• Journal of Korea Game Society
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• v.1 no.1
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• pp.94-101
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• 2001

Although the latest break-through of mobile industry has limited customers' free time to PC games, today's advancement of wireless mobile communication made this trend move to more specialized and diversified games implemented into cellular phones. Therefore, this paper intends to provide information on mobile games and strategic skills to prove its relative effects.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.456-458
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• 2005

As a viable alternative to magnetic transformers in the power supply for portable electronics, this paper presents a miniaturized off-line travel adapter or charger for cellular phones using the piezoelectric transformer. Various design considerations in the design of ac PT adapters are investigated before coming up with the proposed pseudo-resonant topology. A prototype hardware design is also presented and verified by simulations and experiments

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.414-417
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• 2008

A lid & frame used as the shield of electromagnetic waves in cellular phones are composed of frame, which is welded at their electric circuits, and lid, of which debonding and joining are available from the frame. Typical lid & frame were mechanically bonded by contact between the embossing of lid and the piercing of frame Bonding force of this part have to allow us to detach the lid from frame for exchange or fix of the electric part and have to be high enough to protect the electric part from external impacts. This study is designed to estimate the effect of design variable of lid & frame on its debonding force. Estimations were performed by finite element method.

• ETRI Journal
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• v.30 no.5
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• pp.735-737
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• 2008

We propose a novel spatial multi-band-stop filter using modified multiple loop array elements to block electromagnetic waves or signals of mobile phones in public facilities. It operates at the following frequency bands: Korean cellular (824 MHz to 894 MHz), Personal Communication Service (PCS) (1.75 GHz to 1.87 GHz), and IMT-2000 (1.92 GHz to 2.17 GHz). Two frequency selective surfaces with modified multiple-loop elements are printed on the top and bottom of a pair-glass pane, which is a pair of glass panes with an air gap between them. A modified multiple-loop element with a meander line is used to make the size of the filter compact. The simulated and measured results show good agreement, which confirms the usefulness of the proposed tri-band spatial filter.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.32B no.1
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• pp.96-102
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• 1995

This paper presents the VHSIC Hardware Description Language(VHDL) implementation of the Fixed Point Covariance Lattice(FLAT) algorithm for an Linear Predictive Coding(LPC) analysis and its related algorithms, such as the forth order high pass Infinite Impulse Response(IIR) filter, covariance matrix calculation, and Spectral Smoothing Technique(SST) in the Vector Sum Exited Linear Predictive(VSELP) speech coder that has been Selected as the standard speech coder for the North America and Japanese digital cellular. Existing Digital Signal Processor(DSP) chips used in digital cellular phones are derived from general purpose DSP chips, and thus, these DSP chips may not be optimal and effective architectures are to be designed for the above mentioned algorithms. Then we implemented the VHDL code based on the C code, Finally, we verified that VHDL results are the same as C code results for real speech data. The implemented VHDL code can be used for performing logic synthesis and for designing an LPC Application Specific Integrated Circuit(ASOC) chip and DsP chips. We first developed the C language code to investigate the correctness of algorithms and to compare C code results with VHDL code results block by block.

• 한국정보교육학회:학술대회논문집
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• 2011.01a
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• pp.133-138
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• 2011

This study investigates the usefulness of cellular and 'feature' phones in assisting students with self-motivated study at school and at home. It involves developing educational applications which can be used on these devices which, once developed, would be extended to students. Furthermore, this study seeks to investigate the merits of these mobile applications in assisting learners to study. It is my hope that this study can be used to develop the software to make these applications a reality. This study' ultimate purpose is to contribute to vitalizing and energizing mobile education.

• Speech Sciences
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• v.15 no.2
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• pp.79-88
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• 2008

Recently demands for the speech technology-based products targeted for the mobile terminals such as cellular phones and PDA are rapidly increasing. And voting-based speaker identification algorithm is known to have a good performance in the mobile environment, since it works well with small amount of speaker training data. In this paper, we proposed a method to improve the performance of this voting based speaker identification system by using the observation confidence value which is derived from the function of SNR each frame. The proposed method is evaluated with ETRI cellular phone DB which is made for the speaker recognition task. The experimental results show that the proposed method has better performance of 2-3% identification rate than the conventional GMM method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.4 no.4
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• pp.352-356
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• 2003

The current diagnostic monitoring(DM) systems of cellular phones have many problems since their original technology is came from Qualcom company. Therefore the domestic phone makers only modify the source program and use them within limited applications. In this paper, we have developed our own DM system which is enable to solve the above problems and can be used as a test tool so that problems of phone communications are found easily and quickly. In addition, we will enhance this system to follow the current wireless technique by improving the protocol and enhancing the functions.

• Transactions of Materials Processing
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• v.18 no.3
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• pp.245-250
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• 2009

A lid & frame used as the shield of electromagnetic waves in cellular phones are composed of frame, which is welded at their electric circuits, and lid, of which debonding and joining are available from the frame. Typical lid & frame were mechanically bonded by contact between the embossing of lid and the piercing of frame. Bonding force of this part has to allow us to detach the lid from frame for exchange or fix of the electric part and have to be high enough to protect the electric part from external impacts. This study is designed to estimate the effect of design variables of lid & frame on its debonding force. Estimations were performed by finite element method.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.606-615
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• 2003

This study examined the effects of exposure to the electromagnetic field emitted by mobile phone on human cognitive function. Total volunteers were twenty and volunteers were separated in two groups. One is teenager group, and the other is adult group. Test was performed in the counterbalanced order(sham-real, real-sham). Subject remained blind to mobile phone status during the exam. The result showed that the exposure to the electromagnetic field significantly speeded up response time fur teenager group. This results suggest that exposure to the electromagnetic field emitted by cellular phones may have a mild facilitating effect on cognitive function in teenager group.