• Journal of information and communication convergence engineering
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• 제9권6호
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• pp.676-682
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• 2011

Sybil attack can disrupt proper operations of wireless sensor network by forging its sensor node to multiple identities. To protect the sensor network from such an attack, a number of countermeasure methods based on RSSI (Received Signal Strength Indicator) and LQI (Link Quality Indicator) have been proposed. However, previous works on the Sybil attack detection do not consider the fact that Sybil nodes can change their RSSI and LQI strength for their malicious purposes. In this paper, we present a Sybil attack detection method based on a transmission power range. Our proposed method initially measures range of RSSI and LQI from sensor nodes, and then set the minimum, maximum and average RSSI and LQI strength value. After initialization, monitoring nodes request that each sensor node transmits data with different transmission power strengths. If the value measured by monitoring node is out of the range in transmission power strengths, the node is considered as a malicious node.

• 한국멀티미디어학회논문지
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• 제18권12호
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• pp.1483-1491
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• 2015

Applications of Internet of Things (IoT) supply various conveniences, however unsolved security problems such as personal privacy, data manipulation cause harm to persons, even nations and an limit the applicable areas of Internet of IoT technology. Therefore, study about secure and efficient security system on IoT are required. This paper proposes ID-based remote user authentication scheme in IoT environments. Proposed scheme provides untraceability of users by using different pseudonym identities in every session and reduces the number of variables. Our proposal is secure against inside attack, smart card loss attack, user impersonation attack, server masquerading attack, online/offline password guessing attack, and so on. Therefore, this can be applied to the lightweight IoT environments.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권4호
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• pp.822-839
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• 2011

Group key agreement protocols derive a shared secret key for a group of users to ensure data confidentiality or/and integrity among the users in the subsequent communications. In this paper, we inspect two group key agreement schemes which have been proposed by Shi et al. and Zheng et al. in 2005 and 2007 respectively. Although both schemes were claimed to be secure in a heuristic way, we reveal several flaws using the Bellare-Rogaway security model extended to multi-party setting by Bresson et al. These flaws are found to be originated from inappropriate selection of key derivation function, inadvertent exclusion of partners' identities from the protocol specification and insufficient consideration in preserving known temporary information security and key freshness properties. Furthermore, we suggest and discuss proper countermeasures to address such flaws.

• 호남수학학술지
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• 제39권2호
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• pp.217-231
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• 2017

In this paper, we introduce a generating function for a Legendre-based poly-Bernoulli polynomials and give some identities of these polynomials related to the Stirling numbers of the second kind. By making use of the generating function method and some functional equations mentioned in the paper, we conduct a further investigation in order to obtain some implicit summation formulae for the Legendre-based poly-Bernoulli numbers and polynomials.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권3호
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• pp.1289-1310
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• 2016

Dynamic ID-based authentication solves the ID-theft problem by changing the ID in each session instead of using a fixed ID while performing authenticated key exchanges between communicating parties. User anonymity is expected to be maintained and the exchanged key kept secret even if one of the long-term keys is compromised in the future. However, in the conventional dynamic ID-based authentication scheme, if the server's long-term key is compromised, user anonymity can be broken or the identities of the users can be traced. In addition, these schemes are vulnerable to replay attacks, in which any adversary who captures the authentication message can retransmit it, and eventually cause the legitimate user to be denied service. This paper proposes a novel dynamic ID-based authentication scheme that preserves forward anonymity as well as forward secrecy and obviates replay attacks.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.628-631
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• 2009

In this paper, we proposed a new authentication method using video that was taken during moving a hand-held camera in front of the face. The proposed method extracted individuality from the obtained image sequences using the parametric eigenspace scheme. Changes of facial appearance through authentication trials draw continuous tracks in the low dimensional igenspace. The similarity between their continuous tracks are calculated by DP-matching to verify their identities. Experimental results confirmed that different motions and persons change the shapes of continuous tracks, so the proposed method could identify the person.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2021년도 춘계학술발표대회
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• pp.567-569
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• 2021

Due to the important role of avatars in computer-mediated communication (CMC), a growing number of CMC-based services now support avatar customization options. However, in many cases, customization and personalization options are limited to visual features. In this paper, we propose and describe a prototype for a vocal customization web application. Titled Voice Creator, the app is designed for both able-bodied and speech- or hearing-impaired users who seek to communicate anonymously using digital voice identities.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권9호
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• pp.2529-2549
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• 2023

For effectively lowering down the risk of cyber threating, the zero-trust architecture (ZTA) has been gradually deployed to the fields of smart city, Internet of Things, and cloud computing. The main concept of ZTA is to maintain a distrustful attitude towards all devices, identities, and communication requests, which only offering the minimum access and validity. Unfortunately, adopting the most secure and complex multifactor authentication has brought enterprise and employee a troublesome and unfriendly burden. Thus, authors aim to incorporate machine learning technology to build an employee behavior analysis ZTA. The new framework is characterized by the ability of adjusting the difficulty of identity verification through the user behavioral patterns and the risk degree of the resource. In particular, three key factors, including one-time password, face feature, and authorization code, have been applied to design the adaptive multifactor continuous authentication system. Simulations have demonstrated that the new work can eliminate the necessity of maintaining a heavy authentication and ensure an employee-friendly experience.

• Journal of Microbiology and Biotechnology
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• 제22권11호
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• pp.1532-1539
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• 2012

The ${\alpha}$-galactosidase-coding gene agaAJB13 was cloned from Sphingomonas sp. JB13 showing 16S rDNA (1,343 bp) identities of ${\leq}97.2%$ with other identified Sphingomonas strains. agaAJB13 (2,217 bp; 64.9% GC content) encodes a 738-residue polypeptide (AgaAJB13) with a calculated mass of 82.3 kDa. AgaAJB13 showed the highest identity of 61.4% with the putative glycosyl hydrolase family 36 ${\alpha}$-galactosidase from Granulicella mallensis MP5ACTX8 (EFI56085). AgaAJB13 also showed <37% identities with reported protease-resistant or Sphingomonas ${\alpha}$-galactosidases. A sequence analysis revealed different catalytic motifs between reported Sphingomonas ${\alpha}$-galactosidases (KXD and RXXXD) and AgaAJB13 (KWD and SDXXDXXXR). Recombinant AgaAJB13 (rAgaAJB13) was expressed in Escherichia coli BL21 (DE3). The purified rAgaAJB13 was characterized using p-nitrophenyl-${\alpha}$-D-galactopyranoside as the substrate and showed an apparent optimum at pH 5.0 and $60^{\circ}C$ and strong resistance to trypsin and proteinase K digestion. Compared with reported proteaseresistant ${\alpha}$-galactosidases showing thermolability at $50^{\circ}C$ or $60^{\circ}C$ and specific activities of <71 U/mg with or without protease treatments, rAgaAJB13 exhibited a better thermal stability (half-life of >60 min at $60^{\circ}C$) and higher specific activities (225.0-256.5 U/mg). These sequence and enzymatic properties suggest AgaAJB13 is the first identified and characterized Sphingomonas ${\alpha}$-galactosidase, and shows novel protease resistance with a potential value for basic research and industrial applications.

• 방송공학회논문지
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• 제12권5호
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• pp.480-490
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• 2007

정치, 경제적인 환경의 변화는 새로운 문화 개념과 문화 정책의 패러다임 변화를 동시에 요구하고 있다. 특히 디지털 기술의 진보에 따른 디지털 다채널의 환경에서, 문화산업으로서의 방송은 그 내용 뿐 아니라 그것이 창조되고 생산되는 기반의 조성이 무엇보다도 중요하다고 하겠다. 특히 최근의 한미 FTA 협정 체결에 따른 방송시장 개방은 우리나라 방송영상산업에 있어서 외국자본의 유입에 대한 평가와 함께 문화적 다원성과 문화 정체성 유지에 대한 고민을 동시에 던져주고 있다. 이러한 측면에서 본 연구는 글로벌 미디어 환경이라고 하는 새로운 매체 환경에 직면해, 프로그램의 내용에서 문화적 다양성을 확보할 수 있는 대안을 살펴보고자 한다. 세부적인 연구 내용은 문화의 혼종화를 이루어내고 있는 방송 프로그램의 국제공동제작 실태 점검과 지역적 대안 제시, 그리고 최근에 활기를 띄고 있는 프로그램 포맷 산업의 현황 파악과 가능성을 진단하는 것으로 구성되어 있다. 글로벌 다채널 환경의 도래와 더불어 세계적으로 프로그램 거래가 활성화되고 있는 현 시점에서 문화 정체성과 보편성을 함께 고려할 수 있는 국제공동제작과 포맷 산업은 각국의 문화적 장벽을 극복하고, 콘텐츠의 다원적 이용과 이윤의 다각화를 실현할 수 있는 대안으로 고려되어야 할 것이다.