• The Korean Journal of Applied Statistics
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• v.35 no.2
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• pp.189-201
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• 2022

In this study, we propose factor augmentation to improve forecasting power of cryptocurrency return. We consider financial and economic variables as well as psychological aspect for possible factors. To be more specific, financial and economic factors are obtained by applying principal factor analysis. Psychological factor is summarized by news sentiment analysis. We also visualize such factors through impulse response analysis. In the modeling perspective, we consider ARIMAX as the classical model, and random forest and deep learning to accommodate nonlinear features. As a result, we show that factor augmentation reduces prediction error and the GRU performed the best amongst all models considered.

• The Science & Technology
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• v.19 no.1 s.200
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• pp.48-57
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• 1986

- DATA파이프 - 화학품 생산을 위한 바이오매스의 이용 - 선형 프로그래밍 산법 - 복합질병을 위한 왁찐 - 말라리아 왁찐 - 데이터 기록용의 확장식 디스크매체 - 생세포의 냉동보존용 전산화 시각분석법 - 콜버그완 - 중유회수의 능률향상 - 충돌 들뜸체계이용 소프트 X선 레이저 - 스터얼링 사이클 저온 냉각기 - 셀데인 - 플라즈마 체계이용 소프트 X선 레이저 - 수력터빈 시스템 - 암호시스템을 해독하는 산법 - 균일한 크기의 극히 미세한 물질을 형성하는 공정 - 마그네켄치 - 리그닌 퇴화효소 - 코즈믹 튜브 - 테라비트 Km/Sec용량의 광전송 - 폴리머-세라믹 복합체 - 노바 - 살아있는 뇌의 신경 수용체를 보고 측정하는 방법

• Proceedings of the IEEK Conference
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• 2001.06b
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• pp.71-74
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• 2001

Optical visual cryptography was proposed by conjunction of the optical theory with the cryptography. However, it had some difficulties. The problems occurred in the process of transferring data processing system from visual to optics. Therefore, it is appropriate to approach these problems in terms of optics. The results show that the optical visual cryptography system has both the effectiveness and reliability as well as real-time implementation property.

• Proceedings of the Optical Society of Korea Conference
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• 2000.08a
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• pp.126-127
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• 2000

In this paper, we proposed an optical encryption method based in the concept of visual cryptography and interferometry. In our method a secret binary image was divided into two sub-images and they were encrypted by 'XOR' operation with a random key mask. Finally each encrypted image was changed into phase mask. By interference of these two phase masks the original image was obtained. Compared with general visual encryption method, this optical method had good signal-to-noise ratio due to no need to generate sub-pixels like visual encryption.

• Journal of the Korea Convergence Society
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• v.11 no.3
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• pp.45-52
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• 2020

In this study, we propose a new Relative position pattern unlocking solution based on blind interaction, which is a new unlocking method, and compared it with existing unlocking methods to verify usability and security improvement. And verified the practical value of the proposed new unlocking solution. The relative position pattern unlock method is easily remembered than the numeric code method and is worth practical enough to show a degree of learning ease similar to the drawing pattern method. The new method is safer to steal than other two methods. It can be manufactured at a low cost and can also be used by special users such as blind people. Therefore, the practical value is relatively high.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.253-256
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• 2003

정보화 사회는 컴퓨터 기술의 발전과 통신 사용자의 증가로 인터넷 기반 디지털 데이터 전송 기술과 사용이 대폭 늘어나면서 디지털 데이터의 저작권 보호에 대한 필요성이 대두되고 있으며, 최근 디지털 워터마킹에 관한 많은 연구가 이루어지고 있다. 이러한 이미지에 대한 저작권 보호를 위해서는 이미지의 내용 인증과 소유권 인증, 불법 복제 등을 확인 할 수 있는 인증 기술이 요구된다 눈에 띄지 않는 암호인 디지털 워터마킹을 이미지에 삽입하는 기술로 이미지의 투명성과 견고성을 제공해야 하며, 이를 위해 정교한 인지 정보가 워터마킹 처리에 사용되어야 한다. 본 논문에서는 인간 중심의 시각 시스템의 관점에서 주파수 기반의 웨이브릿 변환을 통한 저작권 보호와 인증과 위조 방지에 대한 워터마킹을 제안한다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.10 no.3
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• pp.37-48
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• 2000

서울Visual cryptography scheme is a simple method in which can be directly decoded the secret information in human visual system without performing any cryptographic computations. This scheme is a kind of secret sharing scheme in which if a secret of image type is scattered to n random images(slides) and any threshold (or more) of them are stacked together the original image will become visible. In this paper we consider (2, n) visual cryptography scheme and propose a new construction method in which the number of expanded pixels can be reduced by using the sample matrix. The proposed scheme can futhermore distribute the multiple secret image to each group according to the difference of relative contrast.

• Journal of the Korea Convergence Society
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• v.5 no.4
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• pp.101-106
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• 2014

Most peoples are used to prefer to view the video contents rather than the other contents since the video contents are more easy to understand with both their eyes and ears. As the wide spread use of smartphones, the demands for the contents services are increasing rapidly. To promote the contents business, it's important to provide security of subscriber authentication and corresponding communication channels through which the contents are delivered. Generally, symmetric key encryption scheme is used to protect the contents in the channel, and the session key should be upadated periodically for the security reasons. In addition, to protect viewing paid contents by illegal users, the proxy authentication should not be allowed. In this paper, we propose biometric based user authentication and one time key generation models. The proposed model is consist of biometric template registration, session key generation and chanel encryption steps. We analyze the difference and benefits of our model with existing CAS models which are made for CATV contents protection, and also provides applications of our model in electronic commerce area.

• KNOM Review
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• v.21 no.2
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• pp.18-25
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• 2018

Since the development of block-chain technology by Satoshi Nakamoto and Bitcoin pioneered a new cryptocurrency market, a number of scale of cryptocurrency have emerged. There are crimes taking place using the anonymity and vulnerabilities of block-chain technology, and many studies are underway to improve vulnerability and prevent crime. However, they are not enough to detect users who commit crimes. Therefore, it is very important to detect abnormal behavior such as money laundering and stealing cryptocurrency from the network. In this paper, the characteristics of the transactions and user graphs in the Bitcoin network are collected and statistical information is extracted from them and presented as plots on the log scale. Finally, we analyze visualized plots according to the Densification Power Law and Power Law Degree, as a result, present features appropriate for detection of anomalies involving abnormal transactions and abnormal users in the Bitcoin network.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.4
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• pp.470-485
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• 2003

The steganography is one of methods that users can hide data. Some steganography softwares use audio data among multimedia data. However, these commercialized audio steganography softwares have disadvantages that the existence of hidden messages can or easily recognized visually and only certain-sized data can be hidden. To solve these problems, this study suggested, designed and implemented Dynamic Message Embedding (DME) algorithm. Also, to improve the security level of the secret message, the file encryption algorithm has been applied. Through these, StegoWaveK system that performs audio steganography was designed and implemented. Then, the suggested system and the commercialized audio steganography system were compared and analyzed on criteria of the Human Visilable System (HVS), Human Auditory System (HAS), Statistical Analysis (SA), and Audio Measurement (AM).