• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.200-203
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• 2013

본 논문에서는 시장 점유율 상위를 차지하는 3 종의 해외 유명 제조사의 상용 HD 급 실시간 방송용 H.264 인코더의 화질 성능에 대해 전 기준 화질 평가를 통해 비교한다. 이를 위해 VQEG(Video Quality Experts Group)등에서 배포하는 9 종의 기준영상을 이용하여 PSNR(Peak Signal to Noise Ratio)을 측정하였으며 인코더 별 성능 비교를 위해 9 종의 기준영상에 대한 평균 PSNR 과 인코더/디코더의 전체 지연시간을 측정하였다. 그 결과 장비 별로 조금씩 다른 특성 결과와 현재 H.264 인코더 시험 시 성능 평가의 애매한 부분이었던 화질에 대한 벤치마크 결과를 얻을 수 있었다. 본 논문의 실험 결과는 국산 방송용 인코더의 객관적인 성능 평가를 위한 지표로 사용될 수 있을 것으로 예측된다.

• Journal of the Korean Society of Radiology
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• v.8 no.2
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• pp.65-74
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• 2014

This study extracts characteristics of signal by wavelet transform to prove that the Compton scattering, occurred by changed the energy, influenced a picture. We also analyzed the extracted data and evaluated how much the picture of scatter-rays was affected by a change of tube voltage. For this study, we wrote a program with MatLap which is engineering tool and evaluated with the program on variation of scattered-rays due to increased tube voltage. The evaluation result shows both CR and DR have frequency changes of high frequency area by tube voltage variations and it proved that Compton scattering influences the picture. In conclusion, according to this study indicates that DR is more sensitive to radiation with high energy than CR. Therefore, the research on DR detector needs to be advanced as actual condition of clinical setting is being changed to DR circumstance gradually. From the result of this study, we expect that assessment method of the image quality using MatLab Tool becomes the official assessment method and very useful method.

• Journal of Broadcast Engineering
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• v.14 no.2
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• pp.127-133
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• 2009

With advances in video technology, many researchers are interested in video quality assessment to prove better performance of proposed algorithms. Since human visual system is too complex to be formulated exactly, many researches about video quality assessment are in progressing. No-reference video-quality assessment is suitable for various video streaming services, because of no requested additional data and network capacity to perform quality assessment. In this paper, we propose a novel no-reference video-quality assessment method with the estimation of dynamic range distortion. To measure the performance, we obtain mean opinion score (MOS) data by subject video quality test with the ITU-T P.910 Absolute Category Rating (ACR) method. And, we compare it with proposed algorithm using 363 video sequences. Experimental results show that the proposed algorithm has a higher correlation with obtained MOS.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.3
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• pp.37-45
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• 2008

Quality assessment ai s to evaluate if a distorted image or video has a good quality by measuring the difference between the original and distorted images or videos. In this paper, to assess the visual qualify of a distorted image or video, visual features of the distorted image are compared with those of the original image instead of the direct comparison of the distorted image with the original image. We use edge projections from two images as features, where the edge projection can be easily obtained by projecting edge pixels in an edge map along vertical/horizontal direction. In this paper, edge projections are obtained by using vertical/horizontal directions of gradients as well as the magnitude of each gradient. Experimental results show the effectiveness of the proposed quality assessment through the comparison with conventional quality assessment algorithms such as structural similarity(SSIM), edge peak signal-to-noise ratio(EPSNR), and edge histogram descriptor(EHD) methods.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2000.11a
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• pp.131-135
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• 2000

본 연구에서는 연령·조명·프로그램 종류에 따른 TV 최적 화질의 설정치를 규명하고, 최적 화질에 대한 감성구조를 규명하는 것이 목적이다. 아동, 성인 그리고 노인이 실험에 참여하였고, 세 가지 조명 조건에 따라 영화, 만화영화 (애니메이션), 드라마, 다큐멘터리의 화면이 제시되었다. 실험 참여자들은 화면을 보는 동안, 리모콘을 사용하여 가장 만족스러운 화면을 설정하였다. 또한 설정한 최적화질에 대해 감성을 평가하였다. 그 결과, 연령·조명·프로그램 종류에 따라 최적 화질에 대한 설정치가 다르게 나타났다. 화질에 대한 감성구조는 두 차원 (쾌-불쾌 및 감각특성, 미적특성)으로 나타났으며, 연령에 따라 감성구조가 다르게 나타났다.

• Journal of The Korean Radiological Technologist Association
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• v.28 no.1
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• pp.359-360
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• 2002

• Journal of the Korea Society of Computer and Information
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• v.18 no.8
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• pp.53-64
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• 2013

The existing research on the QoS of the Streaming video system(SVS) adjust the video stream being sent from the network perspective, the focus is to prevent data loss and delay. The other hand, changing the quality of the video stream will not receive the guaranteed QoS from the perspective of the users who want uniform quality. In order to solve these problems, this paper applied to ensure that the benefits in the amount of bits per frame occurs Encoder CBR streaming video is kept constant and uniform picture quality advantages of VBR streaming video VBR to CBR Encoder and CBR to VBR Decoder, Video was designed to control the playback stream for And to ensure a uniform quality of the user based on the design and implementation of uniform quality guaranteed SVS. PSNR evaluated for several characteristics of the sample video to demonstrate the superiority of the SVS ensure uniform quality, the proposed Performance evaluation of the SVS ensure uniform quality CBW the ABR from 100% to ensure uniform image quality from 85% to environmental excellence is proved.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.133-136
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• 2006

한정된 네트워크 대역폭을 가진 현재의 인터넷에서 영상의 품질을 향상시키기 위해 영상의 비트율을 높이는 것은 비용 등 여러 가지 문제로 인해 현실적으로 많은 어려움이 있다. 따라서 비록 충분하지 못한 비트율의 영상을 전송받더라도 전송받은 영상의 화질을 높이는 연구가 다양한 방법으로 진행되고 있다. 영상의 화질을 향상시키는 많은 방법 중 후처리 기법은 이러한 잡음을 효과적으로 제거 할 수 있으면서 동영상 압축 표준 복호기를 수정할 필요가 없기 때문에 좋은 해결책이 된다. 동영상의 압축 과정에서 낮은 비트율로 인해 발생하는 화질 열화 현상 중에 쉽게 완화 할 수 있고, 영상의 질이 비용 대비 높은 효율로 좋아지는 대표적인 현상이 블록화 현상이다. 일반적으로 블록화 현상은 영상의 고주파대역에서 나타나므로 본 논문에서 영상의 고주파 성분과 블록화 현상을 구분하기 위해 Sobel 마스크를 사용한다. 구분된 블록화 현상이 발생한 매크로블록의 양쪽 경계면에 4-tap 저주파 통과 필터를 사용하여 블록화 현상을 효과적으로 완화할 수 있다. 개선된 영상의 화질 평가 기법으로 신호처리 분야에서 많이 사용되는 객관적인 지표인 PSNR에 의한 평가와 함께 실제 인간의 시각을 기준으로 주관적이고 감성적인 관찰에 의한 평가를 함께 수행한다.

• Journal of radiological science and technology
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• v.33 no.4
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• pp.341-348
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• 2010

By accessing the current status of FPD system use in the hospitals located in Seoul and Gyeonggi Province as well as the entrance skin dose and the image quality evaluation realized by C-D Phantom, and the image assessment by the medical professionals regarding the radiography for the extremity, the following results were derived. 1. According to the evaluation made in the actual use of FPD system (12 machines), the grid ratio varied from 8:1 to 13:1, and 6 machines used the grid ratio with 12:1, realizing the largest number. Among the machines, there were 8 machines that allowed a removable grid while 3 machines did use a removable grid (25.0%). 2. When it came to the equipments used for the experiment, it showed that the amount of the entrance skin dose increased from 4.13 times up to 4.79 times with the grid use. 3. The difference in the entrance skin dose depending on the changes in the exposure condition(0.5times or 2.0times) was not significantly different regardless of the patients' thickness. 4. In terms of the image quality depending on C-D Phantom, the grid use was distinguished well. However, the images were well distinguishable as the exposure condition got increased. 5. In the clinical assessment, the grid use was less effective for the Hand PA, which was considered to shoot a thin body part. It was evaluated that the grid use was preferred for the Knee AP, which was shooting for a relatively thick body part. Nonetheless, 3 out of 5 people said that they would not use the grid if the entrance skin dose to reduced.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.283-296
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• 2013

Various video services with networks are increasingly available as smart phones, computers and IPTV are widely used. However, transmission over networks may experience transmission errors due to traffic increases and noise. As a result, video quality may suffer. Therefore, quality monitoring emerges as an important issue. In this paper, we propose a video quality assessment method using bit stream information. The video quality metric is calculated using header information and ES (elementary stream) information. To assess performance of the proposed algorithm, subjective quality assessment tests are conducted (VGA resolution). It is shown high correlation between subjective result and the proposed method.