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Byungjoon Kim,Jong-seop Koo,Duksoo Kim,Sangwook Nam IEEE 2017 IEEE geoscience and remote sensing letters Vol.14 No.4
<P>This letter proposes a novel frequency-modulated continuous-wave radar to achieve high wall-clutter rejection with a low-order high-pass filter (HPF). The proposed radar has two phase-locked loops (PLLs) and a phase controller. One transmitter PLL generates a chirp signal for transmitting (TX chirp) signal, the other a local-oscillator (LO) PLL generates a chirp signal for mixing (LO chirp), and the phase controller controls a phase of a reference clock entering the transmitter PLL. When the phase controller advances by a half-period of the reference clock, the PLL tracks and locks onto the advanced reference clock, and the TX chirp signal is advanced by a half-period of the reference clock. If longer advanced time is needed, the above-mentioned process (advance, track, and lock) is repeated after PLL locking. In this manner, long advanced time can be achieved with a fine time-resolution. The use of appropriate advanced time decreases the time gap between a wall-reflection signal and the LO chirp signal, and increases the ratio of target beat-frequency to wall beat-frequency. This enables a low-order HPF to fully attenuate wall-clutter. Moreover, this technique decouples the relationship between the wall's distance and the HPF's cut-off frequency. The radar was implemented and measured. The wall was located at 1.5 m and the target was located at 3 m. The measured results show that a second-order HPF attenuates by more than 20 dB for the wall beat-frequency signal, while it does not attenuate the target beat-frequency signal.</P>
CMOS Linear Power Amplifier with Envelope Tracking Operation
Byungjoon Park,Jooseung Kim,Yunsung Cho,Sangsu Jin,Daehyun Kang,Bumman Kim 한국전자파학회JEES 2014 Journal of Electromagnetic Engineering and Science Vol.14 No.1
A differential-cascode CMOS power amplifier (PA) with a supply modulator for envelope tracking (ET) has been implemented by 0.18 μm RF CMOS technology. The loss at the output is minimized by implementing the output transformer on a FR-4 printed circuit board (PCB). The CMOS PA utilizes the 2<SUP>nd</SUP> harmonic short at the input to enhance the linearity. The measurement was done by the 10MHz bandwidth 16QAM 6.88 dB peak-to-average power ratio long-term evolution (LTE) signal at 1.85 GHz. The ET operation of the CMOS PA with the supply modulator enhances the power-added efficiency (PAE) by 2.5, to 10% over the stand-alone CMOS PA for the LTE signal. The ET PA achieves a PAE of 36.5% and an ACLRE-UTRA of ?32.7 dBc at an average output power of 27 dBm.
A High Gain and High Harmonic Rejection LNA Using High Q Series Resonance Technique for SDR Receiver
Byungjoon Kim,Duksoo Kim,Sangwook Nam 한국전자파학회JEES 2014 Journal of Electromagnetic Engineering and Science Vol.14 No.2
This paper presents a high gain and high harmonic rejection low-noise amplifier (LNA) for software-defined radio receiver. This LNA exploits the high quality factor (Q) series resonance technique. High Q series resonance can amplify the in-band signal voltage and attenuate the out-band signals. This is achieved by a source impedance transformation. This technique does not consume power and can easily support multiband operation. The chip is fabricated in a 0.13-μm CMOS. It supports four bands (640, 710, 830, and 1,070MHz). The measured forward gain (S21) is between 12.1 and 17.4 dB and the noise figure is between 2.7 and 3.3 dB. The IIP3 measures between - 5.7 and - 10.8 dBm, and the third harmonic rejection ratios are more than 30 dB. The LNA consumes 9.6 mW from a 1.2-V supply.
Inactivation of Salmonella on Eggshells by Chlorine Dioxide Gas
Kim, Hyobi,Yum, Bora,Yoon, Sung-Sik,Song, Kyoung-Ju,Kim, Jong-Rak,Myeong, Donghoon,Chang, Byungjoon,Choe, Nong-Hoon Korean Society for Food Science of Animal Resource 2016 한국축산식품학회지 Vol.36 No.1
Microbiological contamination of eggs should be prevented in the poultry industry, as poultry is one of the major reservoirs of human Salmonella. ClO<sub>2</sub> gas has been reported to be an effective disinfectant in various industry fields, particularly the food industry. The aims of this study were to evaluate the antimicrobial effect of chlorine dioxide gas on two strains of Salmonella inoculated onto eggshells under various experimental conditions including concentrations, contact time, humidity, and percentage organic matter. As a result, it was shown that chlorine dioxide gas under wet conditions was more effective in inactivating Salmonella Enteritidis and Salmonella Gallinarum compared to that under dry conditions independently of the presence of organic matter (yeast extract). Under wet conditions, a greater than 4 log reduction in bacterial populations was achieved after 30 min of exposure to ClO<sub>2</sub> each at 20 ppm, 40 ppm, and 80 ppm against S. Enteritidis; 40 ppm and 80 ppm against S. Gallinarum. These results suggest that chlorine dioxide gas is an effective agent for controlling Salmonella, the most prevalent contaminant in the egg industry.
Design of Wideband Coupled Line DC Block with Compact Size
KIM, Byungjoon,NAM, Sangwook,AHN, Hee-Ran,SONG, Jae-Hoon 'Institute of Electronics, Information and Communi 2014 IEICE transactions on electronics Vol.97 No.9
<P>This letter proposes a wideband compact DC block design technique. This DC block has a wide pass-band and wide stop-band and transforms termination impedances. It comprises a pair of coupled lines on a defected ground structure (DGS) with capacitor loading. A periodic DGS pattern increases coupling, and, consequently, a wideband DC block design is allowed with a microstrip process on a high dielectric low height substrate. A DC block with equal termination impedances of 50 Omega and another that transforms 50 into 30 Omega are fabricated. The measured fractional bandwidths are 48% and 47%. The size of the DC block is 16.8 x 15 mm(2) (0.057 lambda(0) x 0.051 lambda(0)).</P>
Kim, Hyobi,Lee, Jiyoung,Jang, Yangho,Chang, Byungjoon,Kim, Aeran,Choe, Nonghoon The Korean Society of Veterinary Science 2016 大韓獸醫學會誌 Vol.56 No.2
This study was conducted to investigate the prevalence and antimicrobial resistance of Salmonella spp. and Escherichia (E.) coli isolated from ducks in Korea. A total of 400 cecal content samples were collected from 40 duck farms in Korea. Isolated Salmonella spp. and E. coli strains were 83 and 364 of the 400 cecal samples, respectively. The most prevalent serotype among the 83 Salmonella isolates was Salmonella Typhimurium (51 isolates: 61.45%). Resistance to the tested antimicrobial agents by Salmonella isolates was low except for erythromycin, while the resistance of the E. coli isolates to the other tested antimicrobial agents was high and 90.9% (331/364) of E. coli isolates showed multi-antimicrobial resistance. Antimicrobial resistance in duck zoonotic pathogens should be of concern to the Korean duck industry, as these pathogens exhibit a high rate of antimicrobial resistance and pose a potential hazard to public health.