• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1236-1242
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• 2014

In this work, a D-band VCO(Voltage Controlled Oscillator) has been developed in a 65-nm CMOS technology. The circuit was designed based on push-push mechanism. The output oscillation frequency of the fabricated VCO varied from 152.7 GHz to 165.8 GHz, and the measured output power was from -17.3 dBm to -8.7 dBm. A phase noise of -90.9 dBc/Hz is achieved at 10 MHz offset. The chip size of the circuit is $470{\mu}m{\times}360{\mu}m$ including the probing pads.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.6
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• pp.893-899
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• 2000

A 900 MHz low-noise amplifier(LNA) with a measured noise figure of 4.8 dB and an associated gain of 13.2 dB was fabricated in a 0.65 $\mu$m CMOS. The inductive source architecture of offers the possibility of achieving the best noise performance. At 900 MHz, the fabricated LNA dissipates 39 mW from a single 3 V power supply including the bias circuitry and provides -26dB input return loss, -17 dB output return loss, and an input 1-dB compression level of -12 dBm.

• Archives of Pharmacal Research
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• v.15 no.2
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• pp.176-183
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• 1992

The stabilizing effects of $\alpha$-$\beta$-$\gamma$- and dimethyl-$\beta$-cyclodextrins $(\alpha$-, $\beta$-, $\gamma$- and DM-$\beta-$-CyDs) on the degradation of hydrocortisone 17-butyrate (HC-17B) in aqueous solution was investigated. Hc-17B underwent a facile hydroxide ion-catalyzed rearrangement to the less active 21-butyrate ester by the apparent first-order kinetics, and maximum stability of HC-17B was obtained at around pH 4.0. The stability of HC-17B was increased by inclusion complexation with $\alpha$-, $\gamma$- and DM-$\beta$-CyD in the pH range of 2.0-8.0 examined, whereas $\beta$-CyD accelerated the degradation of HC-17B at the pH higher than 5.0. The effects of ionic strength, solvent, temperature and CyD concentration were also investigated. Stability constants and apparent degradation rate constants of HC-17B-$\gamma$-CyD and HC-17B-DM-$\beta$-CyD complexes were determined kinetically on the basis of 1:1 complexation. The results suggested that the inclusion complexation with $\gamma$-CyD or DM-$\beta$-CyD was most useful means to enhance the stability of the steroid.

• Journal of the Korean Society for Heat Treatment
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• v.8 no.4
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• pp.333-339
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• 1995

The reduction and diffusion process(R-D process) is an economical way to produce the functional materials which contain rare-earth elements and has been applied to the production of rare-earth magnet meterials($SmCo_5$, $Nd_{15}Fe_{77}B_8$), magneto-optical(MO) target materials and hydrogen storage alloy, etc. However, because of difficult to control of the final composition, the R-D process has not been applied to production of the 2-17 type rare earth permanent magnet materials which contain several elements. Therefore, this work was as a basic study for the production of the 2-17 type rare earth permanent materials with composition $Sm(Co_{0.72}Fe_{0.21}Cu_{0.05}Zr_{0.03})_{7.9}$ by the R-D process, the following were mainy examined ; the amount of metallic calcium as a reductant, homogenization condition of the alloy after the R-D reaction, masuring of magnetic properties of the sample after step aging. The sample prepared by the R-D process contained a little more oxygen than that prepared by the melting method, however, showed almost the same magnetic properties.

• Journal of IKEEE
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• v.17 no.3
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• pp.385-392
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• 2013

In this paper, microstrip antenna to enhance the isolation between transmitting port and receiving port under the proximity objects is proposed, and applied to the Doppler radar sensor working at 5.8GHz ISM band which detects vital signals of a human body. Two 3dB quadrature hybrids are placed around radiation patch to form a balanced structure between transmitting port and receiving port, such that it consistently provides enhanced Tx/Rx isolation and excellent return loss over nearby objects. It is theoretically analyzed and simulated to verify the validity of the proposed application. The fabricated antenna that is 2mm away from the human body, has more than 16 dB return loss and at least 30dB isolation over ISM frequency band of 5.8GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.764-768
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• 2002

In this paper, a double balanced gilbert cell MMIC mixer was realized in Tachyonics SiGe HBT technology. The fabricated mixer has 17 dB conversion gain, 9.8 dB noise figure, -4.2 dBm output 1 dB compression point, -27 dBc RF to IF isolation, and the good input, output matching characteristics. It draws 10 mA from a 3 V supply. The simulation and the measured results are closer to each other, which confirms accuracy of the model library and reliability of the process.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.6
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• pp.598-601
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• 2004

A microstrip filter has been designed and fabricated in hairpin form on a GaAs substrate and its characteristics such as the insertion loss, return loss, and bandwidth have been investigated. The presented filter is realized with relatively small size, 4.5 by 3.6 mm. The insertion loss and return loss of the filter are 1.17 dB and 30 dB, respectively. The filter exhibits 3 dB-bandwidth of 350 MHz at the center frequency, 5.890 GHz. The experimental results show good agreement with the numerical ones. However, the measured center frequency is about 100 MHz higher than the designed one.

• Journal of IKEEE
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• v.8 no.1 s.14
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• pp.79-85
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• 2004

In this paper, Sub harmonic mixer using anti-parallel diode pair is designed for 5.8 GHz Wireless LAN. Conventional mixers mix LO with RF and obtain IF signal from the difference between LO and RF. As frequency increase, LO signal is required increasing LO power, better phase noise, stable LO. But, using APDP, the SHP mixer mix the harmonics of LO signal. Therefore, Sub harmonic mixer is advantage that necessary LO signal frequency was used to operate the 1/2. When LO power is 3 dBm, the conversion loss of manufactured SHP mixer is 12.83 dB. The isolation of LO/IF, 2LO/IF, RF/IF and LO/RF is 39.17 dB, 58 dB, 34 dB, 67.9 dB. And IIP3 is 8 dBm.

• The Journal of Korean Institute of Information Technology
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• v.17 no.3
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• pp.31-41
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• 2019

In this paper, we design and implement the simulator for the transmitter and receiver of 4D-8PSK TCM with 2.0, 2.25, 2.5, and 2.75 bits/symbol-channel transmission efficiency recommended by the CCSDS for satellite communications, and then analyze the BER performance of 4D-8PSK TCM system in AWGN channel. The transmitter of 4D-8PSK TCM is designed in accordance with the recommendation in the CCSDS standard. Meanwhile, for the receiver design of 4D-8PSK TCM, we design the differential decoder generalizing the differential encoder/decoder scheme. The trellis decoding algorithm is designed by applying the auxiliary trellis information and the Viterbi algorithm, and an 8-dimensional constellation mapper equation given in the CCSDS standard is deconstructed to design constellation mapper. Especially, we present the optimized receiver for 4D-8PSK TCM system by investigating the BER performances for the traceback lengths in the Viterbi decoder through computer simulations..

• Annals of Pediatric Endocrinology and Metabolism
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• v.23 no.4
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• pp.210-214
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• 2018

Purpose: Premature adrenarche (PA) often leads to polycystic ovary syndrome (PCOS). Higher anti-mullerian hormone (AMH) levels are reported in PCOS. We studied the androgen profile and AMH profiles in Hispanic girls with PA (aged 5-8 years) and age and body mass index (BMI) matched controls. Methods: Retrospective review of electronic medical records of girls who met the inclusion criteria for premature adrenarche were done. Results: PA girls (n=76) were matched to control girls (n=12) for age (mean${\pm}$standard deviation) ($6.7{\pm}1years$ vs. $6.2{\pm}1.3years$) and BMI ($20{\pm}10kg/m^2$ vs. $17.8{\pm}2.7kg/m^2$). Dehydroepiandrostenedione sulfate ($63.3{\pm}51.3{\mu}g/dL$ vs. $29.8{\pm}17.3{\mu}g/dL$, P<0.001) and testosterone levels ($11.4{\pm}4.8ng/dL$ vs. $8.2{\pm}2.9ng/dL$, P=0.001) were significantly higher in the PA group than controls. AMH values (<14 years: reference range, 0.49-3.15 ng/mL) were $3.2{\pm}2.2ng/mL$ vs. $4.6{\pm}3.2ng/mL$ respectively in the PA and control groups and were not different (P=0.4). AMH did not show a correlation with bone age (P=0.1), and testosterone (P=0.9) in the PA group. 17-hydroxyprogesterone levels (17-OHP ng/dL) were $39.5{\pm}30.5ng/dL$ vs. $36.8{\pm}19.8ng/dL$ in PA versus control girls. The concentration of 17-OHP was not statistically different between the control and PA groups. Conclusion: Higher AMH was not observed in PA girls and no correlation with BA and androgen levels was observed.