http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Sharing and Privacy in PHRs: Efficient Policy Hiding and Update Attribute-based Encryption
( Zhenhua Liu ),( Jiaqi Ji ),( Fangfang Yin ),( Baocang Wang ) 한국인터넷정보학회 2021 KSII Transactions on Internet and Information Syst Vol.15 No.1
Personal health records (PHRs) is an electronic medical system that enables patients to acquire, manage and share their health data. Nevertheless, data confidentiality and user privacy in PHRs have not been handled completely. As a fine-grained access control over health data, ciphertext-policy attribute-based encryption (CP-ABE) has an ability to guarantee data confidentiality. However, existing CP-ABE solutions for PHRs are facing some new challenges in access control, such as policy privacy disclosure and dynamic policy update. In terms of addressing these problems, we propose a privacy protection and dynamic share system (PPADS) based on CP-ABE for PHRs, which supports full policy hiding and flexible access control. In the system, attribute information of access policy is fully hidden by attribute bloom filter. Moreover, data user produces a transforming key for the PHRs Cloud to change access policy dynamically. Furthermore, relied on security analysis, PPADS is selectively secure under standard model. Finally, the performance comparisons and simulation results demonstrate that PPADS is suitable for PHRs.
Dirac semimetal-enabled multi-bit coding metasurface for dynamic manipulation of terahertz beams
Zhang Yonggang,Yin Kehao,Liang Lanju,Yao Haiyun,Yan Xin,Hu Xiaofei,Huang Chengcheng,Qiu Fu,Zhang Rui,Li Yuanping,Wang Yaru,Li Zhenhua,Wang Ziqun 한국물리학회 2024 Current Applied Physics Vol.58 No.-
In this study, a switchable multi-bit coding metasurface that is applied under a terahertz (THz) frequency by adjusting the Fermi level (EF) of Dirac semimetals (DSMs) is proposed. At a EF of 0.2 eV, a 1-bit coding metasurface can be applied in the 2.58–2.62 THz. At 0.3 eV, a 3-bit coding metasurface is realized at 1.88 THz, and at 0.05 eV, the phase of the coding units coincides in the 1.5–3 THz. So, different functions of the metasurface can be realized. The proposed coding metasurfaces has promising applications in terahertz communication.
Characteristics of Micro-structure of Warm and Ice-Rich Frozen Soil Improved by Cement and Additives
Mingtang Chai,Jianming Zhang,Hu Zhang,Zhenhua Yin 대한토목학회 2021 KSCE JOURNAL OF CIVIL ENGINEERING Vol.25 No.10
In permafrost regions, the warm and ice-rich frozen soil (WIRFS) underlying the embankment has a low strength and large compressibility, which threatens the engineering stability. The addition of cement and its additives can improve the mechanical properties of the WIRFS. During the curing and the thawing compression, the micro-structure of the improved WIRFS was changed by hydration reaction and deformation. In this paper, the porosity and directionality of soil were selected as indicators to reflect the variation of micro-structure in the improved WIRFS. Two image processing methods, fuzzy C-means clustering and image segmentation, were introduced to quantitatively calculate the porosity and the directionality of soil particles. The arrangement variation of soil aggregates can reflect the characteristics of micro-structure during the soil improvement. The results indicate that, the addition of cement and additives reduced the directionality of sample before the thawing compression. After the compression, except for the super absorbent polymer, ironic agent, EN-1, Toogood and geopolymer, the addition of antifreeze agent, early strength agent and metakaolin increased the directionality. The average porosity is negatively relevant to the compressibility coefficient. This paper has connected the micro-structure with deformation parameter of the improved frozen soil, which can reflect the improvement mechanism with cement and additives.