• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.470-472
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• 2006

Sensor networks are the results of convergence of very important technologies such as wireless communication and micro electromechanical systems. In recent years, sensor networks found a wide applicability in various fields such as environment and health, industry scene system monitoring, etc. A very important step for these many applications is pattern classification and recognition of data collected by sensors installed or deployed in different ways. But, pattern classification and recognition are sometimes difficult to perform. Systematic approach to pattern classification based on modem learning techniques like Multivariate Gaussian mixture models, can greatly simplify the process of developing and implementing real-time classification models. This paper proposes a new recognition system which is hierarchically composed of many sensor nodes having the capability of simple processing and wireless communication. The proposed system is able to perform context classification of sensed data using the Multivariate Gaussian function. In order to verify the usefulness of the proposed system, it was applied to intelligent dust collecting system.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.45-54
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• 2009

TETRA(Terrestrial Trunked Radio) is the standard of D-TRS(Digital Trunked Radio System) developed by the ETSI(European Telecommunications Standards Institute). Currently, TETRA has been selected as Electric Power IT Wireless Backbone Network. Traditional distribution automation system has used the wireless network of Mobile Service Provider using CDMA(Code-Division Multiple Access) and WCDMA(Wideband CDMA) modem. Therefore, the development of gateway platform is indispensable according to the change to TETRA network. In this paper, we propose an embedded Linux-based Gateway platform for transmitting Industrial Electric Power IT protocol using TETRA network.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.2
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• pp.170-174
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• 2009

This paper describes the wireless communication test environment for the Link-K system and shows the performance analysis of multiple access protocols. The test environment consists of data generator, modem, radio sets, attenuators, and antennas. In case of both CSMA and Roll-Call protocols, throughput performance and delay are measured. And test results are analyzed. The test results would be used for communication performance analysis and network design of Link-K system.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1431-1433
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• 1999

In this paper, we present diagnosis system for pole and pad transformers using wireless data communication. This system used radio frequency modem for communication between transformer and mobile car. We studied communication's protocol and data frames for operating diagnosis system of distribution transformers

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.312-315
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• 2003

The paper presents a small. unmanned remote controlled probing ship that can reduce the cost for acquiring data of marine and coastal environments. The control system is composed of three microprocessors. one is for overall mission control. another for control of propulsion motors. and the other for sensor operation. For communication system, we adopt direct and indirect methods based on the wireless modem of commercial cellular telephone. The former is a direct communication between the modems of the ship and the server. and the latter is an indirect communication via internet between the ship and the server. The system is equipped with a digital compass and a GPS system for position estimation, and extended Kalman filter is used for the data association. The performance of the ship is demonstrated with the results produced by sets of experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.8 no.2
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• pp.67-73
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• 2008

Reconfigurable radio technology is needed to reconstruct frequency and modem functionality, which can be different within various regions. In addition, it makes it possible for a single mobile handset to support various standards of wireless communication, and thus plays a key role inmobile convergence. A MMIC VCO(Monolithic Microwave Integrated Circuit Voltage Controlled Oscillator) has been developed to produce high power and wide bandwidth that adapts the Clapp-Gouriet type oscillator for series feedback. We were fabricated based on the 0.15um pHEMT from TRW. The MMIC VCO was connected to an alumina substrate on the carrier for testing. This MMIC VCO module shows good performance when compared with existing VCOs. Futhermore, it has potential as a reconfigurable MMIC VCO for ubiquitous communications such as LMDS (Local Multipoint Distribution Service), VSAT, Point to Point Radio and SATCOM.

• Journal of Korea Society of Digital Industry and Information Management
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• v.16 no.1
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• pp.93-98
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• 2020

Research on underwater sensor networks is increasing due to such reasons as marine resource management, maritime disaster prediction and military protection. Many underwater sensor networks performs wireless communication using an acoustic sound wave band signal having a relatively low frequency. So the digital part of their modem can take charge of carrier band signal processing. To enable this, the sampling rate of the baseband band signal should be increased to a sampling rate at which carrier band signal processing is possible. In this paper, we designed a sampling rate increasing circuit based on a CIC interpolator for underwater sensor nodes. The CIC interpolator has a simple circuit structure. However, since the CIC interpolator has a large attenuation of the pass band and a wide transition band, an inverse sinc LPF is added to compensate for frequency response of the CIC interpolator. The proposed interpolator was verified in time domain and frequency domain using ModelSim and Matlab.

• Information and Communications Magazine
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• v.25 no.2
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• pp.6-10
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• 2008

WBAN(Wireless Body Area Network)은 인체를 기준으로 하여 인체내부 및 인체로부터3미터 이내의 무선통신으로 정의하고 있다. 이에따라 WBAN은 현재 다양한 용도로 응용되고 있는데 크게 분류하면 의료용과 비의료용 무선기기로 구분할 수 있다. 즉 가전기기(Comsumer Electronics)들간 의 통신을 목적으로 하는 비의료용 분야와 인체내부에 이식되어 인체내부의 건강상태에 대한 모니터링이나 인체에 이상이 발생시 대처해 주는 인체이식형 무선기기와 인체외부 3미터 이내에서 의료용 sensor로부터 송수신하는 인체외부 기기로 구분할 수 있다. IEEE802.15.6에서 2006년 하반기부터 WBAN(Wireless Body Area Network)시스템에 대한 표준화를 진행하고 있으며, 2008년도에는 표준 제안서를 각국에서 받아 2009년도에 완료할 예정에 있다. 본 고에서는 기존 WBAN으로 사용하고 있던 무선장비들에 대한 각국의 인체내부와 외부의 주파수 분배동향을 분석한 후 WBAN표준화시 대두될 PHY/MODEM/MAC제안에 결정적 영향을 미치는 WBAN의 주파수에 대한 방향을 제시하였다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.539-542
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• 2005

In this paper, we propose a wireless data access system, which used direct sequence spread spectrum method and the ISM band with 900MHz radio frequency. By applying bi-directional transmission between wireless transmitter and receiver, it can be effectively connected with any kinds of RF-ID with 900MHz ISM band. Therefore it could economically be used as peripheral equipments for RF-ID system.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.59-65
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• 2004

The paper presents a small unmanned probing ship that can be used for acquiring information on marine and coastal environments. For communication system, we adopt direct and indirect methods based on the wireless modem of a commercial cellular telephone. The former is a direct communication between the modems of the ship and the server, and the latter is an indirect communication via internet between the ship and the server. The system is equipped with a digital compass and a GPS for position estimation, and extended Kalman filter is used for Navigation. The performance of the ship is demonstrated with the results produced by sets of experiments.