• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1035-1039
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• 2012

In this paper, we developed a 94 GHz waveguide VCO(voltage controlled oscillator) using a GaAs-based Gunn diode and a varactor diode. The cavity is designed for fundamental mode at 47 GHz and operated at second harmonic of 94 GHz. Bias posts for diodes operate as LPF(low pass filter) and resonator. The fabricated waveguide VCO achieves an oscillation bandwidth of 760 MHz. Output power is from 12.61 to 15.26 dBm and phase noise is -101.13 dBc/Hz at 1 MHz offset frequency from the carrier.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.4
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• pp.670-676
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• 2008

There is a difficult plane letting a security threat to occur in Internet networks as VoIP service uses technology-based the Internet is inherent, and you protect without adjustment of the existing security solution or changes with real-time service characteristics. It is a voice to single networks The occurrence security threat that it is possible is inherent in IP networks that effort and cost to protect a data network only are complicated relatively as provide service integrated data. This paper about various response way fields to be able to prevent analysis regarding definition regarding VoIP spam and VoIP spam technology and VoIP spam.

• The Science & Technology
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• no.9 s.412
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• pp.12-16
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• 2003

AP통신은 평소 6000만 마일 떨어져 있는 지구와 화성 간의 거리가 우리나라 시간으로 8월 27일 오후 6시 51분에 3460만 마일까지 좁혀졌다고 밝혔다. 태양과 화성을 잇는 일직선상에 지구가 위치하는 행성직렬현상(Grand Alignment)은 대략 2.2년을 주기로 발생하며 '대접근'은 15년마다 다가온다. 하지만 이번 대접근은 특별하다. 네안데르탈인이 지구를 지배하던 BC 57617년 9월 12일 이래 약 6만년만에 찾아오는 대접근 중에서도 최대접근에 해당한다. 게다가 이들 두 행성은 오는 2287년 8월 28일에 가서야 다시 가까워지므로 살아있는 지구인이 이런 장관을 지켜볼 수 있는 것은 이번이 마지막 기회이다. 이를 계기로 미국 · 유럽 · 일본은 화성탐사에 나섰다. 그 현장을 소개한다.

• Bulletin of the Korean Chemical Society
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• v.30 no.12
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• pp.3117-3119
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• 2009

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.5C
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• pp.395-402
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• 2008

In this paper, an I/Q channel 12bits 40MS/s Pipeline Analog to Digital Converter that is able to apply to WLAN/WMAN system is proposed. The proposed ADC integrates DLL based duty-correction circuit which corrects the fluctuations in the duksty cycle caused by miniaturization of CMOS devices and faster operating speeds. It is designed as a 1% to 99% input clock duty cycle could be corrected to 50% output duty cycle. The prototype ADC is implemented in a $0.18{\mu}m$ CMOS n-well 1-poly 6-metal process and dissipates 184mW at 1.8V single supply The SNDR of the proposed 12bit ADC is 52dB and SFDR of 59dBc(@Fs=20MHz, Fin=1MHz) is measured.

• Journal of Navigation and Port Research
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• v.30 no.10 s.116
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• pp.847-853
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• 2006

In this paper, we designed VCO(voltage controlled oscillator} that is composed of a dielectric resonator and a varactor diode, and the PLDRO(phase locked dielectric resonator oscillator) that is combined with the sampling phase detector and loop filter. The results at 12.05 GHz show the output power is 13.54 dBm frequency tuning range approximately +/- 7.5 MHz, and power variation over the tuning range less than 0.2 dB, respectively. The phase noise which effects on bits error rate in digital communication is obtained with -114.5 dBc/Hz at 100 kHz offset from carrier, and The second harmonic suppression is less than -41.49 dBc. These measured results are found to be more improved than those of VCO without adopting PLL, and the phase noise and power variation performance characteristics show the better performances than those of conventional PLL.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.7 s.110
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• pp.694-705
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• 2006

In this paper, the linear active phased array antenna system operated in Ku DBS band was designed and experimented. The antenna system was composed of sixteen radiating active channels and Wilkinson power combiners with 16-channel inputs, a stabilizing DC bias and phase control board. Electrical beams of the antenna system can be formed by controling the phase-states of 3-bit digital phase shifter inside each active channel by virtue of the phase control board. The amplitude and phase deviations measured between active channels were less than ${\pm}0.8dB$ and ${\pm}15^{\circ}$, respectively, and the noise figure of each active channel was measured less than 1.2 dB in the operating band. The measured performances of the overall antenna system showed the antenna gain of more than 23.07 dBi and the sidelobe level of less than -11.17 dBc, and the bore-sight cross-polarization level of less than -12.75 dBc in the operating band. Also, by phase-controlling active channels, the beam scan patterns at $10^{\circ},\;20^{\circ},\;30^{\circ}$ were measured, and the losses caused by the corresponding beam scanning were 1.1 dB, 2.5 dB and 3.6 dB from the measurements, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.12
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• pp.1167-1172
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• 2013

This paper presents a X-band doppler radar with high conversion gain using a self-oscillating-mixer(SOM) that oscillation and frequency mixing is realized at the same time. To improve phase noise of the SOM oscillator, a ${\lambda}/2$ slotted square patch resonator(SSPR) was proposed, which shows high Q-factor of 175.4 and the 50 % reduced circuit area compared to the conventional resonator. To implement the low power system, low biasing voltage of 1.7 V was supplied. To enhance the conversion gain of the SOM, bias circuit is configured near the pinch-off region of transistor, and the conversion gain was optimized. The output power of the proposed SOM was -3.16 dBm at 10.65 GHz. A high conversion gain of 9.48 dB was obtained whereas DC Power consumption is relatively low about 7.65 mW. The phase noise is -90.91 dBc/Hz at 100 kHz offset. The figure-of-merit(FOM) of the proposed SOM was measured as -181.8 dBc/Hz, which is supplier to other SOMs by more than about 7 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.121-128
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• 2010

This paper presents a design of a 100 W high-efficiency power amplifier, whose operational frequency band expands from 30 to 512 MHz, using negative feedback network, push-pull structure, broadband RF choke, and transmission line transformer for balun configuration. The push-pull amplifier has been tuned for higher output power using a shunt capacitor as a matching component at its load especially for high-frequency region. The implemented power amplifier exhibited a very flat power gain of $18.34{\pm}0.9\;dB$ throughout the operating frequency band and very high power-added efficiency(PAE) of greater than 40% at an output power of 100 W. It also showed second- and third-harmonic distortion levels of below -34 dBc and -12 dBc, respectively, through the entire operating frequency band.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.3 s.333
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• pp.25-32
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• 2005

In this papers, we first, therefore, designed VCO(voltage controlled oscillator) that is composed of the dielectric resonator and the varactor diode, and then designed and fabricated PLDRO(phase locked dielectric resonator oscillator) that is combined with the sampling phase detector and loop filter. The measured results of the fabricated PLDRO at 12.05 [GHz] show the output power is 13.54 [dBm], frequency tuning range approximately +/- 7.5 [MHz], and Power variation over the tuning range less than 0.2 [dB], respectively. The phase noise which effects on bits error rate in digital communication is obtained with -114.5 [dBc/Hz] at 100 [KHz] offset from carrier, and The second harmonic suppression is less than -41.49 [dBc]. These measured results are found to be more improved than those of VCO without adopting PLL, and the phase noise and power variation performance characteristics show the better performances than those of conventional PLL.