• Journal of Microbiology and Biotechnology
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• v.22 no.8
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• pp.1170-1176
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• 2012

In this study, we aimed to evaluate the effect of ${\alpha}$-cyperone on S. aureus. We used a hemolysin test to examine the hemolytic activity in supernatants of S. aureus cultured with increasing concentrations of ${\alpha}$-cyperone. In addition, we evaluated the production of ${\alpha}$-hemolysin (Hla) by Western blotting. Real-time RT-PCR was performed to test the expression of hla (the gene encoding Hla) and agr (accessory gene regulator). Furthermore, we investigated the protective effect of ${\alpha}$-cyperone on Hla-induced injury of A549 lung cells by live/dead and cytotoxicity assays. We showed that in the presence of subinhibitory concentrations of ${\alpha}$-cyperone, Hla production was markedly inhibited. Moreover, ${\alpha}$-cyperone protected lung cells from Hla-induced injury. These findings indicate that ${\alpha}$-cyperone is a promising inhibitor of Hla production by S. aureus and protects lung cells from this bacterium. Thus, ${\alpha}$-cyperone may provide the basis for a new strategy to combat S. aureus pneumonia.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1027-1036
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• 2020

Stipa purpurea is a unique and dominant herbaceous plant species in the alpine steppe and meadows on the Qinghai-Tibet Plateau (QTP). In this work, we analyzed the composition and diversity of the culturable endophytic fungi in S. purpurea according to morphological and molecular identification. Then, we investigated the bioactivities of these fungi against plant pathogenic fungi and 1-aminocyclopropane-1-carboxylate deaminase (ACCD) deaminase activities. A total of 323 fungal isolates were first isolated from S. purpurea, and 33 fungal taxa were identified by internal transcribed spacer primers and grouped into Ascomycota. The diversity of endophytic fungi in S. purpurea was significantly higher in roots as compared to leaves. In addition, more than 40% of the endophytic fungi carried the gene encoding for the ACCD gene. The antibiosis assay demonstrated that 29, 35, 28, 37 and 34 isolates (43.9, 53.1, 42.4, 56.1, and 51.5%) were antagonistic to five plant pathogenic fungi, respectively. Our study provided the first assessment of the diversity of culture-depending endophytic fungi of S. purpurea, demonstrated the potential application of ACCD activity and antifungal activities with potential benefits to the host plant, and contributed to high biomass production and adaptation of S. purpurea to an adverse environment.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.5
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• pp.512-516
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• 2008

A conference-key agreement protocol is essential for computer network conferences that need secure communications. Especially, the fault-tolerant conference-key agreement can make a shared conference-key even if some make conferees disturb the key agreement processes. However, the performance of the previous fault-tolerant conference-key agreement protocols is decreasing significantly when the number of fake conferees is increasing. In this paper, we propose an efficient fault-tolerant conference key agreement protocol. Our scheme is based on the ID-based one round tripartite conference key agreement protocol. Simulation results show our scheme's efficiency against Yi's method especially when the number of fake conferees is large.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.1
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• pp.3-10
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• 2013

Several identity-based and authenticated key agreement protocols have been proposed. It remains at issue to design secure identity based and authenticated key agreement protocols. In this paper, we propose a one round authenticated group key agreement protocol which uses one more key pair as well as the public key and private key of typical IBE(Identity-Based Encryption) system. The proposed protocol modified Shi et al.'s protocol and He et al.'s protocol. The public and private keys and the signature process of our protocol are simpler than them of their protocols. Our protocol is secure and more efficient than their protocols in communication and computation costs.

• Journal of Microbiology
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• v.41 no.2
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• pp.152-156
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• 2003

Through enrichment on two nutrient agars, 57 Thermus isolates were recovered from 15 hot spring samples taken from the Rehai geothermal area, Tengchong, China. Unique growth characteristics were observed when the strains were transferred from YIM14 medium to Thermus medium. Phylogenetic analysis showed that the 16S rDNA sequences of the isolates and clones from the Rehai geothermal area farmed a monophyletic group on the phylogenetic tree. A secondary structure comparison showed that their 16S rRNAs have unique secondary structure characteristics.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.2
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• pp.546-555
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• 2015

The aims of this study were to analyze the coastal Fisherman's awareness for the Fisheries and Maritime Job Skills. Fisheries & Maritime key competencies were defined as the abilities that include the essential knowledge, skills, attitude, and experiences required for the workforce on the fisheries and maritime job condition. This research collected preliminary data from 65 coastal fishermen. Data were analyzed to obtain content validity analysis. The results of the study were as follows; First, Fisheries & Maritime key competencies were divided into 6 elements in coastal fisheries. Second, Fisheries & Maritime key competencies were consisted of basic skills, marine vocational ethics, marine information capacity, marine elementary knowledge, marine safety management skill and marine consciousness. Third, CVR proves that the value analyzed in the study was validation. In consequence, the study suggested that Fisheries & Maritime key competencies were different in accordance with work environment.

• International Journal of Quality Innovation
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• v.6 no.3
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• pp.19-37
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• 2005

It is generally accepted that leadership is the foundation for creation of a company's business results. However, empirical evidence is lacking. This paper examines the relationship between leadership and key performance results based on a Return on Leadership Model. The model links Denison's four leadership traits to people results, customer results, and ultimately key performance results. Further specified, the model is a structural equation model with nine latent variables, each measured by a set of indicators, observed by survey questions. To validate the model, an empirical study was conducted, and 379 managers from medium-sized and large companies in Denmark participated. The estimation of the model shows that the model structure explains return on leadership very well, and the findings support the developed model. We are able to quantify the relationships from leadership to people results, customer results and key performance results and, in this way, the data presented here provide evidence that leadership is linked to key performance results. Several results and applications of the model are shown. The findings provide new knowledge about how leadership can be linked to performance, and how excellent leadership creates key performance results.

• The Journal of Information Technology
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• v.5 no.2
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• pp.35-45
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• 2002

This paper discusses a distributed implementation of the Biba security policy model. Implementation of an service in the OSI-RM is not sufficient for enforcing the Biba model. Also confidentiality services are necessary. Public Key Systems(PKSs) are considered for the realization of these security services. In this paper symmetric & asymmetric cryptographic systems are considered for the realization of these security service. It is investigated how key-distributions can be found resulting in a minimum number of key.

• ETRI Journal
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• v.37 no.3
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• pp.573-583
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• 2015

We introduce the idea of a forward-secure undetachable digital signature (FS-UDS) in this paper, which enables mobile agents to generate undetachable digital signatures with forward security of the original signer's signing key. The definition and security notion of an FS-UDS scheme are given. Then, the construction of a concrete FS-UDS scheme is proposed; and the proof of security for the proposed scheme is also provided. In the proposed scheme, mobile agents need not carry the signing key when they generate digital signatures on behalf of the original signer, so the signing key will not be compromised. At the same time, the encrypted function is combined with the original signer's requirement; therefore, misuse of the signing algorithm can be prevented. Furthermore, in the case where a hacker has accessed the signing key of the original signer, he/she is not able to forge a signature for any time period prior to when the key was obtained.

• Journal of Broadcast Engineering
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• v.13 no.1
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• pp.79-85
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• 2008

An authenticated group key agreement protocol allows a group of parties communicating over an insecure network to share a common secret key. In this paper, we show that Zhou et al.'s ID-based authenticated group key agreement schemes do not provide forward secrecy.