• Journal of the Korea Institute of Information Security & Cryptology
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• v.17 no.4
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• pp.131-136
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• 2007

Ad hoc networks enable efficient resource aggregation in decentralized manner, and are inherently scalable and fault-tolerant since they do not depend on any centralized authority. However, lack of a centralized authority prompts many security-related challenges. Moreover, the dynamic topology change in which network nodes frequently join and leave adds a further complication in designing effective and efficient security mechanism. Security services for ad hoc networks need to be provided in a scalable and fault-tolerant manner while allowing for membership change of network nodes. In this paper, we investigate distributed certification mechanisms using a threshold cryptography in a way that the functions of a CA(Certification Authority) are distributed into the network nodes themselves and certain number of nodes jointly issue public key certificates to future joining nodes. In the process, we summarize one interesting report [5] in which the recently proposed RSA-based ad hoc signature scheme, called URSA, contains unfortunate yet serious security flaws. We then propose new scheme by fixing their security flaws.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.5
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• pp.83-91
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• 2008

IISO/IEC 9594-8 defines the public key framework and attribute certificate framework. Attribute certificate framework deals with privilege management infrastructure(PMI). In PMI, for privilege management using attribute certificates, role assignment certificates and role specification certificates are used to assign and specify privileges independently. Role specification certificates includes privilege specifications and the details far privilege management of network environments. Privilege management of unreliable network environment tries to enhance the reliability and efficiency of privilege information transmission forwarding over unreliable routes in the presence of potentially faulty nodes and edges. Each node forms a role specification tree based on role specification relationship data collected from the network. In this paper privilege management cost with the role specification certificates tree structure is evaluated trying to reduce the overhead incurred by role creation and modification of privileges. The multicasting of packets are used for scalability. We establish management cost model taking into account the packet loss and node reliability which continuously join and leave for network. We present quantitative results which demonstrate the effectiveness of the proposed privilege management scheme.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.11 no.6
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• pp.41-51
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• 2001

Group signature schemes allow a group member to sign messages anonymously on behalf of the group. In case of dispute, only a designated group manager can reveal the identity of the member. During last decade, group signature schemes have been intensively investigated in the literature and applied to various applications. However, there has been no scheme properly handling the situation that a group member wants to leave a group or is excluded by a group manager. As noted in[3], the complexity of member deletion stands in the way of real world applications of group signatures and the member deletion problem has been a pressing open problem. In this paper we propose an efficient group signature scheme that allows member deletion. The length of the group public key and the size of signatures all independent of the size of the group and the security of the scheme relies on the RSA assumption. In addition, the method of tracing all signatures of a specific member is introduced.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.6
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• pp.93-112
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• 2002

Since the multicast group which is composed of various members is dynamic, members of the group frequently join or leave. So, for a new session, group keys are efficiently updated and distributed. In this paper, we describe very simple and new efficient logical key hierarchy(ELKH) protocol which is based on an one-way function. In the previous schemes, when the group controller distributes new created keys or updated keys to the members the information is usally encryted and then transmited over a multicast channel. But ELKH secretes the multicast message by using the one-way function and XOR operator instead of encrypting it. Hence our main construction improves the computational efficiency required from the group controller and group memebers while doesn't increase size of re-keying message when compared to $EHBT^{[12]}$. Assuming the security of an underlying one-way function, we prove that our scheme satisfies forward secrecy and backward secrecy.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.1
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• pp.57-65
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• 2012

People leave voicemails or record phone conversations in their daily cell phone use. Sometimes important voice data is deleted by the user accidently, or purposely to cover up criminal activity. In these cases, deleted voice data must be able to be recovered for forensics, since the voice data can be used as evidence in a criminal case. Because cell phones store data that is easily fragmented in flash memory, voice data recovery is very difficult. However, if there are identifiable patterns for the deleted voice data, we can recover a significant amount of it by researching images of it. There are several types of voice data, such as QCP, AMR, MP4, etc.. This study researches the data recovery solutions for EVRC codec and AMR codec in QCP file, Qualcumm's voice data format in cell phone.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.4
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• pp.719-731
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• 2012

One of the most important point in the Internet crime investigation is tracing back and pointing out a criminal host. However, criminals can forge a crime record stored in the crime host, or can utilize malicious applications in order not to leave a crime record. In addition, criminals can change the source IP address of a crime host and deny their involvement. In this study, we suggests the Network Forensic Evidence Generation and Verification Scheme (NFEGVS) to rectify the current limitation of Network Forensic technologies. This scheme can prove who and when the crime has occurred. In addition, this prevents leaking of symmetric key for guaranteeing certification and integrity of Forensic Evidence by proposing the Timestamp Secret Key Distribution Scheme, and minimizes performance degradation of router when generating forensic evidence with the Flow-Based Selection Scheme. In this paper, we implement the proposed scheme and evaluate overall performance of the proposed system.

• Journal of the Regional Association of Architectural Institute of Korea
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• v.21 no.5
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• pp.141-152
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• 2019

A gradual increase in the number of people with disabilities and the elderly in our everyday life has changed our perceptions toward them. The concept of barrier free space has been gradually incorporated into the social system and into our everyday life, and has further developed into the universal design concept so that creating an environment where all inhabitants of a city are able to enjoy the space of everyday life. Against this backdrop, this study has conducted research on how to improve the accessibility of major public spaces in Wonju, Chuncheon, and Gangneung, or major metropolitan cities of Gangwon Province. The research has been conducted under the assumption that the conditions of utilizing public spaces in those cities will not meet public expectations compared to private spaced despite being iconic cities of Gangwon Province. The field survey results show that the concept of barrier free space is reflected, to some extent, in planning and development although its role in terms of using such space is not up to expectations. In particular, the buildings and facilities built prior to the enforcement of relevant policies are found to leave much to be desired due to unsatisfactory development plans between architecture and urban public space, which necessitates improvement on relevant policies, sincere efforts of local governments, and practical guidelines that can be useful in the implementation stage. Above all, building owners and public administrations are advised to raise their awareness on the concept of universal design so that it is firmly rooted in our everyday life as one of the universal values. It should lead to the efforts of the members of local cities in providing the environment where people are able to enjoy these utilities from the perspective of promoting public welfare.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.5
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• pp.576-583
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• 2020

This paper proposes a technique to determine the spam comments on YouTube, which have recently seen tremendous growth. On YouTube, the spammers appeared to promote their channels or videos in popular videos or leave comments unrelated to the video, as it is possible to monetize through advertising. YouTube is running and operating its own spam blocking system, but still has failed to block them properly and efficiently. Therefore, we examined related studies on YouTube spam comment screening and conducted classification experiments with six different machine learning techniques (Decision tree, Logistic regression, Bernoulli Naive Bayes, Random Forest, Support vector machine with linear kernel, Support vector machine with Gaussian kernel) and ensemble model combining these techniques in the comment data from popular music videos - Psy, Katy Perry, LMFAO, Eminem and Shakira.

• Journal of Convergence for Information Technology
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• v.11 no.3
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• pp.77-86
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• 2021

This study aims to systematically review literature on organizational socialization in the field of nursing. The keywords of 'organizational socialization' and 'nursing' were combined with the AND operator, and the author analyzed the total of 26 journal articles published between 2010 and 2020. The number of journal articles on organizational socialization has increased since 2016, and all the articles took an descriptive study approach. It was found that the variables of resilience, role stress, perception of justice, bullying, professional self-concept, and organizational climate could affect organizational socialization, and the variables of intention to leave, intention on retention, resilience, and organizational commitment could be affected by organizational socialization. The result of this study can be used for guiding organizational socialization research in nursing.

• The Journal of the Convergence on Culture Technology
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• v.8 no.1
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• pp.395-402
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• 2022

The film House of Hummingbird intersects Korean modern history and personal history through the eyes of a teenage girl, and closely explores how patriarchy and Korean capitalism leave traces and internal impressions on the growing up of the female subject. This film is a meaningful text in terms of showing what changes can occur when the subject is transformed from a boy to a girl in the narrative of growth and when a feminist point of view is entered. House of Hummingbird reveals the weakness of the patriarchal symbolic order through the gaze of a teenage girl in the episodic narrative composition, and also discovers the possibility of close relationships and bonds between women in the gaps. In particular, Yeong-ji, the main character girl Eun-hee's Chinese language school lecturer, is a new female character that has never been seen in Korean teenage films. As a result, in House of Hummingbird, we meet a new female subject who negotiates the pain of growth in a 'good enough' condition.