• 전기학회논문지
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• 제58권10호
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• pp.1947-1953
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• 2009

Metal halide (MH) lamps have been largely used due to high luminous efficiency, good color rendering, and long life. Since the metal halide lamps have problems of high ignition voltage and acoustic resonance. Thus, the design of ballast is very difficult for engineers. This paper proposes prototype of electric ballast in order to solve above two problems. The proposed electric ballast is consisted of EMI filter, full wave rectifier circuit, active PFC, DBI(Dual Buck Inverter), dimming circuit and ignitor circuit. The DBI supplies both rectangular voltage and current to the lamp. As the result of the experiment, the acoustic resonance was eliminated and the ignitor circuit was designed to generate high ignition voltage than 5kV. It makes the dimming circuit possible to control the lamp power in range between 230W and 350W.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.34-39
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• 2004

Fluorescent lamp operated at high frequency by the electronic ballast provide ballasts like unnoticed flicker effect and higher luminous efficiency. This paper presents analysis of Half-Bridge type resonant inverter for Fluorescent lamp drive for stable characteristic and life improvement of lamp operated at high frequency. Also, it has described an electronic ballast design with the capability of high PF (Power Factor) and low THD (Total Harmonic Distortion). The validity of designed electronic ballast circuit is confirmed by simulation and experimental results. The Designed electronic ballast is implemented successfully on 32W Fluorescent lamp system.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집
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• pp.130-132
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• 2001

We have investigated current-voltage(I-V) characteristics of organic light-emitting diodes based on TPD/Alq$_3$ organics depending on the application of forward-reverse bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the I-V characteristics were measured. We have observed that the I-V characteristics shows a current mxima at low voltage, which is possibly not related to the emission from Alq$_3$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 C
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• pp.1515-1516
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• 2006

The low luminous efficacy is one of the major demerits of plasma display panel (PDP). In this work we propose the new driving method for high efficiency AC-PDP and analyze its discharge characteristics. The suggested method can control the effective capacitance of panel by external circuit. As a result of the new suggested method, the current becomes less and the discharge time becomes long, because of voltage distribution between panel and auxiliary capacitor. So this method can decrease the power consumption much more than that of the conventional driving method.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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• pp.493-494
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• 2006

We have demonstrated highly efficient WOLED with two separated emissive layers using a blue fluorescent dye and a red phosphorescent dye. we also obtain stable $CIE_{x,y}$ coordinates with two-layered WOLEDs. The device structure was ITO/2-TNATA/NPB/two separated emissive layers/Bphen/Liq/Al. The maximum luminous efficiency of the device was 11.6 cd/A at $20\;mA/cm^2$ and $CIE_{x,y}$ coordinates varied from (x = 0.33, y = 0.37) at 6V to (x = 0.28, y = 0.35) at 14V.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.1043-1048
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• 2006

This paper aimed to verify and develop lighting design data for offices in Korea. It focused on a Korean standard office value relative to lighting density and the evaluation of lighting energy and cooling load. When planning indoor lighting design, we generally utilize the lighting density value which is set $14W/m^2$ by the ASHRAE/IES standard office value. However, the value is not appropriate to apply in Korea where higher efficiency lamps are more popular than others. For calculation of a proper lighting density of Korea, we analysed distribution curves of luminous intensity(2-lamp fluorescent lighting fixture with Parabolic) and derived the new lighting density $12.64W/m^2$ as Korea standard office value. In the simulation using this value, it was shown that lighting energy and cooling load could be reduced.

• 반도체디스플레이기술학회지
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• 제20권2호
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• pp.73-76
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• 2021

This thesis described the optical and electrical properties of the alternating current powder electroluminescent device based on Ag nanowire as a transparent electrode. The Ag nanowire electrode showed the morphology of 20 nm in diameter and 15 ㎛ in length. The transparent electroluminescent devices that were fabricated using the nanomilled ZnS : Cu, Mn phosphor by bar-coating process showed the transmittance of 67%. In order to improve the luminous efficiency, it is necessary to apply the transparent dielectric layer and increase the amount of the nanophosphor while maintaining the transmittance.

• 한국전기전자재료학회논문지
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• 제27권1호
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• pp.50-55
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• 2014

It was firstly found in 1st group element. Recently, it has been reported on the improvement of efficiency of the OLEDs by introducing thin layer of some carbonate materials of alkali metal. In order to improve the efficiency of OLEDs which is one of the next generation displays, we have studied the electrical characteristics of the device depending on the thickness ratio of the hole-injection layer to the electron-injection layer. Teflon-AF was used as the hole-injection material, and alkali-metal carbonates of $Li_2CO_3$ were used as the electron-injection materials. To obtain a proper thickness ratio, we manufactured. Four types of devices with the thickness ratio of HIL to EIL were made to be 1 : 4, 2 : 3, 3 : 2, and 4 : 1. The results of electrical and optical properties showed that the device with the thickness ratio of 4 : 1 is the most excellent result. In addition, to prepare a four-layer device by inserting the ${\alpha}$-NPD is a hole transporting material was compared with three-layer element. As a result, the maximum luminance, the maximum luminous efficiency, maximum external quantum efficiency of about 124 [%], 164 [%], 106 [%] improve was confirmed.

• 한국응용과학기술학회지
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• 제32권1호
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• pp.1-6
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• 2015

본 연구에서는 발광층의 전자와 정공의 재결합 영역을 확인하고, 단계적 도핑구조를 이용하여 여기자들의 효율적인 분배를 통해 roll-off 효율을 감소시켜서 녹색 인광 유기발광다이오드의 수명 증가를 나타냈다. 발광층 내 호스트는 양극성의 4,4,N,N'-dicarbazolebiphenyl (CBP)를 사용하여 전하의 이동을 원활하게 하였다. 발광층을 네 구역으로 분할하여 각각 소자를 제작하였고, 네 구역의 도판트 농도에 따라 발광효율과 수명 향상을 보였다. 이로써 발광층 내의 단계적 도핑구조를 이용하여 캐리어와 여기자들이 원활하게 분배된 것을 확인하였다. 기준소자 대비 발광층의 도판트 농도를 5, 7, 11, 9% 순서로 단계적 도핑구조를 적용한 device C의 수명이 약 73.70% 증가하였고, 휘도 효율은 51.10 cd/A와 외부 양자 효율은 14.88%의 성능을 보였다.

• 조명전기설비학회논문지
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• 제20권7호
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• pp.6-13
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• 2006

각 종 전자 디바이스의 투명전도막으로 많이 사용되는 ITO 및 ZnO:Al 박막을 스퍼터링법에 의해 제작하였다. 가스압력 및 기판온도 등의 최적조건하에서 제작된 ITO 및 ZnO:Al 박막은 각각 $1.67{\times}10^{-3}[{\Omega}-cm]$ 및 $2.2{\times}10^{-3}[{\Omega}-cm]$의 비저항율과 89.61[%] 및 90.88[%]의 가시광 영역에서의 광투과율을 나타내었다. ZnO:Al과 ITO 투명전극을 이용하여 5인치의 PDP 셀을 동일한 제조조건하에서 제작하였다. ZnO:Al의 경우 Ne(base)-Xe(8%)의 가스 혼합비, 그리고 400[Torr]의 압력조건에서 가장 잘 동작되었으며, $200{\sim}300$[V]의 인가전압 범위에서 $836[cd/m^2]$의 평균휘도를 나타내었다. 고휘도 및 저 소비전력특성을 위한 중요한 파라메타인 광효율은 전원 주파수가 $10{\sim}50[Khz]$의 범위에서 $1.2{\sim}1.6[lm/W]$정도를 나타내었으며, ITO의 경우 휘도 및 광 발생 효율은 약 10[%]정도 상승하였다.