• Transactions on Electrical and Electronic Materials
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• 제3권1호
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• pp.38-41
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• 2002

We have investigated current-voltage-luminance characteristics of organic light-emitting diodes based on TPD/Alq$_3$organics depending on the application of forward-backward bias voltage. Luminance-voltage characteristics and luminous efficiency were measured at the same time when the current-voltage characteristics were measured. We have observed that the current-voltage characteristics shows a reversible current maxima at low voltage, which is possibly not related to the emission from Alq$_3$. Current-voltage-luminance characteristics imply that the conduction luminance mechanism at low voltage is different from that of high voltage one.

• 한국통신학회논문지
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• 제21권1호
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• pp.67-79
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• 1996

This paper presents a composite luminance signal processing system for NTSC, PAL and SECAM standards. Eaxh of the three standards employs its own specifications of subcarmier bandwidth and luminance signal waveform. The proposed system, compatible to the specifications of the three standard and B/W TV, implements variable freqneucy characteristics by controlling filter coefficients. The major features of the system are a luminance/chroma separation unit and an aperture compensation unit. The luminance/chroma separation unit employes a notch filter selection a trap freqneyc to atenuate unwanted color signals in luminance signal bands. The aperture compensation unit comprises two subunits, to provide clear color definition for each of the three standards: a primary compensation circuit and a variable compensation circuits. The proposed system yields a 40 dB gain from the chroma/luminance separation and a 10 dB gain from the aperture compensation unit.

• KIEAE Journal
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• 제9권6호
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• pp.65-72
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• 2009

Lighting for outdoor advertising is very common feature of building facades as they provide the information and commercial identification. As the interest of improving street beautification more widely, application of various lighting technologies has been develop for advertisement such as electric sign board and signage. Furthermore, the installation of higher sign luminance than needed has many negative consequences, including higher energy consumption and light pollution. There are now no standard for outdoor advertisements in terms of luminance, and installation of indiscreet outdoor advertisement without luminance consideration is becoming more commonplace. This study was to evaluate the luminous characteristics of outdoor advertising as a function of sign and building facade luminance, luminance ratio. Data were collected on 8 electric sign boards, 20 internally illuminated, externally illuminated, neon, and channel letter signs and 4 commercial areas. Photometric measurements were taken by CS-100(Minolta) and ProMetric-1400(Radiant Imaging) for various sign modes and sign design. Also luminance of building facades were analyzed according with CIE standard of maximum obtrusive light permitted for exterior lighting installations. The findings are as follows; (1) There were excessive luminance of electric sign boards that could affect adjacent building facade and night sky luminance. (2) Sings that are externally illuminated providing an inappropriate amount of light on to the outer surface of the sign caused higher building facade luminance and potential of unnecessary glare.

• 한국디지털건축인테리어학회논문집
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• 제12권2호
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• pp.33-38
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• 2012

The purpose of luminance measurement in lighting design of urban scale is to prevent light trespass and light pollution, caused by over-bright. Specially, the illumination of road, tunnel and sports complex as urban infrastructure is measured by international standard for illuminance and luminance. It has been used the spot luminance meter and the image photometer to define the characteristics of qualitative and quantitative in exterior lighting. This study introduced the concept of HDR Image, procedure of HDR Image creation and analysis. Applications of HDR Image, particularly within the apartment building exterior lighting design analysis, have been demonstrated. The procedure proposed in this study is a affordable method that is useful for the assessment of luminance distribution in the scene with electric light. It also provides a measurement capability with the high resolution luminance data within a large field of view efficiently and quickly, which is not possible to achieve with a luminance meter.

• 전기학회논문지
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• 제57권1호
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• pp.88-91
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• 2008

Electroluminescent(EL) devices based on organic thin films are considered to be one of the next generation of flat-panel displays. In this paper, we have investigated electro-luminescent(EL) characteristics of organic EL device using $Alq_3$, PBD as emitting material. Current and luminance can be seen that express a similar relativity in voltage and could know that luminance is expressing current relativity.

• 한국전기전자재료학회논문지
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• 제20권2호
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• pp.178-182
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• 2007

Electroluminescent (EL) devices based on organic thin films are considered to be one of the next generation of flat-panel displays. In this paper, we have investigated electro-luminescent (EL) characteristics of organic EL device using $Alq_{3}$, PBD as emitting material. Current and luminance can be seen that express a similar relativity in voltage and could know that luminance is expressing current relativity.

• Journal of Information Display
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• 제11권2호
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• pp.39-44
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• 2010

The time dependences of the luminance properties of 55-inch CCFL and LED backlights and 32-inch FFL backlights with LCD panels were investigated during the warm-up time from the cold start. The long-term luminance maintenance curve of a standard CCFL was examined in a time window up to 5000 hours. These two time dependences are important characteristics from the viewpoint of initial picture quality and lifetime reliability, respectively. Empirical equations were suggested for the analysis of the time dependence of these luminance data. These approaches are expected to be helpful in predicting the luminance properties of backlights based on the luminance data obtained in a limited time window.

• 한국화재소방학회논문지
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• 제33권6호
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• pp.181-185
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• 2019

본 연구에서는 유도등의 광원과 경년변화에 따른 휘도성능을 분석하기 위하여 사무실, 상가, 병원, 공장 등에 설치된 유도등을 발취하여 CCFL, LED광원별 경년변화에 따른 휘도성능을 분석하였다. 이는 유도등과 같은 전기적 특성을 갖는 소방제품은 설치된 곳의 주위온도나 습도, 먼지 등이 그 성능에 변화를 줄 수 있기 때문에 설치장소별로 발취하여 그 특성을 분석하였다. 실험결과, CCFL유도등은 대형, 중형, 소형 모두 '휘도비 2'정도의 값을 나타내었다. 기술기준 규정값이 '휘도비 9이하'인 점을 감안할 때 매우 양호한 값을 나타냈으며, 경년변화에 의한 휘도비 변화도 거의 없음을 확인할 수 있었다. LED유도등은 '휘도비 5'정도의 값을 나타냈으며, 이는 표시면의 빛이 균일하지 못함을 뜻한다. 또한 경년변화에 의한 휘도비 변화는 거의 없으나, 휘도비의 값은 LED유도등보다 크게 나타났다. 이는 시각적인 측면에서는 만족스럽지 못한 결과이다. 이를 개선하기 위해서는 LED광원의 빛 분산이 필요하며 휘도비 관련 규정을 강화할 필요가 있다.

• E2M - 전기 전자와 첨단 소재
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• 제10권2호
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• pp.150-155
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• 1997

Powder type electroluminescent device(P-ELD) in this study was prepared by printing method. P-ELDs were basically composed of phosphor, insulator and transparent conducting layer. The phosphor powder was prepared by sintering the mixture of ZnS as a host, Cu as an activator, and NaCl as a flux for co-activator and enhancement of growth of the phosphor particles. The phosphor layer was made by printing the paste of the cyanoethylpullan as a binder and the ZnS system phosphor powder. In order to evaluate the luminescence characteristics of ZnS P-ELD, applied voltage - luminance(V-L), frequency-luminance(f-L), and relative luminance spectra(L- .lambda.) characteristics were measured. The experimental results show that luminance increased with increasing the applied voltage and frequency. It can be explained in terms of the potential barrier formed between ZnS and CuS. Two emission peaks in luminance-wavelength spectra measured at applied voltage of 100 $V_{rms}$ were observed at 500nm as a primary peak and 460nm as a secondary peak, respectively.y.

• KIEAE Journal
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• 제8권6호
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• pp.21-26
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• 2008

According to the tendency of energy efficiency and environment-friendly chracteristics, demend of High-efficiency lighting using LED(Light Emitting Diode)are being increased actively and applied in various fields. However, In order to adequate application of LED light sources, it is necessary to lighting environment and luminous characteristics of LED light sources. This Study aims to characterize the work-plane lighting environment by LED light sources comparing with fluorescent light sources which are widely used. For the sake of this study, a fluorescent light source and 5 LED light sources were introduced and luminance and correlated color temperature were measured to evaluate luminance contrast. The experimental model is Mock-up which is $4.9m{\times}7.2m$ with a height of 2.9m. The test room was set up partition and desks. Luminance and correlated color temperature were measured work-plane on the desk which was set up local lighting by the Radiant Imaging ProMetric 1400. The optical characteristics data of LED can give a lot of advantages to design LED lighting appliances. Hereafter, the object of research will be conducted to evaluate effects of LED light sources on working performance, survey of visual performance, preference and physiology of subjects.