• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.12
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• pp.691-698
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• 2014

An L-band single side band(SSB) mixer with CMOS switches and a C-band quadrature voltage-controlled oscillator(QVCO) have been developed using the TowerJazz 0.18-um RFCMOS process. The SSB mixer exhibits a conversion gain of 6.6 ~ 7.5 dB with a 70-dBc image rejection ratio and 65-dBc port isolation. The oscillation frequency range of the QVCO is 6.2 ~ 6.7 GHz with an output power of 4~6 dBm. For measurement, 1.8 V supply voltage is used while drawing 36 mA for the mixer and 23 mA for the QVCO.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.10
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• pp.1240-1247
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• 2019

In this paper, we designed a four-band antenna that can be applied to WLAN and WiMAX systems by designing a microstrip feeding structure, four branch lines and a slit on the ground plane. The proposed antenna is designed with a size of 16.0 mm (W1) × 48.0 mm (L8) on a dielectric substrate of 18.0 mm (W) × 50.0 mm (L) × 1.0 mm(h). and a slit of 2.9 mm (W7) × 4.0 mm (L7) is inserted into the ground plane of 18.0 mm (W) × 18.7 mm (L6). Based on -10 dB production and measurement results, it obtained 60.8 MHz (8,730~9,338 MHz), 310 MHz (2.33~2.64 GHz) in the 2.4 GHz band, 420MHz (3.39~3.81 GHz) in the 3.4 GHz band, and 2,070 MHz (4.62~6.69 GHz) in the 5.0 GHz. In addition, the gain and radiation pattern characteristics of the quadrant band are measured from the measurement results anechoic chamber.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.37 no.2
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• pp.83-90
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• 2000

A simple low-cost and small size 1.88-198 GHz Band RF power amplifier module is developed for IMT2000 repeater. The power amplifier consists of two stage amplifiers that the first stage amplifier is drive amplifier using discrete type P-HEMT (ATF-34143, 800 micron gate width, Agilent Technologies) and the second is power amplifier with 300Bm 1dB gain compression point using GaAs FET(EFA240D-SOT89, 2400 micron gate width, Excelics Semiconductor). this power amplifier module feature a 29.5dBm 1dB gain compression point, 29.5dB gain, 42dBm 3rd order intercept point(OIP3) and -10dB/-l2dB input/output return loss over the 1880-1980 MHz. This PA module is fully integrated using MIC technology into a small size and design by full nonlinear design technologies. The dimensions of this PA module are 42(L) $\times$ 34(W) mm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.873-881
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• 2002

In this paper, the rectangular reflector antenna with 8-dipole array for PCS band (1,750 MHz ~ l,870 MHz) and IMT-2000 band(1,885 MHz ~ 2,200 MHz) is designed and the radiation characteristics are analyzed using the method of moments and HFSS(High Frequency Structure Simulator). To verify the analysis results, rectangular reflector antenna with 8-dipole array is fabricated and the calculated results are compared with the measured results. The measured results show good agreement with the calculated results. As a result of measurements, bandwidth(VSWR< 1.5) of 450 MHz is achieved at PCS and IMT-2000 band and gain is 16 dBi. The designed antenna can be used as the base station antenna for PCS/IMT-2000.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.235-238
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• 2013

In this paper, ㄷ-type MSA for the QMSA structure is proposed. Transformed ㄷ-type MSA is stacked three dielectrics. ㄷ-type MSA structure was load upper & lower surface of the dielectric radiating patch and the ground turn-up left right capacity between parallel plates and radiating patch. Between the dielectric permittivity of the dielectric insert by 2.55 by varing the frequency was shifted. Designed ㄷ-type MSA sturcture of L1 was varied up to 1mm~22mm and frequency was shifted from 3.65GHz~3.84GHz. Also Designed ㄷ-type MSA was measured 1.95dBi maximum gain and bandwidth of 1.61 to 3.64%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.11
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• pp.1101-1110
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• 2011

This paper presents a printed, wideband folded monopole antenna for laptop and tablet computer applications. The proposed antenna is designed to cover bandwidth(2.3~10.6 GHz) of Bluetooth, WiMAX, and UWB system by using the printed folded monopole antenna having asymmetrical line width coupling with a parasitic inverted- L element. Also, wireless LAN band(5.15~5.85 GHz) which interferes with UWB system is rejected by inserting half-wavelength open stub in the folded monopole antenna. -10 dB bandwidth of the fabricated wideband antenna is 2.27~10.6 GHz (4.7:1) and -10 dB band-rejected bandwidth is measured as 700 MHz(5.15~5.85 GHz, 12.72 %). The gain and efficiency of the antenna except for the rejected band are higher than 3.93 dBi and 91.89 % and are measured as -2 dBi and 14.65 % at 5.5 GHz which is band-rejected frequency. The size of the antenna is suitable to install for small space of tablet and laptop computers as 12.75(1 ${\lambda}$/10)${\times}$12(1 ${\lambda}$/11) $mm^2$(${\lambda}$ is free space wavelength at 2.3 GHz). Therefore, we verified that the designed antenna is appropriate for wideband antenna of tablet and laptop PC applications.

• Korean Journal of Food Science and Technology
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• v.53 no.3
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• pp.260-266
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• 2021

This study aimed to identify the hepatoprotective effects of a fermented Chrysanthemum indicum L. water extract. The extraction yield, antioxidant activities (ABTS and DPPH), and content of luteolin and luteolin-7-glucoside were significantly higher in the fermented C. indicum L. water extract (FCI) than in the C. indicum L. water extract. Treatment with FCI (200 ㎍/mL) significantly reduced the activities of gamma(γ)-glutamyl transferase, aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase in HepG2 cells treated with 3% ethanol. Furthermore, FCI did not affect the viability of the HepG2 cells. These results suggest that FCI can be useful for the development of an effective hepatoprotective agent.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05c
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• pp.341-346
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• 1996

사용후핵연료에 대한 장기건식저장과 관련하여 원자로에서 조사된 사용후 핵연료피복관에 대한 산화시험을 공기분위기에서 수행하였다. 피복관 시료의 50$0^{\circ}C$ 공기중 산화시험 결과 산화 초기에 급격한 산화율을 보였으며, 이 후 천이점까지 느리게 산화가 진행되다가 천이 후에는 선형적으로 급격히 무게가 증가하는 지르코늄 합금의 수증기 및 공기중에서의 전형적인 산화양상을 나타내었다. 시편별로는 가장 두꺼운 노내 산화막을 가진 시편이 가장 높은 산화율을 나타내었으며, 노내 산화시 천이점에 근접한 시편들이 가장 낮은 산화율을 보였다. 산화율이 가장 높은 시편의 천이후 영역에서의 산화율은 $\Delta$W ＝ 0.74 t ＋ 38.61과 같은 관계식으로 표현될 수 있었다. 이 때 $\Delta$W는 무게이득(mg/dm$^2$)이고 t는 산화시간(h)을 나타낸다. 시험에 사용된 피복관의 단위 산화막두께(l$\mu$m)에 대한 산화무게증가량은 약 13.4mg/dm$^2$으로 나타났다. 이러한 결과들은 사용후핵연료 중간저장 시설 및 저장캐스크의 설계 전산코드 작성 및 저장시설의 운영에 관련되어 기반자료로 활용될 수 있을 것이다.

• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.755-758
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• 2003

본 논문에서 단거리전용통신(DSRC)용 OBE에 사용되는 5.8GHz 송신측 ASK와 PA를 one-chip화하여 MMIC로 설계를 및 제작하였다. 설계된 ASK-PA는 3V 단일 공급전원을 사용하였고, 능동 소자로서 GaAs MESFET을 사용하였다. ASK는 회로의 복잡도를 줄이기 위해 직접변조 방식을 채택하였고, 인접채널 간섭의 영향을 줄이기 위하여 드레인 제어 변조회로를 사용하였다. 또한 전력증폭기는 2단으로 하여 AB급으로 동작하도록 전압분배 바이어스회로로 구성하였다. 측정결과 3V의 공급전압에서 전체이득 20.63dB, 송신출력 7.8dBm으로 나타냈다. 공정은 ETRI 0.5㎛ GaAs MESFET 공정을 사용하였고, Chip size는 1.2mm×l.4mm이다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.1
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• pp.15-22
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• 2018

In this paper, a microstrip-fed triple-band monopole antenna for WLAN/WiMAX applications was proposed. The proposed antenna is consist of two arc-shaped and one strip line structure, then get the three current path and then designed in order to get triple resonant characteristics. We carried out simulation about parameters. Taking account of coupling effect, Adjusted the length of the two arc-shaped and one strip line, we get the optimized parameters. The proposed antenna is fabricated on an FR-4 substrate, the dielectric constant is 4.4, and total size is $23.5mm(W1){\times}32.0mm(L1){\times}1.0mm(t)$, and its proposed antenna size is $21.0mm(W6){\times}31.0mm(L7)$. From the measured results, return loss of the proposed antenna satisfied return loss 927 MHz (1.844~2.771 GHz), 926 MHz (3.33~4.256 GHz), and 1,415 MHz (5.13~6.545 GHz). And measured results of gain and radiation patterns displayed for operating bands.