• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권11호
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• pp.5642-5670
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• 2017

Antivirus is an important issue to the security of virtual machine (VM). According to where the antivirus system resides, the existing approaches can be categorized into three classes: internal approach, external approach and hybrid approach. However, for the internal approach, it is susceptible to attacks and may cause antivirus storm and rollback vulnerability problems. On the other hand, for the external approach, the antivirus systems built upon virtual machine introspection (VMI) technology cannot find and prohibit viruses promptly. Although the hybrid approach performs virus scanning out of the virtual machine, it is still vulnerable to attacks since it completely depends on the agent and hooks to deliver events in the guest operating system. To solve the aforementioned problems, based on in-memory signature scanning, we propose an agentless runtime antivirus system VirtAV, which scans each piece of binary codes to execute in guest VMs on the VMM side to detect and prevent viruses. As an external approach, VirtAV does not rely on any hooks or agents in the guest OS, and exposes no attack surface to the outside world, so it guarantees the security of itself to the greatest extent. In addition, it solves the antivirus storm problem and the rollback vulnerability problem in virtualization environment. We implemented a prototype based on Qemu/KVM hypervisor and ClamAV antivirus engine. Experimental results demonstrate that VirtAV is able to detect both user-level and kernel-level virus programs inside Windows and Linux guest, no matter whether they are packed or not. From the performance aspect, the overhead of VirtAV on guest performance is acceptable. Especially, VirtAV has little impact on the performance of common desktop applications, such as video playing, web browsing and Microsoft Office series.

• Child Studies in Asia-Pacific Contexts
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• 제6권2호
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• pp.59-72
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• 2016

We examined the relationship between the extent of Facebook usage and social well-being with consideration of cyberbullying involvement using a person-oriented approach. Survey data were collected from a sample of 312 secondary students from Grades 7 and 8 in Hong Kong. Levels of cyberbullying involvement, Facebook usage and perceived social support were investigated. Participants were classified into three clusters based on the different levels of Facebook usage and cyberbullying victimization through cluster analyses (i.e., frequent Facebook user/noncyberbullied victim, frequent Facebook user/cyberbullied victim, and uninvolved). Our results showed that frequent Facebook users who are cyberbullied tend to engage in cyberbullying perpetration significantly more than the frequent Facebook users who are not cyberbullied, even when the latter reported higher Facebook usage. This result provides some support for the idea that cyberbullying victimization has additional value on top of the level of usage in explaining one's participation in cyberbullying perpetration. As expected, frequent Facebook users who were not cyberbullied reported the highest perceived social support among the three groups. What is even more interesting is the equal level of perceived social support found between the cyberbullied victims and the uninvolved. Our results suggest that, although limiting adolescents' Internet use might reduce their risks of being involved in cyberbullying, it might also take away the potential benefits they could get from interacting with the online community. Benefits of using the person-oriented approach in the study of cyberbullying are discussed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권12호
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• pp.4508-4530
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• 2021

Today distributed data storage service are being widely used. However lack of proper means of security makes the user data vulnerable. In this work, we propose a Randomized Block Size (RBS) model for secure data storage in distributed environments. The model work with multifold block sizes encrypted with the Chinese Remainder Theorem-based RSA (C-RSA) technique for end-to-end security of multimedia data. The proposed RBS model has a key generation phase (KGP) for constructing asymmetric keys, and a rand generation phase (RGP) for applying optimal asymmetric encryption padding (OAEP) to the original message. The experimental results obtained with text and image files show that the post encryption file size is not much affected, and data is efficiently encrypted while storing at the distributed storage server (DSS). The parameters such as ciphertext size, encryption time, and throughput have been considered for performance evaluation, whereas statistical analysis like similarity measurement, correlation coefficient, histogram, and entropy analysis uses to check image pixels deviation. The number of pixels change rate (NPCR) and unified averaged changed intensity (UACI) were used to check the strength of the proposed encryption technique. The proposed model is robust with high resilience against eavesdropping, insider attack, and chosen-plaintext attack.

• 품질경영학회지
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• 제44권3호
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• pp.689-706
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• 2016

Purpose: This study identifies causality in IoT-based healthcare user's experience(playful experience, economical experience), trust, usage, degree of dependence and continuous use intention, especially focused on chinese case. Methods: Face to face interviews was conducted for people who has experience in the use of the Xiaomi Mi band. This study used Partial Least Square(PLS) method with the questionnaires from the interview. Results: IoT-based healthcare users taking playful experience have a strong trust in a positive economic experiences. Also, the user recognizing the experience as an economic one shows stronger intention to use continuously. Conclusion: By getting healthcare users have more economic experience, they have continuous use intention of healthcare product. The empirical findings can be applied to the related companies strategy building.

• 지식경영연구
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• 제20권4호
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• pp.149-168
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• 2019

In the era of the Fourth Industrial Revolution, digital transformation is emerging in the education and learning fields. As the use of the mobile Internet and mobile devices has become a daily life, mobile learning that supports a variety of learning in a mobile environment is drawing attention. Mobile learning applications (apps) are expected to expand their use by providing a convenient learning environment anytime, anywhere. This study investigates the use of mobile learning apps in English education, which is one of the most popular learning areas, and empirically examines the factors that influence the continuous use of mobile learning apps. In particular, it analyzes the differences between Chinese and Korean users. The results of this study provide theoretical and practical implications to promote the development of mobile apps suitable for mobile learning environments and the sustainable user growth in mobile learning.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권7호
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• pp.2719-2735
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• 2015

In the cloud environment, users pay more attentions to their data security since all of them are stored in the cloud server. Researchers have proposed many mutual authentication schemes for the access control of the cloud server by using the smart card to protect the sensitive data. However, few of them can resist from the smart card lost problem and provide both of the forward security and the backward security. In this paper, we propose a novel authentication scheme for cloud computing which can address these problems and also provide the anonymity for the user. The trick we use is using the password, the smart card and the public key technique to protect the processes of the user's authentication and key exchange. Under the Elliptic Curve Diffie-Hellman (ECDH) assumption, it is provably secure in the random oracle model. Compared with the existing smart card based authentication schemes in the cloud computing, the proposed scheme can provide better security degree.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권11호
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• pp.4028-4049
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• 2014

Attribute-based encryption (ABE) is a promising cryptographic primitive for implementing fine-grained data sharing in cloud computing. However, before ABE can be widely deployed in practical cloud storage systems, a challenging issue with regard to attributes and user revocation has to be addressed. To our knowledge, most of the existing ABE schemes fail to support flexible and direct revocation owing to the burdensome update of attribute secret keys and all the ciphertexts. Aiming at tackling the challenge above, we formalize the notion of ciphertext-policy ABE supporting flexible and direct revocation (FDR-CP-ABE), and present a concrete construction. The proposed scheme supports direct attribute and user revocation. To achieve this goal, we introduce an auxiliary function to determine the ciphertexts involved in revocation events, and then only update these involved ciphertexts by adopting the technique of broadcast encryption. Furthermore, our construction is proven secure in the standard model. Theoretical analysis and experimental results indicate that FDR-CP-ABE outperforms the previous revocation-related methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권12호
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• pp.5328-5346
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• 2016

An optimal power control algorithm based on convex optimization is proposed for base stations in long term evolution networks. An objective function was formulated to maximize the proportional fairness of the networks. The optimal value of the objective function was obtained using convex optimization and distributed methods based on the path loss model between the base station and users. Field tests on live networks were conducted to evaluate the performance of the proposed algorithm. The experimental results verified that, in a multi-cell multi-user scenario, the proposed algorithm increases system throughputs, proportional fairness, and energy efficiency by 9, 1.31 and 20.2 %, respectively, compared to the conventional fixed power allocation method.

• 한국정보과학회논문지:시스템및이론
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• 제33권12호
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• pp.894-906
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• 2006

모바일 기기의 성능 및 화면, 무선 네트워크의 속도 등의 제약으로 모바일 컨텐츠 개발에는 많은 어려움이 있다. 단순히 유선 웹상에서 기존에 서비스 되던 컨텐츠의 가시적인 축소만으로는 양질의 컨텐츠 제작이 어렵다. 빠르게 변화하는 모바일 컨텐츠 시장에 적응하기 위해서는 컨텐츠 특성에 최적화된 데이타 표현 기법 및 저작 도구의 개발이 이루어져야 한다. 본 논문에서는 모바일 기기 상에서의 한자 학습을 위한 적은 용량의 모바일 컨텐츠 및 저작 도구를 개발하였다. 본 연구에서 개발한 모바일 컨텐츠는 단순히 한자 이미지와 설명 정보를 보여주는 것이 아니라, 한자 획순으로 붓으로 쓰는 것과 같은 애니메이션 효과를 줄 수 있다. 또한 저작 도구는 사용자가 그래픽이나 한자, 모바일 프로그래밍에 관한 전문가가 아니더라도 쉽고 빠르게 컨텐츠를 생성할 수 있는 개발 환경을 제공한다. 본 논문은 트루타입 폰트로부터 글자 모양을 획득하여, 간단한 사용자 입력으로 획 분할 및 획 순서 정보를 얻고, 자동으로 획의 방향을 추출, 각 획마다 붓으로 쓰는 효과의 애니메이션을 생성한다. 다음으로 모바일 기기에서의 효율적인 글자 애니메이션을 위해 애니메이션 데이타를 압축한다. 본 논문은 한자뿐 아니라, 한글 또는 다른 형태의 그래픽에도 이용될 수 있으며, 향후 획 분할 및 획 순서 결정을 자동화하는 방법을 연구하고자 한다.

• 한국산업정보학회논문지
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• 제17권1호
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• pp.11-20
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• 2012

Due to the development of internet technology, the online business trade becomes an active area. Online negotiation supporting systems have been developing very actively in recent years to meet the growing needs. We have been studying on the effect that the haptic device brings about in interaction through online negotiation between two parties. In order to meet the online negotiation's requirements, the developed interface should be able to protect user's anonymity, convey user's emotion and make the scene alive.In this study, we adopt haptic interaction as a means of conveying emotion in an online negotiation between Japanese and Chinese people. In this study, our goal is to investigate the effectiveness of haptic interaction in communications between Chinese and Japanese users and analyze the characteristis in operation the haptic device. We conducted online negotiation experiments with and without haptic interaction . The comparison experiments results show that the haptic feedback can help to convey the emotion and the sense of presence. The Chinese subjects' feedback for the questionaire concerning the emotional communication and the sense of presence varies slightly compared to the Japanese subjects. We also found when using the haptic device, the force feedback can influence subject's feelings.There is little significant difference between the advanced and the medium subjects in negotiation dialogues and the haptic device's operation, the beginner subjects are slightly at a disadvantage.