• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.4A
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• pp.586-591
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• 2000

In this paper, a PLHRO(Phase Locked Hair-pin Resonator Oscillator) for K-band is designed with the feedback property of PLL(Phase Locked Loop) using a new tuning mechanism. The proposed PLHRO generates the output power of -0.6 dBm at 24.42 GHz, and has the phase noise of -86.6 dBc/Hz at 100 KHz and -76.5 dBc/Hz at 10KHz offset from carrier frequency, and has suppression characteristics of -23 dBc and spurious noise of -65 dBc. Buffered 24.42 GHz PLHRO generates the output power of 5.6 dBm at 24.42 GHz and has the of a phase noise of -77.34 dBc/Hz at 100 KHz and -72 dBc/Hz at 100 KHz offset from carrier frequency.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.8
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• pp.65-73
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• 2007

This paper presents a low power CMOS continuous-time $\Sigma\Delta$ (sigma-delta) modulator for UMTS receivers. The loop filter of the continuous-time $\Sigma\Delta$ modulator consists of an active-RC filter which performs high linearity characteristics and has a simple tuning circuit for low power operating system The architecture of this modulator is the $3^{rd}-order$ 4-bit single loop configuration with a 24 of OSR (Oversampling Ratio) to increase the power efficiency. The modulator includes a half delay feedback path to compensate the excess loop delay. The experimental results of the modulator are 71dB, 65dB and 74dB of the peak SNR, peak SMR and dynamic range, respectively. The continuous-time $\Sigma\Delta$ modulator is fabricated in a 0.18-um 1P4M CMOS standard process and dissipates 15mW for a single supply voltage of 1.8V.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.11
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• pp.1104-1111
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• 2008

The supersonic advanced trainer based on digital flight-by-wire flight control system uses aircraft flight information such as altitude, calibrated airspeed and angle of attack to calculate flight control law, and this information is measured by IMFP(Integrated Multi-Function Probe) equipment. The information has triplex structure using three IMFP sensors. Final value of informations is selected by mid-value selection logic to have more flight data reliability. As the result of supersonic flight test, pitch oscillation is occurred due to IMFP noise when altitude hold autopilot mode is engaged. This tendency may affect stability and handling quality of an aircraft during autopilot mode. This paper addresses autopilot control law design to remove pitch oscillation and these control laws are verified by non-real time simulation and flight test. Also, pitch response characteristics of pitch attitude hold autopilot mode is improved by upgrading the control law structure and feedback gain tuning during bank turn.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.1
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• pp.23-30
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• 2007

We observed the NaCl concentration of solutions using a near-field microwave microprobe(NFMM). Instead of the usual technique, we take advantage of the noncontact evaluation capabilities of a NFMM. A NFMM with a high Q dielectric resonator allows observation of small variations of the permittivity due to changes in the NaCl concentration. The changes of NaCl concentration due to a change of permittivity of the NaCl solution were investigated by measuring the microwave reflection coefficient $S_{11}$ of the resonator. The NaCl sensor consisted of a dielectric resonator coupled to a probe tip at an operating frequency of about f=4 GHz. The change of the NaCl concentration is directly related to the change of the reflection coefficient due to a near field electromagnetic interaction between the probe tip and the NaCl solution. In order to determine the probe selectivity, we measured a mixture solution of NaCl and glucose.

• Journal of the Korean Vacuum Society
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• v.15 no.4
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• pp.331-337
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• 2006

Cavity-type beam position monitors were developed in collaboration with KEK to use for the future accelerators such as international linear collider (ILC) or x-ray free electron laser (XFEL) in PAL. BPM components such as BPM cavity, beam tubes, waveguides and feedthroughs were assembled by brazing at the same time to reduce mechanical errors during the fabrication. There are four screwed pins around outer rim of the cavity for the tuning of cavity frequency and x-y isolation. The resonance frequency of BPM is 6.422 GHz, the inner diameter of cavity is 53.822 mm, and the range of mechanical adjusting is $+ / - 250{\mu}m$. The x-y isolation was measured better than -40 dB after tuned. Test results of signal forms, x-y isolations, sensitivities are satisfied within requirements for the KEK ATF2 beam line.