• Journal of the Korea Society of Computer and Information
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• v.9 no.4 s.32
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• pp.13-18
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• 2004

In this paper, we proposed a new digital watermarking technique. It uses frequency domain of discrete wavelet transform(DWT). watermarking technique is one of the most important tools for DRM(Digital Right Management) We proposed a new algorithm watermark insertion and detection. This technique cleats the watermark sequence using the edge image, spread spectrum technique and DWT. We tested the technique with various attacks. and found that it satisfies the watermarking evaluation criteria. Cox similarity measurement value is more than 6 on the Lena image and PSNR is more than 40dB on JPEG, Collusion. Clopping and Scatting. By the result, we proved that the new technique satisfies the requirement of Digital contents distribution, which are undeletablility tenacity, statistical undetectablility.

• Proceedings of the Korea Information Processing Society Conference
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• 2002.11b
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• pp.1107-1110
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• 2002

본 논문에서는 현재 컨텐츠에 대한 저작권보호 기술로 활발히 연구되고 있는 워터마킹 기술과 핑거프린팅 기술에 대해 알아보고 핑거프린팅 기술의 구현시 문제시 되고 있는 공모공격의 유형을 분석한다. 워터마킹 기술은 소유권주장이 목표인 반면 핑거프린팅 기술은 사용자인증을 목표로 하는 것이 다르다. 즉, 판매되는 컨텐츠에 구매자(사용자)의 정보를 워터마크로 삽입한 후 배포하고 후에 불법복제가 의심되는 컨텐츠에 대해 적법구매자의 워터마크를 추출하여 불법재분배를 증명한다. 이는 불법복제가 어느 구매자로부터 이루어졌는지의 추적이 가능하게 한다. 하지만 핑거프린팅 기술은 워터마킹 기술과는 다르게 구매자 정보를 워터마크로 사용하기 때문에 마크가 삽입된 컨텐츠마다 서로 다르다는 특징을 갖는다. 의도적인 공격자는 이 특성을 이용하여 여러개의 핑거프린팅된 컨텐츠를 공모(collusion)하여 워터마크를 제거하기 위한 다양한 공격(attack)을 가할 수 있다. 평균화(averaging)공격과 모자익(mosaiking)공격이 공모공격의 대표적인 방법으로, 본 논문에서는 이러한 공격유형을 분석하고 공모공격에 강인한 핑거프린팅 삽입/추출방법을 고찰한다.

• ETRI Journal
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• v.32 no.4
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• pp.512-519
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• 2010

A cooperative model is presented to enable sharing of the spectrum with secondary users. Compared with the optimal model and competitive model, the cooperative model could reach the maximum total profit for secondary users with better fairness. The cooperative model is built based on the Nash equilibrium. Then a conceding factor is introduced so that the total spectrum required from secondary users will decrease. It also results in a decrease in cost which the primary user charges to the secondary users. The optimum solution, which is the maximum total profit for the secondary users, is called the collusion state. It is possible that secondary users may leave the collusion state to pursue the maximum of individual profit. The stability of the algorithm is discussed by introducing a vindictive factor to inhabit the motive of deviation. In practice, the number of secondary users may change. Adaptive methods have been used to deal with the changing number of secondary users. Both the total profit and fairness are considered in the spectrum allocating. The shared spectrum is 11.3893 with a total profit of 65.2378 in the competitive model. In the cooperative model, the shared spectrum is 8.5856 with the total profit of 73.4963. The numerical results reveal the effectiveness of the cooperative model.

• The KIPS Transactions:PartC
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• v.19C no.1
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• pp.63-70
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• 2012

To ensure privacy of individual information in remote healthcare service, health data should be protected through a secure technology such as encryption scheme. Only user who delegated decryption right can access to sensitive health data and delegator needs capability for revocating access privilege. Recently, in ubiquitous environment, CP-ABTD(Ciphertext-Policy Attribute-Based Threshold Decryption with Flexible Delegation and Revocation of User Attributes) which extends CP-ABE(Ciphertext-Policy Attribute-Based Encryption) has been proposed for these requirements. In this paper, we construct remote healthcare monitoring system with delegation and revocation capability for attribute in CP-ABTD. Finally, we analyze collusion attack between users in our system.

• Asia-Pacific Journal of Business
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• v.13 no.1
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• pp.213-230
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• 2022

Purpose - The purpose of this study is to find out any potential factors for explanatory variables when calculating the virtual successful bid rate in case of no collusion. Design/methodology/approach - An empirical analysis was conducted in this study with a regression analysis that included 725 bid samples under the public construction technical type bidding. Findings - The result of the basic analysis showed that there are several factors affecting the successful bid rate. First, collusion variable; second, government variable; third, successful bidder design score variable and the number of bidder variable among bidding features; fourth, turnkey variable based on the alternative method; fifth, civil works variable and plant works variable based on building work; sixth, asset variable and the fourth-quarter performance difference variable. However, the technical proposal method variable among bidding features was found to be statistically insignificant in column(4). Research implications or Originality - The significance of this research is that new variable such as the government variable and the fourth-quarter performance difference variable were added in the regression model, which showed statistically significant research results.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.4
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• pp.27-34
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• 2011

In this paper, it was presented a design on the dynamic multimedia fingerprinting code for anti-collusion code(ACC) in the protection of multimedia content. Multimedia fingerprinting code for the conventional ACC, is designed with a mathematical method to increase k to k+1 by transform from BIBD's an incidence matrix to a complement matrix. A codevector of the complement matrix is allowanced fingerprinting code to a user' authority and embedded into a content. In the proposed algorithm, the feature points were drawing from a content which user bought, with based on these to design the dynamical multimedia fingerprinting code. The candidate codes of ACC which satisfied BIBD's v and k+1 condition is registered in the codebook, and then a matrix is generated(Below that it calls "Rhee matrix") with ${\lambda}+1$ condition. In the experimental results, the codevector of Rhee matrix based on a feature point of the content is generated to exist k in the confidence interval at the significance level ($1-{\alpha}$). Euclidean distances between row and row and column and column each other of Rhee matrix is working out same k value as like the compliment matrices based on BIBD and Graph. Moreover, first row and column of Rhee matrix are an initial firing vector and to be a forensic mark of content protection. Because of the connection of the rest codevectors is reported in the codebook, when trace a colluded code, it isn't necessity to solve a correlation coefficient between original fingerprinting code and the colluded code but only search the codebook then a trace of the colluder is easy. Thus, the generated Rhee matrix in this paper has an excellent robustness and fidelity more than the mathematically generated matrix based on BIBD as ACC.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.46 no.1
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• pp.64-77
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• 2009

A proxy re-encryption scheme allows Alice to temporarily delegate the decryption rights to Bob via a proxy. Alice gives the proxy a re-encryption key so that the proxy can convert a ciphertext for Alice into the ciphertext for Bob. Recently, ID-based proxy re-encryption schemes are receiving considerable attention for a variety of applications such as distributed storage, DRM, and email-forwarding system. And a non-interactive identity-based proxy re-encryption scheme was proposed for achieving CCA-security by Green and Ateniese. In the paper, we show that the identity-based proxy re-encryption scheme is unfortunately vulnerable to a collusion attack. The collusion of a proxy and a malicious user enables two parties to derive other honest users' private keys and thereby decrypt ciphertexts intended for only the honest user. To solve this problem, we propose two ID-based proxy re-encryption scheme schemes, which are proved secure under CPA and CCA in the random oracle model. For achieving CCA-security, we present self-authentication tag based on short signature. Important features of proposed scheme is that ciphertext structure is preserved after the ciphertext is re-encrypted. Therefore it does not lead to ciphertext expansion. And there is no limitation on the number of re-encryption.

• Korean Journal of Labor Studies
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• v.19 no.1
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• pp.105-137
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• 2013

This paper proposes to examine the relationship between the two trade unions of Hyundai Motor Company (HMC) - those of the regular workers and of the in-house subcontract workers - around the issue of converting irregular workers to regular ones, which has been a social issue for a long time, and, furthermore, to find a desirable solution. The politics of the in-house subcontracting rotate around three axes: the conflictive collusion between the company and the regular workers'union regarding the internal labor market; the exclusion and resistance between the company and the subcontract workers'union; and the solidaristic conflict relationship between the two unions. After the final decree by the supreme court in 2012 the conflict and collusion/solidarity relationship of the three social actors have been amplified in scale - the continuous limping of the special bargaining between the company and the unions, the intensified conflict between the company and the subcontract workers'union, and the crisis of the collusion between the branches of the two unions are all evidence of this. A clue to the solution to the issues of in-house subcontracting in HMC can be found through reestablishment of the relationship among the three actors. In order to solve the in-house subcontracting issues in HMC, phased and lawful switching from irregular to regular positions, improvement of working conditions for the irregular workers, integration of the two unions (realization of 'one company one union'), and negotiated flexibility in the internal labor market will be required. Also to be considered are installation of a special committee for the issue, and utilization of external consultants. The result would be the possibility for the corporate labor market of HMC to be composed of regular workers, legal contract workers and directly-employed contract workers, which could be realized through bilateral relations of 'the labor and management conflict partnership'.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.73-76
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• 2003

디지털 핑거프린팅은 컨텐츠 유통 시, 구매자의 정보를 컨텐츠에 삽입함으로써 불법 유통 행위된 컨텐츠에 대하여 불법 배포자를 추적할 수 있는 기법이다. 이러한 핑거프린팅 코드는 워터마크 기술로서 컨텐츠내에 삽입되어 지고, 공모 공격(collusion attacks)등과 같이 불법적인 제거 공격으로부터 삽입된 정보가 안전하게 유지되어야 한다. 본 논문에서는 효율적이고 공모 공격에 강인한 핑거프린팅 코드를 구성하고, MPSK(M-ary Phase Shift Keying) 워터마킹 기술을 이용하여 안전하게 삽입, 추출하는 알고리즘을 제안한다. 제안 방법은 다양한 영상 데이터에 적용하여 공모 공격 및 기타 영상 처리에 대한 안전성을 확인하였다.

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.576-578
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• 2006

The wide use of digital media during the past few years, has led to an increase of digital piracy and tampering. To deal with these problems, the concept of digital fingerprinting has been introduced. Digital fingerprinting is an effective method to identify users who might try to redistribute multimedia content. In this paper, we propose new digital image fingerprinting techniques using watermark shifting scheme and concept of domain.