• Convergence Security Journal
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• v.17 no.5
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• pp.35-40
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• 2017

The control system can have such threats as information leakage and falsification through various routes due to communications network fusion with public network. As the issues about security and the infringe cases by new attack methods are diversified recently, with the security system that makes information data database by simply blocking and checking it is difficult to cope with new types of threats. It is also difficult to respond security threats by insiders who have security access authority with the existing security equipment. To respond the threats by insiders, it is necessary to collect and analyze Event Log occurring in the internal system realtime. Therefore, this study could find out whether there is correlation of the elements among Event Logs through correlation analysis based on Event Logs that occur real time in the control system, and based on the analysis result, the study is expected to contribute to studies in this field.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.9
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• pp.2064-2072
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• 2015

To improve performance, most of Web Services produce and manage User Access Logs. Through the Access Logs, the record provides information about time when the most traffic happens and logs and which resource is mostly used. Then, the log can be used to analyze. However, in case of increasing high traffics of Web Services at the specific time, the performance of Web Service leads to deterioration because the number of processing User Access Logs is increasing rapidly. To solve this problem, we should improve the system performance, or tuning is needed, but it makes a problem cost a lot of money. Also, after it happens, it is not necessary to build such system by spending extra money. Therefore, this paper described the effective Web Service's performance as using improved User Access Log performance. Also, to process the newest data in bulk, this paper includes a method applying some parts of NoSQL using Redis.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.5
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• pp.74-82
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• 2011

SSD has a limitation of number of erase/write cycles and does not allow in-place update unlike the hard disk because SSD is composed of an array of NAND flash memory. Thus, FTL is used to effectively manage SSD of having different characteristics from traditional disk. FTL has page, block, log-block mapping method. Among then, when log-block mapping method such as BAST and FAST is used, the performance of SSD is degraded because frequent merge operations cause lots of pages to be copied and deleted. This paper proposes a data allocation and replacement method based on access frequency by allocating PRAM as checking area of access frequency, log blocks, storing region of hot data in SSD. The proposed method can enhance the performance and lifetime of SSD by storing cold data to flash memory and storing log blocks and frequently accessed data to PRAM and then reducing merge and erase operations. Besides, a data replacement method is used to increase utilization of PRAM which has limitation of capacity. The experimental results show that the ratio of erase operations of the proposed method is 46%, 38% smaller than those of BAST and FAST and the write performance of the proposed method is 34%, 19% higher than those of BAST and FAST, and the read performance of the proposed method is 5%, 3% higher than those of BAST and FAST, respectively.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.6
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• pp.267-273
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• 2011

The importance of networking capability is gaining more weight for enterprise business and high-speed Internet access with guaranteed security management is essential to companies. This paper presents a unified network security management solution to support high-speed Internet access, active security management, traffic classification and control. The presented system provides firewall, VPN, intrusion detection, contents filtering, traffic management, QoS management, and history log functions in unified manner implemented in a single appliance device located at the edge of enterprise networks. This will enable cost effective unified network security solution to companies.

• Journal of Korea Multimedia Society
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• v.24 no.1
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• pp.58-66
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• 2021

The user's password must be encrypted one-way through the hash function and stored in the database. Widely used hash functions such as MD5 and SHA-1 have also been found to have vulnerabilities, and hash functions that are considered safe can also have vulnerabilities over time. Salt enhances password security by adding it before or after the password before putting it to the hash function. In the case of the existing Salt, even if it is randomly assigned to each user, once it is assigned, it is a fixed value in a specific column of the database. If the database is exposed to an attacker, it poses a great threat to password cracking. In this paper, we suggest variable-dynamic Salt that dynamically changes according to the user's password during the login process. The variable-dynamic Salt can further enhance password security during login process by making it difficult to know what the Salt is, even if the database or source code is exposed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3237-3256
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• 2012

In the context of effective usage of a scarce spectrum resource, emerging wireless communication standards will demand spectrum sharing with existing systems as well as multiple access with higher spectral efficiency. We mathematically analyze the sum throughput of a spectrum sharing space-division multiple access (SDMA) system, which forms a transmit null in the direction of other coexisting systems while satisfying orthogonal beamforming constraints. For a large number of users N, the SDMA throughput scales as log N at high signal-to-noise ratio (SNR) ((J-1) loglog N at normal SNR), where J is the number of transmit antennas. This indicates that multiplexing gain of the spectrum sharing SDMA is $\frac{J-1}{J}$ times less than that of the non-spectrum sharing SDMA only using orthogonal beamforming, whereas no loss in multiuser diversity gain. Although the spectrum sharing SDMA always has lower throughput compared to the non-spectrum sharing SDMA in the non-coexistence scenario, it offers an intriguing opportunity to reuse spectrum already allocated to other coexisting systems.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.1
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• pp.34-39
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• 2007

According to the active use of internet the need for security in various environment is being emphasized. Moreover with the broad use of Messenger on PC and P2P applications. the security and management of individual hosts on internet became very important issues. Therefore in this paper we propose the design and implementation of a host based access control system for the hosts on internet including window based PC which provides access control, information on packets, and record and monitoring of log files.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.673-677
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• 2010

Recently, NAND flash memory has been widely used in embedded systems, personal computers, and server systems because of its attractive features, such as non-volatility, fast access speed, shock resistance, and low power consumption. Due to its hardware characteristics, specifically its 'erase-before-write' feature, Flash Translation Layer is required for using flash memory like hard disk drive. Many FTL schemes have been proposed, but conventional FTL schemes have problems such as block thrashing and block associativity problem. The KAST scheme tried to solve these problems by limiting the number of associations between data block and log block to K. But it has also block thrashing problem in random access I/O pattern. In this paper, we proposed a new FTL scheme, UDA-LBAST. Like KAST, the proposed scheme also limits the log block association, but does not limit data block association. So we could minimize the cost of merge operations, and reduce merge costs by using a new block reclaim scheme, log block garbage collection.

• Journal of Digital Contents Society
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• v.18 no.4
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• pp.747-751
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• 2017

The log has variable informations that are important and necessary to manage a network when accessed to network servers. These informations are used to reduce a cost and efficient manage a network through the meaningful prediction information extraction from the amount of user access. And, the network manager can instantly monitor the status of CPU, memory, disk usage ratio on network using the SNMP. In this paper, firstly, we have accumulated and analysed the 6 network logs and extracted the informations that used to predict the amount of user access. And then, we experimented the prediction simulation with the time series analysis such as moving average method and exponential smoothing. Secondly, we have simulated the usage ration of CPU, memory, and disk using Xian SNMP simulator and extracted the OID for the time series prediction of CPU, memory, and disk usage ration. And then, we presented the visual result of the variable experiments through the Excel and R programming language.

• Journal of KIISE:Software and Applications
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• v.30 no.9
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• pp.843-849
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• 2003

Web usage mining is the technique of data mining that analyzes web users' usage patterns by large web log. To use the web usage mining technique, we have to classify correctly users and users session in preprocessing, but can't classify them completely by only log files with standard web log format. To classify users and user session there are many problems like local cache, firewall, ISP, user privacy, cookey etc., but there isn't any definite method to solve the problems now. Especially local cache problem is the most difficult problem to classify user session which is used as input in web mining systems. In this paper we propose a heuristic method which solves local cache problem by using only click stream data of server side like referrer log, agent log and access log, classifies user sessions and completes session.