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Pohang, South Korea

Jeung E.T.,Changwon National University | Lee K.R.,Pyeongtaek University
International Journal of Control, Automation and Systems | Year: 2014

This paper presents a design method of static output feedback control for continuous-time T-S fuzzy systems. Based on parallel distributed compensation (PDC), a static output feedback control is utilized. A new sufficient condition for the existence of static output feedback gains is represented in terms of linear matrix inequalities (LMIs). The sufficient condition does not need any transformation matrices, equality constraints, and block diagonal assumption of positive definite matrices in order to convert a bilinear matrix inequality (BMI) problem to an LMI one. © 2014 Institute of Control, Robotics and Systems and The Korean Institute of Electrical Engineers and Springer-Verlag Berlin Heidelberg.

Nam J.,Konkuk University | Choo K.-K.R.,University of South Australia | Paik J.,Pyeongtaek University
International Journal of Security and its Applications | Year: 2016

In this work, we extend the widely accepted security model of Bellare, Pointcheval and Rogaway (2000) in order to prove the security of smart-card-based roaming authentication (SRA) schemes. More specifically, in this extended model, we provide formal definitions of authenticated key exchange and user anonymity for SRA schemes, in order to capture side-channel, offline dictionary, and other common attacks. We then present a new SRA scheme and prove its security in our extended model. To the best of our knowledge, our proposed scheme is the first provably-secure SRA scheme that achieves user anonymity. We conclude by demonstrating that our scheme is also computationally efficient relative to other similar published schemes without a security proof. © 2016 SERSC.

Jang H.M.,Gwangju Institute of Science and Technology | Ha J.H.,Pyeongtaek University | Kim M.-S.,Korea Institute of Energy Research | Kim J.-O.,Hanyang University | And 2 more authors.
Water Research | Year: 2016

In recent years, anaerobic co-digestion (AcoD) has been widely used to improve reactor performance, especially methane production. In this study, we applied two different operating temperatures (thermophilic and mesophilic) and gradually increased the load of food wastewater (FWW) to investigate the bacterial communities during the AcoD of waste activated sludge (WAS) and FWW. As the load of FWW was increased, methane production rate (MPR; L CH4/L d) and methane content (%) in both Thermophilic AcoD (TAcoD) and Mesophilic AcoD (MAcoD) increased significantly; the highest MPR and methane content in TAcoD (1.423 L CH4/L d and 68.24%) and MAcoD (1.233 L CH4/L d and 65.21%) were observed when the FWW mixing ratio was 75%. However, MPR and methane yield in both reactors decreased markedly and methane production in TAcoD ceased completely when only FWW was fed into the reactor, resulting from acidification of the reactor caused by accumulation of organic acids. Pyrosequencing analysis revealed a decrease in bacterial diversity in TAcoD and a markedly different composition of bacterial communities between TAcoD and MAcoD with an increase in FWW load. For example, Bacterial members belonging to two genera Petrotoga (assigned to phylum Thermotogae) and Petrimonas (assigned to phylum Bacteroidetes) became dominant in TAcoD and MAcoD with an increase in FWW load, respectively. In addition, quantitative real-time PCR (qPCR) results showed higher bacterial and archaeal populations (expressed as 16S rRNA gene concentration) in TAcoD than MAcoD with an increase in FWW load and showed maximum population when the FWW mixing ratio was 75% in both reactors. Collectively, this study demonstrated the dynamics of key bacterial communities in TAcoD and MAcoD, which were highly affected by the load of FWW. © 2016.

Byun J.W.,Pyeongtaek University
Security and Communication Networks | Year: 2015

In this paper, we suggest a new privacy preserving smartcard-based password authenticated key exchange (SC-PAKE) with provable security. Only the user who has two secrets (smartcard and password) can go through authentication with key exchange while concealing its identifier from outsider adversaries. For guaranteeing both authentication and identity (ID) protection, we define a security of session key and an anonymity of identifier. We also show that the proposed protocol satisfies two definitions under computational Diffie-Hellman assumption and chosen ciphertext attack (CCA) secure symmetric encryption. One problem is how a common secure key (an encryption/decryption key) can be shared between a server and a user without letting the corresponding server know a certain ID of user. For this issue, we set two kinds of long-term secrets; one is used to make a symmetric key for ID protection with user's ephemeral value, and the other is issued for helping agreement of a final session key for mutual authentication. Performance analysis shows that the proposed SC-PAKE has better efficiency in computation and communication costs than recent SC-PAKE schemes. To the best of our knowledge, it is the first scheme to guarantee both the session key security with authentication and privacy-enjoying provable security. © 2015 John Wiley & Sons, Ltd.

Choi C.-S.,Correongju Correction Institution | Seo J.-M.,Pyeongtaek University | Lee H.,Seowon University
International Journal of Security and its Applications | Year: 2015

In general, personal identification using the iris is means for identifying each individual by using the unique pattern of iris. Even twins have different iris pattern image, and each right eye and left eye has a different pattern for the same individual. Thus, the iris has the best characteristics that reflect the personal differences of the human body. In this paper, we proposed an efficient iris recognition method for large scale database. The Zernike moment is used for filtering out the candidate iris data from large scale database and the multiple SVM is applied for iris recognition. The proposed method proved to be an efficient searching method because the process did not match one-to-one feature data during the searching iris database. © 2015 SERSC.

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