• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.115-115
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• 2010

광 결정 발광 다이오드를 제작하는데 있어서 문제가 되는, 표면 비 발광 재결합을 줄이기 위해서 $(NH_4)_2S_x$ 패시베이션 효과를 연구하였고, 실제 소자를 공정하였다. $(NH_4)_2S_x$ 패시베이션의 영향을 알아보기 위해서, GaAs 기판위에 10쌍 다중 양자 우물 구조를 가진, 에피탁시를 이용하여 광 결정 다이오드를 제작하였고, 그 후 패시베이션 처리를 하였다. 광 결정 격자 상수는 600 nm 였고, 전자 빔 노광기법을 이용하여 패턴을 만들었다. 패시베이션효과는 시분해 발광 측정을 이용하여 캐리어 라이프 타임의 변화를 통해 확인 할 수 있었다. 광 결정 구조가 없는 발광 다이오드에서의 라이프 타임은 2206 ps였고, 광 결정 구조를 가진 발광다이오드에서의 라이프타임은 831ps였다. 이는 식각된 구멍의 표면에서 비 발광 재결합이 증가했다는 것을 의미한다. 패시베이션 처리된 광 결정 발광다이오드의 라이프 타임은 1560 ps 으로 광 결정 구조의 표면에서 발생된 비 발광 표면 재결합이 상당히 줄었음을 알 수 있다. 상용 에피탁시에 실제 소자에 적용 가능한 광 결정 발광 다이오드를 제작하였다. 상용 에피탁시는 20쌍의 다중 양자우물과, 16쌍의 Distributed Bragg Reflector를 가진 구조이다. 이 상용 에피탁시에 광 결정 구조를 만들기 위해서 니켈 크롬 (NiCr) 마스크를 사용하였고, 기존 식각 시간보다 세배 길어진 식각 시간을 달성하였다.

• Journal of Game and Entertainment
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• v.2 no.2
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• pp.51-60
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• 2006

Recently, many streaming videos including drama, music videos, and movies have been extensively given on the web. Such video services are on negative lines in any service restriction depending on the age of users and then whole part of a video have been restricted considering the age of users. Therefore, in this paper, we will present a new method that provides the access depending on the ages of users and also sets the video rating of each scene in a video. To get this restricted access for video, we will first divide a streaming video into many scenes using histogram techniques. Each scene gets an access control depending on the nudity level. Finally, we will make the video indexing including the access level depending on its nudity level and then hide restricted scenes using several masks in playing that streaming video.

• Journal of Korea Multimedia Society
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• v.25 no.5
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• pp.685-694
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• 2022

The goal of few-shot semantic segmentation is to build a network that quickly adapts to novel classes with extreme data shortage regimes. Most existing few-shot segmentation methods leverage single or multiple prototypes from extracted support features. Although there have been promising results for natural images, these methods are not directly applicable to the aerial image domain. A key factor in few-shot segmentation on aerial images is to effectively exploit information that is robust against extreme changes in background and object scales. In this paper, we propose a Mask-Guided Attention module to extract more comprehensive support features for few-shot segmentation in aerial images. Taking advantage of the support ground-truth masks, the area correlated to the foreground object is highlighted and enables the support encoder to extract comprehensive support features with contextual information. To facilitate reproducible studies of the task of few-shot semantic segmentation in aerial images, we further present the few-shot segmentation benchmark iSAID-, which is constructed from a large-scale iSAID dataset. Extensive experimental results including comparisons with the state-of-the-art methods and ablation studies demonstrate the effectiveness of the proposed method.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.1012-1015
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• 2021

Covid-19 로 인한 마스크 착용이 청각장애인들의 소통을 더 어렵게 하는 바, 제 3 자의 도움 없이 쌍방향 소통을 가능하게 하는 서비스의 필요성이 커지고 있다. 이에 본 논문은 소통의 어려움을 겪는 청각장애인과 비청각장애인을 위한 쌍방향 소통 서비스에 대한 연구와 개발 과정, 기대 효과를 담는다. 서비스는 GRU-CNN 하이브리드 아키텍처를 사용하여 데이터셋을 영상 공간 정보와 시간 정보를 포함한 프레임으로 분할하는 영상 분류 기법과 같은 딥 러닝 알고리즘을 통해 수어 영상을 분류한다. 해당 연구는 "눈속말" 모바일 어플리케이션으로 제작 중이며 음성을 인식하여 수어영상과 텍스트로 번역결과를 제공하는 청각장애인 버전과 카메라를 통해 들어온 수어 영상을 텍스트로 변환하여 음성과 함께 제공하는 비청각장애인 버전 두 가지로 나누어 구현한다. 청각장애인과 비장애인의 쌍방향 소통을 위한 서비스는 청각장애인이 사회로 나아가기 위한 가장 기본적인 관문으로서의 역할을 할 것이며 사회 참여를 돕고 소통이라는 장벽을 넘어서는 발돋움이 될 것이라 예측된다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2022.07a
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• pp.49-52
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• 2022

건물 외벽에 발생하는 균열은 시설물 구조 안전에 영향을 미치며 그 크기에 따라 위험도가 달라진다. 이에 따라 전문검사관의 현장 점검을 통해 발생 균열 두께를 정밀하게 측정할 필요가 있고 최근에는 이러한 현장 안전점검에 인공지능을 도입하려는 추세다. 그러나 기존의 균열 데이터셋은 주로 콘크리트에만 한정되어 다양한 외벽에 강인한 모델을 구축하기 어렵고 균열 두께를 측정하기 위해 정확한 마스크(Mask) 정보가 필요하나 이를 만족하는 데이터셋이 부재하다. 본 논문에서는 다양한 외벽에 강인한 균열 구획화 모델을 목적으로 2,744장의 이미지를 촬영하고 매직 완드 기법으로 라벨링을 진행해 데이터셋을 구축 후, 이를 바탕으로 딥러닝 기반 균열 구획화 모델을 개발했다. UNet-ResNet50을 최종모델로 선정 및 개발 결과, 테스트 데이터셋에 대해 81.22%의 class IoU 성능을 보였다. 본 연구의 기술을 바탕으로 균열 두께를 측정하여 건축물 안전점검에 활용될 수 있기를 기대한다.

• The Journal of the Acoustical Society of Korea
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• v.27 no.8
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• pp.418-426
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• 2008

In this paper, we propose an algorithm for the frequency channel segmentation using peaks and valleys in spectrogram. The frequency channel segments means that local groups of channels in frequency domain that could be arisen from the same sound source. The proposed algorithm is based on the smoothed spectrum of the input sound. Peaks and valleys in the smoothed spectrum are used to determine centers and boundaries of segments, respectively. To evaluate a suitableness of the proposed segmentation algorithm before that the grouping stage is applied, we compare the synthesized results using ideal mask with that of proposed algorithm. Simulations are performed with mixed speech signals with narrow band noises, wide band noises and other speech signals.

• The Journal of the Korea Contents Association
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• v.9 no.12
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• pp.86-93
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• 2009

In this paper, we propose a method that generates a sketch likely to be drawn by a human from a real image(a computer generated image or a photo image). The method can create human friendly images with pen strokes by using image processing techniques such as spatial filters. In order to create the human friendly image, first, we made the tiny unnecessary contours. Second, we made the second image by inverting the first image and performed a processing similar to the first processing. Last, we subtracted the second image from the first image and added a hatch to it. The sequence of processing enables us to generate a human friendly image with line shading, likely to be sketched by water pen compared to the past method(pencil hatching and sketch effects). Also the proposed method can represent the sketch effects more effectively with applying different hatch to the shading area of a input image.

• Journal of KIISE
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• v.42 no.10
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• pp.1222-1230
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• 2015

Segmentation of the anterior cruciate ligament (ACL) in knee MRI remains a challenging task due to its inhomogeneous signal intensity and low contrast with surrounding soft tissues. In this paper, we propose a multi-atlas-based segmentation of the ACL in knee MRI with locally-aligned probabilistic atlas (PA) in an iterative graph cuts framework. First, a novel PA generation method is proposed with global and local multi-atlas alignment by means of rigid registration. Second, with the generated PA, segmentation of the ACL is performed by maximum-aposteriori (MAP) estimation and then by graph cuts. Third, refinement of ACL segmentation is performed by improving shape prior through mask-based PA generation and iterative graph cuts. Experiments were performed with a Dice similarity coefficients of 75.0%, an average surface distance of 1.7 pixels, and a root mean squared distance of 2.7 pixels, which increased accuracy by 12.8%, 22.7%, and 22.9%, respectively, from the graph cuts with patient-specific shape constraints.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11C
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• pp.1098-1107
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• 2005

The emerging H.264/AVC video coding standard improves coding performance significantly by adopting many advanced techniques. This is achieved at the expense of great increasing encoder complexity. Specifically the intra prediction using RDO examines all possible combinations of coding modes, which depend on spatial directional correlation with adjacent blocks. For 4${\times}$4 luma blocks, there are 9 modes, and for 16${\times}$16 luma and 8${\times}$8 chroma blocks, there are 4 modes, respectively. Therefore the number of mode combinations for each macroblock is 592. This paper presents a method to reduce the RDO complexity using simple directional masks and neighboring modes. According to the proposed method, we reduce the number of mode combinations to 132 at the most. Experimental results show the proposed method reduces the encoding time up to $70\%$ with negligible loss of PSNR and bitrate increase compared to the H.264/AVC exhaustive search.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.4
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• pp.327-334
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• 2006

The aerial photos need in a simple object such as cartography and ground cover classification and also in a social objects such as the city plan, environment, disaster, transportation etc. However, the shadow, which includes when taking the aerial photos, makes a trouble to interpret the ground information, and also users, who need the photos in their field tasks, have a restriction. Generally the shadow occurs by the building and surface topography, and the detail cause is by changing of the illumination in an area. For removing the shadow this study uses the single image and processes the image without the source of image and taking situation. Also, applying the entropy minimization method it generates the 1-D gray-scale invariant image for creating the shadow edge mask and using the Canny edge detection creates the shadow edge mask, and finally by filtering in Fourier frequency domain creates the intrinsic image which recovers the 3-D color information and removes the shadow.