• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 1999년도 춘계학술대회 논문집
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• pp.621-625
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• 1999

Rosen type piezoelectric transformer for LCD backlight operated at high voltage and low current, may not be sucessfully used for illuminating general fluorescent lamps because low voltage and high current are required. In this study, the piezoelectric transformer with width vibration mode operated at low voyage and high current was designed for the application of fluorescent lasso ballast. The step-up ratio and efficiency as a function of the load resistance in the piezoelectric transformer indicated that the transformer can be effectively used for the electronic ballast for low profile fluorescent lamp.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.1209-1211
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• 2000

This paper presents a PSPICE circuit model for the simulation of both static and dynamic characteristics of fluorescent lamps. The model can by utilized for an electric ballast simulation with continuous dimming and transient mode simulation such as step dimming Characteristics of a Rosen-type piezoelectric transformer were analyzed by combining an equivalent circuit with piezoelectric equations and the relation between the characteristics and the dimension of the PT was studied.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.630-633
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• 2001

This paper presents a PSPICE circuit model for the simulation of both static and dynamic characteristics of fluorescent lamps. The model can by utilized for an electric ballast simulation with continuous dimming and transient mode simulation such as step dimming Characteristics of a Rosen-type piezoelectric transformer were analyzed by combining an equivalent circuit with piezoelectric equations and the relation between the characteristics and the dimension of the PT was studied.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1511-1514
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• 2002

This paper presents design and construct of flat type step-down piezoelectric transformer for the application to AC adaptor. This piezoelectric transformer operated in resonance vibration mode. In this paper, finite element method(FEM) was used for analysing piezoelectric transformers. Stress and electric field of the transformer were simulated at resonance frequency. Using this simulation results, we manufactured improved Rosen type piezoelecric transfomer and measured its output characteristics. As results, output power was linearly increased by increasing input power at resonance frequency and it was found that the transformer an invariable output power for input power. From these results, we expect that this piezoelecric transfomer can be applied to small size and low capacitive AC adaptor.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 Proceedings ICPE 01 2001 International Conference on Power Electronics
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• pp.47-51
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• 2001

In this paper, we have explained electrical characteristics of a step-down Rosen type piezoelectric transformer for AC-adapter. When the electric voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, then output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. From the piezoelectric direct and converse effects, symbolic expressions between the electric inputs and outputs of the step-down piezoelectric transformer have derived with an equivalent circuit model. With the symbolic expressions, load and frequency characteristics have discussed through simulation. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformers were measured under the various conditions of loads and frequencies. First we measured resonant frequency from impedance curve and got equivalent impedance value of the piezoelectric transformer from admittance plot. It was shown from experiments that output voltage has increased and resonant frequency has changed according to various resistor loads. Output current has decreased inversely proportional to changing of loads. Moreover, the measured values of output voltage and current are well agreed with the simulated values of the proposed equivalent circuit model.

• 한국전기전자재료학회논문지
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• 제13권3호
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• pp.220-226
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• 2000

The piezoelectric material for piezoelectric transformer needs the high electromechanical coupling factor( $k_{p}$) the piezoelectric constant( $d_{33}$) and the mechanical quality factor( $Q_{m}$)in order to obtain high voltage step-up ratio and low temperature rising. In this study the piezoelectric transformers were fabricated using Pb［$Zr_{0.45}$/ $Ti_{0}$48//L $u_{0.02}$(M $n_{1}$3//S $b_{2}$3/)$_{0.05}$］ $O_3$(PMS-PZT) and Pb［Z $r_{0.25}$/ $Ti_{0.375}$(M $g_{1}$3//N $b_{2}$3/)$_{0.375}$］ $O_3$+0.5wt%Mn $O_2$(PMN-PZT) ceramics. The piezoelectric properties of PMS-PZT and PMN-PZT were measured. The voltage set-up ratios of the piezoelectric transformers using PMS-PZT and PMN-PZT were the value of 15, 20 respectively under 100$_{KΩ}$ in Rosen type transformer.r.ormer.r.r.r.r.r.r.

• 대한미생물학회지
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• 제15권1호
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• pp.77-84
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• 1980

본 연구는 한국인 및 한국 각지의 가축에 대한 reovirus 2형의 혈구응집저지항체의 분포를 알어보고저 실시된 연구이다. 사람의 피검물은 1979년 6월부터 12월까지 시내 종합병원에 래원한 신검대상자 총 614명과 한국각지의 가축(돼지) 총 877수를 대상으로 하였다. 돼지의 혈액은 1977년 6월부터 동년 9월까지 전국 25개 지역에서 채취했다. 이들에 대한 혈청을 분리하여 $-20^{\circ}C$에 보관하면서 실험하였고, 혈구응집저지시험은 Rosen(1960b, 1974)의 수기를 따랐다. 항원(Reovirus 2형)은 이호왕(1975) 교수로부터 분양받어 본 교실에서 HeLa 세포에 계대하여 혈구응집가를 확인하여 사용했다. 실험 결과는 다음과 같다. 1. 한국인 총 614명의 Reovirus 2형에 대한 10배 이상 HI항체 보유율은 73.29%로서 한국인이 높은 항체를 보유하고 있었다. 그리고 남녀비는 남자(76.47%)가 여자 (65.12%)보다 약간 높은 경향을 보였다. 2. 연령별로 본 한국인의 항체 보유율은 전 연령군에 고루게 분포되어 있었으나 41세에서 50세군이 85.71%로 약간 높았다. 3. 월별 항체보유율은 6월이 93.22%로 높았고, 10월이 47.62%로 낮았다. 4. 한편 한국의 25개 지역의 총 877수의 돼지에 분포된 항체보유율은 61.80%(542수)였다. 이를 도별로 구분한 바 서울이 83.37%로 가장 높았고, 가장 낮은 지역은 충남으로 40%였다. 5. 월별로 검출된 돼지의 항체보유율은 6월(63.21%)부터 9월(72.25%)까지 사이에 점차 증가되어 가는 경향을 보였다. 6. 사람과 돼지에 분포한 HI 항체가는 그림 2와 같이 대부분이 1:20이내에서 1:80이내에 분포하였으며 상호 차가 있었다. 이상의 실험결과를 토대로 볼때 한국자연계에는 Reovirus 2형이 광범하게 분포되어 있음을 알 수 있었으며, 한국인 및 가축(돼지)에 있어서 높은 항체가를 보유하고 있다는 사실을 새로히 알 수 있었다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2003년도 춘계전력전자학술대회 논문집(1)
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• pp.279-282
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• 2003

In this paper, to apply piezoelectric transformer for PDA backlight inverter, piezoelectric transformer using the composition which $Nb_2O_5$ added into PNW-PMN-PZT ceramics was fabricated as Rosen-type one with the size of $1165mm^3$. And their electrical characteristics were investigated with the variations of load resistance and driving frequency And then, the driving circuit for PDA CCFL(0.6W) which composed of the two MOSFETs connecting in series was manufactured using piezoelectric transformer, VCO and one-chip microprocessor. After driving for 25 min using the proposed circuit for PDA CCFL(0.6W), driving frequency of 214.4kHz, input voltage of 31.78 V and input current of 21.1mA were shown. And then, output voltage of 293.2 V and output current of 2.2mA were shown. At the same time, efficiency of 96.2$\%$ and temperature rise of $3.6^{\circ}C$ were appeared at the piezoelectric transformer.

• 한국전기전자재료학회논문지
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• 제17권3호
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• pp.289-293
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• 2004

PNW-PMN-PZT ceramics were fabricated with the variations of Nb$_2$O$_{5}$ addition and their microstructural and piezoelectric characteristics were investigated. When the amount of Nb$_2$O$_{5}$ increased, grain size decreased gradually. At 0.3wt％ Nb$_2$O$_{5}$ which is the same weight percent with Fe$_2$O$_3$, maximum tetragonality(c/a) and density were shown due to the complexed doping effects. Also, this composition that showed Qm of 2,041, kp of 0.55, grain size of 2.5${\mu}{\textrm}{m}$ and $\varepsilon$r of 1704 were proper for high power application. Using this composition, Rosen-type piezoelectric transformer was fabricated as the size of 1 ${\times}$ 16 ${\times}$ 5㎣ and its electrical characteristics were investigated with the variations of load resistance and driving frequency. At the resistance of 200㏀, maximum step-up ratio of 13.68 was shown. After driving PDA CCFL for 25 min using the inverter circuit, at driving frequency of 214.4KHz, input voltage of 31.78 V and input current of 21.1mA were measured at the input part of piezoelectric transformer. And then, output voltage of 293.2 V and output current of 2.2mA were shown at the output part of piezoelectric transformer. At the same time, efficiency of 96.2％ and temperature rise of 3.5$^{\circ}C$ were appeared at the piezoelectric transformer.ormer.

• The Korean Journal of Ceramics
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• 제5권2호
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• pp.171-177
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• 1999

In the $(Pb_{1-x}M_x)[(Mn_{1/3}Sb_{2/3})_{0.05}Zr_yTi_{0.95-y}]O_3$ system, where M=Ca and Sr, the piezoelectric properties were evaluated to examine the possibility of application to piezoelectric transformer. A Rosen-type piezoelectric transformer was formed, then the electrical properties of voltage step-up ratio, frequency characteristics etc. were analysed. The morphotropic phase boundary was determined to be y=0.475 in $Pb[(Mn_{1/3}Sb_{2/3})_{0.05}Zr_yTi_{0.95-y}]O_3$ system and the piezoelectric properties of this composition was kp=0.59, Qm=1600 and $\varepsilon_r$=1150. Moreover, when 1-2 mol% of Sr are substituted, enhanced piezoelectric properties of kp=0.61, Qm=1600 and $\varepsilon_r$=1400 were shown. The temperature rising (ΔT) of a piezoelectric transformer with $Pb[Mn_{1/3}Sb_{2/3})_{0.05}Zr_{0.475}Ti_{0.475})]O_3 $ composition was $10^{\circ}C$, and the voltage step-up ratio was 500 when the output voltage was 4000V, whereas the ΔT was below $3^{\circ}C$ and the resonant frequency variation ($\Delta f_r$) as a function of load resistance was below 5% when the output voltage was 2000 V. These characteristics are superior to the properties of materials, which were substituted by Ca or without substitution.