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잡음 모델 선택을 이용한 Wyner-Ziv 비디오 압축
박천호(Chunho Park),심혁재(Hiuk Jae Shim),전병우(Byeungwoo Jeon) 대한전자공학회 2009 電子工學會論文誌-SP (Signal processing) Vol.46 No.4
최근 경량화 비디오 부호화를 위함 분산 비디오 부호화 기술 (DVC: Distributed Video Coding)에 대한 연구가 활발히 이루어지고 있으며, Wyner-Ziv 부호화 기술은 이의 대표적인 기술로써 각광받고 있다. Wyner-Ziv (WZ) 부호화기는, 영상을, 기존의 인트라 부호화기를 이용하는 키 (Key) 프레임과 WZ 부호화를 하는 WZ 프레임으로 나누어 독립적으로 부호화 한다. WZ 복호화기로 전송된 키 프레임은 복원된 뒤 키 프레임 사이의 WZ 프레임을 추정하는데 사용되며 추정된 WZ 프레임을 보조정보 (Side Information)라고 한다. 보조정보는 WZ 프레임에 대한 정보가 없는 상태에서 추정되므로 필연적으로 WZ 프레임과 다르며 WZ 복호화기에서는 보조정보와 WZ 프레임과의 차이를 가상의 채널 잡음으로 간주한다. WZ 복호화 과정은 가상의 채널잡음을 WZ 복호화기 내에 존재하는 채널코드를 이용하여 제거함으로써 이루어지므로 채널 정보를 정확히 아는 것은 채널코드의 에러정정능력에 큰 영향을 미친다. WZ 복호화기에서는 추정된 WZ 영상만이 존재하므로 정확한 잡음의 양을 알 수 없으며, 일반적으로 선형 움직임에 근거한 키 프레임 간의 차를 하나의 예측 수단으로 사용한다. 또한 이와 같이 예측이 갖는 불확실성으로 채널코드의 효율이 저하되는 것을 막기 위하여 주변의 잡음과 비교를 통한 잘못된 잡음을 정정하는 방법도 제안되었다. 하지만 이런 방법들이 모든 프레임이나 비트 플레인에 존재하는 잡음을 제대로 측정한다고 할 수는 없다. 따라서 본 논문에서는 여러 개의 후보 잡음 모델을 생성한 후, 복호화 과정에서 가장 효율적인 모델을 선택하는 방법을 제안한다. 제안 방법에 대한 실험결과는 최대 0.8 dB의 PSNR이득을 보여준다. Recently the emerging demands of the light-video encoder promotes lots of research efforts on DVC (Distributed Video Coding). As an appropriate video compression method, DVC has been studied, and Wyner-Ziv (WZ) video compression is its one representative structure. The WZ encoder splits the image into two kinds of frames, one is key frame which is compressed by conventional intra coding, and the other is WZ frame which is encoded by WZ coding. The WZ decoder decodes the key frame first, and estimates the WZ frame using temporal correlation between key frames. Estimated WZ frame (Side Information) cannot be the same as the original WZ frame due to the absence of the WZ frame information at decoder. As a result, the difference between the estimated and original WZ frames are regarded as virtual channel noise. The WZ frame is reconstructed by removing noise in side information. Therefore precise noise estimation produces good performance gain in WZ video compression by improving error correcting capability by channel code. But noise cannot be estimated precisely at WZ decoder unless there is good WZ frame information, and generally it is estimated from the difference of corresponding key frames. Also the estimated noise is limited by comparing with frame level noise to reduce the uncertainty of the estimation method. However these methods cannot provide good noise estimation for every frame or each bit plane. In this paper, we propose a noise nodel selection method which chooses a better noise model for each bit plane after generating candidate noise models. Experimental result shows PSNR gain up to 0.8 ㏈.
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박주경(Jukyung Park),장유진(Eujean Jang),박천호(Chunho Pak) 인간식물환경학회 2015 인간식물환경학회지 Vol.18 No.6
This study examined the current status of the types of edible flowers used domestically and overseas and the discovery and utilization methods of edible flowers naturally growing in Korea, analyzed the types of edible flowers that have been reported until present in order to seek a development method to strengthen competitiveness in the edible flower industry. Domestic and overseas records contain records of 406 species in 80 families of edible flowers. There were 38 species in 18 families of edible flowers appearing in at least 50% of the records, and per family, the Asteraceae, and per type, the Viola spp. type appeared most frequently. A total of 127 species in 36 families appeared in overseas records. There were 27 species in 15 families of edible flowers appearing in at least 60% of the records, and per family, the Asteraceae, and per type, Borago officinalis, Dianthus spp., Lavandula spp., Tropaeolum majus sp. and Viola spp. appeared most frequently. A total of 381 species in 78 families appeared in domestic records. There were 62 species in 26 families of edible flowers appearing in at least 60% of the records, and per family, the Asteraceae and Lamiaceae appeared most frequently, while per type, Dendranthema spp., Hemerocallis fulva, Rosa spp., Taraxacum platycarpum Dahlst., and Viola spp. appeared most frequently. Thus, in order for the edible flower industry to achieve development in the future, there would be a need to make efforts to expand consumption of edible flowers, such as through discovery of naturally growing flowers, research on production and storage technology, promotional activities and research on its functionality, and development of various processed goods through mass industrialization.
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Monitoring of Butyltin Compounds Between 1992 and 2009 in Korean Bays
이성언(Seongeon Lee),박천호(Chunho Park),성락규(Rockkyu Sung),이동섭(Dongsup Lee) 한국해양환경·에너지학회 2009 한국해양환경공학회 학술대회논문집 Vol.2009 No.11월
As of 2003, the use of tributyltin (TBT) has been prohibited in Korea. The results of the tests for concentrations of butyltin compounds from this lab in 1992 were compared with those from the same sites in 2006 and 2009. The annual average of each year was used to demonstrate the declining amount of TBT, which dropped from 12.76 ng/L in 1992 to 6.21 ng/L in 2006 and 1.61 ng/L in 2009. The TBT frequency detection was 70% in 1992, 61% in 2006, and 11% in 2009. Therefore, it is the conclusion of the authors that overall TBT use in Korea is declining. Nevertheless, butyltin compounds were still detected at several sites in Koreaat high concentrations. Accordingly, the concentration of butyltin compounds along specific Korean coastal sites needs to be constantly monitored.
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