• Journal of Korea Multimedia Society
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• v.13 no.1
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• pp.1-9
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• 2010

Today's growth of the mobile communication infrastructure made mobile computing systems like cellular phones came next to or surpassed the desktop PCs in popularity due to their mobility. Although the performance of mobile devices is now being improved continuously, it is a current common sense that compute intensive large-scale applications can hardly run on any kind of mobile handset devices. To clear up this problem, we decided to exploit the mobile cluster computing system and surveyed the existing ones first. We found out, however, that most of them are not the actual implementations but a mobile cluster infrastructure proposal or idea suggestions for reliable mobile clustering. To make cell phones participated in cluster computing nodes, in this paper, we propose a redesigned JPVM cluster computing engine and a set of WIPI mobile runtime functions interfacing with it. And we also show the performance evaluation results of real parallel applications running on our Mobile-JPVM cluster computing systems. We find out by the performance evaluation that large-scale applications can sufficiently run on mobile devices such as cellular phones when using our mobile cluster computing engine.

• Journal of IKEEE
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• v.12 no.4
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• pp.185-195
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• 2008

In this paper, PIFA(Planar Inverted F Antenna) which operates in PCS(Personal Communication System) band is designed and characteristics are investigated. Designed PIFA was installed in three types of handsets, folder, bar, slide, and the performance was evaluated. Head and hand phantom were added to make the most similar environment to real condition of mobile phone use, and influences on antenna performance were analyzed. The simulation results confirm radiation patterns are greatly changed and antenna efficiency is decreased by the effect of human body. Performance variation of the mobile handset antenna was observed as changing the angle between mobile handset and head phantom from $0^{\circ}$ to $2^{\circ},\;4^{\circ}$ to confirm the variation caused by the relative position of mobile handset and head phantom. Directivity was decreased gradually as the antenna goes away from head phantom, and showed the trend of increasing efficiency. But in the case of bar type, where the position of antenna is relatively close to head phantom, that trend didn't show. It was confirmed that the shape of handset has a great effect on the performance.

• Journal of Korea Multimedia Society
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• v.11 no.10
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• pp.1436-1445
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• 2008

Currently, mobile handset embeds many communication modules including CDMA and Bluetooth, and many applications are developed based on these modules. In this paper, we study about wireless vehicle diagnosis software and user interface based on bluetooth system on mobile handset. We developed Bluetooth communication system on protocol converter between OBD(On Board Diagnostics)-II system. Based on this system, we can communicate ECU(Engine Control Unit) and mobile device based on windows .NET compact framework platform. Therefore we can easily diagnose vehicle state and obtain engine data. All user interface and vehicle diagnosis systems on mobile handset are developed under windows .NET compact framework platform. Using this system we achieved several improvements over existing vehicle diagnostic system; 1) the software download and upgrade can be achieve on wireless environment, 2) no additional diagnostic devices are requires, which saves additional cost and we can diagnose the vehicle easily, 3) we can easily port our system on many embedded systems including PDA and navigator, etc.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.18 no.2
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• pp.21-31
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• 2008

Ubiquitous environment is constructed by development of an IT technology, offer environment of many service changed to mobile environment. Also, existed service offered at fixed position like home or company, but according to development of mobile device. user require service as moving. Wibro can offer as user moving using mobile device. As requirement should be included authentication, in case of authentication between UICC and AAA authentication server is offered in Wibro, service is available. However, when UICC requires initial authentication to AAA authentication server, identification information of UICC expose as plaintext, so privacy infringement of mobile device occurs. Therefore, identification information of terminal generate randomly using OTP(One-Time Password) that generated in mobile terminal, and we proposed mechanism of privacy protection. Also, we proposed mechanism that offer secure service to user as offer authentication from OTP framework, and offer OTP combination authentication detailedly.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.2
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• pp.232-236
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• 2010

Nowadays, mobile users have a huge amount of multimedia contents and can use these contents anytime, anywhere by advance in computer and network techniques. However, users spend too much time for searching and managing these contents in web and local file system. Expecially, small and uncomfortable user interfaces of mobile devices make it difficult to search and manage multimedia contents. Therefore, an intelligent multimedia contents management technique is needed to use these contents more efficiently. In this paper, we propose a Personalized Mobile Multimedia Contents Provider (PMMCP) System which provides personalized multimedia contents based on users' psychological patterns and situations.

• Journal of Korea Multimedia Society
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• v.12 no.8
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• pp.1089-1098
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• 2009

Recently, many researches of making more comfortable input device based on gaze detection technology have been performed in human computer interface. Previous researches were performed on the computer environment with a large sized monitor. With recent increase of using mobile device, the necessities of interfacing by gaze detection on mobile environment were also increased. In this paper, we research about the gaze detection method by using UMPC (Ultra-Mobile PC) and an embedded camera of UMPC based on face and facial feature detection by AAM (Active Appearance Model). This paper has following three originalities. First, different from previous research, we propose a method for tracking user's gaze position in mobile device which has a small sized screen. Second, in order to detect facial feature points, we use AAM. Third, gaze detection accuracy is not degraded according to Z distance based on the normalization of input features by using the features which are obtained in an initial user calibration stage. Experimental results showed that gaze detection error was 1.77 degrees and it was reduced by mouse dragging based on the additional facial movement.

• The KIPS Transactions:PartC
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• v.16C no.4
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• pp.527-534
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• 2009

Almost every mobile phone supports MMS to send and receive multimedia messages among users. MMS is suitable for different types of mobile phones and effectively operates in wireless environments. So the mobile content delivery method using MMS can be efficient. However, there would be some problems if a mobile service provider tries to deliver mobile content to subscribers by using the existing MMS. In this paper, we propose an improved data transmission and control scheme for MMS. Our scheme assists mobile service providers to deliver mobile contents easily by modifying the MMS system software. By using our scheme, mobile service providers are able to manage mobile contents stored in mobile devices. Therefore, they can provide various services such as mobile daily news service, automatic software upgrade service, mobile advertising service, etc. We verify the possibility of the proposed scheme through simulation.

• Convergence Security Journal
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• v.7 no.3
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• pp.87-93
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• 2007

We propose a mobile point-of-sale system, which consists of only mobile information terminals and personal computers. The proposed system provides most of functionalities related with resource planning, adminstration and management, provided by medium-scale or large-scale POS systems, with additional functionalities, such as automatic information gathering and management through mobile interconnection, while eliminating the necessity of additional special-purpose devices, such as bar-code systems. The proposed system transmits order information through wireless and wired communication lines, thus allowing real-time sharing of order information among diverse information devices, such as mobile order receiving terminals, main server within stores, monitors and printers located in production lines. Also, the system is able to transfer such detail information produced within stores in real-time to the enterprise-level accounting, sales, logistics, personnel management system, which facilitate enterprise-wide management and administrative decision-making. No additional programs are required for mobile terminals. Order information received by such terminals are entered into databases through web server of main server and that information is again transferred to main server and production line printers. The proposed system can handle all the point-of-sale information and can provide almost of the POS functionalities by simply utilizing wireless internet, personal computers, and mobile terminals without installing specific-purpose peripheral devices. The proposed system can be widely applied to the small-scale stores and will contribute in reducing construction and maintenance cost required for point-of-sale management.

• Journal of Industrial Technology
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• v.29 no.B
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• pp.33-39
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• 2009

The need for end-to-end security has been increased with the widespread use of mobile devices in wireless internet access applications such as mobile commerce. The WAP1.x has an end-to-end security problem that the message transmitted between the mobile device and the Web server is decrypted inside the gateway within a short time. To overcome this problem, several protocols including WAP2.0 has been proposed. These protocols require that the heavy modules such as TLS or data compression modules should be installed on the mobile device with limited resources. This paper proposes a new WTLSW(WTLS-TLS at Web server) protocol and a new WAP2.0 proxy model in order to ensure end-to-end security between the mobile device and the Web server and to be appropriate for mobile devices with limited resources.

• Journal of Digital Convergence
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• v.12 no.7
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• pp.11-20
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• 2014

This paper finds that the ultimate source of problems facing Korean mobile telecommunications such as excessive subsidies of handsets, waste of resources, and a vicious circle of expensive handsets and high prices for services, is bundling of handset and subscription. The analysis suggests that bundling causes consumers to confuse about prices of handsets and services, and firms focus on handset subsidy competition rather than on upgrading service qualities and lowering prices due to anti-competitive effects of bundling. Because most of the cost of bundling is passed on to consumers, the welfare of consumers decline. In particular, equality among consumers worsens due to price discriminations. To resolve these problems, unbundling of handset and subscription is a necessity. Mixed bundling allowing separate selling of handsets under bundling does not seem to work as a cure because bundling tends to be a dominant strategy. The best regulatory policy is a complete separation of handset and subscription.