• Journal of English Language & Literature
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• v.55 no.6
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• pp.1193-1220
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• 2009

This study examined the impact of sonority profiles, positional differences and L2 proficiency on Korean EFL learners' perception of English biconsonantal clusters, using nonce words. The overall results showed that major predictions of the sonority-based typological markedness on consonant clusters were supported, as obstruent plus sonorant and sonorant plus obstruent sequences were better perceived than obstruent only or sonorant only sequences. Yet, some consonant clusters did not show a preference for sonority profiles. Positional effects were also confirmed, as word-initial biconsonantal clusters were better perceived than wordfinal ones across all the participant groups. Participants' English proficiency turned out to be also important in the perception of consonant clusters, since university students' mean rate of accuracy was highest, followed by that of high school students, which in turn followed by that of middle school students. Further, the effects of other factors like frequency and stimuli on speech perception were also addressed, along with some implications for future research.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.22 no.3
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• pp.515-524
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• 2012

Fault attacks are a powerful side channel analysis extracting secret information by analyzing the result after injecting faults physically during the implementation of a cryptographic algorithm. First, this paper analyses vulnerable points of existing Digital Signature Algorithm (DSA) schemes secure against fault attacks. Then we propose a new signature algorithm immune to all fault attacks. The proposed DSA scheme is designed to signature by using two nonce and an error diffusion method.

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.2
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• pp.81-85
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• 2009

In VANET, it is required one-way broadcast transmission because vehicles move at high speed and warning messages need to broadcast. our protocol employs digital signatures to authenticate nodes along the path. this prevents impersonation attacks and message modification attacks. our protocol also employs the node list to recognize intermediate nodes of the path. The node list, the time, and the nonce can prevent replay attacks.

• The Journal of the Korea Contents Association
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• v.14 no.11
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• pp.533-540
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• 2014

As for the application system or the user authentication scheme that is used in the system, various technologies including simple ID/PW, certificate, fingerprint/iris, phone, security card, and OTP are being used. But simple ID/PW and phone certification lack security features. As for the certificate, fingerprint/iris, and security card/OTP, the weakness in security has been quite strengthened, but there are costs and complexity involved to use these. This paper proposes a new measure of much safer and low-cost user authentication that improves the security level and uses mobile external storage media such as USB that people commonly have.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.2
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• pp.94-101
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• 2009

We introduce a user authentication system using distance estimation and a simple challenge response protocol based on a pre-established key. Using the time difference of arrival between an RF signal and an ultrasonic signal, an authenticator verifies if a user's authentication token is within its threshold distance, and it also verifies if the token's response to its random challenge is valid. We implement our authentication system and we analyze the success rates for authentication according to the variations in the distances and facing angles between the authenticator and the token. Our experimental results show that the token is authenticated with very high probability in reasonable settings.

• ETRI Journal
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• v.28 no.4
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• pp.444-452
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• 2006

Biometric-based authentication can provide a strong security guarantee of the identity of users. However, the security of biometric data is particularly important as any compromise of the biometric data will be permanent. In this paper, we propose a secure and efficient protocol to transmit fingerprint images from a fingerprint sensor to a client by exploiting the characteristics of the fingerprint images. Because the fingerprint sensor is computationally limited, a standard encryption algorithm may not be applied to the full fingerprint images in real-time to guarantee the integrity and confidentiality of the fingerprint images transmitted. To reduce the computational workload on the resource-constrained sensor, we apply the encryption algorithm to a nonce for integrity and to a specific bitplane of each pixel of the fingerprint image for confidentiality. Experimental results show that the integrity and confidentiality of the fingerprint images can be guaranteed without any leakage of the fingerprint ridge information and can be completed in real-time on embedded processors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.1
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• pp.16-20
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• 2004

This paper developed a secure web-based digital notary system. The system conforms to international standards, and gives users very good accessibility to it. The technologies and the application systems for timestamp-related services are not yet popularized, but they are potentially meaningful to many kinds of areas such as ecommerces, digital right managements, and internet mail systems. The digital notary system uses the timestamp requests and responses which conforms to rfc 3161. The system supports secure communication between web-based notary server and its clients by using SSL(Secure Socket Layer), and use nonces for prevention of replay attacks.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.77-84
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• 2011

In this paper we implement a 6LoWPAN protocol on the MICAz sensor platform, which could minimize packet re-transmission, and support security primitives for packet integrity and confidentiality. And we also present a performance evaluation of the implemented protocol calculated according to the cryptographic algorithms. In the re-transmission method, time stamp, nonce, and checksum are considered to protect replay attacks. As cryptographic algorithms, AES, 3DES, SHA2, and SHA1 are implemented. If transmission errors (thus, packet losses) and the number of hops are increase then, packet re-transmissions are increase exponentially from the experimental results. Also, the result shows that cryptographic operations take more time than packet re-transmission time.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.189-199
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• 2005

Now it is increasing the necessity for micropayment system according to activation for trade on internet. Because of the reason, it is requesting safety for personal information as well as for payment cost. But current micropayment systems cannot support anonymity or have heavy overheads in payment process. This paper suggests a micropayment system to keep anonymity of users and also to keep payment cost safe. The proposed system is to use blind signature anonymous ID which is combined nonce with an encryption of personal information. It also keeps payment cost of users by reconfirmation payment cost and product from certification and increases the computational efficiency by using secret key and session key instead of public key.

• Journal of Korea Society of Industrial Information Systems
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• v.10 no.2
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• pp.59-66
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• 2005

Recently, Ku and Chen(Ku-Chen) showed some problems in the password based remote user authentication scheme using smartcards proposed by Chien et al. and proposed an improvement from it. This paper shows some weaknesses in the Ku-Chen's scheme, especially the replay attacks, and proposes two authentication protocols to solve the problems in it. First of all, an authentication protocol using synchronized timestamps is proposed to solve the problem in the Ku-Chen's protocol. Then, a nonce-based authentication protocol is proposed to solve the inherent problems in the synchronized timestamp-based authentication protocols. The proposed authentication protocols support the advantages in the previous password-based authentication protocols and solve the problems in them effectively.