• Journal of Satellite, Information and Communications
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• v.12 no.3
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• pp.80-85
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• 2017

In this paper, a mircrowave breakdown of X-band circular waveguide cavity filter, which occurred during ground test, was introduced, and electro-magnetic field simulation results to identify a root cause, and the analysis of possibility of its occurrence on orbit operation were presented. Filter modeling for simulation was conducted with a commercial tool (FEST3D), and electric fields inside the filter were monitored at the input of 1 W continuous wave. In our observation, strong electric field intensities were monitored on the tuning screws especially at the input of band-edge frequencies. The threshold power levels for the breakdown were also estimated and compared with the input power levels actually injected to the filter. From this estimation, we could figure out that the power exceeding the breakdown threshold was injected to the filter so that strong electric fields were generated and temperature increased high, and this became a root cause of the electrical short. Our further analysis showed that this kind of microwave breakdown is not likely to occur on orbit operation, and multipactor is expected not to occur at the input of band-edge frequencies. As a measure to prevent the microwave breakdown, we suggested to avoid the injection of band-edge frequencies and inject lower power levels to the filter.

• 한국ITS학회:학술대회논문집
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• 2004.11a
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• pp.323-327
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• 2004

• Journal of electromagnetic engineering and science
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• v.17 no.3
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• pp.147-152
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• 2017

This paper presents a frequency doubler operating at G-band that exceeds the maximum oscillation frequency ($f_{max}$) of the given transistor technology. A common-source transistor is biased on class-B to obtain sufficient output power at the second harmonic frequency. The input and output impedances are matched to achieve high output power and high return loss. The frequency doubler is fabricated in a commercial 150-nm GaAs pHEMT process and obtains a measured conversion gain of -5.5 dB and a saturated output power of -7.5 dBm at 184 GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.3
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• pp.333-340
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• 2015

In this paper, we propose a passive microwave sensor for detecting human body using microwave radiometer technologies. The proposed sensor detects human body by measuring the change of the received radiation power from fixed background object due to human body. A C-band microwave radiometer is designed and implemented. The received radiation power changes due to human body is measured by the C-band microwave radiometer, and the effectiveness of the proposed sensor is evaluated by the measurement result analysis.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.2
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• pp.276-279
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• 2015

This paper presents two 3-stage D-band stacked amplifiers developed in a $0.13-{\mu}m$ SiGe BiCMOS technology, employed to compare the conventional cascode topology and the common-base (CB)/CB stacked topology. AMP1 employs two cascode stages followed by a CB/CB stacked stage, while AMP2 is composed of three CB/CB stacked stages. AMP1 showed a 17.1 dB peak gain at 143.8 GHz and a saturation output power of -4.2 dBm, while AMP2 showed a 20.4 dB peak gain at 150.6 GHz and a saturation output power of -1.3 dBm. The respective power dissipation was 42.9 mW and 59.4 mW for the two amplifiers. The results show that CB/CB stacked topology is favored over cascode topology in terms of gain near 140 GHz.

• Proceedings of the Korean Society for Cognitive Science Conference
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• 2010.05a
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• pp.55-59
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• 2010

To examine iterocular interactions in normal subjects, we recorded EEG activity from channel O1 and O2 on 14 healthy subjects while checkerboard pattern reversals were presented to each eye with different interstimulus intervals (ISIs) ranging from 0 to 218 ms. When pattern reversals were presented asynchronously to each eye, P-1 activity evoked by each reversal was significantly suppressed compared to the activation evoked by synchronous reversals. Furthermore, when there was time delay between pattern reversals to each eye, theta (4-10 Hz) band power was also significantly decreased, whereas beta (10-30 Hz) band power was relatively preserved. Our results suggest that neural activity evoked by sustained but not yet reversed checkerboard from one eye might inhibit upcoming neural response evoked by reversed checkerboard from the other eye. Decreased P-1 activity might reflect such inhibitory interaction between two eyes. Also, decreased theta and preserved beta band power might reflect engagement of different neural circuit for binocular / monocular vision.

• ETRI Journal
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• v.33 no.6
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• pp.969-972
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• 2011

This letter presents a CMOS RF front-end operating in a subthreshold region for low-power Band-III mobile TV applications. The performance and feasibility of the RF front-end are verified by integrating with a low-IF RF tuner fabricated in a 0.13-${\mu}m$ CMOS technology. The RF front-end achieves the measured noise figure of 4.4 dB and a wide gain control range of 68.7 dB with a maximum gain of 54.7 dB. The power consumption of the RF front-end is 13.8 mW from a 1.2 V supply.

• ETRI Journal
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• v.44 no.4
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• pp.531-542
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• 2022

With the increasing demand for unlicensed spectrum, several regulators have been opening up the 6-GHz band for unlicensed use while ensuring compliance with the technical requirement to avoid harmful interference in the existing primary services (PSs). In this paper, we present two methodologies, a channel-based method and a frequency-based method, which are applicable to a frequency coordination system that calculates the permissible transmit power in the channels or frequencies available to a secondary service (SS). In addition, we have demonstrated that the available transmit power of an SS can be maximized by adjusting the power allocation of the assigned resource units under the condition that the channel of the SS is partially overlapped with that of the PS. Based on the analysis results, it is suggested that it would be better to utilize the two methods selectively according to the operating channel conditions of the PS and the SS.

• The Journal of Korean Physical Therapy
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• v.16 no.3
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• pp.152-160
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• 2004

The purpose of this study was to investigate the effect of elastic band based of PNF pattern on the U/E function in the spinal cord injury patient. 11 subjects with spinal cord injury participated in this study. They took elastic band excercise 5 times per week for 8 weeks. One time excercise spent 35minutes. The therapeutic effect was evaluated by Cybex 6000, BTE Work Simulator, how many seconds they needed to walk 100 meters. 11 cases were examined before, after 8 week, elastic band excercise. The results of this study are as follows; 1. Isokinetic power by Cybex 6000 : The elbow flexion, shoulder flexion and extension were significant difference between test-retest(p<.05). but elbow extension were not significant difference between test-retest. 2. BTE Work Simulator : Wheelchair Propulsion and Steering Torque were significant difference between test-retest(p<.05). 3. Wheelchair Propulsion velocity : There were significant difference between test-retest(p<.05). The findings suggest that SCI patients can improve their Isokinetic power on shoulder and elbow joint, wheelchair propulsion and Steering Torque by BTE Work Simulator, Wheelchair Propulsion velocity through elastic band based of PNF pattern.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.10 no.3
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• pp.368-377
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• 1999

In this paper, the wide-band CDMA transmitter for 2 GHz band is designed and implemented. The CC-OQPSK implemented as ASIC has better spectral and power efficiency than the conventional QPSK system because it has constant envelope characteristics. Good harmonics rejection characteristics and gain of 20 dB are shown on the intermediate frequency stage using double-conversion scheme. The output power of two-stage RF amplifier is +2l.14 dBm in 1.9 GHz band. It is confirmed that the electrical characteristics of the transmitter satisfy with required the specification of the wide-band CDMA transmitter for 2 GHz band.