• Journal of Digital Contents Society
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• v.17 no.3
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• pp.173-180
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• 2016

In this paper, a design of transceiver module for real-time wire and wireless robust integrated security system to solve the problem of conventional security system and its transceiver module is proposed. The presented robust integrated security system is designed with RF control unit and wireless transceiver module. A RF controller in transceiver module works as a low-power RF transceiver system. It is designed to use specific bandwidth stored in registers and manipulate RF power of transceiver by accessing the random values of registers. Operation algorithm for RF transceiver module is also presented. The designed transceiver module and the operation algorithm are implemented and verified by experiments.

• Journal of The Korean Society of Integrative Medicine
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• v.11 no.2
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• pp.69-76
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• 2023

Purpose : This study aimed to compare lung capacity measures (forced vital capacity; FVC, forced expiratory volume at 1 second; FEV1, and FEV1/FVC) and the activities of rectus femoris (RF) and gastrocnemius (GCM) muscles between young adults prescribed aerobic exercise combined with lower limb strength exercise (complex exercise) and those prescribed only aerobic exercise. Methods : We randomly divided 22 young adults into 2 groups: the complex exercise group that combined the leg strengthening and aerobic exercises (n = 11) and the aerobic-exercise-only group (n=11). Before the intervention, the FVC, FEV1, and FEV1/FVC values and the activities of RF and GCM muscles were measured. Measurements were in triplicates, and the average of the 3 measurements was used. The complex exercise group performed the treadmill exercise followed by squats and lunges, and the group performed only the treadmill exercise. Both groups were allocated the same time. Both groups performed the assigned exercise thrice a week for 3 weeks. After the intervention, the FVC, FEV1, and FEV1/FVC values and the activities of RF and GCM muscles were measured again. Results : The FVC and FEV1 values increased significantly in both groups after the intervention (p<.05). RF activity increased significantly after the intervention in the complex exercise group (p<.05), and the magnitude of change in RF activity after the intervention was significantly higher in the complex exercise group than in the aerobic-exercise-only group (p<.05). GCM activity also significantly increased after the intervention in both groups (p<.05). Conclusion : On the basis of our results, we recommend combining leg strengthening and aerobic exercise to improve leg muscle activity along with lung function.

• Journal of Environmental Science International
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• v.32 no.8
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• pp.521-531
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• 2023

This study analyzed the impact of recirculation on high-concentration PM_2.5 in the coastal area. Through the analysis of observational data, it was observed that the development of sea breeze led to an increase in PM_2.5 and SO₄^2- concentrations. Hysplit backward trajectory analysis confirmed the occurrence of air mass recirculation. Results from WRF and CMAQ numerical simulations indicated that pollutants transported from land to sea during the night were re-transported to the land by daytime sea breeze, leading to high-concentration PM_2.5 in Busan. To quantitatively investigate the recirculation a recirculation factor (RF) was calculated, showing an increase in RF values during high-concentration PM_2.5 episodes. However, the RF values varied slightly depending on the time resolution of meteorological data used for the calculations. This variation was attributed to the terrain characteristics at observation sites. Additionally, during long-range transported days leading to nationwide high-concentration PM_2.5 events, synoptic-scale circulation dominated, resulting in weaker correlation between PM_2.5 concentration and RF values. This study enhances the understanding of the influence of recirculation on air pollution. However, it is important to consider the impact of temporal resolution and terrain characteristics when using RF for evaluating recirculation during episodes of air pollution.

• Investigative Magnetic Resonance Imaging
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• v.13 no.2
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• pp.171-176
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• 2009

Purpose : To investigate the effect of coating material in RF coil, which is one of main parts in MRI machine, on the Q-factor and SNR(signal-to-noise ratio) in MR images. Materials and Methods : RF coils with inner diameter of 1.7 mm were made by using copper wires coated with polyester, polyurethane, polyimide, polyamideimide, and polyester-imide, and by using copper wires in which coating materials had been removed. Q-factors of the RF coils were measured by network analyzer, and SNR values in the spin-echo MR images obtained by 600 MHz (14.1 T, Bruker DMX600) micro-imaging system for the coated and uncoated cases. Results : The measured SNRs were almost same for the RF coils with coat-removed copper wires, however SNRs and Q-factors were different for the coated cases depending on the coating material. They were maximized in the polyurethane-coated case in which the SNR was > 30% greater than polyester-coated case. Conclusion : We made solenoid-type RF coils which were easily used for MR micro-imaging in Bruker MRI probe. There was a significant coating-material dependence in the measured Q values and SNRs for the home-made RF coils. The study demonstrated that the choice of coating material of RF coil may be a critical factor in the MRI sensitivity based on SNR value.

• Journal of the Semiconductor & Display Technology
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• v.19 no.3
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• pp.43-48
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• 2020

The demand for stable plasma has been on the rise because of the increased delivery power amount in the chamber for improving productivity, and fast and accurate plasma impedance matching become a crucial performance measure for radio frequency (RF) power system in semiconductor manufacturing equipment. In this paper, the overall impedance matching was understood, and voltage and current values were extracted with voltage - current (VI) probe to measure plasma impedance in real-time. Actual matching data were analyzed to derive calibration coefficient for V and I measurements to understand the characteristics of VI probe, and we demonstrated the tendency of RF impedance matching according to changes in load impedance. This preliminary empirical research can contribute to fast RF matching as well as advanced equipment control for the next level of detailed investigation on embedded system based-RF matching controller.

• Progress in Superconductivity
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• v.11 no.2
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• pp.100-105
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• 2010

Reel-to-reel deposition of $Y_2O_3$ has been performed on Ni-5%W metal substrates using the RF-sputtering method. The epitaxial orientation of $Y_2O_3$ buffer layers to the base bi-axially textured substrate was well identified using ${\theta}-2{\theta}$, out-of-plane ($\omega$), and in-plane ($\phi$) scans in X-ray diffraction analysis. The optimization of $Y_2O_3$ seed layers in reel-to-reel fashion were investigated varying the deposition temperature, sputtering power, and pressure for its significant roles for the following buffer stacks and superconducting layers. $Y_2O_3$ were all grown epitaxially on bi-axially textured metal substrates at 380 watts and 5 mTorr in the temperature range of $600-740^{\circ}C$ with higher $Y_2O_3$ (400) intensities at ${\sim}710^{\circ}C$. It was found that the $\Delta\omega$ values were $1-2^{\circ}$ lower but the $\Delta\phi$ values were above $1^{\circ}$ higher than that of Ni-W substrates. As the sputtering power increased from 340 to 380 watts, $\Delta\omega$ and $\Delta\phi$ values showed decreased tendency. Even in the small window of deposition pressure of 3-7 mTorr, the $Y_2O_3$ (400) intensities increased and $\Delta\omega$ and $\Delta\phi$ values were reduced as sputtering pressure increased.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.1004-1007
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• 2005

This paper presents a programmable RF BIST (Built-in Self-Test) circuit for low noise amplifiers. We have developed a new on-chip RF BIST circuit that measures RF parameters of low noise amplifier (LNA) using only DC measurements. The BIST circuit contains test amplifier with programmable capacitor banks and RF peak detectors. The test circuit utilizes output DC voltage measurements and these measured values are translated into the LNA specifications such as input impedance and gain using the mathematical equations. Our on-chip BIST can be self programmed for 1.8GHz, 2.4GHz and 5.25GHz LNA for GSM, Bluetooth and IEEE802.11g standards.

• Journal of Aerospace System Engineering
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• v.16 no.2
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• pp.39-48
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• 2022

The purpose of this paper was to study how to improve the occurrence of abnormal altitude values of radio altimeter, due to RF interference signals during the flight of aircraft. In flight missions, since it performs a roll-out after several high maneuvers, accurate altitude must be displayed to effectively perform flight missions. Thus, a root cause analysis and trouble shooting were performed for the display of abnormal altitude values of radar altimeters, and a method of reducing RF interference signals by installing an attenuator was examined. Additionally, the verification results for the improvements are also described.

• ETRI Journal
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• v.25 no.2
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• pp.65-72
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• 2003

To achieve cost and size reductions, we developed a low cost manufacturing technology for RF substrates and a high performance passive process technology for RF integrated passive devices (IPDs). The fabricated substrate is a conventional 6" Si wafer with a 25${\mu}m$ thick $SiO_2$ surface. This substrate showed a very good insertion loss of 0.03 dB/mm at 4 GHz, including the conductive metal loss, with a 50 ${\Omega}$ coplanar transmission line (W=50${\mu}m$, G=20${\mu}m$). Using benzo cyclo butene (BCB) interlayers and a 10 ${\mu}m$ Cu plating process, we made high Q rectangular and circular spiral inductors on Si that had record maximum quality factors of more than 100. The fabricated inductor library showed a maximum quality factor range of 30-120, depending on geometrical parameters and inductance values of 0.35-35 nH. We also fabricated small RF IPDs on a thick oxide Si substrate for use in handheld phone applications, such as antenna switch modules or front end modules, and high-speed wireless LAN applications. The chip sizes of the wafer-level-packaged RF IPDs and wire-bondable RF IPDs were 1.0-1.5$mm^2$ and 0.8-1.0$mm^2$, respectively. They showed very good insertion loss and RF performances. These substrate and passive process technologies will be widely utilized in hand-held RF modules and systems requiring low cost solutions and strict volumetric efficiencies.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.339-342
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• 1997

The optical properties of WO$_3$thin films deposited by RF magnetron reactive sputtering were studied. The substrate was an ITO(indium-tin-oxide) glass(100$\Omega$/ ). The optical properties are examined by different deposition conditions. RF power, substrate temperature, $O_2$concentraction. Ar flow rate, working pressure and thickness are 40~60W, 25~30$0^{\circ}C$, 10%, 54~72sccm, 5~20m7orr and 1200~2400$\AA$, respectively. All these films were colorless, light yellow and found to be amorphous in structure by X-ray diffraction analysis. When RF power, substrate temperature, $O_2$concentraction, Ar flow rate, working pressure and thickness are 40W, $25^{\circ}C$, 10%, 72sccm, 20mTorr and 2400$\AA$, respectively the values of transmittance of the WO$_3$thin films in visible region are about 80%.