• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.6
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• pp.726-732
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• 2019

In this study, we proposed an asymmetric differential inductor to improve the linearity of differential power amplifiers. Considering the phase error between differential signals of the differential amplifier, the location of the center tap of the differential inductor was modified to minimize the error. As a result, the center tap was positioned asymmetrically inside the differential inductor. With the asymmetric differential inductor, the AM-to-AM and AM-to-PM distortions of the amplifier were suppressed. To confirm the feasibility of the inductor, we designed a 2.4 GHz differential CMOS PA for IEEE 802.11n WLAN applications with a 64-quadrature amplitude modulation (QAM), 9.6 dB peak-to-average power ratio (PAPR), and a bandwidth of 20 MHz. The designed power amplifier was fabricated using the 180-nm RF CMOS process. The measured maximum linear output power was 17 dBm, whereas EVM was 5%.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.66-69
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• 2016

In this paper, we suggests a Ka-band LNB considering next-generation UHD satellite TVRO. Since Ka-band has grater attenuation than Ku-band in atmosphere, we designed the low-noise down-converter to improve receiving sensitivity and to extend a dynamic range of receiver. It aims to compensate a quality of ultra high definition transmission signal for rainfall. The low-noise block diagram consists of a three-staged amplifier (LNA), band-pass filter for deleting image (BPF), mixer and IF when considering nonlinear characteristics in the receiver RF front end module. Also, we showed a LNB through optimization processes affecting dynamic range directly in receiver FEM. Asa resuly of experiment, the gain of low-noise down-converter show between 58.5dB and 60.7dB, the noise figure has a high characteristic as 1.38dB. Finally, the phase noise of local oscillator is -63.10dBc at 100MHz offset frequency.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.4
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• pp.379-385
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• 2021

In order to synchronize a remote system time to the reference time like Coordinated Universal Time (UTC), it is required to compare the time difference between the two clocks. GNSS Precise Point Positioning (PPP) is one of the most general geodetic positioning methods and can be used for time and frequency transfer applications which require more precise time comparison performance than GNSS code. However, the PPP technique has a main drawback of day-boundary discontinuity which comes from the PPP model that the code measurements are applied to resolve the floating carrier-phase ambiguities. The Integer PPP (IPPP) technique is one of the methods which has been studied to compensate the day-boundary discontinuities exited in the conventional PPP. In this paper, we investigate the time and frequency capabilities of PPP and IPPP by using the measurement data obtained from two time transfer receivers which are closely located and using common reference 1 Pulse Per Second (PPS) and RF signals. From the experiment, it is investigated that the IPPP method can effectively compensate the day-boundary discontinuities without producing frequency offset. However, the PPP method can generating frequency offset which can severely degrade the time comparison performance with long-term period data.

• Herbal Formula Science
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• v.30 no.4
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• pp.269-280
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• 2022

Objectives : In this study, it was investigated the effects of solid-phase fermentation extraction with Phellinus linteus of discarded Schisandra chinensis extract (PS) and its action mechanism on dexamethasone-induced muscle atrophy in mice. Methods : In mice, muscle atrophy model was induced by dexamethasone (5 mg/kg, I.p) once daily for 2 weeks and with PS extract administration (100 and 300 mg/kg, p.o.) as treatment groups. The changes in body weights, grip strength, Treadmill test, muscle weights, and the expression of atrophy-related genes were measured in muscle atrophy mice. The histological changes of gastrocnemius tissues were also observed by H&E staining with measurement of myofiber size. Results : The administration of PS extract increased significantly body weights, grip strength, treadmill test and muscle weights in muscle atrophy mice. PS extract administration increased significantly the area of myofibers and inhibited structural damages of muscle and increased significantly the expression of myogenin and decreased significantly the expression of MuRF1, Atrogin1 and phosphorylation of AMPK and PGC1α in muscle tissues of muscle atrophy mice. Conclusions : These results indicate that PS extract has a improvement effects on muscle atrophy with stimulation of myogenic differentiation and inhibition of mRNA degradation that could be related with the activation of AMPK and PGC1α signaling pathways in muscle. This suggests that PS extract can apply to treat muscle atrophy in clinics.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.21-26
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• 2024

Design and fabrication method of W-band 12-way radial power combiner is proposed in this paper. The proposed structure is used with TE₁₀ to TEM mode converter, which is realized using 2-step impedance transformer. The pin structure for mode converter is well bonded to the housing so that environment conditions such as vibration or shock are not affected. Proposed W-band power combiner has less than 0.7 dB insertion loss and more than 13 dB return loss from 88 GHz to 98 GHz. The measured output isolations between each other are greater than 7.5 dB from 82 to 100 GHz and phase differences are less than 10 degree from 88 to 96 GHz. Proposed power combiner is expected compact radar and various applications requiring for high power and stable environment conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.251-252
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• 2012

Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low Water Vapor Transition Rate (WVTR) of $1{\times}10^{-6}g/m^2$/day. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2$/day) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study, we developed an $Al_2O_3$ nano-crystal structure single gas barrier layer using a Neutral Beam Assisted Sputtering (NBAS) process. The NBAS system is based on the conventional RF magnetron sputtering and neutral beam source. The neutral beam source consists of an electron cyclotron Resonance (ECR) plasma source and metal reflector. The Ar+ ions in the ECR plasma are accelerated in the plasma sheath between the plasma and reflector, which are then neutralized by Auger neutralization. The neutral beam energies were possible to estimate indirectly through previous experiments and binary collision model. The accelerating potential is the sum of the plasma potential and reflector bias. In previous experiments, while adjusting the reflector bias, changes in the plasma density and the plasma potential were not observed. The neutral beam energy is controlled by the metal reflector bias. The NBAS process can continuously change crystalline structures from an amorphous phase to nano-crystal phase of various grain sizes within a single inorganic thin film. These NBAS process effects can lead to the formation of a nano-crystal structure barrier layer which effectively limits gas diffusion through the pathways between grain boundaries. Our results verify the nano-crystal structure of the NBAS processed $Al_2O_3$ single gas barrier layer through dielectric constant measurement, break down field measurement, and TEM analysis. Finally, the WVTR of $Al_2O_3$ nano-crystal structure single gas barrier layer was measured to be under $5{\times}10^{-6}g/m^2$/day therefore we can confirm that NBAS processed $Al_2O_3$ nano-crystal structure single gas barrier layer is suitable for OLED application.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.157-157
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• 2015

Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low water vapor transition rate (WVTR) of $1{\times}10^{-6}g/m^2day$. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2day$) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study NBAS process was introduced to deposit enhanced film density single gas barrier layer with a low WVTR. Fig. 1. shows a schematic illustration of the NBAS apparatus. The NBAS process was used for the $Al_2O_3$ nano-crystal structure films deposition, as shown in Fig. 1. The NBAS system is based on the conventional RF magnetron sputtering and it has the electron cyclotron resonance (ECR) plasma source and metal reflector. $Ar^+$ ion in the ECR plasma can be accelerated into the plasma sheath between the plasma and metal reflector, which are then neutralized mainly by Auger neutralization. The neutral beam energy is controlled by the metal reflector bias. The controllable neutral beam energy can continuously change crystalline structures from an amorphous phase to nanocrystal phase of various grain sizes. The $Al_2O_3$ films can be high film density by controllable Auger neutral beam energy. we developed $Al_2O_3$ high dense barrier layer using NBAS process. We can verified that NBAS process effect can lead to formation of high density nano-crystal structure barrier layer. As a result, Fig. 2. shows that the NBAS processed $Al_2O_3$ high dense barrier layer shows excellent WVTR property as a under $2{\times}10^{-5}g/m^2day$ in the single barrier layer of 100nm thickness. Therefore, the NBAS processed $Al_2O_3$ high dense barrier layer is very suitable in the high efficiency OLED application.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.6
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• pp.436-441
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• 1998

$Pt/SrTiO_3/Pb_x(Zr_{0.52}, Ti_{0.48})O_3/SrTiO_3/Si$ structure was prepared by rf-magnetron sputtering method for use in nondestructive read out ferroelectric RAM(NDRO-FEAM). PBx(Zr_{0.52}Ti_{0.48})O_3}$(PZT) and $SrTiO_3$(STO) films were deposited respectively at the temperatures of $300^{\circ}C and 500^{\circ}C$on p-Si(100) substrate. The role of the STO film as a buffer layer between the PZT film and the Si substrate was studied using X-ray diffraction (XRD), Auger electron spectroscopy (ASE), and scanning electron microscope(SEM). Structural analysis on the interfaces was carried out using a cross sectional transmission electron microscope(TEM). For PZT/Si structure, mostly Pb deficient pyrochlore phase was formed due to the serious diffusion of Pb into the Si substrate. On the other hand, for STO/PZT/STO/Si structure, the PZT film had perovskite phase and larger grain size with a little Pb interdiffusion. the interfaces of the PZT and the STO film, of the STO film and the interface layer and $SiO_2$, and of the $SiO_2$ and the Si substate had a good flatness. Across sectional TEM image showed the existence of an amorphous layer and $SiO_2$ with 7nm thickness between the STO film and the Si substrate. The electrical properties of MIFIS structure was characterized by C-V and I-V measurements. By 1MHz C-V characteristics Pt/STO(25nm)/PZT(160nm)/STO(25nm)/Si structure, memory window was about 1.2 V for and applied voltage of 5 V. Memory window increased by increasing the applied voltage and maximum voltage of memory window was 2 V for V applied. Memory window decreased by decreasing PZT film thickness to 110nm. Typical leakage current was abour $10{-8}$ A/cm for an applied voltage of 5 V.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.25-31
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• 2008

Cp-Ti and Ti-6Al-4V alloys commonly used dental implant materials, particularly for orthopaedic and osteosynthesis because of its suitable mechanical properties and excellent biocompatibility. This alloys have excellent corrosion behavior in the clinical environment. The first factor to decide the success of dental implantation is sufficient osseointegration and high corrosion resistance between on implant fixture and its surrounding bone tissue. In this study, in order to increase corrosion resistance and biocompatibility of Cp-Ti and Ti-6Al-4V alloy that surface of manufactured alloy was coated with TiN by RF-magnetron sputtering method. The electrochemical behavior of TiN coated Cp-Ti and Ti-6Al-4V alloy were investigated using potentiodynamic (EG&G Co, PARSTAT 2273. USA) and potentiostatic test (250mV) in 0.9% NaCl solution at 36.5 $\pm$ 1$^{\circ}C$. These results are as follows : 1. From the microstructure analysis, Cp-Ti showed the acicular structure of $\alpha$-phase and Ti-6Al-4V showed the micro-acicular structure of ${\alpha}+{\beta}$ phase. 2. From the potentiodynamic test, Ecorr value of Cp-Ti and Ti-6Al-4V alloys showed -702.48mV and -319.87mV, respectively. Ti-6Al-4V alloy value was higher than Cp-Ti alloy. 3. From the analysis of TiN and coated layer, TIN coated surface showed columnar structure with 800 nm thickness. 4. The corrosion resistance of TiN coated Cp-Ti and Ti-6Al-4V alloys were higher than those of the non-coated Ti alloys in 0.9% NaCl solution from potentiodynamic test, indicating better protective effect. 5. The passivation current density of TiN coated Cp-Ti and Ti-6Al-4V alloys were smaller than that of the noncoated implant fixture in 0.9% NaCl solution, indicating the good protective effect resulting from more compact and homogeneous layer formation.

• Korean Journal of Food Science and Technology
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• v.13 no.1
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• pp.57-66
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• 1981

An effective method for isolation of the major components of ginseng saponin such as $ginsenoside-Rb_{1},\;-Rb_2,$ -Rc, -Rd, -Re and $-Rg_1$, and the minor components such as ginsenoside-Rf, $-Rg_2,\;and-Rh_1$, was developed and reported in previous papers (J. Korean Agr. Chem. Soc., 23(4), 199 and 206(1980) The conditions and procedures used for isolation and identification for ginsenosides described in the previous papers were not sufficient enough for clean separation of minor components, $ginsenoside-Rh_1,\;and-Rh_2$. In this work, modifications in extraction method and in mobile phase for HPLC were attempted. It was found that application of ethyl acetate extraction at $60^{\circ}C$ for 3 hr on crude saponin resulted in a removal of diol group saponin from crude saponin which made it possible for using higher portion of acetonitrile in mobile phase. The mixed solvents of acetonitrile : water (92 : 8 and 94 : 6) gave excellent resolution of $ginsenoside-Rh_1\;and\;-Rh_2$.