• Proceedings of the KIEE Conference
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• 2005.11a
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• pp.125-129
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• 2005

Mobile display는 사용자가 이동하면서 화면을 보기 때문에 주변 luminance의 변화에 따라서 contrast ratio 변화가 심하다. 특히 햇빛 아래에서는 Mobile display의 화면을 알아보기 어렵다. 본 연구에서는 주변 조도가 증가할수록 TFT LCD의 black 휘도의 변화율이 white 휘도 변화율보다 크게 작용하여 전체 contrast ratio(이하 CR)가 크게 감소함올 확인하였다. 또한, 반투과형 LCD는 반사창을 통해서 외부 빛올 반사시키기 때문에 주변 조도가 높아도 일정 수준의 CR은 유지할 수 있다. 그러나 투과형 LCD보다 CR이 낮았다. 본 논문에서는 투과형 TFT LCD에 back light 광원으로 LED를 사용하고, photo diode와 LED drive IC를 이용하여 주변 조도의 광량에 따라서 LCD의 back light LED의 휘도를 3단계 조절할 수 있는 회로를 구성하였다. 이렇게 함으로써 주변 조도에 따라 자동으로 back light 휘도 조절이 가능한 결과을 얻었다.

• Journal of the Korean Vacuum Society
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• v.19 no.1
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• pp.28-35
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• 2010

A new electrode structure in a plasma display panel was designed in a way to increase the bright room contrast ratio (BRCR). The area of the black matrix pattern to get a low reflection from the panel surface was enlarged using the new electrode design concept. The electrical characteristics such as firing voltage, voltage margin and power consumption were measured. The luminance of the panel was measured and the luminous efficiency was calculated. It was found that the new electrode structure was very effective to enhance the BRCR.

• Journal of Broadcast Engineering
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• v.20 no.6
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• pp.818-826
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• 2015

Recently, objective image quality assessment (IQA) methods that elaborately reflect the visual quality perception characteristics of human visual system (HVS) have actively been studied. Among those characteristics of HVS, luminance adaptation (LA) effect, indicating that HVS has different sensitivities depending on background luminance values to distortions, has widely been reflected into many existing IQA methods via Weber's law model. In this paper, we firstly reveal that the LA effect based on Weber's law model has inaccurately been reflected into the conventional IQA methods. To solve this problem, we firstly derive a new LA effect-based Local weight Function (LALF) that can elaborately reflect LA effect into IQA methods. We validate the effectiveness of our proposed LALF by applying LALF into SSIM (Structural SIMilarity) and PSNR methods. Experimental results show that the SSIM based on LALF yields remarkable performance improvement of 5% points compared to the original SSIM in terms of Spear rank order correlation coefficient between estimated visual quality values and measured subjective visual quality scores. Moreover, the PSNR (Peak to Signal Noise Ratio) based on LALF yields performance improvement of 2.5% points compared to the original PSNR.

• Journal of radiological science and technology
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• v.28 no.1
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• pp.13-17
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• 2005

In domestic nondestructive testing(NDT) field, there have recently been radiation exposure accidents due to a disregard for confirmation of the position of radioisotope during the test. In order to prevent these kinds of accidents, a scintillating film has been developed. The scintillating film that can convert gamma-ray to visible light has a function of the position detection of radioisotope in a opaque guide tube of an NDT apparatus. The aim of this study is to enhance the visibility performance of the scintillating film and find out the best configuration of the scintillating film. In order to find appropriate materials for the scintillating film, various inorganic scintillating materials were evaluated in this work. An absolute luminance of the scintillating films was measured by luminance meter for evaluation of visibility performance. Ir-192 gamma projector was used for NDT apparatus. The experiment shows that the scintillating film with reflective layer was the more effective performance for visibility. The higher mixing ratio of scintillating material to binding material, the higher luminance was measured. $Gd_2O_2S(Tb)$ inorganic powder as the scintillating materials had the best performance for visibility of the scintillating film. The developed scintillating film helps to ensure safer environment to the operators.

• Journal of the Society of Disaster Information
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• v.18 no.4
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• pp.806-816
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• 2022

Purpose: In this study, the luminance measurement analysis results of the smoke generation state are considered for visual signal display light color for real-time escape guidance in the underground common area. Method: We will analyze the scattering characteristics of light in the atmosphere and optical technology based on the visibility theory, and try to classify the elemental technology as a guidance function through a prototype of a visual signal display device for evacuation guidance. Result: In the experiment conducted under the smoke-generating condition, the results were derived with low luminance ratio and good visibility in the order of red, green, and yellow. However, this result is different from general lighting in which color rendering is considered, and is limited to signals for signals and detection. Conclusion: A conclusions were drawn by reflecting both the luminance measurement results in the smoke generation situation and the preference survey results conducted in previous studies for the light color of the visual signal for signal and detection. When events such as smoke occur, it is better to use the escape guidance visual signal in red or green.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.792-794
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• 2008

We investigated influence of gas pressure and mixing ratio on the electro-optical properties of External Electrode Fluorescent Lamp (EEFL). The experimental results indicated that luminance and efficiency became the maximum at lower gas pressure and Ar mixing ratio.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.288-291
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• 2008

This paper describes a new S-PVA cell structure which achieves enhanced contrast ratio by adopting a step-like patterned common electrode between the high sub-pixel and low sub-pixel electrodes without loss of transmittance. A 24-inch panel was developed for monitor applications and measured contrast ratio and white luminance were over 2500:1 and 400cd/m2, respectively.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1183-1186
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• 2005

A new reset method for high contrast ratio and reduction of the reset time is presented. In this new reset method, except the first subfield, a new reset pulse with only ramp-up period is adopted. In this reset method, from the third subfield, the background luminance generated during the reset period is theoretically zero until the first subfield of the following frame. Employing the new reset method, the dark room contrast ratio improved to 3084.7:1 from 189.1:1 of the conventional reset method. The new reset method reduced the required time for reset per subfield to 160us except the first subfield.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.631-634
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• 2005

We propose a new address-while-display (AWD) driving method to obtain a high contrast ratio and a wide driving margin which is composed of a short ramp reset period, a sustain period and an address period as the basic unit. The short ramp reset (SRR) pulse made it possible to assure the wide operating voltage margin and minimize the background luminance by redistributing the wall charges between address and scan electrode. As a result, a high dark room contrast ratio of 10000 to 1 could be obtained with a wide operating voltage margin of 40V for stable address.

• KIEAE Journal
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• v.6 no.2
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• pp.67-74
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• 2006

As sustainable design technologies, advanced daylighting systems with lightshelves have been developed and are currently under monitoring the daylighting performance. This study aims to evaluate the comparative daylighting performance of sloped lightshelf and conventional glazing window with mock-up model, reconstructed as a prototype of Korean office building, sized $12.0m{\times}7.3m{\times}3.7m$ ($w{\times}d{\times}h$) and $1.8m{\times}4.8m$($w{\times}h$) for the south facing side-window was installed on the rooftop of engineering building, Kyung Hee University in Korea. It has an identical configuration of reference room and the test room. For the test room, the sloped type lightshelf system was designed as 10mm transparency sheet glass, tilt angle degree $29^{\circ}$, and total sized 1.28m (interior length 0.88m, exterior length 0.49m). It consisted of daylighting collector, entrance glazing and reflector. To assess daylighting performance, the totally 37 measuring points for illuminance and 2 view points of luminance were monitored in every 30 minutes from 12:00 to 15:00. For the detailed analysis, photometric sensors of each room were installed at work-plane (8 points), wall (7 points), ceiling (3points), and exterior horizontal illuminance (1 point). Luminance of window, rare of the room was measured under clear sky. It is to be monitored by Agilent data logger, photometric sensor Li-cor and the Radiant Imaging ProMetric 1400. Comparisons with a light factor, increase-decrease ratio, uniformity, and luminance are discussed.