• Journal of KIISE:Information Networking
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• v.34 no.4
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• pp.246-255
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• 2007

Due to the bandwidth-consuming characteristics of the heavy-hitter P2P applications, it has become critical to have the capability of pinpointing and mitigating P2P traffic. Traditional port-based classification scheme is no more adequate for this purpose because of newer P2P applications, which incorporating port-hopping techniques or disguising themselves as HTTP-based Internet disk services. Alternatively, packet filtering scheme based on payload signatures suggests more practical and accurate solution for this problem. Moreover, it can be easily deployed on existing IDSes. However, it is significantly difficult to maintain up-to-date signatures of P2P applications. Hence, the automatic signature generation method is essential and will be useful for successful signature-based traffic identification. In this paper, we suggest an automatic signature generation method for Internet disk P2P applications and provide an experimental results on CNU campus network.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.4
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• pp.39-45
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• 2010

Because of portable storage device's technical improvement, it's speeding up the conversion of mass storage. It means it's easier to move and save data. Generally, USB is using for portable storage device and forensic perspective, it's possible us to study data drain through portable storage device under securement of using vestige of USB. If we can secure using vestige of USB from boot domain it's possible to investigate data drain & prove criminal act. This thesis is suggesting Key/Thumb drive & USB Drive Enclosure's confirmation of using or not and division way though Disk Signature analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.549-555
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• 2007

A digital signature scheme provides integrity of the document, authentication and non-repudiation of a signer. Usually the key for digital signature is stored in hard disk or removal disk storage. The drawback of this approach is that the signer can let the agent to sign instead of the signer by providing the key information. It can be abused in applications such as electronic election. In this paper, we propose the undeniable biometric digital multi-signature scheme suitable for applications where the signer should not make an agent sign instead of himself/herself. The undeniable multi-signature scheme requires many signers and only the designated user can confirm the authenticity of multi-signature. The proposed scheme satisfies undeniable property and it is secure against active attacks such as modification and denial of the multi-signature by signers. As the key is generated through the signer's fingerprint image, it's also secure against signing by an agent.

• Journal of KIISE:Databases
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• v.29 no.1
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• pp.79-88
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• 2002

Data on the Internet are usually represented and transfered as XML. the XML data is represented as a tree and therefore, object repositories are well-suited to store and query them due to their modeling power. XML queries are represented as regular path expressions and evaluated by traversing each object of the tree in object repositories. Several indexes are proposed to fast evaluate regular path expressions. However, in some cases they may not cover all possible paths because they require a great amount of disk space. In order to efficiently evaluate the queries in such cases, we propose an optimized traversing which combines the signature method and block traversing. The signature approach shrink the search space by using the signature information attached to each object, which hints the existence of a certain label in the sub-tree. The block traversing reduces disk I/O by early evaluating the reachable objects in a page. We conducted diverse experiments to show that the hybrid approach achieves a better performance than the other naive ones.

• The Transactions of the Korea Information Processing Society
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• v.3 no.4
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• pp.757-765
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• 1996

View index techniques are proposed to process queries on views. Signature referencing techniques keep pointers with signatures of the referred object when there is any reference relationship between objects. When queries having conditions on referred object are give, disk I/Os can be reduced by checking conditions using stored signatures. Signature view index techniques proposed in this paper apply signature referencing techniques to view index by keeping not only tuple identifiers but also signatures for the tuple. When queries having conditions on views regiven, we can retrieve only tuples from a view index which satisfy given conditions by checking those with stored signatures.

• The KIPS Transactions:PartD
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• v.9D no.1
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• pp.31-42
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• 2002

In this paper, we propose a new spatio-temporal representation scheme which can model moving objets trajectories effectively in video data and a new signature-based access method for moving objects trajectories which can support efficient retrieval on user query based on moving objects trajectories. The proposed spatio-temporal representation scheme supports content-based retrieval based on moving objects trajectories and concept-based retrieval based on concepts(semantics) which are acquired through the location information of moving objects trajectories. Also, compared with the sequential search, our signature-based access method can improve retrieval performance by reducing a large number of disk accesses because it access disk using only retrieved candidate signatures after it first scans all signatures and performs filtering before accessing the data file. Finally, we show the experimental results that proposed scheme is superior to the Li and Shan's scheme in terns of both retrieval effectiveness and efficiency.

• The KIPS Transactions:PartD
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• v.11D no.2
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• pp.247-258
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• 2004

Recently, there have been researches on storage and retrieval technique of moving objects, which are highly concerned by user in database application area such as video databases, spatio-temporal databases, and mobile databases. In this paper, we propose a new signature-based indexing scheme which supports similar sub-trajectory retrieval at well as good retrieval performance on moving objects trajectories. Our signature-based indexing scheme is classified into concatenated signature-based indexing scheme for similar sub-trajectory retrieval, entitled CISR scheme and superimposed signature-based indexing scheme for similar sub-trajectory retrieval, entitled SISR scheme according to generation method of trajectory signature based on trajectory data of moving object. Our indexing scheme can improve retrieval performance by reducing a large number of disk access on data file because it first scans all signatures and does filtering before accessing the data file. In addition, we can encourage retrieval efficiency by appling k-warping algorithm to measure the similarity between query trajectory and data trajectory. Final]y, we evaluate the performance on sequential scan method(SeqScan), CISR scheme, and SISR scheme in terms of data insertion time, retrieval time, and storage overhead. We show from our experimental results that both CISR scheme and SISR scheme are better than sequential scan in terms of retrieval performance and SISR scheme is especially superior to the CISR scheme.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.6
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• pp.1-9
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• 1994

Astorage structure using signatures is proposed to evaluate efficently queries including conditions of nested attributes in the nested relational databases This method stores a subrelation signature into the storage structure for a nested tuple with its subrelation pointer. During query processing steps, the subrelation signatures are matched first with the nested predicates in the query. When the match operation completes with success then physical retrieval of the subrelation occurrs resulting in reduction of disk 1/Os.

• The KIPS Transactions:PartD
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• v.11D no.1
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• pp.61-68
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• 2004

Now, the representative researching trends of view managements for improving the query processing in multi-database system are focused on the materialized view mechanism and the signature view index mechanism. But when we compare with both mechanisms, the former mechanism's access time is faster than one of the latter's, and needs large space. The latter mechanism needs small space and the access time is slower than one of the former. These mechanisms are trade-off each other. Therefore, in case of query process using the view management, we are to improve the system performance and to reduce the access cost of disk input and output by suggesting a new mechanism mixing both the materialized view mechanism and the signature view index mechanism. We suggested that the structure of metadata and the algorithm about the new mired mechanism.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.66.3-67
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• 2021

Low-mass stars form by the gravitational collapse of dense molecular cores. Observations and theories of low-mass protostars both suggest that accretion bursts happen in timescales of ~100 years with high accretion rates, so called episodic accretion. One mechanism that triggers accretion bursts is infalling fragments from the outer disk. Such fragmentation happens when the disk is massive enough, preferentially activated during the embedded phase of star formation (Class 0 and I). Most observations and models focus on the gas structure of the protostars undergoing episodic accretion. However, the dust and ice composition are poorly understood, but crucial to the chemical evolution through thermal and energetic processing via accretion burst. During the burst phase, the surrounding material is heated up, and the chemical compositions of gas and ice in the disk and envelope are altered by sublimation of icy molecules from grain surfaces. Such alterations leave imprints in the ice composition even when the temperature returns to the pre-burst level. Thus, chemical compositions of gas and ice retain the history of past bursts. Infrared spectral observations of the Spitzer and AKARI revealed a signature caused by substantial heating, toward many embedded protostars at the quiescent phase. We present the AKARI IRC 2.5-5.0 ㎛ spectra for embedded protostars to trace down the characteristics of accretion burst across the evolutionary stages. The ice compositions obtained from the absorption features therein are used as a clock to measure the timescale after the burst event, comparing the analyses of the gas component that traced the burst frequency using the different refreeze-out timescales. We discuss ice abundances, whose chemical change has been carved in the icy mantle, during the different timescales after the burst ends.