• Journal of the Korea Institute of Information Security & Cryptology
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• v.5 no.1
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• pp.3-16
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• 1995

In this paper, we deal with the cryptographic properties of Boolean functions generated by recursively extended methods from the points of balancedness, nonlinearity and correlation properties. First, we propose a new concept 'Strict Uncorrelated Criterion(SUC)' for two Boolean functions as a necessary condition for constructing Boolean functions of S-box which can be guaranteed to be resistant against Differential cryptanalysis, then we show that the recurively extended Boolean functions with particular form preserve the SUC. We also examine the correlation properties of Boolean functions using Walsh-Hadamard transformations and apply them to discuss nonlinearity, correlation properties and SUC of semi-bent function which is defined over odd dimensional vector space. Finally, we compare semi-bent function with Boolean functions which are generated by other similar recursive methods.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.21 no.4
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• pp.47-60
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• 2011

With the increase in the use of mobile banking service, mobile banking has become an attractive target to attackers. Even though many security measures are applied to the current mobile banking service, some threats such as physical theft or penetration to a mobile device from remote side are still remained as unsolved. With aiming to fill this void, we propose a novel approach to prevent e-financial incidents by analyzing mobile device user's input patterns. This approach helps us to distinguish between original user's usage and attacker's usage through analyzing personal input patterns such as input time-interval, finger pressure level on the touch screen. Our proposed method shows high accuracy, and is effective to prevent the e-finance incidents proactively.

• The Journal of Bigdata
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• v.5 no.2
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• pp.43-52
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• 2020

With the development of data technology, storing and sharing of data has increased, resulting in privacy invasion. Although de-identification technology has been introduced to solve this problem, it has been proved many times that identifying individuals using de-identified data is possible. Even if it cannot be completely safe, sufficient de-identification is necessary. But current laws and regulations do not quantitatively specify the degree of how much de-identification should be performed. In this paper, we propose an appropriate de-identification criterion considering the time required for re-identification. We focused on the case of using the k-anonymity model among various privacy models. We analyzed the time taken to re-identify data according to the change in the k value. We used a re-identification method based on linkability. As a result of the analysis, we determined which k value is appropriate. If the generalized model can be developed by results of this paper, the model can be used to define the appropriate level of de-identification in various laws and regulations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.469-474
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• 2020

This study explains the characteristics of micro-insurance based on the theoretical model of health insurance, such as the low demand of low-income people and the lower demand of higher risk aversion. In particular, these characteristics contradict the existing insurance theory which states that the lower the income, the higher the risk aversion, and the higher the demand for insurance. This study postulates a two-period model focusing on health insurance, contrary to a one-period model assumed in existing studies. As a result, first, we show that the decrease in income leads to a decrease in the preventive effort for illness. Second, we offer a model for micro-insurance in which the individual chooses a partial insurance under an actuarially fair insurance premium, while full insurance is optimal in existing studies. Third, we also show that the insurance demand decreases when the outlook for the future improves. Fourth, we finally show that the lack of trust and default risk of the insurer decrease the insurance demand as risk aversion increases.

• KIPS Transactions on Computer and Communication Systems
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• v.10 no.8
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• pp.231-234
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• 2021

Various problems arise as applications using locations increase. In order to solve this problem, related works are being conducted to protect the location of users. A fundamental reason for this problem is that users must provide their location information to the service provider (server) to receive the service. To improve these problems, there are works such as generating cloaking regions or generating dummies around them. However, if a user periodically asks the server for queries, the user's trajectory may be exposed by time zone. To improve this problem, in this paper, we propose a k-Anonymity Trajectory (k-ATY) technique that can improve the exposure probability of the trajectory even if the user requests continuous queries. Experimental results demonstrated the superiority of the proposed technique.

• Journal of Space Technology and Applications
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• v.2 no.2
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• pp.121-136
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• 2022

Automatic Identification System used in ship communication is required for marine control way, including monitoring of vessel operation in coastal and exchanging of information for safety navigation between them. But, it uses a very high frequency band of approximately 160 MHz, and at the same time, due to the curvature of Earth, there is a limit to the communication distance. Several demonstrations were made successfully over satellite, but not much work has been done yet through cube-satellite which has low-orbit at 500 km altitude. Here, we demonstrate a reception test of AIS (automatic identification system) receiver for a cube-satellites using software-defined radio (SDR). We collected AIS data from ship at port of Busan, Korea, using R8202T2 SDR and established to transmit them using Adam-Pluto and Matlab Simulink. The process of weakening the signal strength to a satellite was constructed using attenuator. Through above process, we demonstrated whether AIS data was successfully received from the AIS payload.

• Journal of Industrial Convergence
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• v.20 no.10
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• pp.17-24
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• 2022

Lora, a non-band network technology of the long-distance wireless standard LPWAN standard, uses ABP and OTTA methods and AES-128-based encryption algorithm (shared key) for internal terminal authentication and integrity verification. Lora's recent firmware tampering vulnerability and shared-key encryption algorithm structure make it difficult to defend against MITM attacks. In this study, the consensus algorithm(PBFT) is applied to the Lora network to enhance safety. It performs authentication and PBFT block chain creation by searching for node groups using the GPS module. As a result of the performance analysis, we established a new Lora trust network and proved that the latency of the consensus algorithm was improved. This study is a 4th industry convergence study and is intended to help improve the security technology of Lora devices in the future.

• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.669-676
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• 2022

Non-fungible tokens (NFTs) have the advantage of being able to reliably manage details after minting, but how can ideas be protected before being converted to NFTs? The use of NFTs to increase the value of digital assets is increasing, but the problem of creating and selling NFTs without the consent of the creator is also increasing. Existing methods for protecting creators include a method of using a traditional authentication system and a method of using a social network, but each has limitations. Therefore, in this study, an identity token utilization method is proposed as a way to supplement the existing limitations. When an identity token is used, a certified NFT is issued through an existing identity authentication authority, so the verification of the authenticity of the token becomes clear. In addition, in inheritance and transfer, it becomes possible to respond to legal problems related to the transfer of creative rights.

• The Korean Journal of Archival Studies
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• no.75
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• pp.249-297
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• 2023

This paper is a study on the reading records in archives. This study views it from a different standpoint. Archivists can deal with reading service as narrative practices. Theater is the main motive of this study. Theater plan of archival services is a trial of narrative practices in archives. The main focus of this study is how to manage the archival theater in archives. Archivists can participate in the policies that will benefit society as a whole. The various readings in archives are acts of narrative practices. People have to get chance of reading records in archives.

• Applied Chemistry for Engineering
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• v.34 no.2
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• pp.106-110
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• 2023

Lignin is compatible with various polymeric materials and useful as a carbon precursor. In this work, carbon monolith films were produced from polyacrylonitrile (PAN)@lignin precursor films by a controlled carbonization cycle. In addition, their morphological features, electrical properties, and adsorption behavior were analyzed and compared with those of carbonized PAN films. The successful formation of PAN@lignin precursor was confirmed by Fourier-transform infrared (FT-IR) spectroscopy. SEM was used to examine the morphology of precursor and carbonized films, revealing that both precursor and carbonized films retained structural stability following carbonization. A trace of lignin in the carbonized films was also found. The pore structure of the carbonized PAN@lignin film was measured using the BET method, indicating the formation of fairly uniform pores. The electrical properties were also analyzed to obtain the Ohmic relation, which demonstrated that the electrical signal was influenced by incoming materials. Finally, the carbonized PAN@lignin films were useful as adsorbents to remove metal ions. This study provides important information for future initiatives in relevant research fields.