• 한국전기전자재료학회논문지
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• 제17권5호
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• pp.492-496
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• 2004

In this study, (0.96 －x)(PSN-PZT)－xBF－0.04 PNW＋0.3wt%MnO$_2$＋0.6wt%CuO ceramics were fabricated with the variations of the amount of BiFeO$_3$substitution and sintering temperature for the development of modified ceramics which can be sintered in the low temperature($\leq$100$0^{\circ}C$ ), and their microstructural, dielectric and piezoelectric characteristics were investigated. As the amount of BiFeO$_3$ substitution was increased, the density, mechanical quality factor(Q$_{m}$) and electromechanical coupling factor(k$_{p}$) showed the maximum value at each of sintering temperature. At sintering temperature of 98$0^{\circ}C$ and BiFeO$_3$substitution of 2 mol%, the density, dielectric constant and electromechanical coupling factor(k$_{p}$) showed the maximum value of 7.84 g/㎤, 1415 and 0.49, respectively. And at sintering temperature of 95$0^{\circ}C$ and BiFeO$_3$substitution of 3mol%, mechanical quality factor showed the maximum value of 1062. 1062.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.300-303
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• 2003

[ $0.91(PSN-PZT)-0.05BF-0.04PNW+0.3wt%MnO_2+0.6wt%CuO+xwt%CeO_2$ ] ceramics were fabricated with the variations of $CeO_2$ addition at the sintering temperature of $950^{\circ}C$ and their microstructure and dielectric and piezoelectric characteristics were investigated. As the amount of $CeO_2$ addition increased, the grain size, density and electromechanical coupling factor(kp) were increased and the mechanical quality factor(Qm) was decreased. At the $0.3wt%CeO_2$, density, grain size and electromechanical factor(kp) showed the maximum value of $7.87g/cm^3$, $3.22{\mu}m$ and 0.5, respectively. However, mechanical quality factor(Qm) showed the minimum value of 807 at the $0.5wt%CeO_2$.

• 한국정보통신학회논문지
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• 제19권10호
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• pp.2269-2274
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• 2015

본 논문은 S 형태의 folded 커플링(coupling) 구조를 이용하여 세로 측의 크기를 줄인 λg/4 단락형 협대역 스터브(stub) 대역통과 여파기에 대해 제안을 한다. 제안된 여파기는 스터브의 구현을 위해 스터브의 임피던스 값 변화 없이 스터브의 위치를 변화시켜, 그에 따른 Qe(External Quality Factor) 값을 이용하여 협대역 대역통과 여파기를 구현 한다. 또한 협대역 대역통과 여파기의 전송선로 부분에 S 형태의 커플링(coupling) 구조를 집적시켜, 여파기의 가로 측 크기를 줄이도록 한다. 제안된 여파기의 중심 주파수는 5.8GHz, 대역폭은 3.4 % 이며, 삽입손실 및 반사손실은 각각 1.46 dB 및 16.5 dB의 측정결과를 얻었다.

• 한국전기전자재료학회논문지
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• 제19권9호
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• pp.838-842
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• 2006

0.03Pb$(Sb_{0.5}Nb_{0.5})O_{3}-0.03Pb(Mn{1/3}Nb{2/3)O_{3}-(0.94-x)PbTiO_{3}-xPbZrO_{3}$ ceramics doped with $CeO_{2}$ were synthesized by conventional bulk ceramic processing technique. Phases analysis, microstructures and piezoelectric properties were investigated as a function of $CeO_{2}$ content (0.03, 0.05, 0.1 0.3, 0.5 and 0.7 wt%). Microstructures and phases information were characterized using a scanning electron microscope (SEM) and an X-ray diffractometer (XRD). Mechanical quality factor ($Q_{m}$) and coupling factor(kp) were obtained from the resonance measurement method. Both $Q_{m}$ and $k_{p}$ were shown to reach to the maximum at 0.1 wt% $CeO_{2}$. In order to evaluate the stability of resonance frequency and effective electromechanical coupling factor ($K_{eff}$) as a function of $CeO_{2}$, the variation of resonance and anti-resonance frequency were also measured using a high voltage frequency response analyzer under various alternating electric fields from 10 V/mm to 80 V/mm. It was shown that the stability of resonance frequency and effective electromechanical coupling factor were increased with increasing the $CeO_{2}$ contents.

• 한국전기전자재료학회논문지
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• 제15권9호
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• pp.794-797
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• 2002

Piezoelectric properties of PZT-PSN ceramics were investigated as a function of WO$_3$ addition from 0 wt% to 6.0 wt%. The dielectric and piezoelectric characteristics of PZT-PSN ceramics have been investigated at different calcination (80$0^{\circ}C$~90$0^{\circ}C$) and sintering (110$0^{\circ}C$~130$0^{\circ}C$) temperatures. The grain size was increased with the addition of WO$_3$and the sintering temperatures. Anisotropic properties of electromechanical coupling coefficient and piezoelectric coefficient are proven to be dependent on processing temperatures and amount of addition. At the specimen with 0.6 wt% WO$_3$ addition, using calcination temperature of 80$0^{\circ}C$ and sintering temperature of 110$0^{\circ}C$ , mechanical quality factor(Q$_{m}$) and electromechanical coupling coefficient(k$_{p}$) showed the excellent results of 1560 and 0.48, respectively Experimental results indicated that the PZT-PSN system ceramics with WO$_3$impurity could be effectively used for the microtransformer and actuator applications, etc.etc.

• Animal cells and systems
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• 제2권1호
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• pp.1-8
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• 1998

Hepatocyte growth factor (HGF), originally discovered and cloned as a powerful mitogen for hepatocytes, is a four kringle-containing growth factor which specifically binds to membrane-spanning tyrosine kinase, c-Met/HGF receptor. HGF has mitogenic, motogenic (enhancement of cell movement), morphogenic (e.g., induction of branching tubulogenesis), and anti-apoptotic activities for a wide variety of cells. During embryogenesis, HGF supports organogenesis and morphogenesis of various tissues, including liver, kidney, lung, gut, mammary gland, and tooth. In adult tissues HGF elicits an organotrophic function which supports regeneration of organs such as liver, kidney, lung, and vascular tissues. HGF is also a novel member of neurotrophic factor in nervous systems. Together with the preferential expression of HGF in mesenchymal or stromal cells, and c-Met/HGF receptor In epithelial or endothelial cells, the HGF-Met coupling seems to orchestrate dynamic morphogenic processes through epithelial-mesenchymal (or-stromal) interactions for organogenesis and organ regeneration. HGF or HGF gene may well become unique therapeutic tools for treatment of patients with various organ failure, through its actions to reconstruct organized tissue architectures. This review focuses on recently characterized biological and physiological functions integrated by HGF-Met coupling during organogenesis and organ regeneration.

• 한국전기전자재료학회논문지
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• 제20권9호
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• pp.771-775
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• 2007

In this study, in order to develop low temperature sintering ceramics for thickness vibration mode multilayer piezoelectric transformer, $PbTiO_3$ system ceramics were fabricated using $Na_2CO_3,\;Li_2CO_3,\;MnO_2\;and\;Bi_2O_3$ as sintering aids and their dielectric and piezoeletric properties were investigated according to the amount of $Bi_2O_3$ addition. At the sintering temperature of $900^{\circ}C\;and\;Bi_2O_3$ addition of 0.1 wt%, density, grain size, thickness vibration mode eletromechanical coupling factor($k_t$), thickness vibration mode mechanical quality factor($Q_{mt}$) and dielecteic constant(${\varepsilon}_r$) showed the optimum value of $6.94g/cm^3,\;2.413{\mu}m$, 0.497, 3,162 and 209, respectively, for thickness vibration mode multilayer piezoelectric transformer application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.214-216
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• 2006

In this study, in order to develop the composition ceramics for low loss and low temperature sintering multilayer piezoelectric actuator, PMN-PZN-PZT ceramics were fabricated using two stage calcination method and $Li_2CO_3$, $Bi_2O_3$ and CuO as sintering aids and their piezoelectric characteristics were investigated according to the 2nd calcination and sintering temperature. At the calcination temperature of $750^{\circ}C$ and sintering temperature of $930^{\circ}C$, density, electromechanical coupling factor ($k_p$), mechanical quality factor ($Q_m$), Dielectric constant (${\varepsilon}_r$) and piezoelectric constant ($d_{33}$) of specimen showed the optimum value of $7.94g/cm^2$ 0.581, 1554, 1555 and 356pC/N, respectively for multilayer piezoelectric actuator application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 춘계학술대회 논문집 반도체 재료 센서 박막재료 전자세라믹스
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• pp.145-149
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• 2004

In this study, leed-free piezoelectric ceramics were investigated for pressure sensor applications as a function of the amount of $La_2O_3$ addition at BNKT system. With increasing amount of $La_2O_3$ addition, density and dielectric constant were increased up to 0.9wt% addition and decreased after 0.9wt% addition, electromechanical coupling factor$(k_p)$ and mechanical quality factor$(Q_m)$ showed the maximum values at 0.2wt% addition and decreased after 0.2wt% addition. The $k_p$, density, dielectric constant and $Q_m$ were showed the optimum values of 0.40, $5.71g/cm^3$, 768 and 118 at $La_2O_3$ 0.2wt% addition, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.181-182
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• 2005

In this study, in order to develop multilayer piezoelectric transformer, PMN-PZT ceramics were fabricated according to PFW substitution using $Li_2CO_3-CaCO_3$ as sintering aids and their dielectric and piezoelectric characteristics were investigated. As increasing the amount of PFW substitution, density was slightly increased due to the increased sinterability. At the 1[mol%] PFW substituted PMN-PZT ceramic sintered at 950[$^{\circ}C$], density, dielectric constant $\varepsilon_r$, electromechanical coupling factor kp, mechanical quality factor Qm and piezoelectric $d_{33}$ constant showed the optimum value of 7.761[$g/cm^3$], 1251, 0.479, 1425 and 282[pC/N], respectively.