• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.368-375
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• 2000

For safety reason ATS(Automatic Train Stop) system is being used, which is a kind of communication system with a feedback amplifier and a transformer on the train and wayside coils. The coils are highly resonant LC circuits, also have very high Q(Quality) factors. The Q factors of wayside ATS coils are to be maintained high enough for the amplifier to operate reliably. In this paper a novel Q measurement system is proposed. The system measures the resonant frequency and the bandwidth of the ATS coils, by controlling the phase difference between the transformer and the coil using digital PLL(Phase Locked Loop). The overall configuration and algorithms of the proposed system and the digital PLL control schemes are presented in details. The experimental waveforms are shown to verify the system performances.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.981-984
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• 2001

The piezoelectric properties of 0.05pb(A $l_{0.5}$N $b_{0.5}$) $O_3$-0.95Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$+0.7wt%N $b_2$ $O_{5}$ +0.5wt%Mn $O_2$ceramics with the additives of BaC $O_3$were investigated. For the additions of BaC $O_3$, the dielectric constant ($\varepsilon$$^{T}$ $_{33}$ ), the piezoelectric constant ( $d_{33}$ ), the electromechanical coupling factor ( $k_{p}$ ), and . the mechanical quality factor ( $Q_{m}$ ) were increased, but dielectric loss (tan$\delta$) was decreased. The highest piezoelectric properties and dielectric properties were observed at the sintered temperature of 120$0^{\circ}C$ and 0.4 wt% of BaC $O_3$, and the properties of $d_{33}$ , $k_{p}$ , and $Q_{m}$ were 339(x10$^{-12}$ C/N), 59% and 1754, respectively.vely.y.y.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.255-256
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• 2007

In the study, in order to develop low temperature sintering ceramics for multilayer piezoelectric actuator, PMN-PNN-PZT ceramics were fabricated using $Na_2CO_3,\;Li_2CO_3$ as sintering aids and their dielectric and piezoelectric properties were investigated according to the variations of $MnO_2$ as additives and sintering aids. At the sintering temperature of $900^{\circ}C$ and 0.1wt% $MnO_2$ as sintering aids, density, electromechanical coupling factor$(k_p)$, mechanical quality factor$(Q_m)$, piezoelectric constant$(d_{33})$, and dielectric constant $({\varepsilon}_r)$ showed the optimum value of $7.87[g/cm^3]$, 0.61, 1131, 1127 and 376, respectively, for multilayer piezoelectric actuator application.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 추계학술대회 논문집
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• pp.294-296
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• 1999

Solid solution ceramics having various ratios between xPb( $Y_{1}$2/T $a_{1}$2/) $O_3$ and Pb(Z $r_{0.52}$ $Ti_{0.48}$) $O_3$were synthesized by a conventional solid state reaction for well sintered specimens, dielectric and piezoelectric prperties were studied as a function of composition. The dielectric constant of PYT-PZT ceramics of 4 mol% PYT was 1,424 at room temperature. The maximum value of electromechanical couping facotr $k_{p}$ of 51% $k_{t}$ of 30% were obtained at the composition of 4 mol% PYT, howerver mechanical quality factor( $Q_{m}$) had a minimum value of 69 at 4 mol% PYT. Also the maximum value of piezoelectric constant of $D_{33}$(310[pC/N]) and $d_{31}$(-131[pC/N]) were obtained at the composition of 4 mol% PYT content.ntent.t.t.t.

• 한국식품과학회지
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• 제37권4호
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• pp.597-602
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• 2005

인삼 유화 음료를 3가지 온도 조건에서 저장하면서 유화안정성, 당도, 진공도, pH, 산도, 색도(L, a, b값), 점도, 사포닌, 미생물 및 관능검사 등 총 10개 항목의 품질 요소들의 변화를 측정한 결과 저장기간 중 품질 변화가 크며 저장 온도에 따른 유의차를 나타내는 4가지 품질 지표인 유화 안정성, 산도, 점도, yellowness를 확인하였다. 품질 지표로 선정한 유화 안정성, 산도. 점도, yellowness의 온도 의존성을 Arrhenius식을 이용하여 판단한 결과, 점도의 경우 온도 의존성이 가장 큰 것으로 나타났으며, 유화 안정성의 경우 2단계로 변화가 일어나 저장 초기에 속도가 빠르고, 일정 기간 이후에 속도가 느렸다. 또한 산도 및 yellowness의 변화도 저장기간에 따라 변화하고 저장 온도에 따라 그 속도가 달라짐을 확인 할 수 있었다. 일반적으로 식품의 품질 변화의 온도 의존성을 나타내는 $Q_{10}$ value는 약 2의 값을 나타낸다고 하였으나, 본 연구에서 품질 지표로 선정된 4가지 요소의 $Q_{10}$ value는 각각 다른 값을 나타내었다. 이로 보아 같은 식품이라도 품질 인자에 따라 각기 다른 $Q_{10}$ value를 가지는 것을 알 수 있었으며, 일률적으로 $Q_{10}$ value를 적용하는 것은 적절하지 않음을 알 수 있었다.

• 한국세라믹학회지
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• 제42권10호
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• pp.698-702
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• 2005

Dielectric and Piezoelectric properties of complex perovskite 0.92Pb($Zr_{1/2}Ti_{1/2})O_{3}-(0.08-x)Pb(Cu_{1/3}Nb_{2/3})O_{3}-xPb(Mn_{1/3}Nb_{2/3})O_{3}(0{\leq}x{\leq}0.080$) (PZT-PCN-PMN) system were investigated as a function of PMN content. With the increase of PMN content of the sintered specimens, tetragonal phase was coexisted with rhombohedral phase, the dielectric constant was decreased, mechanical quality factor ($Q_{m}$) was inceased, and optimal sintering temperature was increased up to 1050$^{\circ}C$. For the composition of x = 0.064 sintered at 1050$^{\circ}C$ for 2 h, 1939 of maximum mechanical quality factor ($Q_{m}$), 57$\%$ of electromechanical coupling factor ($k_{p}$), and 1100$^{\circ}C$ of dielectric constant, 0.37$\% $ of dielectric loss (tan $\delta$) were obtained.

• 한국재료학회지
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• 제13권6호
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• pp.360-364
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• 2003

$Sr_{l}$ $\pm$x/$Bi_{2}$ $\pm$y/$Ta_2$ $O_{9}$ and $Sr_{l}$ $\pm$$Bi_{x}$ $2\pm$y$Nb_2$$O_{9}$ ceramics were prepared by a solid state reaction method. X-ray diffraction analysis indicated that single-phase of Bi-layered perovskite was obtained. According to Sr/Bi content ratio, Curie temperature( $T_{c}$), electromechanical factor($K_{p}$ ) and mechanical quality factor($Q_{m}$ ) were measured. The Curie temperature of SBN(SBT) rose from $414^{\circ}C$(314$^{\circ}C$) to $494^{\circ}C$(426$^{\circ}C$) when Sr/Bi content ratio was increased. In the case of Sr/Bi content ratio = 0.55/2.3, the maximum value of the mechanical quality factor $Q_{m}$ of SBT and SBN were obtained 3320 and 1010, respectively.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.161-164
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• 2001

In this paper, we investigated the dielectric and piezoelectric properties of Pb(Sb, Nb)O$_3$-Pb(Zr, Ti)O$_3$ ceramic(PSN) for piezoelectric transformer and actuator etc. Effect of MnO$_2$ addition on the PSN ceramic was investigated. Anisotropic properties of electromechanical coupling factor and piezoelectric properties proved to be varied with amount of MnO$_2$ impurity and sintering temperature. The electromechanical coupling factor k$_{p}$ of 0.38 and the mechanical quality factor Q$_{m}$ of 1944 were obtained from the specimen with 0.4 wt% MnO$_2$ sintered at 115$0^{\circ}C$ addition. Experimental results indicated that the PSN ceramic with MnO$_2$ impurity can be effectively used for piezoelectric transformer and actuator.tor.

• 한국음향학회지
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• 제19권3호
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• pp.63-71
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• 2000

본 논문에서는 표준 대역통과 필터와 무증폭 바이패스 이득의 조합을 이용한 구조에 근거하여 전문가용 디지털 오디오에 적합한 정교한 주파수응답을 갖고, 실시간 시스템에서 적은 계산량과 메모리로 구현이 용이한 2차 디지털 픽킹 필터의 설계방식을 제안하였다. 이와 같이 설계된 디지털 픽킹 필터는 이득요인에 따라 필터의 대역폭이 왜곡되는 단점을 Q-보정을 통해 제거하였으며, 컨포말 변환에 의한 설계보다 수학적으로 간단하고 구현이 용이하며, 적은 계산량 및 메모리를 필요로 한다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1997년도 추계학술대회 논문집
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• pp.405-408
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• 1997

The microwave dielectric properties of CuO and CdO addition of BiNbO$_4$ceramics were investigated. As the content of CdO increased, sintered density and quality factor is decreased. With increase in sintering temperature, the dielectric constant and quality factor is increased. In case of specimen sintered at 96$0^{\circ}C$ with 0.03 wt% CuO and CdO, the microwave dielectric properties obtained were dielectric constant of 41.2, quality factor (Q$\times$f) of 6, 500, temperature coefficient of resonant frequency of ppm/$^{\circ}C$.