃] is a candidate lead-free piezoelectric material to replace PZT [Pb(Zr,Ti)O₃]. A single crystal has excellent piezoelectric-properties and its properties are dependent of the crystal orientation direction. However, it is hard to fabricate a single crystal with stoichiometrically stable composition due to volatilization of sodium during the growth process. To solve this problem, a solid solution composition is designed (Na,K)NbO₃-Ba(Cu,Nb)O₃ and solid state grain growth is studied for a sizable single crystal. Ceramic powders of (Na,K)NbO₃-M(Cu,Nb)O₃ (M = Ca, Sr, Ba) are synthesized and grain growth behavior is investigated for different temperatures and times. Average normal grain sizes of individual specimens, which are heat-treated at 1,125 ℃ for 10 h, are 6.9, 2.8, and 1.6 ㎛ for M = Ca, Sr, and Ba, respectively. Depending on M, the distortion of NKN structure can be altered. XRD results show that (NKN-CaCuN: shrunken orthorhombic; NKN-SrCuN: orthorhombic; NKN-BaCuN: cubic). For the sample heat-treated at 1,125 ℃ for 10 h, the maximum grain sizes of individual specimens are measured as 40, 5, and 4,000 ㎛ for M = Ca, Sr, and Ba, respectively. This abnormal grain size is related to the partial melting temperature (NKN-CaCuN: 960 ℃; NKN-SrCuN: 971 ℃; NKN-BaCuN: 945 ℃).