• Journal of The Korean Association of Information Education
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• v.8 no.1
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• pp.91-99
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• 2004

According to get ubiquitous environment, it is suggested to environment to get information with whichever terminal at any time wherever. Advancement of ability of mobile device increase requirement of wireless internet base solution. In this paper We developed distance education system based on wireless internet. This system has no problem of bandwidth and resolution of pocket pc because of using SWF(Shockwave Flash). It can maintain readability of high quality when size of resolution is changed but another graphic format can't maintain it.

• Journal of Internet Computing and Services
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• v.2 no.3
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• pp.1-8
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• 2001

A school record system by mobile phones is developed using the mobile agent. This developed system support all the wireless protocols by o combined wire and wireless internet Sever for WAP, ME. As a result, it is possible for a student to check his result of achievement and bulletin board by his mobile terminal anywhere, anytime.

• Proceedings of the Korean Information Science Society Conference
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• 2001.10c
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• pp.538-540
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• 2001

인터넷 기술의 발달과 사용자들은 언제 어디서나 원하는 정보를 얻기를 원하게 되었다. 이러한 요구론 배경으로 무선 인터넷 시장은 급속한 발전을 이루고 있다. 그리고 사용자들의 요구도 점차 다양화되고 있는 실정이다. 그로 인해 대표적인 무선 인터넷 기반 언어인 WML(Wireless Markup Language)과 WMLScript를 개발자가 좀 더 실제와 같은 상황에서 편리하게 개발할 수 있는 환경이 필요하게 되었다. 본 논문에서는 CP(Content provider)들이 현실감 있게 무선 컨텐츠를 개발, 브라우징 할 수 있도록 하는 WAP Emulator에서 브라우저의 구조와 WMLScript Interpreter글 포함하고 있는 인터페이스 설계와 구현에 대하여 기술한다.

• Journal of Korea Society of Industrial Information Systems
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• v.19 no.2
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• pp.67-72
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• 2014

Zigbee is a wireless communication technology optimized for Wireless Sensor Network environment. Implementation of location estimation system is based on Zigbee. In this paper, we implement mobile information system using zigbee technology. The proposed system is composed of mobile terminal software and mobile reader softwrae. We also used our hardware in previous system.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.256-264
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• 2015

Energy harvesting devices have been proposed for sensor networking applications where batteries cannot be replaced, and cooperative communication schemes have been used to increase energy efficiency for wireless systems. Here, we develop transmission scheduling schemes for multi-terminal cooperative energy harvesting networks that maximize the packet delivery ratio, i.e., the probability that an event is reported successfully. We see that the proposed scheme provides virtually the same performance as the state-of-the-art threshold-based scheme, but does not require auxiliary parameter optimization. The proposed scheme also permits extensions to multiple cooperating nodes and sources, and it can be modified to accommodate fairness constraints.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.17-18
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• 2007

Mobile WiMAX technology is the key solution for providing high speed internet services at anytime and anywhere in mobile environments as 3.5th wireless technology between 3rd generation and 4th generation wireless technology, and the service demands shall be rapidly increased in future some years. This paper analyzed the QoS performance of Mobile WiMAX technology recommended by IEEE 802.16e specification under the restricted simulation conditions and environments. The major metrics for analyzing QoS performance of Mobile WiMAX are 1) total packet drop rates; 2) transmission / receive packet sizes; 3) end to end delay in node 2; 4) packet drop rate by mobile terminal mobility.

• Journal of electromagnetic engineering and science
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• v.6 no.1
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• pp.10-17
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• 2006

For the sake of the potential ability of overcoming interference in TD-SCDMA(time division-synchronous code division multiple access) systems, pilot signal is adopted, but the presented TD-SCDMA protocol has not considered the Rake technique for their mobile terminals. This paper developed a RAKE receiver algorithm and an implementation circuit, which make use of the pilot signal in the burst structure of the TD-SCDMA base station to estimate main channel parameter(channel delays) in the downlink of TD-SCDMA wireless network. The algorithm can reduce multipath interference for the mobile units in multiusers' case. Theoretic performance analysis presented in the paper and computer simulations show that there is a range of BER for Rake receiver and confirm that the proposed RAKE receiver algorithm achieved a better performance under multipath fading propagation and multiusers conditions.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.447-453
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• 2008

It is decidedly important to ensure QoS(Quality of Service) in order to make it possible a variety of multi-media services and realtime contents services in Wireless networks. One of methods to offer these services is the advanced prediction of Handoff through terminal's directional. In this paper, it is applied that the AP weight for the ground information of peripheral cell and the weight value of history table for the cell frequently visited. Also, it is expected that will be guarant QoS of substantial data in the case of Handoff through exact directional prediction of the next cell by using Kalman Filter algorithm applied GPS coordinates value.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.11a
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• pp.356-357
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• 2007

In this paper, we developed an integrated miniaturized device which acquires and transmits the signal of ECG an interested heartbeat and body's temperature and humidity. Using an amplifier circuit on the electrodes and the radio frequency transmission, the developed system dispenses with the use of cables among the electrodes, amplifier, and the post processing system. The sensor signals are transmitted to the RF-wireless terminal that was developed using the micro controller Aduc812, LCD, RF-module (frequency 424MHz, 9600-bps). In results, the developed system improves not only the signal-to-noise ration in dynamic ECG & and body's temperature and humidity measurement, but also the user convenience.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1138-1144
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• 2008

To study the feasibility of applying wireless communication technology to the control of train for the effective control of train and for the reduction of cost and time to construct the necessary infra structure, we investigate into the application of the existing commercial WCDMA network to CBTC (communication-based train control) to grasp the obstacles and propose the solutions to circumvent them. The obstacles can be categorized into the hand-off problem, the interference problem near the stations, and the problem of radio shadow areas. We propose, as solutions, the cell overlap method and multi-terminal approach for the hand-off problem, the cell sectoring method for the interference problem, and establishment of new base stations along the railroad both to provide the wireless train control and communication service to the customers on the train which was otherwise impossible because of the shadowing effect.