• Journal of the Korean Institute of Telematics and Electronics A
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• v.31A no.1
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• pp.26-32
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• 1994

In this paper, using the newly developed GaAs Schottky beam-lead diode made by Marconi company, we have developed and evaluated the waveguide type single-ended mixer at Q-band. The various components of the mixer were separately designed and optimized using the Super-Compact software. These studies included the design of the step waveguide impedance transformer and the RF-choke filter, and the optimization of a high and low impedance for the RF-choke filter. Moreover, this RF-choke filter pattern included a section to reject the second harmonic frequency of the RF signal. Finally, this Q-band mixer with 1.4GHz/400MHz IF frequency exhibits an average conversion loss of 5.3 dB over 33-50GHz bandwidth.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.11a
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• pp.387-388
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• 2008

This paper presents the design approach and test results of the Q-band precision subminiature coaxial adaptor based on transmission line theory using multi-step impedance and air-holes to increase its cutoff frequency. In order to increase the frequency performance, the adaptor is designed with hooked structure, fixing step, multi-air-holes, and outer conductor. The return loss increments due to the hooked structure and multi air-holes are minimized to 2 dB and 1.5 dB, respectively. A VSWR(Voltage Standing Wave Ratio) of <1.2 is obtained from DC to 40 GHz, while guaranteeing the durability of the adaptor from room-temperature$(25^{\circ}C)$ to $120^{\circ}C$.

• Journal of Astronomy and Space Sciences
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• v.21 no.1
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• pp.29-38
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• 2004

A ultra low noise Q-band HEMT receiver for VLBI has been developed using a local oscillator with a very high phase stability. The performance of receiver was verified by comparison with receivers which were developed at the other countries. The receiver noise temperature shows 65 K in the frequency ragne from 42 ㎓ to 44 ㎓, less than 100 K from 39 ㎓ to 46 ㎓, respectively. A receiver noise temperature at SiO major line of 43㎓ which will be mainly observed by using this receiver has been optimized.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.4
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• pp.45-50
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• 2004

In this paper, we present the low voltage and high efficiency Q-band MIMIC oscillator using device-level power combined structure. The oscillator was successfully integrated by using 0.1 ${\mu}{\textrm}{m}$ GaAs PHEMTS and the CPW transmission line. We show that the highest efficiency is 19 % with an output power of 2.6 ㏈m at a frequency of 34.56 ㎓. The operating voltage of the oscillator is 2.2 V which is lower voltage than that of previously reported oscillators at Q-band. And the maximum output power of 6.7 ㏈m was obtained at a frequency of 34.56 ㎓.

• The Journal of Korean Academy of Orthopedic Manual Physical Therapy
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• v.27 no.3
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• pp.17-24
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• 2021

Background: The study aimed to examine changes in muscle activity by measuring the Q-angle and lower extremity activity when going down the stairs, after the application of either Mulligan taping or flossing bands to patients with chronic ankle instability. Methods: A total of 19 men with chronic ankle instability in their 20s and 30s participated in the study. Participants were randomly divided into two groups: the Mulligan taping group (n = 9) and the flossing band group (n=10). The Mulligan taping group had three sets of Mulligan joint operations repeated 10 times, after which the Mulligan tape was applied. The flossing band group either performed functional activities or exercised for 2 minutes after flossing band application. After the application of either Mulligan taping or flossing bands, changes in the Q-angle and lower limb muscular activity while going down the stairs were measured and compared. Results: In the Mulligan taping group, the Q-angle significantly decreased from 13.63° to 12.7° during the step down. Similarly, the Q-angle of the flossing band group significantly decreased from 15.95° to 15.48° (p<.05). There was no difference in lower limb muscle activity between the two groups when going down the stairs. The muscle activity of the tibialis anterior significantly increased from 34.12% to 40.2%, and the difference between the two groups were statistically significant (p<.05). Conclusions: The study found that the application of Mulligan taping and flossing bands to patients with chronic ankle instability decreased the Q-angle and lower limb muscle activity when going down the stairs.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.3
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• pp.1-6
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• 2008

A dual band I/Q modulator which converts baseband input signals to 2.4GHz or 5GHz RF output has been proposed. The dual band I/Q modulator for 2.4GHz and 5GHz wireless LAN applications consists of $90^{\circ}$ phase shifter and wideband mixer. The I/Q modulator showed 15dB conversion loss at 2.4GHz and 16dB conversion loss at 5GHz. The sideband suppression is about 15dBc at 2.4GHz and 16dBc at 5GHz. Measured data shows 8.5% EVM at 2.4GHz, and 10% EVM at 5GHz for QPSK with symbol rate of 11Mbps. A carrier rejection is about 40dBc at 2.4GHz/5GHz band, and the I/Q modulator satisfied the output wireless LAN spectrum mask with baseband input signal.

• The Bulletin of The Korean Astronomical Society
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• v.41 no.2
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• pp.32.2-32.2
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• 2016

We present the catalog of the KVN Calibrator Survey (KVNCS). This first part of the KVNCS is a single dish radio survey conducted at 22 (K band) and 43 GHz (Q band) simultaneously using the Korean VLBI Network (KVN) from 2009 to 2011. A total 2045 sources selected from the VLBA Calibrator Survey (VCS) with an extrapolated flux limit of 100 mJy at K band. The KVNCS contains 1533 sources in the K band with a flux limit of 70 mJy and 553 sources in the Q band with a flux limit of 120 mJy; it covers the whole sky down to -32. ${\circ}$ 5 in declination. Five hundred thirteen sources were detected in the K and Q bands, simultaneously; ~76% of them are flat-spectrum sources ($-0.5{\leq}{\alpha}{\leq}0.5$). From the flux-flux relationship, we anticipated that the most of the radiation of many of the sources comes from the compact components. Therefore, the sources listed in the KVNCS are strong candidates for high frequency VLBI calibrators.

• Journal of Ginseng Research
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• v.22 no.3
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• pp.168-172
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• 1998

Systematic electrophoretic analysis of alcohol-soluble proteins and salt-soluble proteins of 247 Panax ginseng (P.g) and Panax quinquefolium (P.q) germplasms seed was carried out on an improved lactate-polyacrylamide gel electrophoresis, a method with high resolving power, good reproducibility and stability. The electrophoregrams of proteins, according to their migration rate, were classified into four groups such as ${\alpha}$, ${\beta}$, ${\gamma}$ and $\omega$ for the alcohol-soluble proteins and three such as I, II and III for the salt-soluble ones. Panax ginseng or Panax quinquefolium had their own unique band pattern distinguishable from each other, regarding as their specific "fingerprint". In this study, 3 of 168 (1.8%) P.g germplasms and 1 of 79 (1.3%) P.q germplasms had their own unique band pattern, showing that P.g and P.q germplasms have poor genetic diversity in species. The band patterns of dry seed and stratified seed (embryo rate=60%) were basically the same. The band number of the F, hybrid of p.gx p.q was exactly equivalent to the number of the common bands plus the specific bands of the two parents, indicating that the difference of band patterns was a genetic trait con- trolled by the nuclear genes. The electrophoregram of F1 of P.g x P.q could be predicted by that of the two parents and the band pattern of the F1 hybrids could be demnonstrated by that of the mixed seed extract from the two parents.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.7
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• pp.1191-1198
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• 2001

MMIC low noise amplifiers for millimeter-wave application using 0.15 $\mu$m pHEMT have been presented in this paper. The design emphasis is on active device model and EM simulation. The deficiency of conventional device models is identified. A distributed device model has been adapted to circumvent the scaling problems and, thus, to predict small signal and noise parameters accurately. Two single-ended low noise amplifier are designed using distributed active device model for Q-band(40 ∼ 44 GHz) and V-band(58 ∼65 GHz) application. The Q-band amplifier achieved a average noise figure of 2.2 dB with 18.3 dB average gain. The V-band amplifier achieved a average noise figure of 2.9 dB with 14.7 dB average gain. The design technique and model employed provides good agreement between measured and predicted results. Compared with the published data, this work also represents state-of-the-art performance in terms of gain and noise figure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.533-534
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• 2008

This paper presents a multi-phase ring VCO for low-cost, low-power GPS receiver. In the RF band used in GPS, L1 band is now in commercial-use and L2,L5 are predicting to be commercial-use soon. Thus Wide band PLL and Cost-effective IC solutions are required for future multi-band GPS receiver that received three types band at once. A new PLL architecture for multi-band GPS application is proposed. Ring VCO is even smaller than LC-VCO and a good alternative for low-cost solution. Proposed multi-phase ring VCO offers wide frequency range covering L1, L2, and L5 band, 20% reduction of area, 23% reduction of PLL power and can generate I/Q without extra I/Q generator.