• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.173-173
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• 2010

We proposed viewing angle switchable liquid crystal display(LCD) associated with fringe-field switching (FFS) mode with high aperture ratio characteristic. In the device, single pixel is separated into two regions, named as main pixel for displaying images and sub pixel for viewing angle control. In sub pixel region, add the common electrode on the top substrate and the initial alignment of liquid crystal is Hybrid Alignment Nematic (HAN) state. In conclusion, we suggested that the device has high aperture ratio characteristic because the LC directors are rotated in which viewing angle control region are generated fringe electric field.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.502-504
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• 2009

We demonstrate a pixel-isolated bistable twist-splay namatic (PI-BTSN) liquid crystal (LC) cell which has two stable states of splay and ${\pi}$-twist. Each state is stabilized by a multi-dimensional anchoring effect of pixel-isolating polymer walls without any chiral additives. Polymer walls are formed around the pixel region by anisotropic phase separation between LCs and reactive mesogens. Switching between the two states is archived by using vertical and horizontal electric fields. The memory mode of the fabricated LC cell has shown infinity memory time.

• Journal of the Semiconductor & Display Technology
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• v.18 no.3
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• pp.1-6
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• 2019

Foreground/background segmentation in video sequences is often one of the first tasks in machine vision applications, making it a critical part of the system. In this paper, we present an improved sample-based technique that provides robust background image as well as segmentation mask. The conventional multiple interval sampling (MIS) algorithm have suffer from the unbalance of computation time per frame and the rapid change of confidence factor of background pixel. To balance the computation amount, a random-based pixel update scheme is proposed and a spatial and temporal smoothing technique is adopted to increase reliability of the confidence factor. The proposed method allows the sampling queue to have more dispersed data in time and space, and provides more continuous and reliable confidence factor. Experimental results revealed that our method works well to estimate stable background image and the foreground mask.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.05a
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• pp.463-466
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• 2005

While recent display devices are becoming light and slim, the size of a screen is especially the important issue in the field of display devices. Furthermore, it is also required that the projection TV, a large screen display device, be able to represent higher resolutions as the digital broadcasting is set off. In order to realize high resolutions in a DLP projection TV, the number of pixel on DMD should be increased. However, a large number of pixels make it difficult to realize resulting small sized pixels and this cause the increase in cost. Therefore, we propose a simple and improved pixel enhancement actuator using the existing DMD by offsetting half pixels repeatedly in the vertical direction.

• Journal of Korea Multimedia Society
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• v.18 no.3
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• pp.312-322
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• 2015

In this paper a new defect detection method for flat panel display that does not require any separately prepared reference images and shows robustness against problems with regard to pixel tolerance and nonuniform illumination condition is proposed. In order to perform defect detection under any magnification value of camera, the proposed method automatically obtains the value of pattern interval through an image analysis. Using the information for pattern interval, an advanced PCSR-G method presented in this paper utilizes neighboring patterns as its reference images instead of utilizing any separately prepared reference images. Also this paper proposes a scheme to improve the performance of the conventional PCSR-G method by extracting and applying additional information for pixel tolerance and intensity distribution considering the value of pattern interval. Simulation results show that the performance of the proposed method utilizing pixel tolerance and intensity distribution is superior to that of the conventional method. Also, it is proved that the proposed method that is implemented using parallel technique based on GPGPU can be applied to real system.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.15 no.3
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• pp.205-210
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• 2022

A novel OLED pixel circuit is proposed in this paper that uses only n-type thin-film transistors(TFTs) to improve the luminance non-uniformity of the AMOLED display caused by the threshold voltage variation of an OLED driving TFT. The proposed OLED pixel circuit is composed of 6 n-channel TFTs and 2 capacitors. The operation of the proposed OLED pixel circuit consists of the capacitor initializing period, threshold voltage sensing period of an OLED·driving TFT, image data voltage writing period, and OLED·emitting period. As a result of SmartSpice simulation, when the threshold voltage of·OLED·driving TFT varies from 1.2 V to 1.8 V, the proposed OLED pixel circuit has a maximum current error of 5.18 % at IOLED = 1 nA. And, when the OLED cathode voltage rises by 0.1 V, the proposed OLED pixel circuit has very little change in the OLED current compared to the conventional OLED pixel circuit. Therefore, the proposed pixel circuit exhibits superior compensation characteristics for the threshold voltage variation of an OLED driving TFT and the rise of the OLED cathode voltage compared to the conventional OLED pixel circuit.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1267-1270
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• 2006

Organic light-emitting diode (OLED) display panel with $64\;{\times}\;64$ pixels utilizing the charge-pump (CP) pixel addressing method was fabricated using conventional thin-film processes. Each pixel consists of a-Si:H Schottky diode and $ITO/SiO_2/ITO$ capacitor. It is shown that CP-OLED is technically feasible for information display and a driving voltage below $4V_{pp}$ is enough for nominal operation.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.850-853
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• 2009

Many well-known pixel compensation circuits have been applied to control TFT $V_{th}$ variations on small size AMOLED panels. For large (>30-inch) AMOLEDs, luminance and color uniformity are affected by TFT variations, but also by ELVDD IR drop and cavity non-uniformity which are not easily compensated by in-pixel circuits. AMOLED panels may also suffer from manufacturing-induced mura. An external compensation method based on optical measurements is proposed and applied to large AMOLED panels. It improves luminance uniformity by up to 95% at 200nits and color uniformity by up to 99% (${\Delta}$u'v' <0.004) on large AMOLED panels, and provides-increased margin against processinduced mura.

• Journal of the Semiconductor & Display Technology
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• v.9 no.2
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• pp.87-90
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• 2010

A new SRAM pixel circuit with RESET Transistor of a LCOS display module was designed for a pico-projector application. A dual-block PWM method was also proposed to realize the field sequential color system having only one LCOS panel. 0.29 inch LCOS panel in SVGA resolution was fabricated and the proposed dual-block PWM method was tested with it. Discontinuity of brightness curve was caused due to multi-pulses and it was improved by the adoption of proper mapping table. With the proposed SRAM with RESET pixel circuit and dual-block PWM method, the test images were successfully demonstrated.

• 한국정보디스플레이학회:학술대회논문집
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• 2004.08a
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• pp.749-752
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• 2004

Unlike OLEDs, there is no lifetime testing procedure for TFTs. In this work, we have defined such a procedure and developed a method for the accelerated stress testing of TFT pixel circuits in a-Si AMOLED displays. The acceleration factors derived are based on high current and temperature stress, and can be used to significantly reduce the testing time required to guarantee a 20000-hour display backplane lifespan.