• Journal of information and communication convergence engineering
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• v.8 no.1
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• pp.122-128
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• 2010

Efficient energy management is a very important issue in wireless sensor network since wireless sensor nodes are usually battery-powered. Recently, S-MAC protocol based on low duty-cycle has been proposed to reduce energy consumption. Even though research effort has been made to evaluate performance of S-MAC by conducting various simulations, however, some important simulation parameters are not well evaluated yet. In this paper, we identify the performance of S-MAC under different amount of streams and different patterns such as data rate and traffic. Through analyzing the simulation results, we discover weakness of S-MAC as well as analyze impact of amount of streams and packet pattern.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.2219-2236
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• 2017

With cloud storage services, users can handle an enormous amount of data in an efficient manner. However, due to the widespread popularization of cloud storage, users have raised concerns about the integrity of outsourced data, since they no longer possess the data locally. To address these concerns, many auditing schemes have been proposed that allow users to check the integrity of their outsourced data without retrieving it in full. Yuan and Yu proposed a public auditing scheme with a deduplication property where the cloud server does not store the duplicated data between users. In this paper, we analyze the weakness of the Yuan and Yu's scheme as well as present modifications which could improve the security of the scheme. We also define two types of adversaries and prove that our proposed scheme is secure against these adversaries under formal security models.

• Journal of the Korea Society of Computer and Information
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• v.21 no.7
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• pp.9-16
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• 2016

Collaborative filtering(CF) uses the purchase or item rating history of other users, but does not need additional properties or attributes of users and items. Hence CF is known th be the most successful recommendation technology. But conventional CF approach has some significant weakness, such as the new user problem. In this paper, we propose a approach using word embedding with skip-gram for learning distributed item representations. In particular, we show that this approach can be used to capture precise item for solving the "new user problem." The proposed approach has been tested on the Movielens databases. We compare the performance of the user based CF, item based CF and our approach by observing the change of recommendation results according to the different number of item rating information. The experimental results shows the improvement in our approach in measuring the precision applied to new user problem situations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.2
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• pp.881-896
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• 2016

Certificate-based cryptography is a useful public key cryptographic primitive that combines the merits of traditional public key cryptography and identity-based cryptography. It not only solves the key escrow problem inherent in identity-based cryptography, but also simplifies the cumbersome certificate management problem in traditional public key cryptography. In this paper, by giving a concrete attack, we first show that the certificate-based encryption scheme without bilinear pairings proposed by Yao et al. does not achieve either the chosen-ciphertext security or the weaker chosen-plaintext security. To overcome the security weakness in Yao et al.'s scheme, we propose an enhanced certificate-based encryption scheme that does not use the bilinear pairings. In the random oracle model, we formally prove it to be chosen-ciphertext secure under the computational Diffie-Hellman assumption. The experimental results show that the proposed scheme enjoys obvious advantage in the computation efficiency compared with the previous certificate-based encryption schemes. Without costly pairing operations, it is suitable to be employed on the computation-limited or power-constrained devices.

• Proceedings of the Korean Society of Computer Information Conference
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• 2018.07a
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• pp.461-462
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• 2018

본 논문에서는 JavaCC를 사용하여 보안약점을 찾아내는 도구를 구현한다. 이 도구는 구문 정보와 흐름 정보를 이용하여 프로그램 소스 코드에서 보안약점을 찾아 진단한다. 이를 통해 컴파일러 단계별 얻을 수 있는 정보와 관련 보안약점을 연계함으로써 보안약점에 대한 진단 방법과 분석 정보의 연계를 기대할 수 있다.

• The Journal of Engineering Research
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• v.7 no.1
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• pp.37-51
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• 2005

An and hoc network is a collection of wireless mobile nodes forming a temporary network without the centralized administration. Due to the limited transmission range of wireless work interface, multiple networks "hops" maybe needed for one node to exchange data with adjacent node. In recent years, a variety of new routing protocol about ad hoc network was developed. This paper presents a new routing protocol based on the Dynamic Source Routing which is not suitable for the high mobility ad hoc network. The Enhanced DR adapts quickly to routing changes when node movement is frequent. When a trunk route is broken, this protocol will utilize the alternative route saved in the route to discovery quickly the new route. It improves the performance of the existing DSR algorithm, so that the negative impacts from weakness of DSR are reduced.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.132-141
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• 2015

There might have been weakness in securing user authentication or verification with real time service approach, while existing unimodal biometric authentication has been used mainly for user identification and recognition. Accordingly, it is essential to research and develop ways that upgrade security performance with multi biometric based real time authentication and verification technology. This paper focused to suggest binding assignment and strategy for developing multi biometric authentication technology through investigation of advanced study and patents. Description includes introduction, technology outline, technology trend, patent analysis, and conclusion.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.210-212
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• 2011

Human Computer Interaction is rapidly growing in different aspects and areas. One of the areas that grab many scholars and researchers interest is usability. Usability is a main factor and critical pillar of products success and acceptance. In this paper, we deeply analyze the current usability models that measure the user performance during the interaction with products. Then, we fairly compare between each model to discover and present the strength and weakness of each model for supporting developer and business organization with guidelines during the development process of the products before launching the actual and final one. Decomposing comparison between each model is performed based on specific criteria. Comparison is tabulated, graphically depicted, and analytically decomposed.

• Management & Information Systems Review
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• v.34 no.5
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• pp.277-293
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• 2015

Mutual Savings Banks generally have weaker governance structure than other financial institutions, so the possibility of earnings management by owner-largest or managements of mutual savings banks is higher than other financial institutions. This study examines the relationship between corporate governance and quality of internal control of financial reporting. If the expropriation of minority shareholder hypothesis holds, we predict that the larger block shareholder in mutual savings banks, the weaker the internal control system by more likely the opportunistic earnings management by bank managers. On the other hand, under the convergence of interest hypothesis, we predict that the larger block shareholder in mutual savings banks, the stronger the internal control system by reduction in agency costs as owner-manager's holdings increases, and there a negative relationship is expected between internal control weakness and the holdings of the owner-largest shareholder. We find that mutual savings banks with higher owner-largest shareholder equity has significant positive relations with their internal control of financial reporting material weakness. This result suggests that the greater owner-largest shareholder equity, the more likely the opportunistic earnings management, so that decrease quality of internal control. This paper extends the literature on financial institutions corporate governance to verify whether governance system, especially, owner-largest and quality of internal control has significant positive relations.

• Journal of KIISE:Information Networking
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• v.30 no.6
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• pp.729-742
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• 2003

Mobile Communication has a possibility of eavesdropping by nature of wireless channel. It is known that eavesdropping of CDMA system is impossible because the voice data spreads with the PN. First of all, we show that it is possible to eavesdrop the CDMA channel by analysis of the forward channel in case that we know the ESN and the MIN. We can monitor the forward traffic channel with easy since ESN and MIN are exposed during the call processing in CDMA service in Korea. In this paper, we will show security weakness and propose an enhanced mechanism for CDMA service. We consider the problem of security in the CDMA service. CDMA system has wireless channels to transmit voice or data. By this reason, CDMA communication has a possibility of being eavesdropped by someone. It is known that eavesdropping in CDMA system is impossible because the voice data spreads with the PN. However, we can eavesdrop the CDMA data in FCM protocol in case that we know the ESN and the MIN. In CDMA system, ESN and MIN are exposed to the wireless channel. In this paper, we analyze the flow of the voice and signal in the CDMA system and monitor the forward traffic channel by the FCM protocol. The FCM protocol is proposed to monitor the forward channel in CDMA system. We can show the possibility of monitoring in one-way channel of CDMA system by the FCM protocol. The test instrument based on the FCM protocol is proposed to monitor the CDMA forward channel. We will show the system architecture of the test instrument to monitor the forward channel in CDMA.