• The Journal of the Korea Contents Association
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• 제11권12호
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• pp.639-648
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• 2011

Since the emergence of the smartphone and tablet PC whose wireless internet accessibility has improved, personal computing environment has shifted from PCs to mobile web based mobile devices, and therefore the use of information and the communication method have been changing rapidly. Under the circumstance, domestic universities have actively been establishing mobile websites for smartphone users. Such mobile websites, however, focused on diverse functions and a showy design rather than on usability or accessibility, and were developed simply for the purpose of public relations. For this reason, students are now faced with difficulties in using the websites. Therefore, this paper proposes a novel web interface with the consideration of usability and accessibility in order for users to easily use and assess proper information. The matters to be taken into account in developing a mobile website are an intuitive interface design, user experiences, a user customized interface and compliance with web standards.

• Korean Journal of Cognitive Science
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• 제12권4호
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• pp.1-9
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• 2001

Mobile Internet can be used anytime and anyplace thanks to the portability of mobile phones and wireless connectivity to the Internet. Therefore Mobile Internet users can be in various contexts compared with Wire Internet users in stationary contexts. In this research out of various context attributes, we selected physical context attributes of hands feet and eyes and studied how these affect the performance of Internet use and user\\` satisfaction. For this research we made control1ed experiments in performing the given task in each attribute and measured the task accuracy and the subjective satisfaction. The experiments indicated that each attribute doesn\\`t affect the accuracy and satisfaction when it is given individually but when two of more context attributes are given simultaneously in context of disturbance of eyes and motion of legs the accuracy and satisfaction declines. This suggests that the subjects need more attention for the physical context of two or more factors than one factor because of the attention capacity limit. As the result, the attention capacity for the task shrinks.

• Journal of Advanced Navigation Technology
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• 제13권5호
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• pp.787-792
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• 2009

A number of very promising applications such as health monitoring and U-Health of ubiquitous techniques has attracted interest in recent years. Because it can observes the condition of patient from long distance using the equipment which combines with radio communication and medical monitoring system. If it is at emergency situation, it can disposes the condition of the patient. In this paper, we propose the new data format and the transmission communication system of combination medical information with the bluetooth. And we produce the on-board system which transmits the medical information. This system integrated the blood pressure and glucose monitor of personal medical equipment, and the medical information which obtained from on-board system acquires through the gateway with the bluetooth. Medical information is transmitted to the tele-monitor server by the wireline network. We evaluated the proposed system under the laboratory environment and confirmed the excellent performance of transmission of the medical information.

• Journal of Korea Multimedia Society
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• 제12권2호
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• pp.257-271
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• 2009

In this paper, we propose a protocol compression scheme for enhancing the performance of call processing of PTT(Push-to-Talk) which is one of the important services in IMS(IP Multimedia Subsystem), a next generation integrated wired/wireless packet communication network. To service the PTT on an IMS network, it should use the same call setup procedure as legacy Mobile and TRS(Trunked Radio System) networks and have a fast call setup time and enough communication bandwidth because a number of terminals should be able to exchange same data in real time. The proposed A+SigComp scheme reduces the initial call setup delay of SIP by about 10%, which is used by PTT service for call setup. In addition, the A+ROHC scheme is proposed to compress the header of RTP packets transferred during PTT voice transmission and, as a result, about 5% of increase in communication efficiency is observed.

• Journal of Advanced Navigation Technology
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• 제20권1호
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• pp.45-52
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• 2016

In this paper, the method of interference analysis and its simulation have been suggested for the frequency sharing between aeronautical radio navigation systems and Link-16 platforms. In order to get the criteria for interoperability, the algorithm of interference analysis and protection ratio are derived to assure frequency sharing. Also the receiving power of wireless system has been illustrated with the help of radio propagation model of ITU-R Rec. P.1546 in VHF-UHF band. Finally the required receiving power or separation distance between DME/TACAN beacons and Link-16 ground station terminals has been considered based on system link budget in terms of evaluating interoperability as well as actual applications. As a result, if the suggested interference analysis and test set-up are applied to the field trial, it will lead to easy means to make a decision on interoperability over the existing incumbent systems.

• Journal of Advanced Navigation Technology
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• 제13권1호
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• pp.87-96
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• 2009

The purpose of this paper is to analyze the power control problem in wireless communications with game theoretic approach. The major contribution of the present paper is that we formulated the problem as a game with a finite number of strategies while most of the previous game theoretic power control literatures modeled with continuous game in which there are infinite number of strategies. It should be noted that the closed-loop power control would be performed in a discrete manner, power up or down from the present level of power with fixed power control step size. We model the current closed-loop power control scheme with the famous Prisoner's dilemma model and show that the power-up strategy is Nash equilibrium. That is, every mobile tries to increase their power and approach to their maximal power. Thus, the outcome of current power control (Nash equilibrium) is inefficient. In order to attain efficient power control for the environment where ICI(Inter-Cell Interference is severe, we developed a new payoff function in which the penalty mechanism is introduced and derived conditions under which power-down becomes Nash equilibrium strategy for all players. Furthermore we examined the trajectory of equilibrium power when the power control game will be played repeatedly.

• Journal of Advanced Navigation Technology
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• 제13권1호
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• pp.11-18
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• 2009

As a marine leisure industry has being developed and demands for leisure culture have rapidly increased, the needs for services offering marine safety and related information are growing. Accordingly, in the study I developed the contents providing server to support this with ENC agent who presents geographical information of digitalized Electronic Nautical Chart satisfying with the standard(S-57) by International Hydrographic Organization and a web searching agent who builds a database by collecting marine-related information in order to provide a variety of realtime information such as weather, fishing and news. In addition, I designed and embodied network based mobile contents which can be presented on a WIPI(Wireless Internet Platform for Interoperability) based portable handset by receiving an ENC and other processed information from server. With the results produced by such experiments, I measured a compressibility corresponding to a image compression format of electronic nautical chart transmitted and analyzed the correlation between increase in packets of requested information and the cost.

• Journal of Advanced Navigation Technology
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• 제24권2호
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• pp.142-147
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• 2020

In the present study, we proposed newly a CPW-fed miniaturized folded-slot antenna with open ended slot for WCDMA (1.92 ~ 2.17 GHz) band. Open-ended slots and asymmetric ground plane are used for a miniaturization of the antenna, and the proposed antenna was designed and fabricated on a FR-4 substrate with dielectric constant 4.3, thickness of 1.6 mm, and size of 35×70 ㎟. The measured impedance bandwidths (|S₁₁| ≤ -10 dB) of fabricated antenna is about 400 MHz (1.86 ~ 2.26 GHz), which sufficiently satisfied interested band. Furthermore, the gain of antenna is 2 dBi and this antenna shows a similar radiation patterns of the dipole antenna. Therefore, it is expected to be used usefully in wireless and mobile communication device.

• Journal of Service Research and Studies
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• 제3권2호
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• pp.19-32
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• 2013

An explosive growth of mobile devices and smart phones, such as Tablet PC using wireless Internet, is changing the Information environment rapidly. Smart technology telecommuting work or smart work centers, mobile devices, and configure your environment to take advantage of remote collaboration. Also, you do not have the limitations of time and space provides a flexible working environment. Smartwork environment is an IT environment to be provided to carry out the business by accessing remotely via smart device outside of the internal IT infrastructure of an existing. Smartwork system to increase the work efficiency is present to what information protection threats according to their convenience. Safeguards information that can be utilized to build a secure smartwork environment is required. Therefore, in this paper, we examined the worksmart information protection measures that can protect the information be reconciled smoothly to fit the smartwork environment.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제28권1호
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• pp.76-79
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• 2017

This paper presents the electromagnetic shielding structure for low frequency wireless power transfer system with magnetic induction method using soft magnetic materials. Soft magnetic materials have advantages such as high permeability and low magnetic loss, but have undesirable effect of power loss by eddy current. To overcome this, we proposed the patterned soft magnetic material to suppress the eddy current path. For validity of this paper, we simulated the coil transfer efficiency and the radiated electromagnetic field, and fabricated the proposed structure using 79-permalloy. The measured results shows good agreements with the simulated results and reduction of the radiated electromagnetic field compared to commercial ferrite plate.