• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.84-94
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• 2021

Graph databases have been developed to efficiently store and query graph data composed of vertices and edges to express relationships between objects. Since the query types of graph database show very different characteristics from traditional NoSQL databases, benchmarking tools suitable for graph databases to verify the performance of the graph database are needed. In this paper, we propose an efficient graph database benchmarking system that supports diversity in graph inputs and queries. The proposed system utilizes OrientDB to conduct benchmarking for graph databases. In order to support the diversity of input graphs and query graphs, we use LDBC that is an existing graph data generation tool. We demonstrate the feasibility and effectiveness of the proposed scheme through analysis of benchmarking results. As a result of performance evaluation, it has been shown that the proposed system can generate customizable synthetic graph data, and benchmarking can be performed based on the generated graph data.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.29 no.4
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• pp.885-895
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• 2019

As seen in recent cases of hacking in financial services, attackers are attempting to hacking trustee with poor security management, rather than directly hacking a financial company. As a result, the consignor is strengthening the security check and control of the trustee, but small trustee has difficulties to invest in information security with the lack of computer facilities and the excessive cost of security equipment. In this paper I investigate the vulnerability of personal information processing life cycle standards in order to enhance the security of small consignee that receive personal information form the credit card company. To solve the vulnerability the company should use litigation management system constructed on cloud computing service and install VPN to secure confidentiality and intergrity in data transfer section. Also, to enhance the security of users, it is suggested to protect personal credit information by installing PC firewall and output security on user PC.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.631-636
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• 2019

In recently, various kinds of services utilizing the location information of the user's smart phone have appeared. Based on this trend, we designed a new type of learning assistant system that utilizes geofencing technology, which is a field of location information technology. This system identifies the location of the classroom using the location information of learner's the smart phone and automatically provides the necessary learning contents to the learner's smart phone when the learner enters the classroom set as the virtual fence area while carrying the smart phone respectively. Our system provides learning contents in a form similar to the form of a message or a mobile coupon and learners are used to such mobile service environments very much. So the use of learning contents provided by our system is expected to help improve the learning effect of learners.

• The Journal of the Korea Contents Association
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• v.19 no.2
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• pp.88-98
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• 2019

As the 2015 revised curriculum is being implemented from 2018, efforts are being made to cultivate scientific literacy among students in the field of science. Scientific experiments help students to develop their interest in Science and their scientific attitudes. Learning through experimentation rather than learning scientific facts increases learners' understanding, and can be remembered longer. Therefore, experiments in Science subject are very important. However, in middle schools, scientific experiments are not performed due to the lack of time, budget and experimental material. In this research, we analyze middle school science textbooks, conduct questionnaires for students of science pre-service teachers, select the most important science experiments, and develop a mobile App to simulate and experience scientific experiments with the App. The proposed App is developed in a game format using quest-based learning methods to gain learning enhancement. It is also made using Unity. In this paper, after developing the app, we propose the direction of STEAM contents development through analyzing the difference from existing apps and the feedback from users.

• Journal of Broadcast Engineering
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• v.23 no.6
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• pp.914-924
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• 2018

In this paper, we implement an Android application for infant language education using marker-based augmented reality. Combining animal word markers (noun), size/color word markers (adjective), and action word markers (verb) in puzzle form to make a simple sentence, the application shows virtual contents related to the content of the sentence. For example, when an animal marker is showed up on a camera, the corresponding animal appears. Additionally, when the motion markers are combined, the animal's appearance changes into an animation in which it acts. When a user touched a marker, user can hear the sound of the word, which gives an auditory effect, and by adding the rotation function, user can see the animation in any direction. Our goal is to increase infants' interest in learning language and also increase the effectiveness of education on the meaning of words and the structure of simple sentences, by encouraging them to actively participate in language learning through visual and auditory stimuli.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.8
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• pp.1015-1021
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• 2020

Mobile news users want news articles without advertising, meanwhile the news providers require advertisement displays in several types to attain advertising revenue. In this paper, we classified the types of advertisements on mobile news articles into fixed article type which is fixed on some areas of articles, fixed screen type which is fixed on mobile screens, and a combination type of them. In addition, we proposed a smart solution based on overlapping method which effectively organize advertisements to not distract the readers. The proposed method is similar to fixed article type and overlapping technique of advertisements on news article's photo or virtual area. The performance evaluation result shows that the proposed method provides more spaces for news articles effectively than the existing methods. Although only some areas of advertisements may be blocked according to the number or size of advertisements, the effect is not critical.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.30 no.6
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• pp.1031-1041
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• 2020

Cloud computing technology plays an important role in the deep learning industry as deep learning services are deployed frequently on top of cloud infrastructures. In such cloud environment, virtualization technology provides logically independent and isolated computing space for each tenant. However, recent studies demonstrate that by leveraging vulnerabilities of virtualization techniques and shared processor architectures in the cloud system, various side-channels can be established between cloud tenants. In this paper, we propose a novel attack scenario that can steal internal information of deep learning models by exploiting the Meltdown vulnerability in a multi-tenant system environment. On the basis of our experiment, the proposed attack method could extract internal information of a TensorFlow deep-learning service with 92.875% accuracy and 1.325kB/s extraction speed.

• The Journal of the Convergence on Culture Technology
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• v.8 no.1
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• pp.583-590
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• 2022

With the release of the Bitcoin source in 2009, cryptocurrencies are continuously developing and expanding the market. Recently, new applicability is expanding centered on NFT coin and metaverse payment service. In particular, the Central Cryptocurrency Exchange actively supports relay transactions between cryptocurrencies or between traditional fiat currencies and cryptocurrencies. The cryptocurrency trading market based on such a central exchange encouraged speculative factors of cryptocurrencies, strongly arousing speculation and futility of cryptocurrencies. In addition, the central cryptocurrency exchange induces the centralization of users and virtual assets, thereby hindering the decentralization and security enhancement strategies of the block chain. Therefore, this study describes the current status and problems of centrally controlled centralized cryptocurrency exchanges in service, and presents a distributed cryptocurrency exchange modeling strategy and major issues as a decentralization model of the exchange. This research can strengthen the anonymity, decentralization, and autonomy of cryptocurrency based on blockchain.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.4
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• pp.127-132
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• 2022

An anonymous encrypted communication networks that make it difficult to identify the trace of a user's access by passing through several virtual computers and/or networks, such as Tor, provides user and data privacy in the process of Internet communications. However, when it comes to abuse for inappropriate purposes, such as sharing of illegal contents, arms trade, etc. through such anonymous encrypted communication networks, it is difficult to detect and take appropriate countermeasures. In this paper, by extending the website fingerprinting technique that can identify access to a specific site even in anonymous encrypted communication, a method for specifying and classifying service types of websites for not only well-known sites but also unknown sites is proposed. This approach can be used to identify hidden sites that can be used for malicious purposes.

• Journal of Korea Society of Industrial Information Systems
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• v.27 no.2
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• pp.1-10
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• 2022

Deception technology is an extended concept of honeypot, which detects, prevents or delays attacks by deceiving adversaries. It has been applied to various system components such as network ports, services, processes, system calls and database management systems. We can apply the same concept to attacks on files. A representative example of a file attack is ransomware. Ransomware is a type of malware that encrypts user files and ask for ransom to recover those files. Another example is the wiper attack, which erases all or target files of a system. In this paper we propose a defense mechanism against these kinds of attacks by hiding files. Compared to backup or virtualization techniques, the proposed method incurs less space and performance overheads.