• Journal of Korea Multimedia Society
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• v.10 no.10
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• pp.1271-1283
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• 2007

To detect defect of FPD(flat panel displays) is very difficult due to uneven illumination on FPD panel image. This paper presents a method to detect various types of defects using the approximated image of the uneven illumination by B-spline. To construct a approximated surface, corresponding to uneven illumination background intensity, while reducing random noises and small defect signal, only the lowest smooth subband is used by wavelet decomposition, resulting in reducing the computation time of taking B-spline approximation and enhancing detection accuracy. The approximated image in lowest LL subband is expanded as the same size as original one by wavelet reconstruction, and the difference between original image and reconstructed one becomes a flat image of compensating the uneven illumination background. A simple binary thresholding is then used to separate the defective regions from the subtracted image. Finally, blob analysis as post-processing is carried out to get rid of false defects. For applying in-line system, the wavelet transform by lifting based fast algorithm is implemented to deal with a huge size data such as film and the processing time is highly reduced.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• v.21 no.1
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• pp.47-54
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• 1993

The major positive sea surface temperature(SST) anomalies not only occur in the region with the most moisture increase, but also in the flank of the area with sinking motion in the Subtropics. As the large amount of water vapor has been increased by the SST anomaly, the increased of the SST is expected to destabilize the air and leads under moist adiabatic unstable conditions, to an enhanced development of moisture cluster. The 4.0 K change of SST causes the positive difference of Brightness Temperature(TB) of about 10.0k for water vapor channels of TOVS over the north eastern and central tropical Pacific Ocean, but the negative difference of TB of about 7.5 K is shifted southward and southeastward to Southern Pacific Ocean along the equator correspondingly. The difference of the TBs for IR water vapor channel $11(7.3{\mu}m)$ and $12(6.7{\mu}m)$ of TOVS indicative of the moisture distribution during two time periods(January 1983 and 1984), leads us to infer significant changes in the entire tropospheric circulations and the dynamic processes over the Pacific Ocean.

• The Journal of the Korea Contents Association
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• v.15 no.8
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• pp.69-76
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• 2015

With Various signs are installed at roadside to display the message which rather confuse the drivers. The technologies using advanced lighting system and LED have improved the visibility at nighttime but the problems with plural signs have yet to be resolved. In order to solve this problem, LED and the prismatic variable message sign have been applied. But, they have been provided limited information by the display limit. This research conducted to study patent and technical trend of the existing variable message signs to understand the present technology. And, we suggested next generation display to improve providing information. Therefore, we conducted to compare the LED and the OLED by technical and economical literature review. Also, this research conducted test of luminance contrast about the LED and the OLED display in order to understand the possibility of replacing road signs.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.12
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• pp.34-40
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• 1999

In conventional color television systems color edges of highly saturated color pictures are deteriorated because of bandwidth limitation of the color-difference signal. In this paper a modified hue-weighted luminance demodulation method with low noise is proposed for the edge correction. The weighting coefficients are given by ratios of the gadient of color-difference signal to the gradient of band-limited luminance signal. Proposed method is theoretically complete for the 1st order lowpassed color-difference signals and well separated luminance/chrominance signal. Noise reduction technique is also considered because of impulse noise generation in the gradient ratio processing of noisy pictures. In computer simulation with noisy pictures proposed technique gives a visual effect of the bandwidth expansion and detail improvement in highly saturated color edge area.

• Journal of the Korean Vacuum Society
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• v.10 no.1
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• pp.98-103
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• 2001

A new application of dirchroic mirror for the improvement of luminance and luminous efficacy in an AC-Plasma Display Panel (PDP) is suggested. Only about half of the Vacuum Ultraviolet (VUV) generated in the reflective PDP cell is used for the excitation of the phosphor. We are suggesting an idea of adopting a dichroic mirror which can reflect the VUV toward the phosphor which otherwise is absorbed by the front panel. The optical constants of the thin films of dirhroic mirror were determined from the photometric measurements through an iteration process of matching calculated and measured values of the reflectance and transmittance in the VUV wavelength region. From these results, we could design such a filter whose high reflection zone is centered at 147nm by a computer simulation accurately. The 147nm VUV is radiated from Xenon 3Pl state which is dominantly used to activate the phosphor in the PDP cell. The dichroic mirror was made with an electronbeam evaporator and its reflectance was measured by a reflectometer. We confirmed the usefulness of the dichroic mirror for the improvement of efficiency with experiments done by test panels. The panel with mirror shows improved luminance and luminous efficacy by 20∼30％.

• Korean Journal of Remote Sensing
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• v.24 no.6
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• pp.535-549
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• 2008

Vicarious calibration for the satellite sensor relies on simulated TOA (Top-of-Atmosphere) radiances over various targets. In this study, TOA visible radiance was calculated over ocean targets which are located in five different regions over the Indian and Pacific ocean, and its possible use for the satellite sensor calibration was examined. TOA radiances are simulated with the 6S radiative transfer model for the comparison with MODIS/Terra and SeaWiFS measurements. Geometric angles and sensor characteristics of the reference satellites were taken into account for the simulation. AOT (Aerosol Optical Thickness) from MODIS/Terra, pigment concentrations from Sea WiFS, and ozone amount from OMI measurements were used as inputs to the model. Other atmospheric input parameters such as surface wind and total column water vapor were taken from NCEP/NCAR reanalysis data. The 5-day averaged radiances over all targets show that the percent differences between simulated and observed radiances are within about ${\pm}5%$ in year 2005, indicating that the calculated radiances are in good agreement with satellite measurements. It has also been shown that the algorithm can produce the SeaWiFS radiances within about ${\pm}5%$ uncertainty range. It has been suggested that the algorithm can be used as a tool for calibrating the VIS bands within about 5% uncertainty range.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.4 s.316
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• pp.60-69
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• 2007

The human eye usually experiences a loss of color sensitivity when it is subjected to high levels of luminance, and perceives a discrepancy in color between high and normal-luminance displays, generally known as a hue shift. Accordingly, this paper models the hue-shift phenomenon and proposes a hue-correction method to provide perceptual matching between high and normal-luminance displays. The value of hue-shift is determined by perceived hue matching experiments. At first the phenomenon is observed at three lightness levels, that is, the ratio of luminance is the same between high and normal-luminance display when the perceived hue matching experiments we performed. To quantify the hue-shift phenomenon for the whole hue angle, color patches with the same lightness are first created and equally spaced inside the hue angle. These patches are then displayed one-by-one on both displays with the ratio of luminance between two displays. Next, the hue value for each patch appearing on the high-luminance display is adjusted by observers until the perceived hue for the patches on both displays appears the same visually. After obtaining the hue-shift values, these values are fit piecewise to allow shifted-hue amounts to be approximately determined for arbitrary hue values of pixels in a high-luminance display and then used for correction. Essentially, input RGB values of an image is converted to CIELAB values, and then, LCh (lightness, chroma, and hue) values are calculated to obtain the hue values for all the pixels. These hue values are shifted according to the amount calculated by the functions of the hue-shift model. Finally, the corrected CIELAB values are calculated from corrected hue values, after that, output RGB values for all pixels are estimated. For evaluation, an observer's preference test was performed with hue-shift results and Almost observers conclude that the images from hue-shift model were visually matched with images on normal luminance display.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.171-174
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• 2022

자동차의 전기차로의 전환과 더불어 IT 기술이 접목된 자율주행기술이 빠르게 발전하고 있으며, 현대기아자동차 그룹을 비롯한 글로벌 완성차 제조사 및 애플, LG 등과 같은 IT 제조사간에 완성도 높은 자율주행차 개발에 치열한 경쟁이 이루어지고 있다. 특히 사람의 개입이 거의 없는 4단계 이상의 자율주행 기술이 적용된 자율주행차는 운전석이 없는 등 기존과는 매우 다른 실내 구조를 가질 것으로 예상되며, 사람에게 움직이는 생활공간을 제공할 것으로 기대된다. 이와 같은 자율주행차 내의 미디어 소비는 고화질 미디어를 대형 화면으로 볼 것으로 예상되며, 지상파 TV 방송은 미디어를 단방향으로 대용량 전송하는데 유리하여 자율주행차를 대상으로 미디어 서비스에 적용성이 높을 것으로 기대된다. 본 논문은 이러한 미래 자율주행차가 제공하는 움직이는 생활공간에서 TV를 시청하는 '이동TV'를 염두에 두고, 현재의 4K-UHDTV 시대 및 미래의 8K/Post-8K 시대의 비용 효과적인 지상파 TV 방송망 기술을 소개한다.

• Photonics industry news
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• s.35
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• pp.10-13
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• 2006

발광다이오드(LED)산업은 21세기 빛의 산업으로 세계시장에서 매우 유망한 산업의 하나이며, 국가성장을 위한 미래전략산업의 하나다.LED라는 것은 반도체에 전압을 가할 때 생기는 발광현상으로 빛을 내는 조명방식인데 기존의 조명과는 달리 무한대의 색과 높은 휘도를 낼 수 있다. 아울러 고유 가시대에 에너지 절감과 환경보호효과가 커서 새로운 차세대 광원으로 떠오르고 있다.

• The Bulletin of The Korean Astronomical Society
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• v.33 no.2
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• pp.40.2-40.2
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• 2008