• Journal of Biomedical Engineering Research
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• v.39 no.2
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• pp.63-68
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• 2018

In modern society, speech recognition technology is emerging as an important technology for identification in electronic commerce, forensics, law enforcement, and other systems. In this study, we aim to develop an age classification algorithm for extracting only MFCC(Mel Frequency Cepstral Coefficient) expressing the characteristics of speech in Korean and applying it to deep learning technology. The algorithm for extracting the 13th order MFCC from Korean data and constructing a data set, and using the artificial intelligence algorithm, deep artificial neural network, to classify males in their 20s, 30s, and 50s, and females in their 20s, 40s, and 50s. finally, our model confirmed the classification accuracy of 78.6% and 71.9% for males and females, respectively.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.3
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• pp.585-594
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• 2015

As the storage market has been expanded due to growing data size, the research on various kinds of storages such as cloud, USB, and external HDD(Hard Disk Drive) has been conducted in digital forensic aspects. NAS(Network-Attached Storage) can store the data over one TB(Tera Byte) and it is well used for private storage as well as for enterprise, but there is almost no research on NAS. This paper selects three NAS products that has the highest market share in domestic and foreign market, and suggests the process and method for data acquisition in live NAS System.

• The KIPS Transactions:PartC
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• v.18C no.4
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• pp.217-226
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• 2011

As a diverse range of smartphones has been recently developed and diffused, the users of SNS (Social Network Service) also have been sharply increased. The SNS saves a variety of information such as exchanged pictures and videos, voice mails or location sharing, chat history, etc. as well as simple user data, so that the acquisition of data that are useful in the aspect of digital forensic is achievable. This thesis reviews the types of SNS that are available for the iPhone, a recent example of highly used smartphones, and types of data by each client. Also, efficient data analysis method for digital forensic investigations is suggested by analyzing the relationships within the collected data by each client.

• International Journal of Computer Science & Network Security
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• v.24 no.5
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• pp.79-88
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• 2024

The information retrieval domain deals with the retrieval of unstructured data such as text documents. Searching documents is a main component of the modern information retrieval system. Locality Sensitive Hashing (LSH) is one of the most popular methods used in searching for documents in a high-dimensional space. The main benefit of LSH is its theoretical guarantee of query accuracy in a multi-dimensional space. More enhancement can be achieved to LSH by adding a bit to its steps. In this paper, a new Dynamic Locality Sensitive Hashing (DLSH) algorithm is proposed as an improved version of the LSH algorithm, which relies on employing the hierarchal selection of LSH parameters (number of bands, number of shingles, and number of permutation lists) based on the similarity achieved by the algorithm to optimize searching accuracy and increasing its score. Using several tampered file structures, the technique was applied, and the performance is evaluated. In some circumstances, the accuracy of matching with DLSH exceeds 95% with the optimal parameter value selected for the number of bands, the number of shingles, and the number of permutations lists of the DLSH algorithm. The result makes DLSH algorithm suitable to be applied in many critical applications that depend on accurate searching such as forensics technology.

• Journal of the Korea Society of Computer and Information
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• v.12 no.3
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• pp.185-194
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• 2007

WiBro has become intentionally standardize as IEEE 802.16e. This WiBro service has been started by a portable internet at home as well as abroad. In this paper, an offender hacker do not direct attack on system on system that It marched an attack directly in damage system because a place oneself in mobile station of portable internet WiBro and avoid to attack hacker's system. At this time, a mobile make use of network inspection policy for back-tracking based on log data. Used network log audit, and presented TCP/IP bases at log bases as used algorithm, the SWT technique that used Thumbprint Algorithm. Timing based Algorithm, TCP Sequence number. Study of this paper applies algorithm to have been progressed more that have a speed to be fast so that is physical logical complexity of configuration of present Internet network supplements a large disadvantage, and confirm an effective back-tracking system. result of research of this paper contribute to realize a back-tracking technique in ubiquitous in WiBro internet network.

• KIPS Transactions on Software and Data Engineering
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• v.6 no.1
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• pp.15-22
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• 2017

With the advance of Internet Technology, various social network services are created and used by users. Especially, the use of smart devices makes that multimedia contents can be used and distributed on social network services. However, since the crime rate also is increased by users with illegal purposes, there are needs to protect contents and block illegal usage of contents with multimedia forensics. In this paper, we propose a multimedia forensic technique which is identifying the video source. First, the scheme to acquire the sensor pattern noise (SPN) using morphology filtering is presented, which comes from the imperfection of photon detector. Using this scheme, the SPN of reference videos from the reference device is estimated and the SPN of an unknown video is estimated. Then, the similarity between two SPNs is measured to identify whether the unknown video is acquired using the reference device. For the performance analysis of the proposed technique, 30 devices including DSLR camera, compact camera, camcorder, action cam and smart phone are tested and quantitatively analyzed. Based on the results, the proposed technique can achieve the 96% accuracy in identification.

• Journal of the Korea Society of Computer and Information
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• v.14 no.5
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• pp.149-156
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• 2009

Korean WiBro becomes international standard to IEEE 802.16e, and We are carrying out a WiBro network business from capital regions. We executed eavesdropping about voices and messenger program and the VoIP which frequently happened in WiBro networks at these papers. We have a lot in common with the Wireshark which is a packet collection and an analyzer, and We execute eavesdropping, and We reproduce eavesdropping data with bases to a SIP, H.263, TCP, UDP protocol through packets. In time of a copy of a packet negative the VoIP which verify time with bases, and was eavesdropped on integrity packet and a X-Lite call record, be matched that a packet is counterfeit forgery did not work, and We demonstrate, and verify integrity. The data which integrity was verified put in a seaming envelope, and we prepare so as it is to a liver of investigator, and execute, and to be able to do use to proof data after seaming in courts in order to utilize as criminal investigation data.

• Convergence Security Journal
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• v.23 no.5
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• pp.45-55
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• 2023

With the widespread use of digital devices, anonymous communication technologies such as the dark web and deep web are becoming increasingly popular for criminal activity. Because these technologies leave little local data on the device, they are difficult to track using conventional crime investigation techniques. The United States and the United Kingdom have enacted laws and developed systems to address this issue, but South Korea has not yet taken any significant steps. This paper proposes a new blockchain-based crime investigation method that uses physical memory data analysis to track the behavior of anonymous network users. The proposed method minimizes infringement of basic rights by only collecting physical memory data from the device of the suspected user and storing the tracking information on a blockchain, which is tamper-proof and transparent. The paper evaluates the effectiveness of the proposed method using a simulation environment and finds that it can track the behavior of dark website users with a residual rate of 77.2%.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.911-919
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• 2016

Compared to the past, the current disk storages have dramatically increased and extremely many data are transferred on the network everyday. In spite of the anticipation that such development will be continued, there have been lack of studies for improving the data-imaging time in terms of the digital forensics. In this paper, we firstly investigate the time due to hash functions during the data Imaging and secondly propose a method for improving the efficiency of the EWF-File imaging time from a cryptographic perspective.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.20 no.3
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• pp.79-91
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• 2010

In digital forensics, the creation time, last modified time, and last accessed time of a file or folder are important factors that can indicate events that have affected a computer system. The form of the time information varies with the file system, depending on the user's actions such as copy, transfer, or network transport of files. Specific changes of the time information may be of considerable help in analyzing the user's actions in the computer system. This paper analyzes changes in the time information of files and folders for different operations of the NTFS and attempts to reconstruct the user's actions.