• Current Optics and Photonics
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• 제4권3호
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• pp.193-199
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• 2020

In this paper we propose a dark-field digital holographic microscopy system based on 360-degree oblique illumination. This setup is constructed without using a dark-field objective. The principle of 360-degree oblique illumination of vortex beam and dark-field digital holographic microscopy are introduced theoretically and experimentally. By analyzing the reconstructed image of a dark-field digital hologram of a USAF 1951 target, it is proved that the imaging resolution can be improved by this method. And also, comparison and analysis are made on the reconstructed image of a bright-dark field digital hologram of a pumpkin stem slice, the result shows that the imaging contrast is also enhanced with this method, and it is effective for dark-field digital holographic microscopy imaging of large transparent biological samples.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.984-987
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• 2003

유기발광소자 안에 존재하는 비발광영역(dark spot)의 전압에 대한 영향을 근접장 마이크로파 현미경(near-field scanning microwave microscope)을 이용하여 관찰하였다. 유기발광소자는 glass/indiumtin oxide(ITO)/Cu-Pc/tris-(8-hydroquinoline)aluminum(Alq3)/aluminum(Al) 의 기본구조로 제작하였다. Dark spot은 ITO 기판을 부분적으로 에칭하여서 형성시켰다. Dark spot에 $0{\sim}l5 V$ 까지 전압을 인가시키면서 인가 전압에 따른 전기적 특성을 근접장 마이크로파 현미경 image의 변화와 반사계수인 $S_{11}$ 측정을 통하여 연구하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 디스플레이 광소자분야
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• pp.147-150
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• 2003

유기발광소자 안에 존재하는 비발광영역(dark spot)의 전압에 대한 영향을 근접장 마이크로파 현미경(near-field scanning microwave microscope)을 이용하여 관찰하였다. 유기발광소자는 glass/indiumtin oxide(ITO)/Cu-Pc/tris-(8-hydroquinoline)aluminum(Alp3)/aluminum(Al)의 기본구조로 제작하였다. 비발광영역은 ITO 기판을 부분적으로 에칭하여서 형성시켰다. Dark spot에 0~15V 전압을 인가시키면서 인가 전압에 따른 dark spot 구조적 및 전기적 특성을 근접장 마이크로파 현미경 Image의 변화와 반사계수인 $S_11$측정을 통하여 연구하였다.

• 전자공학회논문지
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• 제51권1호
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• pp.145-151
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• 2014

본 논문에서는 한 장의 영상에서 안개를 제거하는 알고리즘을 제안한다. 기존의 Dark Channel Prior(DCP) 알고리즘은 영상의 어두운 정보를 계산하여 전달량을 추정한 후, 매팅(matting) 기법을 사용하여 안개 영역을 보완하여 검출한다. 이 과정에서 블록현상이 발생하는 문제가 있으며 이로 인해 안개를 효율적으로 제거하는데 한계점이 있다. 이 문제를 해결하기 위해 본 논문에서는 Hidden Markov Random Field(HMRF) 와 Expectation-Maximization(EM) 알고리즘을 이용하여 매팅 과정에서 발생하는 블록문제를 해결하고자 하였다. 실험 결과를 통하여 제안한 방법은 기존 방법보다 안개제거에서 더 향상된 결과를 얻을 수 있음을 확인하였다.

• Applied Microscopy
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• 제45권1호
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• pp.23-31
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• 2015

Dark field (DF) transmission electron microscopy image has become a popular characterization method for two-dimensional material, graphene, since it can visualize grain structure and multilayer islands, and further provide structural information such as crystal orientation relations, defects, etc. unlike other imaging tools. Here we present microstructure of graphene, particularly, using DF imaging. High-angle grain boundary formation wass observed in heat-treated chemical vapor deposition-grown graphene on the Si substrate using patch-quilted DF imaging processing, which is supposed to occur by strain around multilayer islands. Upon the crystal orientation between layers the multilayer islands were categorized into the oriented one and the twisted one, and their local structure were compared. In addition information from each diffraction spot in selected area diffraction pattern was summarized.

• Applied Microscopy
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• 제41권3호
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• pp.215-222
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• 2011

We discuss the experimental procedure for extracting reliable phase information from a defocus series of transmission electron microscopy (TEM) dark-field images using the transport of intensity equation (TIE). Taking InGaN/GaN multi-quantum well light-emitting diode as a model system, various factors affecting the final result of reconstructed phase such as TEM sample preparation, TEM imaging condition, image alignment, the correction of defocus values and the use of high frequency pass filter are evaluated. The obtained phase of wave function was converted to the geometric phase of the corresponding lattice planes, which was then used for the two-dimensional mapping of lattice strain following the dark-field inline holography (DIH) routine. The strain map obtained by DIH after optimized image processing is compared with that obtained by the geometric phase analysis of high resolution TEM (HRTEM) image, manifesting that DIH yields more accurate and reliable strain information than HRTEM-based GPA.

• 한국분말재료학회지
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• 제24권4호
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• pp.285-291
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• 2017

We propose a custom analysis technique for the dark field (DF) image based on transmission electron microscopy (TEM). The custom analysis technique is developed based on the $DigitalMicrograph^{(R)}$ (DM) script language embedded in the Gatan digital microscopy software, which is used as the operational software for most TEM instruments. The developed software automatically scans an electron beam across a TEM sample and records a series of electron diffraction patterns. The recorded electron diffraction patterns provide DF and ADF images based on digital image processing. An experimental electron diffraction pattern is recorded from a IrMn polycrystal consisting of fine nanograins in order to test the proposed software. We demonstrate that the developed image processing technique well resolves nanograins of ~ 5 nm in diameter.

• 한국안전학회지
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• 제23권6호
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• pp.164-170
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• 2008

This research was verified detection way of intercept vehicles and performance evaluation after system installation using image detector as detection way of ground installation. By image recognition algorithm was on the trace of moving orbit of violation vehicles for detection way of intercept vehicles. When moving orbit is located special site, utilized geometric image calibration and DC-notch filter. These are cognitive system of license plate by making signal. Then, Bright Evidence Detection and Dark Evidence Detection were applied to after mixing. It is applied to way of Backward tracking for detection way of intercept vehicles. After the field evaluation of developed system, it should be analyzed the more high than recognition rate of minimum standards 80%. It should rise in the estimation of the site applicability is highly from now.

• 한국산업융합학회 논문집
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• 제4권1호
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• pp.27-34
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• 2001

Refining of powder particles and their dissolution into the Al matrix during mechanical alloying(MA) were investigated by using X-ray diffraction(XRD) transmission electron microscopy (TEM) functions of alloy composition, milling time and ball to powder ratio(BPR). It is found that Ti particles less than 20nm are observed in a dark field image of mechanically alloyed Al-10wt%Ti whose XHD pattern exhibits no Ti peak. The observed change of lattice constant of AI indicates that about 1 wt%Ti can he solved in Al after MA for a long time, independent of alloy composition, milling time and BPR, suggesting that most of Ti particles arc retained in the Al matrix. It is concluded that the disappearance of XRD peaks in mechanically alloyed Al-10wt%Ti is not simply attributable to the dissolution of Ti into Al, but associated mainly with extreme refining and/or heavy straining of Ti Particles.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권1호
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• pp.341-363
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• 2016

Haze or fog is a common natural phenomenon. In foggy weather, the captured pictures are difficult to be applied to computer vision system, such as road traffic detection, target tracking, etc. Therefore, the image dehazing technique has become a hotspot in the field of image processing. This paper presents an overview of the existing achievements on the image dehazing technique. The intent of this paper is not to review all the relevant works that have appeared in the literature, but rather to focus on two main works, that is, image dehazing scheme based on atmospheric veil and image dehazing scheme based on dark channel prior. After the overview and a comparative study, we propose an improved image dehazing method, which is based on two image dehazing schemes mentioned above. Our image dehazing method can obtain the fog-free images by proposing a more desirable atmospheric veil and estimating atmospheric light more accurately. In addition, we adjust the transmission of the sky regions and conduct tone mapping for the obtained images. Compared with other state of the art algorithms, experiment results show that images recovered by our algorithm are clearer and more natural, especially at distant scene and places where scene depth jumps abruptly.