• Journal of Computing Science and Engineering
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• v.4 no.1
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• pp.80-95
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• 2010

In order to truly integrate e-Learning system into regular curriculum at a university, mobile access to Learning Management Systems has to be enabled. Mobile devices have the potential to be integrated into the classroom, because they contain unique characteristics such as portability, social interactivity, context sensitivity, connectivity and individuality. Adoption of Learning Management Systems by students is still on the low rate, mostly because of poor usability of existing e-Learning systems. Our initial research has confirmed this hypothesis. Usability issue is rising to the higher level on the mobile platform, because of the mobile devices' limited screen size, input interfaces and bandwidth, and also because of the context of use. Our second hypothesis was that it is wrong to consider a mobile device as a surrogate for desktop or laptop personal computer (PC). By just adopting the existing Learning Management System on mobile devices with adaptive technologies such as Google proxy, we do not acquire the satisfactory results. Usability can prove to be even lower compared to desktop application. One possible solution to the problem could be development of rich client applications for today's mobile devices that would raise the usability to a higher level. We developed a PocketPC prototype application by using user-centered design principles, which we presented as a third alternative in usability research conducted among university students. Results gathered in such a way have confirmed that development of e-Learning system, in order to be widely accepted by students, needs to have the user(student) in the center of development process.

• Journal of Internet Computing and Services
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• v.9 no.3
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• pp.9-24
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• 2008

In this paper, we describes the design of software architecture supporting for healthcare context information service platform based on multi agent in home environment. In this platform, the DOGF supports the execute object and healthcare sensors and device's logical services grouping. JADE framework can support mobility in heterogeneous environment. The multi agents on platform order to support a healthcare context information service it will be able to divide. An agent collects an environment information from distributed devices. Another an agent follows mobile-device specific and it does a different service. And an agent where it manages like this. The mobile-proxy&agent is an interface part between DOGF and JADE, support data interchange or mobility pattern. For DOGF and JADE to provide healthcare context information service, we describes the design of multi agent software platform and multi agent classification by services. Finally we showed the system environments which is physical environments and prototype based on platfonn for healthcare context information services.

• KIISE Transactions on Computing Practices
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• v.22 no.6
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• pp.296-301
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• 2016

Object-based storage is an efficient storage solution that can handle unstructured data and shows better security and scalability than traditional block-based storage. However, in terms of power management, Object-based storage writes multiple copies in storage cluster, hence many servers consume unnecessary power in idle state. In order to resolve this problem, it is necessary to apply power management strategy by adjusting power mode of servers in idle state according to their workloads. In this paper, we proposed a new dynamic power management (DPM) method to transform power mode of storage servers dynamically according to workload information sent from proxy server. The experimental result shows that the proposed power management technic reduces total power consumption by 12% in the OpenStack based Swift object storage.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.8C
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• pp.670-679
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• 2012

The recent dissemination of cloud computing makes the amount of data storage to be increased and the cost of storing the data grow rapidly. Accordingly, data and service requests from users also increases the load on the cloud storage. There have been many works that tries to provide low-cost and high-performance schemes on distributed file systems. However, most of them have some weaknesses on performing parallel and random data accesses as well as data accesses of frequent small workloads. Recently, improving the performance of distributed file system based on caching technology is getting much attention. In this paper, we propose a CHPC(Cloud storage High-Performance Caching) framework, providing parallel caching, distributed caching, and proxy caching in distributed file systems. This study compares the proposed framework with existing cloud systems in regard to the reduction of the server's disk I/O, prevention of the server-side bottleneck, deduplication of the page caches in each client, and improvement of overall IOPS. As a results, we show some optimization possibilities on the cloud storage systems based on some evaluations and comparisons with other conventional methods.

• The KIPS Transactions:PartC
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• v.13C no.1 s.104
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• pp.27-34
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• 2006

In the near future, people will wish to access many kinds of heterogeneous networks to use their services anytime and anywhere. Owing to the heterogeneity of networks, there must be many kinds of protocols to guarantee secure services. The mobile device can depend in a middleware for accessing services in the heterogeneous networks and the middleware helps the mobile device to communicate with services without blowing concrete protocols. If a secure channel is necessary, the middleware may access a private key in the mobile device to perform a security protocol. In this paper, we focus on the security of a private key in the mobile device against malicious middlewares. To do so, we introduce two models for a user to protect his/her private key against malicious middlewares by generating authentication data(e.g., digital signatures) without keeping the private key in the mobile device.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.9
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• pp.4160-4168
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• 2011

The development of computing technology and the increase of using mobile smart devices have brought about changes in our daily life. It makes accessing the internet more easy, and also increases the convenience of our daily life and the variety of information. In this paper, a system for marking the absence using a smart-phone is developed, which is one of the means to increase the convenience of our daily life. Usually the conventional system for the same purpose uses a smart card, so that there are some drawbacks in the system such as attendance by proxy. To compensate the drawbacks, the system proposed in this paper uses a smart-phone belonging to an individual and an instant authentication key to mark the absence that is generated at the time when it is required. It makes the proposed system being more effectively used in marking the absence.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.2
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• pp.452-458
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• 2021

The value and importance of personal information are increasing due to the increasing number of fields where the Internet environment and computing environment are used, and user authentication technology is also changing. Until now, accredited certificates, which are mainly used in the financial sector, are being replaced with biometric authentication technology due to the problem of revocation. However, another problem is that biometric information cannot be modified once it is leaked. Recently, with the advent of blockchain technology, research on user authentication methods has actively progressed. In this paper, both public certificate and blockchain-based user authentication can be used without system change, and a new DID issuance and reissuance method that can replace the resident registration number is presented. The proposed system can be used without restrictions in a blockchain. However, the currently used DID requires installation of an application at the Interworking Support Center for verification. Since a DID can be authenticated without registering as a member, indiscriminate information collection can be prevented. Security, convenience, and determinism are compared with the existing system, and excellence is proven based on various attack methods, its portability, and proxy use.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.5
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• pp.394-400
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• 2013

WoT (Web of Things) was proposed to realize intelligent thing to thing communications using WEB standard technology. It is difficult to adapt security protocols suited for existing Internet communications into WoT directly because WoT includes LLN(Low-power, Lossy Network) and resource constrained sensor devices. Recently, IETF standard group propose to use DTLS protocol for supporting security services in WoT environments. However, DTLS protocol is not an efficient solution for supporting end to end security in WoT since it introduces complex handshaking procedures and high communication overheads. We, therefore, divide WoT environment into two areas- one is DTLS enabled area and the other is an area using lightweight security scheme in order to improve them. Then we propose a mutual authentication scheme and a session key distribution scheme for the second area. The proposed system utilizes a smart device as a mobile gateway and WoT proxy. In the proposed authentication scheme, we modify the ISO 9798 standard to reduce both communication overhead and computing time of cryptographic primitives. In addition, our scheme is able to defend against replay attacks, spoofing attacks, select plaintext/ciphertext attacks, and DoS attacks, etc.

• Journal of Internet Computing and Services
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• v.15 no.2
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• pp.87-94
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• 2014

Social media which includes Facebook enable users to construct relationships and networks as well as sharing of information. By enlisting Facebook users as proxy, this paper attempted to analyze the different emotional states experienced by social media users, specifically to gauge what effect their usage motivation and usage pattern had on the ambivalence level of the users. The quantitative survey result revealed that usage duration or the time of day when Facebook was accessed had no relevant impact on one's ambivalence level. However, there was a direct correlation between frequency of Facebook usage and the ambivalence level. The more the user logged onto Facebook the more suppressed his or her expression became due to fear of giving negative impressions to others and also receiving their negative feedbacks, which then subsequently added to the user's ambivalence. People's main reasons for using Facebook were identified as "chatting," "communicating," "maintaining relationships," "relationship building," "networking," and "finding information about friends," but only "maintaining relationships," "communicating," and "networking" had observable effect on ambivalence. There were no noticeable differences among genders with regards to ambivalence and usage levels, but there was a marked difference based on the user's age. For example, people in their forties showed higher levels of ambivalence than those in their twenties. This may be attributed to anxiety they face as they use Facebook primarily to expand their networks and to maintain relationships. As such, it is surmised that their fatigue level from using social media will only increase. Meanwhile, Korean Facebook user's emotional manifestation tended to skew toward relation-involved ambivalence rather than the self-defensive type. This relation-involved ambivalence might be something that can actually help prevent damage to relationships by limiting excessive emotional expressions. In other words, such ambivalence by Facebook users may be a positive element in a user's social media interaction.