Daejeon, South Korea
Daejeon, South Korea

Pai Chai University is one of South Korea's oldest modern universities. Its campus is located in Seo-gu, in Daejeon metropolitan city, on the lower slopes of Yeonja Mountain. It has a present-day student body of about 14,000. Undergraduate programs are administered by the Colleges of Humanities, Foreign Studies, Business Administration, Social science, Tourism Management, Natural science, Engineering, Performing Inter-media Arts and Fine Arts. Numerous graduate programs in these fields are provided as well. Wikipedia.

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Hur J.,University of Illinois at Urbana - Champaign | Noh D.K.,Pai Chai University
IEEE Transactions on Parallel and Distributed Systems | Year: 2011

Some of the most challenging issues in data outsourcing scenario are the enforcement of authorization policies and the support of policy updates. Ciphertext-policy attribute-based encryption is a promising cryptographic solution to these issues for enforcing access control policies defined by a data owner on outsourced data. However, the problem of applying the attribute-based encryption in an outsourced architecture introduces several challenges with regard to the attribute and user revocation. In this paper, we propose an access control mechanism using ciphertext-policy attribute-based encryption to enforce access control policies with efficient attribute and user revocation capability. The fine-grained access control can be achieved by dual encryption mechanism which takes advantage of the attribute-based encryption and selective group key distribution in each attribute group. We demonstrate how to apply the proposed mechanism to securely manage the outsourced data. The analysis results indicate that the proposed scheme is efficient and secure in the data outsourcing systems. © 2011 IEEE.

Kim H.K.,Samsung | Im K.H.,Pai Chai University | Park S.C.,Kyung Hee University
Expert Systems with Applications | Year: 2010

Recently, as hacking attempts increase dramatically; most enterprises are forced to employ some safeguards for hacking proof. For example, firewall or IPS (Intrusion Prevention System) selectively accepts the incoming packets, and IDS (Intrusion Detection System) detects the attack attempts from network. The latest version of firewall works in cooperation with IDS to immediately response to hacking attempts. However, it may make false alarms that misjudge normal traffic as hacking traffic and cause network problems to block the normal IP address by false alarms. By these false alarms made by IDS, system administrators or CSOs make wrong decisions and important data may be exposed or the availability of network or server system may be exhausted. Therefore, it is important to minimize the false alarms. As a way of minimizing false alarms and supporting adequate decisions, we suggest the RFM (Recency, Frequency, Monetary) analysis methodology, which analyzes log files with incorporating three criteria of recency, frequency and monetary with statistical process control chart, and thus leads to an intuitive detection of anomaly and misuse events. Moreover, to cope with hacking attempts proactively, we apply CBR (case based reasoning) to find out similarities between already known hacking patterns and new hacking patterns. With the RFM analysis methodology and CBR, we develop DSS which can minimize false alarms and decrease the time to respond to hacking events. In case that RFM analysis module finds out unknown viruses or worms occurred, this CBR system matches the most similar incident case from case-based database. System administrators can easily get information about how to fix and how we fixed in similar cases. And CSOs can build a blacklist of frequently detected IP addresses and users. This blacklist can be used for incident handling. Finally, we propose collaborative incident response system with DSS, this distributed agent systems interactively exchange the suspicious users and source IP addresses data and decide who is true-anomalous users and which IP addresses is the most riskiest and then deny all connections from that users and IP addresses automatically with less false-positives. © 2009 Elsevier Ltd. All rights reserved.

Lee G.-H.,Dong - Eui University | Song J.-H.,Pai Chai University
Applied Surface Science | Year: 2010

Brush-shaped ZnO particles were synthesized by controlling the growth time in the direct melt oxidation process of Al-Zn mixture in air at atmospheric pressure. Particles with two kinds of structures were formed. One was consisted of nanowires grown along [0 0 0 1] direction at the six corners and the center of (0 0 0 1) basal plane on hexagonal ZnO microrod. The other was constructed by nanobelts between the corner-nanowires as well as nanowires at the corners on ZnO microrod. The structural configuration that the nanowires and the nanobelts have a well coherent orientation alignment with the base microrod implies that the brush-shaped ZnO is single crystal. Room temperature PL spectrum of the brush-shaped ZnO particles displayed predominant green emission with a wavelength of 510 nm. © 2009 Elsevier B.V. All rights reserved.

Lee S.-C.,Korea Christian University | Im K.H.,Pai Chai University
Journal of Computer Virology and Hacking Techniques | Year: 2015

The purpose of this paper is to study the differences of factors affecting banking behavior in multi-channel environment. This paper adopted multi-group structural equation modeling to compare the differences of causalities between internet and mobile banking. The result of causality in this paper generally supports the theory of technology acceptance model and the paths across the two groups are different. Certain relations in multi-channel are the same, for example the behavioral intention of internet banking and mobile banking usage are determined by perceived usefulness, trust and perceived ease of use sequentially. Alternatively, several differences exist in the external variables of beliefs. Internet banking regards self-efficiency and perceived ease of use more important. Mobile banking considers situational normality and trust more important. © 2015, Springer-Verlag France.

Kim J.,Pai Chai University
Proceedings of the 13th Docomomo International Conference Seoul: Expansion and Conflict, Seoul 2014 | Year: 2014

In the 19th and 20th centuries the Korean peninsula was in the center of "expansion and conflict" created by historical circumstances such as the opening of its ports, liberation and the Korean War. The modern architecture of Korea represents a dramatic realization of these historical circumstances. Port openings gave way to a confluence of eastern and western styles which were widely expressed in the architecture of the time. Despite the fact that architecture during the Japanese colonial era was regulated within the framework of Japanese conventions, a number of Korean architects, like Kilyong Park and Dongjin Park, produced unique work. After the liberation a movement arose which merged architecture styles within the context of Korea and its customs. However, being influenced by the US during the Korean War in 1950, this movement faced circumstances in which it had to re-new everything. In addition, the modern historical events of April 19 and May 16 had a great impact on Korean architects and on daily life. Since the opening of ports, throughout the Korean War and even in modern times a consistently applicable key word during this country's conversion has been "nationality", a word which each generation has interpreted differently within a broad spectrum of meaning.

Hong J.-H.,Pai Chai University
Molecules | Year: 2013

1-Trimethylsilyl, 1-R (R = Me, Et, i-Bu)-2,3,4,5-tetraphenyl-1- silacyclopentadiene [Ph4C4Si(SiMe3)R] are synthesized from the reaction of 1-trimethylsilyl,1-lithio-2,3,4,5-tetraphenyl- 1-silacyclopentadienide anion [Ph4C4SiMe3] -•[Li]+ (3) with methyl iodide, ethyl iodide, and i-butyl bromide. The versatile intermediate 3 is prepared by hemisilylation of the silole dianion [Ph4C4Si]-2•2[Li] + (2) with trimethylsilyl chloride and characterized by 1H-,13C-, and 29Si-NMR spectroscopy. 1,1-bis(R)-2,3,4,5-tetraphenyl-1-silacyclopentadiene [Ph4C 4SiR2] {R = n-Bu (7); t-Bu (8)} are synthesized from the reaction of 2 with n-butyl bromide and t-butyl bromide. Reduction of 7 and 8 with lithium under sonication gives the respective 3-silolenide 2,5-carbodianions {[Ph4C4Si(n-Bu)2] -2•2[Li]+ (10) and [Ph4C 4Si(t-Bu)2]-2•2[Li]+ (11)}, which are characterized by 1H-, 13C-, and 29Si-NMR spectroscopy. Polarization of phenyl groups in 3 is compared with those of silole anion/dianion, germole anion/dianion, and 3-silolenide 2,5-carbodianions 10 and 11. © 2013 by the authors.

The previously unknown silole dianion [SiC 4Et 4] 2-•2[Li] + (3) was prepared by the sonication of 1,1-dichloro-2,3,4,5-tetraethyl-1-silacyclopentadiene [Cl 2SiC 4Et 4, 2] with more than four equivalent of lithium in THF. 1H-, 13C-, and 29Si-NMR data of 3 are compared with those of the reported silole dianion [SiC 4Ph 4] 2-. Trapping of 3 with trimethylchlorosilane gave 1,1-bis(trimethylsilyl)-2,3,4,5-tetraethyl-1-silacyclopentadiene [(Me 3Si) 2SiC 4Et 4, 4] in high yield. The silole of 2 was synthesized in high yield in three steps by a modified procedure using Cp 2ZrCl 2 via Cp 2ZrC 4Et 4 and 1,4-dibromo-1,2,3,4-tetraethyl-1,3-butadiene. © 2011 by The Authors.

Sung S.H.,Pai Chai University
Computers and Mathematics with Applications | Year: 2011

For a positive function φ defined on (0,∞), an integral representation is obtained for each of the three series ∑n= 1∞P(|X|>φ(n)),∑n=1∞φ( n)-1E|X|I(|X|>φ(n)), and ∑n= 1∞ φ2( n)-1E X2I(|X|≤φ(n)). Equivalence conditions for convergence of each of the series are also obtained. Using these results, we can give sufficient conditions for the strong law of large numbers for weighted sums of random variables. © 2011 Elsevier Ltd. All rights reserved.

Kim J.,Pai Chai University | Craig D.A.,Sangmyung University
Computer Assisted Language Learning | Year: 2012

Videoconferencing offers new opportunities for language testers to assess speaking ability in low-stakes diagnostic tests. To be considered a trusted testing tool in language testing, a test should be examined employing appropriate validation processes (Chapelle, C.A., Jamieson, J., & Hegelheimer, V. (2003). Validation of a web-based ESL test. Language Testing, 20, 409-439.). While developing a speaking test, language testers need to gather evidence to build a validity argument with theoretical rationales. These rationales should be based on test purpose and validation considerations that affect decision making on test design and validation (Chapelle, C. (2001). Computer applications in second language acquisition: Foundations for teaching, testing, and research. Cambridge: Cambridge University Press.). To obtain theoretical soundness in validation, spec-driven test development (Davidson, F., & Lynch, B. (2002). Testcraft: A teacher's guide to writing and using language test specifications. New Haven, CT and London: Yale University Press.) was applied to speaking test development. Experimental tests were carried out with 40 test takers using face-to-face and videoconferenced oral interviews. Findings indicated no significant difference in performance between test modes, neither overall nor across analytic scoring features. Findings from qualitative data also evidenced the comparability of the videoconferenced and face-to-face interviews in terms of comfort, computer familiarity, environment, non-verbal linguistic cues, interests, speaking opportunity, and topic/situation effects with little interviewer effect. Data taken from test spec evolution, test scores, post interview, and observations were analyzed to build a validity argument using Bachman and Palmer's (1996. Language testing in practice. Oxford: Oxford University Press.) usefulness analysis table. The collected evidence suggests that the videoconferenced interview was comparable to the face-to-face interview with respect to reliability, construct validity, authenticity, interactiveness, impact, and practicality. © 2012 Copyright Taylor and Francis Group, LLC.

The reductive cleavage of the Si-Si bond in 1,1-bis(1-methyl-2,3,4,5- tetraphenyl-1-silacyclopentadiene) [(C 4Ph 4SiMe) 2] (1) with either Li or Na in THF gives the silole anion [MeSiC 4Ph 4] - (2). The head-to-tail dimerization of the silole anion 2 gives crystals of the disilatricyclic diallylic dianion [(C 4Ph 4SiMe) 2] -2 (3). The derivatization of 3 (crystals) with bromoethane (gas) under reduced pressure provides [(MeSiC 4Ph 4Et) 2] (4) quantitatively. The reverse addition of 3 in THF to trimethylsilyl chloride, hydrogen chloride, and bromoethane in THF gives 1-methyl-1-trimethylsilyl-1-silole [Me 3SiMeSiC 4Ph 4] (6), 1-methyl-2,3,4,5- tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1-silole [C 4Ph 4H 2SiMe-MeSiC 4Ph 4] (7), and 1-methyl-2,5-diethyl-2,3,4,5-tetraphenyl-1-silacyclo-3-pentenyl-1-methyl-1- silole [C 4Ph 4Et 2SiMe-MeSiC 4Ph 4] (8), respectively. The reaction products unambiguously suggest that the silole anion [MeSiC 4Ph 4] - is generated by coordination of the chloride ion at the silicon atom in 3 or by the nucleophilic substitution of either chloride or bromide ion at one of two silicon atoms in 3. The quenching reaction of 3 dissolved in THF with water gives 1,2,3,4-tetraphenyl-2-butene, the disiloxane of 1-methyl-2,3,4,5- tetraphenyl-1-silacyclo-3-pentenyl [O(MeSiC 4Ph 4) 2] (10) and methyl silicate.

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