• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.254-262
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• 2013

This paper proposes FMT(Filtered Multi-Tone)-based digital radio implementation algorithms and the results obtained by various field tests especially in terms of transmitter characteristics. In this study, we predefined frame structure and protocols used for the CSTDMA(Carrier Sensing Time Division Multiple Access) scheme, designed digital filters and RF front end to fulfill the system characteristics such as the spectral mask and processing delays given by the Recommendation ITU-R M.1842-1. The proposed system supports exchange of data for e-Navigation with the usage of wider channel of 50-100kHz bandwidth, Turbo coding and FMT modulation. Furthermore, the common Ethernet protocol makes connection to local WLAN(Wireless Local Area Network) on board the ship for other data services.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.2 no.1 s.2
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• pp.93-100
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• 2003

In this farer, An ADSRC(Advanced Dedicated Short Range Communication) packet communication system developed by ETRI is introduced. The ADSRC system has been developed to provide high-speed, short-range wireless racket communication in roadside environment for mobile office services. The requirements of the ADSRC system for mobile office services and the system design specification to meet them with regard to mobile of nce environment are discussed. The ADSRC packet communication systems consist of the MAC(Medium Access Control) Processor block the OFDM() modem block and the RF block. The MAC processor block handles medium access control. The OFDM modem transmits data packets at up to 24Mbps adaptively and recovers the data from RF block. The ADSRC packet communication system architecture is described.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.25-28
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• 2010

The need for multiband RF front-end in modern communication system is growing rapidly. For example, satellite system always uses a complex arrangement of frequency plans and consequently needs filters for each communication channel and it will be ideal to have a single filter module that does jobs of all those channel filters to reduce the size and payload of the system. In this paper, a new method to transform four-port self-feedback balanced dual-band bandpass filter into two-port is proposed. The two-port balanced dual-band bandpass filter which has baluns at the input and output ports and the fundamental frequency at 2.5 GHz and the first harmonic frequency at 5.7 GHz is fabricated and measured. Good agreement between measured and simulated results was achieved.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.7
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• pp.1534-1540
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• 2005

The direct conversion method is classified into the structure using the mixing technology and six-port scheme. In the view point of complexity and integration the direct conversion method using the six-port scheme is superior to that with mixing technology. Expecially, the six-port direct conversion technology provides the low power consumption and the broad-band characteristic. In this paper, the six-port direct conversion receiver with the branch-line coupler and the ring hybrid coupler is desisted respectively. The performances of the designed six-port schemes are analyzed and the six-port scheme with superior performance characteristics is proposed.

• Journal of the Korean Chemical Society
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• v.3 no.1
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• pp.23-27
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• 1954

The relation between the height of ascending solvents and its velocity were studied with strips of Toyo No. 50 filter paper. The filter paper strip of 3cm width and cat 30 cm length is hooked down or fixed between two sheets of glass plates inside a cylinder containing the solvent, in which the lower end of the strip is dipped. As the solvents, acetone, hydrochloric acid, water or mixtures of these are used. For short time intervals, Ostwald's folmula $h = Kt^n$ was found to be most suitable to express the relation between the height of the solvent front, h, and time, t. For longer time intervals, results will be discussed in the next paper. The mean values of the constant m in the above formula for pure acetone and pure water were 0.44 and 0.485, respectively, and that of K were 0.05 and 2.4, respectively. The time interval whose the above formula applies, for each solvent was 2 hours for the former, and a half hour for the later, respectively. The movement of solutes, such as $Cu^{++}$ and $Fe^{++}$ showed that the Rf values of solutes become constant values after a long periods; e.g., ca. 6 hours with 10N-HCl-Acetone (1 : 9) solvent.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.97-101
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• 2011

Quad band p-HEMT SP6T switch for handset applications was developed. To achieve the low insertion loss and high isolation, trade-off between "On" state and "Off" state was considered by optimization of unit cell. Especially, in case isolation between transmit port and receive port, it was achieved by large capacitors and miniaturization of chip size was achieved by common voltage control and ground using back via process. Designed SP6T switch has size of $950um{\times}100um$ and take into consideration the gate recess error, excellent loss and isolation was confirmed in operating frequency.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.295-301
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• 2011

A triple-band transceiver module for 2.3/2.5/3.5 GHz mobile WiMAX, IEEE 802.16e, applications is introduced. The suggested transceiver module consists of RFIC, reconfigurable/multi-resonance MIMO antenna, embedded PCB, mobile WiMAX base band, memory and channel selection front-end module. The RFIC is fabricated in $0.13{\mu}m$ RF CMOS process and has 3.5 dB noise figure(NF) of receiver and 1 dBm maximum power of transmitter with 68-pin QFN package, $8{\times}8\;mm^2$ area. The area reduction of transceiver module is achieved by using embedded PCB which decreases area by 9% of the area of transceiver module with normal PCB. The developed triple-band mobile WiMAX transceiver module is tested by performing radio conformance test(RCT) and measuring carrier to interference plus noise ratio (CINR) and received signal strength indication (RSSI) in each 2.3/2.5/3.5 GHz frequency.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1058-1063
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• 2010

In this paper, we designed self-frequency synchronizing circuit using image rejection mixer(IRM) and single-sideband(SSB) up-converter which can effectively eliminate the image frequencies occurred in multi-channel super-heterodyne receivers and help us to match inter-channel phase. Also the self-frequency synchronizing circuit simplifies system because there need no extra devices for making intermediate frequency(IF) by creating the local signal within several nanoseconds by means of generating the same frequency of IF signal and modulating radio frequency(RF) signal. We adopt the limiting amplifier for the purpose of protecting the circuit from spurious signals which come from the front end side having wide instantaneous bandwidth characteristics and constantly injecting same level into the input local signal of IRM. The IRM we fabricated has image rejection ratio of 27dB, which is good over 7dB for foreign company's. Also, the SSB up-converter we fabricated has 1dB compression point of 18dBm, which is good over 16dB for foreign company's. And the size is compact about one-forth.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.481-484
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• 2005

The direct conversion method is classified into the structure using the mixing technology and six-port scheme. In the view point of complexity and integration the direct conversion method using the six-port scheme is superior to that with mixing technology. Expecially, the six-port direct conversion technology provides the low power consumption and the broad-band characteristic. In this paper, the six-port direct conversion receiver with the branch-line coupler and the ring hybrid coupler is designed respectively. The performances of the designed six-port schemes are analyzed and the six-port scheme with superior performance characteristics is proposed.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.297-302
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• 2002

The subsystems of two channel correlation radiometer such as RF front-end, IF and LF unit, LO unit, software based I/Q demodulator and complex correlator are characterized and their performance is analyzed in this paper. The limited hardware calibration method and receiver design consideration are discussed. The receiver architecture of 37GHz correlation radiometer is integrated. The designed radiometer employs a single-sideband superheterodyne receiver. The center frequency of the radiometer is 37 GHz and IF center frequency is 1.95 GHz with the equivalent noise bandwidth of 79.6 MHz. The receiver has less than 4.2 dB noise figure which is calculated by the Y-factor method and its gain can be adjusted from 60 dB to 80 dB.