• 한국전기전자재료학회논문지
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• 제19권12호
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• pp.1099-1105
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• 2006

In this paper, the equivalent circuit model of a Rosen-type multilayer piezoelectric transformer(MPT) has been proposed based on the Mason's equivalent circuit model and the principle of single layer piezoelectric plate. From the piezoelectric direct and converse effects, the symbolic expressions between the electric inputs and outputs of the MPT have been derived from the equivalent circuit model. A simplified equivalent circuit model of the MPT whose driving part has a single input form has been proposed. The symbolic expressions of the driving part have been derived from the simplified equivalent circuit model and the model was compared with the multi-input equivalent circuit model through the simulation. In the comparisons between the simulation results and the experimental data, output voltage is 630 Vp-p in case of 11-layered MPT and 670 Vp-p for 13-layered MPT over the experiment range. As the load resistance increases, output voltage increases and saturates over $300k{\Omega}$ and the resonant frequency changes from 102 kHz to 103 kHz. The simulation and the experimental results agree well over different load resistances and frequencies.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.218-218
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• 2008

최근 미관을 위하여 소형 네온관 등이 사용되고 있다. 따라서 네온관 등 구동에 사용되는 인버터는 안정기 역할을 하면서 소형화와 경량화가 중요한 요소이다. 본 연구는 압전 특성이 우수한 PZT계 세라믹스 조성인 $(Pb_{0.94}Sr_{0.06})[(Ni_{1/2}W_{1/2})_{0.02}(Mn_{1/3}Nb_{2/3})_{0.07}(Zr_{0.51}Ti_{0.49})_{0.91}]O_3$에 특성 향상을 위해 PbO, $Fe_2O_3$, $CeO_2$, Xwt% $Nb_2O_5$ 조성별로 첨가하였으며 그에 따른 유전, 압전 특성을 조사하고 또한 Rosen type의 압전 트랜스포머를 제작하여 각 조성별 변환효율을 측정하였다. 실험방법은 일반적인 세라믹스 제조공정으로 파우더 혼합 후 24시간 ball milling하고 $850^{\circ}C$ 에서 2시간 하소 후 $1230^{\circ}C$에서 2시간 소결하였다. 또한 최종 소결 시편을 이용하여 Rosen type의 압전 트랜스포머를 제작하였다. 상 분석을 위해 XRD를 이용하여 perovskite구조를 확인하고 미세구조확인을 위해 SEM으로 관찰하였다. 압전 특성을 평가하기 위해 압전 $d_{33}$ Meter를 사용하였으며, Impedence analyzer HP 4194A를 이용하여 전기적 특성을 측정하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2008년도 추계학술대회 논문집 Vol.21
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• pp.222-223
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• 2008

Recently, piezoelectric transformer is applied to wide fields. Multi layer piezoelectric transformer has the advantage of high step up ratio, high electromechanical coupling coefficient(Kp) and high mechanical quality factor(Qm), however it shows the peeling-phenomenon of electrode, and high price due to high sintering temperature. Therefore this study focus on the method for fabrication of high power rosen type piezoelectric transformers. The composition of $0.01Pb(Ni_{1/3}Nb_{2/3)O_3$ - 0.08Pb$(Mn_{1/3}Nb_{2/3})O_3$-0.91Pb$(Zr_{0.505}Ti_{0.495})O_3$(abbreviated as PNN-PMN-PZT) ceramics is employed for this study.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권9호
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• pp.611-615
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• 1999

Piezoelectric properties of PMN-PZT ceramics with $CeO_2$ impurity were investigated. Mechanical quality factor, $Q_m$ of 1792, 1285 and the electromechanical coupling coefficient, $k_p$ of 0.52, 0.54 were obtained from the specimen with 0.25 and 0.5 mole % $CeO_2$ respectively. Curie temperature was decreased with the addition of $CeO_2$ while the electric coercive field was proportional to the amount of impurity. Based on the system ceramics with 0.5 mole % cerium oxide, a Rosen type piezoelectric transformer was fabricated and tested. Voltage step-up ratios of 230 and 13 were obtained from the transformer at no load and $100 k\Omega$ resistance, respectively. Experimental results showed a potential of the transformer for the practical use coupled with the expected strength increase by the grain size refinement.

• 한국융합학회논문지
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• 제12권1호
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• pp.243-250
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• 2021

이온화된 기체인 플라즈마의 의료분야에서 적용은 현재 주로 살균분야에 국한되어 적용되고 있지만 바이오플라즈마기술의 등장으로 그 응용범위가 확대되고 있는 실정이다. 또한, 인체에 직접 조사하거나 비열처리하는 경우에는 정교한 시술을 위해 핸드헬드가 가능한 고밀도 소형화가 요구된다. 변압기로 인한 전자기파 영향이 없고 소형으로 구현이 가능한 형태의 로젠형 압전변압기는 압전효과를 이용한 전기-기계 커플링을 통해 전압변환을 달성하며 상대적으로 에너지밀도를 높일 수 있는 장점으로 휴대용 플라즈마 발생장치에 이용되고 있다. 본 논문에서는 로젠형 압전변압기의 등가회로를 이용한 모델링을 수행하고, 의료용으로 적용가능한 형태의 플라즈마 발생장치를 설계 및 제작하였다. 이를 위해 플라즈마 발생 모듈은 12V 입력전원으로 5.8kV의 출력전압을 발생시키도록 하프브리지 커버터 토폴로지 전력변환장치를 적용하여 고전압 동작하도록 설계하였다. 설계를 통해 제작된 프로토타입을 통해 의료용합형 플라즈마 기기로의 활용가능성에 대해 확인하였고, 이러한 연구결과를 통해 플라즈마 제트 또는 직접조사용 등의 다양한 의료기기로서의 역할을 확보할 것으로 사료된다.

• 한국경영과학회지
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• 제6권2호
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• pp.25-34
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• 1981

In this paper, we propose a non-edge following method for linear programs. Unlike alledged poor performance of algorithms of this type, this method performs well at least with 25 randomly generated problems. This method is comparable to Rosen's gradient projection method as applied to the dual formulation. The latter is of general purpose, and no implementation rules are available for linear program applications. This paper suggests ways of finding improving dual feasible directions, and of allowing to move across the extreme faces of a higher dimension polyhedron. Rather simple computational rules are provided for projection operations needed at each iteration.

• Bulletin of the Korean Chemical Society
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• 제32권12호
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• pp.4233-4238
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• 2011

Based on the exact quantization rule for the nonrelativistic Schrodinger equation, the exact quantization rule for the relativistic one-dimensional Klein-Gordon equation is suggested. Using the new quantization rule, the exact relativistic energies for exactly solvable potentials, e.g. harmonic oscillator, Morse, and Rosen-Morse II type potentials, are obtained. Consequently the new quantization rule is found to be exact for one-dimensional spinless relativistic quantum systems. Though the physical meanings of the new quantization rule have not been fully understood yet, the present formal derivation scheme may shed light on understanding relativistic quantum systems more deeply.

• 대한토목학회논문집
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• 제4권4호
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• pp.37-48
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• 1984

탱크의 수직벽(垂直壁)과 같은 정수압(靜水壓) 형태(形態)의 하중(荷重)을 받는 철근(鐵筋)콘크리트 슬래브의 극한해석(極限解析)을 수행(遂行)하기 위하여 강복선해석(降伏線解析)을 사용(使用)하였다. 슬래브의 직교이방성계수(直交異方性係數)를 사용(使用)하여 등가성(等方性) 및 직교이방성(直交異方性) 철근(鐵筋)의 경우를 모두 고려(考慮)하였으며 여러 가지 단조건(端條件)을 고려(考慮)하였다. 강복선해석(降伏線解析)은 가상(假想)일의 원리(原理)를 사용(使用)하여 수행(遂行)하였으며, 종래(從來)의 대각선(對角線)메카니즘에 비하여 좀 더 실제적(實際的)인 부채꼴메카니즘을 포함하여 4가지 붕괴(崩壞)메카니즘들에 대하여 고려(考慮)하였다. 해석결과(解析結果)는 부채골메카니즘들이 지금까지의 정수압(靜水壓)을 받는 철근(鐵筋)콘크리트 슬래브에 사용(使用)되었던 간단한 대각선(對角線)메카니즘들에 비하여 복잡하였으며, 특(特)히 본(本) 연구(硏究)에서는 Horton의 연구(硏究)를 확장(擴張)하여 제약조건(制約條件)을 받는 다변수(多變數) 비선형(非線型) 최적화문제(最適化問題)로 형성(形成)한 후 the Rosen-Brock Hillclimb Procedure Program에 의하여 해(解)를 구하였고 그 결과(結果)는 조래(從來)의 다른 메카니즘들에 비하여 정밀(精密)하였다.

• 한국전기전자재료학회논문지
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• 제19권7호
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• pp.644-649
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• 2006

This paper presents a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p\;k_{15})$ becomes effective rather than the transverse mode coupling factor $(k_{31})$. ANSYS finite element code was used to analyze transformer behavior and to optimize electrode and poling configurations. The voltage step-up ratio of the proposed transformer has been markedly improved in comparison with that of the equivalent rectangular(Rosen) type. A single layer prototype transformer, $20\sim30mm$ in diameter and $1.0\sim3.5mm$ thick, was fabricated, such as step-up ratio, power transformation efficiency, and temperature were measured. While the transformer was driving a Cold Cathode Fluorescent Lamp(CCFL), the temperature field of the transformer was also observed.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.719-720
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• 2009

We suggest a new approach to lower the operating voltage of plasma display devices using a piezoelectric transformer (PT). $Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3$ (PMNT) was used as a piezoelectric material. The Rosen-type PT, with a compact size of 10 mm ${\times}$ 20 mm ${\times}$ 0.3 mm, was fabricated on a glass substrate. The fabricated PT was operated as a half-wave vibration mode at around 80~90 kHz. The maximum voltage step-up ratio was 3 at 87.8 kHz when the input voltage was 10.32 V (peak-to-peak).