• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.34.2-34.2
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• 2010

Cosmic rays registered by Neutron Monitors on the surface of the Earth are believed to be coming from outer space, and sometimes also from the exotic objects of the Sun. Ground level enhancement (GLE) is the sudden, sharp and short-lived increase in cosmic rays originated from the Sun. Since GLE is the signature in solar cosmic ray intensity, different solar factors erupted from the Sun can be responsible for causing it. In this context, an attempt has been made to determine quantitative relationships of GLEs > 5% with simultaneous solar, interplanetary and geophysical factors from 1997 through 2006 thereby searching the perpetrators which seem to be causing them. The study has revealed that solar flares are stronger ($0.71{\times}10-4$ w/m2) during GLE peaks than the solar flares ($1.10{\times}10-5$ w/m2) during GLE non-peaks and backgrounds. On the average, the solar wind plasma velocity and interplanetary magnetic field are found stronger during the GLE peaks than the GLE non-peaks and backgrounds indicating that the solar flares, in conjunction with interplanetary shocks, sometimes may cause GLE peaks. Direct proportionality of GLE peaks to simultaneous solar energetic particle (SEP) fluxes imply that the GLE peaks may often be caused by SEP fluxes. Although the high intensity of SEP fluxes are also seen extended few minutes even after GLE peaks, the mean (373.62 MeV) of the GLE associated SEP fluxes is much stronger than the mean (10.35 MeV) of the non-GLE associated SEP fluxes. Evidences are also supported by corresponding SEP fluences that the the mean fluence (${\sim}5.32{\times}107/cm2$) across GLE event was more intense than the mean fluence (${\sim}2.53{\times}106/cm2$) of SEP fluxes across non-GLE event.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.89-103
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• 2001

Through the increment of requirement for group oriented communication services, the multicast infrastructure based on a wire and wireless network has become a widely discussed researching topic. However the research of the security properties safety, efficiency and scaleability in a multicast structure, has not been enough. In this study, we propose a scalable secure multicast key management structure based on PKI(Public Key Infrastructure), IPSec, domain subgroup and structural two mode scheme to provide a integrated multicast service. Also we discuss and propose the digital nominative group signature a refreshing method for satisfying the security and trusty on the network. At the base of this work we certify to the usability of new proposed scheme from comparing it with conventional schemes in the part of safety, efficiency and scaleability.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.5
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• pp.181-195
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• 2011

There's a controversy about an invasion of privacy which includes a leakage of private information and linking of user's behavior on internet. Although many solutions for this problem are proposed, we think anonymous authentication, authorization, and payment mechanism is the best solution for this problem. In this paper, we propose an effective anonymity-based method that achieves not only authentication but also authorization. Our proposed method uses anonymous qualification certificate and group signature method as an underlying primitive, and combines anonymous authentication and qualification information. An eligible user is legitimately issued a group member key pair through key issuing process and issued some qualification certificates anonymously, and then, he can take the safe and convenience web service which supplies anonymous authentication and authorization. The qualification certificate can be expanded according to application environment and it can be used as payment token.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.34 no.2
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• pp.167-177
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• 2024

This paper proposes optimization techniques for SeaSign, an isogeny-based digital signature algorithm. SeaSign combines class group actions of CSIDH with the Fiat-Shamir with abort. While CSIDH-based algorithms have regained attention due to polynomial time attacks for SIDH-based algorithms, SeaSiogn has not undergone significat optimization because of its inefficiency. In this paper, an efficient signing method for SeaSign is proposed. The proposed signing method is simple yet powerful, achived by repositioning the rejection sampling within the algorithm. Additionally, this paper presnts parameters that can provide optimal performance for the proposed algorithm. As a result, by using the original parameters of SeaSign, the proposed method is three times faster than the original SeaSign. Additonally, combining the newly suggested parameters with the signing method proposed in this paper yields a performance that is 290 times faster than the original SeaSign and 7.47 times faster than the method proposed by Decru et al.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.9
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• pp.4214-4223
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• 2012

The argument related to the use of real and anonymous names on the Internet bulletin board has recently become a main issue. When using real names, it is possible to violate free discussion and privacy. Also, when using anonymous names, it is possible to have the reverse function of the Internet in regard to the use of malicious replies or the distribution of false ideas. Therefore, this paper has made it possible to prevent the spread of the user's personal information and execute the single log-in process by using the XML-token method which is one of the SSO technologies. Also, by issuing virtual IDs and forming the path when establishing tokens, the anonymous bulletin board which provides anonymity with a conditional tracing process has been suggested. After analyzing the performance of visitor numbers at authentication time, the anonymous bulletin board based on the group signature method showed the average response rate of 0.72 seconds, 0.18 seconds, which was suggested scheme. In the authentication time 4-5 times faster response speed, respectively. Also, since the suggested system does not have to provide a single authentication process or make the user provide his or her signature, the level of user's convenience seems to be much higher. Such a result shows that the system suggested on the anonymous bulletin board has a more appropriate level of user's convenience.

• Journal of Microbiology and Biotechnology
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• v.25 no.7
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• pp.1136-1145
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• 2015

The diverse microbial communities that colonize distinct segments of the gastrointestinal tract are intimately related to aspects of physiology and the pathology of human health. However, most recent studies have focused on the rectal or fecal microbiota, and the microbial signature of the duodenum is poorly studied. In this study, we compared the microbiota in duodenal and rectal samples to illustrate the characteristic microbial signatures of the duodenum in healthy adults. Nine healthy volunteers donated biopsies and luminal contents from the duodenum and rectum. To determine the composition and diversity of the microbiota, 454-pyrosequencing of bacterial 16S rRNA was performed and multiple bioinformatics analyses were applied. The α-diversity and phylogenetic diversity of the microbiota in the duodenal samples were higher than those of the rectal samples. There was higher biodiversity among the microbiota isolated from rectal biopsies than feces. Proteobacteria were more highly represented in the duodenum than in the rectum, both in the biopsies and in the luminal contents from the healthy volunteers (38.7% versus 12.5%, 33.2% versus 5.0%, respectively). Acinetobacter and Prevotella were dominant in the duodenum, whereas Bacteroides and Prevotella were dominant in the rectum. Additionally, the percentage of OTUs shared in biopsy groups was far higher than in the luminal group (43.0% versus 26.8%) and a greater number of genera was shared among the biopsies than the luminal contents. Duodenal samples demonstrated greater biological diversity and possessed a unique microbial signature compared with the rectum. The mucosa-associated microbiota was more relatively conserved than luminal samples.

• Bulletin of the Korean Chemical Society
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• v.35 no.9
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• pp.2630-2634
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• 2014

The surface of natural graphite was modified by the use of hydrogen peroxide and evaluated as an anode material for lithium ion capacitors (LICs). The surface treatment was carried out under various ultrasonic conditions of 200, 300, and 400W, which were applied to a mixture of natural graphite and hydrogen peroxide solution for 1 h. While the bulk structure was maintained, the hexagonal symmetry and physical properties of natural graphite, such as BET surface area, tap density, and particle size, were affected by the surface treatment. FT-IR and XPS measurements confirmed the signature of C=O on the surface of graphite samples after treatment. Both the pristine and surface-treated graphites showed a similar reversible capacity of $370mAhg^{-1}$, and the coulombic efficiency of surface-treated graphite decreased with higher ultrasonic energies (89.1%, 89.0%, and 88.0% for 200, 300, and 400 W) comparing with pristine graphite (89.4%). The capacity retention of LICs was greatly improved with the treated natural graphite. The graphite treated under the ultrasonic energy of 300 W and pristine natural graphite showed capacity retention of 77.5% and 42.9%, implying that the surface treatment was an effective method for the improvement of natural graphite as an anode material for LICs.

• Journal of Applied Biological Chemistry
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• v.58 no.4
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• pp.355-361
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• 2015

The rice protein profiles of Oryza sativa L (Koshihikari) grown under organic and conventional cultivation regimes were compared on 2-D gels to develop diagnostic marker proteins for organic rice. The selected proteins, differentially expressed between organic and conventional rice, were compared with the differentially expressed proteins of another organic and conventional rice pairing, produced at a different location. In the first comparison among conventional, no-chemical, and organic rice grown in the same region, Korea, 13 proteins exhibiting differential expression in organic and conventionally grown plants were selected. Eight of the 13 proteins were down-regulated, and the 5 remaining proteins were up-regulated from conventional to organic rice. The second comparison pairing from Kyungju, revealed 12 differentially expressed proteins, with 8 down-regulated and 4 up-regulated proteins. Ten of the differentially expressed proteins that overlapped between the two comparison sets could not be clustered into any functional group using a functional annotation clustering tool. Further comparisons using another set of conventional and organic rice, belonging to a different variety of Oryza sativa L and produced in Sanchung, revealed 8 differentially expressed proteins, 5 of which were down-regulated and 3 of which were upregulated in the organic rice. Overall, 3 differentially expressed proteins were commonly found in all three organic rice crops. These 3 proteins, along with other overlapping differentially expressed proteins, can provide a good starting point for the development of signature proteins that can be used for the authentication of organic rice with a follow-up studies with more comparison sets.

• Korean Journal of Microbiology
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• v.41 no.2
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• pp.125-128
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• 2005

A 16S ribosomal RNA gene from S. chungbukensis DJ77 has been sequenced. This sequence had a length of 1,502 bp and was extended for 29 bp at 5' and for 37 bp at 3' from the partial sequence (1,435 bp) registered in 2000 year. Besides, 1 bp was newly added near to the 3' end. We made the secondary structure of the 16S rRNA based on E. coli model and found four specific regions. We found constant and variable regions in genus Sphingomonas as the result of multiple alignment of 16S rRNA gene sequences from Sphingomonas spp. and S. chungbukensis DJ77. We found a stem loop structure in S. chungbukensis DJ77, which was only discovered in C. jejuni to date. It showed the structural agreement despite the difference of the sequences from the both organisms. Finally, S. chungbukensis DJ77 belonged to cluster II (Sphingobium) group, after the classification using phylogenetic analysis and nucleotide signature analysis.

• Journal of Digital Convergence
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• v.15 no.8
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• pp.183-193
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• 2017

Digital accredited certificates issued under the Digital Signature Act provide essential functionalities for online service, so certificates are used for various services such as online banking, e-government. However, certificates can be stolen by hackers and users need to install separate software to use certificates. Recently FIDO, which aims to solve the problems of password-based authentication and the lack of interoperability between authentication methods, is used for biometric authentication and TrustZone, hardware-based secure environment, is used for safe smartphone usage. In this paper, the new service method is suggested which uses FIDO-based biometric authentication and stores certificates in TrustZone. This method can not only improve security and convenience but also be easily applied to the service because it uses built-in functionalities of new smartphones such as biometric sensors and TrustZone. It is expected that people can use certificates in a safe and convenient way with this method.