• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.84-89
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• 2021

Indium tin oxide (ITO) transparent electrodes, which are used to manufacture organic light-emitting diodes, are used in light-emitting surface electrodes of display EL panels such as cell phones and TVs, liquid crystal panels, transparent switches, and plane heating elements. ITO is a major component that consists of indium and tin and is advantageous in terms of obtaining sheet resistance and light transmittance in a thin film. However, the optical performance of devices decreases with an increase in its thickness. A digital holography system was constructed and measured for the step measurement of the ITO thin film, and the reliability of the technique was verified by comparing the FE-SEM measurement results. The error rate of the step difference measurement was within ±5%. This result demonstrated that this technique is useful for applications in advanced MEMS and NEMS industrial fields.

• Transactions on Electrical and Electronic Materials
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• v.13 no.6
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• pp.310-316
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• 2012

A new method for early caries diagnosis was proposed and tested through a home-made optical examination system that used quantitative light fluorescence (QLF) and digital imaging fiber optic transillumination (FOTI) (DIFOTI), with light sources across a wide spectral range, from 350 nm to 1,000 nm. The front-illuminated infrared light scattering image (FIR) showed similar diagnostic abilities to that of DIFOTI. The FIR method was invented based on the observation that caries lesions lose the high transmittance and low scattering properties of benign enamel tissue. There are various methods for the early diagnosis of caries, such as visual examination, exploration, X-ray radiography, QLF, FOTI, and infrared fluorescence (diagnodent). Among them, methods based on optical properties are regarded as having the most potential. A comparative study was performed between the FOTI, QLF, diagnodent, optical coherence tomography, and FIR scattering image methods, using 20 extracted teeth samples with early caries. A scale of lesion measurement based on optical image contrast was proposed. The statistical analysis showed a significant correlation between the DIFOTI and FIR methods (r = 0.35, p < 0.05). However, the QLF and diagnodent methods showed little association with FIR images, as they have different detection principles as compared with FIR. Tomographic images obtained by OCT, using 1,330 nm super luminescent LED as a gold standard of tooth structure, verified that the FOTI and FIR results correctly represented the lack of homogeneity in dental tissue. The newly proposed FIR method attained similar diagnostic results to those of FOTI, but with an easier approach.

• Journal of Intelligence and Information Systems
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• v.29 no.2
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• pp.115-127
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• 2023

Video stabilization is one of the camera technologies that the importance is gradually increasing as the personal media market has recently become huge. For deep learning-based video stabilization, existing methods collect pairs of video datas before and after stabilization, but it takes a lot of time and effort to create synchronized datas. Recently, to solve this problem, unsupervised learning method using only unstable video data has been proposed. In this paper, we propose a network structure that learns the stabilized trajectory only with the unstable video image without the pair of unstable and stable video pair using the Convolutional Auto Encoder structure, one of the unsupervised learning methods. Optical flow data is used as network input and output, and optical flow data was mapped into grid units to simplify the network and minimize noise. In addition, to generate a stabilized trajectory with an unsupervised learning method, we define the loss function that smoothing the input optical flow data. And through comparison of the results, we confirmed that the network is learned as intended by the loss function.

• Korean Journal of Optics and Photonics
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• v.22 no.5
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• pp.230-238
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• 2011

There are many types of interchangeable zoom lens in the digital single lens reflex camera and the compact digital still camera system in order to meet various specifications such as the field angle. Thus special cases for which the focus adjustment using only an auto-focus group is not available in the focal point correction (that is, the focus adjustment) of both wide and tele-zoom positions are sometimes generated. In order to make each BFL(back focal length, BFL) coincide at wide and tele-zoom positions with each designed BFL, focus adjustment processes must be performed at least in these two points within the zoom lens system. In this paper, we propose a method of focus adjustment by using the concept of focus sensitivity, and we calculate a limit on focus adjustment distance by means of statistical analysis.

• Korean Journal of Optics and Photonics
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• v.21 no.3
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• pp.91-96
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• 2010

The size of a reconstructed image depends on the reconstruction distance and wavelength. The double fourier transform method is proposed to eliminate the dependence on the reconstruction distance and wavelength. We can get a fixed reconstructed image size by using the double fourier transform method. Two wavelength digital holography is proposed to measure the step height, which is larger than a single wavelength. The two image size of different wavelength holograms should be the same in order to apply two wavelength digital holography. We use two wavelength digital holography and double fourier transforms to measure the step height. The measured data were reasonable and we found that the double fourier transform is useful in two wavelength digital holography.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.43 no.3 s.309
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• pp.25-30
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• 2006

An infrared imaging method is proposed in which direct measurement of the spectral response of CCD sensors can be achieved through digital image processing. This method allows for a simple and economic method to detect the spectral sensitivity of commercialized CCD sensors. The key components of the apparatus are a monochromator, CCD-sample supporter and a personal computer equipped with a digital image processing systems. Tentative experimentation conducted on the commercialized CCD camera has resulted in a fairly consistent agreement with the theoretical model.

• Journal of the Korea Computer Graphics Society
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• v.18 no.1
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• pp.23-28
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• 2012

In this paper, we present a new method for automatically synchronize captured facial expression data with its corresponding motion data. In a usual optical motion capture set-up, a detailed facial expression can not be captured simultaneously in the motion capture session because its resolution requirement is higher than that of the motion capture. Therefore, those are captured in two separate sessions and need to be synchronized in the post-process to be used for generating a convincing character animation. Based on the patterns of the actor's neck movement extracted from those two data, we present a non-linear time warping method for the automatic synchronization. We justify our method with the actual examples to show the viability of the method.

• Korean Journal of Optics and Photonics
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• v.20 no.3
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• pp.156-165
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• 2009

We theoretically derive the set of general paraxial zoom locus equations for all zoom lens systems with finite object distance, including the infinite object distance case, by using the Gaussian bracket method and matrix representation of paraxial ray tracing. We make the zoom locus program by means of a numerical calculation method according to these equations in Visual Basic Language. Consequently, the solutions of this method can be consistently and flexibly used in all types of zoom lens in the step of initial design about zoom loci. Finally, in order to verify the justification and usefulness of this method, we show that two examples, such as $M_{4a}$ and $M_{4h}$ types of 4 groups, and one example, $M_{5n}$ type of 5 groups, which are very complicated zoom lens systems, can be rapidly and diversely traced through various interpolations by using this program.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.11B
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• pp.1903-1908
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• 2000

사다리형 디지털필터는 일반적으로 IIR 필터의 직접형, 병렬형 또는 종속형과 비교하여 주파수응답 감도가 뛰어나기 때문에 최근 많이 이용되고 있다. 사다리형 디지털필터는 모델의 형식에 따라 연분수 전개가 다르고 주어지는 전달함수에 따라 실현 가능한 형식과 불가능한 형식이 있다. 본 논문에서는 연분수 형태의 제 III 사다리형 디지털필터를 모델로 하여 방형성 결합기와 광섬유를 이용한 사다리형 광섬유필터의 실현조건과 설계방법을 논하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.415-417
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• 2015

대기오염방지를 위해서는 배출되는 대기오염물질을 측정하고 이를 관리하여 대기오염을 신속히 파악하고 사전에 방지하기 위한 서비스가 필요하다. 본 논문에서는 광학센싱을 이용해 굴뚝연기의 혼탁도를 측정하고 이를 웹과 모바일 기기에서 측정결과를 실시간으로 검색할 수 있는 웹+모바일 시스템을 설계하고 구현한다. 구현된 시스템은 모바일 운영체제에 독립적인 웹앱의 형태로 제공되어 사용자의 다양한 모바일 기기에서 운영될 수 있으며 PC환경의 웹에 내장되어 통합되어져 시스템의 유지보수가 쉽다는 장점이 있다.