• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2006년도 6th International Meeting on Information Display
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• pp.1813-1818
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• 2006

We demonstrate a new approach to form gradient hole injection layer (HIL) in organic light-emitting diodes (OLEDs). Single spincoating of hole-injecting conducting polymer compositions with a perfluorinated ionomer results in gradient workfunction through the layer by self-organization, which lead to remarkably efficient single layer polymer light-emitting diodes (PLEDs) (${\sim}21$ cd/A). The device lifetime was significantly improved (${\sim50$ times) compared with the conventional hole injection layer, poly(3,4-ethylenedioxy-thiophene)/polystyrene sulfonate. This solution processed HIL also produced dramatically enhanced luminous efficiency (${\sim}34$ cd/A) in vacuum- deposited green fluorescent OLEDs while the vacuum deposited HIL gave the luminous efficiency of ${\sim}23$ cd/A in the same device structure.

• 교육시설
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• 제9권5호
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• pp.13-21
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• 2002

Daylighting in educational environment is very important as it has an effect on students' performance as well as in their visual health. It is regarded as a good energy conservation method in saving energy used for lighting. This study conducted initial daylight measurements to analyze luminous environment in classrooms of Korean elementary school. The results indicated that the typical classroom had a reasonable level of daylight. However, it also found that the classroom had some problems of the uniformity of illuminance and the contrast of brightness of surfaces in the classroom. It is argued that daylighting design for school classroom should consider these aspects to make daylit classrooms ideal so as to provide comfortable visual environment.

• 전기학회논문지
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• 제61권11호
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• pp.1650-1655
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• 2012

AC-PDPs have recently achieved good performance and their image quality can sufficiently compete with the LCD TV. However, it is necessary more effort to improve the luminance and luminous efficacy in the PDP technology. The gas mixture ratio plays a very important role in discharge characteristics, but the mechanism of gas discharge is complex and complicated. In this paper, we investigate the mechanism of gas discharge with Ne+Xe miture ratio through zero and two dimensional fluid simulation.

• 한국태양에너지학회 논문집
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• 제22권4호
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• pp.26-34
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• 2002

Daylighting in building is very important as it has an effect on work performance as well as on their visual health. It is also regarded as a good energy conservation measure in saving energy used for lighting. There are many daylighting evaluation tools such as empirical equations, tables, nomograms, diagrams, protractors, computer simulation, scale models. This study conducted initial daylight measurements to analyze luminous environment in classrooms of elementary school and comparative analysis on three daylighting evaluation tools, such as daylight factor calculation formula, the graphic method with BRE Protractor and computer simulation with Adeline 3.0. It is found that the computer simulation tool produced the closest result to actual measurements of luminous environment in elementary school classroom, and the other simplified tools made appropriate results so that they can be used in the early stage of daylighting design process.

• 반도체디스플레이기술학회지
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• 제22권2호
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• pp.81-86
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• 2023

Recently, there has been an increased demand for light-emitting diode (LED) due to the growing emphasis on environmental protection. However, the use of GaN-based sapphire in LED manufacturing leads to the generation of defects, such as dislocations caused by lattice mismatch, which ultimately reduces the luminous efficiency of LEDs. Moreover, most inspections for LED semiconductors focus on evaluating the luminous efficiency after packaging. To address these challenges, this paper aims to detect defects at the wafer stage, which could potentially improve the manufacturing process and reduce costs. To achieve this, image processing and deep learning-based defect detection techniques for Sapphire Epi-Wafer used in Green LED manufacturing were developed and compared. Through performance evaluation of each algorithm, it was found that the deep learning approach outperformed the image processing approach in terms of detection accuracy and efficiency.

• 한국건축시공학회지
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• 제23권4호
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• pp.393-404
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• 2023

본 연구에서는 구리입자를 이용한 항균 UV경화도료를 제조하고 투명성을 평가한 결과 일반 UV경화도료와 동등이상인 90%이상의 전광선투과율을 나타내었다. 실란커플링제로 표면 개질한 구리입자가 20wt% 첨가된 항균 UV경화도료를 코팅한 항균 목질 마루판의 피로 시험 전후의 항균 성능 평가 결과 6시간 후 세균감소율이 99.9% 로 우수한 항균 성능을 나타내었다.

• 새물리
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• 제68권11호
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• pp.1268-1274
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• 2018

항공장애등이란 비행 중인 조종사에게 건축물이나 위험물의 존재를 알리기 위해 사용되는 등화를 말한다. 현재 대부분의 항공장애등의 광원은 발광다이오드(light-emitting diode, LED)로 대체되었고, 급격하게 확장 및 보급되었으나, 설치된 항공장애등이 광학적 성능 기준을 충족하지 못하여 항공 수송기기의 충돌 사고를 유발하고 있으며, 이러한 이유로 항공 안전상의 위험에 노출되어 있는 실정이다. 이러한 문제를 해결하기 위하여 본 연구에서는 $360^{\circ}$ 방향에서 동일한 광도 분포를 가지고, LED 광원에서 나오는 광선을 좁은 빔(beam) 발산각으로 시준할 수 있는 프레넬 렌즈(fresnel lens)를 각각의 비구면 조각의 집합 (array) 형태로 설계를 하였다. 그 후에, 렌즈 기울기(tilt), LED와 프레넬 렌즈 사이의 거리를 최적화하여 중심 광도 20,000 cd, $3^{\circ}$ 이상의 수직 빔 발산각을 구현하는 항공장애등 광학계 설계와 시뮬레이션을 진행하였다.

• Transactions on Electrical and Electronic Materials
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• 제6권5호
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• pp.221-224
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• 2005

To overcome of poor electron injection in organic light-emitting diodes (OLEDs) with Al cathode, a thin layer of inorganic insulating materials, like as LiF, is inserted between an Al cathode and an organic electron transport layer. Though the device, mentioned above, improves both turn on voltage and luminescent properties, it has some problems like as thickness restriction, less than 2 nm, and difficulty of deposition control. On the other hand, Li organic complex, Liq, is less thickness restrictive and easy to deposit and it also enhances the performance of devices. This paper reports the improved electron injection on OLEDs with another I A group metal complex, Potassium quinolate (Kq), as an electron injection material. OLEDs with organic complexes showed improved turn-on voltage and luminous efficiency which are remarkably improved compared to OLEDs with Al cathode. Especially, OLEDs with Kq have longer life time than OLEDs with Liq.

• Journal of Information Display
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• 제11권4호
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• pp.154-159
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• 2010

Single-sustainer driving is an AC PDP driving scheme to reduce the circuitry by maintaining the sustain electrode at ground level. To date, however, the research on the discharge characteristics in such driving scheme is insufficient. In this study, the panel performance and discharge characteristics of the single-sustainer driving scheme were observed while varying the address electrode condition. In single-sustainer driving, the address electrode is strongly involved in the sustain discharge when the former is maintained at ground level, and the dependence of the luminous efficacy on the sustain voltage is different from that in the conventional driving scheme. The dependence of the luminous efficacy on the sustain voltage appeared similar, however, to that in the conventional driving scheme when the address electrode was floated in single-sustainer driving. In the investigation of the temporal evolution of the sustain discharge using an IICCD camera, it was found that the sustain discharge in single-sustainer driving with a floating address electrode is similar to that in the conventional driving scheme, and the strong plasma formation region was located in the vicinity of the MgO surface, which seems to be related to the lifetime of a PDP with single-sustainer driving. In the investigation of the operation characteristics, the PDP that was operated with a floated address electrode showed a narrower dynamic operation margin, but a longer lifetime was expected.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전기물성,응용부문
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• pp.201-203
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• 2005

To improvement the performance of PDPs, we developed an ac-PDP with new fence structure. By measuring minimum sustaining voltage(Vs), discharge current(Ion), discharge(Ioff), and brightness of the light from a 4-inch at-PDP, performances of the conventional structure and proposed structure are compared. The experimental results show that the test panel with the proposed new fence structure shows high luminance by 10%, and high luminous efficiency by 30% compared with the conventional structure at the Ne-Xe(8%) gas mixture of 400 torr.