• 인지과학
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• 제11권2호
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• pp.79-87
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• 2000

본 논문에서는 MPEG 압축 비디오 상에서 얼굴 영역을 추출하고 이를 인식하는 방법에 대하여 제안한다. 제안된 방법은 크게 MPEG 압축 비디오의 처리를 위한 축소된 DC 영상의 구성단계, 축소된 DC 영상에서의 얼굴 영역 추출 단계, 그리고 얼굴 영역이 추출된 프레임에 대한 압축 복원 및 얼굴 인식의 3단계로 구성되어 있다. DC 영상의 구성 단계에서는 압축 복원 없이 DCT 계수의 DC 값과 2개의 AC 값만을 사용하여 부분적인 2차원 역 DCT 변환을 이용한 방법을 사용하였으며, 얼굴 영역 추출 단계에서는 DC 영상에 대해 얼굴의 색상 및 형태 정보를 이용한 얼굴 후보 영역 추출 방법과 K-L 변환 및 역 변환의 오차에 의한 얼굴 영역 추출 방법을 사용하였다. 얼굴 인식 단계에서는 얼굴 영역이 추출된 프레임에 대하여 GOP 단위의 압축 복원을 수행한 후 고유 얼굴 영상을 이용한 방법으로 얼굴 인식을 수행하였다. 제안된 방법의 성능을 검증하기 위하여 뉴스와 드라마 MPEG 비디오를 대상으로 실험을 수행하였으며, 실험 결과 제안된 방법이 효율적임을 알 수 있었다.

• 디지털콘텐츠학회 논문지
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• 제17권5호
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• pp.433-439
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• 2016

본 논문에서는 기존의 데이터 은닉 기법들을 개선하는 스테가노그라피 방법을 제시한다. 이 방법은 이미지의 압축 도메인(JPEG)에서 동작한다. 현재 정보은닉 방법의 대부분은 일반적으로 정보를 숨길 계수를 변경한다. 그리고 몇 가지 방법은 매트릭스 인코딩을 포함하는 F5 같은 일반적인 스테가노그라피 방법의 성능을 향상시키기 위해 노력하였다. 이러한 논문들은 압축 도메인 계수에 데이터를 숨길 때 발생하는 왜곡을 감소시키는 목적을 달성하였다. 제안 논문에서는 압축 도메인에서 데이터를 숨기는 동안 양자화 테이블의 효과를 분석 하였다. 결과적으로, 스테가노그라피 기술의 적용에서 발생하는 왜곡을 양자화 테이블의 효율적 이용에 의해 감소시킬 수 있음을 알아냈다. 본 논문에서는 이미지 품질의 관점에서 일부(최대: 약 6.5%) 더 개선 된 결과를 제공한다. 제안한 논문에서 개발한 알고리즘은 JPEG 외의 압축영역 정보 은닉 기법들의 성능 개선에 도움을 줄 수 있다.

• 한국멀티미디어학회:학술대회논문집
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• 한국멀티미디어학회 2000년도 춘계학술발표논문집
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• pp.328-331
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• 2000

In this paper , we propose a texture feature extraction method of reduce the massive computational time on extracting texture, features of large sized medical such as MRI, CT-scan , and an index structure, called GLTFT, to speed up the retrieval performance. For these, the original image is transformed into a compressed image by Wavelet transform , and textural features such as contrast, energy, entropy, and homogeneity of the compressed image is extracted by using GLCM(Gray Level Co-occurrence Metrix) . The proposed index structure is organized by using the textural features. The processing in compressed domain can give the solution of storage space and the reduction of computational time of feature extracting . And , by GLTFT index structure, image retrieval performance can be expected to be improved by reducing the retrieval range . Our experiment on 270 MRIs as image database shows that shows that such expectation can be got.

• 소음진동
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• 제9권3호
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• pp.472-476
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• 1999

The effect of static preload on the dynamic properties of rubber materials is rather important, especially when good isolation characteristics are required at high frequencies. However, there are still few papers for dynamic characteristics of compressed rubber components. It was demonstrated in reference (4) that for bonded rubber material of a cylindrical shape, a simplified theory equation between linear dynamic and nonlinear static behavior of rubber material was useful to predict their combined effects. This paper presents the second part of the study. It is confirmed that for the compressed rubber material, the stress can be factored into a function of frequency and a function of strain(stretch). The finite element methodis applied to analyze non-linear large deformation of rubber material and its results are compared with those of a simplified theory equation. The predicted dynamic material properties based on non-linear static finite element analyses have a good agreement of experimental results and those based on simplified theory equation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권2호
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• pp.580-592
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• 2012

In this paper, a new compressive feedback (CF) scheme based on distributed compressed sensing (DCS) for time-corrected MIMO channel is proposed. First, the channel state information (CSI) is approximated by using a subspace matrix, then, the approximated CSI is compressed using a compressive matrix. At the base station, the approximated CSI can be robust recovered with simultaneous orthogonal matching pursuit (SOMP) algorithm by using forgone CSIs. Simulation results show our proposed DCS-CF method can improve the reliability of system without creating a large performance loss.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.287-294
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• 2002

CAES which is called as a compressed air energy storage was firstly developed at Huntorf, German in 1978. The capacity of that system was 290MW, and it can be treated as a first commercial power plant. CAES has a lot of merits, such as saving the unit price of power generation, averaging the peak demand, improvement of maintenance, enlarging the benefit of dynamic use. According to the literature survey, the unlined rock cavern should be proposed to be a reasonable storing style as a method of compressed air storage in Korea. We decided the hill of the Korea Institute of Geoscience and Mineral Resources as CAES site. If we construct the underground spaces in this site, the demand for electricity nearby Taejon should be considered. So we could determine the capacity of the power plant as a 350MW, This capacity needs a underground space of 200,000㎥, and we can conclude 4 parallel tunnels 550m deep from the surface through the numerical studies, Design parameters were achieved from 300m depth boring job and image processing job.

• 한국통신학회논문지
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• 제40권5호
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• pp.806-808
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• 2015

본 논문은 최근 주목받고 있는 압축 센싱(compressed sensing) 기반으로 직교 주파수 분할 다중화 (OFDM; orthogonal frequency division multiplexing) 신호의 파일럿 톤을 효율적으로 설계하여 최대 전력대 평균 전력 비율 (PAPR; peak to average power ratio)을 감소시키는 방법을 제안한다.

• 한국인쇄학회지
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• 제18권2호
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• pp.55-68
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• 2000

Joint photographic experts group (JPEG) is a standard still-image compression technique, established by the international organization for standardization (ISO) and international telecommunication standardization sector (ITUT). The standard is intended to be utilized in the various kinds of color still imaging systems as a standard color image coding format. Because JPEG is a lossy compression, the decompressed image pixel values are not the same as the value before compression. Various distortions of JPEG compression and JPEG recompression has been reported in various papers. The Image compressed by JPEG is often recompressed by same type compression method in JPEG. In general, JPEG is a lossy compression and the quality of compressed image is predicted that is varied in according to recompression Q-factor. In this paper, four difference color samples(photo image, gradient image, gradient image, vector drawing image, text image) were compressed in according to various Q-factor, and then the compressed images were recompressed according to various Q-factor once again. As the result, this paper evaluate the variation of image quality and file size in JPEG recompression and recommed the optimum recompression factor.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2008년도 정보통신설비 학술대회
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• pp.551-555
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• 2008

In these days, compressed file is useful in internet environment and has many advantages. So a lot of data hiding algorithms works on JPEG compressed file. Of course they know basic rules of transformation and quantization and they utilize those rules to implement their programming. But most of them evaluate the affection of data hiding after data modification. We propose how to predict the affection of data modification in course of data hiding process. Through some kind of experiments, several valuable facts are revealed which used in data hiding in compressed domain such as JPEG. These facts will improve existing data hiding algorithms (F3, F4 and F5 which including Matrix Encoding)[1],[5],[6].

• 전기전자학회논문지
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• 제25권1호
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• pp.76-82
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• 2021

In this paper, the compressed sensing basic pursuit denoise algorithm adopted to synthetic aperture radar imaging is investigated to improve the object recognition. From the incomplete data sets for image processing, the compressed sensing algorithm had been integrated to recover the data before the conventional back- projection algorithm was involved to obtain the synthetic aperture radar images. This method can lead to the reduction of measurement events while scanning the objects. An ultra-wideband radar scheme using a stripmap synthetic aperture radar algorithm was utilized to detect objects hidden behind the box. The Ultra-Wideband radar system with 3.1~4.8 GHz broadband and UWB antenna were implemented to transmit and receive signal data of two conductive cylinders located inside the paper box. The results confirmed that the images can be reconstructed by using a 30% randomly selected dataset without noticeable distortion compared to the images generated by full data using the conventional back-projection algorithm.