• 센서학회지
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• 제22권2호
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• pp.150-155
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• 2013

Recently, various hearing aids are developed to overcome hearing loss. There are available hearing aids, such as air conduction hearing aid, implantable middle ear hearing aid and so on. But air conduction hearing aid is inconvenience caused by howling, and ossicle chain driving type implantable middle ear hearing aid has some week point due to problem of possible nercobiosis of coupling spot along incus long process. In recent years, in order to improve these shortcomings round window (RW) driving hearing aid has been paying attention. In this paper, the physical cochlear model is proposed for a performance evaluation of the RW driving hearing aids of a transducer. In order to verify an experiment proposed on a performance of physical cochlear model, the transducer which has ossicles characteristics is used. By measuring and comparing the frequency characteristics of transducer with ossicles and human temporal bone, performance of physical cochlear model was verified. As from the result of experiment, it is expected that an implemented cochlear model is useful for evaluating characteristics of RW transducer.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.799-801
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• 1988

This paper was studied on the effects of Ca-La-Nb substitution and Zr/Ti ratio variation to Pb(Zr, Ti)$O_3$ system on structural, electrical, optical and sound level characteristics in order to develope the piezoelectric and electrooptic ceramic devices. Also the specimens were prepared by the two stage sintering technique. The molecular formular was X($CaO{\cdot}1/4La_{2}O_{3}{\cdot}1/4Nb_{2}O_{5}){\cdot}(1-X)Pb(Zr_{Y}Ti_{1-Y})O_{3}$(x=100X, y=100Y), and the variation of x was $6{\sim}12$, y was 60${\sim}$49 and second stage sintering time was 20${\sim}$40 hours. The experimental results obtained from this study are as follows : 1. The density was decreased, the grain size was increased according to increase of Ca-La-Nb substitution. 2. The crystal structure was rhombohedral in composition 6/60/40, and the crystal structure was tetragonal and cubic according to increase of Ca-La-Nb substitution. 3. The Ca substitution of PZT system enhanced the sintering property. The Pb site vacancy resulting from the substitution of La-Nb increased the dielectrical constant, the piezoelectric charge constant, the dielectric loss and decreased the coercive field. 4. The resistivity of PZT system which has the P type conduction mechanism increased according to substitution of La-Nb because of the substituent acting as donor. 5. The PZT ceramics varied from ferroelectric substance according to increase of Ca-La-Nb substituent. The coercive field and saturation remanent polarization decreased, and at last straight line according to increase of La-Nb substitution. 6. The amount of Ca-La-Nb substitution to improve the light transmittance of speciment was 10 mol%, the Zr/Ti ratio was 49/51, and the second stage sintering time was 40 hours. 7. According to Ca-La-Nb substitution, the specimens was to be transparent. The 7.5/51/49 specimen was suitable for transparent sound vibrator because it had 58% light transmittance (thick 0.2[mm], wave length 700[mm]) and 48% electromechanical coupling factor.

• 한국세라믹학회지
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• 제45권6호
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• pp.363-367
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• 2008

Lead-free $(K_{0.44}Na_{0.52})(Nb_{0.86}Ta_{0.10})-0.04LiSbO_3$ piezoelectric ceramics have been synthesized by conventional sintering process and then investigated on the sintering and piezoelectric properties by high energy ball milling (HEBM) treatment. The powders milled for different time are characterized by XRD, FE-SEM. The powders are pressed into a pellet and sintered. It is found that the piezoelectric properties of sintered specimens are strongly dependent on the milling time. The piezoelectric properties are enhanced by high energy ball milling treatment. The planer electromechanical coupling factor ($k_p$) and piezoelectric constant ($d_{33}$) of a specimen sintered at $1050^{\circ}C$ are 0.44 and 267 pC/N, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.317-321
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• 2002

Piezoelectric properties of $(Pb_{1-x}Y_x)[(Ni_{1/3}Nb_{2/3})_{0.15}(Zr_{1/2}Ti_{1/2)})_{0.85}]O_{3}$ (x=0~0.05) ceramics were investigated, The stoichiometric PNN-PZT ceramics required the sintering temperature above $1100^{\circ}C$, but the addition of $Y_{2}O_{3}$ in the PNN-PZT ceramic lowered the sintering temperature down to $1000^{\circ}C$. In case of x=0.005, the electro-mechanical coupling $factor(K_p)$, the piezoelectric $constant(d_{33})$, and the maximum strain ratio of PNN-PZT ceramics sintered at $1000^{\circ}C$ were 53.1%, 395pC/N, and $2200{\times}10^{-6}$ respectively, A 30-layer piezoelectric actuator$(10{\times}10{\times}1.7mm)$ fabricated with the above material showed the maximum strain of $2.09{\mu}m$ under 100V DC bias.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2002년도 추계학술대회 논문집 Vol.15
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• pp.334-337
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• 2002

In this study, the microstructure, dielectric and piezoelectric properties of $0.15Pb(Ni_{1/3}Nb_{2/3})O_3-0.85(PbZr_{0.5}Ti_{0.5})O_3$(0.15PNN-0.85PZT) ceramics having compositions near the morphotropic phase boundary(MPB) was investigated with respect to the variation of $Y_2O_3$ and $Ga_2O_3$ addition amount. The dielectric properties increased and piezoelectric properties decreased with increasing the amount of $Ga_2O_3$. The solubility limit of $Y_2O_3$ is 0.5mol% in this system. The electro-mechanical coupling factor$(K_p)$ and dielectric constant(${\varepsilon}_r$) were 58.6% and 1755 when the amount of $Y_2O_3$ are 0.5mol%.

• 한국재료학회지
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• 제17권2호
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• pp.68-72
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• 2007

Optimum compositions for piezoelectric properties of $(Bi_{0.5}Na_{0.5})_{(1-x)}Ba_xTiO_3$ ceramics were investigated in the range of $x=0{\sim}0.1$ covering rhombohedral to tetragonal phase regions. No impurity phases other than a perovskite phase were found and the grain size decreased with increasing x. A two-phase coexisting morphotropic phase area rather than boundary dividing rhombohedral and tetragonal phase regions appeared to exist at $x=0.05{\sim}0.08$. As for piezoelectric properties within morphotropic phase compositions, the piezoelectric constant ($d_{33}$) and the electromechanical coupling factor ($K_p$) showed peak values at x=0.065, 192 pC/N and 34%, respectively, indicating x=0.065 as an optimum composition for piezoelectric $(Bi_{0.5}Na_{0.5})_{(1-x)}Ba_xTiO_3$ ceramics.

• 전기전자학회논문지
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• 제24권1호
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• pp.260-268
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• 2020

본 논문에서는 스위칭 시 발생하는 턴-온 및 턴-오프 손실을 줄일 수 있는 LS-ZVS-LSTC를 이용한 D급 SEPP형 고주파 공진 인버터에 대해서 나타내고 있다. 본 논문에서 제안한 LS-ZVS-LSTC를 이용한 고주파 공진 회로의 해석은 무차원화 파라메타를 도입하여 범용성 있게 기술하였다. 또한 제안 인버터의 운전 특성은 무파원화 제어 주파수(μ), 무차원화 부하시정수(τ), 결합계수(κ) 등의 제어 파라메타를 이용하여 특성 평가를 수행하였다. 특성 평가를 통한 특성치를 토대로 1.8[kW] D급 SEPP형 LS-ZVS-LSTC 고주파 인버터 설계 기법의 일예를 제시하였으며, 이론 해석의 정당성은 실험을 통해 입증하였다.

• 한국전기전자재료학회논문지
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• 제22권9호
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• pp.766-771
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• 2009

Lead-free $0.94(Na_{0.5}K_{0.5})NbO_3$-0.06Ba$(Ti_{0.9}Sn_{0.1})O_3$ [0.94NKN-0.06BTS] ceramics doped with 1 mol% $MnO_2$ were synthesized by a conventional solid state method. The phase transitional behavior and piezoelectric properties of the ceramics sintered at various temperatures were investigated. The 0.94NKN-0.06BTS ceramics sintered at $1050^{\circ}C$, having morphotropic phase boundary of orthorhombic and tetragonal phases, exhibited a microstructure with abnormal grain growth. A diffused phase transition behavior for all the specimens was verified as high degree of diffuseness (${\gamma}$) values from 1.45 to 1.79. A high piezoelectric constant of $d_{33}=256$ pC/N and a satisfactory electromechanical coupling factor of $k_p=42%$ were obtained for the relatively dense 0.94NKN-0.06BTS ceramics sintered at $1050^{\circ}C$.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.456-462
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• 2015

본 연구는 토네이도와 축류펌프의 원리를 적용하여 마중물 없이 슬러리를 송출할 수 있는 새로운 펌프기술 개발을 목적으로 한다. 개발한 로터형 슬러리 펌프는 전동모터, 구동축 및 커플링, 로터, 임펠러 그리고 흡입 및 송출관으로 구성된다. 청수를 이용한 성능실험에서는 로터의 설계조건에 따른 송출량, 소비 전력량 그리고 흡입관 부압특성에 대해 모터의 회전수를 변수로 검증하였으며, 시멘트를 이용하여 제조한 슬러리의 고형물 농도에 따른 송출량 특성에 대한 검증연구를 수행하였다. 로터의 직경과 높이가 커지면 송출량과 소비되는 전력량은 증가하지만 흡입관 부압은 감소하였으며, 송출량과 부압에 미치는 로터 두께의 영향은 거의 나타나지 않았다. 개발지표로 제시하였던 18 % 이상의 고형물 농도에서도 슬러리의 송출이 가능함을 확인하였다.

• 한국결정성장학회지
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• 제6권4호
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• pp.532-542
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• 1996

Floating zone(FZ)법으로 육성하고 annealing한 undoped $LiNbO_3$ 단결정 및 MgO 또는 ZnO를 첨가한 $LiNbO_3$ 단결정의 전기적,광학적 특성을 조사하였다. 전기전도도, 유전율 및 전이온도, 전기.기계결합계수등의 전기적 특성과 광투과율, 굴절율 등의 광학적 특성을 측정하였으며, 비선형 광학특성의 척도라 할 수 있는 비선형 굴절율을 이론적으로 계산하였다. Undoped $LiNbO_3$ 단결정과 MgO 또는 ZnO를 첨가한 $LiNbO_3$ 단결정의 전기적, 광학적 특성을 비교함으로서 MgO 또는 ZnO의 첨가가 $LiNbO_3$ 단결정의 전기적 및 광학적 특성에 미치는 영향을 조사하였다.