• JOURNAL OF ELECTRICAL WORLD
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• s.262
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• pp.82-89
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• 1998

인터넷을 비롯하여 컴퓨터 네트워크와 통신의 급격한 발전으로 정보시큐리티의 중요성이 주목받고 있다. 정보시큐리티 대책의 기본은 기술적 대책에서부터 시작된다. 암호기술은 비밀 유지와 인증이라는 기본기능을 갖고 있으며, 직접적으로 정보를 지키는 일과 함께 다른 정보시큐리티기술의 요소로도 사용된다. 암호와 함께 사용되는 시큐리티기술로서 인간의 신체적 특징을 활용한 개인식별, 공공 공간과 중요시설 등의 대규모 범위에 대한 원격감시 그리고 이것들을 통합하는 응용시스템이 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10a
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• pp.796-798
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• 2001

본 논문에서는 벡터 양자화(Vector Quantization)를 이용해서 소유자의 저작물에 대해 저작권을 보호할 수 있는 디지털 워터마킹(Watermarking) 기법을 제안한다. 소유자의 워터마크 정보로는 사용자 정보를 비밀키를 이용해서 암호화한 데이터를 사용하며, 워터마킹 처리는 원본 이미지를 웨이블렛 기반의 벡터 양자화(Vector Quantization)에 사용되는 코드북(Coodbook)을 이용한다. 코드북을 사용함으로서 양질의 정보를 유지하면서 워터마킹을 효과적으로 처리할 수 있다.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.86-92
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• 2010

This paper proposes a new steganography scheme based on frequency domain using various image frames and collages that can protect the copyright of digital contents for users and securely perform to exchange the security information in the digital communication environments. The main idea of our proposed scheme is that the security informations related its copyright embed into the frequency domain of the image frame and collages when a user decorates the original image by using various image frames and collages. The strengths of our proposed scheme are as follows: (1) It allows to freely control the quantity of embedded information by changing the number of image frames and collages. (2) It is secure to variety image distortion attacks. (3) It maintains high PSNR(Peak Signal to Noise Ratio). As a result, the proposed steganography scheme can be used practically diverse multimedia security fields such as digital copyright protect, secure message communication and digital watermarking.

• The Journal of the Korea Contents Association
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• v.5 no.3
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• pp.83-91
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• 2005

The digital signature can be verified and disavowed only with cooperation of the signer in 'undeniable signature scheme. A signed confidential document of a company can be copied and delivered to a rival company. If a conventional signature scheme is used to sign the document, it can be confirmed as authentic by verifying the signature without the signer's cooperation. However, if the company doesn't want the document to be verified as authentic by the rival company, it is recommended to use the undeniable signature scheme. Convertible undeniable signature scheme has additional property that the signer can convert undeniable signature to the ordinary one. The document signed by undeniable signature scheme that is no longer confidential can be opened to public use by converting the signature to the ordinary one. In this study, the efficient multipurpose convertible undeniable signature scheme based on El-Gamal signature scheme is proposed. The proposed scheme satisfies undeniable property and can convert undeniable signature to the ordinary one. The number of public keys and signatures are less than those of Boyar's convertible signature scheme. It also reduces the number of communication steps of the signature confirmation protocol.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.2
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• pp.211-222
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• 2023

Multivariate quadratic equations (MQ)-based public-key cryptographic algorithms are one of promising post-quantumreplacements for currently used public-key cryptography. After selecting to NIST Post-Quantum Cryptography StandardizationRound 3 as one of digital signature finalists, Rainbow was cryptanalyzed by advanced algebraic attacks due to its multiple layered structure. The researches on MQ-based schemes are focusing on UOV with a single layer. In this paper, we propose a new MQ-signature scheme based on UOV using the combinations of the special structure of linear equations, spare polynomials and random polynomials to reduce the secret key size. Our scheme uses the block inversion method using half-sized blockmatrices to improve signing performance. We then provide security analysis, suggest secure parameters at three security levels and investigate their key sizes and signature sizes. Our scheme has the shortest signature length among post-quantumsignature schemes based on other hard problems and its secret key size is reduced by up to 97% compared to UOV.

• The Transactions of the Korea Information Processing Society
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• v.4 no.3
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• pp.659-669
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• 1997

Security as weel as consistency of data is very important issue in databaed security.This the serializability of transactions must be maintained and particularly covert channel not caesed between a high-level transaction and a low- level one.In this paper, we propose a secure transaction management algorithm using synamic version control] method that can slove disk space overhead to maintain multiversion and the problem that reansactions read too old versions when two versions are maintained.Disk space overhead can be sloved by properly cerating versions and synamically maintaining the number of versions and the problem for reading too old version can be solved by having transactions read versions as recent as possible.

• Journal of Korea Society of Industrial Information Systems
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• v.22 no.5
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• pp.9-15
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• 2017

In the Digital Age, All Data used in the Internet is Digitized and Transmitted and Received Over a Communications Network. Therefore, it is Important to Transmit Data with Confidentiality and Integrity, Since Digital Data may be Tampered with and Tampered by Illegal users. Steganography is an Efficient Method for Ensuring Confidentiality and Integrity Together with Encryption Techniques. I Propose a Hangul Steganography Method that Inserts a Secret Message based on a Changing Insertion Position and a Changing Eojeol Size in a Cover Medium. Considering the Insertion Capacity of 3.35% and the File Size Change of 0.4% in Hangul Text Steganography, Experimental Results Show that the Jaro_score Value needs to be Maintained at 0.946.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.3 no.4
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• pp.43-57
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• 2008

This study investigates the ethical standards of treasurers in the defense industry and explores ways to improve them in order to contribute to businesses' ethical managements. Also, this research examines how the ethical standards of the treasures have an influence on accounting transparency and accounting fraud. This paper deals with two fields, namely, ethical judgment and ethics in different cultures. The former focuses on actions that can occur in various ethical situations of accounting area. The latter shows that the development level of certified accountants’ ethical thinking depends on cultural difference.

• The Transactions of the Korea Information Processing Society
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• v.4 no.12
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• pp.3078-3087
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• 1997

The information security is very important in computer communication network, and the security system has been developed in many aspects to provide secure communication. The secret key distribution and mutual user authentication are essential element in designing security system, then many algorithms and implementation schemes have been proposed. But they don't consider communication protocol, so they are not easy to adapt a real communication network' In this paper, we propose a key distriburion and mutual user authentication scheme based on X.25 protocol which is the most popular in packet communication, and the proposed scheme maintains a protocol transparency and can select communication mode, so the security system is more capable.

• The Transactions of the Korea Information Processing Society
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• v.7 no.11
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• pp.3576-3583
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• 2000

Digital watermarks have recently been proposed for the purposes of copyright ptotechtion and autheutication for multimedia contents. A watermarking technique consists of an algorithm that incorporates a watermarking structure into an image in the spatial or frequency domains. In this paper we proposed a new watermarking method for authentication and integrity of digital images and the proposed algorithm uses the MD5 hash funiction and a symmetric key encryption algorithm. To decide the position of embedding watermark and the bit pasitionin the original image, the secret key is used as an input of the MD5 hash function. The simulation results show that the proposed algorithm has the advantage of difficulty to find positions of inserted watermarks, and keep the similar watermarked image quabty with Wong's method.