• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.198-202
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• 2001

In this study, contour vibration mode piezoelectric transformer with size of 27.5${\times}$27.5${\times}$2.6mm$^3$ using PNW-PMN-PZT ceramic was fabricated. And the piezoelectric transformer was adopted to fluorescent lamp ballast circuit. Electrical characteristics of the piezoelectric transformer were investigated for fluorescent lamp ballast application. The electrical properties and characteristic temperature rise were measured using oscilloscope and infrared temperature sensor. A 28W fluorescent lamp was successfully driven by the fabricated ballast circuit. After driving the lamp using ballast circuit for 24 min, the output power, efficiency and characteristic temperature rise of piezoelectric transformer showed the appropriate values of 28.85[W], 86.3[%] and 15[$^{\circ}C$], respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.07a
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• pp.847-851
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• 2000

In this study, contour-vibration-mode Pb($Ni_{1/2}$,$W_{1/2}$)$O_3$-Pb(Zr,Ti)$O_3$ piezoelectric transformers for driving a 28W(T5) fluorescent lamp were fabricated to the modified filter structure with ring and dot electrodes which has been developed for application in 455kHz AM radios. The piezoelectric transformers were fabricated to the size of $31.5$\times$31.5$\times$2.5$mm^3$ with the variations of ring/dot electrode area ratio. Driving of piezoelectric transformer was carried out with input region for the ring electrode and output region for the dot electrode. The electrical properties and characteristic temperature rises caused by the vibration were measured at various load resistances. A 28 W fluorescent lamp, T5, was successfully driven by the fabricated transformer. The transformer with ring/dot electrode area ratio of 1.83 exhibited the best properties in terms of output power, efficiency and characteristic temperature rise, 30.95 W, 97.57% and8.3$^{\circ}C$ respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05c
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• pp.135-139
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• 2001

Contour vibration mode piezoelectric transformers were designed and fabricated to the square plate with size of $27.5{\times}27.5{\times}2.5(2.6,\;3.0)mm^3$ using PNW-PMN-PZT ceramics. Electrical characteristics of the piezoelectric transformer were investigated for fluorescent lamp ballast application. The electrical properties and characteristic temperature rise were measured using oscilloscope and infrared temperature sensor. A 28W fluorescent lamp was successfully driven by the fabricated transformers. After driving the lamp using Power Amplifier for 24 min, the output power, efficiency and characteristic temperature rise of PT2 piezoelectric transformer showed the appropriate values of 28.01 W, 99.43% and $11^{\circ}C$, respectively. The electronic ballast using PT2 piezoelectric transformer showed an excellent output power of 28.85 W and efficiency of 86.3%, respetively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.14 no.9
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• pp.736-743
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• 2001

Contour vibration mode piezoelectric transformers were designed and fabricated to the square plate with size of 27.5x27.5x2.6㎟ using PNW-PMN-PZT ceramics. Electrical characteristics of the piezoelectric transformer were investigated for fluorescent lap ballast application. The electrical properties and characteristic temperature rise were measured by oscilloscope and infrared temperature sensor. A 28W fluorescent lamp was successfully driven by the fabricated transformers. The electronic ballast using piezoelectric transformer showed an excellent output power of 28.85[W], efficiency of 86.3% and characteristic temperature rise of 15[$\^{C}$].

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.3
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• pp.91-96
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• 2014

Modern electronic circuits are becoming more vulnerable to damage by surges, and it is required to improve the impulse withstand voltage performance of electrical and electronic equipment. This paper presents the impulse withstand voltage performance of lighting equipment connected to power lines, and the impulse withstand voltage tests for fluorescent lamp, LED lamp and halogen lamp were carried out according to the reference standards under normal service conditions. To conduct performance tests against lightning surge, a combination wave ($1.2/50{\mu}s$ voltage - $8/20{\mu}s$ current) was employed. The test surge was applied between lines or between line and ground of the specimen to be measured. The test surge was applied synchronized at the peak value of the positive and negative AC voltage waves. As a consequence, some specimens satisfied the impulse withstand voltage test criteria, but lighting equipment such as 36W fluorescent lamps, 5W and 5.5W LED lamps and 50W halogen lamp were damaged at the test voltage levels between power lines. It is needed to improve the qualities of lighting equipment to satisfy EMC immunity requirements of equipment for general lighting purposes.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.1
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• pp.70-79
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• 2003

In this paper, T5 28-watt fluorescent lamp ballast using a piezoelectric transformer is fabricated and its characteristic is investigated. Developed electronic ballast is composed of basic circuits and blocks, such as rectifier part, active power factor corrector part, frequency oscillation part using microcontroller and feedback control, piezoelectric transformer and resonant half bridge inverters. The fabricated ballast uses to variable frequency methode in external so exciting that the frequency of piezoelectric transformer could be generated by voltage control oscillator using microcontroller(AT90S4433). The current of fluorescent lamp is detected by feedback control circuit. The signal of inverter output is received using Piezoelectric transformer, and then its output transmitted to fluorescent lamp. Traditional electromagnetic ballasts operated at 50-60Hz have been suffered from noticeable flicker, high loss, large crest factor and heavy weight. A new electronic ballast is operated at high frequency about 75kHz, and then Input power factor, distortion of total harmonic and lamp current crest factor are measured about 0.9!35, 12H and 1.5, respectively Accordingly, the traditional ballast is by fabricated electronic ballast using piezoelectric transformer and voltage control oscillator because of its lighter weight, high efficiency, economic merit and saving energy.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.228-232
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• 2002

In this paper, In order to solve the problem is proposed using a new type of electronic ballast that the traditional magnetic ballasts operated at 50-60Hz have been suffered from noticeable flicker, high loss, large crest factor and heavy weight which is composed of rectifier, active power corrector, series resonant half bridge inverter, micro-controller and piezoelectric transformer for driving for driving T5 fluorescent lamp were manufactured. The proposed electronic ballast operated at high frequency (about 75kHz) shows a input power factor of more than 0.995, total harmonic distortion of less than $12\%$ and lamp current crest factor of less than 1.5, respectively. Output power and efficiency showed 28w and $85\%$, respectively. Accordingly, it is considered that the ballast using piezoelectric transformer can replace the typical electronic ballast.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.1
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• pp.28-35
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• 2001

In this paper, an electronic starter and controller are develor:ed for blinking and color variation oI:'||'&'||'pound;fations of fluorescent ]arrps, which would be suitElble for use in an advertising panel. The deve1oporl electrornc starters enable single-pulse ignition for fluorescent lamps of 2O-4Q[W] according to the start signal of controller, and the lamp life is e;.qxccted to go beyond 3,OCO hours with blinking o]:ffations for minimum 0.2[s]. Also, the controller based on a micro-controller can handle up to 128 fluorescent lanlpS and have ten modes of blinking pattems and 7-color variation mxles.

• Environmental Engineering Research
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• v.18 no.1
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• pp.21-28
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• 2013

In this study, the applicability of visible light-emitting-diodes (LEDs) to the photocatalytic degradation of indoor-level trichloroethylene (TCE) and perchloroethylene (PCE) over N-doped $TiO_2$ (N-$TiO_2$) was examined under a range of operational conditions. The N-$TiO_2$ photocatalyst was calcined at $650^{\circ}C$ (labeled N-650) showed the lowest degradation efficiencies for TCE and PCE, while the N-$TiO_2$ photocatalysts calcined at $350^{\circ}C$, $450^{\circ}C$, and $550^{\circ}C$ (labeled as N-350, N-450, and N-550, respectively) exhibited similar or slightly different degradation efficiencies to those of TCE and PCE. These results were supported by the X-ray diffraction patterns of N-350, N-450, N-550, and N-650. The respective average degradation efficiencies for TCE and PCE were 96% and 77% for the 8-W lamp/N-$TiO_2$ system, 32% and 20% for the violet LED/N-$TiO_2$ system, and ~0% and 4% for the blue LED/N-$TiO_2$ system. However, the normalized photocatalytic degradation efficiencies for TCE and PCE for the violet LED-irradiated N-$TiO_2$ system were higher than those from the 8-W fluorescent daylight lamp-irradiated N-$TiO_2$ system. Although the difference was not substantial, the degradation efficiencies exhibited a decreasing trend with increasing input concentrations. The degradation efficiencies for TCE and PCE decreased with increasing air flow rates. In general, the degradation efficiencies for both target compounds decreased as relative humidity increased. Consequently, it was indicated that violet LEDs can be utilized as energy-efficient light sources for the photocatalytic degradation of TCE and PCE, if operational conditions of N-$TiO_2$ photocatalytic system are optimized.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.11a
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• pp.451-455
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• 2003

최근 LCD제품은 고유한 특장인 경박단소가 요구되면서, 기존의 Back Light Unit(BLU) 로는 대응할 수 없는 사양으로 진화되고 있다. 기존과 동일한 설계개념으로 접근시에 시장에서 요구되는 중량, 두께, 휘도의 사양을 만족시킬 수 없으며, BLU의 주요광원인 CCFL(Cold Cathod Fluorescent Lamp)의 휘도 개선 또 한 한계에 다다르고 있다. 따라서 앞으로의 BLU 의 고성능화는 최적화, 고효율화로의 개발 전개가 예상되며, LCD의 고해상도에 따른 투과율 저하를 보상하기 위한 고품질 BLU의 개발이 시급한 상황이다. 본 연구에서는 이러한 BLU의 고효율화, 고품질화를 달성하기 위한 고성능 도광판 개발과 관련하여, 실물 제작에 앞서 광학시뮬레이션을 통한 이론적 접근을 수행하였다. 연구 결과, 상측에서 정각 $90^{\circ}$ 에 높이 $50{\mu}m$ 하측에서 정각 $80^{\circ}$ 높이 $28{\mu}m$일때 평균조도가 71.52W/m^2 구현됨을 알 수 있다. 이 결과를 바탕으로 통상의 인쇄 방식 도광판에 비해서 약 20% 정도의 휘도향상이 가능함을 알 수 있었다. 또한 차후 본 결과를 바탕으로 한 실물 제작을 통해 설계 시뮬레이션 결과와의 비교를 통해서 정확한 예측이 가능한 시스템을 구현함을 목적으로 하였다.