• Journal of the Optical Society of Korea
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• 제17권5호
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• pp.392-398
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• 2013

As the essential techniques for the CD (Critical Dimension) measurement of the LCD pattern, there are various modules such as an optics design, auto-focus [1-4], and precise edge detection. Since the operation of image enhancement to improve the CD measurement repeatability, a ring type of the reflected lighting optics is devised. It has a simpler structure than the transmission light optics, but it delivers the same output. The edge detection is the most essential function of the CD measurements. The CD measurement is a vital inspection for LCDs [5-6] and semiconductors [7-8] to improve the production yield rate, there are numbers of techniques to measure the CD. So in this study, a new subpixel algorithm is developed through facet modeling, which complements the previous sub-pixel edge detection algorithm. Currently this CD measurement system is being used in LCD manufacturing systems for repeatability of less than 30 nm.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 학술대회 및 기술세미나 논문집 디스플레이 광소자
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• pp.43-44
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• 2006

We have studied effect of Patterned Vertical Alignment (PVA) mode on electro-optical characteristics and stability of liquid crystal director upon electrode pattering. In the present studies, LC director field and stability of conventional PVA mode electrode patterns were analyzed and new type of electrode patterns were suggested. At last, comparison between this new type of electrode patterns to conventional electrode pattern types were followed.

• 한국전기전자재료학회논문지
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• 제22권2호
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• pp.119-122
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• 2009

As infrared light radiates, the CMOS Readout IC (ROIC) for the microbolometer typed infrared sensor detects voltage or current which is caused by the variation of resistance in the bolometer sensor. A serious problem we may have in designing the ROIC is the value of bolometer and reference resistors will be changed due to process variation. Since each pixel does not have the same value of resistance, fixed pattern noise problems happen during the sensor operations. In this paper, we propose a novel technique to compensate the fluctuation of reference resistance with taking account of process variation. By using a comparator and a cross coupled latch, we will make the value of reference resistor same as the bolometer's.

• Journal of the Optical Society of Korea
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• 제5권3호
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• pp.93-98
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• 2001

In order to verify the performance of the two-stage iterative Fourier transform algorithm[Hankook Kwanghak Hoeji 11, 47 (2000)], a number of phase-only diffractive pattern elements which produce simple 16x16-pixel intensity patterns useful in the field of optical information processing have been designed and their performance has been compared with that from the nonlinear least-squares algorithm[Appl. Opt. 36, 7297(1977)] which is computationally intensive. for all intensity patterns, elements designed by the former algorithm show better overall signal-to noise ratio and uniformity, although they show essentially the same diffraction efficiency. In the case of continuous phase elements, they show far superior uniformity. Computationally,. the former algorithm is far more efficient than the latter.

• 한국멀티미디어학회논문지
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• 제7권3호
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• pp.327-339
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• 2004

본 논문에서는 반복적인 에러 최소화 기법을 이용한 하프톤 영상의 워터마킹 알고리즘을 제안하였다. 워터마크는 하프톤 영상의 랜덤한 위치의 픽셀값으로 저장된다. 삽입된 워터마크로 인한 하프톤 영상의 왜곡을 최소화하고 비가시성을 증대하기 위하여 반복적인 에러 최소화 기법이 사용된다. 원영상과 HVS(Human Visual System) 필터 처리된 하프톤 영상과의 차이를 하프토닝 에러로 정의하고 반복적으로 각각의 픽셀 위치에서 이 하프토닝 에러를 최소화할 수 있는 픽셀 패턴을 찾아서 이것으로 원래의 픽셀패턴을 대치한다. 절단이나 회전과 같은 기하학적인 변형에 견고하게 하기 위하여 동일한 워터마크를 반복하여 하프톤 영상안에 삽입하였다. 실제 인쇄 및 스캐닝 실험을 통하여 제안된 알고리즘이 기하학적 변형에 견고함을 보였고 또한 기존과 방법과 비교하여 제안된 방법이 많은 양의 워터마크 정보에도 불구하고 우수한 품질의 하프톤 영상을 생성함을 보였다.

• 대한기계학회논문집
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• 제12권5호
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• pp.1121-1129
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• 1988

본 연구에서는 oil-bath를 이용한 종래의 방법에 의해 얻어진 사진으로 부터 분무액적의 수와 크기를 자동적으로 측정하는 방법을 시도하였다.특히 측정을 효과 적으로 수행하기 위해 한 영상에서 비교적 맣은 분무액적을 측정하는 방법과 붙어있는 액적들이나 이물질 등을 걸러내는데 중점을 두었으며, 아울러 본 연구를 통하여 설정 된 측정방법의 정확도를 검토하였다.

• 센서학회지
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• 제29권1호
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• pp.27-32
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• 2020

This study proposes a pixel-patterning method for organic light-emitting diodes (OLEDs) based on thermal transfer. An infrared lamp was introduced as a heat source, and glass type donor element, which absorbs infrared and generates heat and then transfers the organic layer to the substrate, was designed to selectively sublimate the organic material. A 200 nm-thick layer of molybdenum (Mo) was used as the lightto-heat conversion (LTHC) layer, and a 300 nm-thick layer of patterned silicon dioxide (SiO₂), featuring a low heat-transfer coefficient, was formed on top of the LTHC layer to selectively block heat transfer. To prevent the thermal oxidation and diffusion of the LTHC material, a 100 nm-thick layer of silicon nitride (SiN_x) was coated on the material. The fabricated donor glass exhibited appropriate temperature-increment property until 249 ℃, which is enough to evaporate the organic materials. The alpha-step thickness profiler and X-ray reflection (XRR) analysis revealed that the thickness of the transferred film decreased with increase in film density. In the patterning test, we achieved a 100 ㎛-long line and dot pattern with a high transfer accuracy and a mean deviation of ± 4.49 ㎛. By using the thermal-transfer process, we also fabricated a red phosphorescent device to confirm that the emissive layer was transferred well without the separation of the host and the dopant owing to a difference in their evaporation temperatures. Consequently, its efficiency suffered a minor decline owing to the oxidation of the material caused by the poor vacuum pressure of the process chamber; however, it exhibited an identical color property.

• Journal of Biosystems Engineering
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• 제17권1호
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• pp.65-78
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• 1992

When using a computer vision system for a measurement, the geometrically distorted input image usually restricts the site and size of the measuring window. A geometrically distorted image caused by the image sensing and processing hardware degrades the accuracy of the visual measurement and prohibits the arbitrary selection of the measuring scope. Therefore, an image calibration is inevitable to improve the measuring accuracy. A calibration process is usually done via four steps such as measurement, modeling, parameter estimation, and compensation. In this paper, the efficient error calibration technique of a geometrically distorted input image was developed using a neural network. After calibrating a unit pixel, the distorted image was compensated by training CMLAN(Cerebellar Model Linear Associator Network) without modeling the behavior of any system element. The input/output training pairs for the network was obtained by processing the image of the devised sampled pattern. The generalization property of the network successfully compensates the distortion errors of the untrained arbitrary pixel points on the image space. The error convergence of the trained network with respect to the network control parameters were also presented. The compensated image through the network was then post processed using a simple DDA(Digital Differential Analyzer) to avoid the pixel disconnectivity. The compensation effect was verified using known sized geometric primitives. A way to extract directly a real scaled geometric quantity of the object from the 8-directional chain coding was also devised and coded. Since the developed calibration algorithm does not require any knowledge of modeling system elements and estimating parameters, it can be applied simply to any image processing system. Furthermore, it efficiently enhances the measurement accuracy and allows the arbitrary sizing and locating of the measuring window. The applied and developed algorithms were coded as a menu driven way using MS-C language Ver. 6.0, PC VISION PLUS library functions, and VGA graphic functions.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1244-1247
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• 2004

For obtaining the best panel quality of color filter on array(COA) architecture in TFF LCD, we investigated the influence of deposition temperature, $O_2$ flow, thickness on the optical transmittance, wet etching and adhesion properties of IZO deposited onto each color photo resist(red, green, blue). Average transmittance of the pixel single layer in the visible range(between 380 and 780nm) was mainly affected by thickness and showed maximum at 1250 ${\AA}$ while the thickness showing peak transparency in each R, G, B wavelength was different. The relation was calculated by using bi-layer transmission and reflectance model, which corresponded to experimental data very well. The adhesion of IZO deposited on each color PR was found to have enhanced value except red PR case, compared to that of IZO which was deposited on $SiN_x$. Wet etching pattern linearity was decreased as the thickness increased. The thickness of IZO was one of vital factors in order to optimize overall pixel process for fabricating COA structure.

• 한국정보통신학회논문지
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• 제13권5호
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• pp.937-943
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• 2009

본 논문에서는 영상 처리를 이용하여 차체의 진동에 영향을 미치는 자동차 T-Bar부품에서의 볼트와 너트의 존재 유무를 판별하는 알고리즘이 소개된다. T-Bar의 볼트와 너트 존재 유무를 판별하기 위하여 볼트와 너트의 특징치들이 학습되고 통계적 패턴매칭 방법을 이용하여 학습된 특징치들이 매칭된다. 또한 영상마다 볼트와 너트들의 화소값이 크게 변화하여 매칭율이 낮아지기 때문에 화소값의 최대와 최소 변화률이 이용된다. 본 논문에서 제안한 방법은 기존의 방법들에 비해 검사시간을 대폭 축소시켜 실시간이 요구되는 검사 자동화 분야에 아주 효율적이다.