• Journal of The Korean Association of Information Education
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• v.1 no.1
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• pp.49-59
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• 1997

In this thesis, To provide the base of effective data access methods, performance of some indexing techniques used gent-Tally are compared. They are classified as primary key and multikey. For primary key method, made a comparative analysis on Static index. Dynamic index and Hashing. For multikey indexing method K-d tree, K-d-B tree, Inverted file and Grid file of which characteristics are compared. In many applications, multikey indexings are more requested, but are not supplied enough. So, to satisfy users' request - more fast, more exact and to be applied according to the trend of being huge database systems, it is requested more study about multikey data access methods.

• Proceedings of the Korea Information Assurance Society Conference
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• 2004.05a
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• pp.131-137
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• 2004

With the rapid development of information sharing through network, If system is exposed to various threatener and security incident are became a social problem. As a countermeasure, various security systems are been using such as IDS, Firewall, VPN etc.. But, expertise or expert is required to handle security system. In this paper, design and implementation of file access control module for secure operation system. The module, implemented in this paper, is based on Windows and has effect integrity and non-repudiation for a file.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.5
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• pp.155-160
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• 2018

In this paper, we found that buffer cache in general systems does not perform well in rendering software, and presented a new buffer cache management scheme that resolves this problem. To do so, we collected various file I/O traces of rending software and analyzed their characteristics. From this analysis, we observed that file I/Os in rendering consist of long loops, short loops, random accesses, and write-once accesses. Based on this observation, we presented a buffer cache management scheme that allocates cache space to each access types and manages them appropriately, thereby improving the buffer cache performances by 19% on average and up to 55%.

• The Transactions of the Korea Information Processing Society
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• v.2 no.2
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• pp.156-167
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• 1995

VDFS(V-kernel Distributed File System) constructed in this paper proposes an asymmetric Distributed File System so that various problems of existing symmetric structures like NFS ＆ RFS may be solved in small-sized system. Particulary, in this paper, server workload can be reduced by using a caching mechanism and remote access transparency can be improved by using a sharing file duplicately.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.6
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• pp.1289-1300
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• 2011

In recent computer systems with high-performance, users execute programs needing large memory and programs intensively accessing files simultaneously. Such a large memory requirement makes virtual memory systems access swap spaces in disk, and intensive file accesses require file systems to access file system partitions in disk. Executing the two kinds of programs at once incurs large disk seeks between swap spaces and file system partitions frequently. To solve the problem, this paper proposes a new scheme called SAF to create several swap spaces in a file system partition, where pages to be paged out are stored. When a page is paged out, the scheme stores the page to one of the swap spaces close to a disk location where the most recently accessed file is located. The chosen swap space in the file system partition is closer to the disk location than the traditional swap space, so that our scheme can reduce the large disk seek time spent to move to the traditional swap space in paging out a page. The experiment of our scheme implemented in FreeBSD 6.2 shows that SAF reduces the execution time of several benchmarks over FreeBSD ranging from 14% to 42%.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.337-345
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• 1999

The purpose of this study was to compare the shape of root canal after instrumentation with some engine driven NiTi files. Thirty narrow and curved canals(15-35 degree) of mesial canals of extracted human mandibular first molars were divided into three groups. Group 1: After radicular access with Gates Glidden drill, apical shaping using step back method with Flexo file Group 2: After radicular access with Gates Glidden drill, apical shaping with Profile .04 Group 3: Canal shaping with GT file and Profile .04. Using modified Bramante technique, the root was sectioned at 2 mm from apical foramen, height of curvature, 2 mm from canal orifice. Canal centering ratio, amount of transport, amount of dentin removed, shape of canal were measured and statistical analysis is done using SPSS Program V 7.5. The results were as follows: 1. Canal centering ratio of group 3 was the lowest at coronal part, but there was no statistical difference. Centering ratio of group 2 was the lowest at curve part, and there was statistical difference between group 1(P<0.05). Centering ratio of group 2 was the lowest at apical part, but there was no statistic difference. 2. Amount of transport of group 3 was the lowest at coronal part, but there was no statistical difference. Amount of transport of group 2 was the lowest at curve part, and there was statistical difference between group 1(P<0.05). Amount of transport of group 3 was the lowest at apical part, and there was statistical difference between group 1 and group 2, group 1 and group 3(P<0.05). 3. Amount of dentin removed of group 3 was the lowest at coronal part, bur there was no statistical difference. Amount of dentin removed of group 2 was the lowest at curve part, but there was no statistical difference. Amount of dentin removed or group 2 was the lowest at apical part, and there was statistical difference between group 1 and group 2, group 1 and group 3(P<0.05). 4. The shape of the canals after instrumentation varied among the groups. The majority of canals at coronal and curve part for group 1 were round in shape(7 in 10), those at apical part were oval(8 in 10). The majority of canals at coronal part for group 2 were round in shape(7 in 10) and there was no difference in the number of shape at other part. There was no difference in the number of shape at every part for group 3. As above results, NiTi rotary instrumentation showed a trend to remain more centered in the canal than SS file instrumentation. At using NiTi file, coronal shaping with Gates Glidden drill was not statistically different from shaping with GT file. But shaping with GT file showed tapered canals, so it may be said that shaping with GT file is a safe and valuable instrumentation method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.10
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• pp.1397-1402
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• 2021

The overlay2 file system is one of the union file systems that mounts multiple directories into one. The source directory used for this overlay2 file system mount has a characteristic that it operates independently of the write-able layer after mounting, so it is often used for container platforms for application delivery. However, the overlay2 file system has a security vulnerability that the write-able layer is also modified when file in the source directory is modified. In this study, I proposed the overlay2 file system protection technology to remove the security vulnerabilities of the overlay2 file system. As a result of empirically implementing the proposed overlay2 file system protection technology and verifying the function, the protection technology proposed in this study was verified to be effective. However, since the method proposed in this study is a passive protection method, a follow-up study is needed to automatically protect it at the operating system level.

• Journal of Information Processing Systems
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• v.17 no.4
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• pp.772-786
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• 2021

The process of tracking suspicious behavior manually on a system and gathering evidence are labor-intensive, variable, and experience-dependent. The system logs are the most important sources for evidences in this process. However, in the Microsoft Windows operating system, the action events are irregular and the log structure is difficult to audit. In this paper, we propose a model that overcomes these problems and efficiently analyzes Microsoft Windows logs. The proposed model extracts lists of both common and key events from the Microsoft Windows logs to determine detailed actions. In addition, we show an approach based on the proposed model applied to track illegal file access. The proposed approach employs three-step tracking templates using Elastic Stack as well as key-event, common-event lists and identify event lists, which enables visualization of the data for analysis. Using the three-step model, analysts can adjust the depth of their analysis.

• The KIPS Transactions:PartC
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• v.18C no.6
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• pp.369-378
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• 2011

To ensure data confidentiality and fine-grained access control in business environment, system model using KP-ABE(Key Policy-Attribute Based Encryption) and PRE(Proxy Re-Encryption) has been proposed recently. However, in previous study, data confidentiality has been effected by decryption right concentrated on cloud server. Also, Yu's work does not consider a access privilege management, so existing work become dangerous to collusion attack between malicious user and cloud server. To resolve this problem, we propose secure system model against collusion attack through dividing data file into header which is sent to privilege manager group and body which is sent to cloud server. And we construct the model of access privilege management using AONT based XOR threshold Secret Sharing, In addition, our scheme enable to grant weight for access privilege using XOR Share. In chapter 4, we differentiate existing scheme and proposed scheme.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.4B
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• pp.288-299
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• 2012

To ensure data confidentiality and fine-grained access control in business environment, system model using KP-ABE(Key Policy-Attribute Based Encryption) and PRE(Proxy Re-Encryption) has been proposed recently. However, in previous study, data confidentiality has been effected by decryption right concentrated on cloud server. Also, Yu's work does not consider a access privilege management, so existing work become dangerous to collusion attack between malicious user and cloud server. To resolve this problem, we propose secure system model against collusion attack through dividing data file into header which is sent to privilege manager group and body which is sent to cloud server and prevent modification attack for proxy re-encryption key using d Secret Sharing, We construct protocol model in medical environment.