DRM 시스템에서 디바이스 식별자를 이용한 효율적인 키 관리 메커니즘

유종화(Zonghua Liu),유광청(Guangqing Liu),이병욱(Byungwook Lee) 한국멀티미디어학회 2008 한국멀티미디어학회 학술발표논문집 Vol.2008 No.2

Security of content encryption key(CEK) is based on asymmetric encryption algorithm in existing DRM systems. Asymmetric algorithm solved the problem with distribution of symmetric key. However, it is slower than symmetric algorithm. In this paper, we propose a key management mechanism which improves efficiency in content consumption while ensuring security. CEK gets protected by symmetric algorithm. User's Device Identifier(DID) is used as symmetric key. When transmitted to license server, DID is encrypted using user's private key to ensure the integrity. DID is unique for each device, and also it is unchangeable. hence, even though it is exposed, it is impossible to decrypt CEK in any other device. In this paper, we examine key's security and efficiency of encrypting and decrypting CEK.

A large-scale test of reinforced soil railway embankment with soilbag facing under dynamic loading

Liu, Huabei,Yang, Guangqing,Wang, He,Xiong, Baolin Techno-Press 2017 Geomechanics & engineering Vol.12 No.4

Geosynthetic reinforced soil retaining walls can be employed as railway embankments to carry large static and dynamic train loads, but very few studies can be found in the literature that investigate their dynamic behavior under simulated wheel loading. A large-scale dynamic test on a reinforced soil railway embankment was therefore carried out. The model embankment was 1.65 meter high and designed to have a soilbag facing. It was reinforced with HDPE geogrid layers at a vertical spacing of 0.3 m and a length of 2 m. The dynamic test consisted of 1.2 million cycles of harmonic dynamic loading with three different load levels and four different exciting frequencies. Before the dynamic loading test, a static test was also carried out to understand the general behavior of the embankment behavior. The study indicated the importance of loading frequency on the dynamic response of reinforced soil railway embankment. It also showed that toe resistance played a significant role in the dynamic behavior of the embankment. Some limitations of the test were also discussed.

Enhanced Visible-Light Photocatalytic Degradation of Antibiotics by MoS2-Modified U-g-C3N4/T-g-C3N4 Isotypic Heterojunction

Hongjin Liu,Yu Wang,Jun Lv,Guangqing Xu,Xinyi Zhang,Yucheng Wu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.9

Based on U-g-C3N4 (U-gCN) and T-g-C3N4 (T-gCN) prepared with urea and thiourea as raw materials, respectively, a visible-light-driven MoS2-modified U-gCN/T-gCN/MoS2 (UTM) ternary heterojunction photocatalyst was successfully prepared using a sonication and bathing method. The photocatalytic activity of as-prepared photocatalyst was evaluated through the degradation of tetracycline hydrochloride (TC) and Rhodamine B (RhB) under the visible light irradiation. The UTM ternary heterojunction showed remarkably enhanced photocatalytic activity. For the degradation of TC and RhB, the degradation rates of 93.9% and 99.9% have been achieved after being irradiated under visible light for 2 h and 1 h, respectively. The enhanced photocatalytic performance can be ascribed to the role of loaded MoS2 cocatalyst and the well-formed interfaces between U-gCN and T-gCN, which not only enhance the light absorption, but also accelerate the separation and transfer of photogenerated electron–hole pairs. Furthermore, UTM ternary heterojunction has excellent recyclability and chemical stability. The photo-degradation rates of 89.9% and 96.78% of TC and RhB have been obtained, respectively, after being reused for five times. Sacrificial agent tests demonstrate that ·O2 - is the major reactive species in the photocatalytic reaction system.

SBA-15 Templated Mesoporous Graphitic C3N4 for Remarkably Enhanced Photocatalytic Degradation of Organic Pollutants under Visible Light

Hongjin Liu,Haining Wu,Jun Lv,Guangqing Xu,Xing Chen,Xinyi Zhang,Yucheng Wu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.11

Organic pollutants in water have been threatening public and environmental health. Developing efficient and sustainable photocatalysts working for degradation of organic pollutants under visible light becomes a big challenge. In this paper, high-efficiency visible light driven catalyst ordered mesoporous graphite nitride carbon (mpg-C3N4) was prepared by using SBA-15 as template and dicyandiamide (C2H4N4) as precursor. The specific surface area of mpg-C3N4 can be increased remarkably as compared to that of the bulk graphite nitrite carbon (g-C3N4) by adjusting the ratio of SBA-15 to dicyandiamide. Photocatalytic performance of mpg-C3N4 were evaluated systematically by degradation of Rhodamine B (RhB), malachite green (MG) and tetracycline hydrochloride (TC) under visible light irradiation. The results showed that the mpg-C3N4 (1 : 0.5) has the highest photocatalytic activity and stability and the degradation rate is for RhB, MG and TC are all more than seven times that of bulk g-C3N4. After five recycling runs, the mpg-C3N4 (1 : 0.5) remains high photocatalytic activities for the degradation of MG (94%) and TC (81%), respectively. Additionally, radical trapping experiments certified that the main active species are ·O2 - and h+, while the role of ·OH is irrelevant in the reaction processes. This work provides a promising pathway to prepare metal-free photocatalyst for degradation of organic pollutants under visible light irradiation.

Enhanced Visible-Light Photocatalytic Remediation of Tetracycline Hydrochloride by Nanostructured BiOI Homojunctions

Mengzhu Qiao,Hongjin Liu,Jun Lv,Guangqing Xu,Xinyi Zhang,Xia Shu,Yucheng Wu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.9

The BiOI homojunctions were constructed between BiOI nanosheets and BiOI nanoflowers, which were prepared with a facile ultrasound-assisted solvothermal method. BiOI nanosheets were uniformly distributed on BiOI nanoflowers surface. The homojunction structure constructed between nanosheets and nanoflowers efficiently speeds up the transfer and separation of photo-induced charge carriers, which is beneficial to promote the photocatalytic activity. Compared with single BiOI, BiOI homojunctions exhibit remarkably improved photocatalytic degradation activity for tetracycline hydrochloride (TC); photodegradation rate of 69.43% for TC has been reached after being irradiated under visible light for 1 h. Deeper analyses of photocatalytic degradation mechanism of TC have been conducted; the results identify that ·O2 - and h+ play important roles during the TC degradation reaction.

Selective deposition of Au-Pt alloy nanoparticles on ellipsoidal zirconium titanium oxides for reduction of 4-nitrophenol

Zewu Zhang,Jinghui Zhang,Guangqing Liu,Mengwei Xue,Zhangzhong Wang,Xiaohai Bu,Qiong Wu,Xuejuan Zhao 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.9

Au-Pt alloy nanoparticles that are selectively anchored on TiO2 surface of the ellipsoidal zirconium titanium composite oxides were successfully prepared by a facile two-step method: prefabricated binary composite oxides on the ellipsoidal Fe2O3@SiO2 by a versatile cooperative template-directed coating method, and then in situ formation of Au-Pt alloy NPs with Sn2+ as the reduction agent. The alloy catalysts were characterized by X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The result suggested that highly dispersive and ultrafine Au-Pt alloy nanoparticles were deposited onto TiO2 surface of the binary oxides solely. The particle size of nanoalloys was closely related to the ratio of Zr : Ti in the composite oxides shell. Increasing the content of Zr element led to a growth in the size of alloy nanoparticles. When used as catalysts for the reduction of 4-nitrophenol, the prepared supported alloyed catalysts exhibited high catalytic activity, and the sample could be easily recycled without a significant decrease of the catalytic activity.

Impact of variations in fatty liver on sonographic detection of focal hepatic lesions originally identified by CT

Size Wu,Rong Tu,Ruixia Nan,Guangqing Liu,Xiaojing Cui,Xian Liang 대한초음파의학회 2016 ULTRASONOGRAPHY Vol.35 No.1

Purpose: The aim of this study was to investigate the influence of variations in fatty liver on the ultrasonographic detection of focal liver lesions. Methods: A total of 229 patients with varying degrees of fatty liver and focal liver lesions and 200 patients with focal liver lesions but no fatty liver were randomly selected for inclusion in groups I and II, respectively. Findings of focal liver lesions identified on computed tomography were taken as the reference, and findings on ultrasonography were compared with them. Results: The number of focal liver lesions in groups I and II were 501 and 413, respectively. The ultrasonographic detection rates of focal liver lesions in groups I and II were 86.8% (435/501) and 94.2% (389/413), respectively. Comparison of the detection of the focal lesions between patients with and without fatty liver or different grades of fatty liver were as follows: mild fatty liver (162/177) vs. liver without fat infiltration (389/413) (P=0.277); mild fatty liver (162/177) vs. moderate fatty liver (190/212) (P=0.604); mild fatty liver (162/177) vs. severe fatty liver (83/112) (P<0.001); moderate fatty liver (190/212) vs. liver without fat infiltration (389/413) (P=0.051); moderate fatty liver (190/212) vs. severe fatty liver (83/112) (P<0.001); severe fatty liver (83/112) vs. liver without fat infiltration (389/413) (P<0.001); and fatty liver (435/501) vs. liver without fat infiltration (389/413) (P<0.001). Conclusion: Mild and moderate fatty liver are not significantly associated with the visualization of the lesion, while severe fatty liver usually impairs the detection of focal lesions in the liver. If a patient with severe fatty liver is suspected to have a liver tumor, ultrasonography should only be chosen cautiously in case of a missed diagnosis.

Codon optimization of the rabbit hemorrhagic disease virus (RHDV)capsid gene leads to increased gene expression in Spodoptera frugiperda 9 (Sf9) cells

Jingpeng Gao,Chunchun Meng,Zongyan Chen,Chuanfeng Li,Guangqing Liu 대한수의학회 2013 Journal of Veterinary Science Vol.14 No.4

Rabbit hemorrhagic disease (RHD) is contagious and highly lethal. Commercial vaccines against RHD are produced from the livers of experimentally infected rabbits. Although several groups have reported that recombinant subunit vaccines against rabbit hemorrhagic disease virus (RHDV) are promising, application of the vaccines has been restricted due to high production costs or low yield. In the present study, we performed codon optimization of the capsid gene to increase the number of preference codons and eliminate rare codons in Spodoptera frugiperda 9 (Sf9) cells. The capsid gene was then subcloned into the pFastBac plasmid, and the recombinant baculoviruses were identified with a plaque assay. As expected,expression of the optimized capsid protein was markedly increased in the Sf9 cells, and the recombinant capsid proteins self-assembled into virus-like particles (VLPs) that were released into the cell supernatant. Rabbits inoculated with the supernatant and the purified VLPs were protected against RHDV challenge. A rapid, specific antibody response against RHDV was detected by an ELISA in all of the experimental groups. In conclusion, this strategy of producing a recombinant subunit vaccine antigen can be used to develop a low-cost, insect cell-derived recombinant subunit vaccine against RHDV.