• 전자공학회논문지SC
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• 제43권6호
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• pp.33-39
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• 2006

적, 녹, 청색 3파장 LED를 적용한 LCD 백라이트 조명은 백색 LED를 적용한 것에 비해 넓은 색재현성과 LCD 투과율을 실현할 수 있으나, 온도 변화에 따른 휘도 저하와 색좌표 변동 문제 등의 신뢰성을 확보하지 않으면 안된다. 본 논문에서는 정전류 전원을 사용하는 소형 3파장 LED 백라이트 조명에 온도 보상 소자로서 써미스터를 사용한 저가형 온도 보상 장치에 대해 소개하고, 설계 및 실험 결과를 나타내었다. 이 방법에 의해 휘도 저하율을 54% 개선하였고, 색좌표 변동율을 51% 줄일 수 있었다.

• 전자공학회지
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• 제22권3호
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• pp.92-105
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• 1995

각 분야에서 고화질 고해상도의 Flat Panel Display(FPD)에 대한 요구가 급증하고 있으며, FPD 소자들도 다양하다. FPD를 위한 구동방식은 근본적으로 matrix addroessing 방식을 사용하지만 FPD 소자의 동작 원리, 특성, 구동상의 문제점 등에 따라서 구동방식도 매우 다양하다. 다양한 FPD 소자들이 구동 방식과 구동회로를 다 살펴볼 수 없으므로 본고에서는 FPD소자인 PDP, EL, LED, EC, LCD, DMD, AMA, GLV, FED 등의 동작 원리를 설명하고, 이 소자들 중에서 AMLCD와 dc-PDP 소자의 구동방식과 구동회로에 대하여 논의한다. AMLCD의 구동방식으로는 펄스 구동 방식과 용량 구동 방식을 살펴보고, AMLCD의 문제점들을 극복할 수 있는 방법들을 설명한다. dc-PDP의 구동 방법인 pulse-memory 구동방식과 새로운 pulse-memory 구동 방식을 살펴보았다.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.402-403
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• 2009

A variety of power reduction technologies is introduced and the benefits of the technologies are discussed. PenTile$^{(R)}$ DBLC (Dynamic Brightness LED Control) combined with SABC (Sensor-Based Adaptive Brightness Control) enables to achieve the average LED power consumption to one third. The panel power reduction of 25% can be achieved with low power driving technology, ALS (Active Level Shifter). MIP (Memory In Pixel) is expected to be useful in transflective display because the whole display area can be utilized in reflective mode with power consumption of 1mW.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2009년도 9th International Meeting on Information Display
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• pp.121-124
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• 2009

We developed a panel of innovative solution-based approaches for synthesis of multicomponent sulfide phosphor materials. The application of these synthesis strategies allowed for preparation of high-purity and high-brightness $BaAl_2S_4:Eu$ and $Ba_2SiS_4:Eu$ phosphors and led to the discovery of new phosphors suitable for application in the LED-based lighting including $Sr_2ZnS_3:Eu$, $CaBaSiS_4:Eu$ and $(Ba,Sr)_2ZnS_3:Eu$.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2008년도 춘계학술대회 논문집
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• pp.222-224
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• 2008

BLUs(Backlight Units) are major component in LCD(Liquid Crystal Display) industry which occupies 90% or more of worldwide FPD(Flat Panel Display) market. And BLU market is expected to be expanded continuously according to the trend of miniaturization, slimness, low power consumption and low weight. The larger the BLU market scale, the more important standardization of performance evaluation techniques to clearly prescribe the product specification. This document is a generic specification of measurement methods of LED BLU for LCDs. It defines general procedures for quality assessment and gives general rules for measuring methods of LED BLU for LCDs.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 하계학술대회 논문집
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• pp.294-298
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• 2000

As the LED or LCD technology has been developed, if we use LED or LCD pannel, more wide color range coluld be obtained as CRT monitor. Specially, full color LED display is developed by high brightness blue LED. It can be applicable to display pannel with a long-life, wide visible angle and high brightness. A display pannel shows the images of CRT monitor performed by the main computer. Graphic application in the main computer is therefore more important in the market. Conventional 3D STUDIO, one of graphic softwares, has difficulties in manipulating and understanding the specific terminology so that one may need more time to learn it. We, therefore, developed graphic application which can recycle the conventional 3D images by creating or editing the image easily.

• 제어로봇시스템학회논문지
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• 제22권5호
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• pp.382-388
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• 2016

When Flat Panel Display (FPD) is made with backlight module, such as LED TV, it inherently suffers from the non-uniform backlight luminance problem that results in un-even brightness distribution throughout the TV screen. If the luminance of each pixel location of a TV screen as a function of the driving voltage can be measured, it can be used to compensate the non-uniformity of the backlight module. We use a carefully calibrated imaging system to take pictures of a TV screen at different levels of brightness and generate the compensation functions for the driving circuitry to correct the luminance level at each pixel location. Making use of the fact that the luminance of the screen is normally brightest at around the center of the screen and gradually decreases toward the border of the screen, the luminance of the whole TV screen is approximated by a mathematical function of the pixel locations. The parameters of the function are computed in the least square sense by the values of both the pixel luminance sent from the driving circuit and the grayscale value measured from the image taken by the imaging system. To justify the correction system, a simple second order polynomial function is used to approximate the luminance across the screen. When the driving circuit voltage is corrected according to the measured function, the variance of the screen luminance is reduced to one tenth of the one measured from the un-corrected TV screen.

• 한국콘텐츠학회:학술대회논문집
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• 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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• pp.602-606
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• 2008

LCD는 BLU를 통해 빛을 공급받고 공급 받은 빛은 각각의 칼라필터에 의해 색을 부여받으며 상판과 하판 glass 사이의 액정을 제어함으로서 빛의 양을 조절한다. 하지만 액정의 구조적 물리적 특성상 빛을 완벽히 차단하는 것은 현재 불가능하므로 광학 sheet와 액정을 통과하면서 많은 양의 손실을 겪게된다. 이는 에너지 효율과도 관련이 있으며 더 나아가 Contrast에도 큰 영향을 미치게 되어 다른 디스플레이 장치에 비해 Contrast ratio가 상당히 낮아질 수 있다. 이에 따른 해결 기술이 많이 개발되고 있으나 근본적인 해결책이 될 수 없었다. 그 중 한가기 예가 LCD에 적용되는 Dimming 기술로서 본 논문은 소비전력을 감소시키면서 영상의 화질을 적절히 표현하기 위하여 LCD의 광원으로 사용되는 LED BLU에서 분할구동(Local Dimming)을 하기위해 요구되는 영상처리 알고리즘을 제안한다. 제안 알고리즘은 고속 신호처리가 가능한 FPGA를 이용하여 영상신호로부터 분할된 영역의 최대 밝기신호를 추출하고, BLU의 분할된 영역을 추출된 밝기로 개별 점등하는 동시에 분할영역의 밝기에 상응하는 영상신호를 생성 LCD Panel에 공급함으로써 명암비가 향상된 영상을 표현한다.

• Asian Journal for Public Opinion Research
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• 제9권2호
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• pp.188-211
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• 2021

Decreasing response rates to traditional survey methods, like face-to-face and telephone interviews, have led survey practitioners around the world to seek new ways of conducting surveys in recent years." The COVID-19 pandemic exacerbated this problem because it made conducting face-to-face interviews even more difficult than before. For example, it made conducting face-to-face surveys infeasible in 2020 in South Korea, and so the Korean Academic Multimode Open Survey (KAMOS) was unable to conduct a planned face-to-face survey to recruit new panel members. The entire 8,514-member panel, established via two-stage probability-based sampling from 2016 to 2019, was invited to take three online/telephone surveys in 2020. Of these panel members, 1,352 responded to at least one survey in 2020. To test to what extent the panel remained representative of the adult South Korean population, we compared the two groups of panel members: those who responded to at least one survey in 2020 and those who did not. After weighting both groups on the basis of age, sex, and geographical area, we analyzed their responses to some of the questions that were asked during multiple rounds of the face-to-face panel-recruiting interviews. Using Cohen's d for survey items that could be analyzed numerically and Cramér's V for categorical items, we were able to conclude that the respondents to the 2020 surveys were equivalent to the non-respondents in terms of both demographics and in the answers they originally gave to substantive questions on a variety of topics related to social science or public opinion research, including questions about quality of life, societal issue, and politics (Cohen's d items <0.2, 95% CI; Cramér's V items <0.1, 95% CI). This analysis may provide a model for others who wish to test the continued representativeness of their panel or who would like to use a different survey mode or change some other aspect of their methodology and test whether it is equivalent to their former methodology. Our success in building a panel that retained its representativeness may be useful to those in other countries where face-to-face surveys had previously been the norm but are becoming increasingly difficult to conduct.

• Transactions on Electrical and Electronic Materials
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• 제17권5호
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• pp.306-309
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• 2016

The Cs₃Sb photocathode was formed by non-vacuum process technology. An in-situ vacuum device was fabricated successively with flat cesium antimonide photocathode emitters fabricated in a process chamber. The electrical properties of the device were characterized. Electron emission from the devices was induced by photoemitted electrons, which were accelerated by an anode electric field that was shielded from the photoemitter surface. The electrical characteristics of the devices were investigated by measuring the anode current as a function of device operation times with respect to applied anode voltages. Planar blue LED light with a 450 nm wavelength was used as an excitation source. The results showed that the cesium antimonide photocathode emitter has the potential of long lifetime with stable electron emission characteristics in panel devices. These features demonstrate that the cesium antimony photocathodes produced by non-vacuum processing technology is suitable for flat cathodes in panel device applications.