• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.18-26
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• 2015

In this paper, we studied the method for analyzing and estimating the parameters that induce I/Q imbalance in the repeater using direct conversion RF. In repeater, amplitude, phase, and filter mismatch are generated in the receiving-end which converts RF signal to baseband signal. And amplitude and phase mismatch are generated in the transmitting-end which converts baseband signal to RF signal. Accordingly, we modeled the parameters that cause I/Q imbalance in the structure of the repeater in order, and proposed a feedback test structure from the transmitting-end to the receiving-end for estimating the corresponding parameters. By comparing the test transmitting signal and received signal, it is possible to estimate the I/Q imbalance parameters which occurred from mixed components of real and imaginary part. And it was confirmed that I/Q imbalance phenomenon has been properly compensated with estimated parameters at the direct conversion RF repeater.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.6
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• pp.534-538
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• 2016

This paper discusses the characteristics and effects of dielectric inner-supports on discone antenna for broadband RF test chamber, and the verification has been performed by simulation. Several design parameters such as the thickness of the gap support, the position of the side support, and the thickness of the side support has been analyzed. The thickness of the gap support affected the reflection coefficient. An effect of the offset of the side support from the center was slight below 3 GHz and significant above 3 GHz. The thickness of the side support did not affect the reflection coefficient or the gain much. The performance of the fabricated discone antenna was in good agreement with the simulated results. This investigation of a dielectric support effects could be used to design a commercial discone antenna for broadband RF test chamber, focusing on electrical performance and mechanical stability.

• Journal of Ginseng Research
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• v.22 no.1
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• pp.43-50
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• 1998

We demonstrated in previous study that protopanaxadiol and protopanxatriol saponins show antinociceptive activity in acetic acid induced writhing test and in the second phase (11-40 min) of formalin test but not tail-flick test. To identify further which ginsenoside has antinociceptive activity among various ginseng saponins, we have investigated antinociceptive effects of several ginsenosides using writhing and formalin test. Ginsenoside Rc, Rd, Re, and Rf induced antinociception in writhing test. These four ginsenosides also induced antinociception in the second phase of formalin (11-40 min) test but these ginsenosides showed a slight antinociception in the first phase (010 min) of formalin test except ginsenoside Rf. The antinociceptive effects induced by the ginsenosides were dose dependent and were not blocked by an opioid receptor antagonist, naloxone. The order of antinociceptive potency was Rd > Rc > Re > Rf in the formalin test. However, these ginsenosides did not show any significant analgesic effects in a tail-flick test. These results suggest that ginsenosides such as Rc, Rd, Re, and Rf inhibit tonic pain rather than acute pain induced by noxious heat. These results also indicate that the antinociceptive activity. Induced by ginsenosides may be one of the actions for pharmacological effects of Panax ginseng.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.46 no.1
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• pp.49-54
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• 2009

This paper proposes a new approach to provide RF communication channel and electric power transmission to overcome the weakness of conventional tests, which may cause several problems. When an RF communication device is used to communicate between launch vehicle and launch complex in stead of using harness umbilical, it may draw the simplicity of ground test equipments, cost-saving, and the reduction of test time. In addition, if an RF power transmission device is adopted to supply on-board power of launch vehicle, it can replace expensive on-board batteries, which may be degraded easily by the repeated charging and discharging processes.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.8
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• pp.36-46
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• 2010

In multi-GHz RF ICs and high-speed digital interfaces, ESD protection devices introduce considerable parasitic capacitance and resistance to inputs and outputs, thereby degrading the RF performance, such as input/output matching, gain, and noise figure. In this paper, the impact of ESD protection devices on the performance of RF ICs is investigated and design methodologies to minimize this impact are discussed. With RF and ESD test results, the 'RF/ESD co-design' method is discussed and compared to the conventional RF ESD protection method which focuses on minimizing the device size.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.2
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• pp.39-47
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• 2003

Cr thin films were deposited on photosensitive polyimide substrates by RF bias sputtering and DC sputtering and the interfaces between Cr thin film and polyimide were observed using TEM. When the polyimide surface was in-situ RF plasma cleaned at the RF power density of 0.13-2.12 $W/cm^2$, increasing of RF power density changed the morphology of polyimide surfaces from round dig to sharp shape, and surface roughness increased by anisotropic etching. The intermixed layer-like interfaces between Cr and polyimide were observed in the RF bias sputtered specimens. This interface seems to be formed due to the RF cleaning effect; the polyimide surface was RF plasma cleaned while RF power was increased to the setting point before Cr deposition.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.9
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• pp.2164-2170
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• 2010

Digital Radio Frequency Memory, ( as DRFM ), is a device with the ability to restore output to the input RF signal in the required time after storing the incoming RF signals. Therefore DRFM is widely used in Jammer, EW Simulator, Target Echo Generator, and so on. This paper proposes its hardware implementation composed with the high frequency part and the digital processing part consisting of RF input/output module and local oscillator module. It is also proposed the replicated signal generation method which is consisted of the Analog-Digital conversion in the form of pulsed RF signal quantization, and FPGA to save and produce the playback signal, and RF signals to produce a Digital-Analog Conversion in the digital processing unit. This proposed scheme applied to test board and confirmed the validity of the proposed scheme through the test results obtained by the simulated input signals.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.454-459
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• 2007

In this work, micro-scale, high-performance solenoid-type RF chip inductors utilizing amorphous $Al_2O_3$ core material were investigated. The size of the chip inductors was $0.86{\times}0.46{\times}0.45mm^3$ and copper(Cu) wire with $27{\mu}m$ diameter was used as the coil. High frequency characteristics of the inductance(L), quality factor(Q), impedance(Z), and equivalent circuit parameters of the RE chip inductors were measured and analyzed using an RF impedance/material analyzer(HP4291B with HP16193A test fixture). It was observed that the RF chip inductors with the number of turns of 9 to 12 have the inductance of 21 to 34nH and exhibit the self-resonant frequency(SRF) of 5.7 to 3.7GHz. The SRF of inductors decreases with increasing the inductance and inductors have the quality factor of 38 to 49 in the frequency range of 900MHz to 1,7GHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.6
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• pp.591-596
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• 2016

This paper presents a study on the subject for the design and implementation of high-speed frequency hopping RF transceiver used for tactical communications systems. Jump the transmission / reception frequency of the L-band to hop tens per second is possible by maximizing the immunity to interference, and is applicable to communication systems having a charging rotation function. To high-speed frequency hopping it is necessary to apply the necessary fast frequency hopping scheme DDS Driven PLL added. In this paper, the RF transceiver design and simulation analysis capabilities with fast frequency tactical communication systems, were implemented after the main test for functionality and performance. Was demonstrated hop high-speed jump tens per second through a test, the main transmission output, were measured RF key performance, such as received noise figure, by using the VSG and VSA generates a ${\pi}/4$ DQPSK modulated signal constellation and by EVM measurement that there is no problem in applying the communications system described above was pre-validated.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.5
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• pp.409-416
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• 2017

In order that multiple wideband RF transmitters which have mission to deliver essential information to aircraft operate at the same time, RF transmitter has a variable sub-carrier frequency to modulate the signal. In case of exposure to weak environment, Wide-band RF transmitter is designed to check component of transmitter that includes antenna BIT to increase system reliability. Normally, Antenna BIT measure the reflection RF power of antenna to check system condition. However, Antenna BIT has a difference that depends on testing frequency to use the long RF cable which is located between the power amp and the antenna. The periodic phenomenon of the reflected antenna power are theoretically explained about dependence on the RF cable length. Based on presented result, suggested measurement methods is effectively able to be applied to diagnosis system condition.