• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.132-135
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• 2002

In radio communication technology, SDR(Software Defined Radio) technology is emerging as a trendy technology for future. SDR is expected to change existing radio systems including central hardware. SDR is equipment that wireless parameters (frequency, modulation, additional service, power level, receive sensitivity, etc.) are controlled by software. In the world, equipments using the new technology are spreading. Not only equipments being imported but also local manufacturers are making this equipment, developing software and offering upgraded service. In the future, as SDR spreads and users choose the service, diverse equipments will be developed through competition and individual development. This diversity of equipment and services will introduce problems in compatibility and interoperation issues. So the government will have to make technical standard for SDR service and will have to make theses standards available to users and manufacturers alike. Therefore I am investigating the elements that can be used to establish these standards.

• Journal of the Korean Society for Heat Treatment
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• v.25 no.6
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• pp.279-282
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• 2012

$SnO_2$ thin films were prepared on the Si substrate by radio frequency (RF) magnetron sputtering and then surface of the films were irradiated with intense Ar ion beam to investigate the effect of Ar ion irradiation on the properties and hydrogen gas sensitivity of the films. From atomic force microscope observation, it is supposed that intense Ar bombardments promote rough surface and increase gas sensitivity of $SnO_2$ films for hydrogen gas. The films that Ar ion beam irradiated at 6 keV show the higher sensitivity than the films were irradiated at 3 keV and 9 keV. These results suggest that the $SnO_2$ thin films irradiated with optimized Ar ion beam are promising for practical high-performance hydrogen gas sensors.

• Korean Journal of Materials Research
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• v.20 no.5
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• pp.267-270
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• 2010

Sn doped $In_2O_3$ (ITO) and ITO/Cu/ITO (ICI) multilayer films were prepared on glass substrates with a reactive radio frequency (RF) magnetron sputter without intentional substrate heating, and then the influence of the Cu interlayer on the methanol gas sensitivity of the ICI films were considered. Although both ITO and ICI film sensors had the same thickness of 100 nm, the ICI sensors had a sandwich structure of ITO 50 nm/Cu 5 nm/ITO 45 nm. The ICI films showed a ten times higher carrier density than that of the pure ITO films. However, the Cu interlayer may also have caused the decrement of carrier mobility because the interfaces between the ITO and Cu interlayer acted as a barrier to carrier movement. Although the ICI films had two times a lower mobility than that of the pure ITO films, the ICI films had a higher conductivity of $3.6{\cdot}10^{-4}\;{\Omega}cm$ due to a higher carrier density. The changes in the sensitivity of the film sensors caused by methanol gas ranging from 50 to 500 ppm were measured at room temperature. The ICI sensors showed a higher gas sensitivity than that of the ITO single layer sensors. Finally, it can be concluded that the ICI film sensors have the potential to be used as improved methanol gas sensors.

• Korean Journal of Optics and Photonics
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• v.19 no.5
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• pp.343-348
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• 2008

This study was carried out to commercialize FTTH by developing a burst mode optical receiver for E-PON. The optical receiver was manufactured by minimizing the capacitance of a photodiode to improve sensitivity for meeting 10, 20 km OLT Rx standard of E-PON at the transmission speed of 1.25 Gb/s. When bit-error ratio is $10^{-12}$ and PRBS is $2^5-1$, sensitivity is -26 dBm, loud/soft ratio is 23 dB. Both preamble time and guard time were set to 102.4 ns (128 bit). After comparing a photodiode whose capacitance is 0.53 pF with another photodiode whose capacitance has been minimized to 0.26 pF, we could see that sensitivity improved to 0.7 dBm and so did bandwidth to 190 MHz of burst mode for the optical receiver manufactured by the photodiode whose capacitance is 0.26 pF.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.1045-1050
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• 2008

In this paper presents a CMOS RF receiver for IR-UWB wireless communications is presented. The impulse radio based UWB receiver adopts the non-coherent demodulation that simplifies the receiver architecture and reduces power consumption. The IR-UWB receiver consists of LNA, envelop detector, VGA, and comparator and the receiver including envelope detector, VGA, and comparator is fabricated on a single chip using $0.18{\mu}m$ CMOS technology. The measured sensitivity of IR-UWB receiver is down to -70 dBm and the BER $10^{-3}$, respectively at data rate 1 Mbps. The current consumption of IR-UWB receiver except external LNA is 5 mA at 1.8 V.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.858-867
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• 2011

In this paper, we propose a microwave radiometer for remote sensing of oil spills on the water surface. In order to achieve the development aim of the measurement accuracy within 0.2 mm for oil slicks of 0~4 mm thickness, the requirements of the microwave radiometer and the specifications of its receiver are drawn. From these requirements and specifications, the receiver with high gain, high sensitivity is designed and implemented. The receiver has the bandwidth of 58 MHz, the system gain of 47.3 dB and the sensitivity of 0.46 K at 10.65 GHz. The processes of design and implementation of the receiver are described in this paper. The effectiveness of the proposed microwave radiometer in the measurement of oil slicks is demonstrated experimentally. The results show the microwave radiometer can detect the oil slicks for 0~5 mm thickness within the accuracy of 0.13 mm successfully.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.11
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• pp.1130-1137
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• 2009

This paper proposes a new clock routing design for suppressing clock harmonic effects in a Printed Circuit Board (PCB) for a terrestrial Digital Multimedia Broadcasting(DMB) system. Typical crystal reference frequencies that are widely used in DMB tuners are 16.384 MHz, 19.2 MHz, 24.576 MHz. When the high-order harmonic components of these reference frequencies fall near the RF channel frequencies, receiver sensitivity of the tuners is seriously degraded. In this work, we propose a new clock routing design in order to address the clock harmonic coupling issue. The proposed design incorporates two inductors for isolating the clock ground from the main ground, and adopts a new strip line-style routing instead of the conventional microstrip line style routing to minimize the overlap area with the main ground. As a result, the RF sensitivity of the T-DMB tuner is improved by 2 dB.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.462-469
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• 2008

In this paper, we design the FPGA (Field-Programmable Gate Array) of the KOINONIA WPAN (Wireless Personal Area Network), and implement the SoC (System on Chip). We use the redundant bits to make a constant-amplitude in a modulator part. Additionally, the SNR (Signal to Noise Ratio) performance of the demodulator is improved by using the redundant bits in decoding steps. The four-million FPGA of the KOINONIA WPAN can be operated at 44MHz frequency. The PER (Packet Error Rate) of the designed FPGA with RF (Radio Frequency) module is below 1% at the -86dB MIPLS (Minimum Input Power Level Sensitivity), and the SNR is about 13dB. The SoC is implemented by using Hynix 0.25um CMOS (Complementary Metal Oxide Semiconductor) process. The size of the SoC is $6.52mm{\times}6.92mm$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1107-1115
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• 2012

This paper presents the development processes of a microwave radiometer for remote sensing of water surface temperature. Achieving the measurement accuracy within $2^{\circ}C$ for water surface temperature of $5{\sim}30^{\circ}C$, the requirements and specifications of the microwave radiometer and its receiver are drawn. The receiver with high gain, high sensitivity is designed and implemented. The receiver has the bandwidth of 50 MHz, the system gain of 45.2 dB and the sensitivity of 0.56K at 5.02 GHz. The effectiveness of the developed microwave radiometer in the measurement of water surface temperature is demonstrated experimentally. The results show the microwave radiometer can detect water surface temperature for $7.5{\sim}18^{\circ}C$ within the accuracy of $0.45^{\circ}C$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.900-907
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• 2013

The development processes of a L-band microwave radiometer for remote sensing of water surface salinity are described in this paper. Achieving the development aim of the measurement accuracy within 2 psu for water surface salinity of 0~40 psu, the requirements and specifications of the microwave radiometer and its receiver are drawn. The receiver with high gain, high sensitivity is designed and implemented to satisfy these requirements and specifications. The receiver has the bandwidth of 45 MHz, the system gain of 47 dB and the sensitivity of 0.41 K at 1,390 MHz. The effectiveness of the developed L-band microwave radiometer for remote sensing of water surface salinity is demonstrated experimentally. The results show the microwave radiometer can detect water surface salinity for 10~28 psu within the accuracy of 1.4 psu.