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RISS 인기검색어
- 검색키워드
- 저자 : Vo Nam Son (검색결과 2 건)
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Reversible Data Hiding Algorithm Based on Pixel Value Ordering and Edge Detection Mechanism
Thai-Son Nguyen,Hoang-Nam Tram,Phuoc-Hung Vo 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.10
Reversible data hiding is an algorithm that has ability to extract the secret data and to restore the marked image to its original version after data extracting. However, some previous schemes offered the low image quality of marked images. To solve this shortcoming, a new reversible data hiding scheme based on pixel value ordering and edge detection mechanism is proposed. In our proposed scheme, the edge image is constructed to divide all pixels into the smooth regions and rough regions. Then, the pixels in the smooth regions are separated into non overlapping blocks. Then, by taking advantages of the high correlation of current pixels and their adjacent pixels in the smooth regions, PVO algorithm is applied for embedding secret data to maintain the minimum distortion. The experimental results showed that our proposed scheme obtained the larger embedding capacity. Moreover, the greater image quality of marked images are achieved by the proposed scheme than that other previous schemes while the high EC is embedded.
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Phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam
Nguyen Thi Kim Lien,Phan Thi Cam Tu,Vo Nam Son,Huynh Truong Giang 한국수산과학회 2023 Fisheries and Aquatic Sciences Vol.26 No.8
Algal overgrowth in shrimp culture ponds can affect the quality of the aquatic environment, thereby adversely affecting the shrimp and causing economic losses. The objective of this study was to evaluate the variation in phytoplankton composition in intensive shrimp ponds in Bac Lieu province, Vietnam. Phytoplankton samples were collected in three black tiger shrimp (Penaeus monodon) ponds and three whiteleg shrimp (Litopenaeus vannamei) ponds. The collected data were analyzed using SPSS and canonical correlation analysis softwares. In total, 75 species of phytoplankton were recorded in black tiger shrimp ponds and 64 species in whiteleg shrimp ponds. Diatoms had the highest species diversity with 29–30 species (39%–47%), followed by green algae with 9–19 species (14%–25%); species numbers of other phyla varied from 5–12 (8%–16%). The total number of phytoplankton species throughout the study varied from 34–50 species. Algal density was relatively high and ranged from 497,091–2,229,500 ind./L and 1,301,134–2,237,758 ind./L in black tiger shrimp and whiteleg shrimp ponds, respectively. The diatom density tended to increase during the final stage of the production cycle in black tiger shrimp ponds. Blue-green algae and dinoflagellates also increased in abundance at the end of the cycle, which can affect shrimp growth. Diatoms were significantly positively correlated with pH, salinity, total ammonia nitrogen, and nitrate (NO3 –) concentrations (p < 0.05). Blue-green algae and dinoflagellates were positively correlated with salinity, phosphate (PO4 3–), and NO3 –. Algal species diversity was lower in the whiteleg shrimp ponds than in the black tiger shrimp ponds. Several dominant algal genera were recorded in the shrimp ponds, including Nannochloropsis, Gyrosigma, Chaetoceros, Alexandrium, and Microcystis. The results of this study provide basic data for further investigations, and they contribute to the management of algae in brackish-water shrimp ponds.
ScienceON
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