• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.31-37
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• 2010

Shape conversion coefficient and equivalent diameter for changing 2D image to 3D image by the Digital Image Process(DIP) have been suggested and modified particle size distribution curve has been showed. Couple of aggregates, like two different marine aggregates and two different crushed stones, have been employed. The measured flatness ratios of each aggregate were 0.30, 0.36, 0.47 and 0.83, respectively. Also, the conversion shape coefficients of each aggregate were determinded as 0.77, 0.78, 0.84 and 0.92. The size of aggregate has been modified by multiplying the shape conversion coefficient and the aggregate size from DIP. The modified gradation curve with modified volume and weight of aggregate has been suggested. Within the limited test results, DIP is one of useful to get the particle shape of aggregate with limitation of measuring errors and to apply the particle distribution curve.

• ETRI Journal
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• v.29 no.4
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• pp.421-429
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• 2007

This paper presents a direct-conversion CMOS transceiver for fully digital DS-UWB systems. The transceiver includes all of the radio building blocks, such as a T/R switch, a low noise amplifier, an I/Q demodulator, a low pass filter, a variable gain amplifier as a receiver, the same receiver blocks as a transmitter including a phase-locked loop (PLL), and a voltage controlled oscillator (VCO). A single-ended-to-differential converter is implemented in the down-conversion mixer and a differential-to-single-ended converter is implemented in the driver amplifier stage. The chip is fabricated on a 9.0 $mm^2$ die using standard 0.18 ${\mu}m$ CMOS technology and a 64-pin MicroLead Frame package. Experimental results show the total current consumption is 143 mA including the PLL and VCO. The chip has a 3.5 dB receiver gain flatness at the 660 MHz bandwidth. These results indicate that the architecture and circuits are adaptable to the implementation of a wideband, low-power, and high-speed wireless personal area network.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.1
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• pp.90-98
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• 1999

This paper presents a wideband single-balanced mixer using a diode which can be used in RF receiver of microwave measurement systems. For wideband characteristic, local oscillator(LO) signal is provided to diode with low loss using a coplanar waveguide-to-slotline balun. For high isolation characteristic radio frequency (RF) port and intermediate frequency (IF) port are designed using directional coupler. This mixer presents 30.5~31.17dB conversion loss whose flatness is within 1dB for 9 kHz~2.6 GHz wideband RF signal, and above 30 dB isolation for LO signal.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.2
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• pp.302-312
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• 2000

Digital TV tuner for 8-VSB modulation was developed with satisfying the requirements of ATSC. Double frequency conversion and active tracking filter was used in order to suppress IF beat and image band, which results in reducing the interference between adjacent channels and multi-channels. The implemented digital TV tuner has excellent performance such as the wide dynamic range, good flatness in passing band, and low phase noise. The developed tuner is available to handle the digital and analogue television signal at the same time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.607-610
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• 2006

The Digital Frequency Synthesizer(DFS) that generates the wideband signal with hish speed frequency hopping rate and high frequency resolution characteristics was implemented in this paper. The DFS was applied as local oscillator for direct frequency conversion IF modules of DVB-RCS, which directly generates the transmission immediate frequency signal by using DDS and wideband PLL technologies. The DDS technology provides high speed frequency hopping rate and high frequency resolution characteristics, which ate also the DVB-RCS requirement. The wideband PLL technology also provides the wideband signal generation, which is a necessity for direct frequency conversion modules. The implemented DFS provide the spurious suppression characteristic of -50 dBc, frequency resolution of 0.233 Hz and frequency hopping rate of 125 ns, respectively. Also the DFS represent the amplitude flatness of 3 dB and less in the pass-band and phase noise characteristic of -75 dBc/Hz at 1 kHz frequency offset.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.2
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• pp.223-228
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• 2007

The Digital Frequency Synthesizer(DFS) that generates the wideband signal with high speed frequency hopping rate and high frequency resolution characteristics was designed and implemented in this paper The DFS was applied as local oscillator for direct frequency conversion IF modules of DVB-RCS, which directly generates the transmission immediate frequency signal by using DDS and wideband PLL technologies. The DDS technology provides high speed frequency hopping rate and high frequency resolution characteristics, which are also the DVB-RCS requirement. The wideband PLL technology also provides the wideband signal generation, which is a necessity for direct frequency conversion modules. The implemented DFS provides the spurious suppression characteristic of -50 dBc and less, frequency resolution of 0.233 Hz and frequency hopping rate of 125 ns, respectively. Also the DFS represents the amplitude flatness of 3 dB and less in the pass-band, and phase noise characteristic of -75 dBc/Hz at 1 kHz frequency offset.

• Journal of the Optical Society of Korea
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• v.19 no.1
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• pp.7-12
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• 2015

Up to ${\sim}520{\mu}J$ broadband mid-infrared (IR) supercontinuum (SC) generation in telecommunication multimode fiber (MMF) directly pumped by a $2.054{\mu}m$ nanosecond Q-switched Tm, $Ho:YVO_4$ laser is demonstrated. An average output power of 3.64 W is obtained in the band of ~1900 to ~2600 nm, and the corresponding optic-to-optic conversion efficiency is 67% by considering the coupling efficiency. The spectrum has extremely high flatness with negligible intensity variation (<2%) in the wavelength interval of ~2070 to ~2475 nm. The SC long-wavelength edge is limited by the silicon glass material loss, and by optimizing the MMF length, the SC spectrum could extend out to ${\sim}2.6{\mu}m$. The output SC pulse shapes are measured at different output powers, and no splits are found. The SC laser beam is nearly diffraction limited with an $M^2=1.15$ in $2.1{\mu}m$ measured by the traveling knife-edge method, and the laser beam spot is monitored by an infrared vidicon camera.

• ETRI Journal
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• v.34 no.4
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• pp.485-491
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• 2012

In this paper, the implementations of a $0.1{\mu}m$ gallium arsenide (GaAs) pseudomorphic high electron mobility transistor process for a low noise amplifier (LNA), a subharmonically pumped (SHP) mixer, and a single-chip receiver for 70/80 GHz point-to-point communications are presented. To obtain high-gain performance and good flatness for a 15 GHz (71 GHz to 86 GHz) wideband LNA, a five-stage input/output port transmission line matching method is used. To decrease the package loss and cost, 2nd and 4th SHP mixers were designed. From the measured results, the five-stage LNA shows a gain of 23 dB and a noise figure of 4.5 dB. The 2nd and 4th SHP mixers show conversion losses of 12 dB and 17 dB and input P1dB of -1.5 dBm to 1.5 dBm. Finally, a single-chip receiver based on the 4th SHP mixer shows a gain of 6 dB, a noise figure of 6 dB, and an input P1dB of -21 dBm.

• The Journal of the Korea institute of electronic communication sciences
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• v.1 no.1
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• pp.8-19
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• 2006

The RF Module which can be adjusted for a digital terrestrial and multi standard(DVB-C, ISDB-T, DVB-H) reception is developed. The Module by single conversion does divide a broadband(45MHz~860MHz) broadcasting channels into three-bands(UHF, VHF_HIGH, VHF_LOW) to satisfy some electrical performances such as image signal rejection, phase noise, IF flatness etc and digital reception specifications such as analog and digital adjacent channel protection, co-channel protection which is important in environment with co-existence both analog and digital broadcasting systems.

• Journal of electromagnetic engineering and science
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• v.16 no.1
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• pp.7-12
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• 2016

This paper presents the design of a negative group delay circuit (NGDC) using the filter synthesis approach. The proposed design method is based on a frequency transformation from a low-pass filter (LPF) to a bandstop filter (BSF). The predefined negative group delay (NGD) can be obtained by inserting resistors into resonators. To implement a circuit with a distributed transmission line, a circuit conversion technique is employed. Both theoretical and experimental results are provided for validating of the proposed approach. For NGD bandwidth and magnitude flatness enhancements, two second-order NGDCs with slightly different center frequencies are cascaded. In the experiment, group delay of $5.9{\pm}0.5ns$ and insertion loss of $39.95{\pm}0.5dB$ are obtained in the frequency range of 1.935-2.001 GHz.